WO2019014907A1

WO2019014907A1 - Systems and methods for robust random access configurations

Info

Publication number: WO2019014907A1
Application number: PCT/CN2017/093757
Authority: WO
Inventors: Junfeng Zhang; Peng Hao
Original assignee: Zte Corporation
Priority date: 2017-07-20
Filing date: 2017-07-20
Publication date: 2019-01-24
Also published as: CN110999448A

Abstract

A system and method for random access is disclosed. In one embodiment, a method performed by a first communication node includes: receiving a plurality of downlink signals from a second communication node; identifying a plurality of logical resources, each of the plurality of logical resources associated with a respective one of the plurality of downlink signals; determining, for each set of M logical resources, N physical random access channel (PRACH) resources, where M and N are positive integers; and transmitting an uplink signal, wherein the uplink signal uses N PRACH resources to transmit M preambles.

Description

SYSTEMS AND METHODS FOR ROBUST RANDOM ACCESS CONFIGURATIONS

TECHNICAL FIELD

This disclosure relates generally to wireless communications and, more particularly, to systems and methods for random access.

BACKGROUND

Fifth generation new radio communication systems (e.g.， 5G NR) may be implemented in a higher and wider frequency band (e.g.， above 3GHz) in order to achieve a higher data rate than previous generation communication systems. However, high frequency communications may be characterized by more significant channel loss and penetration loss during transmission of electromagnetic waves in air (e.g.， radio signals) at such high frequencies. Due to the shorter wavelength of higher frequency signals, a large number of small antenna arrays may be used to enable beamforming technologies to obtain more accurate beam directions. This narrow beam technique may improve the coverage of high frequency signals and compensate for transmission loss, which may be one of the major causes of failures in communication systems at such high frequencies.

Accordingly, factors that need to be considered in the configuration of random access resources in previous generation communication systems may be less complicated than that in 5G NR. For example, multiple random access resources in 5G NR may be transmitted at different frequencies and multiplexed in the same time domain. Also, the type of timeslot (e.g., a slot) used for random access in 5G NR is not fixed. For example, a slot may be used only for uplink, or for both downlink and uplink. Also, slots may be differentiated when utilized for downlink (DL) or for uplink (UP) . Also, the ratio of time domain resources between uplink and downlink slots may also vary. Variations of this ratio may result in semi-static or, alternatively, dynamic adjustments of resource allocations.

Beams may be widely used in 5G NR. Therefore, beam configurations may affect resource allocations for random access. For example, resource allocations in 5G NR may take into account configurations such as the number of transmitting/receiving beams and the beam reciprocity of a base station (BS) and user equipment (UE) .

Multiple random access preamble formats may be standardized in 5G NR. For example, a preamble may use traditional subcarrier spacing of 1.25 KHz as part of a preamble format for a long sequence. Also, a preamble may use a subcarrier spacing (SCS) of values such as 15, 30, 60, and 120 KHz, for a preamble format of a short sequence. These preambles may be scaled in accordance with a particular SCS. For example, when scaling a preamble format for a preamble of a short sequence, resource indication in the time domain using a fixed reference time (e.g., 1 millisecond in a subframe) may be difficult. Therefore, reference times for different subcarriers may scale according to the timeslot (e.g.， slot) length of subcarriers with varying subcarrier spacing.

In 5G NR, preamble formats may be determined based on purpose. For example, particular preamble formats for particular preambles may be used for beam scanning. Other preamble formats may be used for coverage enhancement in 5G NR. Having preambles be formatted for different purposes may complicate preambles in 5G NR, but may also allocate resources more effectively and flexibility than previous generation communication systems which may use the same preamble for different purposes.

Also, random-access configuration signals in 5G NR may include a predetermined index mapping between synchronization blocks (SSB) and random-access resources. This index mapping scheme may be used to determine use of random access resources in the time-frequency domain. Accordingly, random access resources and configurations corresponding to a particular downlink signal may be identified by this index mapping scheme.

However, as random access resources in 5G NR evolve to become increasingly complex and sophisticated, traditional determinations of random access resources in 5G NR may not provide be entirely satisfactory.

SUMMARY OF THE INVENTION

The exemplary embodiments disclosed herein are directed to solving the issues relating to one or more of the problems presented in the prior art, as well as providing additional features that will become readily apparent by reference to the following detailed description when taken in conjunction with the accompany drawings. In accordance with various embodiments, exemplary systems, methods, devices and computer program products are disclosed herein. It is understood, however, that these embodiments are presented by way of example and not limitation, and it will be apparent to those of ordinary skill in the art who read the present disclosure that various modifications to the disclosed embodiments can be made while remaining within the scope of the invention.

In one embodiment, a method performed by a first communication node includes: receiving a plurality of downlink signals from a second communication node； identifying a plurality of logical resources, each of the plurality of logical resources associated with a respective one of the plurality of downlink signals； determining, for each set of M logical resources, N physical random access channel (PRACH) resources, where M and N are positive integers； and transmitting an uplink signal, wherein the uplink signal uses N PRACH resources to transmit M preambles.

In a further embodiment, a method performed by a first communication node includes: sending a plurality of downlink signals to a second communication node； receiving an uplink signal from the second communication node； decoding M preambles from N PRACH resources from the uplink signal, the M preambles identifying M downlink signals of the plurality of downlink signals, wherein M and N are positive integers； and transmitting a random access response referencing at least one of the M preambles to the second communication node.

In another embodiment, a first communication node includes: a receiver configured to: receive a plurality of downlink signals from a second communication node, and identify a plurality of logical resources, each of the plurality of logical resources associated with a respective one of the plurality of downlink signals； at least one processor configured to: determine, for each set of M logical resources, N physical random access channel (PRACH) resources, where M and N are positive integers； and a transmitter configured to: transmit an uplink signal, wherein the uplink signal uses N PRACH resources to transmit M preambles.

In yet another embodiment, a first communication node includes: a transmitter configured to: send a plurality of downlink signals to a second communication node； a receiver configured to: receive an uplink signal from the second communication node； at least one processor configured to: decode M preambles from N PRACH resources from the uplink signal, the M preambles identifying M downlink signals of the plurality of downlink signals, wherein M and N are positive integers, wherein the transmitted is configured to transmit a random access response referencing at least one of the M preambles to the second communication node.

BRIEF DESCRIPTION OF THE DRAWINGS

Various exemplary embodiments of the invention are described in detail below with reference to the following Figures. The drawings are provided for purposes of illustration only and merely depict exemplary embodiments of the invention to facilitate the reader's understanding of the invention. Therefore, the drawings should not be considered limiting of the breadth, scope, or applicability of the invention. It should be noted that for clarity and ease of illustration these drawings are not necessarily drawn to scale.

Figure 1 illustrates an exemplary cellular communication network in which techniques disclosed herein may be implemented, in accordance with various embodiments of the present disclosure.

Figure 2 is a block diagram that illustrates an exemplary base station and user equipment device, in accordance with some embodiments of the invention.

Figure 3 is a block diagram that illustrates of how multiple random access channel (RACH) groups may be transmitted in a period, in accordance with some embodiments of the invention.

Figure 4 is a block diagram that illustrates how multiple RACH groups may be differentiated across frequencies, in accordance with some embodiments of the invention.

Figures 5A is a block diagram that illustrates a downlink centric slot, in accordance with some embodiments of the invention.

Figure 5B is a block diagram that illustrates an uplink centric slot, in accordance with some embodiments of the invention.

Figure 6 is a block diagram that illustrates relationships between synchronization blocks (SSB) , occasions, and slots in a 1: 1 relationship, in accordance with some embodiments.

Figure 7 is a block diagram that illustrates relationships between synchronization blocks (SSB) , occasions, and slots in a one-to-many relationship, in accordance with some embodiments.

Figure 8 is a block diagram that illustrates relationships between synchronization blocks (SSB) , occasions, and slots in a many-to-one relationship, in accordance with some embodiments.

Figure 9 is a block diagram that illustrates preamble format repetition when performing coverage enhancement, in accordance with some embodiments.

Figure 10 is a block diagram that illustrates RACH blocks 1002, in accordance with some embodiments.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Various exemplary embodiments of the invention are described below with reference to the accompanying figures to enable a person of ordinary skill in the art to make and use the invention. As would be apparent to those of ordinary skill in the art, after reading the present disclosure, various changes or modifications to the examples described herein can be made without departing from the scope of the invention. Thus, the present invention is not limited to the exemplary embodiments and applications described and illustrated herein. Additionally, the specific order or hierarchy of steps in the methods disclosed herein are merely exemplary approaches. Based upon design preferences, the specific order or hierarchy of steps of the disclosed methods or processes can be re-arranged while remaining within the scope of the present invention. Thus, those of ordinary skill in the art will understand that the methods and techniques disclosed herein present various steps or acts in a sample order, and the invention is not limited to the specific order or hierarchy presented unless expressly stated otherwise.

Figure 1 illustrates an exemplary wireless communication network 100 in which techniques disclosed herein may be implemented, in accordance with an embodiment of the present disclosure. The exemplary communication network 100 includes a base station (BS) 102 and a user equipment (UE) device 104 that can communicate with each other via a communication link 110 (e.g.， a wireless communication channel) , and a cluster of

notional cells

126, 130, 132, 134, 136, 138 and 140 overlaying a geographical area 101. In Figure 1, the BS 102 and UE 104 are contained within the geographic boundary of cell 126. Each of the

other cells

130, 132, 134, 136, 138 and 140 may include at least one base station (BS) operating at its allocated bandwidth to provide adequate radio coverage to its intended users. For example, the BS 102 may operate at an allocated channel transmission bandwidth to provide adequate coverage to the UE 104. The BS 102 and the UE 104 may communicate via a downlink radio frame 118, and an uplink radio frame 124 respectively. Each radio frame 118/124 may be further divided into sub-frames 120/127 which may include data symbols 122/128. In the present disclosure, the base station (BS) 102 and user equipment (UE) 104 are described herein as non-limiting examples of “communication nodes, ” generally, which can practice the methods disclosed herein. Such communication nodes may be capable of wireless and/or wired communications, in accordance with various embodiments of the invention.

As described below, functional entities, such as UE, BS, etc. (either in physical or virtual form) , may be similar to those mentioned above with respect to conventional networks. As would be understood by persons of ordinary skill in the art, however, such conventional functional entities do not perform the functions described below, and therefore, would need to be modified or specifically configured to perform one or more of the operations described below. Additionally, persons of skill in the art would be enabled to configure functional entities to perform the operations described herein after reading the present disclosure. The term “configured” as used herein with respect to a specified operation or function refers to a system, device, component, circuit, structure, machine, etc. that is physically or virtually constructed, programmed and/or arranged to perform the specified operation or function.

In network 100, a signal transmitted from the BS 102 may suffer from the environmental and/or operating conditions that cause undesirable channel characteristics, such as Doppler spread, Doppler shift, delay spread, multipath interference, etc. mentioned above. For example, multipath signal components may occur as a consequence of reflections, scattering, and diffraction of the transmitted signal by natural and/or man-made objects. At the receiver antenna 114, a multitude of signals may arrive from many different directions with different delays, attenuations, and phases. Generally, the time difference between the arrival moment of a first received multipath component (typically the line of sight (LOS) component) and the last received multipath component (typically a non-line of sigh (NLOS) component) is called delay spread. The combination of signals with various delays, attenuations, and phases may create distortions such as inter-symbol interference (ISI) and inter-channel interference (ICI) in the received signal. The distortion may complicate reception and conversion of the received signal into useful information. For example, delay spread may cause ISI in the useful information (data symbols) contained in the radio frame 124.

Figure 2 is a block diagram that illustrates an exemplary system 200 including a base station (BS) 202 and user equipment (UE) 204 for transmitting and receiving wireless communication signals, e.g.， OFDM/OFDMA signals, between each other. The system 200 may include components and elements configured to support known or conventional operating features that need not be described in detail herein. In one exemplary embodiment, system 200 can be used to transmit and receive data symbols in a wireless communication environment such as the wireless communication environment 100 of Figure 1, as described above.

The BS 202 includes a BS transceiver module 210, a BS antenna 212, a BS processor module 214, a BS memory module 216, and a network communication module 218, each module being coupled and interconnected with one another as necessary via a data communication bus 220. The UE 204 includes a UE transceiver module 230, a UE antenna 232, a UE memory module 234, and a UE processor module 236, each module being coupled and interconnected with one another as necessary via a data communication bus 240. The BS 202 communicates with the UE 204 via a communication channel (e.g.， link) 250, which can be any wireless channel or other medium known in the art suitable for transmission of data as described herein.

As would be understood by persons of ordinary skill in the art, system 200 may further include any number of modules other than the modules shown in Figure 2. Those skilled in the art will understand that the various illustrative blocks, modules, circuits, and processing logic described in connection with the embodiments disclosed herein may be implemented in hardware, computer-readable software, firmware, or any practical combination thereof. To clearly illustrate this interchangeability and compatibility of hardware, firmware, and software, various illustrative components, blocks, modules, circuits, and steps are described generally in terms of their functionality. Whether such functionality is implemented as hardware, firmware, or software depends upon the particular application and design constraints imposed on the overall system. Those familiar with the concepts described herein may implement such functionality in a suitable manner for each particular application, but such implementation decisions should not be interpreted as limiting the scope of the present invention.

In accordance with some embodiments, UE transceiver 230 may be referred to herein as an "uplink" transceiver 230 that includes a RF transmitter and receiver circuitry that are each coupled to the antenna 232. A duplex switch (not shown) may alternatively couple the uplink transmitter or receiver to the uplink antenna in time duplex fashion. Similarly, in accordance with some embodiments, the BS transceiver 210 may be referred to herein as a "downlink" transceiver 210 that includes RF transmitter and receiver circuity that are each coupled to the antenna 212. A downlink duplex switch may alternatively couple the downlink transmitter or receiver to the downlink antenna 212 in time duplex fashion. The operations of the two

transceivers

210 and 230 are coordinated in time such that the uplink receiver is coupled to the uplink antenna 232 for reception of transmissions over the wireless transmission link 250 at the same time that the downlink transmitter is coupled to the downlink antenna 212. Preferably there is close time synchronization with only a minimal guard time between changes in duplex direction.

The UE transceiver 230 and the base station transceiver 210 are configured to communicate via the wireless data communication link 250, and cooperate with a suitably configured RF antenna arrangement 212/232 that can support a particular wireless communication protocol and modulation scheme. In some exemplary embodiments, the UE transceiver 230 and the base station transceiver 210 are configured to support industry standards such as the Long Term Evolution (LTE) and emerging 5G and New Radio (NR) standards, and the like. It is understood, however, that the invention is not necessarily limited in application to a particular standard and associated protocols. Rather, the UE transceiver 230 and the base station transceiver 210 may be configured to support alternate, or additional, wireless data communication protocols, including future standards or variations thereof.

In accordance with various embodiments, the BS 202 may be a next generation nodeB (gNodeB or gNB) , serving gNB, target gNB, transmission reception point (TRP) , evolved node B (eNB) , a serving eNB, a target eNB, a femto station, or a pico station, for example. In some embodiments, the UE 204 may be embodied in various types of user devices such as a mobile phone, a smart phone, a personal digital assistant (PDA) , tablet, laptop computer, wearable computing device, etc. The

processor modules

214 and 236 may be implemented, or realized, with a general purpose processor, a content addressable memory, a digital signal processor, an application specific integrated circuit, a field programmable gate array, any suitable programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein. In this manner, a processor may be realized as a microprocessor, a controller, a microcontroller, a state machine, or the like. A processor may also be implemented as a combination of computing devices, e.g.， a combination of a digital signal processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other such configuration.

Furthermore, the steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in firmware, in a software module executed by

processor modules

214 and 236, respectively, or in any practical combination thereof. The

memory modules

216 and 234 may be realized as RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. In this regard,

memory modules

216 and 234 may be coupled to the

processor modules

214 and 236, respectively, such that the

processors modules

214 and 236 can read information from, and write information to,

memory modules

216 and 234, respectively. The

memory modules

216 and 234 may also be integrated into their

respective processor modules

214 and 236. In some embodiments, the

memory modules

216 and 234 may each include a cache memory for storing temporary variables or other intermediate information during execution of instructions to be executed by

processor modules

214 and 236, respectively.

Memory modules

216 and 234 may also each include non-volatile memory for storing instructions to be executed by the

processor modules

214 and 236, respectively.

The network communication module 218 generally represents the hardware, software, firmware, processing logic, and/or other components of the base station 202 that enable bi-directional communication between base station transceiver 210 and other network components and communication nodes configured to communication with the base station 202. For example, network communication module 218 may be configured to support internet or WiMAX traffic. In a typical deployment, without limitation, network communication module 218 provides an 802.3 Ethernet interface such that base station transceiver 210 can communicate with a conventional Ethernet based computer network. In this manner, the network communication module 218 may include a physical interface for connection to the computer network (e.g.， Mobile Switching Center (MSC) ) .

In order to meet the performance requirements of International Mobile Telecommunications (IMT) -Advanced systems, the LTE/LTE-Advanced standards have offered several features to optimize radio networks in the frequency, time and/or spatial domains. With the continuing evolutions of wireless technologies, it is expected that future radio access networks will be able to support the explosive growth of wireless traffic. Among these features, widening the system bandwidth is one straightforward way to improve the link and system capacity, which is already being tested and confirmed by the deployment of carrier aggregation in LTE-Advanced systems.

As the demand for capacity increases, mobile industries as well as academia have become more interested in increasing system bandwidths to greater than 100 MHz. Additionally, because spectrum resources operating below a frequency of 6 GHz have become more congested, high-frequency communications above 6GHz are well-suited to support system bandwidths of more than 100 MHz, or even up to 1 GHz.

In some embodiments, communications between a base station and a UE are implemented with signal frequencies greater than 6 GHz, which are also called “millimeter wave communications. ” When using wide or ultra wide spectrum resources, however, a considerable propagation loss can be induced by high operating frequencies (i.e.， greater than 6 GHz) . To solve this, antenna array (e.g.， panel array) and beamforming (BF) training technologies using Massive MIMO, e.g.， 1024 antenna elements for one node, have been adopted to achieve beam alignment and obtain sufficiently high antenna gain. To keep implementation costs down while benefiting from antenna array technologies, analog phase shifters have become attractive for implementing mm wave beam forming (BF) , which means that the number of phases is finite and other constraints (e.g.， amplitude constraints) can be placed on the antenna elements to provide variable-phase-shift based BF. Given such pre-specified beam patterns, e.g.， the antenna weight vector (AWV) codebook, the variable-phase-shift-based BF training targets to identify the best-N beams, for subsequent data transmission can be determined.

A misalignment between transmit (Tx) and receive (Rx) beams may cause a significant loss in the received power, especially for systems with narrow beams. Beam alignment may be used to find the best beam pair from all possible beam pairs for maximum beamforming efficiency. The best beam pair may be determined by selecting a beam pair with the maximum array gain. Random access is may be used to initiate communications and alignment between a UE and BS. For example, in random access, preambles may be a type of random access resource transmitted/received repeatedly in multiple directions from the UEs and BSs to synchronize and align the UE and BS. Individual Tx beams may be transmitted by the UE until all of the transmission (Tx) beams are transmitted. An receiver (Rx) beam sweep may be performed at the BS for each Tx beam to measure the signal-to-noise ratio (SNR) for every Tx-Rx pair.

Random access is generally performed when a UE turns on from sleep mode, performs a handover from one cell to another, or loses uplink time synchronization. As part of random access, a UE may receive synchronization signals and/or reference signals from a BS. These synchronization signals and/or reference signals may instruct the UE as to how to communicate with the BS in random access. Based on the information in the synchronization signals and/or reference signals, the UE may transmit a preamble to the BS. When the BS successfully receives the preamble, the BS may send to the UE a random access response indicating a preamble index, uplink timing advance (TA) , and uplink resource-allocation information. Based on the random access response, the UE can determine whether its random access attempt has been successful by matching the preamble index to the preamble that the UE sent to the BS. If there is a match, the UE may use the TA information to adjust its uplink timing and transmit a random access message including the UE’s identity in the resource allocation in accordance with the uplink resource-allocation information.

Systems and methods in accordance with various embodiments may describe robust configurations of random access resources. Random access resources may include physical random access channel (PRACH) resources and logical resources used in random access. PRACH resources may be any type of resource utilized for random access in the time domain, frequency domain, and/or the code domain. These PRACH resources may reflect basic units for configuration of physical resources associated with random access (such as synchronization blocks, RACH blocks, slots, and frequency values) and will be discussed in further detail below. Logical resources may be any type of meaning or organization of PRACH resources (e.g., a particular configuration or use of PRACH resources) . Stated another way, a PRACH resource may relate to, or configure, basic units of physical resources that are related to random access. Also, logical resources may relate to, or configure, units of PRACH resources. For example, logical resources may describe a configuration (e.g.， relationship) of logical resources and/or PRACH resources. These logical resources, as configurations of PRACH resources, may represent RACH groups, RACH occasions, and the like. Logical resources may also include identifiers such as a preamble, index value, and/or downlink identifier. In certain embodiments, logical resources may include a mapping (that may be represented in a table) that relates various logical resources and/or PRACH resources to each other. For example, a mapping may describe what preambles are related to which downlink signals. Indexes values may be utilized as identifiers or proxies during mapping to more easily identify the various specific PRACH resources and/or logical resources with each other. PRACH resources and logical resources will be discussed in further detail below.

In certain embodiments, random access timeslots (also termed more simply as a slot) may a PRACH resource in the time domain that may be configured to relate to (e.g.， map to) certain logical resources. For example, slots may be encoded (e.g.， configured) with logical resources (e.g.， a RACH occasion) , such as in accordance with a one-to-one, one-to-many, and many-to-one relationship, as will be discussed further below.

Accordingly, robust random access configurations may include various logical resources that cross reference physical random access channel (PRACH) resources with each other and other logical resources. For example, a logical resource may relate a downlink signal with a preamble, and/or a RACH occasion, as discussed further below.

Furthermore, certain logical resources may be utilized, or not utilized based upon different applications in various embodiments. For example, a separate RACH group index may not be utilized as a proxy (e.g.， an identifier between) a downlink signal and RACH group when the downlink signal and the RACH group may uniquely identify each other (e.g.， without need to reference the RACH group index) . Stated another way, the RACH group (as a logical resource data structure that characterizes a particular configuration of PRACH resources in the time domain, frequency domain, and code domain) may be sufficiently unique itself to be an identifier of a downlink signal without a need to separately reference a RACH group index value. These logical resources, and their relations to PRACH resources, may be utilized by a UE and/or a BS to configure signals between the UE and BS for random access.

As introduced above, random access resources may include PRACH resources and logical resources. These random access resources may include: RACH blocks, RACH bursts, RACH burst sets, RACH time instances, RACH occasions, and RACH groups. A RACH block, as a PRACH resource, may be a smallest unit of a time domain resource. In certain embodiments, a RACH block (as a PRACH resource) may be encoded with a preamble (a logical resource) . In particular embodiments, a RACH block may be equivalent to a RACH time instance.

A RACH burst may be a collection of multiple RACH blocks. The RACH blocks may be continuously or discontinuously connected in a RACH burst. Similar to RACH blocks, a RACH burst may be a PRACH resource in the time domain. RACH blocks may be discontinuously connected when they are part of slots that are transmitted intermittently (as opposed to across a continuous transmission of slots) . As an example, a single RACH burst may characterize a complete beam scan to a BS (e.g.， as a UE’s transmission of a RACH MSG1) . However, in certain embodiments, a single RACH block may also characterize a complete beam scan if the beam scan does not need to be broken up into separate components that are each to be characterized in individual RACH blocks. Also a complete beam scan may be characterized in a single RACH block (e.g.， as an acknowledgement signal) if beams of a BS and UE are reciprocal.

A RACH group may be a random access resource across the time-frequency-code domains. Stated another way, a RACH group may be a complete characterization of a random access signal (e.g.， a downlink signal and/or an uplink signal) , or a beam, across the time domain, frequency domain, and the code domain. For example, each beam used in communications between a UE and a BS may be characterized by a RACH group across the time domain, frequency domain, and the code domain. Accordingly, each of the receiving beams at a BS may be characterized by a RACH group. In certain embodiments, RACH groups may include repeated resources in the time, frequency, and/or code domains. Also, when beams are reciprocal (e.g.， where a best beam pair in a downlink is the same as the best beam pair for an uplink) RACH groups may not need to be determined separately for a downlink and/or an uplink.

A RACH group characterized in the time domain may be a RACH burst. RACH bursts are discussed above. Also, a RACH occasion may be a RACH group in the time domain and in the frequency domain. RACH occasions will be discussed further below.

A RACH burst set may be a set of multiple RACH groups. For example, a RACH burst set may characterize every available beam for a downlink and/or for an uplink between a UE and a BS as a set of multiple RACH groups.

An index may be an identifier of a particular random access resource or a configuration of random access resources. For example, a RACH group index may include index values (e.g.， identifiers within the context of the RACH group index) of a particular RACH group (e.g.， configuration of resources across time, frequency, and code domains) . In certain embodiments, a BS may determine a relationship between a RACH group index and other resources, such as by relating particular RACH group index values to downlink signals, preambles or other random access resources or indexes for other random access resources. This relationship may be indicated (e.g.， transmitted) to a UE from a BS or to a BS from a UE. For example, In response to transmitting a downlink signal to a UE, a BS may receive an uplink signal from the UE that includes a RACH group, a RACH group index value, a preamble, or other type of information that may identify the downlink signal sent from the BS and received by the UE.

As introduced above, logical resources may include mapping relationships between various random access resources. For example, a mapping relationship may relate indexes for resources in various domains (e.g.， a time-frequency domain) to resources in the same or other domains (e.g.， slots or other resources in a time domain) .

In certain embodiments, PRACH resources, such as slots, may be encoded (e.g., configured) with logical resources (e.g.， information, such as a RACH occasion, identifier or a preamble) , in accordance with a one-to-one (e.g.， 1: 1) , one-to-many (1: many) , and/or many-to-one (many: 1) mapping relationships. The one-to-one relationship refers to one logical resource (e.g.， RACH group) per one PRACH resource (e.g.， slot) . The one-to-many relationship refers to one logical resource (e.g.， RACH group) encoded across multiple PRACH resources (e.g.， slots) . The many-to-one relationship refers to many logical resources (e.g.， RACH group) encoded across a single PRACH resource (e.g.， slot) . These mapping relationships will be discussed further below.

Each of the above discussed random access resources may have particular configurations that may be expressed (e.g.， identified) as different index values. These configurations may also be termed as parameters. In certain embodiments, these index values may be actual measurable values associated with a particular random axis resource. In other embodiments, these index values may be arbitrary and not necessarily related to a measurable value of a random access resource. These parameters may define the columns in a table, where a particular column is related to a parameter (or random access resource in a column) and different configurations of that particular parameter may be expressed as different index values across the particular column. Illustrative examples of such tables are provided below with Table 1 and Table 2. Accordingly, the various configurations of random access resources (as parameters) may be cross reference table horizontally across different columns (e.g.， across a single row) . Examples of different random access resources that may be parameters include: a preamble format, timeslot format, formats for physical resources in the time-frequency domain for random access (e.g.， configurations of the RACH group in the time-frequency domain) , RACH group code allocations (e.g.， code domain aspects of a RACH group) , number of available downlink signals, RACH period, number of RACH groups in a RACH time occasion, frequency domain random access resource configurations, time domain random access resource configurations, and the like. Further discussion of these parameters are provided below.

A preamble format may refer to formatting for a preamble. For example, preamble formats may refer to various configurations of subcarrier spacing, symbol length, symbol repetition number, preamble format repetition number (e.g.， and number of preamble repetitions) , cyclic prefix (CP) length, and guard period (GP) length.

A timeslot format configurations may refer to a type of slot and vary between whether a slot (e.g.， a TDD (time division duplex) slot) is for uplink, downlink, or a combination of (e.g., a ratio of) uplink and downlink usage. Stated another way, the types of slots used for random access may not be fixed and may be variable. For example, a slot used in uplink, which can be a TDD slot, may provide most or all of the slot’s resource for random access. Also, a slot may be also used for both downlink and uplink, where slots used in uplink can be used to provide resources for random access. As another example, slots may be downlink centric and/or uplink centric. As yet another example, the ratio between a quantity of slots used for uplink, as opposed to downlink (or vice versa) may vary at different times. This may result in a dynamic adjustment of an amount of time domain resources used in uplink and/or downlink during random access.

Formats for physical resources in the time-frequency domain for random access may refer to various configurations (and associated index values) for physical resources in the time-frequency domain. In certain embodiments, these various index values may be associated with time domain and/or frequency domain aspects of a RACH group or a RACH burst set (e.g., a set of RACH groups) . For example, a RACH group index value of 0 may correspond to a time-frequency resource index value of 0, a RACH group index value of 1 may correspond to a time-frequency resource index value of 1, and so on.

In some embodiments, it may not be necessary for index values to express every possible configuration of random access resources. For example, it may not be necessary to associate all RACH groups in the time-frequency domain with index values (and/or other logical resources) in order to uniquely identify the RACH groups in the time-frequency domain. Rather, PRACH resources and/or RACH groups may be identified uniquely if there is a defined relationship with other random access resources which may act as a proxy for a RACH group index. For example, a RACH group in the time-frequency domain may be uniquely identified individually based upon a unique combination of the indexes for the RACH group in both the time domain (e.g.， an index value for a RACH burst) and in the frequency domain (e.g.， an index value for the frequency aspect of a RACH group) . Also, index values may be assigned in accordance with a particular rule that defines a calculable relationship between a PRACH resource and an index value (as opposed to index values being arbitrarily assigned to PRACH resources) . Additionally, index values may be assigned that relate to measurable aspects of a PRACH resource. Further examples of how relationships between random access resources may be inferred from other random access resources, rather than being explicitly assigned or arbitrary designated, may be contemplated in accordance with various embodiments. For example, in certain embodiments, relationships between logical resources in the time-frequency domain may be derived from a unique configurations of the RACH preamble format, timeslot format, the physical resource of random access in the time-frequency domain, and the range or the number of the resource in the code domain (e.g.， RACH group code allocations) , and the like. For example, a particular RACH preamble format may be used to uniquely identify a particular DL beam without need for assigning an index value for the particular RACH preamble format and relating that additional index value to the DL beam. These types of inferences, or derivations of relationships between random access resources may be advantageous as it may not be practical to have an infinite number of index values. For example, only a certain amount of index values may be stored in memory and therefore reducing the amount of index values may free up processing resources for tasks other than storage of unnecessary index values.

A number of downlink signals may refer to a measurable number of downlink signals. The number of downlink signals may be a parameter that may be cross referenced with other random access parameters, such as a preamble.

A RACH group code allocation may be a parameter that describes (e.g.， identifies) a range of possible codes (e.g.， code domain resources) . These code group allocations may be associated with a RACH group. For example, a code domain aspect of a RACH group may include a range of possible codes that may be associated with a RACH group in a code domain. In certain embodiments, each RACH group may include at least one code domain resource. In other embodiments, RACH groups may include multiple code domain resources to avoid collisions between random access signals (by differentiating between the signals in the code domain with unique code domain resources) .

A RACH period (e.g.， a period of a RACH Group) describes the number of RACH groups after which the same RACH group may appear again. For example, if a period is equal to 1, identical RACH group may appear at every RACH group. When a period is four, identical RACH groups may appear after every fourth RACH group.

A number of RACH groups in a RACH time occasion may refer to how many RACH groups may be associated with a particular amount of time. For example, a single time period may be associated with multiple RACH groups (as the time domain resources of the RACH group may fall within the single time period) .

Time domain random access resource configurations may refer to various configurations of random access resources (e.g.， slot lengths) represented in the time domain. Different from LTE in which random access resource in the time domain is a subframe, a random access resource in the time domain in 5G NR may be slot (e.g.， timeslot) . These slots may scale with subcarrier spacing. Stated another way, subcarriers with different spacing have different slot lengths. For example, for a subcarrier spacing of 15 KHz, the slot length may be 1 ms. Also, for a subcarrier spacing of 120 KHz, the slot length may be 0.125 ms.

Frequency domain random access resource configurations may refer to various configurations of random access resources represented in the frequency domain. For example, frequency domain configurations may reflect a starting frequency of a bandwidth and/or an index value for the frequency domain aspect of RACH group. In certain embodiments, a bandwidth may be dependent upon other random access resource configurations. For example, bandwidth may be directly related to subcarrier spacing, where a downlink bandwidth of 2.16 MHz may be associated with a subcarrier spacing of 30 KHz.

In certain embodiments, subcarrier spacing may be a parameter with variations identified by a particular set of indexes (e.g.， index values) that may be cross referenced with index values from other random access resources. These subcarrier spacing index values may be part of a subcarrier spacing index that may be cross referenced with other parameters such as a downlink signal index, preamble format repetition number, block index, and/or the resource index in the frequency domain. A downlink signal may refer to a synchronization signal or a reference signal and a downlink signal index may be an index that identifies different downlink signals. A preamble format repetition number may be a number of symbol repetitions in a preamble format, as will be discussed further below in connection with Figure 9. A block index may be an index for that identifies various blocks (e.g.， RACH blocks) . In certain embodiments, these various blocks may be part of a slot. Also, in particular embodiments, these blocks may include a starting block from which a random access signal is transmitted. A frequency resource index may be an index of a random access resource in the frequency domain, as discussed above.

Logical resources, such as indexes, may be mapped (e.g.， related) to each other and/or to PRACH resources. In certain embodiments, RACH groups and downlink signals may each be identified by respective indexes. These index values for the RACH groups and downlink signals may be mapped together and cross referenced. For example, an index value for a first downlink signal may be 0. This downlink signal index value of 0 may be associated with a RACH group index value of 0. Similarly, a downlink signal index value of 1 may be associated with a RACH group index value of 1, and so on. Although index values in certain embodiments may appear to have a sequential order (e.g.， 0, 1, 2, 3, and so on) , in other embodiments index values may be assigned in a random order and may not necessarily be sequential (e.g.， 0, 5, 2, -1, 100, and so on) .

In certain embodiments, index mapping may be represented as a table that maps particular index values to other index values. An example of such a table is given in Table 1, below:

Downlink signal index	RACH group index
0	0, 1
1	2, 3
2	3, 4
3	5, 6

Table 1: Index mapping of downlink signal index values to RACH group index values

As illustrated in Table 1, various downlink signal index values may be related to various RACH group index values. Also, a single downlink signal index value may be related to multiple RACH group index values. Stated another way, multiple RACH group index values may overlap with a single downlink signal index value. In certain embodiments where a single index value is desired for selection from multiple index values, a single index value out of the possible multiple indexes values may be randomly selected.

Table 1 may reflect an embodiment where there are four independent downlink signals that may each be identified by either of two RACH groups. The downlink signals may be transmitted from a transmission node with an analog or a mixed beamforming capability (e.g., digital and/or analog) . The two RACH groups associated with a single downlink signal index may be differentiated in any of a time, frequency, and/or code domain. For example, each of the two RACH groups associated with a single downlink index may be differentiated in the time domain and/or in the code domain.

Figure 3 is a block diagram that illustrates how multiple RACH groups 302A-304B may be in a RACH period 310, in accordance with some embodiments of the invention. Within the RACH period 310, each of the RACH groups 302A-304B may be differentiated along the time domain and along the code domain. For example, RACH group 302A may be differentiated from RACH group 302B along the code domain (e.g.， by being associated with different codes) . Also, RACH group 302A may be differentiated from RACH group 304A along the time domain (e.g.， by being associated with a particular slot, or other time domain resource) .

The RACH groups 302A-304B may repeat in other RACH periods 314. In certain embodiments, the RACH groups 302A-304B may be utilized to identify four independent downlink signals. For example, RACH group 302A may be associated with a first downlink signal, RACH group 302B may be associated with a second downlink signal, RACH group 304A may be associated with a third downlink signal, and RACH group 304B may be associated with a fourth downlink signal. In particular embodiments, these downlink signals may be produced by digital beamforming.

Figure 4 is a block diagram that illustrates how multiple RACH groups 402A-404B across RACH periods 415A-415E may be differentiated in three different domains, in accordance with some embodiments of the invention. Each of the RACH groups 402A-404B may be differentiated along the frequency domain, the time domain, and the code domain with RACH groups within a given RACH period and RACH groups outside of the given RACH period. For example, RACH group 402A may be differentiated from RACH group 402B along the code domain (e.g.， by being associated with different codes) . Also, a RACH group 402A within a given RACH period (e.g.， RACH period 415A) may be differentiated from another RACH group 402A within a different RACH period (e.g.， RACH period 415B) along the time domain (e.g.， by being associated with a particular slot, or other time domain resource) . Furthermore, RACH group 402A may be differentiated from RACH group 404A along the frequency domain (e.g.， by being associated with different frequency domain resources) .

The RACH groups 402A-404B may repeat in each of the RACH periods 415A-415E. In certain embodiments, the RACH groups 402A-404B may be utilized to identify four independent downlink signals. For example, RACH group 402A may be associated with a first downlink signal, RACH group 402B may be associated with a second downlink signal, RACH group 404A may be associated with a third downlink signal, and RACH group 404B may be associated with a fourth downlink signal. In particular embodiments, these downlink signals may be produced by digital beamforming. Each of these RACH groups may be associated with respective individual index values. In certain embodiments, each RACH group may utilize half of the random access resources in the code domain.

As introduced above, slots may be differentiated as uplink centric or downlink centric. Figure 5A is a block diagram that illustrates a downlink centric slot 502, in accordance with some embodiments of the invention. The downlink centric slot may have more time domain resources available for symbols related to downlink than for uplink. The downlink centric slot may be utilized in accordance with time domain duplex (TDD) communications. For example, the downlink centric slot 502 may include 14 symbols, two for a downlink control channel 504 and eight for synchronization blocks (SSB) 506. The remaining four symbols may be allocated for a guard period 508, a RACH 510 (e.g.， PRACH resources) and a physical uplink control channel (PUCCH) 512. The RACH 510 and the PUCCH 512 may be used for uplink 514. Accordingly, of the 14 symbols, the majority of the symbols (e.g.， 10 symbols) may be utilized for downlink communications.

Figure 5B is a block diagram that illustrates an uplink centric slot 552, in accordance with some embodiments of the invention. The uplink centric slot 552 may have more time domain resources available for symbols related to uplink than for downlink. The uplink centric slot 552 may be utilized in accordance with time domain duplex (TDD) communications. For example, the uplink centric slot 552 may include 14 symbols. Ten of the 14 symbols may be associated with uplink communications 554, with 8 symbols reserved for a RACH 556 (e.g., PRACH resources) and two symbols reserved for a PUCCH 558. The remaining symbols may be reserved for a DLC 560 and a guard period 562. Accordingly, of the 14 symbols, the majority of the symbols (e.g.， ten symbols) may be utilized for uplink communications. Also, as illustrated in Figures 5A and 5B, PRACH resources may be transmitted independent of the type of slot (e.g.， downlink centric slot or uplink centric slot) .

As introduced above, PRACH resources, such as slots, may be encoded (e.g., configured) with logical resources (e.g.， RACH occasions) , in accordance with a one-to-one (e.g., 1: 1) , one-to-many (1: many) , and/or many-to-one (many: 1) mapping relationships. The one-to- one relationship refers to one logical resource (e.g.， RACH occasion) per one PRACH resource (e.g.， slot) . Figure 6 is a block diagram that illustrates relationships between synchronization blocks (SSB) , RACH occasions, and slots in a one-to-one relationship, in accordance with some embodiments. Communications between a UE and a BS may be represented across the time domain as a collection of synchronization blocks 602, which may be of synchronization bursts 604, which may be of synchronization burst sets 606. As introduced above, synchronization blocks 602 may be a basic time domain unit and may be associated with a slot 608 that may be correspondingly transmitted during the time domain resources reserved for the synchronization block 602. Slots 608 may be associated with a RACH occasion 610 (e.g.， a time-frequency domain aspect of a RACH group) . Accordingly, a synchronization block 602 may correspond (e.g.， have equivalent respective time domain resources) as a RACH occasion 610, and a slot 608. Stated another way, the RACH occasion 610 may have a one-to-one relationship with the slot 608 as the single RACH occasion 610 may correspond to (e.g.， map to) a single slot 608.

As introduced above, the RACH occasion 610 may provide a resource in the time-frequency domain within which a scan of the UE’s uplink signal can be completed by all the receiving beams of the BS. Stated another way, the RACH occasion 610 may be a time-frequency representation a RACH group that may correspond to a single beam, or all beams between a UE and BS in a beam scan. In some embodiments, a RACH occasion 610 includes 8 symbols, which may express a complete random access preamble format (e.g.， is a preamble) . In further embodiments, each symbol may be the same (e.g.， be repeated symbols) to reduce the chance of an erroneous reception or decoding of RACH occasion 610 in the slot 608.

Figure 7 is a block diagram that illustrates relationships between synchronization blocks (SSB) , RACH occasions, and slots in a one-to-many relationship, in accordance with some embodiments. As discussed above, communications between a UE and a BS may be represented across the time domain as a collection of

synchronization blocks

702A and 702B, which may be part of a synchronization burst 704, which may be part of a synchronization burst set 706. Each synchronization signal 702 may be associated with a

particular slot

708A and 708B.

Multiple slots

708A and 708B, may be associated with a single RACH occasion 710 (e.g., a time-frequency domain aspect of a RACH group) . Accordingly, the RACH occasion 710 may have a one-to-many relationship with the slot 608 as the single RACH occasion 710 may correspond to multiple (e.g.， two)

slots

708A and 708B.

Each

slot

708A and 708B may have eight symbols. Also, the RACH occasion may have 16 symbols. In certain embodiments, the RACH occasion may represent a preamble. The symbols in each

slot

708A and 708B may be configured in accordance with a preamble format (e.g.， the combination of the symbols in the

slots

708A and 708B may represent the preamble of the RACH occasion) . In certain embodiments, the same preamble format may be repeated twice, once in each

slot

708A and 708B. Accordingly, the BS may perform training and detection on 16 receiving beams (e.g.， one for each symbol associated with the RACH occasion) . Also,

slots

708A and 708B may be transmitted continuously in certain embodiments or may be transmitted discontinuously in other embodiments as desired for different applications. In some embodiments, there may be less than 14 receiving beams (e.g.， 12 receiving beams) on the BS. For example, the BS may be configured to perform beam sweeping on less than 14 (e.g., 12) receiving beams, or may be configured to decode less than 14 (e.g.， 12) symbols. When there are less than 14 receiving beams, the remaining RACH symbols (e.g.， 4) not associated with the receiving beams may still be formatted in accordance with a preamble format but may not be used for beam sweeping at a BS. Stated another way, a single RACH occasion may correspond to more than one slot, but may not need to utilize all symbols available across all of the more than one slots. Accordingly, certain unused symbols in the slots may not need to be decoded.

Figure 8 is a block diagram that illustrates relationships between synchronization blocks (SSB) , RACH occasions, and slots in a many-to-one relationship, in accordance with some embodiments. As discussed above, communications between a UE and a BS may be represented across the time domain as a collection of

synchronization blocks

802A and 802B. The synchronization blocks 802A and 802B may be part of a synchronization burst 804. The synchronization burst 804 may be part of a synchronization burst set 806. Each synchronization signal 802 may be associated with a

particular slot

808A and 808B. Each

slot

808A and 808B may be associated with multiple RACH occasions 810A-810D (e.g.， a time-frequency domain aspect of a RACH group) . For example, slot 808A may be associated with RACH occasions 810A and 810B. Also, slot 808B may be associated with

RACH occasions

810C and 810D. Accordingly, the RACH occasions 810A-810D may have a many-to-one relationship with the

slots

808A and 808B, such that two RACH occasions (e.g.， RACH occasions 810A and 810B) may be associated with a single slot (e.g.， slot 808A) .

In certain embodiments, each

slot

808A and 808B may include 8 symbols, for a total of 16 symbols across both

slots

808A and 808B. These symbols may be part of a sequence for random access (e.g.， be part of a preamble) . Four of the symbols in each

slot

808A and 808B may be associated with a particular RACH occasion 810A-810D. Also, in certain embodiments, each of the RACH occasions 810A-810D may include a single symbol that is repeated four times. By repeating the single symbol four times, a receiving BS may train in on and detect the repeated symbol with more accuracy as the receiving BS may have four opportunities to correctly decode the single symbol. Each opportunity to decode the single symbol may be performed using a receiving beam of the BS. In particular embodiments, if there is a cascade of multiple RACH occasions associated with a single slot (e.g.， when one slot includes multiple RACH occasions) , a cyclic prefix may be inserted between each of the RACH occasions represented in each respective slot.

The above discussed mapping situations (e.g.， one-to-one, one-to-many and many-to-one) logical resources (e.g.， RACH occasions) and physical resources for random access (e.g., slots) may apply when the BS does not include reciprocal beams. In certain embodiments, the relationship between each of the random access resources (e.g.， RACH occasions to slots) may be predetermined. For example, specific configuration between RACH preamble formats and slots introduced above (e.g.， combining multiple preambles in a single slot for random access) can be pre-determined. Furthermore, as introduced above, various relationships between random access resources may be predetermined. Examples of relationships that may be predetermined include relationships between a logical resource (e.g.， RACH occasion in the time-frequency domain) with different preamble formats (which may vary by subcarrier spacing, symbol length, symbol repetition number, number of preamble repetitions, etc. ) , timeslot format (which may vary by being uplink centric or downlink centric) , physical resources in the time-frequency domain for random access, and RACH group code allocations.

In certain embodiments, index mapping (e.g.， between a downlink signal and a logical resource such as a RACH occasion or a RACH group) may not be directly mapped, but may rely on an intermediate parameter such as a RACH group index. However, in other embodiments, intermediate parameters, such as a RACH group index, may not be necessary to describe a relationship between random access resources. For example, the specific configuration of a RACH group may be sufficiently unique to identify a downlink signal without requiring that each RACH group be given a separate RACH group index value as an intermediate parameter value.

In certain embodiments, a data structure, such as a table, may be utilized to represent relationships between various random access resources. An example of such a table is provided below as Table 2:

Table 2: Random Access Resource Relationships

Table 2 assumes that the format of the random access timeslot (e.g.， slots) does not vary dynamically during one period. Table 2 may be a type of index mapping table. The left side of the index mapping table includes the physical random access channel (PRACH) configuration index. The PRACH configuration index may be associated (e.g.， be cross referenceable with) a number of parameters (e.g.， random access resources referenced in the columns) , such as a preamble format (e.g.， RACH preamble format) , system frame number, and slot number. In certain embodiments, the PRACH configuration index value may be equivalent to a RACH group index value

With reference to Table 2, preamble format repetition may refer to a number of repetitions of a RACH preamble format (e.g.， number of repetitions of a preamble) . Preamble format repetition is to fulfill the receiving beam sweeping at base station, or may be performed as part of coverage enhancement. Coverage enhancement may be a random access process where random access resources (e.g.， symbols) are repeated in order to improve the accuracy of signal (or symbol) reception. Figure 9 is a block diagram that illustrates preamble format repetition when performing receiving beam sweeping or coverage enhancement, in accordance with some embodiments. One preamble, formatted in accordance with a preamble format, may be repeated twice in a RACH occasion 902. Each repeated preamble may be carried in two slots 904A and 904B, where each of the two slots 904A and 904B includes a copy of the same preamble.

With reference to Table 2, block index may refer to a index value ascribed to individual RACH blocks in a single slot. In certain embodiments, a RACH block may include a preamble format and there may be multiple RACH blocks in a single slot. Stated another way, RACH blocks may describe how preambles (formatted in accordance with a preamble format) may multiplex into a single slot for random access in the time domain. Each RACH block may be ascribed with an index value. For example, for a slot with at least two RACH blocks, a first RACH block may be ascribed with an index value of 0, a second RACH block may be ascribed with an index value of 1, and so on. The number of RACH blocks associated with a slot may depend on the size of a slot and the specific preamble format of a preamble.

Figure 10 is a block diagram that illustrates RACH blocks 1002, in accordance with some embodiments. Each RACH block 1002 may correspond to a RACH occasion 1004 and include a preamble formatted in accordance with a preamble format. Also, each slot 1006 may include multiple (e.g.， two) RACH blocks 1002.

With reference to Table 2, a preamble group index may refer to a particular grouping of preambles. For example, in embodiments where there may be 64 total preambles, “whole” refers to any of the 64 preambles, first half may refer to any of the first 32 preambles, and second half may refer to any of the last 32 preambles. As discussed above, preambles may be utilized as identifiers, such as an identifier for a cell. In certain embodiments, numbers may be utilized to represent the preamble group index, such as 0 for all indexes, 1 for the first half, 2 for the second half, 3 for the first quarter, and so on. In particular embodiments, a preamble group index may be used as cross reference to various random access resources (e.g.， random access resources in the time-frequency domain) .

With reference to Table 2, a frequency resource index may refer to a frequency domain resource of a random access signal. For example, each index value of the frequency resource index may refer to a particular type, or combination, of frequency values.

With reference to Table 2, a downlink signal index may be an index for downlink signals. These downlink signals may be synchronization signals (e.g.， signals that carry synchronization blocks) or reference signals (e.g.， channel state information reference signals (CSI-RS) ) . In certain embodiments, different downlink signal indexes and their corresponding random access resources (of the respective downlink signal) may be orthogonal in the frequency domain. In certain embodiments, multiple downlink signal indexes may be associated (e.g., correspond with) a same random access resource. For example, more than one downlink signal index value may be associated with a single PRACH configuration index value (e.g.， at PRACH configuration index values 6-7 in Table 2) .

While various embodiments of the invention have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. Likewise, the various diagrams may depict an example architectural or configuration, which are provided to enable persons of ordinary skill in the art to understand exemplary features and functions of the invention. Such persons would understand, however, that the invention is not restricted to the illustrated example architectures or configurations, but can be implemented using a variety of alternative architectures and configurations. Additionally, as would be understood by persons of ordinary skill in the art, one or more features of one embodiment can be combined with one or more features of another embodiment described herein. Thus, the breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments.

It is also understood that any reference to an element herein using a designation such as "first, " "second, " and so forth does not generally limit the quantity or order of those elements. Rather, these designations can be used herein as a convenient means of distinguishing between two or more elements or instances of an element. Thus, a reference to first and second elements does not mean that only two elements can be employed, or that the first element must precede the second element in some manner.

Additionally, a person having ordinary skill in the art would understand that information and signals can be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits and symbols, for example, which may be referenced in the above description can be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

A person of ordinary skill in the art would further appreciate that any of the various illustrative logical blocks, modules, processors, means, circuits, methods and functions described in connection with the aspects disclosed herein can be implemented by electronic hardware (e.g., a digital implementation, an analog implementation, or a combination of the two) , firmware, various forms of program or design code incorporating instructions (which can be referred to herein, for convenience, as "software" or a "software module) , or any combination of these techniques.

To clearly illustrate this interchangeability of hardware, firmware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware, firmware or software, or a combination of these techniques, depends upon the particular application and design constraints imposed on the overall system. Skilled artisans can implement the described functionality in various ways for each particular application, but such implementation decisions do not cause a departure from the scope of the present disclosure. In accordance with various embodiments, a processor, device, component, circuit, structure, machine, module, etc. can be configured to perform one or more of the functions described herein. The term “configured to” or “configured for” as used herein with respect to a specified operation or function refers to a processor, device, component, circuit, structure, machine, module, etc. that is physically constructed, programmed and/or arranged to perform the specified operation or function.

Furthermore, a person of ordinary skill in the art would understand that various illustrative logical blocks, modules, devices, components and circuits described herein can be implemented within or performed by an integrated circuit (IC) that can include a general purpose processor, a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) or other programmable logic device, or any combination thereof. The logical blocks, modules, and circuits can further include antennas and/or transceivers to communicate with various components within the network or within the device. A general purpose processor can be a microprocessor, but in the alternative, the processor can be any conventional processor, controller, or state machine. A processor can also be implemented as a combination of computing devices, e.g.， a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other suitable configuration to perform the functions described herein.

If implemented in software, the functions can be stored as one or more instructions or code on a computer-readable medium. Thus, the steps of a method or algorithm disclosed herein can be implemented as software stored on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that can be enabled to transfer a computer program or code from one place to another. A storage media can be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer.

In this document, the term "module" as used herein, refers to software, firmware, hardware, and any combination of these elements for performing the associated functions described herein. Additionally, for purpose of discussion, the various modules are described as discrete modules； however, as would be apparent to one of ordinary skill in the art, two or more modules may be combined to form a single module that performs the associated functions according embodiments of the invention.

Additionally, memory or other storage, as well as communication components, may be employed in embodiments of the invention. It will be appreciated that, for clarity purposes, the above description has described embodiments of the invention with reference to different functional units and processors. However, it will be apparent that any suitable distribution of functionality between different functional units, processing logic elements or domains may be used without detracting from the invention. For example, functionality illustrated to be performed by separate processing logic elements, or controllers, may be performed by the same processing logic element, or controller. Hence, references to specific functional units are only references to a suitable means for providing the described functionality, rather than indicative of a strict logical or physical structure or organization.

Various modifications to the implementations described in this disclosure will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other implementations without departing from the scope of this disclosure. Thus, the disclosure is not intended to be limited to the implementations shown herein, but is to be accorded the widest scope consistent with the novel features and principles disclosed herein, as recited in the claims below.

Claims

A method performed by a first communication node, the method comprising:

receiving a plurality of downlink signals from a second communication node；

identifying a plurality of logical resources, each of the plurality of logical resources associated with a respective one of the plurality of downlink signals；

determining, for each set of M logical resources, N physical random access channel (PRACH) resources, where M and N are positive integers； and

transmitting an uplink signal, wherein the uplink signal uses N PRACH resources to transmit M preambles.
The method of claim 1, wherein each PRACH resource is a time slot and M is equal to N.
The method of claim 1, wherein each PRACH resource is a time slot and M is less than N.
The method of claim 1, wherein each PRACH resource is a time slot and M is greater than N.
The method of claim 1, wherein the plurality of downlink signals comprises at least one of: a reference signal and a synchronization signal.
The method of claim 1, wherein each of the plurality of downlink signals is associated with a physical random access channel (PRACH) configuration index value, and wherein each PRACH configuration index value is associated with at least one physical resource in the time-frequency domain.
The method of claim 1, wherein each of the plurality of downlink signals is associated with a downlink signal index value, and wherein each downlink signal index value is associated with a respective one of a plurality of preamble group index values, each preamble group index value being associated with at least one predetermined preamble format.
The method of claim 1, wherein the plurality of downlink signals comprises a plurality of synchronization blocks, each synchronization block associated with a respective preamble format.
A method performed by a first communication node, the method comprising:

sending a plurality of downlink signals to a second communication node；

receiving an uplink signal from the second communication node；

decoding M preambles from N PRACH resources from the uplink signal, the M preambles identifying M downlink signals of the plurality of downlink signals, wherein M and N are positive integers； and

transmitting a random access response referencing at least one of the M preambles to the second communication node.
The method of claim 9, wherein each PRACH resource is a time slot and M is equal to N.
The method of claim 9, wherein each PRACH resource is a time slot and M is less than N.
The method of claim 9, wherein each PRACH resource is a time slot and M is greater than N.
The method of claim 9, wherein the plurality of downlink signals comprises at least one of:areference signal and a synchronization signal.
The method of claim 9, wherein each of the plurality of downlink signals is associated with a physical random access channel (RACH) configuration index value, and wherein each PRACH configuration index value is associated with at least one physical resource in the time-frequency domain.
The method of claim 9, wherein each of the plurality of downlink signals is associated with a downlink signal index value, and wherein each downlink signal index value is associated with a respective one of a plurality of preamble group index values, each preamble group index value being associated with at least one predetermined preamble format.
The method of claim 9, wherein the plurality of downlink signals comprises a plurality of synchronization blocks, each synchronization block associated with a respective preamble format.
A first communication node, comprising:

a receiver configured to:

receive a plurality of downlink signals from a second communication node, and

identify a plurality of logical resources, each of the plurality of logical resources associated with a respective one of the plurality of downlink signals；

at least one processor configured to:

determine, for each set of M logical resources, N physical random access channel (PRACH) resources, where M and N are positive integers； and

a transmitter configured to:

transmit an uplink signal, wherein the uplink signal uses N PRACH resources to transmit M preambles.
The first communication node of claim 17, wherein each PRACH resource is a time slot and M is equal to N.
The first communication node of claim 17, wherein each PRACH resource is a time slot and M is less than N.
The first communication node of claim 17, wherein each PRACH resource is a time slot and M is greater than N.
The first communication node of claim 17, wherein the plurality of downlink signals comprises at least one of: a reference signal and a synchronization signal.
The first communication node of claim 17, wherein each of the plurality of downlink signals is associated with a physical random access channel (PRACH) configuration index value, and wherein each PRACH configuration index value is associated with at least one physical resource in the time-frequency domain.
The first communication node of claim 17, wherein each of the plurality of downlink signals is associated with a downlink signal index value, and wherein each downlink signal index value is associated with a respective one of a plurality of preamble group index values, each preamble group index value being associated with at least one predetermined preamble format.
The first communication node of claim 17, wherein the plurality of downlink signals comprises a plurality of synchronization blocks, each synchronization block associated with a respective preamble format.
A first communication node, comprising:

a transmitter configured to:

send a plurality of downlink signals to a second communication node；

a receiver configured to:

receive an uplink signal from the second communication node；

at least one processor configured to:

decode M preambles from N PRACH resources from the uplink signal, the M preambles identifying M downlink signals of the plurality of downlink signals, wherein M and N are positive integers, wherein the transmitted is configured to transmit a random access response referencing at least one of the M preambles to the second communication node.
The first communication node of claim 25, wherein each PRACH resource is a time slot and M is equal to N.
The first communication node of claim 25, wherein each PRACH resource is a time slot and M is less than N.
The first communication node of claim 25, wherein each PRACH resource is a time slot and M is greater than N.
The first communication node of claim 25, wherein the plurality of downlink signals comprises at least one of: a reference signal and a synchronization signal.
The first communication node of claim 25, wherein each of the plurality of downlink signals is associated with a physical random access channel (PRACH) index value, and wherein each PRACH configuration index value is associated with at least one physical resource in the time-frequency domain.
The first communication node of claim 25, wherein each of the plurality of downlink signals is associated with a downlink signal index value, and wherein each downlink signal index value is associated with a respective one of a plurality of preamble group index values, each preamble group index value being associated with at least one predetermined preamble format.
The first communication node of claim 25, wherein the plurality of downlink signals comprises a plurality of synchronization blocks, each synchronization block associated with a respective preamble format.