Timing and Frame Structure in an Integrated Access Backhaul (IAB) Network

Abstract

A wireless communication system and method for communicating in an integrated access backhaul (IAB) network are provided. A first wireless communication device of a multi-hop wireless network receives a first transmission timing adjustment command. The first wireless communication device transmits a first communication signal including backhaul data to a second wireless communication device of the multi-hop wireless network based at least on the first transmission timing adjustment command. The first wireless communication device transmits a second communication signal to a third wireless communication device of the multi-hop wireless network based at least on the first transmission timing adjustment command.

Description

[0001] Navid Abedini,Junyi Li,Karl Georg Hampel,Hong Cheng,Jianghong Luo,Juergen Cezanne,Muhammad Nazmul Islam,Sundar Subramanian

[0002] This application is a divisional application of the application filed on April 7, 2020, with application number 201880065434.6 and invention title "Timing and Frame Structure in an Integrated Access Backhaul (IAB) Network".

[0003] Cross - reference to related applications

[0004] This application claims the priority and benefit of U.S. Non - Provisional Patent Application No. 16 / 154,585, filed on October 8, 2018, and U.S. Provisional Patent Application No. 62 / 570,003, filed on October 9, 2017, the entire contents of which are incorporated herein by reference as fully set forth below and for all applicable purposes. Technical field

[0005] Broadly speaking, this application relates to wireless communication systems, and more specifically, to transmitting access data and backhaul data over a wireless link in an integrated access backhaul (IAB) network. Embodiments of the technology can implement and provide solutions and techniques for wireless communication devices (e.g., base stations and user equipment (UE) devices) in an IAB network to maintain synchronization and determine a transmit and / or receive timeline and frame structure for communication. Background art

[0006] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, messaging, broadcasting, etc. These systems can be capable of supporting communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multi - access systems include code - division multiple - access (CDMA) systems, time - division multiple - access (TDMA) systems, frequency - division multiple - access (FDMA) systems, and orthogonal frequency - division multiple - access (OFDMA) systems (e.g., Long - Term Evolution (LTE) systems). A wireless multi - access communication system can include several base stations (BSs) that simultaneously support communication for multiple communication devices, which may otherwise be referred to as user equipment (UEs).

[0007] To meet the growing demand for extended mobile broadband connectivity, wireless communication technologies are evolving from LTE technology to fifth-generation (5G) New Radio (NR) technology. 5G NR can provide access services and backhaul services with gigabit-level throughput. Access services refer to the services between an access node (e.g., a base station) and a UE. Backhaul services refer to the services between an access node and a core network. SUMMARY OF THE INVENTION

[0008] Some aspects of the present disclosure are summarized below to provide a basic understanding of the technologies discussed. This summary is not an extensive overview of all the expected features of the present disclosure, and neither is it intended to identify the key or important elements of all aspects of the present disclosure, nor to delineate the scope of protection of any or all aspects of the present disclosure. Its sole purpose is to present some concepts of one or more aspects of the present disclosure in a summary form as a prelude to a more detailed description that follows.

[0009] Embodiments of the present disclosure provide mechanisms for communicating in an integrated access backhaul (IAB) network employing a multi-hop topology (e.g., a spanning tree) to transmit wireless access services and backhaul services. For example, a BS or a UE can act as a relay node (e.g., a parent node or a child node), and at least one BS that communicates directly with a core network can act as a root node. The relay node can exchange synchronization information with one or more other relay nodes, adjust an internal synchronization reference, and / or determine a transmit and / or receive timeline and / or frame structure (e.g., an interval period and a cyclic prefix (CP)) for transmitting wireless access services and / or backhaul services with the one or more other relay nodes.

[0010] For example, in one aspect of the present disclosure, a method of wireless communication includes: receiving, by a first wireless communication device of a multi-hop wireless network, a first transmission timing adjustment command. The method includes: transmitting, by the first wireless communication device, a first communication signal including backhaul data with a second wireless communication device of the multi-hop wireless network based at least on the first transmission timing adjustment command. The method includes: transmitting, by the first wireless communication device, a second communication signal with a third wireless communication device of the multi-hop wireless network based at least on the first transmission timing adjustment command.

[0011] In additional aspects of the present disclosure, a method of wireless communication includes: receiving, by a first wireless communication device, synchronization information associated with one or more wireless communication devices from the one or more wireless communication devices of a multi-hop wireless network. The method includes: determining, by the first wireless communication device, a transmission timing adjustment for a second wireless communication device among the one or more wireless communication devices based at least on some of the synchronization information. The method includes: sending, by the first wireless communication device, a message for instructing the second wireless communication device to communicate with a third wireless communication device among the one or more wireless communication devices based on the transmission timing adjustment.

[0012] In additional aspects of the present disclosure, a device includes a transceiver configured to receive a first transmission timing adjustment command, wherein the device is associated with a multi-hop wireless network. The transceiver is further configured to transmit a first communication signal including backhaul data to a first wireless communication device of the multi-hop wireless network based at least on the first transmission timing adjustment command. The transceiver is further configured to transmit a second communication signal to a second wireless communication device of the multi-hop wireless network based at least on the first transmission timing adjustment command.

[0013] In additional aspects of the present disclosure, a device includes a transceiver configured to receive synchronization information associated with one or more wireless communication devices from the one or more wireless communication devices of a multi-hop wireless network. The device further includes a processor configured to determine a transmission timing adjustment for a first wireless communication device among the one or more wireless communication devices based at least on some of the synchronization information. The transceiver is further configured to send a message for instructing the first wireless communication device to communicate with a second wireless communication device among the one or more wireless communication devices based on the transmission timing adjustment.

[0014] After reviewing the following description of specific, exemplary embodiments of the invention in conjunction with the drawings, other aspects, features, and embodiments of the invention will become apparent to those of ordinary skill in the art. While the features of the invention may be discussed with respect to certain embodiments and figures below, all embodiments of the invention may include one or more of the advantageous features discussed herein. In other words, while one or more embodiments may be discussed as having certain advantageous features, one or more of these features may also be used in accordance with the various embodiments of the invention discussed herein. In a similar manner, while the exemplary embodiments may be discussed below as device, system, or method embodiments, it should be understood that these exemplary embodiments may be implemented in various devices, systems, and methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1According to an embodiment of the present disclosure, a wireless communication network is shown.

[0016] Figure 2 According to an embodiment of the present disclosure, an integrated access backhaul (IAB) network is shown.

[0017] Figure 3 According to an embodiment of the present disclosure, an IAB network is shown.

[0018] Figure 4 According to an embodiment of the present disclosure, an IAB network topology is shown.

[0019] Figure 5 According to an embodiment of the present disclosure, an IAB network resource sharing method is shown.

[0020] Figure 6 is a block diagram showing an exemplary user equipment (UE) according to an embodiment of the present disclosure.

[0021] Figure 7 is a block diagram showing an exemplary base station (BS) according to an embodiment of the present disclosure.

[0022] Figure 8 is a timing diagram showing a scheduling method for a radio access network according to an embodiment of the present disclosure.

[0023] Figure 9 is a timing diagram showing a scheduling method for an IAB network according to an embodiment of the present disclosure.

[0024] Figure 10 is a timing diagram showing a scheduling method for an IAB network according to an embodiment of the present disclosure.

[0025] Figure 11 is a signaling diagram showing an IAB communication method according to an embodiment of the present disclosure.

[0026] Figure 12 is a signaling diagram showing an IAB communication method according to an embodiment of the present disclosure.

[0027] Figure 13 According to an embodiment of the present disclosure, a distributed synchronization method is shown.

[0028] Figure 14 According to an embodiment of the present disclosure, a centralized synchronization method is shown.

[0029] Figure 15 is a signaling diagram showing a distributed synchronization method according to an embodiment of the present disclosure.

[0030] Figure 16According to an embodiment of the present disclosure, a signaling diagram showing a centralized synchronization method is presented.

[0031] Figure 17 According to an embodiment of the present disclosure, a wireless backhaul network is presented.

[0032] Figure 18 According to an embodiment of the present disclosure, traffic routing overlay in a wireless backhaul network is presented.

[0033] Figure 19 According to an embodiment of the present disclosure, synchronization overlay in a wireless backhaul network is presented.

[0034] Figure 20 According to an embodiment of the present disclosure, synchronization overlay in a wireless backhaul network is presented.

[0035] Figure 21 According to an embodiment of the present disclosure, a signaling diagram showing an IAB communication method is presented.

[0036] Figure 22 A flowchart of a method for communicating in an IAB network according to an embodiment of the present disclosure is presented.

[0037] Figure 23 A flowchart of a method for managing synchronization references in an IAB network according to an embodiment of the present disclosure is presented. Detailed Description

[0038] The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. For the purpose of providing a thorough understanding of the various concepts, the detailed description includes specific details. It will be apparent, however, to one of ordinary skill in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form to avoid obscuring such concepts.

[0039] The techniques described herein can be used in a variety of wireless communication networks. These networks can include Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single-Carrier FDMA (SC-FDMA), and other networks. The terms "network" and "system" are often used interchangeably. CDMA networks can implement radio technologies such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. Cdma2000 covers the IS-2000, IS-95, and IS-856 standards. TDMA networks can implement radio technologies such as Global System for Mobile Communications (GSM). OFDMA networks can implement radio technologies such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). 3GPP Long-Term Evolution (LTE) and Advanced LTE (LTE-A) are new releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). Cdma2000 and UMB are described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). The techniques described herein can be used in the wireless networks and radio technologies mentioned above and other wireless networks and radio technologies, such as next-generation networks including 5G NR. Some 5G NR networks (also known as (e.g., fifth-generation) (5G) operating in the millimeter wave band) can operate in various frequency bands (e.g., millimeter wave or sub-6 MHz) covering both licensed and unlicensed spectra.

[0040] This disclosure describes mechanisms and techniques for communicating in an IAB network. An IAB network can include a combination of a wireless access link between a BS and a UE and a wireless backhaul link between BSs. An IAB network can employ a multi-hop topology (e.g., a spanning tree) for transmitting access traffic and backhaul traffic. One of the BSs can be configured to have a fiber connection to communicate with the core network. In some scenarios, a BS can act as an anchor node (e.g., a root node) to transmit backhaul traffic between the core network and the IAB network. In other scenarios, one BS can play the role of a central node in combination with a connection to the core network. And in some arrangements, BSs and UEs can be referred to as relay nodes in the network.

[0041] The BS can play various roles in the network in a static or dynamic nature. For example, each BS can have one or more parent nodes. These parent nodes can include other BSs. The BS can have one or more child nodes, and the child nodes can include other BSs and / or UEs. The UE can act as a child node. The parent node can act as an access node for the child node. The parent node can be referred to as an access function (ACF) node. The child node can act as a UE for the parent node and can be referred to as a UE function (UEF) node. The BS can act as an ACF node when communicating with the child node and can act as a UEF node when communicating with the parent node. The disclosed embodiments generally provide signaling mechanisms for nodes in an IAB network to maintain synchronization and determine the transmit and / or receive timelines and frame structures for communication. Given the various topological arrangements of an IAB network and the constraints / requirements imposed on network synchronization, it helps the overall network functionality and performance for a positive user experience.

[0042] In one embodiment, the relay node can maintain and track one or more synchronization references for communication in the network. The synchronization reference can be an internal reference or an external reference at the node, such as a Global Positioning System (GPS) connected to the node. The relay node can exchange synchronization information, for example, via messages or reference signals. The central entity can collect synchronization reports from the relay nodes and configure the relay nodes with synchronization adjustments. Thus, the relay node can adjust the internal synchronization reference based on the synchronization information received from other relay nodes, the timing information received from the GPS, the adjustments received from the central entity, and / or the adjustments received from a specific relay node selected by the central entity. Therefore, the present disclosure provides techniques for over-the-air (OTA) synchronization in a multi-hop IAB network.

[0043] In one embodiment, when the relay node acts as an ACF node, the relay node can determine or utilize several parameters. These parameters can include the interval period for communicating with the corresponding UEF node, transmit timing, receive time, and / or cyclic prefix (CP) mode (e.g., normal CP mode or extended CP (ECP) mode). In one embodiment, the central entity can determine the adjustment information for the relay nodes to communicate with each other, and the adjustment information includes the interval period, transmit timing adjustment, receive time adjustment, and / or CP mode, and can provide the adjustment information to the relay nodes.

[0044] Aspects of the techniques discussed herein may provide several benefits. For example, the use of the ACF-UEF relationship among relay nodes can leverage at least some of the LTE techniques in current LTE technology, such as scheduling and timing advance mechanisms. The use of multiple synchronization references and the exchange of synchronization information allow nodes to synchronize with each other and to a reliable synchronization source (e.g., GPS). The flexibility to choose between ECP mode, inter-period insertion, and / or transmit and / or receive timing adjustment can avoid interference and improve resource utilization efficiency. These and other benefits are more fully recognized and discussed below.

[0045] Figure 1 According to an embodiment of the present disclosure, a wireless communication network 100 is shown. Network 100 includes a plurality of BSs 105, a plurality of UEs 115, and a core network 130. Network 100 may be an LTE network, an LTE-A network, a millimeter wave (mmW) network, a new radio (NR) network, a 5G network, or any other successor network to LTE.

[0046] The BS 105 may communicate wirelessly with the UE 115 via one or more BS antennas. Each BS 105 may provide communication coverage for a respective geographic coverage area 110. In 3GPP, the term "cell" may refer to this specific geographic coverage area of the BS and / or the BS subsystem serving the coverage area, depending on the context in which the term is used. In Figure 1 the example shown, BSs 105a, 105b, 105c, 105d, and 105e are examples of macro BSs for coverage areas 110a, 110b, 110c, 110d, and 110e, respectively.

[0047] The communication link 125 shown in network 100 may include an uplink (UL) transmission from UE 115 to BS 105, or a downlink (DL) transmission from BS 105 to UE 115. The communication link 125 is referred to as a radio access link. The UEs 115 may be dispersed throughout the network 100, and each UE 115 may be fixed or mobile. The UE 115 may also be referred to as a mobile station, user station, mobile unit, user unit, radio unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile user station, access terminal, mobile terminal, wireless terminal, remote terminal, cellular phone, user agent, mobile client, client, or some other suitable term. The UE 115 may also be a cellular phone, personal digital assistant (PDA), wireless modem, wireless communication device, handheld device, tablet computer, laptop computer, cordless phone, personal electronic device, handheld device, tablet-type computer, laptop computer, cordless phone, personal electronic device, handheld device, personal computer, wireless local loop (WLL) station, Internet of Things (IoT) device, Internet of Everything (IoE) device, machine type communication (MTC) device, household appliance, automobile, etc.

[0048] The BS 105 may communicate with the core network 130 via the fiber optic link 134 and with each other. The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. At least some of the BSs 105 (e.g., which may be examples of evolved Node Bs (eNBs), next generation Node Bs (gNBs), or access node controllers (ANCs)) may interface with the core network 130 via the backhaul link 134 (e.g., S1, S2, etc.) and may perform radio configuration and scheduling for communication with the UE 115. In various examples, the BSs 105 may communicate with each other directly or indirectly (e.g., via the core network 130) on the backhaul link 134 (e.g., X1, X2, etc.).

[0049] Each BS 105 may also communicate with several UEs 115 via several other BSs 105, where the BS 105 may be an example of a smart radio headend. In an alternative configuration, the various functions of each BS 105 may be distributed across the various BSs 105 (e.g., radio headends and access network controllers) or combined into a single BS 105.

[0050] In some implementations, network 100 utilizes orthogonal frequency division multiplexing (OFDM) on the downlink and single carrier frequency division multiplexing (SC-FDM) on the UL. OFDM and SC-FDM divide the system bandwidth into multiple (K) orthogonal subcarriers, where the subcarriers are also generally referred to as tones, frequency bands, etc. Each subcarrier can be modulated with data. Typically, modulation symbols are transmitted using OFDM in the frequency domain and using SC-FDM in the time domain. The spacing between adjacent subcarriers can be fixed, and the total number (K) of subcarriers can depend on the system bandwidth. The system bandwidth can also be divided into subbands.

[0051] In one embodiment, BS 105 can allocate or schedule transmission resources (e.g., in the form of time-frequency resource blocks) for DL transmissions and UL transmissions in network 100. DL refers to the transmission direction from BS 105 to UE 115, and conversely UL refers to the transmission direction from UE 115 to BS 105. The communication can be in the form of radio frames. The radio frame can be divided into, for example, a plurality of subframes of about 10. Each subframe can be divided into, for example, about 2 time slots. In the frequency division duplex (FDD) mode, UL transmissions and DL transmissions can occur simultaneously in different frequency bands. For example, each subframe includes a UL subframe in the UL frequency band and a DL subframe in the DL frequency band. In the time division duplex (TDD) mode, UL transmissions and DL transmissions occur at different time periods using the same frequency band. For example, a subset of subframes (e.g., DL subframes) in the radio frame can be used for DL transmissions, and another subset of subframes (e.g., UL subframes) in the radio frame can be used for UL transmissions.

[0052] DL subframes and UL subframes can also be further divided into several regions. For example, each DL subframe or UL subframe can have predefined regions for the transmission of reference signals, control information, and data. A reference signal is a predetermined signal that facilitates communication between BS105 and UE 115. For example, the reference signal can have a specific pilot pattern or structure, where the pilot tones can span an operable bandwidth or frequency band that are all located at predefined times and predefined frequencies. For example, BS 105 can transmit cell-specific reference signals (CRS) and / or channel state information-reference signals (CSI-RS) so that UE 115 can estimate the DL channel. Similarly, UE 115 can transmit sounding reference signals (SRS) so that BS 105 can estimate the UL channel. Control information can include resource allocation and protocol control. Data can include protocol data and / or operable data. In some embodiments, BS 105 and UE 115 can use self-contained subframes for communication. A self-contained subframe can include a portion for DL communication and a portion for UL communication. A self-contained subframe can be DL-centric or UL-centric. A DL-centric subframe can include a longer duration for DL communication compared to that for UL communication. A UL-centric subframe can include a longer duration for UL communication compared to that for DL communication.

[0053] In one embodiment, a UE 115 attempting to access network 100 may perform an initial cell search by detecting a primary synchronization signal (PSS) from BS 105. The PSS may achieve synchronization of the periodic timing and may indicate a physical layer identity value. Then, the UE 115 may receive a secondary synchronization signal (SSS). The SSS may achieve radio frame synchronization and may provide a cell identity value, which may be combined with the physical layer identity value to identify the cell. The SSS may also achieve detection of the duplex mode and the cyclic prefix length. Some systems, such as TDD systems, may transmit the SSS instead of the PSS. Both the PSS and the SSS may be respectively located in the central part of the carrier. After receiving the PSS and the SSS, the UE 115 may receive a master information block (MIB), which may be transmitted in a physical broadcast channel (PBCH). The MIB may contain system bandwidth information, a system frame number (SFN), and a physical hybrid ARQ indicator channel (PHICH) configuration. After decoding the MIB, the UE 115 may receive one or more system information blocks (SIBs). For example, SIB1 may contain cell access parameters and scheduling information for other SIBs. Decoding SIB1 may enable the UE 115 to receive SIB2. SIB2 may contain radio resource configuration (RRC) configuration information related to a random access channel (RACH) process, paging, a physical uplink control channel (PUCCH), a physical uplink shared channel (PUSCH), power control, an SRS, and cell barring. After obtaining the MIB and / or the SIB, the UE 115 may perform a random access process to establish a connection with the BS 105. After establishing the connection, the UE 115 and the BS 105 may enter a normal operation phase, in which operable data may be exchanged.

[0054] Figure 2FIG. 200 shows an IAB network 200 according to an embodiment of the present disclosure. Network 200 is substantially similar to network 100. For example, BS 105 communicates with UE 115 over wireless access link 125. However, in network 200, only one BS (e.g., BS 105c) is connected to fiber optic backhaul link 134. Over wireless backhaul link 234, other BSs 105a, 105b, 105d, and 105e communicate wirelessly with each other and with BS 105c. As described in more detail herein, BS 105c connected to fiber optic backhaul link 134 can act as an anchor for other BSs 105a, 105b, 105d, and 105e to communicate with core network 130. Wireless access link 125 and wireless backhaul link 234 can share resources for communication in network 200. Network 200 may also be referred to as a self-backhaul network. Network 200 can improve wireless link capabilities, reduce latency, and reduce deployment costs.

[0055] Figure 3 FIG. 300 shows an IAB network 300 according to an embodiment of the present disclosure. Network 300 is similar to network 200 and shows the use of the millimeter wave (mmWav) band for communication. In network 300, a single BS (e.g., BS 105c) is connected to fiber optic backhaul link 134. Other BSs 105a, 105b, 105d, and 105e use directional beams 334, e.g., to communicate with each other and with BS 105c over wireless link 234. BS 105 may also use narrow directional beam 325, e.g., to communicate with UE 115 over wireless link 125. Directional beam 334 may be substantially similar to directional beam 325. For example, BS 105 may use analog beamforming and / or digital beamforming to form directional beams 334 and 325 for transmission and / or reception. Similarly, UE 115 may use analog beamforming and / or digital beamforming to form directional beam 325 for transmission and / or reception. The use of mmmWav can increase network throughput and reduce latency. The use of narrow directional beams 334 and 325 can minimize inter-link interference. Thus, network 300 can improve system performance.

[0056] Figure 4Shows an IAB network topology 400 according to an embodiment of the present disclosure. The topology 400 may be adopted by network 200 and network 300. For example, BS 105 and UE 115 may be configured to form a logical spanning tree configuration as shown in topology 400 for transmitting access services and / or backhaul services. The topology 400 may include an anchor point 410 coupled to a fiber optic link 134 for communication with a core network (e.g., core network 130). The anchor point 410 may correspond to BS 105c in network 200 and network 300.

[0057] The topology 400 includes a plurality of logical levels 402. In Figure 4 the example, the topology 400 includes three levels 402 shown as 402a, 402b, and 402c. In some other embodiments, the topology 400 may include any suitable number of levels 402 (e.g., two, three, four, five, or six). Each level 402 may include a combination of UE 115 and BS 105 interconnected by logical links 404 shown as 404a, 404b, and 404c. For example, the logical link 404 between BS 105 and UE 115 may correspond to a radio access link 125, and conversely, the logical link 404 between two BS 105s may correspond to a radio backhaul link 234. BS 105 and UE 115 may be referred to as relay nodes in the topology 400.

[0058] The nodes (e.g., BS 105) in level 402a may act as relays for the nodes in level 402b, e.g., to relay backhaul traffic between the nodes and the anchor point 410. Similarly, the nodes (e.g., BS 105) in level 402b may act as relays for the nodes in level 402c. For example, the nodes in level 402a are the parent nodes of the nodes in level 402b, and the nodes in level 402c are the child nodes of the nodes in level 402b. The parent nodes may act as ACF nodes, and the child nodes may act as UEF nodes.

[0059] For example, BS 105 can implement both ACF and UEF, and can act as an ACF node and a UEF node depending on which node the BS is communicating with. For example, BS 105 (shown as pattern-filled) in stage 402b can act as an access node when communicating with BS 105 or UE 115 in stage 402c. Alternatively, when communicating with BS 105 in stage 402a, BS 105 can act as a UE. When the communication is with a node in a higher level or with a smaller number of hops to the anchor point 410, the communication is referred to as UL communication. When the communication is with a node in a lower level or with a larger number of hops to the anchor point 410, the communication is referred to as DL communication. In some embodiments, the anchor point 410 can allocate resources for the link 404. Mechanisms for scheduling UL transmissions and DL transmissions and / or allocating resources based on the topology 400 are described in more detail herein.

[0060] Figure 5 According to an embodiment of the present disclosure, an IAB network resource sharing method 500 is shown. The method 500 shows a resource partitioning for use in the topology 400. In Figure 5 it, the x-axis represents time in some constant unit. The method 500 time-divides the resources in the IAB network (e.g., network 200 and network 300) into resource 510 and resource 520. The resources 510 and 520 can include time-frequency resources. For example, each resource 510 or 520 can include several symbols in time (e.g., OFDM symbols) and several subcarriers in frequency. In some embodiments, each resource 510 or resource 520 shown can correspond to a subframe, a time slot, or a transmission time interval (TTI), which can carry one medium access control (MAC) layer transport block.

[0061] By way of example, the method 500 can allocate the resource 510 to the links 404a and 404c in the topology 400 for transmitting UL traffic and / or DL traffic. The method 500 can allocate the resource 520 to the link 404b in the topology 400 for transmitting UL traffic and / or DL traffic. The time-division of the resources in the alternating manner shown in the method 500 can reduce interference between different stages 402, overcome the half-duplex constraint, and reduce the transmit-receive interval period.

[0062] Figure 6is a block diagram of an exemplary UE 600 in accordance with an embodiment of the present disclosure. The UE 600 may be the UE 115 as discussed above. As shown, the UE 600 may include a processor 602, a memory 604, an IAB communication module 608, a transceiver 610 including a modem subsystem 612 and a radio frequency (RF) unit 614, and one or more antennas 616. These elements may be in direct or indirect communication with each other, for example, via one or more buses.

[0063] The processor 602 may include a central processing unit (CPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a controller, a field programmable gate array (FPGA) device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein. The processor 602 may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0064] The memory 604 may include a cache memory (e.g., a cache memory of the processor 602), random access memory (RAM), magnetoresistive RAM (MRAM), read only memory (ROM), programmable read only memory (PROM), erasable programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), flash memory, solid state memory devices, hard disk drives, other forms of volatile and non-volatile memory, or a combination of different types of memory. In one embodiment, the memory 604 includes non-transitory computer readable media. The memory 604 may store instructions 606. The instructions 606 may include instructions that, when executed by the processor 602, cause the processor 602 to perform the operations described herein in connection with the embodiments of the present disclosure with reference to the UE 115. The instructions 606 may also be referred to as code. The terms "instructions" and "code" should be interpreted broadly to include any type of computer readable statement. For example, the terms "instructions" and "code" may refer to one or more programs, routines, subroutines, functions, procedures, etc. "Instructions" and "code" may include a single computer readable statement or multiple computer readable statements.

[0065] The IAB communication module 608 may be implemented via hardware, software, or a combination thereof. For example, the IAB communication module 608 may be implemented as a processor, circuitry, and / or instructions 606 stored in the memory 604 and executed by the processor 602. The IAB communication module 608 may be used in various aspects of the present disclosure. For example, the IAB communication module 608 is configured to maintain a plurality of synchronization references, provide synchronization information (e.g., including timing and / or frequency) associated with the synchronization references to other nodes (e.g., BS 105), receive synchronization information from other nodes, receive synchronization adjustment commands, receive scheduling information (e.g., interval period, transmission timing, and / or reception timing), adjust the synchronization references based on the received synchronization information and / or the received commands, and / or communicate with other nodes based on the received scheduling information, as described in further detail herein.

[0066] As shown, the transceiver 610 may include a modem subsystem 612 and an RF unit 614. The transceiver 610 may be configured to communicate bidirectionally with other devices such as BS 105. The modem subsystem 612 may be configured to modulate and / or encode data from the memory 604 and / or the IAB communication module 608 according to a modulation and coding scheme (MCS), e.g., a low-density parity-check (LDPC) coding scheme, a turbo coding scheme, a convolutional coding scheme, a digital beamforming scheme, etc. The RF unit 614 may be configured to process (e.g., perform analog-to-digital conversion or digital-to-analog conversion, etc.) the modulated / encoded data from the modem subsystem 612 (for outbound transmissions) or from another source such as the UE 115 or BS 105. The RF unit 614 may be further configured to perform analog beamforming in combination with digital beamforming. Although shown integrated with the transceiver 610, the modem subsystem 612 and the RF unit 614 may be separate devices that are coupled together at the UE 115 to enable the UE 115 to communicate with other devices.

[0067] The RF unit 614 may provide modulated and / or processed data, such as data packets (or more generally, data messages that include one or more data packets and other information), to the antenna 616 for transmission to one or more other devices. For example, this may include the transmission of reservation signals, reservation response signals, and / or any communication signals in accordance with embodiments of the present disclosure. The antenna 616 may further receive data messages sent from other devices. For example, this may include the reception of synchronization information, synchronization adjustment commands, and / or scheduling adjustment information in accordance with embodiments of the present disclosure. The antenna 616 may provide the received data messages for processing and / or demodulation at the transceiver 610. The antenna 616 may include multiple antennas of similar or different designs to maintain multiple transmission links. The RF unit 614 may configure the antenna 616.

[0068] Figure 7 is a block diagram of an exemplary BS 700 in accordance with embodiments of the present disclosure. The BS 700 may be the BS 105 as discussed above. As shown, the BS 700 may include a processor 702, a memory 704, an IAB communication module 708, a transceiver 710 that includes a modem subsystem 712 and an RF unit 714, and one or more antennas 716. These elements may be in direct or indirect communication with each other via one or more buses, for example.

[0069] The processor 702 may have various features as a particular type of processor. For example, these may include a CPU, a DSP, an ASIC, a controller, an FPGA device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein. The processor 702 may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in combination with a DSP core, or any other such configuration.

[0070] The memory 704 may include a cache (e.g., a cache of the processor 702), RAM, MRAM, ROM, PROM, EPROM, EEPROM, flash memory, solid-state memory devices, one or more hard disk drives, a memristor-based array, other forms of volatile and non-volatile memory, or a combination of different types of memory. In some embodiments, the memory 704 may include non-transitory computer-readable media. The memory 704 may store instructions 706. The instructions 706 may include instructions that, when executed by the processor 702, cause the processor 702 to perform the operations described herein. The instructions 706 may also be referred to as code, which may be broadly interpreted to include any type of computer-readable statement, as discussed above with reference to Figure 7 discussed.

[0071] The IAB communication module 708 can be implemented via hardware, software, or a combination thereof. For example, the IAB communication module 708 can be implemented as a processor, circuitry, and / or instructions 706 stored in the memory 604 and executed by the processor 702. The IAB communication module 708 can be used in various aspects of the present disclosure. For example, the IAB communication module 708 is configured to maintain a plurality of synchronization references, provide synchronization information (e.g., including timing and / or frequency) associated with the synchronization references to other nodes (e.g., BS 105, UE 115, and UE 600), receive synchronization information from other nodes, receive synchronization adjustment commands, adjust the synchronization references based on the received synchronization information or the received commands, receive scheduling information (e.g., interval period, transmission timing, and / or reception timing) for communicating with nodes at a higher level (e.g., fewer hops away from the anchor point 410 compared to BS 700), determine scheduling information for communicating with nodes at a lower level (e.g., more hops away from the anchor point 410 compared to BS 700), and / or communicate with nodes based on the received scheduling information and the determined scheduling information, as described in further detail herein.

[0072] As shown, the transceiver 710 can include a modem subsystem 712 and an RF unit 714. The transceiver 710 can be configured to communicate bidirectionally with other devices such as UE 115 and / or another core network element. The modem subsystem 712 can be configured to modulate and / or encode data according to the MCS, e.g., LDPC coding method, turbo coding method, convolutional coding method, digital beamforming method, etc. The RF unit 714 can be configured to process (e.g., perform analog-to-digital conversion or digital-to-analog conversion, etc.) the modulated / encoded data from the modem subsystem 712 (for outbound transmissions) or from another source such as UE 115. The RF unit 714 can be further configured to perform analog beamforming in combination with digital beamforming. Although shown as integrated with the transceiver 710, the modem subsystem 712 and the RF unit 714 can be separate devices that are coupled together at the BS 105 to enable the BS 105 to communicate with other devices.

[0073] The RF unit 714 can provide modulated and / or processed data, e.g., data packets (or more generally, data messages containing one or more data packets and other information), to the antenna 716 for transmission to one or more other devices. For example, this can include, according to embodiments of the present disclosure, the transmission of information to complete attachment to the network and communication with the resident UE 115. The antenna 716 can further receive data messages sent from other devices and provide the received data messages for processing and / or demodulation at the transceiver 710. The antenna 716 can include multiple antennas of similar or different designs to maintain multiple transmission links.

[0074] Figures 8 - 10 Various timelines for communication on a radio access link (e.g., radio access link 125) and a radio backhaul link (e.g., radio backhaul link 234) are shown. In Figures 8 - 10 it, the x-axis represents time in some constant unit. The timelines shown illustrate how various method embodiments can be implemented and are described in detail below.

[0075] Figure 8 is a timing diagram showing a scheduling method 800 for a radio access network according to embodiments of the present disclosure. The method 800 can be employed by a BS (e.g., BS 105) to communicate with a UE (e.g., UE 115) on a radio access link (e.g., radio access link 125). For the sake of brevity of discussion, the method 800 is shown using one UE, but it can be extended to include any suitable number of UEs (e.g., five, ten, twenty, or more than twenty).

[0076] The method 800 generally shows BS / UE communication via the vertical lines shown in the figure. As shown, in the method 800, the BS can, for example, send a DL signal 810 to the UE based on the BS's timing reference (e.g., as shown by the DL transmit (Tx) timeline 802). The UE can receive the DL signal 810 after a propagation delay 830, as shown by the DL receive (Rx) timeline 804. The UE can, for example, send a UL signal 820 to the BS based on the timing reference provided by the BS, as shown by the UL Tx timeline 806.

[0077] To determine the scheduling for a UE, the BS can estimate the round-trip time (RTT) 832 between the BS and the UE, for example, based on a random access procedure. The propagation delay 830 can correspond to half of the RTT 832. The BS can send a timing advance (TA) command to the UE, and the TA command instructs the UE to transmit at a time earlier than the expected scheduled transmission time. The UE is expected to track the DL timing of the BS and adjust the UL timing of the UE based on the DL timing. For example, the BS can schedule the UE to transmit at a specific time according to the timeline 802. The UE can transmit at a time earlier than the scheduled transmission time based on the TA command, such that the transmission can reach the BS at the arrival time according to the timeline 802 of the BS.

[0078] Additionally, the BS can schedule the UE by providing an interval period for the UE to switch between transmission and reception. For example, the BS can schedule the UE to transmit the UL signal 820 at a time after the reception time of the DL signal 810, rather than transmitting the UL signal 820 immediately after receiving the DL signal 810. As shown, there is an interval period 834 between receiving the DL signal 810 and transmitting the UL signal 820. Although the method 800 is described in the context of the BS communicating with the UE over a radio access link, the method 800 can be applied to the BS communicating with another BS over a radio backhaul link, as described in further detail herein.

[0079] Figure 9 is a timing diagram showing a scheduling method 900 for an IAB network according to an embodiment of the present disclosure. Figure 9 The communication between multiple components is shown by vertical lines. The method 900 can be employed by a BS (e.g., BS 105) to communicate with a UE (e.g., UE 115) over a radio access link (e.g., radio access link 125), or to communicate with another BS over a radio backhaul link (e.g., radio backhaul link 234) in an IAB network (e.g., network 200 and network 300). For the sake of brevity of discussion, the method 900 shows three nodes R1, R2, and R3 in three levels (e.g., level 402), but can be extended to include any suitable number of nodes (e.g., five, ten, twenty, or more) configured in any suitable number of levels (e.g., four, five, or more than five).

[0080] Node R1, Node R2, and Node R3 can correspond to a part of topology 400. For example, Node R1 can be at hop h1 (e.g., level 402) with respect to anchor point 410, where h1 is a positive integer. Method 900 can be used in combination with Method 500. For example, Node R1 and Node R2 can correspond to BS 105, and Node R3 can correspond to BS 105 or UE 115. The DL1 Tx timeline 902, DL1 Rx timeline 904, and UL1 Tx timeline 906 between Node R1 and Node R2 are respectively similar to timeline 802, timeline 804, and timeline 806. In some scenarios, Node R1 can act as the parent node or ACF node of Node R2. Node R1 can send DL signal 910 according to the timing reference of Node R1. DL signal 910 can arrive at Node R2 after propagation delay. Node R1 can send a TA command to Node R2. Node R2 can track the DL timing of Node R1, receive the TA command, and send UL signal 920 based on the TA command.

[0081] In some scenarios, Figure 9 nodes can communicate with each other based on scheduling (e.g., timing-based scheduling). For example, Node R2 can communicate with Node R3 (e.g., the child node or UEF node of Node R2). Node R2 can select a DL transmission timing reference (e.g., DL2 Tx) for sending DL signal 930 to Node R3. Figure 9 Three options 932, 934, and 936 for the DL2 Tx timeline 908 are shown.

[0082] In the first option 932, Node R2 can use a single transmission timing reference by aligning the DL transmission timing of Node R2 to the UL transmission timing of Node R2.

[0083] In the second option 934, Node R2 can use two transmission timing references, one for UL transmission based on instructions from Node R1, and the other for DL transmission. Node R2 can align the DL transmission timing of Node R2 to the DL transmission timing of its parent node or ACF node (e.g., Node R1).

[0084] In the third option 936, Node R2 can use two transmission timing references, one for UL transmission based on instructions from Node R1, and the other for DL transmission. Node R2 can align the DL transmission timing of Node R2 to its DL reception timing (e.g., the reception time of DL signal 910).

[0085] Node R2 can select any one of option 932, option 934, and option 936. However, the first option 932 and the third option 936 may result in a large timing misalignment between nodes in the network, depending on the number of hops (e.g., level 402) due to the cumulative effect of propagation delays (e.g., delay 830) from hop to hop. The second option 934 can provide the least amount of timing misalignment because all DL transmission timings in the network can be aligned to the DL transmission timing of the top-level node (e.g., anchor 410).

[0086] After selecting a timing reference for DL transmission, node R2 can schedule UL communication and / or DL communication with node R3. Node R2 can include an interval period in the schedule as required for node R3 to switch between reception and transmission. Node R2 can further measure interference in the network (e.g., cross-link interference), monitor transmissions in the network (e.g., transmission error rate), and schedule UL transmissions based on the measured interference (e.g., to minimize cross-link interference) and the monitored information (e.g., to minimize transmission error rate).

[0087] Figure 10 is a timing diagram showing a scheduling method 1000 for an IAB network according to an embodiment of the present disclosure. Figure 10 Shows communication between multiple components represented by vertical lines. Method 1000 can be adopted by a BS (e.g., BS 105) to communicate with each other over a wireless backhaul link (e.g., wireless backhaul link 234) in an IAB network (e.g., network 200 and network 300). For the sake of brevity of discussion, method 1000 shows node R2 (e.g., in a mesh topology) with two parent nodes R1 and parent node R2, but can be extended to include any suitable number of parent nodes (e.g., three, four, five, or six). Nodes R1, R2, and R3 can correspond to BS 105. Nodes R1, R2, and R3 can correspond to a part of topology 400. For example, node R1 can be at hop h1 with respect to anchor 410, and node R2 can be at hop h2 with respect to anchor 410, where h1 and h2 are positive integers. Method 1000 can be used in combination with method 500.

[0088] In method 1000, node R1 may send DL signal 1010 according to the timing reference of node R1, as shown by DL1 Tx timeline 1001. DL signal 1010 may reach node R3 after the propagation delay, as shown by DL1 Rx timeline 1003. Node R2 may send DL signal 1020 according to the timing reference of node R2, as shown by DL2 Tx timeline 1002. DL signal 1020 may reach node R3 after the propagation delay, as shown by DL2 Rx timeline 1005.

[0089] Node R3 may send UL signal 1030 based on the timing reference directed by node R1 (e.g., via a TA command), as shown by UL1 Tx timeline 1004. Similarly, node R3 may send UL signal 1040 based on the timing reference directed by node R2 (e.g., via a TA command), as shown by UL2 Tx timeline 1006.

[0090] When node R3 adopts the second option 934 described in method 900 with respect to Figure 9 node R3 may align the DL transmission timing of node R3 to the average timing of parent node R1 and parent node R2. When adopting the second option 934, the required maximum interval period may correspond to the maximum RTT in the network, e.g., as shown, the maximum RTT 1050 from parent node R1 and parent node R2 to node R3. After aligning or selecting the timing reference, node R3 may determine the interval period for scheduling communication with the child nodes or UEF nodes of node R3 according to the timing reference, as described in more detail herein.

[0091] As shown in method 800, method 900, and method 1000, the present disclosure provides techniques for timing alignment across multi-hop IAB networks. In one example, the DL transmission timing is aligned across IAB nodes (e.g., BS 105 and relay node 1310) and IAB donors (e.g., anchor 410, BS 105, and relay node 1310), as shown by option 934. In one example, the DL transmission timing and the UL transmission timing are aligned within an IAB node, as shown by option 932.

[0092] Figure 11FIG. 0 is a signaling diagram showing an IAB communication method 1100, according to an embodiment of the present disclosure. The method 1100 is implemented among relay nodes R1, relay node R2, and relay node R3. Node R1 may correspond to a BS (e.g., BS 105 and BS 700, and anchor 410), and may act as an ACF node for node R2 and node R3. Node R2 and node R3 may correspond to a BS and / or a UE (e.g., UE 115 and UE 600), and may act as a UEF node for node R1. The steps of the method 1100 may be performed by a computing device (e.g., a processor, processing circuitry, and / or other suitable components) of the relay node. As shown, the method 1100 includes several enumerated steps, but embodiments of the method 1100 may include additional steps before, after, and between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order. The use of the label "step" is to describe an action or activity, rather than prescribing or requiring an order of events.

[0093] At step 1110, node R1 determines a first interval period (e.g., period 834) for communicating with node R2. For example, node R1 may receive a report from node R2. The report may include capability information of node R2, transmit-receive switching requirements, synchronization reference switching requirements, or scheduling information. The capability information may include the UE category or power classification and / or frequency band of node R2, radio access technology (RAT), measurements and reports supported by node R2, and / or features supported by node R2. The transmit-receive switching requirement refers to the amount of time required for node R2 to switch from a transmit mode to a receive mode or from a receive mode to a transmit mode. The synchronization reference switching requirement refers to the amount of time for node R2 to switch between two or more synchronization references. Node R1 may determine the first interval period based on the report.

[0094] At step 1120, node R1 determines a second interval period (e.g., period 834) for communicating with node R3, based on, for example, the transmit-receive switching of node R3.

[0095] At step 1130, node R1 communicates with node R2 based on the first interval period. For example, node R1 may determine a DL transmission time for transmitting to node R2 and / or a UL transmission time for node R2 based on the first interval period.

[0096] At step 1140, node R1 communicates with node R3 based on the second interval period. For example, node R1 may determine a DL transmission time for transmitting to node R3 and / or a UL transmission time for node R3 based on the second interval period.

[0097] In some embodiments, the first interval period and the second interval period may be indicated in downlink control information (DCI) together with scheduling information. For example, in the context of LTE or NR, node R1 may transmit a physical downlink control channel (PDCCH) signal indicating the scheduling for transmitting signals to node R2. The PDCCH signal may include DCI indicating the interval period. Alternatively, the interval period may be indicated in other DCI, medium access control (MAC) control element (CE), MIB, SIB, and / or RRC messages.

[0098] It can be seen that in method 1100, an ACF node or a parent node (e.g., node R1) may determine a UEF-specific interval period for communicating with a UEF node or a child node (e.g., nodes R2 and R3).

[0099] Figure 12 FIG. is a signaling diagram showing an IAB communication method 1200 according to an embodiment of the present disclosure. Method 1200 is implemented among relay node R1, relay node R2, and relay node R3. Node R1 may correspond to a BS (e.g., BS 105, BS 700, and anchor 410), and may act as an ACF node for nodes R2 and R3. Nodes R2 and R3 may correspond to a BS and / or a UE (e.g., UE 115 and UE 600), and may act as UEF nodes for node R1. The steps of method 1200 may be performed by a computing device (e.g., a processor, processing circuitry, and / or other suitable components) of the relay node. As shown, method 1200 includes several enumerated steps, but embodiments of method 1200 may include additional steps before, after, and between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order.

[0100] Compared with method 1100, method 1200 may improve resource utilization efficiency. For example, in terms of resource utilization, the interval period may be wasted because the interval period is an idle period without transmission. When a parent node (e.g., node R1) determines that all of its child nodes (e.g., nodes R2 and R3) require a certain interval period, the parent node may adjust (e.g., advance or delay) the timing reference of the parent node. In other words, the parent node may adjust the frame boundary or time slot boundary for communicating with the child nodes.

[0101] Alternatively, when the parent node determines multiple intervals in a time slot for communicating with a child node, the parent node may switch from a normal cyclic prefix (CP) mode to an extended CP (ECP) mode. CP refers to prefixing a symbol by repeating the end of the symbol. CP is used in OFDM symbols to mitigate inter-symbol interference (ISI). ECP refers to a CP having a longer duration compared to normal CP.

[0102] At step 1210, node R1 adjusts the timing reference of node R1. For example, node R1 may determine an adjustment such that the adjustment may not cause interference to other relay nodes in the network or create a scheduling conflict with other relay nodes. The adjustment may be a delay and an advance of the timing reference, or include ECP.

[0103] At step 1220, node R1 communicates with node R2 based on the adjusted timing reference.

[0104] At step 1230, node R1 communicates with node R3 based on the adjusted timing reference.

[0105] Accordingly, the present disclosure provides techniques for alignment between IAB nodes and / or IAB donors or within an IAB node based on time slot-level alignment or symbol-level alignment.

[0106] Figures 13 - 16 Various mechanisms are shown for maintaining and / or improving synchronization in an IAB network (e.g., network 200 and network 300) based on, for example, a timing reference of an anchor point (e.g., anchor point 410), relay nodes having a GPS connection (e.g., BS 105 and UE 115), selected relay nodes, and / or a central entity.

[0107] Figure 13 According to an embodiment of the present disclosure, a distributed synchronization method 1300 is shown. Method 1300 may be employed by a BS (e.g., BS 105) and a UE (e.g., UE 115) in an IAB network (e.g., network 100). For the sake of brevity of discussion, method 1300 shows four relay nodes 1310, where one relay node includes a GPS 1320, but this may be extended to include any suitable number of relay nodes (e.g., five, six, ten, or more than ten) and / or GPS connections (e.g., three, four, five, or six).

[0108] In method 1300, node R1 1310 can correspond to a BS, and nodes R2, R3, and R4 1310 can be either BSs or UEs. In one embodiment, node R1 1310 can be an anchor point in the network (e.g., anchor point 410). Each of nodes 1310 can maintain one or more synchronization references and can transmit synchronization information (e.g., timing information and / or frequency information) to each other. Each node 1310 can adjust its synchronization reference based on the synchronization information received from other nodes.

[0109] Nodes 1310 can exchange synchronization information related to internal timing references with each other. Additionally, node R2 1310 can transmit synchronization information based on the timing provided by GPS 1320 to node R1 1310. Nodes 1310 can receive synchronization information from one or more sources (e.g., other nodes 1310 and / or GPS 1320) and can adjust the internal timing reference based on the received synchronization information.

[0110] Figure 14 According to an embodiment of the present disclosure, a centralized synchronization method 1400 is shown. Method 1400 can be employed by a BS (e.g., BS 105) and a UE (e.g., UE 115) in an IAB network (e.g., network 100). Method 1400 is substantially similar to method 1300, but a central entity 1410 is used to determine adjustments to the synchronization references for nodes 1310. The central entity 1410 can be a logical entity and can be physically mapped to any node in the network, such as an anchor node, a relay node 1310, or a dedicated node.

[0111] In method 1400, the central entity 1410 can collect synchronization information from nodes 1310. The central entity 1410 can determine synchronization adjustments for nodes 1310 based on the collected synchronization information. The central entity 1410 can send the determined synchronization adjustments to the corresponding nodes 1310.

[0112] Figure 15 A signaling diagram showing a distributed synchronization method 1500 is according to an embodiment of the present disclosure. Method 1500 is implemented between a relay node R1 (e.g., BS 105, UE 115, and nodes 1310) and other relay nodes (e.g., BS 105, UE 115, and nodes 1310) in an IAB network (e.g., network 100). Node R1 can be coupled to a GPS (e.g., GPS 1320). The other relay nodes can include a combination of a UEF node and an ACF node of node R1. Method 1500 can employ as in regarding Figure 13a similar mechanism as described in method 1300. The steps of method 1500 may be performed by a computing device (e.g., a processor, processing circuitry, and / or other suitable components) of the relay node. As shown, method 1500 includes a number of enumerated steps, but embodiments of method 1500 may include additional steps before, after, and between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order.

[0113] At step 1510, GPS sends timing information to node R1.

[0114] At step 1520, one or more other relay nodes may send messages to node R1. Each message may include synchronization information associated with a synchronization reference (e.g., GPS 1320 or internal synchronization reference) of the corresponding relay node. The synchronization information may include timing information or frequency information. The message may indicate the amount of timing adjustment and / or the amount of frequency adjustment for node R1. In some embodiments, the message is an LTE or NR MAC CE.

[0115] At step 1530, one or more other relay nodes may send a synchronization reference signal, for example, based on a synchronization reference at the corresponding relay node. The synchronization reference signal may be a layer 1 (L1) (e.g., physical layer) signal including a pre-determined signal sequence. In some embodiments, the synchronization reference signal may be carried in an NR synchronization signal (SS) block.

[0116] In one embodiment, the synchronization reference signal and / or the message may be sent based on semi-static scheduling. In one embodiment, the synchronization reference signal and / or the message may be sent in response to a request from node R1.

[0117] At step 1540, node R1 may adjust the synchronization reference of node R1 based on the timing information received from GPS, the synchronization information in the received messages, and / or the measurement (e.g., timing and / or frequency measurement) of the received synchronization reference signal.

[0118] In one embodiment, node R1 may adjust the synchronization reference of node R1 when detecting that the difference between the synchronization reference of node R1 and the received synchronization reference signal exceeds a threshold.

[0119] In some embodiments, there may be a priority level associated with each source of synchronization information. Information about the priority level may be included in each respective synchronization message indicating the source of the synchronization information, e.g., whether the synchronization information is based on GPS or an internal synchronization reference. Additionally or alternatively, information about the priority level may be indicated by other messages, by other nodes in the system, or obtained from a higher layer. In some embodiments, each message may include a priority level indicating the hop count or level (e.g., level 402) at which the respective node is located. Thus, a node receiving synchronization information (e.g., node R1) may adjust the internal synchronization reference of the node based on the priority level. For example, the node may adjust the internal synchronization reference based on an average determined according to the highest priority synchronization information.

[0120] Figure 16 FIG. 16 is a signaling diagram showing a centralized synchronization method 1600, according to an embodiment of the present disclosure. Method 1600 is implemented between a central entity (e.g., central entity 1410) and relay nodes (e.g., BS 105 and UE 115) in an IAB network (e.g., network 100). Method 1600 may employ a similar mechanism as described in method 1400 with respect to Figure 14 The steps of method 1600 may be performed by a computing device (e.g., a processor, processing circuitry, and / or other suitable components) of the relay node. As shown, method 1600 includes a plurality of enumerated steps, but embodiments of method 1600 may include additional steps before, after, and between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order.

[0121] At step 1610, the relay node may send synchronization information to the central entity. The synchronization information may correspond to timing and / or frequency information of the synchronization reference (e.g., GPS 1320 or internal synchronization reference) of the respective relay node.

[0122] At step 1620, the central entity may determine an adjustment to the synchronization reference for the relay node based on the received synchronization information.

[0123] At step 1630, the central entity may send the determined synchronization adjustment to the corresponding relay node. For example, the central entity may direct the first relay node to communicate with the second relay node using a specific adjustment. In some embodiments, the adjustment may include an interval period, a transmission timing adjustment, a reception timing adjustment, a synchronization timing adjustment, and / or a synchronization frequency adjustment. In some embodiments, the central entity may further receive reports from the relay nodes. The reports may include capability information, scheduling information, transmit-receive handover requirements, and synchronization reference handover requirements associated with the relay nodes. The central entity may determine the interval period and / or cyclic prefix configuration (e.g., normal CP or ECP) based on the reports. In some embodiments, the synchronization information and adjustment may be carried in an NR or LTE RRC message.

[0124] Figure 17 According to an embodiment of the present disclosure, a wireless backhaul network 1700 is shown. Network 1700 may be similar to network 200 and network 300. Network 1700 includes a plurality of relay nodes 1310 shown as R1 to R11. Some of the nodes 1310 (e.g., R5 and R8) may include connections to GPS 1320. Network 1700 may adopt topology 400 to establish multi-hop relay links 1702. Node R1 1310 may be an anchor node (e.g., anchor point 410) that communicates with the core network (e.g., network 130) via an optical fiber link (e.g., optical fiber link 134). Node R1 1310 may act as an intermediate node that relays backhaul traffic between the core network and other nodes 1310.

[0125] Figure 18 According to an embodiment of the present disclosure, a traffic routing overlay 1800 on the wireless backhaul network 1700 is shown. Traffic routing overlay 1800 includes a traffic route 1802 established among the nodes 1310 for routing traffic in network 1700. Traffic route 1802 may or may not be overlaid on all the links 1702. For example, although node R7 1310 and node R8 1310 may be connected by link 1702, traffic routing overlay 1800 does not include a traffic route 1802 between node R7 1310 and node R8 1310. Traffic routing overlay 1800 may partition and allocate resources for traffic route 1802 (e.g., overlaid on link 1702) to transmit traffic among the nodes 1310, for example, using method 500. Traffic routing overlay 1800 may include various network control and / or management operations, such as keep-alive and link maintenance operations.

[0126] Figure 19According to an embodiment of the present disclosure, a synchronization overlay 1900 on a wireless backhaul network 1700 is shown. The synchronization overlay 1900 is based on a traffic routing overlay 1800. The synchronization overlay 1900 reuses the traffic routes 1802 established by the traffic routing overlay 1800 and the resources allocated by the traffic routing overlay 1800 to transmit synchronization information and / or adjustment instructions among nodes 1310. The synchronization overlay 1900 may support on-demand exchange of synchronization information and / or adjustments. The synchronization overlay 1900 may also utilize network controls (e.g., keep-alive and link maintenance protocols) supported by the traffic routing overlay 1800.

[0127] Figure 20 According to an embodiment of the present disclosure, a synchronization overlay 2000 on a wireless backhaul network 1700 is shown. The overlay 2000 may establish a route 2002 on a link 1702, rather than reusing the traffic routing overlay 1800 as in the overlay 1900. The route 2002 may be different from the traffic route 1802. For example, the overlay 2000 may establish the route 2002 based on a synchronization source (e.g., GPS 1320) available in the network 1700. Thus, the overlay 2000 may provide better utilization of the synchronization source, but may require resource allocation, determination of scheduling, and / or other network controls separate from the overlay 1800.

[0128] When a network (e.g., network 200 and network 300) employs the overlay 1900 (e.g., reusing the traffic overlay 1800), a UEF node in the network may provide synchronization feedback to a corresponding ACF node, for example, via a MAC CE. An ACF node in the network may receive the feedback from the corresponding UEF node and adjust the synchronization reference based on the feedback.

[0129] When a network employs the overlay 1900 or the overlay 2000, a relay node in the network may transmit a physical reference signal (e.g., in a synchronization signal block (SSB)). Other relay nodes in the network may receive the physical reference signal and may adjust a corresponding synchronization reference based on measurements of the received physical reference signal, e.g., for frequency tracking.

[0130] Figure 21FIG. 0 is a signaling diagram illustrating a synchronization method 2100, according to an embodiment of the present disclosure. The method 2100 is implemented between a relay node R1 (e.g., nodes 1310 and BS 105 and BS 700) in an IAB network (e.g., network 100) and other relay nodes (e.g., nodes 1310, BS 105, and BS 700, and UEs 115 and 600). The other relay nodes may be UEF nodes or child nodes of node R1. Node R1 and the other relay nodes may be part of overlay 1900 or overlay 2000. The steps of the method 2100 may be performed by a computing device (e.g., a processor, processing circuitry, and / or other suitable components) of the relay node. As shown, the method 2100 includes a number of enumerated steps, but embodiments of the method 2100 may include additional steps before, after, and between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order.

[0131] At step 2110, node R1 determines a first synchronization reference adjustment for one or more internal synchronization references of node R1. The first adjustment may be relatively small, e.g., a few samples or less than a symbol time period. Node R1 may adjust the internal synchronization reference and continue communicating with the other relay nodes.

[0132] At step 2120, node R1 communicates with the other relay nodes based on the adjusted synchronization reference.

[0133] At step 2130, the other relay nodes may track the adjustment based on the communication with node R1. For example, a relay node may receive a communication or synchronization signal from node R1 and may detect the adjustment from the received communication signal. Thus, the relay node may adjust the internal synchronization reference of the node based on the detected adjustment.

[0134] At step 2140, after a period of time, node R1 determines a second synchronization reference adjustment for the internal synchronization reference. The second adjustment may be relatively large, e.g., greater than a symbol time period. Node R1 may determine that resynchronization from the other relay nodes is needed.

[0135] At step 2150, node R1 sends a resynchronization request to the other relay nodes. Node R1 may send the resynchronization request in a broadcast mode. Node R1 may additionally indicate resources and / or configuration information (e.g., a set of synchronization reference signals or synchronization pulses) that the other relay nodes may use for resynchronization. In some embodiments, node R1 may further indicate a resynchronization configuration, e.g., including the amount of adjustment and / or when the adjustment becomes effective (e.g., an offset time period or number of time slots with respect to the transmission time of the request).

[0136] At step 2160, upon receiving a resynchronization request, other relay nodes may perform resynchronization based on the request. For example, a relay node may receive a synchronization reference signal based on the resources and / or configuration indicated in the request, and may adjust the corresponding internal synchronization reference at a start time corresponding to an offset time period or number of time slots indicated in the request. Although method 2100 is described in the context of time synchronization and adjustment, method 2100 may be applied to perform frequency synchronization and adjustment.

[0137] Figure 22 is a flowchart of a method 2200 for communicating in an IAB network according to an embodiment of the present disclosure. The network may be similar to network 200, network 300, and network 1700, and may be configured with topology 400 and / or overlays 1800, 1900, and 2000. The steps of method 2200 may be performed by a computing device (e.g., a processor, processing circuitry, and / or other suitable components) of a wireless communication device such as BS 105 and BS 700, and UE115 and UE 600. Method 2200 may employ similar mechanisms as in methods 500, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, and 2100 described respectively in Figure 5 , Figure 8 , Figure 9 , Figure 10 , Figure 11 , Figure 12 , Figure 13 , Figure 14 , Figure 15 , Figure 16 and Figure 21 As shown, method 2200 includes a number of enumerated steps, but embodiments of method 2200 may include additional steps before, after, and between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order.

[0138] At step 2210, method 2200 includes a first wireless communication device receiving synchronization information from one or more wireless relay devices. The first wireless communication device and the one or more wireless relay devices may correspond to relay node 1310.

[0139] At step 2220, method 2200 includes a first wireless communication device adjusting one or more synchronization references based on at least some of the synchronization information.

[0140] At step 2230, method 2200 includes transmitting communication signals between the first wireless communication device and one or more wireless relay devices based on the one or more adjusted synchronization references. The communication signals may include a combination of backhaul traffic and access traffic.

[0141] In one embodiment, the first wireless communication device may be a BS, and the one or more wireless relay devices may include a parent node (e.g., an ACF node) and / or a child node (e.g., a UEF node) of the first wireless communication device. For example, the one or more wireless relay devices may include a combination of UEs (e.g., child nodes) and other BSs (e.g., child nodes and / or parent nodes). The UEs may be served by the BS over a wireless access link (e.g., wireless access link 125). The BS may relay backhaul traffic for other BSs over a wireless backhaul link (e.g., wireless backhaul link 234).

[0142] In one embodiment, the first wireless communication device may receive synchronization information by receiving a message from a first wireless relay device among the one or more wireless relay devices, the message including at least one of the following: timing information associated with the synchronization reference of the first wireless relay device, frequency information associated with the synchronization reference of the first wireless relay device, capability information of the first wireless relay device, scheduling information of the first wireless relay device, transmit-receive switching requirements of the first wireless relay device, or synchronization reference switching requirements of the first wireless relay device.

[0143] In one embodiment, the first wireless communication device may receive synchronization information by receiving a synchronization reference signal from a first wireless relay device among the one or more wireless relay devices, the synchronization reference signal being based on the synchronization reference of the first wireless relay device. The first wireless communication device may determine a frequency offset and / or a timing offset based on measurements of the received synchronization reference signal.

[0144] In one embodiment, the synchronization information may include priority level information. The priority level information may include the source of the synchronization information, e.g., whether the synchronization information is obtained from GPS or from an internal synchronization reference of the corresponding relay node. The priority level information may also include a hop count (e.g., level 402) indicating the number of hops regarding the original source of the corresponding synchronization reference. Thus, the first wireless communication device may adjust the one or more synchronization references according to the priority level.

[0145] In one embodiment, the first wireless communication device may receive synchronization information from a central entity (e.g., central entity 1410). In one embodiment, the first wireless communication device may further receive at least one of timing information or frequency information from an external synchronization source, and may further adjust one or more synchronization references based on at least one of the timing information or frequency information. The external synchronization source may be a GPS (e.g., GPS 1320) or a synchronization source provided by another radio access technology (RAT). In some embodiments, the first wireless communication device may request synchronization information. In some other embodiments, the first wireless communication device may receive synchronization information based on semi-static scheduling. In one embodiment, the first communication device may send synchronization information associated with one or more synchronization references based on at least one of scheduling, a synchronization information request, measurement of one or more synchronization references, or adjustment of one or more synchronization references.

[0146] In one embodiment, the first wireless communication device may relay the backhaul traffic of one or more wireless relay devices to an anchored wireless communication device (e.g., anchor point 410) communicating with a core network (e.g., core network 130) via an optical fiber link (e.g., optical fiber link 134). The first wireless communication device may communicate with one or more wireless relay devices based on the DL transmission timing of the anchored wireless communication device, for example, using the second option 934 shown in method 900.

[0147] In one embodiment, the first wireless communication device may communicate with the one or more wireless relay devices using a UEF-specific interval period (e.g., interval period 834) based on the capabilities of each wireless relay device (e.g., transmit-receive switching time). For example, the first wireless communication device may determine a first interval period based on the capability parameters of a first wireless relay device among the one or more wireless relay devices. The first wireless communication device may determine a second interval period based on the capability parameters of a second wireless relay device among the one or more wireless relay devices, and the second interval period is different from the first interval period. The first wireless communication device may communicate with the first wireless relay device and the second wireless relay device based on the first interval period and the second interval period, respectively.

[0148] In one embodiment, the first wireless communication device may determine the interval period based on measurements and indications received from the parent node (e.g., ACF node) and / or child node (e.g., UEF node) of the first wireless communication device. In one embodiment, the first wireless communication device may determine the interval period based on the scheduling of the first wireless communication device or the scheduling of other relay nodes. In one embodiment, the first wireless communication device may determine the interval period based on a command received from a central entity.

[0149] In some embodiments, the gap period may be located at any position within a time slot, e.g., at the start of the time slot, at the end of the time slot, or in the middle of the time slot. The gap period may be network-wide, cell-specific, and / or UE-specific. In some embodiments, the gap period may change from time slot to time slot. In some embodiments, the gap period may be configured semi-statically using a semi-persistent mode.

[0150] In one embodiment, a first wireless communication device may communicate simultaneously with a first wireless relay device and a second wireless relay device among one or more wireless relay devices. The first wireless communication may communicate with the first wireless relay device using a first synchronization reference, and may communicate with the second wireless relay device using a second synchronization reference different from the first synchronization reference.

[0151] In one embodiment, the first wireless communication device may switch from normal CP to ECP during communication based on the capability parameters of one or more wireless relay devices. When the first wireless communication device multiplexes communications with multiple relay devices, it may be necessary to extend the duration of the CP (e.g., to ECP) to accommodate the different timings of the multiple relay devices in order to avoid ISI.

[0152] In one embodiment, when communicating simultaneously with multiple wireless relay devices, the first wireless communication device may use different antenna sub-arrays and different digital chains. In this embodiment, it may not be required for the first wireless communication device to switch to the ECP mode. In another embodiment, the first wireless communication device may use different antenna sub-arrays with a single digital chain or a single antenna sub-array with multi-finger beamforming. In this embodiment, it may be required for the first wireless communication device to switch to the ECP mode, and for example, use frequency division multiplexing (FDM) to multiplex the communications.

[0153] In one embodiment, a first wireless communication device may transmit a first communication signal in a communication signal to a first wireless relay device among one or more wireless relay devices based on a first synchronization reference among one or more synchronization references during a first time period. The first wireless communication device may transmit a second communication signal in a communication signal to a second wireless relay device among one or more wireless relay devices based on a second synchronization reference different from the first synchronization reference among one or more synchronization references during a second time period following the first time period. For example, the first wireless communication device may transmit and / or receive a reference signal (e.g., CSI-RS), a control signal, and / or a data signal by scanning transmission and / or reception beams in different directions in consecutive time periods. In some embodiments, a common resource may be allocated to multiple relay devices for transmitting a synchronization signal or a beam reference signal. Since different relay devices may have different propagation delays, the use of ECP may be beneficial for accommodating different delays.

[0154] Although scheduling may accommodate timing misalignment among different nodes and / or avoid ISI by introducing guard periods or using the ECP mode, there is a trade-off between the use of ECP and guard periods. The use of ECP increases the overhead in all symbols within a time slot. However, when the scheduling requires multiple guard periods within a time slot, the use of ECP may be suitable. Conversely, when the scheduling does not require multiple switches between different synchronization references, the use of guard periods may be suitable. For example, a relay node may scan multiple directions towards one node based on a first synchronization reference and then scan multiple directions towards another node based on a second synchronization reference. In such a scenario, the relay node may require a single guard period between the two scans, which may be more efficient compared to using ECP for all symbols.

[0155] In one embodiment, the first wireless communication device may determine whether to select normal CP or ECP based on measurements and indications received from a parent node (e.g., an ACF node) and / or a child node (e.g., a UEF node) of the first wireless communication device, the scheduling of the first wireless communication device, the scheduling of other relay nodes, and / or a command received from a central entity.

[0156] Figure 23is a flowchart of a method 2300 for managing synchronization references in an IAB network according to an embodiment of the present disclosure. The network can be similar to network 200, network 300, and network 1700, and can be configured with topology 400 and / or overlays 1800, 1900, and 2000. The steps of method 2300 can be performed by a computing device (e.g., a processor, processing circuitry, and / or other suitable components) of a wireless communication device such as BS 105 and BS 700, and central entity 1410. Method 2300 can employ similar mechanisms as in methods 500, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, and 2100 described respectively with respect to Figure 5 , Figure 8 , Figure 9 , Figure 10 , Figure 11 , Figure 12 , Figure 13 , Figure 14 , Figure 15 , Figure 16 and Figure 21 respectively. As shown, method 2300 includes a number of enumerated steps, but embodiments of method 2300 can include additional steps before, after, and between the enumerated steps. In some embodiments, one or more of the enumerated steps can be omitted or performed in a different order.

[0157] At step 2310, method 2300 includes receiving, by a central entity, synchronization information associated with one or more wireless relay devices (e.g., BS 105 and BS 700, UE 115 and UE 600, and relay node 1310) from the one or more wireless relay devices. The synchronization information can include frequency information and / or timing information associated with the synchronization reference of the one or more wireless relay devices.

[0158] At step 2320, method 2300 includes determining, by the central entity, a synchronization reference adjustment based on at least some of the synchronization information. The adjustment can include an interval period, cyclic prefix configuration, timing synchronization adjustment, frequency synchronization adjustment, transmission timing adjustment, and / or reception timing adjustment.

[0159] At step 2330, method 2300 includes sending, by the central entity, a message for instructing a first wireless relay device among the one or more wireless relay devices to communicate with a second wireless relay device among the one or more wireless relay devices based on the synchronization reference adjustment.

[0160] In one embodiment, the central entity may collect reports from one or more wireless relay devices. The reports may include at least one of the following: capability information of one or more wireless relay devices, scheduling information of one or more wireless relay devices, transmit-receive handover requirements of one or more wireless relay devices, synchronization reference handover requirements of one or more wireless relay devices, or a priority level associated with a synchronization reference source of one or more wireless relay devices. The central entity may determine at least one of an interval period or a cyclic prefix configuration for a first wireless relay device to communicate with a second wireless relay device based on the reports.

[0161] In one embodiment, both the first wireless communication device and the second wireless communication device may be BSs, where the adjustment is for backhaul communication. For example, the first wireless communication device may be a parent node or an ACF node of the second wireless communication device. Alternatively, the first wireless communication device may be a child node or a UEF node of the second wireless communication device.

[0162] In one embodiment, the first wireless communication device may be a BS, and the second wireless communication device may be a UE, where the adjustment is for access communication.

[0163] In another embodiment, the first wireless communication device may be a UE, and the second wireless communication device may be a BS, where the adjustment is for access communication.

[0164] Information and signals may be represented using any of a variety of different technologies and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips referred to throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or optical particles, or any combination thereof.

[0165] The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed using a general-purpose processor, a DSP, an ASIC, an FPGA, or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

[0166] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over a computer-readable medium as one or more instructions or code. Other examples and implementations also fall within the scope of the present disclosure and the appended claims. For example, due to the nature of software, the functions described above may be implemented using software executed by a processor, hardware, firmware, hardwiring, or any combination of these. The features implementing the functions may also be physically located in multiple locations, including being distributed, such that portions of the functions are implemented at different physical locations. Additionally, as used herein, including in the claims, the "or" as used in a list of items (e.g., a list of items prefaced by a phrase such as "at least one of" or "one or more of") indicates an inclusive list, such that, for example, the list [at least one of A, B, or C] means: A or B or C or AB or AC or BC or ABC (i.e., A and B and C).

[0167] Embodiments of the present disclosure further include a computer-readable medium having program code recorded thereon, the program code including: code for causing a first wireless communication device to receive synchronization information associated with one or more wireless relay devices; code for causing the first wireless communication device to adjust one or more synchronization references based on at least some of the synchronization information; and code for causing the first wireless communication device to transmit communication signals with the one or more wireless relay devices based on the one or more adjusted synchronization references, wherein at least one of the communication signals includes backhaul traffic.

[0168] The computer-readable medium further includes: wherein the code for causing the first wireless communication device to receive synchronization information is further configured to receive, from a first wireless relay device among one or more wireless relay devices, a message including at least one of the following: timing information associated with a synchronization reference of the first wireless relay device, frequency information associated with the synchronization reference of the first wireless relay device, capability information of the first wireless relay device, scheduling information of the first wireless relay device, transmit-receive handover requirements of the first wireless relay device, or synchronization reference handover requirements of the first wireless relay device. The computer-readable medium further includes: wherein the code for causing the first wireless communication device to receive synchronization information is further configured to receive a synchronization reference signal from a first wireless relay device among one or more wireless relay devices, based on the synchronization reference of the first wireless relay device. The computer-readable medium further includes: wherein the code for causing the first wireless communication device to receive synchronization information is further configured to receive a priority level associated with a source of the synchronization information, and wherein the adjustment includes adjusting one or more synchronization references based on the priority level. The computer-readable medium further includes: wherein the code for causing the first wireless communication device to receive synchronization information is further configured to receive a priority level associated with a hop count of one or more wireless relay devices with respect to an original source of a corresponding synchronization reference, and wherein the adjustment includes adjusting one or more synchronization references based on the priority level. The computer-readable medium further includes: wherein the code for causing the first wireless communication device to receive synchronization information is further configured to receive synchronization information from a central entity. The computer-readable medium further includes: code for causing the first wireless communication device to receive at least one of timing information or frequency information from an external synchronization source; and code for causing the first wireless communication device to further adjust one or more synchronization references based on at least one of the timing information or the frequency information. The computer-readable medium further includes: wherein the external synchronization source includes at least one of a Global Positioning System (GPS) or a synchronization source of another radio access technology (RAT). The computer-readable medium further includes: code for causing the first wireless communication device to send a message requesting synchronization information. The computer-readable medium further includes: code for causing the first wireless communication device to send synchronization information associated with one or more synchronization references based on at least one of the following: scheduling, a synchronization information request, measurements of one or more synchronization references, or adjustments to one or more synchronization references. The computer-readable medium further includes: code for causing the first wireless communication device to relay a first communication signal in a communication signal via an optical fiber link to an anchored wireless communication device communicating with a core network, wherein the code for causing the first wireless communication device to transmit the communication signal is further configured to send a second communication signal to a first wireless relay device among one or more wireless relay devices based on a downlink transmission timing of the anchored wireless communication device.The computer-readable medium further includes: wherein the code for causing the first wireless communication device to transmit a communication signal is further configured to transmit a second communication signal in a communication signal including an access service with a first wireless relay device among one or more wireless relay devices. The computer-readable medium further includes: code for causing the first wireless communication device to send a message requesting one or more wireless relay devices to re-synchronize to one or more adjusted synchronization references. The computer-readable medium further includes: code for causing the first wireless communication device to send a configuration for re-synchronizing to one or more adjusted synchronization references. The computer-readable medium further includes: code for causing the first wireless communication device to determine a first interval period based on at least one of the following: a capability parameter of a first wireless relay device among one or more wireless relay devices, scheduling information of the first wireless relay device, a transmit-receive handover requirement of the first wireless relay device, or a synchronization reference handover requirement of the first wireless relay device; and code for causing the first wireless communication device to determine a second interval period based on at least one of the following: a capability parameter of a second wireless relay device among one or more wireless relay devices, scheduling information of the second wireless relay device, a transmit-receive handover requirement of the second wireless relay device, or a synchronization reference handover requirement of the second wireless relay device, the second interval period being different from the first interval period. The computer-readable medium further includes: wherein the code for causing the first wireless communication device to transmit a communication signal is further configured to send a message indicating the first interval period to the first wireless relay device; send a message indicating the second interval period to the second wireless relay device; communicate with the first wireless relay device based on the first interval period; communicate with the second wireless relay device based on the second interval period. The computer-readable medium further includes: wherein the code for causing the first wireless communication device to transmit a communication signal switches from a normal cyclic prefix to an extended cyclic prefix based on at least one of the following: a capability parameter of one or more wireless relay devices, a transmit-receive handover requirement of one or more wireless relay devices, a synchronization reference handover requirement of one or more wireless relay devices, or a synchronization reference of one or more wireless relay devices. The computer-readable medium further includes: wherein the code for causing the first wireless communication device to transmit a communication signal is further configured to: transmit a first communication signal with a first wireless relay device among one or more wireless relay devices based on a first synchronization reference of one or more synchronization references; transmit a second communication signal with a second wireless relay device among one or more wireless relay devices based on a second synchronization reference different from the first synchronization reference among one or more synchronization references. The computer-readable medium further includes: wherein the code for causing the first wireless communication device to transmit a communication signal is further configured to: transmit the first communication signal simultaneously with the second communication signal.The computer-readable medium further includes: wherein the code for causing the first wireless communication device to transmit a communication signal is further configured to: during a first time period, transmit a first communication signal in the communication signals with a first wireless relay device among one or more wireless relay devices based on a first synchronization reference of one or more synchronization references; and during a second time period following the first time period, transmit a second communication signal in the communication signals with a second wireless relay device among one or more wireless relay devices based on a second synchronization reference of one or more synchronization references that is different from the first synchronization reference.

[0169] Embodiments of the present disclosure further include a computer-readable medium having program code recorded thereon, the program code including: code for causing a central unit to receive synchronization information associated with one or more wireless relay devices from one or more wireless relay devices; code for causing the central unit to determine a synchronization reference adjustment based on at least some of the synchronization information in the synchronization information; code for causing the central unit to send a message to direct a first wireless relay device among one or more wireless relay devices to communicate with a second wireless relay device among one or more wireless relay devices based on the synchronization reference adjustment.

[0170] The computer-readable medium further includes: wherein the code for causing the central unit to receive synchronization information is further configured to receive at least one of frequency information associated with the synchronization reference of one or more wireless relay devices or timing information associated with the synchronization reference of one or more wireless relay devices. The computer-readable medium further includes: wherein the code for causing the central unit to send a message is further configured to send a synchronization reference adjustment including at least one of an interval period, a cyclic prefix configuration, a timing synchronization adjustment, a frequency synchronization adjustment, a transmission timing adjustment, or a reception timing adjustment. The computer-readable medium further includes: code for causing the central unit to receive a report from one or more wireless relay devices including at least one of the following: capability information of one or more wireless relay devices, scheduling information of one or more wireless relay devices, transmit-receive switching requirements of one or more wireless relay devices, synchronization reference switching requirements of one or more wireless relay devices, or a priority level associated with the synchronization reference source of one or more wireless relay devices; and code for causing the central unit to determine at least one of an interval period or a cyclic prefix configuration for the first wireless relay device to communicate with the second wireless relay device based on the report.

[0171] Embodiments of the present disclosure also include an apparatus, the apparatus including: a unit for receiving synchronization information associated with one or more wireless relay devices (e.g., transceivers 610 and 710 and antennas 616 and 716); a unit for adjusting one or more synchronization references based on at least some of the synchronization information (e.g., processors 602 and 702); and a unit for transmitting communication signals with one or more wireless relay devices based on the one or more adjusted synchronization references (e.g., transceivers 610 and 710 and antennas 616 and 716), wherein at least one of the communication signals includes backhaul traffic.

[0172] The apparatus further includes: wherein, the unit for receiving synchronization information is further configured to receive a message from a first wireless relay device among one or more wireless relay devices, the message including at least one of the following: timing information associated with a synchronization reference of the first wireless relay device, frequency information associated with the synchronization reference of the first wireless relay device, capability information of the first wireless relay device, scheduling information of the first wireless relay device, transmit-receive handover requirements of the first wireless relay device, or synchronization reference handover requirements of the first wireless relay device. The apparatus further includes: wherein, the unit for receiving synchronization information is further configured to receive a synchronization reference signal from the first wireless relay device among one or more wireless relay devices, based on the synchronization reference of the first wireless relay device. The apparatus further includes: wherein, the unit for receiving synchronization information is further configured to receive a priority level associated with the source of the synchronization information, and wherein the adjustment includes adjusting one or more synchronization references based on the priority level. The apparatus further includes: wherein, the unit for receiving synchronization information is further configured to receive a priority level associated with the number of hops of one or more wireless relay devices with respect to the original source of the respective synchronization reference, and wherein the adjustment includes adjusting one or more synchronization references based on the priority level. The apparatus further includes: wherein, the unit for receiving synchronization information is further configured to receive synchronization information from a central entity. The apparatus further includes: a unit for receiving at least one of timing information or frequency information from an external synchronization source (e.g., transceivers 610 and 710 and antennas 616 and 716), and wherein the unit for adjusting one or more synchronization references further adjusts one or more synchronization references based on at least one of the timing information or frequency information. The apparatus further includes: wherein, the external synchronization source includes at least one of a Global Positioning System (GPS) or a synchronization source of another Radio Access Technology (RAT). The apparatus further includes: a unit for sending a message requesting synchronization information (e.g., transceivers 610 and 710 and antennas 616 and 716). The apparatus further includes: a unit for sending synchronization information associated with one or more synchronization references based on at least one of scheduling, a synchronization information request, measurement of one or more synchronization references, or adjustment of one or more synchronization references (e.g., transceivers 610 and 710 and antennas 616 and 716). The apparatus further includes: a unit for relaying a first communication signal in a communication signal to an anchored wireless communication device communicating with a core network via an optical fiber link (e.g., transceivers 610 and 710 and antennas 616 and 716), wherein the unit for transmitting the communication signal is further configured to send a second communication signal to the first wireless relay device among one or more wireless relay devices based on the downlink transmission timing of the anchored wireless communication device.The apparatus further includes: wherein, the unit for transmitting communication signals is further configured to transmit a second communication signal in the communication signals including access services to a first wireless relay device among one or more wireless relay devices. The apparatus further includes: a unit for sending a message requesting one or more wireless relay devices to re-synchronize to one or more adjusted synchronization references (e.g., transceivers 610 and 710 and antennas 616 and 716). The apparatus further includes: a unit for sending a configuration for re-synchronizing to one or more adjusted synchronization references (e.g., transceivers 610 and 710 and antennas 616 and 716). The apparatus further includes: a unit for determining a first interval period based on at least one of the following: the capability parameters of a first wireless relay device among one or more wireless relay devices, the scheduling information of the first wireless relay device, the transmit-receive switching requirements of the first wireless relay device, or the synchronization reference switching requirements of the first wireless relay device; and a unit for determining a second interval period based on at least one of the following: the capability parameters of a second wireless relay device among one or more wireless relay devices, the scheduling information of the second wireless relay device, the transmit-receive switching requirements of the second wireless relay device, or the synchronization reference switching requirements of the second wireless relay device, the second interval period being different from the first interval period. The apparatus further includes: wherein, the unit for transmitting communication signals is further configured to send a message indicating the first interval period to the first wireless relay device; send a message indicating the second interval period to the second wireless relay device; communicate with the first wireless relay device based on the first interval period; and communicate with the second wireless relay device based on the second interval period. The apparatus further includes: wherein, the unit for transmitting communication signals is further configured to switch from a normal cyclic prefix to an extended cyclic prefix based on at least one of the following: the capability parameters of one or more wireless relay devices, the transmit-receive switching requirements of one or more wireless relay devices, the synchronization reference switching requirements of one or more wireless relay devices, or the synchronization reference of one or more wireless relay devices. The apparatus further includes: wherein, the unit for transmitting communication signals is further configured to transmit a first communication signal to a first wireless relay device among one or more wireless relay devices based on a first synchronization reference of one or more synchronization references; and transmit a second communication signal to a second wireless relay device among one or more wireless relay devices based on a second synchronization reference different from the first synchronization reference among one or more synchronization references. The apparatus further includes: wherein, the unit for transmitting communication signals is further configured to transmit the first communication signal simultaneously with the second communication signal.The apparatus further includes: wherein, the unit for transmitting communication signals is further configured to, during a first time period, transmit a first communication signal in the communication signals with a first wireless relay device among one or more wireless relay devices based on a first synchronization reference of one or more synchronization references; and during a second time period after the first time period, transmit a second communication signal in the communication signals with a second wireless relay device among one or more wireless relay devices based on a second synchronization reference of one or more synchronization references that is different from the first synchronization reference.

[0173] Embodiments of the present disclosure further include an apparatus, the apparatus including: a unit for receiving synchronization information associated with one or more wireless relay devices from one or more wireless relay devices (e.g., transceiver 610 and transceiver 710, and antennas 616 and 716); a unit for determining a synchronization reference adjustment based on at least some of the synchronization information (e.g., processor 602 and processor 702); and a unit for sending a message to direct a first wireless relay device among one or more wireless relay devices to communicate with a second wireless relay device among one or more wireless relay devices based on the synchronization reference adjustment (e.g., transceiver 610 and transceiver 710, and antennas 616 and 716).

[0174] The apparatus further includes: wherein, the unit for receiving synchronization information is further configured to receive at least one of frequency information associated with the synchronization reference of one or more wireless relay devices or timing information associated with the synchronization reference of one or more wireless relay devices. The apparatus further includes: wherein, the message includes a synchronization reference adjustment, and the synchronization reference modulation includes at least one of an interval period, a cyclic prefix configuration, a timing synchronization adjustment, a frequency synchronization adjustment, a transmission timing adjustment, or a reception timing adjustment. The apparatus further includes: a unit for receiving a report from one or more wireless relay devices including at least one of the following: capability information of one or more wireless relay devices, scheduling information of one or more wireless relay devices, transmit-receive switching requirements of one or more wireless relay devices, synchronization reference switching requirements of one or more wireless relay devices, or a priority level associated with the synchronization reference source of one or more wireless relay devices; and a unit for determining at least one of an interval period or a cyclic prefix configuration for the first wireless relay device to communicate with the second wireless relay device based on the report (e.g., processor 602 and processor 702).

[0175] As will now be appreciated by those skilled in the art, and depending on the particular application at hand, many modifications, substitutions, and variations can be made in and to the materials, apparatus, configurations, and methods of use of the devices of the present disclosure without departing from its spirit and scope of protection. In view of this, the scope of protection of the present disclosure should not be limited to the specific embodiments shown and described herein, as they are only some examples thereof, but should be commensurate entirely with the appended claims and their functional equivalents hereinafter.

Claims

1. A method for wireless communication, comprising: receiving, by a first wireless communication device, synchronization information associated with one or more wireless relay devices from the one or more wireless relay devices of a wireless network; determining, by the first wireless communication device, an uplink transmission timing adjustment for a second wireless communication device among the one or more wireless relay devices based on at least some of the synchronization information; and sending, by the first wireless communication device, a message for guiding the second wireless communication device to transmit a downlink message with a third wireless communication device among the one or more wireless relay devices based on the uplink transmission timing adjustment.

2. The method according to claim 1, wherein, The determining includes: determining, by the first wireless communication device, the uplink transmission timing adjustment to align a downlink (DL) transmission of the one or more wireless relay devices to a common DL transmission timing reference.

3. The method according to claim 1, wherein, The determining includes: determining, by the first wireless communication device, the uplink transmission timing adjustment to align a DL transmission timing reference of the second wireless communication device to an uplink (UL) transmission timing reference of the second wireless communication device.

4. The method according to claim 1, wherein The determining includes: determining, by the first wireless communication device, the uplink transmission timing adjustment to align a DL transmission timing reference of the second wireless communication device to a DL reception timing reference of the second wireless communication device.

5. The method according to claim 1, wherein, The determining includes: determining, by the first wireless communication device, the uplink transmission timing adjustment based on at least one of a timing reference of the second wireless communication device for receiving a DL communication signal from a fourth wireless communication device of the wireless network or a timing reference of the second wireless communication device for receiving a DL communication signal from a fifth wireless communication device of the wireless network.

6. The method according to claim 1, further comprising: receiving, by the first wireless communication device, one or more reports, the one or more reports including at least one of capability information of a wireless relay device among the one or more wireless relay devices, scheduling information of a wireless relay device among the one or more wireless relay devices, a transmit-receive handover requirement of a wireless relay device among the one or more wireless relay devices, or a synchronization reference handover requirement of a wireless relay device among the one or more wireless relay devices, wherein the determining is based on the one or more reports.

7. The method according to claim 1, wherein The first wireless communication device is at a next uplink jump from the second wireless communication device.

8. An apparatus, comprising: a transceiver; and a processor communicatively coupled to the transceiver, wherein the apparatus is configured to: receive synchronization information associated with one or more wireless relay devices from the one or more wireless relay devices of a wireless network; determine an uplink transmission timing adjustment for a first wireless communication device among the one or more wireless relay devices based on at least some of the synchronization information, The transceiver is further configured to send a message for instructing the first wireless communication device to transmit a downlink message to a second wireless communication device among the one or more wireless relay devices based on the uplink transmission timing adjustment.

9. The device according to claim 8, wherein, The apparatus is further configured to determine the uplink transmission timing adjustment by: determining the uplink transmission timing adjustment to align the downlink (DL) transmissions of the one or more wireless relay devices to a common DL transmission timing reference.

10. The apparatus according to claim 8, wherein, The apparatus is further configured to determine the uplink transmission timing adjustment by: determining the uplink transmission timing adjustment to align the downlink (DL) transmission timing reference of the first wireless communication device to the uplink (UL) transmission timing reference of the first wireless communication device.

11. The apparatus according to claim 8, wherein, The apparatus is further configured to determine the uplink transmission timing adjustment by: determining the uplink transmission timing adjustment to align the downlink (DL) transmission timing reference of the first wireless communication device to the downlink (DL) reception timing reference of the first wireless communication device.

12. The device according to claim 8, wherein, The apparatus is further configured to determine the uplink transmission timing adjustment by: determining the uplink transmission timing adjustment based on at least one of the timing reference of the first wireless communication device for receiving a downlink (DL) communication signal from a third wireless communication device of the wireless network or the timing reference of the first wireless communication device for receiving a DL communication signal from a fourth wireless communication device of the wireless network.

13. The device according to claim 8, wherein, The apparatus is further configured to: receive one or more reports, the one or more reports including at least one of the capability information of a wireless relay device among the one or more wireless relay devices, the scheduling information of a wireless relay device among the one or more wireless relay devices, the transmit-receive handover requirement of a wireless relay device among the one or more wireless relay devices, or the synchronization reference handover requirement of a wireless relay device among the one or more wireless relay devices, wherein the transmission timing adjustment is determined based on the one or more reports.

14. The apparatus according to claim 8, wherein The apparatus is at the next uplink jump of the first wireless communication device.

15. The apparatus according to claim 8, wherein, The second wireless communication device is at the next downlink jump of the first wireless communication device.

16. An apparatus, comprising: a unit for receiving synchronization information associated with one or more wireless relay devices of a wireless network from the one or more wireless relay devices; a unit for determining an uplink transmission timing adjustment for a first wireless communication device among the one or more wireless relay devices based on at least some of the synchronization information; and a unit for sending a message for instructing the first wireless communication device to transmit a downlink message to a second wireless communication device among the one or more wireless relay devices based on the uplink transmission timing adjustment.

17. The apparatus according to claim 16, wherein, The unit for determining includes: A unit for determining the uplink transmission timing adjustment to align the downlink (DL) transmissions of the one or more wireless relay devices to a common DL transmission timing reference.

18. The apparatus according to claim 16, wherein, The unit for determining includes: A unit for determining the uplink transmission timing adjustment to align the DL transmission timing reference of the first wireless communication device to the uplink (UL) transmission timing reference of the first wireless communication device.

19. The apparatus according to claim 16, wherein, The unit for determining includes: A unit for determining the uplink transmission timing adjustment to align the DL transmission timing reference of the first wireless communication device to the DL reception timing reference of the first wireless communication device.

20. The apparatus according to claim 16, wherein, The unit for determining includes: A unit for determining the uplink transmission timing adjustment based on at least one of the timing reference of the first wireless communication device for receiving the DL communication signal of the third wireless communication device from the wireless network or the timing reference of the first wireless communication device for receiving the DL communication signal of the fourth wireless communication device from the wireless network.

21. The apparatus according to claim 16, further comprising: A unit for receiving one or more reports, the one or more reports including at least one of the capability information of a wireless relay device among the one or more wireless relay devices, the scheduling information of a wireless relay device among the one or more wireless relay devices, the transmit-receive switching requirement of a wireless relay device among the one or more wireless relay devices, or the synchronization reference switching requirement of a wireless relay device among the one or more wireless relay devices, wherein the unit for determining is configured to determine the transmission timing adjustment based on the one or more reports.

22. The apparatus according to claim 16, wherein The apparatus is at the next uplink jump of the first wireless communication device.

23. The apparatus according to claim 16, wherein The second wireless communication device is at the next downlink jump of the first wireless communication device.

24. A non-transitory computer-readable medium having program code recorded thereon, the program code including: Code for causing a first wireless communication device to receive synchronization information associated with one or more wireless relay devices from the wireless network; Code for causing the first wireless communication device to determine an uplink transmission timing adjustment for a second wireless communication device among the one or more wireless relay devices based on at least some of the synchronization information; and Code for causing the first wireless communication device to send a message for guiding the second wireless communication device to transmit a downlink message to a third wireless communication device among the one or more wireless relay devices based on the uplink transmission timing adjustment.

25. The non-transitory computer-readable medium according to claim 24, wherein, The code for causing the first wireless communication device to determine the transmission timing adjustment includes: The first wireless communication device determines the uplink transmission timing adjustment to align the DL transmissions of the one or more wireless relay devices to a common DL transmission timing reference.

26. The non-transitory computer-readable medium according to claim 24, wherein, The first wireless communication device is at the next uplink hop of the second wireless communication device.

27. A method for wireless communication, comprising: Receiving, by a first wireless communication device of a multi-hop wireless network, an uplink transmission timing adjustment command, the uplink transmission timing adjustment command indicating a timing advance between an uplink of the first wireless communication device and a downlink of a second wireless communication device, the second wireless communication device being at the next uplink hop of the multi-hop wireless network from the first wireless communication device; Sending, by the first wireless communication device, a first communication signal including backhaul data in an uplink direction to the second wireless communication device at a transmission time, the transmission time being at least based on the uplink transmission timing adjustment command; And Sending, by the first wireless communication device, a second communication signal in a downlink direction to a third wireless communication device of the multi-hop wireless network at the next downlink hop from the first wireless communication device, at least based on the uplink transmission timing adjustment command.

28. The method according to claim 27, wherein, The sending of the second communication signal includes: Sending, by the first wireless communication device, the second communication signal including access data to the third wireless communication device.

29. The method according to claim 27, further comprising: Receiving, by the first wireless communication device, a third communication signal including backhaul data from the third wireless communication device.

30. The method according to claim 27, further comprising: Sending, by the first wireless communication device, an uplink UL communication signal to the second wireless communication device, wherein the sending of the second communication signal to the third wireless communication device is based on a timing reference determined with respect to the transmission time of the UL communication signal.

31. The method according to claim 27, further comprising: Receiving, by the first wireless communication device, a downlink DL communication signal from the second wireless communication device, wherein the sending of the second communication signal to the third wireless communication device is based on a timing reference determined with respect to the transmission time of the DL communication signal.

32. The method according to claim 31, further comprising: Determining, by the first wireless communication device, the timing reference based on the reception time of the DL communication signal at the first wireless communication device and the uplink transmission timing adjustment command.

33. The method according to claim 27, further comprising: Receiving, by the first wireless communication device, a downlink DL communication signal from the second wireless communication device, wherein the sending of the second communication signal is based on a timing reference determined with respect to the reception time of the DL communication signal.

34. The method according to claim 27, further comprising: Receiving, by the first wireless communication device, a first downlink DL communication signal from the second wireless communication device; And Receiving, by the first wireless communication device, a second DL communication signal from a fourth wireless communication device of the multi-hop wireless network, Wherein, the sending of the second communication signal is based on at least one of the reception time of the first DL communication signal or the reception time of the second DL communication signal.

35. The method according to claim 27, further comprising: receiving, by the first wireless communication device, a second transmission timing adjustment command for sending an uplink UL communication signal to a fourth wireless communication device of the multi-hop wireless network; and sending, by the first wireless communication device, the UL communication signal including backhaul data to the fourth wireless communication device based on the second transmission timing adjustment command, wherein the sending of the second communication signal is based on at least one of the uplink transmission timing adjustment command or the second transmission timing adjustment command.

36. The method according to claim 27, wherein, The receiving includes: receiving, by the first wireless communication device, the uplink transmission timing adjustment command from a second wireless communication device.

37. The method according to claim 27, wherein The receiving includes: receiving, by the first wireless communication device, the uplink transmission timing adjustment command from a central entity.

38. The method according to claim 27, further comprising: sending, by the first wireless communication device, a second transmission adjustment command to a third wireless communication device of the multi-hop wireless network; and receiving, by the first wireless communication device, an uplink UL communication signal from the third wireless communication device based on the second transmission adjustment command.

39. The method according to claim 27, further comprising: transmitting, by the first wireless communication device, a third communication signal to the third wireless communication device based on a first timing reference; and transmitting, by the first wireless communication device, a fourth communication signal to a fourth wireless communication device based on a second timing reference different from the first timing reference.

40. An apparatus, comprising: a transceiver configured to: receive an uplink transmission timing adjustment command indicating a timing advance between an uplink of the apparatus and a downlink of a first wireless communication device, wherein the apparatus is associated with a multi-hop wireless network, and wherein the first wireless communication device is at the next uplink hop from the apparatus in the multi-hop wireless network; send, at a transmission time, a first communication signal including backhaul data in an uplink direction to the first wireless communication device of the multi-hop wireless network, the transmission time being at least based on the uplink transmission timing adjustment command; and send, at least based on the uplink transmission timing adjustment command, a second communication signal in a downlink direction to a second wireless communication device of the multi-hop wireless network at the next downlink hop from the first wireless communication device.

41. The apparatus according to claim 40, wherein, The second communication signal includes access data.

42. The apparatus according to claim 40, wherein, The transceiver is further configured to: receive a third communication signal including backhaul data from the second wireless communication device.

43. The apparatus according to claim 40, wherein, The transceiver is further configured to: send an uplink UL communication signal to the first wireless communication device Wherein, the second communication signal is sent based on a timing reference determined with respect to the transmission time of the UL communication signal.

44. The apparatus according to claim 40, wherein, The transceiver is further configured to: Receive a DL communication signal from the first wireless communication device, Wherein, the second communication signal is sent based on a timing reference determined with respect to the transmission time of the DL communication signal.

45. The apparatus according to claim 44, further comprising a processor configured to: Determine the timing reference based on the reception time of the DL communication signal at the apparatus and the uplink transmission timing adjustment command.

46. The apparatus according to claim 40, wherein, The transceiver is further configured to: Receive a DL communication signal from the first wireless communication device, Wherein, the second communication signal is sent based on a timing reference determined with respect to the reception time of the DL communication signal.

47. The apparatus according to claim 40, wherein The transceiver is further configured to: Receive a first DL communication signal from the first wireless communication device; and Receive a second DL communication signal from a third wireless communication device of the multi-hop wireless network, Wherein, the second communication signal is sent based on at least one of the reception time of the first DL communication signal or the reception time of the second DL communication signal.

48. The apparatus according to claim 40, wherein, The transceiver is further configured to: Receive a second transmission timing adjustment command; and Based on the second transmission timing adjustment command, send an uplink UL communication signal including backhaul data to a third wireless communication device of the multi-hop wireless network, Wherein, the second communication signal is sent based on at least one of the uplink transmission timing adjustment command or the second transmission timing adjustment command.

49. The apparatus according to claim 40, wherein, The uplink transmission timing adjustment command is received from the first wireless communication device.

50. The apparatus according to claim 40, wherein, The uplink transmission timing adjustment command is received from a central entity.

51. The apparatus according to claim 40, wherein, The apparatus is a base station, and the transceiver is further configured to: Send a second transmission adjustment command to the second wireless communication device of the multi-hop wireless network; And Based on the second transmission adjustment command, receive an uplink UL communication signal from the second wireless communication device.

52. The apparatus according to claim 40, wherein, The transceiver is further configured to: Transmit a third communication signal with the second wireless communication device based on a first timing reference; and Transmit a fourth communication signal with a third wireless communication device based on a second timing reference different from the first timing reference.

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