WO2017099828A1

WO2017099828A1 - Devices and methods of mobility enhancement and wearable device path selection

Info

Publication number: WO2017099828A1
Application number: PCT/US2016/023802
Authority: WO
Inventors: Kyeongin Jeong; Youn Hyoung Heo; Sangeetha L. Bangolae; Richard C. Burbidge; Alexey Khoryaev
Original assignee: Intel IP Corporation
Priority date: 2015-12-07
Filing date: 2016-03-23
Publication date: 2017-06-15
Also published as: TWI821153B; TW201725926A

Abstract

Devices and methods of reducing UE power consumption are generally described. The UE selects a D2D path or cellular path to use for data communication to an eNB based on at least one of presence of a master UE, a pathloss and transmission power of the D2D and/or cellular path. The UE receives mobility information from the master UE, either an indication that cell selection or handover is to be undertaken or information of the target cell for the UE, in which case the UE does not initiate cell selection or handover. Afterwards, the UE communicates with a target eNB based on the received mobility information.

Description

DEVICES AND METHODS OF MOBILITY ENHANCEMENT AND WEARABLE DEVICE PATH SELECTION

PRIORITY CLAIM

[00011 This application claims the benefit of priority to United States

Provisional Patent Application Serial No. 627264,231 , filed December 7, 2015, and entitled "MOBILITY ENHANCEMENT AND THE PATH SELECTION FOR THE WEARABLE DEVICE," which is incorporated herein by reference in their entirety.

TECHNICAL FIELD

[0002] Embodiments pertain to device-to-device communication in cellular networks. Some embodiments relate to power conservation for wearable devices in cellular and wireless local area network (WLAN) networks, including Third Generation Partnership Project Long Term Evolution (3GPP LTE) networks and LTE advanced (LTE -A) networks as well as 4^th generation (4G) networks and 5^th generation (5G) networks.

BACKGROUND

[0003] With the ever-increasing demand for bandwidth, network resources in cellular networks, such as Long Term Evolution (LTE) networks, are under increasing strain. To increase capacity, the latest version of 3^rd Generation Partnership Project (3GPP) standards introduced direct

communication between proximate user equipment (UE). Device-to-device (D2D) communications occur directly between UEs instead of conveying data between UEs through the radio and core network. D2D devices may include wearable devices, such as fitness trackers, which have grown substantially in popularity over the last several years. Such devices may also communicate using a 3GPP network. Unlike some types of communication devices, the battery provided in a wearable device may be relatively small. It may thus be desirable to find additional ways to reduce power consumption in such devices.

BRIEF DESCRIPTION OF THE FIGURES

[0004] In the figures, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The figures illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.

[0005] FIG. 1 is a functional diagram of a wireless network in accordance with some embodiments.

[0006] FIG. 2 illustrates components of a communication device in accordance with some embodiments.

[0007] FIG. 3 illustrates a block diagram of a communication device in accordance with some embodiments.

[0008] FIG. 4 illustrates another block diagram of a communication device in accordance with some embodiments.

[0009] FIG. 5 illustrates path selection in accordance with some embodiments.

[0010] FIG. 6 illustrates a mobility procedure in accordance with some embodiments.

[0011] FIG. 7 illustrates a method of a UE communicating with an eNB in accordance with some embodiments.

DETAILED DESCRIPTION OF THE INVENTION

[0012] The following description and the drawings sufficiently illustrate specific embodiments to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. Portions and features of some embodiments may be included in, or substituted for, those of other embodiments. Embodiments set forth in the claims encompass all available equivalents of those claims. [0013] FIG. 1 shows an example of a portion of an end-to-end network architecture of a Long Term Evolution (LTE) network with various components of the network in accordance with some embodiments. As used herein, an LTE network refers to both LTE and LTE Advanced (LTE -A) networks as well as other versions of LTE networks to be developed. The network 100 may comprise a radio access network (RAN) (e.g., as depicted, the evolved universal terrestrial radio access network (E-UTRAN) 101 and core network 120 (e.g., shown as an evolved packet core ( FPO) coupled together through an S 1 interface 1 15. For convenience and brevity, only a portion of the core network 120, as well as the RAN 101, is shown in the example.

[0014] The core network 120 may include a mobility management entity

(MME) 122, sening gateway (serving GW) 124, and packet data, network gateway (PDN GW) 126. The MME 122 may be connected through an S6 interface with a ! Home Subscriber Server (HSS) 128 that contains user-related and subscription-related information. The HSS 128 may support mobility management, call and session establishment support, user authentication and access authorization. The RAN 101 may include evolved node Bs (eNBs) 104 (which may operate as base stations) for communicating with user equipment (U E) 102. The eNBs 104 may include macro eNBs 104a and low power (LP) eNBs 104b. The eNBs 104 and UEs 102 may employ the synchronization techniques as described herein. The UEs 102 may include master UEs 102a, such as a smartphone, and wearable devices 102b. The wearable devices 102b may communicate with one of the eNBs 104 (shown in FIG. 1 as the LP eNB 1 4b, but in some embodiments may be the macro eNB 104a) directly through an LTE-Uu interface and/or indirectly through the master UEs 102a via a PCS interface between the wearable device 102b and the master UE 102a.

[0015] The wearable device 102b may employ Proximity -based Services

(ProSe), which may be provided by the 3GPP system based on UEs 102 being in proximity to each other (e.g., sufficiently close to effect D2D discovery and communications). The term D2D and ProSe may be used interchangeably herein. The D2D-capable UEs 1 2 may each store and run a ProSe application that provides the ability to use ProSe sen' ices and communicate over a PCI interface to a ProSe server 144, over a PCS interface to a ProSe Function 142 and over a PC5 interface to other UEs 102 running the ProSe application. The ProSe Function 142 may also be connected to the HSS 128 through a PC4a interface and to a Secured User Plane (SUPL) Location Platform (SLP) 132 (SLP) of a location server through a PC4b interface used to detect the user location or its proximity area.

[0016] The ProSe Function 142 may be able to provision a UE 102 with parameters for ProSe Direct Discovery and ProSe Direct Communication using a Direct Provisioning Function (DPF). In particular, the ProSe Function 142 may be used to provision the UE 102 with Public Land Mobile Network (PLMN)- specific parameters that allow the UE 102 to use ProSe in this specific PLMN. For direct communication used for Public Safety, DPF may also be used to provision the UE 102 with parameters that are used when the UE 102 is not served by the E-UT AN 101. For restricted ProSe Direct Discovery, DPF may also generate and maintain the ProSe Discovery UE ID (PDU ID). The parameters may also include the radio resource management related

configuration. The ProSe Function 142 may also have a direct Direct Discovery Name Management Function 142, used for open ProSe Direct Discovery to allocate and process the mapping of ProSe Applications IDs and ProSe

Application Codes used in ProSe Direct Discovery. The ProSe Function 142 may also use ProSe-related subscriber data stored in the HSS 128 for authorization for each discovery request. The ProSe Function 142 may also provide the UE 102 with security material to protect discovery messages transmitted over the air. In restricted ProSe Direct Discovery, the ProSe

Function 142 may also interact with the Application Server via PC2 reference points for authorization of the discovery requests. The ProSe Function 142 may also have an authorization function 142 for the ProSe UE or user. Between the ProSe Function 142 and the UE 102, information is exchanged using a PC3 interface. [0017] The MME 122 may be similar in function to the control plane of legacy Serving GPRS Support Nodes (SGSN). The MME 122 may manage mobility aspects in access such as gateway selection and tracking area list management. The serving GW 124 may terminate the interface toward the RAN 101 , and route data packets between the RAN 101 and the core network 120. In addition, the serving GW 124 may be a local mobility anchor point for inter-eNB handovers and also may provide an anchor for inter-3GPP mobility. Other responsibilities may include lawful intercept, charging, and some policy enforcement. The serving GW 124 may serve as the local mobility anchor for data bearers when a UE 102 moves between eNBs 104. The serving GW 124 may retain information about the bearers when the UE 1 2 is in idle state (known as ECM_JDLE) and temporarily buffer downlink data while the MME 122 initiates paging of the UE 102 to re-establish the bearers.

[0018] The serving GW 124 and the MME 122 may be implemented in one physical node or separate physical nodes. The MME 122 may be connected with a Home Subscriber Server (HSS) 128 that contains user-related and subscription-related information. The HSS 128 may support mobility management, call and session establishment support, user authentication and access authorization. The protocols running between the UE 102 and the EPC 124 are known as the Non-Access Stratum (NAS) protocol. Other protocols, including RRC, Packet Data Convergence Protocol (PDCP), Radio Layer Control (RLC), Media Access Control (MAC) and Physical Layer (PHY), are terminated in the eNB 104. The NAS layer performs EPS bearer management, authentication for LTE, mobility support for idle mode UEs, paging origination for idle mode UEs, and security handling.

[0019] The RRC layer may provide radio resource management, RRC connection management, and mobility support for connected mode UEs 102. As the RRC control message between the eNB 104 and the UE 102, the RRC layer may handle the broadcast of system information, which is cell-specific, and a dedicated RRC control message, which is UE-specific. In addition, the RRC layer may perform paging, radio bearer control, and control of UE measurement reporting, among others. The PDCP layer may process RRC messages in the control plane and IP packets in the user plane. Depending on the radio bearer, the PDCP layer may perform header compression, security (integrity protection and ciphering), and support for reordering and retransmission during handover. There may be one PDCP entity per radio bearer. The RLC layer may provide segmentation and reassembly of upper layer packets to adapt the packets to a size that can actually be transmitted over the radio interface. For a radio bearer using eri r-free transmission, the RLC layer may also perform, retransmission, to recover from packet losses. Additionally, the RLC layer may perform

reordering to compensate for out-of-order reception due to HARQ (Hybrid Automatic Repeat reQuest) operation in the layer below. There may be one RLC entity per radio bearer. The MAC layer may multiple the data from different radio bearers. By deciding the amount of data that can be transmitted from each radio bearer and instructing the RLC layer as to the size of packets to provide, the MAC layer aims to achieve the negotiated QoS (Quality of Service) for each radio bearer. For the uplink, this process may include reporting to the eNB 104 the amount of buffered data for transmission. The PHY layer may perform CRC insertion, channel coding, physical channel HARQ processing, channel interleaving, scrambl ing, modulation, layer mapping and pre-coding for transport channels. Power control and cell search procedures are also performed as the PFIY functions.

[0020J In general, the functionality of the PDCP, RLC, MAC, and PHY layers, are still applicable for the protocol stack for D2D discovery and D2D communication, although specific features may be added or part of the

mechanisms may be modified for the PCS interface. For instance, radio resource allocation may be performed by eNB scheduling, while radio resource selection, by the UE 102 (either the wearable device 102a or the master UE 102b) within a given resource pool may also be possible for D2D discovery and D2D

communication packet transmission, so a UE autonomous resource selection procedure is added to the MAC and PH layer correspondingly. For D2.D discovery, the Access Stratum (AS) protocol stack may consist of only the MAC and PHY layer, and the MAC layer may receive a discovery- message from, an upper layer (ProSe Protocol), Tire ProSe Protocol may generate the D2D discovery message and interpret the received D2D discovery. The content of D2D discovery message may be transparent to the AS, thus identification of the transmitter or whether the packet is destined for the receiver may not be able to be known to the receiving UE 102 and but may be able to be known in the upper layer. The IP layer may not be used for D2D discovery message. A D2D discover}' message may be communicated in the PSDCH, while D2D communication data may be communicated in the PSSCH.

[0021] The control plane protocol stack for a wearable device 102b may^¬ be similar to that of a typical UE 102a. A wearable -RRC (w-RRC) may handle RRC -related message exchange and the corresponding behaviors between the wearable device 102b and master UE 102a. The master UE 102a may broadcast system information and/or synchronization information according to its serving cell, paging, connection management, measurement control, and mobility functions for one or more registered (or associated) wearable device 102b. in the legacy LTE system, a UE 102 may be either in an idle state or connected state with the eNB 1 4 that controls the serving cell in which the UE 102 is located. In the idle state, in order to support UE mobility (cell

selection/'reselection), the UE 102 may perform cell search, measurements on the neighboring cells and/or the serving cell, and acquisition of system information for the candidate ceil to be reseiected or selected. The details for idle state mobility are specified in 3GPP Technical Specification 36.304. In the connected state, to support UE mobility (handover), the UE 102 may perform cell search, measurements on the neighboring cells and/or the serving cell, measurement report to the eNB according to the measurement configuration by the eNB 102, acquisition of system information and random access procedure for the new cell to be handed over by the eNB. The details for connected state mobility are specified in 3GPP Technical Specification TS36.300 and TS36.331. However the actions described above may consume a significant amount of power, which is not desirable for a Sow power UE (e.g., wearable device 102b) equipped with a small battery,

[0022] The PDN GW 126 may terminate a SGi interface toward the packet data network (PDN). The PDN GW 126 may route data packets between the EPC 120 and the external PDN, and may perform policy enforcement and charging data collection. The PDN GW 126 may be responsible for IP address allocation for the UEs 102, as well as QoS enforcement and flow-based charging according to the rales from, the PCR (Policy and Charging Rules Functions). The PDN GW 126 may also provide an anchor point for mobility devices with non-LTE The external PDN can be anv kind of IP network, as well as an

IP Multimedia Subsystem (IMS) domain. The PDN GW 126 and the serving GW 124 may be implemented in a single physical node or separate physical nodes.

[0023] The eNBs 104 (macro and micro) may terminate the air interface protocol and may be the first point of contact for a UE 102. In some embodiments, an eNB 104 may fulfill various logical functions for the RAN 101 including, but not limited to, RNC (radio network controller functions) such as radio bearer management, uplink and downlink dynamic radio resource management and data packet scheduling, and mobility management. In accordance with embodiments, UEs 102 may be configured to communicate orthogonal frequency division multiplexed (OFDM) communication signals with an eNB 104 over a multicarrier communication channel in accordance with an OFDMA communication technique. The OFDM signals may comprise a plurality of orthogonal subcarriers.

[0024] The SI interface 115 may be the interface that separates the RAN

101 and the EPC 120. It may be split into two parts: the Sl -U, which may carry traffic data between the eNBs 104 and the serving GW⁷ 124, and the S 1-MME, which may be a signaling interface between the eNBs 104 and the MME 122. The X2 interface may be the interface between eNBs 104. The X2 interface may comprise two parts, the X2-C and X2-U. The X2-C may be the control plane interface between the eNBs 104, while the X2-U may be the user plane interface between the eNBs 104,

[0025] With cellular networks, LP cells 104b may be typically used to extend coverage to indoor areas where outdoor signals do not reach well, or to add network capacity in areas with dense usage. In particular, it may be desirable to enhance the coverage of a wireless communication system using cells of different sizes, macrocells, microcells, picocells, and femtocells, to boost system, performance. The cells of different sizes may operate on the same frequency band, or may operate on different frequency bands with each cell operating in a different frequency band or only cells of different sizes operating on different frequency bands. As used herein, the term LP eNB refers to any suitable relatively LP eNB for implementing a smaller cell (smaller than a macro cell) such as a femtocell, a picocell, or a microcell. Femtocell eNBs may be typically provided by a mobile network operator to its residential or enterprise customers. A femtocell may be typically the size of a residential gateway or smaller and generally connect to a broadband line. The femtocell may connect to the mobile operator's mobile network and provide extra coverage in a range of typically 30 to 50 meters. Thus, a LP eNB 104b might be a femtocell eNB since it is coupled through the PDN GW 126. Similarly, a picocell may be a wireless communication system typically covering a small area, such as in-building (offices, shopping mails, train stations, etc.), or more recently in-aircraft. A picocell eNB may generally connect through the X2 link to another eNB such as a macro eNB through its base station controller (BSC) functionality. Thus, LP eNB may be implemented with a picocell eNB since it may be coupled to a macro eNB 104a via an X2 interface. Picocell eNBs or other LP eNBs LP eNB 104b may incorporate some or all functionality of a macro eNB LP eNB 104a . In some cases, this may be referred to as an access point base station or enterprise femtocell.

[0026J Embodiments described herein may be implemented into a system, using any suitably configured hardware and/or software. FIG. 2 illustrates components of a UE in accordance with some embodiments. At least some of the components shown may be used in an eNB or MME, for example, such as the UE 102 or eNB 104 shown in FIG. 1. The UE 200 and other components may be configured to use the synchronization signals as described herein. The UE 200 may be one of the UEs 102 shown in FIG. 1 and may be a stationary, non-mobile device or may be a mobile device. In some

embodiments, the UE 200 may include application circuitr ' 202, baseband circuitry 204, Radio Frequency (RF) circuitry 206, front-end module (FEM) circuitry 208 and one or more antennas 210, coupled together at least as shown . At least some of the baseband circuitry' 204, RF circuitry 206, and FEM circuitry 208 may form a transceiver. In some embodiments, other network elements, such as the eNB may contain some or all of the components shown in FIG. 2. Other of the network elements, such as the MME, may contain an interface, such as the S I interface, to communicate with the eNB over a wired connection regarding the UE.

[0027] The application or processing circuitry 202 may include one or more application processors. For example, the application circuitry 202 may include circuitry such as, but not limited to, one or more single-core or multi- core processors. The processor(s) may include any combination of general- purpose processors and dedicated processors (e.g., graphics processors, application processors, etc.). The processors may be coupled with and/or may include memory/storage and may be configured to execute snstmctions stored in the memory /storage to enable various applications and/or operating sy stems to ran on the system.

[0028] The baseband circuitry 204 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 204 may include one or more baseband processors and/or control logic to process baseband signals received from a receive signal path of the RF circuitry 206 and to generate baseband signals for a transmit signal path of the RF circuitry 206. Baseband processing circuity 204 may interface with the application circuitry 202 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 206. For example, in some embodiments, the baseband circuitry 204 may include a second generation (2G) baseband processor 204a, third generation (3G) baseband processor 204b, fourth generation (4G) baseband processor 204c, and/or other baseband processor(s) 204d for other existing generations, generations in development or to be developed in the future (e.g., fifth generation (5G), 6G, etc.). The baseband circuitr - 204 (e.g., one or more of baseband processors 204a-d) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 206. The radio control functions may include, but are not limited to, signal modulation/demodulation,

encoding/decoding, radio frequency shifting, etc. In some embodiments, modulation/demodulation circuitry of the baseband circuitry 204 may include FFT, preceding, and/or constellation mapping/demapping functionality. In some embodiments, encoding/decoding circuitry of the baseband circuitry 204 may include convolution, tail-biting convolution, turbo, Viterbi, and/or Low Density Parity Check (LDPC) encoder/decoder functionality. Embodiments of modulation/demodulation and encoder/decoder functionality are not limited to these examples and may include other suitable functionality in other embodiments.

[0029] In some embodiments, the baseband circuitry 204 may include elements of a protocol stack such as, for example, elements of an evolved universal terrestrial radio access network (EUTRAN) protocol including, for example, physical (PHY), media access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), and/or radio resource control (RRC) elements. A central processing unit (CPU) 204e of the baseband circuitry 204 may be configured to am elements of the protocol stack for signaling of the PHY, MAC, RLC, PDCP and/or RRC layers. In some embodiments, the baseband circuitry may include one or more audio digital signal processors) (DSP) 204 Γ The audio DSP(s) 204f may be include elements for

compression/decompression and echo cancellation and may include other suitable processing elements in other embodiments. Components of the baseband circuitry may be suitably combined in a single chip, a single chipset, or disposed on a same circuit board in some embodiments. In some embodiments, some or all of the constituent components of the baseband circuitry 204 and the application circuitry 202 may be implemented together such as, for example, on a system on a chip (SOC).

[0030] In some embodiments, the baseband circuitry 204 may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry 204 may support communication with an evolved universal terrestrial radio access network (E- UTRAN) and/or other wireless metropolitan area networks (WMAN), a wireless local area network (WLAN), a wireless personal area network (WPAN).

Embodiments in which the baseband circuitry 204 is configured to support radio communications of more than one wireless protocol may be referred to as multi- mode baseband circuitry. In some embodiments, the device can be configured to operate in accordance with communication standards or other protocols or standards, including Institute of Electrical and Electronic Engineers (IEEE)

802.16 wireless technology (WiMax), IEEE 802.1 1 wireless technology (WiFi) including IEEE 802.11 ad, which operates in the 60 GHz millimeter wave spectrum, various other wireless technologies such as global system for mobile communications (GSM), enhanced data rates for GSM evolution (EDGE), GSM EDGE radio access network (GERAN), universal mobile telecommunications system (UMTS), UMTS terrestrial radio access network (UTRAN), or other 2G, 3G, 4G, 5G, etc. technologies either already developed or to be developed.

[0031] RF circuitry 206 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry 206 may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. RF circuitry 206 may include a receive signal path which may include circuitry to down-convert RF signals received from the FEM circuitry 208 and provide baseband signals to the baseband circuitry 204. RF circuitry 206 may also include a transmit signal path which may include circuitry to up-convert baseband signals provided by the baseband circuitry 204 and provide RF output signals to the FEM circuitiy 208 for transmission,

[0032] In some embodiments, the RF circuitry 206 may include a receive signal path and a transmit signal path. The recei ve signal path of the RF circuitry 206 may include mixer circuitiy 206a, amplifier circuitry 206b and filter circuitry 206c. The transmit signal path of the RF circuitry 206 may include filter circuitry 206c and mixer circuitiy 206a. RF circuitry 206 may also include synthesizer circuitry 206d for synthesizing a frequency for use by the mixer circuitry 206a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitiy 206a of the receive signal path may be configured to down-convert RF signals received from the FEM circuitiy 208 based on the synthesized frequency provided by synthesizer circuitry 206d. The amplifier circuitry 206b may be configured to amplify the down-converted signals and the filter circuitry 206c may be a low -pass filter (LPF) or band-pass filter (EPF) configured to remove unwanted signals from the down-converted signals to generate output baseband signals. Output baseband signals may be provided to the baseband circuitiy 204 for further processing. In some embodiments, the output baseband signals may be zero-frequency baseband signals, although this is not a requirement. In some embodiments, mixer circuitry 206a of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect.

[ΘΘ33| In some embodiments, the mixer circuitry 206a of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 206d to generate RF output signals for the FEM circuitry 208. The baseband signals may be provided by the baseband circuitiy 204 and may be filtered by filter circuitry 206c. The filter circuitry 206c may include a low-pass filter (LPF), although the scope of the embodiments is not limited in this respect.

[0034| In some embodiments, the mixer circuitry 206a of the recei ve signal path and the mixer circuitry 206a of the transmit sign al path may include two or more mixers and may be arranged for quadrature do wncon version and/or upconversion respectively. In some embodiments, the mixer circuitry 206a of the receive signal path and the mixer circuitry 206a of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g..

Hartley image rejection). In some embodiments, the mixer circuitry 206a of the receive signal path and the mixer circuitry 206a may be arranged for direct downconversion and/or direct upconversion, respectively. In some embodiments, the mixer circuitry 206a of the receive signal path and the mixer circuitry 206a of the transmit signal path may be configured for super-heterodyne operation.

[0035] In some embodiments, the output baseband signals and the input baseband signals may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In some alternate embodiments, the output baseband signals and the input baseband signals may be digital baseband signals. In these alternate embodiments, the RF circuitry 206 may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry and the baseband circuitsy 204 may include a digital baseband interface to communicate with the RF circuitry 206.

[0036] In some dual-mode embodiments, a separate radio IC circuitry may be provided for processing signals for each spectrum, although the scope of the embodiments is not limited in this respect,

[0037] In some embodiments, the synthesizer circuitry 206d may be a fractional-N syntliesizer or a fractional N/N+ l syntliesizer, although the scope of the embodiments is not limited in this respect as other types of frequency synthesizers may be suitable. For example, synthesizer circuitry 206d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider.

[0038] The synthesizer circuitry 206d may be configured to synthesize an output frequency for use by the mixer circuitry 206a of the RF circuitry 206 based on a frequency input and a divider control input. In some embodiments, the syntliesizer circuitry 206d may be a fractional N/N+l synthesizer.

[0039] In some embodiments, frequency input may be provided by a voltage controlled oscillator (VCO), although that is not a requirement. Divider control input may be provided by either the baseband circuitry 204 or the applications processor 202 depending on the desired output frequency. In some embodiments, a divider control input (e.g., N) may be determined from a lookup table based on a channel indicated by the applications processor 202.

[0040] Synthesizer circuitry 206d of the RF circuitry 206 may include a divider, a delay-locked loop (DLL), a multiplexer and a phase accumulator. In some embodiments, the divider may be a dual modulus divider (DMD) and the phase accumulator may be a digital phase accumulator (DPA). In some embodiments, the DMD may be configured to divide the input signal by either N or N+ l (e.g., based on a cany out) to provide a fractional division ratio. In some example embodiments, the DLL may include a set of cascaded, tunable, delay elements, a phase detector, a charge pump and a D-type flip-flop. In these embodiments, the delay elements may be configured to break a VCO period up into Nd equal packets of phase, where Nd is the number of delay elements in the delay line. In this way, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle.

[0041] In some embodiments, synthesizer circuitry 206d may be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency may be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency) and used in conjunction with quadrature generator and divider circuitry to generate multiple signals at the carrier frequency with multiple different phases with respect to each other. In some embodiments, the output frequency may be a LO frequency (fLo). In some embodiments, the RF circuitry 206 may include an IQ/polar converter.

[0042] FEM circuitry 208 may include a receive signal path which may include circuitry configured to operate on RF signals received from one or more antennas 210, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry 206 for further processing. FEM circuitry 208 may also include a transmit signal path which may include circuitry configured to amplify signals for transmission provided by the RF circuitry 206 for transmission by one or more of the one or more antennas 210.

[0043] In some embodiments, the FEM circuitry 208 may include a

TX/RX switch to switch between transmit mode and receive mode operation. The FEM circuitry may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitiy may include a low-noise amplifier (LNA) to amplify received RF signals and provide the amplified received RF signals as an output (e.g., to the RF circuitry 206). The transmit signal path of the FEM circuitiy 208 may include a power amplifier (PA) to amplify input RF signals (e.g., provided by RF circuitry 206), and one or more filters to generate RF^' signals for subsequent transmission (e.g., by one or more of the one or more antennas 210).

Θ044] In some embodiments, the UE 200 may include additional elements such as, for example, memory/storage, display, camera, sensor, and/or input'Output (I/O) interface as described in more detail below. In some embodiments, the UE 200 described herein may be part of a portable wireless communication device, such as a personal digital assistant (PDA), a laptop or portable computer with wireless communication capability, a web tablet, a wireless telephone, a smartphone, a wireless headset, a pager, an instant messaging device, a digital camera, an access point, a television, a medical device (e.g., a heart rate monitor, a blood pressure monitor, etc.), or other device that may receive and/or transmit information wireiessly. In some embodiments, the UE 200 may include one or more user interfaces designed to enable user interaction with the system and/or peripheral component interfaces designed to enable peripheral component interaction with the system. For example, the UE 200 may include one or more of a keyboard, a keypad, a touchpad, a display, a sensor, a non-volatile memory port, a universal serial bus (USB) port, an audio jack, a power supply interface, one or more antennas, a graphics processor, an application processor, a speaker, a microphone, and other I/O components. The display may be an LCD or LED screen including a touch screen. The sensor may include a gyro sensor, an accelerometer, a proximity sensor, an ambient light sensor, and a positioning unit. The positioning unit may communicate with components of a positioning network, e.g., a global positioning system (GPS) satellite.

[0045] The antennas 210 may comprise one or more directional or omnidirectional antennas, including, for example, dipole antennas, monopole antennas, patch antennas, loop antennas, microstrip antennas or other types of antennas suitable for transmission of RF signals. In some multiple-input multiple-output (MIMO) embodiments, the antennas 210 may be effectively separated to take advantage of spatial diversity and the different channel characteristics that may result.

[0046] Although the UE 200 is illustrated as having several separate functional elements, one or more of the functional elements may be combined and may be implemented by combinations of software-configured elements, such as processing elements including digital signal processors (DSPs), and/or other hardware elements. For example, some elements may comprise one or more microprocessors, DSPs, field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), radio-frequency integrated circuits (RFICs) and com binations of various hardware and logic circuitry for performing at least the functions described herein. In some embodiments, the functional elements may refer to one or more processes operating on one or more processing elements.

[0047] Embodiments may be implemented in one or a combination of hardware, firmware and software. Embodiments may also be implemented as instructions stored on a computer-readable storage device, which may be read and executed by at least one processor to perform the operations described herein . A computer-readable storage device may include any non-transitory mechanism for storing information in a form readable by a machine (e.g., a computer). For example, a computer-readable storage device may include readonly memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash-memory devices, and other storage devices and media. Some embodiments may include one or more processors and may be configured with instructions stored on a computer-readable storage device.

[0048] FIG. 3 is a block diagram of a communication device in accordance with some embodiments. The device may be a UE or eNB, for example, such as the UE 102 or eNB 104 shown in FIG. 1 that may be configured to track the UE as described herein . The physical layer circuitry 302 may perform various encoding and decoding functions that may include formation of baseband signals for transmission and decoding of received signals. The communication device 300 may also include medium access control layer (MAC) circuitry 304 for controlling access to the wireless medium. The communication device 300 may also include processing circuitry 306, such as one or more single-core or multi-core processors, and memory 308 arranged to perform the operations described herein. The physical layer circuitry 302, MAC circuitry 304 and processing circuitry 306 may handle various radio control functions that enable communication with one or more radio networks compatible with one or more radio technologies and, for example, may contain an LTE stack. The radio control functions may include signal modulation, encoding, decoding, radio frequency shifting, etc. For example, similar to the device shown in FIG. 2, in some embodiments, communication may be enabled with one or more of a WMAN, a WLAN, and a WP AN. In some embodiments, the communication device 300 can be configured to operate in accordance with 3GPP standards or other protocols or standards, including VViMax, WiFi, WiGig, GSM, EDGE, GERAN, UMTS, ί Ί RAN. or other 3G, 3G, 4G, 5G, etc.

technologies either already developed or to be developed. The communication device 300 may include transceiver circuitry 312 to enable communication with other external devices wirelessly and interfaces 314 to enable wired

communication with other external devices. As another example, the transceiver circuitry 312 may perform various transmission and reception functions such as conversion of signals between a baseband range and a Radio Frequency (RF) range . [0049] The antennas 301 may comprise one or more directional or omnidirectional antennas, including, for example, dipole antennas, monopole antennas, patch antennas, loop antennas, microstrip antennas or other types of antennas suitable for transmission of RF signals. In some M1MO embodiments, the antennas 301 may be effectively separated to take advantage of spatial diversity and the different channel characteristics that may result.

[0050] Although the communication device 300 is illustrated as having several separate functional elements, one or more of the functional elements may be combined and may be implemented by combinations of software-configured elements, such as processing elements including DSPs, and/or other hardware elements. For example, some elements may comprise one or more

microprocessors, DSPs, FPGAs, ASICs, RFICs and combinations of various hardware and logic circuitry for performing at least the functions described herein. In some embodiments, the functional elements may refer to one or more processes operating on one or more processing elements. Embodiments may be implemented in one or a combination of hardware, firmware and software. Embodiments may also be implemented as instructions stored on a computer- readable storage device, which may be read and executed by at least one processor to perform the operations described herein.

[0051] FIG. 4 illustrates another block diagram of a communication device in accordance with some embodiments. In alternative embodiments, the communication device 400 may operate as a standalone device or may be connected (e.g., networked) to other communication devices. In a networked deployment, the communication device 400 may operate in the capacity of a server communication device, a client communication device, or both in server- client network environments. In an example, the communication device 400 may act as a peer communication device in peer-to-peer (P2P) (or other distributed) network environment. The communication device 400 may be a UE, eNB, PC, a tablet PC, a STB, a PDA, a mobile telephone, a smart phone, a web appliance, a network router, switch or bridge, or any communication device capable of executing instructions (sequential or otherwise) that specify actions to be taken by that communication device. Further, while only a single communication device is illustrated, the term "communication device" shall also be taken to include any collection of communication devices that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein, such as cloud computing, software as a sen/ice (SaaS), other computer cluster configurations.

0052| Examples, as described herein, may include, or may operate on, logic or a number of components, modules, or mechanisms. Modules are tangible entities (e.g., hardware) capable of performing specified operations and may be configured or arranged in a certain manner. In an example, circuits may be arranged (e.g., internally or with respect to external entities such as other circuits) in a specified manner as a module. In an example, the whole or part of one or more computer systems (e.g., a standalone, client or server computer system) or one or more hardware processors may be configured by firmware or software (e.g., instructions, an application portion, or an application) as a module that operates to perform specified operations. In an example, the software may reside on a communication device readable medium. In an example, the software, when executed by the underlying hardware of the module, causes the hardware to perform the specified operations.

Θ053] Accordingly, the term "module" is understood to encompass a tangible entity, be that an entity that is physically constructed, specifically configured (e.g., hardwired), or temporarily (e.g., transitorily) configured (e.g., programmed) to operate in a specified manner or to perform part or all of any operation described herein . Considering examples in which modules are temporarily configured, each of the modules need not be instantiated at any one moment in time. For example, where the modules comprise a general-purpose hardware processor configured using software, the general-purpose hardware processor may be configured as respective different modules at different times. Software may accordingly configure a hardware processor, for example, to constitute a particular module at one instance of time and to constitute a different module at a different instance of time. [0054] Communication device (e.g., computer system.) 400 may include a hardware processor 402 (e.g., a central processing unit (CPU), a graphics processing unit (GPU), a hardware processor core, or any combination thereof), a main memor - 404 and a static memory 406, some or all of which may communicate with each other via an interlink (e.g., bus) 408. The

communication device 400 may further include a display unit 410, an alphanumeric input device 412 (e.g., a keyboard), and a user interface (UI) navigation device 414 (e.g., a mouse), in an example, the display unit 410, input device 412 and UI navigation device 414 may be a touch screen display. The communication device 400 may additionally include a storage device (e.g., drive unit) 416, a signal generation device 418 (e.g., a speaker), a network interface device 420, and one or more sensors 42, 1 , such as a global positioning system (GPS) sensor, compass, accelerometer, or other sensor. The communication device 400 may include an output controller 428, such as a serial (e.g., universal serial bus (USB), parallel, or other wired or wireless (e.g., infrared (IR), near field communication (NFC), etc.) connection to communicate or control one or more peripheral devices (e.g., a printer, card reader, etc.).

[0055] The storage device 416 may include a communication device readable medium 422, on which is stored one or more sets of data structures or instructions 424 (e.g., software) embodying or utilized by any one or more of the techniques or functions described herein. The instructions 424 may also reside, completely or at least partially, within the main memory 404, within static memory 406, or within the hardware processor 402, during execution thereof by the communication device 400. In an example, one or any combination of the hardware processor 402, the main memory 404, the static memory 406, or the storage device 416 may constitute communication device readable media.

[0056] While the communication device readable medium 422 is illustrated as a single medium, the term "communication device readable medium" may include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) configured to store the one or more instructions 424. [0057] The term "communication device readable medium." may include any medium that is capable of storing, encoding, or carrying instructions for execution by the communication device 400 and that cause the communication device 400 to perform any one or more of the techniques of the present disclosure, or that is capable of storing, encoding or carrying data structures used by or associated with such instructions. Non-limiting communication device readable medium examples may include solid-state memories, and optical and magnetic media. Specifi c examples of communication device readable media may include: non-volatile memory, such as semiconductor memor ' devices (e.g., Electrically Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM)) and flash memory devices: magnetic disks, such as internal hard disks and removable disks;

magneto-optical disks; Random Access Memory- (RAM); and CD-ROM and DVD-ROM disks. In some examples, communication device readable media may include non-transitory communication device readable media. In some examples, communication device readable media may include communication device readable media that is not a transitory propagating signal.

[0058] The instructions 424 may further be transmitted or received over a communications network 426 using a transmission medium via the network interface device 420 utilizing any one of a number of transfer protocols (e.g., frame relay, internet protocol (IP), transmission control protocol (TCP), user datagram protocol (UDP), hypertext transfer protocol (HTTP), etc.). Example communication networks may include a local area network (LAN), a wide area network (WAN), a packet data network (e.g., the Internet), mobile telephone networks (e.g., cellular networks), Plain Old Telephone (POTS) networks, and wireless data networks (e.g., Institute of Electrical and Electronics Engineers (IEEE) 802.1 1 family of standards known as Wi-Fi®, IEEE 802.16 family of standards known as WiMax®), IEEE 802.15.4 family of standards, a Long Term Evolution (LTE) family of standards, a Universal Mobile Telecommunications System. (UMTS) family of standards, peer-to-peer (P2P) networks, among others. In an example, the network interface device 420 may include one or more physical jacks (e.g., Ethernet, coaxial, or phone jacks) or one or more antennas to connect to the communications network 426, in an example, the network interface device 420 may include a plurality of antennas to wirelessly communicate using at least one of single-input multiple-output (SIMO), MIMO, or multiple-input single-output (MISO) techniques. In some examples, the network interface device 420 may wirelessly communicate using Multiple User MIMO techniques. The term "transmission medium" shall he taken to include any intangible medium that is capable of storing, encoding or carrying

instructions for execution by the communication device 400, and includes digital or analog communications signals or other intangible medium to facilitate communication of such software.

[0059] As above, a number of newer types of UEs, including wearable devices and machine type communication (MTC) devices, have limited battery life, leading to a goal of extreme power saving. Unlike MTC devices, which may be stationary, housed in locations that are difficult to get to, and business- related rather than user-related, wearable devices are designed for user interaction. While D2D communications may use any communication technology, e.g., operating on the same frequency band as communications with the eNB (e.g., licensed LTE bands or unlicensed WiFi bands, or Bluetooth bands), the eNB may still be responsible for allocating the D2D communications via RRC messages with the UE.

[0060J To make use of the different communication modes (D2D and

LTE-based), UEs undertake discovery prior to communications. In some embodiments, the UEs may discover each other using a D2D

discovery/communication channel. D2D communications, including discovery, may use any communication technology, e.g., operating on the same frequency band as communications with the eNB. In some embodiments, the UEs may be responsible for conducting D2D communications, while in other embodiments the eNB may still be responsible for allocating the D2D communications via RRC messages with the UEs. Discovery and communications may use the same or different channels or subfrequencies within a particular channel . [0061] D2D communication may be controlled by the UEs or may be eNB-mediated. In the former case, resources of D2D communications may be autonomously selected by the transmitting UE using a random selection within the configured resource pool(s). In the latter case, the UEs may receive from an eNB control information used in D2D communications. The control information may include an indication of resource allocation for transmission by the UE to avoid collision of the resources with other transmissions w ithin the cellular network. The allocation may be allocated specifically for a particular UE or for D2D communications among the UEs and comprise all uplink (UL) spectrum resources. The eNB may also transmit an indication of the resources allocated for separate D2D transmission functions to the UE using, for example, RRC signaling. The transmission functions may include D2D device discovery, data scheduling (scheduling assignment (SAY) and data for D2D communication. ΘΘ62] For low power UEs such as wearable devices in particular, it may be desirable to reduce power by judicious selection of the communication path between the low power UE and the eNB. The low power UE may select a direct LTE path (via LTE-Uu interface) or an indirect D2D path (via a PCS interface through a master UE). Note that although an LTE path is referred to herein, it is to be understood that the path may be a cellular path, in which the network may be LTE-A, 4G, 5G or another network. In some circumstances, the path selection may switch relatively rapidly depending on the environment. FIG. 5 illustrates path selection in accordance with some embodiments. The UEs 502a, 502b and eNB 504 may be shown in one or more of FIGS. 1-4.

[0063] The low power UE 502b (e.g., wearable device) may initially register with a master UE 502a (e.g., a smartphone) if the lo power UE 502b discovers the master UE 502a in its proximity. The discovery can be realized in some embodiments when the low power UE 502b receives a D2D discovery message from the master UE 502a. In some embodiments, after the registration of the low power UE 502b with the master UE 502a, one or both the low power UE 502b and the master UE 502a may provide the registration information between the low power UE 502b and the master UE 502a to the network (e.g. eNB 504 or MME in the core network). The eNB 504 or other network device (such as the MME) may store the registration information for mobility purposes, as discussed in more detail below in relation to FIG. 6. After association or registering with the master UE 502a, the low power UE 502b may select a path for communicating with the eNB 504 using one or more characteristics associated with the low power UE 502b, such as discovery or communication association, the least measured pathloss and/or least calculated transmission power, for example. Other measurements and/or calculations may be used instead of, or in addition to, the above. For example, the amount of

communications of the master UE 502a or number of low power UEs registered with the master UE 502a may impact path selection. The master UE 502a may communicate information to the low power UE 502b for the low power UE 502b to use in path selection determination.

[0064] In some embodiments, after discovery of the master UE 502a as long as the low power UE 502b determines that the master UE 502a is in proximity as indicated by the reception of the discovery or communication associated channel, the low power UE 502b may automatically select the PC5 interface (indirect, D2D path, path 2a and 2b as shown in FIG. 5) for communication with the eNB 504. If the D2D path is unavailable, the low power UE 502b may select the Uu interface (direct LTE path, path 1 ).

Discovery may indicate that the low power U E 502b and the master UE 502a are in communication range of each other. During disco very, the master UE 502a may broadcast an announcement of D2D availability that contains a master UE ID. The announcement may also include an implicit or explicit indication that the announcement is for low power UE registration/ association. The master UE 502a may broadcast the announcement periodically, without regard to whether D2D UEs are in the vicinity, or in response to a request from the low power UE 502b. The periodicity may vary depending on characteristics of the master UE 502a, such as battery power or historical usage; for example, the periodicity may be reduced with increasing battery power or increased use. The announcement can be sent by the ProSe protocol sub-layer or by the w-RRC sub-layer. [0065] Registration or association with the master UE 502a alone, in other embodiments, may not trigger use of the D2D communication for communication with the eNB 504. Instead, after discovery of the master UE 502a, the low power UE 502b may measure or calculate one or both the pathioss and the transmission power of communication signals with the master UE 502a over the PCS interface and/or with the eNB 504 over the Uu interface. The low power UE 502b may use these measurements and calculations to select one of the paths. 3GPP TS 36.213 describes the manner by which the low power UE 502b may calculate the transmission power for the different paths.

[0066] The low power UE 502b may store a threshold value, which was configured by the network (e.g. the eNB or ProSe Funcation or MME or O&M server, etc.), for pathioss and/or the transmission power. The low power UE 502b may determine the relationship between the pathioss and/or the transmission power and the corresponding threshold value to determine which path to select. For example, the low power UE 502b may determine whether the measured pathioss and/or the transmission power of communications from the master UE 502a over the PC5 interface is smaller than a D2D threshold value, and if so the low power UE 502b may select the D2D path with the master UE 502a for communication with the network. Similarly, the low power UE 502b may determine whether the measured pathioss and/or the transmission power of communications from the eNB 504 over the Uu interface is larger than an LTE threshold value, the low power UE 502b may select the D2D path with the master UE 502a for communication with the network. Otherwise the low power UE 502b may select the Uu interface for communication with the network. In other embodiments, if the measured pathioss and/or the transmission power of the Uu interface is smaller than the LTE threshold value (or smaller than that of the PC5 interface), the low power UE 502b may select the Uu interface for communication with the network. Otherwise the low power UE 502b may select the D2D path with the master UE 502a for communication with the network.

[0067] In some embodiments, the decision m ay be combination of the pathioss of both paths - e.g., if either the D2D pathioss is smaller than the D2D threshold value or the LTE pathloss is larger than the LTE threshold value, or if both the D2D pathloss is smaller than the D2D threshold value and the LTE pathloss is larger than the LTE threshold value, the D2D path is selected.

Otherwise the low pow^rer UE 502b may select the Uu interface for

communication with the network. In some embodiments, the decision may be combination of the transmission powers for both paths - e.g., if either the D2D transmission power is smaller than the D2D threshold value or the LTE transmission power is larger than the LTE threshold value, or if both the D 2D transmission power is smaller than the D2D threshold value and the LTE transmission power is larger than the LTE threshold value, the D2D path is selected. Otherwise the lo * power UE 502b may select the Uu interface for communication with the network. In some embodiments, the decision may be combination of the pathloss and the transmission power while in other embodiments the decision may rely on only one of these measurements. In the former case, the decision may be weighted such that one or the other of the measurements takes priority. In some embodiments, the relative difference may result in which path to use - e.g., if the D2D pathloss exceeds the D2D threshold pathloss value by 10% but the D2D transmission power is 20% under the D2D threshold transmission power value, the low power UE 502b may select D2D path. Otherwise the low power UE 502b may select the Uu interface for communication with the network. Ultimately, such calculations may be undertaken to determine the least rate of power drain of the battery of the wearable. The calculations may be stored in a table in the low power UE 502b, for example. In some embodiments, the decision may be based on the comparison of the measured pathloss and/or the transmission power between the D2D path and Uu interface. For example, if the measured pathloss from. D2D path is smaller than the measured pathloss from Uu interface, the low power UE 502b may select the D2D path for communication with the network. Otherwise the low power UE 502b may select the Uu interface for communication with the network . As another example, if the transmission power to D2D path i s smaller than the transmission power to Uu interface, the low power UE 502b may select the D2D path for communication with the network. Otherwise the low power UE 502b may select the Uu interface for communication with the network,

[0068] In some embodiments, the measurement of the pathless and/or the transmission power may occur periodically. The period may be constant or may vary dependent on the environment (e.g., signal strength or pathloss of the D2D and/or LTE path) or type of device. For example, fitness trackers may check pathloss less often than smart watches. The evaluation of the calculated transmission power can be done by the low power UE 502b at every

transmission by the low power UE 502b, periodically even' n transmissions or x ms (where n and x are stored in memory of the low power UE 502b and may be provided by the master UE 502a or eNB 504) or in response to the occurrence of a predetermined event, such as the measured pathloss from the master UE 502a changing by a predetermined offset or becoming worse than a preset threshold.

[0069] In some embodiments, hysteresis or offset may be applied so that the path does not switch rapidly, eating into any power savings. In this case, the hysteresis may be preset, including at least one of a value and/or time or may again be dependent on the environment and/or device type, among others. T ms, for example, the low power UE 502b may select the D2D path for

communication with the network while the D2D pathloss + D2D hysteresis is smaller than the LTE pathloss + LTE offset. Otherwise the low power UE 502b may select the Uu interface for communication with the network. Both hy steresis and offset can be used or one of them only can be used. Instead of D2D hysteresis, D2D offset can be used. Instead of LTE offset, LTE hysteresis can be used. In other embodiments, instead of "+", can be used in front of the hysteresis and/or offset in the above equation. The same may be true for the LTE pathloss, and for the transmission powers. The various offsets may be the same between the D2D path and the LTE path or may be different. The threshold values for offset and hysteresis may be the same in some embodiments and may differ in other embodiments. The eNB 504 and/or the master UE 502a may send the parameters for power control for PCS interface and Uu interface to the low power UE 502b, as well as sending the threshold(s) for one or more of the pathless, transmission power or offset/hysteresis. The eNB 504 and/or the master UE 502a may also send other information to the low power UE 502b, such as the transmission power for the channel to be measured from the eNB 504 and/or the master UE 502a. The announcement from the master UE 502a may also include an implicit or explicit indication that the announcement is for Sow power UE registration/association. As above, the announcement can be sent by the ProSe protocol sub-layer or by the w-RRC sub-layer. The configuration information can be also sent by the ProSe protocol sub-layer or by the w-RRC sub-layer. When the low power UE 502b changes the selected path, the low power UE 502b may inform the master UE 502a and/or the eNB 504 regarding the path change.

[0070] In some embodiments, rather than the low power UE 502b measuring and/or calculating the results, the master UE 502a and/or the eNB 504 may make the switching determination. The master UE 502a and/or the eNB 504 may then transmit an indication of either which path to use or to switch paths from the current path being used to the low power UE 502b. In order for this to occur, in some embodiments, the low power U E 502b may report to the master UE 502a or the eNB 504 regarding its measured results for pathloss from the D2D path and/or Uu interface or its transmission power or the power headroom information to the D2D path and/or Uu interface.

[0071] In addition to path selection, it may be desirable to limit mobility procedures performed by (and communications from) the low power UE. These mobility procedures may include cell selection (which includes reselection procedures) related procedures, such as cell search, measurements on the neighboring cells and/or the serving cell, and acquisition of sy stem information for the candidate cell to camp on, and handover-related procedures, such as cell search, measurements on the neighboring cells and/or the serving cell, measurement reporting to the eNB, random access procedure to the new serving cell, and acquisition of system information from the new serving ceil. In some embodiments, the low? power UE may perform one or more of the cell selection or handover-related procedures above as triggered by the master UE, rather than being signaled by the eNB, In this case, the master UE may determine whether cell selection or handover is required for the low power UE 502b and then provide an initiation indication to the low power UE 502b over the D2D path via a w-RRC control channel or D2D communication channel for the low power UE to initiate the cell selection or handover procedure. The indication may include identification (ID) information of the low power UE, target frequency information, target physical cell ID information and/or target cell global ID information. In addition, the indication may include timing information of the time when cell selection or handover by the low power UE is to occur. The low power UE may transmit to the master UE a response indicating reception of the initiation indication, or may merely perform the cell selection or handover procedures without sending the response. Thus, in such embodiments the low power UE may not, for example, perform measurements on reference signals transmitted by the eNB until indicated by the master UE. Regardless of whetlier or not the low power UE transmits a response, the low power UE, having performed the cell selection or handover procedures based on the indication, may then transmit to the master UE an indication of the completion of the procedure by the low power UE over the D2D path via the w-RRC control channel or D2D communication channel. After completion of cell selection or handover, the low power UE may again no longer perform mobility procedures until the master UE so indicates. Tims, some or all of the mobility procedures may be deactivated until being triggered by a message from the master UE.

[0072] In some embodiments, the low power UE may not itself perform one or more of the cell selection or handover-related procedures. In these embodiments, the master UE may obtain the information for the cell selection or handover and provide this information directly to the low power UE over the D2D path via the RRC control channel or D2D communication channel. As mentioned above, the master UE and/or low power UE may transmit registration information to the eN B, and the network may keep track of the registration for mobility purposes so that the low power UE may avoid performing some or all of the mobility procedures. The information may include ID information of the low power UE, the target frequency information, the target physical cell ID information, the target cell downlink timing information (using the target physical cell synchronization channel information) and the target cell system information. The target cell system information may include, for example, system information block (SIB) 18/19 and SIB 1/2 information and master information block information, such as bandwidth information, Time Division Duplexing (TDD) configuration information, power control-related information, PLMN information, global cell ID information, system frame number (SFN), configurations for D2D discover}' and communication, etc., which is used in order to perform D2D discovery/communication in the target cell. In addition, the indication may include timing information of the time when cell selection or handover by the low power UE is to occur. In some embodiments, the indication transmitted from the low power UE to the master UE may also inform the master UE as to whether the low power UE has successfully received the information. In some embodiments, the indication may also inform the master UE as to whether the low power UE has successfully performed cell (re)selection or handover procedure to the indicated target cell. In some embodiments, the indication may also inform the master UE as to a combination of the above - i.e., whether the low power UE has successfully received the information and/or whether the low power UE has successfully performed cell (re)selection or handover procedure to the indicated target cell.

[0073J In some embodiments, after receiving the cell selection/handover information from the master UE, the low power UE may not itself perform, one or more of the cell selection or handover-related procedures.. The low power UE may use the information in subsequent LTE path communications with the target cell. The low power UE may indicate to the master UE that the information has been received. If timing information indicating when the cell selection/handover occurs is included, the low power UE may wait until after the indicated time for cell selection or handover to have occurred before communicating with the target cell . The master UE may also indicate the downlink and/or uplink timing synchronization information and system information such as SFN periodically to the low power UE over the D2D path via RRC messages or by creating or extending a synchronization channel and system information channel defined for D2D discovery /communication over the PCS interface. For handover, the source eNB may handover both the master UE and the low power UE to a target eNB. This may be done in separate sets of commands through the network, for each device, or in a single set of commands using an alias assigned to the master UE low power U E combination.

[0074] FIG. 6 illustrates a mobility procedure in accordance with some embodiments. The UEs 602a, 602b and eNBs 604a, 604b may be shown in one or more of FIGS. 1-4. As shown in FIG . 6, when the low power UE 602b (shown as a wearable device) powers on, at operation 1 the low power UE 602b may perform initial cell selection according to T^'S 36.304. The low power UE 602b may, for example, scan all RF channels in some or all bands to find a suitable cell. On each carrier frequency, the UE may only search for the strongest cell. Once a suitable cell is found, this cell may be selected. Thus, for example, the low power UE 602b may select the cell which belongs to the eNB 604a as shown.

[0075] After initial cell selection, at operation 2 the lo power UE 602b may acquire the system information for D2D discovery and communication from the cell. The low power UE 602b may receive this information via one or more SIBs. As shown, in some embodiments SIB 18 and/or 19 may carry the configuration information for D2D discovery and communication.

[0076] Once the low power UE 602b acquires the system information, the low power UE 602b may attempt to find a master UE, such as master UE 602a, within communication range . This is not described in FIG. 6, but may be done between operation 2 and operation 3. An ID of a master UE can be pre- configured by the network via, e.g., the ProSe Function or the MME during initial attachment by the low power UE 602b, or by the user, e.g. via the application layer of the low power UE 602b or by the eNB, e.g. via system information or a dedicated RRC message (e.g. RRCConiiectioiiReconfiguration). In the former case, the master UE ID may be registered with the MME or ProSe Function when the master UE 602a attaches to the same cell as the low power UE 602b.

[0077] The low power UE 602b may attempt to find one or more of the available master UEs via a D2D discovery channel (PSDCH) or a D2D communication channel (PSSCH). In some embodiments, the low power UE 602b may attempt to find the available master UEs via a new channel, such as a w-RRC control channel (between the w-RRC layers of the low power UE 602b and the master UE 602a) or a newly introduced physical control channel. The master UE 602a may broadcast an announcement message containing information for use in establishing a D2D connection with the low power UE 602b. The low power UE 602b may receive the announcement message from the master UE 602a, the low power UE 602b may perform

registration/association with the master UE 602a via the D2D communication channel or a new channel. Once the registration/association with the master UE 602a is completed, the low power UE 602b may select the D2D path with the master UE 602a instead of the LTE path with the eNB 604 for communication with the network. The low power UE 602b may subsequently avoid performing the mobility procedures.

[0078] Once the selection of D2D path 602a is performed, at operation 3 the low power UE 602b may avoid performing a cell search, measurements on the neighboring cells and/or the serving cell, and acquiring system information for cell reseiection and/or cell selection. In some embodiments, the low power UE 602b may avoid performing cell search, measurements on the neighboring cells and/or the serving cell, measurement reporting to the eNB, random access procedure to the new serving ceil, and acquisition of system information for handover. In other embodiments, the master UE may inform the network (e.g., the eNB or MME) regarding the paired wearable device information in the mobility aspect. As above, the cell selection/reselection and handover procedures are referred to herein as mobility procedures.

[0079] In some embodiments, the low power UE 602b or the master UE

602a may, after initial cell selection, inform the network (e.g., the eNB 604a or MME) about the registration/association with the master UE 602a, including a paired mobility indication and the master UE ID, The low power UE 602b or the master UE 602a may send the information via an ATTACH/Service Request procedure or Tracking Area Update (TAU) procedure, respectively defined in 3 GPP TS23.401 and TS24.301. The low power UE 602b may subsequently be free from performing the mobility procedures,

0080| At operation 4, the low power UE 602b may communicate with the network over D2D path with the master UE 602a. This may be in accordance with similar communications described above.

[0081] At operation 5, the master UE 602a may move to a new cell due to ceil selection/reselection or handover. For handover, the master UE 602a may receive an RRCConneetionReeonfiguration message to inform, the master UE 602a of a handover command that includes mobilityControlInfo. The handover command may include the information whether the low power UE 602b also needs handover to the same target cell. The low power UE ID information and the timing information indicating when the handover for low power UE 602b occurs may be included in the handover command. Operation 5 may occur either when the master UE 602a receives handover command from the eNB or when the master UE 602a successfully performs handover procedure to the target new serving cell after the reception of handover command. For cell reselection/selection, the master UE 602a may determine the new cell for ceil reselection or ceil selection and camp on the new cell due to cell reselection or cell selection. Operation 5 may thus occur either before the master UE 602a camps on the new serving cell (e.g. when the master UE 602a determines the target serving cell for cell selection or reselection) or after the master UE 602a camps on the new serving cell as the result of cell selection or reselection.

ΘΘ82] At operation 6, cell reselection or handover from the source eNB

604a to the target eNB 604b may occur for the master UE 602a and for the low power UE 602b UE. In some embodiments, the master UE 602a may trigger cell selection/reselection and/or handover for the low power UE 602b, In this case, the master UE 602a may send an indication over the PCS interface via the w- C or D2D communication channel to trigger the low power UE 602b to perform cell reseiection and/or cell selection procedures including cell search, and/or measurements on the neighboring cells and/or the serving cell, and/or acquisition of system information. The indication may include one or more of the low power UE ID, the master UE ID, the target frequency information, the target physical cell ID, the target global cell ID information, the timing information when cell selection/reselection or handover occurs for the low power UE and whether the indication is for cell selection/reselection or handover procedure. Instead of a mere indication, more detailed information may be included in order for the lower power UE 602b to avoid parts of or full operations for a mobility related procedure. For example for cell selection and reseiection, parts of or full steps of cell search, measurements on the neighboring cells and/or the serving cell, acquisition of system information from the new serving cell may be avoided. In order for this avoidance to occur, one or more of the lower power UE ID, the master UE ID, the target frequency information, the target physical cell ID, the target global cell ID, the timing information when cell selection/reselection occurs for the low power UE, whether the information is for celi selection/reselection or handover procedure, downlink timing information according to the new serving cell, MIB, SIB 1, SIB 2, SIB 18, and SIB 19 for the new serving cell may be included at operation 6. For example for handover, parts of or full steps of cell search, measurement on the neighboring cells and/or the serving cell, measurement report to the e^'NB, random access procedures to the new serving cell, and acquisition of system information from the new serving cell may be avoided. In order for this avoidance to occur, one or more of the lower power UE ID information, the master UE ID information, the target frequency information, the target physical cell ID, the target global cell ID, the timing information when handover occurs for the low power UE, and/or whether the information is for cell selection/reselection or handover procedure, downlink timing information according to the new serving celi, uplink timing information to the new serving cell from the m aster UE 602a point of view, MIB, SIB 1, SIB 2, SIB 18, and SIB 19 for the new serving cell may be included at operation 6.

[0083] The master UE 602a may send the indication once cell re selection/selection is completed (for example after the master UE 602a camps on the new? serving cell as a result of cell reseiection/selection) or once handover is completed (for example after the master UE 602a determines that handover or random access to the new serving cell is successful). Alternatively, the UE 602a may send the indication before cell reselectson is completed (for example when the master UE 602a determines cell reseiection/selection to the new serving cell), or once handover command to the new serving cell is received from the cN B 604a.602a

[0084] After the low power UE 602b receives the indication from the master UE 602a, the low power UE 602b may perform the indicated mobility procedures for cell selection reselection or handover to the indicated target cell. After the mobility procedures are completed, the low power UE 602b may subsequently inform the master UE 602a of the completion over the PCS interface, via the w-RRC or D2D communication channel.

[0085] In some embodiments, rather than the low power UE 602b performing mobility procedures, the master UE 602a may transmit more detailed information for the low power UE 602b. In particular, the master UE 602a may transmit information for communication with the target eNB 604b to the low power UE 602b. In particular, when cell reselection/cell selection or hando ver occurs for the master UE 602a, the master UE 602a may transmit all required mobility information directly to the low power UE 602b over the PCS interface via a w-RRC or D2D communication channel, for the new serving cell to be re selected/selected to or to be handed over to. The information may include for example for cell selection/reselection, one or more of the lower power UE ID, the master UE ID, the target frequency information, the target physical cell ID, the target global cell ID, the timing information when cell selection/reselection occurs for the low power UE, whether the information is for cell

selection/reselection or handover procedure, downlink timing information according to the new serving cell (e.g. by forwarding the synchronization channel and/or the downlink reference channel from the new serving cell), MIB (e.g. bandwidth, SFN: System Frame Number, etc.), SIB 1 (e.g. access control information, TDD configuration, PLMN information, power control related information, etc.), SIB 2 (e.g. common configuration for common and dedicated channels, power control related information, etc.), SIB 18 (configuration for D2D communication) and SIB 19 (configuration for D2D discoveiy) for the new serving cell The information may include, for example, for handover, one or more of the lower power UE ID, the master UE ID, the target frequency information, the target physical cell ID, the target global cell ID, the timing information when handover occurs for the low power UE, whether the

information is for cell selection/reselection or handover procedure, downlink timing information according to the new serving cell (e.g. by forwarding the synchronization channel the downlink reference channel from the new serving ceil), uplink timing information to the new? serving cell from the master UE 602a point of view (e.g. master UE's uplink timing advanced information), MIB (e.g. bandwidth, SFN: System Frame Number, etc.), SIB 1 (e.g. access control information, TDD configuration, PLMN information, power control related information, etc.), SIB 2 (e.g. common configuration for common and dedicated channels, power control related information, etc.), SIB 18 (configuration for

D2D communication) and SIB 19 (configuration for D2D discoveiy) for the new serving cell.

[0086] Once the low power UE 602b receives the information from, the master UE 602a, the low power UE 602b can infonn the master UE 602a of the successful reception of the information. In some embodiments, the low pow¾r UE 602b may avoid using the random access procedure for handover to the target eNB 604b. In this case, the target eNB 604b may consider the low power UE 602b to also be successfully handed over when the target eNB 604b receives a random access from the master UE 602a or when the target eNB 604b receives control information (e.g., scheduling request or CSI: Channel Status Information or buffer status report or dedicated R C message such as RRCConnectionReconfigurationComplete, etc) or data from the low power UE 602b.

[0087] The master UE 602a may transmit the information periodically over PCS interface by w-RRC messages or by creating or extending the synchronization channel and system information channel defined for D2D discovery/communication over PC5 interface. The channel may include one or more of the downlink timing information to the serving cell (e.g. by forwarding the synchronization channel), the channel for the measurement or channel estimation from the serving cell (e.g. by forwarding the downlink reference channel from the serving cell) and parts of or full master information from the serving cell (e.g. bandwidth, SFN: System Frame Number, etc.). Separate channels may be designed for different information. In this case, the master UE 602a may update the information to the target eNB 604b when the master UE 602a reselects/selects the target eNB 604b or when the master UE 602a is handed over to the target eNB 604b.

[0088] If the low power UE 602b receives the information described at operation 6, at operation 7 dependent on the details of information signaled from the master UE 602a, the low power UE 602b may perform all of, some of or none of the mobility related procedures corresponding to the cell

selection/reselection or handover. 602a602b

[0089] In some embodiments, if cell reselection/selection is indicated in the signaling the master UE 602a, the low power UE 602b may perform cell search (including timing synchronization) only for the target eNB 604b, measurement only for the target eNB 604b and/or reading system information only from the target eNB 604b. The low power UE 602b may as above determine based on the target frequency information and/or the physical cell ID for the target eNB 604b indicated in the information. Similarly, in some embodiments, if handover is indicated in the signaling from the master UE 602a, the low power UE 602b may perform one or more of ceil search (including timing synchronization) only for the target eNB 604b, measurement only for the target eNB 604b, the random access procedure, and reading system information only from the target eNB 604b. The low power UE 602b may determine the operations to undertake based on the target frequency information and/or the physical cell ID for the target eNB 604b indicated in the information.

[0090] In some embodiments, once the low power UE 602b receives the timing synchronization information and system information of the target eNB 604b directly from the master UE 602a, if cell reselection/selection is indicated in the signaling from the master UE 602a, the low power UE 602b may apply the received timing information and system information for D2D

discovery/communication. If handover is indicated in the signaling from the master UE 602a, the low power UE 602b may apply the received timing information and system information and/or perform a random access procedure to the target eNB 604b. As above, in some embodiments the low power UE 602b may omit the random access procedure to the target eNB 604b during handover if the master UE 602a informs its uplink timing advanced information at operation 6. In this case, the low power UE 602b may use the same uplink timing advanced information to its uplink transmission.

[0091] In some embodiments, once the low power UE 602b receives the timing synchronization information and system information periodically from the master UE 602a, the low? power UE 602b may apply the received timing information and system information if it detects the information has been changed. If the information has not been changed, the low power UE 602b may ignore the new information or apply the previous information.

[0092] The low power UE 602b can inform the master UE 602a of various pieces of information. This may include one or more of: whether the target eNB 604b is or is not successfully detected, whether the measured result on the target eNB 604b is or is not good enough and whether the system information is or is not successfully obtained from the target eNB 604b when cell reselection/selection is indicated in the signaling from the master UE 602a. Similarly, the low power UE 602b can inform the master UE 602a of one or more ofwhether the target eNB 604b is or is not successfully detected, whether the measured result on the target eNB 604b is or is not good enough, whether the system, information is or is not successfully obtained from the target eNB 604b and whether random access to the target eNB 604b is or is not successful completed when handover is indicated in the signaling from the master UE 602a. In order to support the above procedure, the master UE 602a may further include thresholds for the various determinations to enable the low power UE 602b to compare the measured reference signal strength for the target eNB 604b with the threshold and/or to determine whether or not the measured result on the target eNB 604b is good enough. When the low power UE 602b informs the master UE 602a of the status/consequence, the low power UE 602b can also include additional information such as the cause of failure and the measured results for the target eNB 604b and the neighboring cells.

[0093] In some embodiments the control plane protocol stack between the low power UE 602b and the master UE 602a may include a number of connections. The low power UE 602b may handle radio resource control-related message exchange and the corresponding behaviors between the low power UE 602b and the master UE 602a. The master UE 602a may broadcast system information and/or synchronization information to the serving ceil, paging, connection management, measurement control, and mobility functions for one or more registered/associated low power UEs 602b.

[0094] FIG. 7 illustrates a method of a UE communicating with an eNB in accordance with some embodiments. The operations described may be undertaken by any of the low power UEs shown in FIGS. 1-6. At operation 702, the low power UE may establish LTE and D2D communications. This is to say that the low power UE may establish LTE communications with a serving eNB either through initial ceil acquisition or through handover. The low power UE may also establish D2D communications with a master UE. This can be performed either using direct discovery or eNB-mediated discover}' and D2D connection.

[0095] As above, in LTE systems, a UE may be in either idle state or connected state with the eNB that controls the serving cell in which the UE is disposed. In the idle state, to support UE mobility (cell reselection and/or cell selection), the UE may perform cell search, measurements on the neighboring cells and/or the serving cell, and acquisition of system information for the candidate of cell to be reselected or selected. The details of such processes may be specified in the 3GPP specification TS36.304. In the connected state, to support UE mobility (handover), the UE may perform cell search, measurements on the neighboring cells and/or the serving cell, transmit a measurement report according to the measurement configuration by the eNB, acquire system information and perform a random access procedure for the new cell to be handed over by the eNB, The details of such processes may be specified in the 3GPP specification TS36.300 and TS36.331. However the actions described above consume UE power, which is not desirable for low power UEs equipped with a small battery.

Θ096] At operation 704, the low power UE may determine one or more characteristics of the D2D path and the cellular path. The characteristics may include one or more of presence of the D2D path, pathloss and transmission power associated with each path, for example. The low power UE may periodically measure the characteristic.

[0097] At operation 706, the low power UE may select which of the

D2D path and cellular path to use for data communication to the eNB based on the determined character! stic(s). For example, the low power UE may select the D2D path in response to a measurement of at least one of the pathloss of the D2D path being smaller than a D2D threshold value and/or the pathloss of the cellular path being larger than a cellular threshold value. Otherwise the low- power UE may select the Uu interface for the communication with the network. Alternatively, the low power UE may select the D2D path in response to a calculati on of at least one of the transmission power of the D2D path being smaller than a D2D threshold value and/or the transmission power of the cellular path being larger than a cellular threshold value. Otherwise the low power UE may select the Uu interface for the communication with the network. Or, the low power UE may select the D2D path merely due to the presence of the D2D path, in some embodiments, the low power UE may apply hysteresis and/or offset to the measurement of the characteristic to limit a frequency at which selection of whkh of the D2D path and cellular path to use for data communication to the eNB.

[0098] At operation 708, the low power UE may avoid performing mobility related procedures. This is to say that the low power UE not perform mobility related procedures until the low power UE receives specified information over D2D path from the master UE.

[0099] At operation 710, the low power UE may receive cell selection and/or handover information from the master UE. The information may comprise one or more of ID information of the apparatus, ID information of the target cell, downlink uplink timing information of the target ceil, master information system, information of the target eNB, timing information of a time when cell selection or handover is to occur, and whether the mobility procedure is cell selection/reselection or handover, etc. The information may be updated periodically by the master UE. The low power UE may indicate to the master UE that the information has been received or the mobility procedure has been successfully completed or has failed to be completed.

[00100] In response to receiving the information from the master UE at operation 710, the low power UE may at operation 712 communicate with the target eNB based on the information. The low power UE may perform none of, some of or full mobility related procedures dependent on the details of information signaled by the master UE.. The low power UE may initiate the procedure or may merely receive the information to communicate with the eNB from the master UE, the master UE having initiated the procedure for the low power UE.

[00101] Example 1 is an apparatus of a user equipment (UE) compri sing processing circuitry arranged to: select which of a device-to-device (D2D) path to communicate with a master UE and a cellular path to communicate with a source evolved Node-B (eNB) to use for data communication to the eNB based on a characteristic of at least one of the D2D path and cellular path; detect mobility information from the master UE after the selection, the mobility information related to movement from, the source eNB to a target eNB; and initiate a switch in communications from the source eNB to the target eNB based on the received mobility information.

[00102] In Example 2, the subject matter of Example 1 optionally includes, wherein the processing circuitry is further arranged to: initiate a discovery procedure to determine presence of the master UE and establish the D2D path, the characteristic of at least one of the D2D path and cellular path comprising existence of the D2D path such that, when present, the D2D path is automatically selected to use.

[00103] In Example 3, the subject matter of any one or more of Examples

1-2 optionally include wherein: the characteristic of at least one of the D2D path and cellular path comprises at least one of pathloss and transmission power of the at least one of the D2D path and cellular path, and wherein the processing circuitry is further arranged to select the D2D path in response to a measurement of at least one of the pathloss of the D2D path being smaller than a D2D threshold value and the pathloss of the cellular path being larger than a cellular threshold value, and otherwise select the cellular path.

[00104] In Example 4, the subject matter of any one or more of Examples

1-3 optionally include wherein: the characteristic of at least one of the D2D path and cellular path comprises at least one of pathloss and transmission power of the at least one of the D2D path and cellular path, and wherein the processing circuitry is further arranged to select the D2D path in response to a calculation of at least one of the transmission power of the D2D path being smaller than a D2D threshold value and the transmission power of the cellular path being larger than a cellular threshold value, and otherwise select the cellular path.

[00105] In Example 5, the subject matter of any one or more of Examples

1-4 optionally include wherein: the apparatus is a wearable device.

[00106] In Example 6, the subject matter of any one or more of Examples

1-5 optionally include wherein the processing circuitry is further arranged to: peri odically measure the characteristic and select which of the D2D path and cellular path to use for data communication to the eNB, [00107] In Example 7, the subject matter of Example 6 optionally includes, wherein the processing circuitr ' is further arranged to: apply hysteresis to the measurement of the characteristic to limit a frequency at which selection of which of the D2D path and cellular path to use for data communication to the eNB.

[00108] In Example 8, the subject matter of any one or more of Examples

1-7 optionally include wherein the processing circuitry is further arranged to: initiate the switch of communication from the source eNB to the target eNB free from performance by the apparatus of cell selection and handover-related procedures.

[00109] In Example 9, the subject matter of Example 8 optionally includes, wherein the processing circuitry is further arranged to: detect, from the master UE via one of an RRC control channel and D2D communication channel, information regarding one of cell selection and handover; generate a

communication to the target eNB based on the information; and generate an indication that the information has been received for transmission to the master UE via the one of the RRC control channel and D2D communication channel.

[00110] In Example 10, the subject matter of Example 9 optionally includes, wherein: the information comprises identification (ID) information of the apparatus, ID information of the target eNB, downlink timing information of the target eNB, system information of the target eNB and timing information of a time when one of cell selection and handover to the target eNB is to occur, the processing circuitry arranged to initiate communication with the eNB before the time is reached and the target eNB after the time is reached, and the processing circuitry is further arranged to periodically detect, from the master UE via the one of an RRC control channel and D2D communication channel, the downlink timing synchronization information and system information.

[00111] In Example 11, the subject matter of any one or more of

Examples 1-10 optionally include wherein the processing circuity is further arranged to: initiate a cell search, reference signal measurement and system information acquisition based on the mobility information, the mobility information comprising at least one of timing for and an indication of on which eNB to perform cell search, reference signal measurement and system information acquisition.

[00112] In Example 12, the subject matter of any one or more of

Examples 1-1 1 optionally include wherein the processing circuitry is further arranged to: detect, from the master UE via one of an RRC control channel and D2D communication channel, an indication to initiate one of cell selection and handover; initiate the one of the cell selection and handover procedure based on the indication, the one of the cell selection and handover procedure deactivated until being triggered by the indication; and generate an indication to the master UE of completion of the procedure by the wearable device via the one of the RRC control channel and D2D communication channel.

[00113] In Example 13, the subject matter of Example 12 optionally includes, wherein: the indication comprises identification (ID) information of the apparatus, ID in form ation of the target eNB and timing information of a tim e when the one of the cell selection and handover is to occur, the processing circuitry arranged to initiate communication with the eNB before the time is reached and the target eNB after the time is reached.

[00114] In Example 14, the subject matter of any one or more of

Examples 1-13 optionally include wherein the processing circuitry is further arranged to: register with the master UE; and switch communication from the source eNB to the target eNB free from performance by the apparatus of cell search, measurement of cell signals of the source eNB and neighboring eNBs and measurement reporting, handover random access procedure and system information acquisition for cell selection.

[00115] In Example 15, the subject matter of Example 14 optionally includes, wherein the processing circuitry comprises radio frequency circuitry arranged to: communicate with a device in the cellular network via one of an attach, service request, and tracking area update procedure, information comprising registration with the master UE, the information comprising a paired mobility indication and an identification (ID) of the master UE. [00116] In Example 16, the subject matter of any one or more of

Examples 1-15 optionally include further comprising: a plurality of antennas configured to provide communications between the apparatus and the source eNB and between the apparatus and the master UE.

[00117] Example 17 is an apparatus of an evolved NodeB (eNB) comprising processing circuitry arranged to: detect a paired mobility indication and an identification (ID) of the master UE that indicates registration of the lower power UE with the master UE; and initiate communications with the UE through one of a direct cellular path between the apparatus and the UE and an indirect cellular path between the apparatus and the master UE, selection of the communication with the UE dependent on a measurement of at least one of pathless and transmission power of at least one of a D2D path between the master UE and the UE and the direct cellular path.

[00118] In Example 18, the subject matter of Example 17 optionally includes, wherein: the D2D path is selected in response to the measurement being smaller than a D2D threshold value and the pathloss of the direct cellular path being larger than a cellular threshold value, and otherwise the direct cellular path is selected.

[00119] In Example 19, the subject matter of any one or more of

Examples 17-18 optionally include wherein: the D2D path is selected in response to the measurement being smaller than a D2D threshold value and the transmission power of the direct cellular path being larger than a cellular threshold value, and otherwise the direct cellular path is selected.

[00120] In Example 20, the subject matter of any one or more of

Examples 17-19 optionally include wherein: which of the D2D path and direct cellular path to use is selected periodically and hysteresis applied to the measurement to limit a frequency at which selection of which of the D2D path and direct cellular path is used.

[00121] In Example 21, the subject matter of any one or more of

Examples 17-20 optionally include wherein the processing circuitry is further arranged to: initiate handover of communications with the UE to a target eNB free from reception of measurement reports from the UE through the direct cellular path.

[00122] In Example 22, the subject matter of any one or more of

Examples 17-21 optionally include wherein the processing circuitry is further arranged to: initiate handover of communications with the UE to a target eNB based on mobility information of the master UE.

[00123] Example 23 is a computer-readable storage medium that stores instructions for execution by one or more processors of a wearable user equipment (UE) to communicate with an evolved NodeB (eNB) and with a master UE, the one or more processors to configure the wearable UE to: initiate a discovery procedure to determine presence of the master U E, register with the master UE and establish the D2D path; select with which of a device-to-device (D2D) path and a cellular path to communicate with the eNB based on a characteristic of at least one of the D2D path and the cellular path, the D2D path between the low power UE and the master UE; and initiate communications with a target eNB, rather than the eNB, based on mobility information from the master UE, the mobility information comprising identification (ID) information of the apparatus, ID information of the target eN B and timing information of a time when the one of the cell selection and handover is to occur.

[00124] In Example 24, the subject matter of Example 23 optionally includes, wherein the one or more processors further configure the wearable UE to at least one of: select the D2D path to use in response to the D2D path being present, select the D2D path in response to a measurement at least one of pathless of the D2D path being smaller than a D2D threshold value and pathloss of the cellular path being larger than a cellular threshold value, and otherwise select the cellular path, and select the D2D path in response to a measurement at least one of a transmission power of the D2D path being smaller than a D2D threshold value and a transmission power of the cellular path being larger than a cellular threshold value, and otherwise select the cellular path.

[00125] In Example 25, the subject matter of any one or more of

Examples 23-24 optionally include wherein the one or more processors further configure the wearable UE to at least one of: detect from, the master UE at least one of cell selection and handover information, and communicate with the target eNB based on the at least one of cell selection and handover information free from performance by the wearable UE of cell selection and handover-related procedures, the at least one of cell selection and handover information comprising the mobility information, and detect from the master UE an indication to initiate one of cell selection and handover information, and perform the one of the cell selection and handover procedure based on the indication, the indication comprising the mobility information, the one of the cell selection and handover procedure deactivated until being triggered by the indication.

[00126] Example 26 is a UE to communicate with an evolved NodeB (eNB) and with a master UE, the UE comprising: means for initiating a discovery procedure to determine presence of the master UE, register with the master UE and establish the D2D path: means for selecting with which of a device-to-device (D2D) path and a cellular path to communicate with the eNB based on a characteristic of at least one of the D2D path and the cellular path, the D2D path between the low power UE and the master UE; and means for initiating communications with a target eNB, rather than the eNB, based on mobility information from the master UE, the mobility information comprising identification (ID) information of the apparatus, ID information of the target eNB and timing information of a time when the one of the cell selection and handover is to occur.

[00127] In Example 27, the subject matter of Example 26 optionally includes means for selecting the D2D path to use in response to the D2D path being present, means for selecting the D2D path in response to a measurement at least one of pathloss of the D2D path being smaller than a D2D threshold value and pathloss of the cellular path being larger than a cellular threshold value, and otherwise select the cellular path, and means for selecting the D2D path in response to a measurement at least one of a transmission power of the D2D path being smaller than a D2D threshold value and a transmission power of the cellular path being larger than a cellular threshold value, and otherwise select the cellular path.

[00128] In Example 28, the subject matter of any one or more of

Examples 26-27 optionally include means for detecting from the master UE at least one of cell selection and handover information, and communicate with the target eNB based on the at least one of cell selection and handover information free from performance by the wearable UE of cell selection and handover-related procedures, the at least one of cell selection and handover information comprising the mobility information, and means for detecting from the master UE an indication to initiate one of cell selection and handover information, and perform the one of the cell selection and handover procedure based on the indication, the indication comprising the m obility in form ation, the one of the cell selection and handover procedure deactivated until being triggered by the indication.

[00129] Although an embodiment has been described with reference to specific example embodiments, it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the present disclosure. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. The accompanying drawings that form a part hereof show, by way of illustration, and not of limitation, specific embodiments in which the subject matter may be practiced. The embodiments illustrated are described in sufficient detail to enable those skilled in the art to practice the teachings disclosed herein. Other embodiments may be utilized and derived therefrom, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. This Detailed Description, therefore, is not to be taken in a limiting sense, and the scope of various embodiments is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled.

[00130] Such embodiments of the inventive subject matter may be referred to herein, individually and/or collectively, by the term "invention" merely for convenience and without intending to voluntarily limit the scope of this application to any single invention or inventive concept if more than one is in fact disclosed. Thus, although specific embodiments have been illustrated and described herein, it should be appreciated that any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the above description.

[00131] In this document, the terms "a" or "an" are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of "at least one" or "one or more." In this document, the term "or" is used to refer to a nonexclusive or, such that "A or B" includes "A but not B," "B but not A," and "A and B," unless otherwise indicated. In this document, the terms "including" and "in which" are used as the plain-English equivalents of the respective terms "comprising" and "wherein." Also, in the following claims, the terms "including" and "comprising" are open-ended, that is, a system, UE, article, composition, formulation, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.

[00132] The Abstract of the Disclosure is provided to comply with 37 C.F.R. § 1 .72(b), requiring an abstract that will allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim . Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the foliowmg claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.

Claims

CLAIMS What is claimed is:

1. An apparatus of user equipment (UE) comprising processing circuitry arranged to:

select which of a device-to-device (D2D) path to communicate with a master UE and a cellular path to communicate with a source evolved Node-B (eNB) to use for data, communication to the eNB based on a characteristic of at least one of the D2D path and cellular path;

detect mobility information from the master UE after the selection, the mobilit ⁷ information related to movement from the source eNB to a target eNB; and

initiate a switch in communications from the source eNB to the target eNB based on the received mobility information.

2. The apparatus of claim 1, wherein the processing circuitry is further arranged to:

initiate a discovery procedure to determine presence of the m aster UE and establish the D2D path, the characteristic of at least one of the D2D path and cellular path comprising existence of the D2D path such that, when present, the D2D path is automatically selected to use.

3. The apparatus of claim 1 or 2, wherein:

the characteristic of at least one of the D2D path and cellular path comprises at least one of pathloss and transmission power of the at least one of the D2D path and cellular path, and

wherein the processing circuitry is further arranged to select the D2D path in response to a measurement of at least one of the pathloss of the D2D path being smaller than a D2D threshold value and the pathloss of the cellular path being larger than a cellular threshold value, and otherwise select the cellular path.

4. The apparatus of claim 1 or 2, wherein:

wherein the processing circuitry is further arranged to select the D2D path in response to a calculation of at least one of the transmission power of the D2D path being smaller than a D2D threshold value and the transmission power of the cellular path being larger than a cellular threshold value, and otherwise select the cellular path.

5. The apparatus of claim 1 or 2, wherein:

the apparatus is a wearable device.

6. The apparatus of claim 1 or 2, wherein the processing circuitry is further arranged to:

periodically measure the characteristic and select which of the D2D path and cellular path to use for data communication to the eNB.

7. The apparatus of claim 6, wherein the processing circuitry is further arranged to:

apply hysteresis to the measurement of the characteristic to limit a frequency at which selection of which of the D2D path and cellular path to use for data, communication to the eNB,

8. The apparatus of claim 1 or 2, wherein the processing circuitry is further arranged to:

initiate the switch of communication from the source eNB to the target eNB free from performance by the apparatus of cell selection and handover- related procedures.

9. The apparatus of claim 8, wherein the processing circuitry is further arranged to:

detect, from the master UE via one of an RRC control channel and D2D communication channel, information regarding one of cell selection and handover;

generate a communication to the target eNB based on the information; and

generate an indication that the information has been received for transmission to the master UE via the one of the RRC control channel and D2D communication channel.

10. The apparatus of claim 9, wherein :

the information comprises identification (ID) information of the apparatus, ID information of the target eNB, downlink timing information of the target eNB, system information of the target eNB and timing information of a time when one of cell selection and handover to the target eNB is to occur, the processing circuitry arranged to initiate communication with the eNB before the time is reached and the target eNB after the time is reached, and

the processing circuitry is further arranged to periodically detect, from the master UE via the one of an RRC control channel and D2D communication channel, the downlink timing synchronization information and system information.

1 1. The apparatus of claim 1 or 2, wherein the processing circuitry is further arranged to:

initiate a cell search, reference signal measurement and system information acquisition based on the mobility information, the mobility information comprising at least one of timing for and an indication of on which eNB to perform cell search, reference signal measurement and system information acquisition.

12. The apparatus of claim 1 or 2, wherein the processing circuitry is further arranged to:

detect, from the master UE via one of an RRC control channel and D2D communication channel, an indication to initiate one of cell selection and handover;

initiate the one of the cell selection and handover procedure based on the indication, the one of the cell selection and handover procedure deactivated until being triggered by the indication: and

generate an indication to the master UE of completion of the procedure by the wearable device via the one of the RRC control channel and D2D communication channel.

13. The apparatus of claim 12, wherein:

the indication comprises identification (ID) information of the apparatus, ID information of the target eNB and timing information of a time when the one of the cell selection and handover is to occur, the processing circuitry arranged to initiate communication with the eNB before the time is reached and the target eNB after the time is reached.

14. The apparatus of claim I or 2, wherein the processing circuitry is further arranged to:

register with the master UE; and

switch communication from the source eNB to the target eNB free from performance by the apparatus of cell search, measurement of cell signals of the source eNB and neighboring eNBs and measurement reporting, handover random access procedure and system information acquisition for cell selection.

15. The apparatus of claim 14, wherein the processing circuitry comprises radio frequency circuitry arranged to:

communicate with a device in the cellular network via one of an attach, service request, and tracking area update procedure, information comprising registration with the master UE, the information comprising a paired mobility indication and an identification (ID) of the master UE.

16. The apparatus of claim 1 or 2, further comprising:

a plurality of antennas configured to provide communications between the apparatus and the source eNB and between the apparatus and the master UE.

17. An apparatus of an evolved NodeB (eNB) comprising processing circuitr ' arranged to:

detect a paired mobility indication and an identification (ID) of the master UE that indicates registration of the lower power U E with the master UE: and

initiate communications with the UE through one of a direct cellular path between the apparatus and the UE and an indirect cellular path between the apparatus and the master UE, selection of the communication with the UE dependent on a measurement of at least one of pathloss and transmission power of at least one of a D2D path between the master UE and the UE and the direct cellular path.

18. The apparatus of claim 17, wherein:

the D2D path is selected in response to the measurement being smaller than a D2D threshold value and the pathloss of the direct cellular path being larger than a cellular threshold value, and otherwise the direct cellular path is selected.

19. The apparatus of claim 17 or 18, wherein:

the D2D path is selected in response to the measurement being smaller than a D2D threshold value and the transmission power of the direct cellular path being larger than a cellular threshold value, and otherwise the direct cellular path is selected.

20. The apparatus of claim 17 or 18, wherein: which of the D2D path and direct cellular path to use is selected periodically and hysteresis applied to the measurement to limit a frequency at which selection of which of the D2D path and direct cellular path is used.

21. The apparatus of claim 17 or 18, wherein the processing circuitry is further arranged to:

initiate handover of communications with the UE to a target eNB free from reception of measurem ent reports from the UE through the direct cellular path,

22. The apparatus of claim 17 or 18, wherein the processing circuitry is further arranged to:

initiate handover of communications with the UE to a target eNB based on mobility information of the master UE.

23. A computer-readable storage medium that stores instructions for execution by one or more processors of a wearable user equipment (UE) to communicate with an evolved NodeB (eNB) and with a master UE, the one or more processors to configure the wearable UE to:

initiate a discover}' procedure to determine presence of the master UE, register with the master UE and establish the D2D path;

select with which of a device-to-device (D2D) path and a cellular path to communicate with the eNB based on a characteristic of at least one of the D2D path and the cellular path, the D2D path between the low power UE and the master UE; and

initiate communications with a target eNB, rather than the eNB, based on mobility information from the master UE, the mobility information comprising identification (ID) information of the apparatus, ID information of the target eNB and timing information of a time when the one of the cell selection and handover is to occur.

24 , The medium of claim 23, wherein the one or more processors further configure the wearable UE to at least one of:

select the D2D path to use in response to the D2D path being present, select the D2D path in response to a measurement at least one of pathloss of the D2D path being smaller than a D2D threshold value and pathloss of the cellular path being larger than a cellular threshold value, and otherwise select the cellular path, and

select the D2D path in response to a measurement at least one of a transmission power of the D2D path being smaller than a D2D threshold value and a transmission power of the cellular path being larger than a cellular threshold value, and otherwise select the cellular path.

25. The medium of claim 23 or 24, wherein the one or more processors further configure the wearable UE to at least one of:

detect from the master UE at least one of cell selection and handover information, and communicate with the target eNB based on the at least one of cell selection and handover information free from performance by the wearable UE of cell selection and handover-related procedures, the at least one of cell selection and handover information comprising the mobility information, and detect from the master UE an indication to initiate one of cell selection and handover information, and perform the one of the cell selection and handover procedure based on the indication, the indication comprising the mobility information, the one of the cell selection and handover procedure deactivated until being triggered by the indication.