WO2018063998A1 - Systems, methods and devices for a mac-phy split interface - Google Patents

Abstract

A medium access control layer (MAC) and physical layer (PHY) split (MAC-PHY split) is defined in a long term evolution (LTE) and/or LTE New Radio (LTE NR) protocol stack of a radio access network (RAN) node between a central unit (CU) and a distributed unit (DU). For example, a single CU can communicate MAC scheduling information to multiple DUs over a MAC-PHY interface. A structure and interface between the MAC entity in the CU and the PHY entities in DUs is defined through which the required information (from PHY in a DU to MAC in a CU) and scheduling decisions (from MAC in CU to PHY in DU) are transported in both directions for the MAC scheduling operation, taking into account the transport network bandwidth/latency characteristics, and adapting to the fast-changing load distribution across DUs while satisfying the diverse demands.

Description

SYSTEMS, METHODS AND DEVICES FOR A MAC-PHY SPLIT INTERFACE

Related Applications

[0001] This application claims the benefit of United States provisional patent Application No. 62/402,973, filed September 30, 2016, which is incorporated by reference herein in its entirety.

Technical Field

[0002] The present disclosure relates to cellular communications, and more specifically to methods using a MAC-PHY interface between a distributed unit of a New Radio base station and a central unit of a New Radio base station.

Background

[0003] Wireless mobile communication technology uses various standards and protocols to transmit data between a base station and a wireless mobile device. Wireless communication system standards and protocols can include the 3rd

Generation Partnership Project (3GPP) long term evolution (LTE); the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard, which is commonly known to industry groups as worldwide interoperability for microwave access

(WiMAX); and the IEEE 802.1 1 standard for wireless local area networks (WLAN), which is commonly known to industry groups as Wi-Fi. In 3GPP radio access networks (RANs) in LTE systems, the base station can include a RAN Node such as a Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node B (also commonly denoted as evolved Node B, enhanced Node B, eNodeB, or eNB) and/or Radio Network Controller (RNC) in an E-UTRAN, which communicate with a wireless communication device, known as user equipment (UE). In fifth generation (5G) wireless RANs, RAN Nodes can include a 5G Node.

[0004] RANs use a radio access technology (RAT) to communicate between the RAN Node and UE. RANs can include global system for mobile communications (GSM), enhanced data rates for GSM evolution (EDGE) RAN (GERAN), Universal Terrestrial Radio Access Network (UTRAN), and/or E-UTRAN, which provide access to communication services through a core network. Each of the RANs operates according to a specific 3GPP RAT. For example, the GERAN 104 implements GSM and/or EDGE RAT, the UTRAN 106 implements universal mobile telecommunication system (UMTS) RAT or other 3GPP RAT, and the E-UTRAN 108 implements LTE RAT.

[0005] A core network can be connected to the UE through the RAN Node. The core network can include a serving gateway (SGW), a packet data network (PDN) gateway (PGW), an access network detection and selection function (ANDSF) server, an enhanced packet data gateway (ePDG) and/or a mobility management entity (MME).

Brief Description of the Drawings

[0006] FIG. 1 is a diagram illustrating the possible functional splits between a central unit and a distributed unit according to one embodiment.

[0007] FIG. 2 is a diagram illustrating the structure and interface for a MAC-PHY split architecture according to one embodiment.

[0008] FIG. 3 is a schematic diagram illustrating the structure of a long term evolution (LTE) communication frame.

[0009] FIG. 4 is a flow diagram illustrating a method of establishing a MAC-PHY communication link between a central unit (CU) and a distributed unit (DU).

[0010] FIG. 5 is a diagram illustrating an architecture of a system of a network in accordance with some embodiments.

[0011] FIG. 6 is a diagram illustrating example components of a device in accordance with some embodiments.

[0012] FIG. 7 is a diagram illustrating example interfaces of baseband circuitry in accordance with some embodiments.

[0013] FIG. 8 is a block diagram illustrating a control plane protocol stack in accordance with some embodiments.

[0014] FIG. 9 is a block diagram illustrating components, according to some example embodiments, able to read instructions from a machine-readable or computer-readable medium and perform any one or more of the methodologies discussed herein. Detailed Description of Preferred Embodiments

[0015]A detailed description of systems and methods consistent with embodiments of the present disclosure is provided below. While several embodiments are described, it should be understood that the disclosure is not limited to any one embodiment, but instead encompasses numerous alternatives, modifications, and equivalents. In addition, while numerous specific details are set forth in the following description in order to provide a thorough understanding of the embodiments disclosed herein, some embodiments can be practiced without some or all of these details. Moreover, for the purpose of clarity, certain technical material that is known in the related art has not been described in detail in order to avoid unnecessarily obscuring the disclosure.

[0016] Techniques, apparatus and methods are disclosed that enable a medium access control layer (MAC) and physical layer (PHY) split (MAC-PHY split) in a long term evolution (LTE) and/or LTE New Radio (LTE NR) protocol stack of a radio access network (RAN) node between a central unit (CU or sometimes centralized unit) and a distributed unit (DU). For example, a single CU can communicate MAC scheduling information to multiple DUs over a MAC-PHY interface. A structure and interface between the MAC entity in a CU and the PHY entities in DUs is defined through which the required information (from PHY in a DU to MAC in a CU) and scheduling decisions (from MAC in a CU to PHY in a DU) are transported in both directions for the MAC scheduling operation, taking into account the transport network bandwidth/latency characteristics, and adapting to the fast-changing load distribution across DUs while satisfying the diverse demands.

[0017] An interface between the MAC entity in a CU and the PHY entities in DUs can be defined. An alternative interface can be the common public radio interface (CPRI), which has much higher throughput requirements, compared to embodiments disclosed herein.

[0018] A New Radio (NR) base station can spilt protocol stack functionality between a CU and a DU. FIG. 1 illustrates eight possible function split options between CUs and DUs. The protocol stack 100 is represented by an outgoing stack (functions 102-120) and an incoming stack (functions 132-150).

[0019] Options to split functions between a CU and a DU can be done in eight ways. In option 1 , the radio resource control (RRC) layer 102, 132 and data layers 120, 150 are in the CU while packet data convergence protocol (PDCP) layer 104, 134; High-radio link control layer (RLC) 106, 136; Low-RLC 108, 138; High-medium access control layer (MAC) 1 10, 140; Low-MAC 1 12, 142; High-physical layer (PHY) 1 14, 144; Low-PHY 1 16, 146; and radio frequency layers (RF) 1 18, 148 are in the DU. In option 2, the RRC layer 102, 132; data layer 120, 150; and PDCP layer 104, 134 are in the CU while High-RLC 106, 136; Low-RLC 108, 138; High-MAC 1 10, 140; Low-MAC 1 12, 142; High-PHY 1 14, 144; Low-PHY 1 16, 146; and RF 1 18, 148 are in the DU. In option 3, the RRC layer 102, 132; data layer 120, 150; PDCP layer 104, 134; and High-RLC 106, 136 are in the CU while Low-RLC 108, 138; High-MAC 1 10, 140; Low-MAC 1 12, 142; High-PHY 1 14, 144; Low-PHY 1 16, 146; and RF 1 18, 148 are in the DU. In option 4, the RRC layer 102, 132; data layer 120, 150; PDCP layer 104, 134; High-RLC 106, 136; and Low-RLC 108, 138 are in the CU while High-MAC 1 10, 140; Low-MAC 1 12, 142; High-PHY 1 14, 144; Low-PHY 1 16, 146; and RF 1 18, 148 are in the DU. In option 5, the RRC layer 102, 132; data layer 120, 150; PDCP layer 104, 134; High-RLC 106, 136; Low-RLC 108, 138; and High-MAC 1 10, 140 are in the CU while Low-MAC 1 12, 142; High-PHY 1 14, 144; Low-PHY 1 16, 146; and RF 1 18, 148 are in the DU. In option 6, the RRC layer 102, 132; data layer 120, 150; PDCP layer 104, 134; High-RLC 106, 136; Low-RLC 108, 138; High- MAC 1 10, 140; and Low-MAC 1 12, 142 are in the CU while High-PHY 1 14, 144; Low-PHY 1 16, 146; and RF 1 18, 148 are in the DU. In option 7, the RRC layer 102, 132; data layer 120, 150; PDCP layer 104, 134; High-RLC 106, 136; Low-RLC 108, 138; High-MAC 1 10, 140; Low-MAC 1 12, 142; and High-PHY 1 14, 144 are in the CU while Low-PHY 1 16, 146; and RF 1 18, 148 are in the DU. In option 8, the RRC layer 102, 132, data layer 120, 150, PDCP layer 104, 134; High-RLC 106, 136; Low-RLC 108, 138; High-MAC 1 10, 140; Low-MAC 1 12, 142; High-PHY 1 14, 144; and Low- PHY 1 16, 146 are in the CU while RF 1 18, 148 are in the DU.

[0020] In the embodiments described herein, the protocol splitting of option 6 (MAC-PHY split) places the RF components and PHY in the DU and the upper layers (such as the MAC layer) in the CU, with non-ideal transport network interfaces between the CU and DU(s)

[0021] In the MAC-PHY split discussed herein, the MAC entity in the CU may be connected to multiple DUs each comprising at least part of the PHY layer and RF components. One benefit of locating the MAC entity in the CU is centralized scheduling. In LTE, the MAC protocol has been designed as a single lowest entity in the layer-2 architecture to provide multiplexing and de-multiplexing between the transport channels (categorized by how the information is transferred through physical radio interface) and logical channels (categorized by type of information, i.e., diverse control/user-plane traffics). The MAC protocol also provides dynamic physical resource allocations and traffic prioritizations that fulfil the expectations of multiple flows/UEs and quality of service (QoS) requirements over scarce wireless resources. Therefore, a centralized MAC scheduler controlling multiple DUs and having the radio information for multiple cells may allow better interference

management and efficient support of the various features such as CoMP

(Coordinated Multi-Point) for joint processing and coordinated scheduling, CA

(Carrier Aggregation), with a multi-cell view.

[0022] For scheduling, the information required by the MAC scheduler may need to be provided in a timely fashion (e.g., because hybrid automatic repeat request (HARQ) is considered to be part of the MAC). Moreover, scheduling information such as configuration data (e.g., MCS, Layer Mapping, Beamforming, Antenna

Configuration) and resource block allocation may need to be delivered back to the PHY entity in each DU. This means that the MAC scheduler in the CU may require multiple interactions with the PHY entity in the DU in both directions. Such bidirectional interactions between the MAC in the CU and the PHY in each DU may need to be performed in subframe-level timing in order to maximize the efficient use of scarce physical resources.

[0023] In the MAC-PHY split discussed herein, there may be some transport network delay between the CU and DUs (each with different BW/delay

characteristics). Therefore, the interface between the CU and DUs may be designed so that the scheduling operation through bi-directional interactions between the MAC entity in the CU and the PHY entities in DUs can work efficiently, taking into account the transport network characteristics and adapting to the fast-changing load distribution across DUs while satisfying diverse demands. The described structures and interfaces between a MAC entity in a CU and one or more PHY entities in one or more DUs in this disclosure may provide the transport of the required information (from PHY in a DU to MAC in a CU) and scheduling decisions (from MAC in a CU to PHY in a DU) in both directions for the scheduling operation.

[0024] FIG. 2 Illustrates an example structure and interfaces for a MAC-PHY split architecture 200 according to one embodiment. Architecture 200 comprises CU 202 and DUs 204 and 206. The CU 202 comprises a MAC entity 208 and a controller 210. The CU 202 further comprises an interface 212 between the controller 210 and the MAC entity 208, which is an ideal interface (i.e. proprietary). The DU1 204 comprises a PHY entity 214, and the DU2 206 comprises a PHY entity 216.

Interfaces 218 and 220 between the controller 210 in the CU 202 and the PHY entities 214 and 216 in the DUs 204 and 206 can be called MAC-PHY interfaces. In some embodiments, the interface between the controller and the MAC entity within the CU is an ideal interface (i.e., proprietary).

[0025] According to one embodiment, the MAC entity 208 in the CU 202 provides functionalities of the MAC protocol layer. Upper layers (e.g., RLC, PDCP, RRC) are interacting with the MAC entity 208, while the PHY entities 214 and 216 each interact with a radio frequency (RF) component.

[0026] In some embodiments, a DU may be configured to have multiple PHY entities (e.g., one or multiple per PHY configuration). For example, a DU supports multiple physical radio interfaces or multiple verticals (e.g., enhanced mobile broadband (eMBB), ultra-reliable low latency communications (URLLC), and/or massive machine-type communication (mMTC)) within a single physical radio interface. In the case that each vertical is tied to different numerology and

multiplexing between different numerologies is not supported, a CU may be configured to have multiple MAC entities for each numerology.

[0027] Returning to the embodiment of FIG. 2, the controller 210 manages the information delivery between the MAC entity 208 and the PHY entities 214 and 216 in both directions, and governs the control of the MAC-PHY interfaces 218 and 220, as well as PHY configuration for the PHY entities 214 and 216 (including proper routing of the transported information).

[0028] In alternative embodiments, when a DU is configured with multiple PHY entities but has one physical transport network connection to a controller, the controller may perform the multiplexing within the single physical network for the transport of information from/to different PHY entities within that DU (such as wavelength-division multiplexing (WDM) in an optical fiber).

[0029] According to some embodiments, information required for the MAC scheduling may be carried over a MAC-PHY interface. This information may travel from a PHY entity to a controller in a CU. This information may include transport blocks from UEs (including, for example, BSR, PHR as MAC CE). It may also include measurements from PHY (including loT (interference over thermal) level, etc.). It may also include channel estimation from PHY based on sounding reference signal (SRS) and/or UE UL signal AoA (Angle of Arrival), etc. It may further include any other information required for the MAC scheduling.

[0030] Information required for load management across PHY entities and DUs may be carried over a MAC-PHY interface. This information may travel from a PHY entity to a controller in a CU. This information may include cell-level statistics (such as, for example, maximum/minimum/average throughput/latency/outage probability) measured at a PHY entity. This information may also include PHY-level or DU-level (available) processing capability. It may further include any other information required for load management across PHY entities and DUs.

[0031] Information carried over the UL transport channel may also be carried over a MAC-PHY interface. This information may travel from a PHY entity to a controller of a CU. This information may include uplink shared channel (UL-SCH), random access channel (RACH) messages from a PHY entity to the MAC entity. It may further include any other information carried over the UL transport channel.

[0032] Information regarding scheduling decisions by the MAC scheduling may be carried over a MAC-PHY interface. This information may travel from a controller in a CU to a PHY entity. This information may include one or more transport blocks allocated to UEs. This information may also include configuration data (such as modulation and coding scheme (MCS), layer mapping/beamforming information, resource block allocation information, or antenna configuration information). It may further include any other information regarding scheduling decisions by the MAC scheduling.

[0033] Information regarding PHY parameters/configurations from RRC may also be carried over a MAC-PHY interface. This information may travel from a controller in a CU to a PHY entity. This information may include common

parameters/configurations for cell-level adjustments. It may also include dedicated parameters/configurations for each UE served. It may further include any other information regarding PHY parameters/configurations from RRC.

[0034] Information carried over a downlink (DL) transport channel may be carried over a MAC-PHY interface. This information may travel from a controller in a CU to a PHY entity. This information may include broadcast channel (BCH), downlink shared channel (DL-SCH), paging channel (PCH), and/or multicast channel (MCH) messages from a MAC entity to a PHY entity. This information may further include any other information carried over a DL transport channel.

[0035] MAC-PHY interface control/configuration information may be carried over a MAC-PHY interface. This information may travel from a controller in a CU to a PHY entity. Alternatively, this information may travel from a PHY entity to a controller in a CU. This information may include messages for the interface establishment/maintenance. This information may further include transport network characteristic information (e.g., bandwidth (BW), latency). This information may further include multiplexing rule(s) within a single PHY interface for multiple PHY entities within a DU. This information may further include any other MAC-PHY interface control/configuration information.

[0036] A MAC-PHY interface may be established as the communication channel in-between a controller in a CU and a PHY entity in a DU, and may be nested under the physical transport network between a CU and a DU. A controller in a CU may initiate the interface establishment.

[0037] Unique MAC entity and PHY entity identifiers may be determined with the mapping in-between or during the interface establishment. Information delivered through the interface in both directions may be appended with a header of the source and destination identifiers. A controller may perform routing of the information according to the identifiers. In addition to the routing by unique MAC entity/PHY entity identifiers, a controller may provide the mapping of messages between legacy transport channels and legacy physical channels in either and/or both of the DL and UL directions.

[0038] A MAC-PHY interface may support message exchanges such as MAC- PHY SETUP REQUEST, MAC-PHY SETUP RESPONSE and/or MAC-PHY SETUP FAILURE for the interface establishment.

[0039] Information regarding transport network characteristics (e.g., BW, latency, etc.) may be measured and updated periodically and/or per request through the MAC-PHY interface. A controller may notify a (corresponding) MAC entity in a CU of any change of transport network characteristics.

[0040] A MAC-PHY interface may support user-plane or control-plane information delivery in both directions, such as message exchanges conveying control-related information, PHY entity configuration, scheduling-related information/configuration, etc. [0041] FIG. 3 is a schematic diagram 300 illustrating the structure of a long term evolution (LTE) communication frame 305. A frame 305 has a duration of 10 milliseconds (ms). The frame 305 includes 10 subframes 310, each having a duration of 1 ms. Each subframe 310 includes two slots 315, each having a duration of 0.5 ms. Therefore, the frame 305 includes 20 slots 315.

[0042] Each slot 315 includes six or seven Orthogonal Frequency-Division Multiplexing (OFDM) symbols 320. The number of OFDM symbols 320 in each slot 315 is based on the size of the cyclic prefixes (CP) 325. For example, the number of OFDM symbols 320 in the slot 315 is seven while in normal mode CP and six in extended mode CP.

[0043] The smallest allocable unit for transmission is a resource block 330 (i.e., physical resource block (PRB) 330). Transmissions are scheduled by PRB 330. A PRB 330 consists of 12 consecutive subcarriers 335, or 180 kHz, for the duration of one slot 315 (0.5 ms). A resource element 340, which is the smallest defined unit, consists of one OFDM subcarrier during one OFDM symbol interval. In the case of normal mode CP, each PRB 330 consists of 12 x 7 = 84 resource elements 340. Each PRB 330 consists of 72 resource elements 340 in the case of extended mode CP.

[0044] FIG. 4 illustrates a method 400 of establishing a MAC-PHY communication link between a central unit (CU) and a distributed unit (DU). The method can be accomplished by systems such as those shown in FIG. 2 (DU 204 and CU 202) and FIG. 9. In block 402, a controller establishes a MAC-PHY communication channel between the controller of the CU and a physical layer (PHY) entity in the DU. In block 404, the controller determines a unique MAC entity identifier and a unique PHY entity identifier based at least in part on the mapping in-between through the interface establishment. In block 406, the controller appends a header that identifies a source identifier and a destination identifier, the source identifier including the unique PHY entity identifier and the destination identifier including the unique MAC entity identifier. In block 408, the controller routes messages based at least in part on the unique MAC entity identifier or the unique PHY entity identifier. In some embodiments, the controller function is integrated with the MAC entity.

[0045] FIG. 5 illustrates an architecture of a system 500 of a network in

accordance with some embodiments. The system 500 is shown to include a user equipment (UE) 501 and a UE 502. The UEs 501 and 502 are illustrated as smartphones (e.g., handheld touchscreen mobile computing devices connectable to one or more cellular networks), but may also comprise any mobile or non-mobile computing device, such as Personal Data Assistants (PDAs), pagers, laptop computers, desktop computers, wireless handsets, or any computing device including a wireless communications interface.

[0046] In some embodiments, any of the UEs 501 and 502 can comprise an Internet of Things (loT) UE, which can comprise a network access layer designed for low-power loT applications utilizing short-lived UE connections. An loT UE can utilize technologies such as machine-to-machine (M2M) or machine-type

communications (MTC) for exchanging data with an MTC server or device via a public land mobile network (PLMN), Proximity-Based Service (ProSe) or device-to- device (D2D) communication, sensor networks, or loT networks. The M2M or MTC exchange of data may be a machine-initiated exchange of data. An loT network describes interconnecting loT UEs, which may include uniquely identifiable embedded computing devices (within the Internet infrastructure), with short-lived connections. The loT UEs may execute background applications (e.g., keep-alive messages, status updates, etc.) to facilitate the connections of the loT network.

[0047] The UEs 501 and 502 may be configured to connect, e.g.,

communicatively couple, with a radio access network (RAN) 510. The RAN 510 may be, for example, an Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN), a NextGen RAN (NG RAN), or some other type of RAN. The UEs 501 and 502 utilize connections 503 and 504, respectively, each of which comprises a physical communications interface or layer (discussed in further detail below); in this example, the connections 503 and 504 are illustrated as an air interface to enable communicative coupling, and can be consistent with cellular communications protocols, such as a Global System for Mobile Communications (GSM) protocol, a code-division multiple access (CDMA) network protocol, a Push-to-Talk (PTT) protocol, a PTT over Cellular (POC) protocol, a Universal Mobile Telecommunications System (UMTS) protocol, a 3GPP Long Term Evolution (LTE) protocol, a fifth generation (5G) protocol, a New Radio (NR) protocol, and the like.

[0048] In this embodiment, the UEs 501 and 502 may further directly exchange communication data via a ProSe interface 505. The ProSe interface 505 may alternatively be referred to as a sidelink interface comprising one or more logical channels, including but not limited to a Physical Sidelink Control Channel (PSCCH), a Physical Sidelink Shared Channel (PSSCH), a Physical Sidelink Discovery

Channel (PSDCH), and a Physical Sidelink Broadcast Channel (PSBCH).

[0049] The UE 502 is shown to be configured to access an access point (AP) 506 via connection 507. The connection 507 can comprise a local wireless connection, such as a connection consistent with any IEEE 802.1 1 protocol, wherein the AP 506 would comprise a wireless fidelity (WiFi®) router. In this example, the AP 506 is shown to be connected to the Internet without connecting to the core network of the wireless system (described in further detail below).

[0050] The RAN 510 can include one or more access nodes that enable the connections 503 and 504. These access nodes (ANs) can be referred to as base stations (BSs), NodeBs, evolved NodeBs (eNBs), next Generation NodeBs (gNB), RAN nodes, and so forth, and can comprise ground stations (e.g., terrestrial access points) or satellite stations providing coverage within a geographic area (e.g., a cell). The RAN 510 may include one or more RAN nodes for providing macrocells, e.g., macro RAN node 51 1 , and one or more RAN nodes for providing femtocells or picocells (e.g., cells having smaller coverage areas, smaller user capacity, or higher bandwidth compared to macrocells), e.g., low power (LP) RAN node 512.

[0051] Any of the RAN nodes 51 1 and 512 can terminate the air interface protocol and can be the first point of contact for the UEs 501 and 502. In some

embodiments, any of the RAN nodes 51 1 and 512 can fulfill various logical functions for the RAN 510 including, but not limited to, radio network controller (RNC) functions such as radio bearer management, uplink and downlink dynamic radio resource management and data packet scheduling, and mobility management.

[0052] In accordance with some embodiments, the UEs 501 and 502 can be configured to communicate using Orthogonal Frequency-Division Multiplexing

(OFDM) communication signals with each other or with any of the RAN nodes 51 1 and 512 over a multicarrier communication channel in accordance various

communication techniques, such as, but not limited to, an Orthogonal Frequency- Division Multiple Access (OFDMA) communication technique (e.g., for downlink communications) or a Single Carrier Frequency Division Multiple Access (SC-FDMA) communication technique (e.g., for uplink and ProSe or sidelink communications), although the scope of the embodiments is not limited in this respect. The OFDM signals can comprise a plurality of orthogonal subcarriers. [0053] In some embodiments, a downlink resource grid can be used for downlink transmissions from any of the RAN nodes 51 1 and 512 to the UEs 501 and 502, while uplink transmissions can utilize similar techniques. The grid can be a time- frequency grid, called a resource grid or time-frequency resource grid, which is the physical resource in the downlink in each slot. Such a time-frequency plane representation is a common practice for OFDM systems, which makes it intuitive for radio resource allocation. Each column and each row of the resource grid corresponds to one OFDM symbol and one OFDM subcarrier, respectively. The duration of the resource grid in the time domain corresponds to one slot in a radio frame. The smallest time-frequency unit in a resource grid is denoted as a resource element. Each resource grid comprises a number of resource blocks, which describe the mapping of certain physical channels to resource elements. Each resource block comprises a collection of resource elements; in the frequency domain, this may represent the smallest quantity of resources that currently can be allocated. There are several different physical downlink channels that are conveyed using such resource blocks.

[0054] The physical downlink shared channel (PDSCH) may carry user data and higher-layer signaling to the UEs 501 and 502. The physical downlink control channel (PDCCH) may carry information about the transport format and resource allocations related to the PDSCH channel, among other things. It may also inform the UEs 501 and 502 about the transport format, resource allocation, and HARQ (hybrid automatic repeat request) information related to the uplink shared channel. Typically, downlink scheduling (assigning control and shared channel resource blocks to the UE 502 within a cell) may be performed at any of the RAN nodes 51 1 and 512 based on channel quality information fed back from any of the UEs 501 and 502. The downlink resource assignment information may be sent on the PDCCH used for (e.g., assigned to) each of the UEs 501 and 502.

[0055] The PDCCH may use control channel elements (CCEs) to convey the control information. Before being mapped to resource elements, the PDCCH complex-valued symbols may first be organized into quadruplets, which may then be permuted using a sub-block interleaver for rate matching. Each PDCCH may be transmitted using one or more of these CCEs, where each CCE may correspond to nine sets of four physical resource elements known as resource element groups (REGs). Four Quadrature Phase Shift Keying (QPSK) symbols may be mapped to each REG. The PDCCH can be transmitted using one or more CCEs, depending on the size of the downlink control information (DCI) and the channel condition. There can be four or more different PDCCH formats defined in LTE with different numbers of CCEs (e.g., aggregation level, L=1 , 2, 4, or 8).

[0056] Some embodiments may use concepts for resource allocation for control channel information that are an extension of the above-described concepts. For example, some embodiments may utilize an enhanced physical downlink control channel (EPDCCH) that uses PDSCH resources for control information transmission. The EPDCCH may be transmitted using one or more enhanced the control channel elements (ECCEs). Similar to above, each ECCE may correspond to nine sets of four physical resource elements known as enhanced resource element groups (EREGs). An ECCE may have other numbers of EREGs in some situations.

[0057] The RAN 510 is shown to be communicatively coupled to a core network (CN) 520 via an S1 interface 513. In embodiments, the CN 520 may be an evolved packet core (EPC) network, a NextGen Packet Core (NPC) network, or some other type of CN. In this embodiment the S1 interface 513 is split into two parts: the S1 -U interface 514, which carries traffic data between the RAN nodes 51 1 and 512 and a serving gateway (S-GW) 522, and an S1 -mobility management entity (MME) interface 515, which is a signaling interface between the RAN nodes 51 1 and 512 and MMEs 521 .

[0058] In this embodiment, the CN 520 comprises the MMEs 521 , the S-GW 522, a Packet Data Network (PDN) Gateway (P-GW) 523, and a home subscriber server (HSS) 524. The MMEs 521 may be similar in function to the control plane of legacy Serving General Packet Radio Service (GPRS) Support Nodes (SGSN). The MMEs 521 may manage mobility aspects in access such as gateway selection and tracking area list management. The HSS 524 may comprise a database for network users, including subscription-related information to support the network entities' handling of communication sessions. The CN 520 may comprise one or several HSSs 524, depending on the number of mobile subscribers, on the capacity of the equipment, on the organization of the network, etc. For example, the HSS 524 can provide support for routing/roaming, authentication, authorization, naming/addressing resolution, location dependencies, etc.

[0059] The S-GW 522 may terminate the S1 interface 513 towards the RAN 510, and routes data packets between the RAN 510 and the CN 520. In addition, the S- GW 522 may be a local mobility anchor point for inter-RAN node handovers and also may provide an anchor for inter-3GPP mobility. Other responsibilities may include lawful intercept, charging, and some policy enforcement.

[0060] The P-GW 523 may terminate an SGi interface toward a PDN. The P-GW 523 may route data packets between the CN 520 (e.g., an EPC network) and external networks such as a network including an application server 530

(alternatively referred to as application function (AF)) via an Internet Protocol (IP) interface 525. Generally, the application server 530 may be an element offering applications that use IP bearer resources with the core network (e.g., UMTS Packet Services (PS) domain, LTE PS data services, etc.). In this embodiment, the P-GW 523 is shown to be communicatively coupled to an application server 530 via an IP communications interface 525. The application server 530 can also be configured to support one or more communication services (e.g., Voice-over-Internet Protocol (VoIP) sessions, PTT sessions, group communication sessions, social networking services, etc.) for the UEs 501 and 502 via the CN 520.

[0061] The P-GW 523 may further be a node for policy enforcement and charging data collection. A Policy and Charging Rules Function (PCRF) 526 is the policy and charging control element of the CN 520. In a non-roaming scenario, there may be a single PCRF in the Home Public Land Mobile Network (HPLMN) associated with a UE's Internet Protocol Connectivity Access Network (IP-CAN) session. In a roaming scenario with local breakout of traffic, there may be two PCRFs associated with a UE's IP-CAN session: a Home PCRF (H-PCRF) within a HPLMN and a Visited PCRF (V-PCRF) within a Visited Public Land Mobile Network (VPLMN). The PCRF 526 may be communicatively coupled to the application server 530 via the P-GW 523. The application server 530 may signal the PCRF 526 to indicate a new service flow and select the appropriate Quality of Service (QoS) and charging parameters. The PCRF 526 may provision this rule into a Policy and Charging Enforcement Function (PCEF) (not shown) with the appropriate traffic flow template (TFT) and QoS class of identifier (QCI), which commences the QoS and charging as specified by the application server 530.

[0062] FIG. 6 illustrates example components of a device 600 in accordance with some embodiments. In some embodiments, the device 600 may include application circuitry 602, baseband circuitry 604, Radio Frequency (RF) circuitry 606, front-end module (FEM) circuitry 608, one or more antennas 610, and power management circuitry (PMC) 612 coupled together at least as shown. The components of the illustrated device 600 may be included in a UE or a RAN node. In some

embodiments, the device 600 may include fewer elements (e.g., a RAN node may not utilize application circuitry 602, and instead include a processor/controller to process IP data received from an EPC). In some embodiments, the device 600 may include additional elements such as, for example, memory/storage, display, camera, sensor, or input/output (I/O) interface. In other embodiments, the

components described below may be included in more than one device (e.g., said circuitries may be separately included in more than one device for Cloud-RAN (C- RAN) implementations).

[0063] The application circuitry 602 may include one or more application processors. For example, the application circuitry 602 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 or may include memory/storage and may be configured to execute instructions stored in the memory/storage to enable various applications or operating systems to run on the device 600. In some embodiments, processors of application circuitry 602 may process IP data packets received from an EPC.

[0064] The baseband circuitry 604 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 604 may include one or more baseband processors or control logic to process baseband signals received from a receive signal path of the RF circuitry 606 and to generate baseband signals for a transmit signal path of the RF circuitry 606. Baseband processing circuity 604 may interface with the application circuitry 602 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 606. For example, in some embodiments, the baseband circuitry 604 may include a third generation (3G) baseband processor 604A, a fourth generation (4G) baseband processor 604B, a fifth generation (5G) baseband processor 604C, or other baseband processor(s) 604D for other existing generations, generations in development or to be developed in the future (e.g., second generation (2G), sixth generation (6G), etc.). The baseband circuitry 604 (e.g., one or more of baseband processors 604A-D) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 606. In other embodiments, some or all of the functionality of baseband processors 604A-D may be included in modules stored in the memory 604G and executed via a Central Processing Unit (CPU) 604E. 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 604 may include Fast-Fourier Transform (FFT), precoding, or constellation mapping/demapping functionality. In some embodiments,

encoding/decoding circuitry of the baseband circuitry 604 may include convolution, tail-biting convolution, turbo, Viterbi, 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.

[0065] In some embodiments, the baseband circuitry 604 may include one or more audio digital signal processor(s) (DSP) 604F. The audio DSP(s) 604F 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 604 and the application circuitry 602 may be implemented together such as, for example, on a system on a chip (SOC).

[0066] In some embodiments, the baseband circuitry 604 may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry 604 may support communication with an evolved universal terrestrial radio access network (EUTRAN) or other wireless metropolitan area networks (WMAN), a wireless local area network (WLAN), or a wireless personal area network (WPAN). Embodiments in which the baseband circuitry 604 is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry.

[0067] RF circuitry 606 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry 606 may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. The RF circuitry 606 may include a receive signal path which may include circuitry to down-convert RF signals received from the FEM circuitry 608 and provide baseband signals to the baseband circuitry 604. RF circuitry 606 may also include a transmit signal path which may include circuitry to up-convert baseband signals provided by the baseband circuitry 604 and provide RF output signals to the FEM circuitry 608 for transmission.

[0068] In some embodiments, the receive signal path of the RF circuitry 606 may include mixer circuitry 606A, amplifier circuitry 606B and filter circuitry 606C. In some embodiments, the transmit signal path of the RF circuitry 606 may include filter circuitry 606C and mixer circuitry 606A. RF circuitry 606 may also include

synthesizer circuitry 606D for synthesizing a frequency for use by the mixer circuitry 606A of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 606A of the receive signal path may be configured to down- convert RF signals received from the FEM circuitry 608 based on the synthesized frequency provided by synthesizer circuitry 606D. The amplifier circuitry 606B may be configured to amplify the down-converted signals and the filter circuitry 606C may be a low-pass filter (LPF) or band-pass filter (BPF) configured to remove unwanted signals from the down-converted signals to generate output baseband signals.

Output baseband signals may be provided to the baseband circuitry 604 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, the mixer circuitry 606A of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect.

[0069] In some embodiments, the mixer circuitry 606A of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 606D to generate RF output signals for the FEM circuitry 608. The baseband signals may be provided by the baseband circuitry 604 and may be filtered by the filter circuitry 606C.

[0070] In some embodiments, the mixer circuitry 606A of the receive signal path and the mixer circuitry 606A of the transmit signal path may include two or more mixers and may be arranged for quadrature downconversion and upconversion, respectively. In some embodiments, the mixer circuitry 606A of the receive signal path and the mixer circuitry 606A 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 606A of the receive signal path and the mixer circuitry 606A may be arranged for direct downconversion and direct upconversion, respectively. In some embodiments, the mixer circuitry 606A of the receive signal path and the mixer circuitry 606A of the transmit signal path may be configured for super-heterodyne operation.

[0071] 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 606 may include analog-to- digital converter (ADC) and digital-to-analog converter (DAC) circuitry and the baseband circuitry 604 may include a digital baseband interface to communicate with the RF circuitry 606.

[0072] 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.

[0073] In some embodiments, the synthesizer circuitry 606D may be a fractional- N synthesizer or a fractional N/N+1 synthesizer, 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 606D may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider.

[0074] The synthesizer circuitry 606D may be configured to synthesize an output frequency for use by the mixer circuitry 606A of the RF circuitry 606 based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry 606D may be a fractional N/N+1 synthesizer.

[0075] 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 604 or the application circuitry 602 (such as an applications processor) 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 application circuitry 602.

[0076] Synthesizer circuitry 606D of the RF circuitry 606 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+1 (e.g., based on a carry 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.

[0077] In some embodiments, the synthesizer circuitry 606D 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 606 may include an IQ/polar converter.

[0078] FEM circuitry 608 may include a receive signal path which may include circuitry configured to operate on RF signals received from one or more antennas 610, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry 606 for further processing. The FEM circuitry 608 may also include a transmit signal path which may include circuitry configured to amplify signals for transmission provided by the RF circuitry 606 for transmission by one or more of the one or more antennas 610. In various embodiments, the amplification through the transmit or receive signal paths may be done solely in the RF circuitry 606, solely in the FEM circuitry 608, or in both the RF circuitry 606 and the FEM circuitry 608.

[0079] In some embodiments, the FEM circuitry 608 may include a TX/RX switch to switch between transmit mode and receive mode operation. The FEM circuitry 608 may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry 608 may include an LNA to amplify received RF signals and provide the amplified received RF signals as an output (e.g., to the RF circuitry 606). The transmit signal path of the FEM circuitry 608 may include a power amplifier (PA) to amplify input RF signals (e.g., provided by the RF circuitry 606), and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 610).

[0080] In some embodiments, the PMC 612 may manage power provided to the baseband circuitry 604. In particular, the PMC 612 may control power-source selection, voltage scaling, battery charging, or DC-to-DC conversion. The PMC 612 may often be included when the device 600 is capable of being powered by a battery, for example, when the device 600 is included in a UE. The PMC 612 may increase the power conversion efficiency while providing desirable implementation size and heat dissipation characteristics.

[0081] FIG. 6 shows the PMC 612 coupled only with the baseband circuitry 604. However, in other embodiments, the PMC 612 may be additionally or alternatively coupled with, and perform similar power management operations for, other components such as, but not limited to, the application circuitry 602, the RF circuitry 606, or the FEM circuitry 608.

[0082] In some embodiments, the PMC 612 may control, or otherwise be part of, various power saving mechanisms of the device 600. For example, if the device 600 is in an RRC_Connected state, where it is still connected to the RAN node as it expects to receive traffic shortly, then it may enter a state known as Discontinuous Reception Mode (DRX) after a period of inactivity. During this state, the device 600 may power down for brief intervals of time and thus save power.

[0083] If there is no data traffic activity for an extended period of time, then the device 600 may transition off to an RRCJdle state, where it disconnects from the network and does not perform operations such as channel quality feedback, handover, etc. The device 600 goes into a very low power state and it performs paging where again it periodically wakes up to listen to the network and then powers down again. The device 600 may not receive data in this state, and in order to receive data, it transitions back to an RRC_Connected state.

[0084] An additional power saving mode may allow a device to be unavailable to the network for periods longer than a paging interval (ranging from seconds to a few hours). During this time, the device is totally unreachable to the network and may power down completely. Any data sent during this time incurs a large delay and it is assumed the delay is acceptable.

[0085] Processors of the application circuitry 602 and processors of the baseband circuitry 604 may be used to execute elements of one or more instances of a protocol stack. For example, processors of the baseband circuitry 604, alone or in combination, may be used to execute Layer 3, Layer 2, or Layer 1 functionality, while processors of the application circuitry 602 may utilize data (e.g., packet data) received from these layers and further execute Layer 4 functionality (e.g.,

transmission communication protocol (TCP) and user datagram protocol (UDP) layers). As referred to herein, Layer 3 may comprise a radio resource control (RRC) layer, described in further detail below. As referred to herein, Layer 2 may comprise a medium access control layer (MAC), a radio link control (RLC) layer, and a packet data convergence protocol (PDCP) layer, described in further detail below. As referred to herein, Layer 1 may comprise a physical (PHY) layer of a UE/RAN node, described in further detail below.

[0086] FIG. 7 illustrates example interfaces of baseband circuitry in accordance with some embodiments. As discussed above, the baseband circuitry 604 of FIG. 6 may comprise processors 604A-604E and a memory 604G utilized by said processors. Each of the processors 604A-604E may include a memory interface, 704A-704E, respectively, to send/receive data to/from the memory 604G.

[0087] The baseband circuitry 604 may further include one or more interfaces to communicatively couple to other circuitries/devices, such as a memory interface 712 (e.g., an interface to send/receive data to/from memory external to the baseband circuitry 604), an application circuitry interface 714 (e.g., an interface to send/receive data to/from the application circuitry 602 of FIG. 6), an RF circuitry interface 716 (e.g., an interface to send/receive data to/from RF circuitry 606 of FIG. 6), a wireless hardware connectivity interface 718 (e.g., an interface to send/receive data to/from Near Field Communication (NFC) components, Bluetooth® components (e.g., Bluetooth® Low Energy), Wi-Fi® components, and other communication

components), and a power management interface 720 (e.g., an interface to send/receive power or control signals to/from the PMC 612.

[0088] FIG. 8 is an illustration of a control plane protocol stack in accordance with some embodiments. In this embodiment, a control plane 800 is shown as a communications protocol stack between the UE 501 (or alternatively, the UE 502), the RAN node 51 1 (or alternatively, the RAN node 512), and the MME 521.

[0089] A PHY layer 801 may transmit or receive information used by the MAC layer 802 over one or more air interfaces. The PHY layer 801 may further perform link adaptation or adaptive modulation and coding (AMC), power control, cell search (e.g., for initial synchronization and handover purposes), and other measurements used by higher layers, such as an RRC layer 805. The PHY layer 801 may still further perform error detection on the transport channels, forward error correction (FEC) coding/decoding of the transport channels, modulation/demodulation of physical channels, interleaving, rate matching, mapping onto physical channels, and Multiple Input Multiple Output (MIMO) antenna processing.

[0090] The MAC layer 802 may perform mapping between logical channels and transport channels, multiplexing of MAC service data units (SDUs) from one or more logical channels onto transport blocks (TB) to be delivered to PHY via transport channels, de-multiplexing MAC SDUs to one or more logical channels from transport blocks (TB) delivered from the PHY via transport channels, multiplexing MAC SDUs onto TBs, scheduling information reporting, error correction through hybrid automatic repeat request (HARQ), and logical channel prioritization.

[0091] An RLC layer 803 may operate in a plurality of modes of operation, including: Transparent Mode (TM), Unacknowledged Mode (UM), and Acknowledged Mode (AM). The RLC layer 803 may execute transfer of upper layer protocol data units (PDUs), error correction through automatic repeat request (ARQ) for AM data transfers, and concatenation, segmentation and reassembly of RLC SDUs for UM and AM data transfers. The RLC layer 803 may also execute re-segmentation of RLC data PDUs for AM data transfers, reorder RLC data PDUs for UM and AM data transfers, detect duplicate data for UM and AM data transfers, discard RLC SDUs for UM and AM data transfers, detect protocol errors for AM data transfers, and perform RLC re-establishment.

[0092] A PDCP layer 804 may execute header compression and decompression of IP data, maintain PDCP Sequence Numbers (SNs), perform in-sequence delivery of upper layer PDUs at re-establishment of lower layers, eliminate duplicates of lower layer SDUs at re-establishment of lower layers for radio bearers mapped on RLC AM, cipher and decipher control plane data, perform integrity protection and integrity verification of control plane data, control timer-based discard of data, and perform security operations (e.g., ciphering, deciphering, integrity protection, integrity verification, etc.).

[0093] The main services and functions of the RRC layer 805 may include broadcast of system information (e.g., included in Master Information Blocks (MIBs) or System Information Blocks (SIBs) related to the non-access stratum (NAS)), broadcast of system information related to the access stratum (AS), paging, establishment, maintenance and release of an RRC connection between the UE and E-UTRAN (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), establishment, configuration, maintenance and release of point-to-point radio bearers, security functions including key management, inter radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting. Said MIBs and SIBs may comprise one or more information elements (lEs), which may each comprise individual data fields or data structures.

[0094] The UE 501 and the RAN node 51 1 may utilize a Uu interface (e.g., an LTE-Uu interface) to exchange control plane data via a protocol stack comprising the PHY layer 801 , the MAC layer 802, the RLC layer 803, the PDCP layer 804, and the RRC layer 805.

[0095] In the embodiment shown, the non-access stratum (NAS) protocols 806 form the highest stratum of the control plane between the UE 501 and the MME 521 . The NAS protocols 806 support the mobility of the UE 501 and the session management procedures to establish and maintain IP connectivity between the UE 501 and the P-GW 523.

[0096] The S1 Application Protocol (S1 -AP) layer 815 may support the functions of the S1 interface and comprise Elementary Procedures (EPs). An EP is a unit of interaction between the RAN node 51 1 and the CN 520. The S1 -AP layer services may comprise two groups: UE-associated services and non UE-associated services. These services perform functions including, but not limited to: E-UTRAN Radio Access Bearer (E-RAB) management, UE capability indication, mobility, NAS signaling transport, RAN Information Management (RIM), and configuration transfer.

[0097] The Stream Control Transmission Protocol (SCTP) layer (alternatively referred to as the stream control transmission protocol/internet protocol (SCTP/IP) layer) 814 may ensure reliable delivery of signaling messages between the RAN node 51 1 and the MME 521 based, in part, on the IP protocol, supported by an IP layer 813. An L2 layer 812 and an L1 layer 81 1 may refer to communication links (e.g., wired or wireless) used by the RAN node and the MME to exchange

information. [0098] The RAN node 51 1 and the MME 521 may utilize an S1 -MME interface to exchange control plane data via a protocol stack comprising the L1 layer 81 1 , the L2 layer 812, the IP layer 813, the SCTP layer 814, and the S1 -AP layer 815.

[0099] FIG. 9 is a block diagram illustrating components, according to some example embodiments, able to read instructions from a machine-readable or computer-readable medium (e.g., a non-transitory machine-readable storage medium) and perform any one or more of the methodologies discussed herein.

Specifically, FIG. 9 shows a diagrammatic representation of hardware resources 900 including one or more processors (or processor cores) 910, one or more

memory/storage devices 920, and one or more communication resources 930, each of which may be communicatively coupled via a bus 940. For embodiments where node virtualization (e.g., NFV) is utilized, a hypervisor 902 may be executed to provide an execution environment for one or more network slices/sub-slices to utilize the hardware resources 900.

[0100] The processors 910 (e.g., a central processing unit (CPU), a reduced instruction set computing (RISC) processor, a complex instruction set computing (CISC) processor, a graphics processing unit (GPU), a digital signal processor (DSP) such as a baseband processor, an application specific integrated circuit (ASIC), a radio-frequency integrated circuit (RFIC), another processor, or any suitable combination thereof) may include, for example, a processor 912 and a processor 914.

[0101] The memory/storage devices 920 may include main memory, disk storage, or any suitable combination thereof. The memory/storage devices 920 may include, but are not limited to any type of volatile or non-volatile memory such as dynamic random access memory (DRAM), static random-access memory (SRAM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), Flash memory, solid-state storage, etc.

[0102] The communication resources 930 may include interconnection or network interface components or other suitable devices to communicate with one or more peripheral devices 904 or one or more databases 906 via a network 908. For example, the communication resources 930 may include wired communication components (e.g., for coupling via a Universal Serial Bus (USB)), cellular

communication components, NFC components, Bluetooth® components (e.g., Bluetooth® Low Energy), Wi-Fi® components, and other communication components.

[0103] Instructions 950 may comprise software, a program, an application, an applet, an app, or other executable code for causing at least any of the processors 910 to perform any one or more of the methodologies discussed herein. The instructions 950 may reside, completely or partially, within at least one of the processors 910 (e.g., within the processor's cache memory), the memory/storage devices 920, or any suitable combination thereof. Furthermore, any portion of the instructions 950 may be transferred to the hardware resources 900 from any combination of the peripheral devices 904 or the databases 906. Accordingly, the memory of processors 910, the memory/storage devices 920, the peripheral devices 904, and the databases 906 are examples of computer-readable and machine- readable media.

Examples

[0104] The following examples pertain to further embodiments.

[0105] Example 1 is a New Radio (NR) base station for providing a set of user equipment (UEs) access to a fifth generation (5G) core network, comprising a set of distributed units (DUs), a central unit (CU), and a MAC-PHY. The set of DUs, each comprising a physical layer (PHY) entity and configured to communicate with a subset of the UEs using a wireless cellular channel. The CU in communication with the set of distributed units, comprising a medium access control layer (MAC) entity configured to provide centralized scheduling for PHYs of the set of DUs. The MAC- PHY interface, configured to enable communication between the DUs and the CU.

[0106] Example 2 is the system of Example 1 , wherein the MAC entity is further configured for multiplexing and demultiplexing between transport channels and logical channels.

[0107] Example 3 is the system of Example 1 , wherein the CU further comprises a controller configured to provide the interface between the MAC entity and the set of DUs.

[0108] Example 4 is the system of Example 3, wherein the controller is

configured to map unique MAC entity identifiers and PHY entity identifiers during interface establishment. [0109] Example 5 is the system of any of Examples 1 -4, wherein the CU further comprises a radio link control layer (RLC) entity, a packet data convergence protocol (PDCP) entity and a radio resource control (RRC) entity.

[0110] Example 6 is the system of any of Examples 1 -4, wherein the processor is a baseband processor.

[0111] Example 7 is an apparatus of a central unit (CU) of a radio access network (RAN) node, comprising a medium access control layer (MAC), a MAC-PHY interface, a controller. The MAC entity configured to provide centralized scheduling to a set of DUs, each DU comprising a physical layer (PHY) entity and configured to communicate with a subset of user equipment (UEs) using a wireless cellular channel. The MAC-PHY interface, configured to enable communication between the DUs and the CU; and the controller configured to route communications between the MAC entity and the PHY entities using the MAC-PHY interface.

[0112] Example 8 is the apparatus of Example 7, wherein the controller is configured to map unique MAC entity identifiers and PHY entity identifiers during interface establishment of a PHY from a DU from the set of DUs with the MAC entity.

[0113] Example 9 is the apparatus of Example 7, wherein the controller is configured to provide mapping of messages between legacy transport channels and legacy physical channels.

[0114] Example 10 is the apparatus of Example 7, wherein the controller is configured to update a transport network characteristic of a PHY entity from a DU from the set of DUs and provide the updated transport network characteristic of the PHY to the MAC entity.

[0115] Example 1 1 is the apparatus of any of Examples 7-10, wherein the MAC entity adds a DU to the set of DUs based on an addition request or setup request.

[0116] Example 12 is the system of any of Examples 7-10, wherein the processor is a baseband processor.

[0117] Example 13 is a method of establishing a medium access control layer (MAC)-physical layer (PHY) communication link between a central unit (CU) and a distributed unit (DU), the method comprising: establishing, by a controller, a MAC- PHY communication channel between the controller of the CU and a PHY entity in the DU; determining a unique MAC entity identifier and a unique PHY entity identifier based at least in part on the mapping in-between through the interface

establishment; appending a header that identifies a source identifier and a destination identifier, the source identifier including the unique PHY entity identifier and the destination identifier including the unique MAC entity identifier; and routing messages, by the MAC entity, based at least in part on the unique MAC entity identifier or the unique PHY entity identifier.

[0118] Example 14 is the method of Example 13, wherein the establishing the MAC-PHY communication channel further comprises message exchanges such as MAC-PHY SETUP REQUEST, MAC-PHY SETUP RESPONSE or MAC-PHY

SETUP FAILURE for the interface establishment.

[0119] Example 15 is the method of Example 13, wherein the method further comprises providing the mapping of the messages between the legacy transport channels and the legacy physical channels in both DL and UL directions.

[0120] Example 16 is the method of Example 13, wherein the method further comprises periodically providing transport network characteristics that are measured.

[0121] Example 17 is an apparatus comprising means to perform a method as exemplified in any of Examples 13-16.

[0122] Example 18 is a machine-readable storage including machine-readable instructions, when executed, to implement a method or realize an apparatus as exemplified in any of Examples 13-16.

[0123] Example 19 is a machine readable medium including code, when executed, to cause a machine to perform the method of any one of Examples 13-16.

[0124] Example 20 is a computer program product comprising a computer- readable storage medium that stores instructions for execution by a processor to perform operations of a central unit (CU), the operations, when executed by the processor, to perform a method, the method comprising: establishing, by a controller, a MAC-PHY communication channel between the controller of the CU and a PHY entity in the DU; determining a unique MAC entity identifier and a unique PHY entity identifier based at least in part on the mapping in-between through the interface establishment; appending a header that identifies a source identifier and a

destination identifier, the source identifier including the unique PHY entity identifier and the destination identifier including the unique MAC entity identifier; and routing messages, by the MAC entity, based at least in part on the unique MAC entity identifier or the unique PHY entity identifier.

[0125] Example 21 is the computer program product of Example 20, wherein the establishing the MAC-PHY communication channel further comprises message exchanges such as MAC-PHY SETUP REQUEST, MAC-PHY SETUP RESPONSE or MAC-PHY SETUP FAILURE for the interface establishment.

[0126] Example 22 is a central unit (CU) comprising: means for establishing, by a controller, a MAC-PHY communication channel between the controller of the CU and a PHY entity in the DU; means for determining a unique MAC entity identifier and a unique PHY entity identifier based at least in part on the mapping in-between through the interface establishment; means for appending a header that identifies a source identifier and a destination identifier, the source identifier including the unique PHY entity identifier and the destination identifier including the unique MAC entity identifier; and means for routing messages, by the MAC entity, based at least in part on the unique MAC entity identifier or the unique PHY entity identifier.

Additional Examples

[0127] Additional Example 1 is an Evolved Node B (eNB) or new RAT radio access network architecture (next generation RAN) comprising: a central unit (CU) with the lowest protocol stack of the controller and one or more MAC entity(ies) interacting with upper layers such as RLC, PDCP, RRC, etc.; one or more distributed unit(s) (DU), each with the highest protocol stacks of the PHY entity(ies) interacting with lower layers such as RF component, etc.; and one or more interfaces between the controller and the one or more PHY entity(ies), nested under the transport network interface between the CU and the DU(s).

[0128] Additional Example 2 is the eNB of Additional Example 1 , wherein the transport network characteristic comprises available BW and/or latency of the physical mediums connecting CU and each DU.

[0129] Additional Example 3 is the eNB of Additional Example 1 , wherein a MAC entity in the CU performs centralized scheduling decisions for multiple PHY entities in one or more DUs.

[0130] Additional Example 4 is the eNB of Additional Example 1 , wherein a MAC entity in the CU considers the transport network characteristic between the CU and the DU(s) and the processing capability of each PHY entity and/or each DU when deciding the centralized scheduling.

[0131] Additional Example 5 is the eNB of Additional Example 1 , wherein a MAC entity in the CU retrieves and delivers, through the interface, the scheduling-related information and user data regarding the associated PHY and RF components. [0132] Additional Example 6 is the eNB of Additional Example 1 , wherein the controller determines unique MAC entity and PHY entity identifiers, mapping in- between through the interface establishment.

[0133] Additional Example 7 is the eNB of Additional Example 1 , wherein the controller provides mapping of any messages between legacy transport channels and legacy physical channels in both DL and UL directions.

[0134] Additional Example 8 is the eNB of Additional Example 1 , wherein the controller appends a header comprising source and/or destination identifiers, and performs routing of the information delivered through the interface.

[0135] Embodiments and implementations of the systems and methods described herein may include various operations, which may be embodied in machine- executable instructions to be executed by a computer system. A computer system may include one or more general-purpose or special-purpose computers (or other electronic devices). The computer system may include hardware components that include specific logic for performing the operations or may include a combination of hardware, software, and/or firmware.

[0136] Computer systems and the computers in a computer system may be connected via a network. Suitable networks for configuration and/or use as described herein include one or more local area networks, wide area networks, metropolitan area networks, and/or Internet or IP networks, such as the World Wide Web, a private Internet, a secure Internet, a value-added network, a virtual private network, an extranet, an intranet, or even stand-alone machines which communicate with other machines by physical transport of media. In particular, a suitable network may be formed from parts or entireties of two or more other networks, including networks using disparate hardware and network communication technologies.

[0137] One suitable network includes a server and one or more clients; other suitable networks may contain other combinations of servers, clients, and/or peer-to- peer nodes, and a given computer system may function both as a client and as a server. Each network includes at least two computers or computer systems, such as the server and/or clients. A computer system may include a workstation, laptop computer, disconnectable mobile computer, server, mainframe, cluster, so-called "network computer" or "thin client," tablet, smart phone, personal digital assistant or other hand-held computing device, "smart" consumer electronics device or appliance, medical device, or a combination thereof. [0138] Suitable networks may include communications or networking software, such as the software available from Novell®, Microsoft®, and other vendors, and may operate using TCP/IP, SPX, IPX, and other protocols over twisted pair, coaxial, or optical fiber cables, telephone lines, radio waves, satellites, microwave relays, modulated AC power lines, physical media transfer, and/or other data transmission "wires" known to those of skill in the art. The network may encompass smaller networks and/or be connectable to other networks through a gateway or similar mechanism.

[0139] Various techniques, or certain aspects or portions thereof, may take the form of program code (i.e., instructions) embodied in tangible media, such as floppy diskettes, CD-ROMs, hard drives, magnetic or optical cards, solid-state memory devices, a nontransitory computer-readable storage medium, or any other machine- readable storage medium wherein, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the various techniques. In the case of program code execution on programmable computers, the computing device may include a processor, a storage medium readable by the processor (including volatile and nonvolatile memory and/or storage elements), at least one input device, and at least one output device. The volatile and nonvolatile memory and/or storage elements may be a RAM, an

EPROM, a flash drive, an optical drive, a magnetic hard drive, or other medium for storing electronic data. The eNB (or other base station) and UE (or other mobile station) may also include a transceiver component, a counter component, a processing component, and/or a clock component or timer component. One or more programs that may implement or utilize the various techniques described herein may use an application programming interface (API), reusable controls, and the like. Such programs may be implemented in a high-level procedural or an object-oriented programming language to communicate with a computer system. However, the program(s) may be implemented in assembly or machine language, if desired. In any case, the language may be a compiled or interpreted language, and combined with hardware implementations.

[0140] Each computer system includes one or more processors and/or memory; computer systems may also include various input devices and/or output devices. The processor may include a general purpose device, such as an Intel®, AMD®, or other "off-the-shelf" microprocessor. The processor may include a special purpose processing device, such as ASIC, SoC, SiP, FPGA, PAL, PLA, FPLA, PLD, or other customized or programmable device. The memory may include static RAM, dynamic RAM, flash memory, one or more flip-flops, ROM, CD-ROM, DVD, disk, tape, or magnetic, optical, or other computer storage medium. The input device(s) may include a keyboard, mouse, touch screen, light pen, tablet, microphone, sensor, or other hardware with accompanying firmware and/or software. The output device(s) may include a monitor or other display, printer, speech or text synthesizer, switch, signal line, or other hardware with accompanying firmware and/or software.

[0141] It should be understood that many of the functional units described in this specification may be implemented as one or more components, which is a term used to more particularly emphasize their implementation independence. For example, a component may be implemented as a hardware circuit comprising custom very large scale integration (VLSI) circuits or gate arrays, or off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A component may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices, or the like.

[0142] Components may also be implemented in software for execution by various types of processors. An identified component of executable code may, for instance, comprise one or more physical or logical blocks of computer instructions, which may, for instance, be organized as an object, a procedure, or a function.

Nevertheless, the executables of an identified component need not be physically located together, but may comprise disparate instructions stored in different locations that, when joined logically together, comprise the component and achieve the stated purpose for the component.

[0143] Indeed, a component of executable code may be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices.

Similarly, operational data may be identified and illustrated herein within

components, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network. The components may be passive or active, including agents operable to perform desired functions. [0144] Several aspects of the embodiments described will be illustrated as software modules or components. As used herein, a software module or component may include any type of computer instruction or computer-executable code located within a memory device. A software module may, for instance, include one or more physical or logical blocks of computer instructions, which may be organized as a routine, program, object, component, data structure, etc., that perform one or more tasks or implement particular data types. It is appreciated that a software module may be implemented in hardware and/or firmware instead of or in addition to software. One or more of the functional modules described herein may be separated into sub-modules and/or combined into a single or smaller number of modules.

[0145] In certain embodiments, a particular software module may include disparate instructions stored in different locations of a memory device, different memory devices, or different computers, which together implement the described functionality of the module. Indeed, a module may include a single instruction or many instructions, and may be distributed over several different code segments, among different programs, and across several memory devices. Some

embodiments may be practiced in a distributed computing environment where tasks are performed by a remote processing device linked through a communications network. In a distributed computing environment, software modules may be located in local and/or remote memory storage devices. In addition, data being tied or rendered together in a database record may be resident in the same memory device, or across several memory devices, and may be linked together in fields of a record in a database across a network.

[0146] Reference throughout this specification to "an example" means that a particular feature, structure, or characteristic described in connection with the example is included in at least one embodiment. Thus, appearances of the phrase "in an example" in various places throughout this specification are not necessarily all referring to the same embodiment.

[0147] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on its presentation in a common group without indications to the contrary. In addition, various embodiments and examples may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations.

[0148] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of materials, frequencies, sizes, lengths, widths, shapes, etc., to provide a thorough

understanding of the embodiments. One skilled in the relevant art will recognize, however, that the embodiments may be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well- known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of embodiments.

[0149] It should be recognized that the systems described herein include descriptions of specific embodiments. These embodiments can be combined into single systems, partially combined into other systems, split into multiple systems or divided or combined in other ways. In addition, it is contemplated that

parameters/attributes/aspects/etc. of one embodiment can be used in another embodiment. The parameters/attributes/aspects /etc. are merely described in one or more embodiments for clarity, and it is recognized that the

parameters/attributes/aspects /etc. can be combined with or substituted for parameters/attributes/etc. of another embodiment unless specifically disclaimed herein.

[0150] Although the foregoing has been described in some detail for purposes of clarity, it will be apparent that certain changes and modifications may be made without departing from the principles thereof. It should be noted that there are many alternative ways of implementing both the processes and apparatuses described herein. Accordingly, the present embodiments are to be considered illustrative and not restrictive, and the description is not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims.

[0151] It will be obvious to those having skill in the art that many changes may be made to the details of the above-described embodiments without departing from the underlying principles. The scope of the present embodiments should, therefore, be determined only by the following claims.

Claims

Claims

1 . A New Radio (NR) base station for providing a set of user equipment (UEs) access to a fifth generation (5G) core network, comprising:

a set of distributed units (DUs), each comprising a physical layer (PHY) entity and configured to communicate with a subset of the UEs using a wireless cellular channel;

a central unit (CU) in communication with the set of distributed units, comprising a medium access control layer (MAC) entity configured to provide centralized scheduling for PHYs of the set of DUs; and

a MAC-PHY interface, configured to enable communication between the DUs and the CU.

2. The system of claim 1 , wherein the MAC entity is further configured for multiplexing and demultiplexing between transport channels and logical channels.

3. The system of claim 1 , wherein the CU further comprises a controller configured to provide the interface between the MAC entity and the set of DUs.

4. The system of claim 3, wherein the controller is configured to map unique MAC entity identifiers and PHY entity identifiers during interface establishment.

5. The system of any of claims 1 -4, wherein the CU further comprises a radio link control layer (RLC) entity, a packet data convergence protocol (PDCP) entity and a radio resource control (RRC) entity.

6. The system of any of claims 1 -4, wherein the processor is a baseband processor.

7. An apparatus of a central unit (CU) of a radio access network (RAN) node, comprising:

a medium access control layer (MAC) entity configured to provide centralized scheduling to a set of distributed units (DUs), each DU comprising a physical layer (PHY) entity and configured to communicate with a subset of user equipment (UEs) using a wireless cellular channel;

a MAC-PHY interface, configured to enable communication between the DUs and the CU; and

a controller configured to route communications between the MAC entity and the PHY entities using the MAC-PHY interface.

8. The apparatus of claim 7, wherein the controller is configured to map unique MAC entity identifiers and PHY entity identifiers during interface

establishment of a PHY from a DU from the set of DUs with the MAC entity.

9. The apparatus of claim 7, wherein the controller is configured to provide mapping of messages between legacy transport channels and legacy physical channels.

10. The apparatus of claim 7, wherein the controller is configured to update a transport network characteristic of a PHY entity from a DU from the set of DUs and provide the updated transport network characteristic of the PHY to the MAC entity.

1 1 . The apparatus of any of claims 7-10, wherein the MAC entity adds a DU to the set of DUs based on an addition request or setup request.

12. The system of any of claims 7-10, wherein the processor is a baseband processor.

13. A method of establishing a medium access control layer (MAC)-physical layer (PHY) communication link between a central unit (CU) and a distributed unit (DU), the method comprising:

establishing, by a controller, a MAC-PHY communication channel between the controller of the CU and a PHY entity in the DU;

determining a unique MAC entity identifier and a unique PHY entity identifier based at least in part on the mapping in-between through the interface

establishment;

appending a header that identifies a source identifier and a destination identifier, the source identifier including the unique PHY entity identifier and the destination identifier including the unique MAC entity identifier; and

routing messages, by the MAC entity, based at least in part on the unique MAC entity identifier or the unique PHY entity identifier.

14. The method of claim 13, wherein the establishing the MAC-PHY communication channel further comprises message exchanges such as MAC-PHY SETUP REQUEST, MAC-PHY SETUP RESPONSE or MAC-PHY SETUP FAILURE for the interface establishment.

15. The method of claim 13, wherein the method further comprises providing the mapping of the messages between the legacy transport channels and the legacy physical channels in both DL and UL directions.

16. The method of claim 13, wherein the method further comprises

periodically providing transport network characteristics that are measured.

17. An apparatus comprising means to perform a method as claimed in any of claims 13-16.

18. Machine-readable storage including machine-readable instructions, when executed, to implement a method or realize an apparatus as claimed in any of claims 13-16.

19. A machine readable medium including code, when executed, to cause a machine to perform the method of any one of claims 13-16.