# Patent

## Title
Direct transport block (TB) forwarding in relaying operations

## Abstract

Certain aspects of the present disclosure provide techniques for direct transport block (TB) forwarding in relaying operations. A method that may be performed by a relay node includes receiving, from a source node, an indication to directly forward a TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a Physical (PHY) layer and a hybrid automatic repeat request (HARM) portion of a Media Access Control (MAC) layer in a protocol stack of the relay node and directly forwarding the TB to the destination node based, at least in part, on the indication.

## Background
CROSS-REFERENCE TO RELATED APPLICATION(S)
This application claims benefit of and priority to U.S. Provisional Application No. 63/105,164, filed Oct. 23, 2020 which is hereby assigned to the assignee hereof and hereby expressly incorporated by reference herein in its entirety as if fully set forth below and for all applicable purposes.


BACKGROUND
Field of the Disclosure
Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for direct transport block (TB) forwarding in relaying operations.
Description of Related Art
Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasts, etc. These wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple-access systems include 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, LTE Advanced (LTE-A) systems, code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems, to name a few.
In some examples, a wireless multiple-access communication system may include a number of base stations (BSs), which are each capable of simultaneously supporting communication for multiple communication devices, otherwise known as user equipments (UEs). In an LTE or LTE-A network, a set of one or more base stations may define an eNodeB (eNB). In other examples (e.g., in a next generation, a new radio (NR), or 5G network), a wireless multiple access communication system may include a number of distributed units (DUs) (e.g., edge units (EUs), edge nodes (ENs), radio heads (RHs), smart radio heads (SRHs), transmission reception points (TRPs), etc.) in communication with a number of central units (CUs) (e.g., central nodes (CNs), access node controllers (ANCs), etc.), where a set of one or more DUs, in communication with a CU, may define an access node (e.g., which may be referred to as a BS, 5G NB, next generation NodeB (gNB or gNodeB), transmission reception point (TRP), etc.). A BS or DU may communicate with a set of UEs on downlink channels (e.g., for transmissions from a BS or DU to a UE) and uplink channels (e.g., for transmissions from a UE to BS or DU).
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. NR (e.g., new radio or 5G) is an example of an emerging telecommunication standard. NR is a set of enhancements to the LTE mobile standard promulgated by 3GPP. NR is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using OFDMA with a cyclic prefix (CP) on the downlink (DL) and on the uplink (UL). To these ends, NR supports beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation.
However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in NR and LTE technology. These improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.
SUMMARY
The systems, methods, and devices of the disclosure each have several aspects, no single one of which is solely responsible for its desirable attributes. After considering this discussion, and particularly after reading the section entitled “Detailed Description” one will understand how the features of this disclosure provide advantages that include improved communications between access points and stations in a wireless network.
Certain aspects of the subject matter described in this disclosure provide a method for wireless communication by a source node. The method generally includes receiving, from a source node, an indication to directly forward a transport block (TB) to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a Physical (PHY) layer and a hybrid automatic repeat request (HARQ) portion of a Media Access Control (MAC) layer in a protocol stack of the relay node. The method generally includes directly forwarding the TB to the destination node based, at least in part, on the indication.
Certain aspects of the subject matter described in this disclosure provide a method for wireless communication by a source node. The method generally includes transmitting, to a relay node, a grant for a TB. The method generally includes transmitting, to the relay node, an indication to directly forward the TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a PHY layer and a HARQ portion of a MAC layer in a protocol stack of the relay node. The method generally includes transmitting, to the relay node, the TB in accordance with the grant.
Certain aspects of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication by a relay node. The apparatus generally includes: a memory; and at least one processor coupled to the memory, the at least one processor being configured to: receive, from a source node, an indication to directly forward a TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a PHY layer and a HARQ portion of a MAC layer in a protocol stack of the relay node and directly forward the TB to the destination node based, at least in part, on the indication.
Certain aspects of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication by a source node. The apparatus generally includes: a memory; and at least one processor coupled to the memory, the at least one processor being configured to: transmit, to a relay node, a grant for a TB; transmit, to the relay node, an indication to directly forward the TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a PHY layer and a HARQ portion of a MAC layer in a protocol stack of the relay node; and transmit, to the relay node, the TB in accordance with the grant.
Certain aspects of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication by a relay node. The apparatus generally includes: means for receiving, from a source node, an indication to directly forward a TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a PHY layer and a HARQ portion of a MAC layer in a protocol stack of the relay node and means for directly forwarding the TB to the destination node based, at least in part, on the indication.
Certain aspects of the subject matter described in this disclosure can be implemented in an apparatus for wireless communication by a source node. The apparatus generally includes: means for transmitting, to a relay node, a grant for a TB; means for transmitting, to the relay node, an indication to directly forward the TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a PHY layer and a HARQ portion of a MAC layer in a protocol stack of the relay node; and means for transmitting, to the relay node, the TB in accordance with the grant.
Certain aspects of the subject matter described in this disclosure can be implemented in a computer-readable medium having instructions stored thereon to cause a relay node to: receive, from a source node, an indication to directly forward a TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a PHY layer and a HARQ portion of a MAC layer in a protocol stack of the relay node and directly forward the TB to the destination node based, at least in part, on the indication.
Certain aspects of the subject matter described in this disclosure can be implemented in a computer-readable medium having instructions stored thereon to cause a source node to: transmit, to a relay node, a grant for a TB; transmit, to the relay node, an indication to directly forward the TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a PHY layer and a HARQ portion of a MAC layer in a protocol stack of the relay node; and transmit, to the relay node, the TB in accordance with the grant.
To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the appended drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed.



BRIEF DESCRIPTION OF THE DRAWINGS
So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and the description may admit to other equally effective aspects.
FIG. 1 is a block diagram conceptually illustrating an example telecommunications system, in accordance with certain aspects of the present disclosure.
FIG. 2 is a block diagram illustrating an example architecture of a distributed radio access network (RAN), in accordance with certain aspects of the present disclosure.
FIG. 3 is a block diagram showing examples for implementing a communication protocol stack in the example RAN architecture, in accordance with certain aspects of the present disclosure.
FIG. 4 is a block diagram conceptually illustrating a design of an example base station (BS) and user equipment (UE), in accordance with certain aspects of the present disclosure.
FIG. 5 illustrates an example of a frame format for a telecommunication system, in accordance with certain aspects of the present disclosure.
FIG. 6 illustrates an example relaying operation where a transport block (TB) size supported by a link between a source node and a relay node is not supported by a link between the relay node and a destination node.
FIG. 7 illustrates example packet processing through a communication protocol stack, in accordance with certain aspects of the present disclosure.
FIG. 8 illustrates an example relaying operation where a source-relay link and a relay-destination link support the same TB size, in accordance with certain aspects of the present disclosure.
FIG. 9 is a flow diagram illustrating example operations for wireless communication by a relay node, in accordance with certain aspects of the present disclosure.
FIG. 10 is a flow diagram illustrating example operations for wireless communication by a source node, in accordance with certain aspects of the present disclosure.
FIG. 11 is a call flow diagram illustrating example signaling for relaying operations in sidelink (SL) transmission mode 1, in accordance with aspects of the present disclosure.
FIG. 12 illustrates a communications device that may include various components configured to perform operations for the techniques disclosed herein in accordance with aspects of the present disclosure.
FIG. 13 illustrates a communications device that may include various components configured to perform operations for the techniques disclosed herein in accordance with aspects of the present disclosure.



To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one aspect may be beneficially utilized on other aspects without specific recitation.
DETAILED DESCRIPTION
Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for relaying operations. As will be described herein, direct transport block (TB) forwarding may be enabled in relaying operations wherein a TB is transmitted to a destination node without going through the entire protocol stack of the relay node. Accordingly, a TB may be transmitted to a destination node through only a Physical (PHY) layer and a portion of the Media Access Control (MAC) layer. In aspects of the present disclosure, the TB is forwarded through the PHY layer and the hybrid automatic repeat request (HARQ) portion of the MAC layer in a protocol stack of a relay node.
The following description provides examples, and is not limiting of the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of elements discussed without departing from the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some examples may be combined in some other examples. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to, or other than, the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim. The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects.
The techniques described herein may be used for various wireless communication technologies, such as LTE, CDMA, TDMA, FDMA, OFDMA, SC-FDMA and other networks. The terms “network” and “system” are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM). An OFDMA network may implement a radio technology such as NR (e.g. 5G RA), 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 Universal Mobile Telecommunication System (UMTS).
New Radio (NR) is an emerging wireless communications technology under development in conjunction with the 5G Technology Forum (5GTF). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are 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 may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. For clarity, while aspects may be described herein using terminology commonly associated with 3G and/or 4G wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems, such as 5G and later, including NR technologies.
New radio (NR) access (e.g., 5G technology) may support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g., 80 MHz or beyond), millimeter wave (mmW) targeting high carrier frequency (e.g., 25 GHz or beyond), massive machine type communications MTC (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra-reliable low-latency communications (URLLC). These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTI) to meet respective quality of service (QoS) requirements. In addition, these services may co-exist in the same subframe.
Example Wireless Communications System
FIG. 1 illustrates an example wireless communication network 100 in which aspects of the present disclosure may be performed. For example, the wireless communication network 100 may be a New Radio (NR) or 5G network. For example, as shown in FIG. 1, the UE 120a has a relaying manager that may be configured for receiving, from a source node, an indication to directly forward a transport block (TB) to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a Physical (PHY) layer and a hybrid automatic repeat request (HARQ) portion of a Media Access Control (MAC) layer in a protocol stack of the relay node and directly forwarding the TB to the destination node based, at least in part, on the indication, according to aspects described herein. For example, as shown in FIG. 1, the BS 110a has a relaying manager that may be configured for transmitting, to a relay node, an indication to directly forward a TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a PHY layer and a HARQ portion of a MAC layer in a protocol stack of the relay node, according to aspects described herein.
As illustrated in FIG. 1, the wireless communication network 100 may include a number of base stations (BSs) 110 and other network entities. A BS may be a station that communicates with user equipments (UEs). Each BS 110 may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to a coverage area of a Node B (NB) and/or a NB subsystem serving this coverage area, depending on the context in which the term is used. In NR systems, the term “cell” and next generation NodeB (gNB or gNodeB), NR BS, 5G NB, access point (AP), or transmission reception point (TRP) may be interchangeable. In some examples, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile BS. In some examples, the base stations may be interconnected to one another and/or to one or more other base stations or network nodes (not shown) in wireless communication network 100 through various types of backhaul interfaces, such as a direct physical connection, a wireless connection, a virtual network, or the like using any suitable transport network.
In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular radio access technology (RAT) and may operate on one or more frequencies. A RAT may also be referred to as a radio technology, an air interface, etc. A frequency may also be referred to as a carrier, a subcarrier, a frequency channel, a tone, a subband, etc. Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks may be deployed.
A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or other types of cells. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having an association with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG), UEs for users in the home, etc.). A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. In the example shown in FIG. 1, the BSs 110a, 110b and 110c may be macro BSs for the macro cells 102a, 102b and 102c, respectively. The BS 110x may be a pico BS for a pico cell 102x. The BSs 110y and 110z may be femto BSs for the femto cells 102y and 102z, respectively. ABS may support one or multiple (e.g., three) cells.
Wireless communication network 100 may also include relay stations. A relay station is a station that receives a transmission of data and/or other information from an upstream station (e.g., a BS or a UE) and transmits a transmission of the data and/or other information to a downstream station (e.g., a UE or a BS). A relay station may also be a UE that relays transmissions for other UEs or BSs. In the example shown in FIG. 1, a relay station 110r may communicate with the BS 110a and a UE 120r in order to facilitate communication between the BS 110a and the UE 120r. UE 120a may also be a relay station used to communicate with BS 110a and a UE 120s in order to facilitate communication between the BS 110a and the UE 120s. The relay 120s may be located within the coverage area 102a. A relay station may also be referred to as a relay BS, a relay UE, a relay, a relay node etc.
Wireless communication network 100 may be a heterogeneous network that includes BSs of different types, e.g., macro BS, pico BS, femto BS, relays, etc. These different types of BSs may have different transmit power levels, different coverage areas, and different impact on interference in the wireless communication network 100. For example, macro BS may have a high transmit power level (e.g., 20 Watts) whereas pico BS, femto BS, and relays may have a lower transmit power level (e.g., 1 Watt).
Wireless communication network 100 may support synchronous or asynchronous operation. For synchronous operation, the BSs may have similar frame timing, and transmissions from different BSs may be approximately aligned in time. For asynchronous operation, the BSs may have different frame timing, and transmissions from different BSs may not be aligned in time. The techniques described herein may be used for both synchronous and asynchronous operation.
A network controller 130 may couple to a set of BSs and provide coordination and control for these BSs. The network controller 130 may communicate with the BSs 110 via a backhaul. The BSs 110 may also communicate with one another (e.g., directly or indirectly) via wireless or wireline backhaul.
The UEs 120 (e.g., 120x, 120y, etc.) may be dispersed throughout the wireless communication network 100, and each UE may be stationary or mobile. A UE may also be referred to as a mobile station, a terminal, an access terminal, a subscriber unit, a station, a Customer Premises Equipment (CPE), a cellular phone, a smart phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet computer, a camera, a gaming device, a netbook, a smartbook, an ultrabook, an appliance, a medical device or medical equipment, a biometric sensor/device, a wearable device such as a smart watch, smart clothing, smart glasses, a smart wrist band, smart jewelry (e.g., a smart ring, a smart bracelet, etc.), an entertainment device (e.g., a music device, a video device, a satellite radio, etc.), a vehicular component or sensor, a smart meter/sensor, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium. Some UEs may be considered machine-type communication (MTC) devices or evolved MTC (eMTC) devices. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., that may communicate with a BS, another device (e.g., remote device), or some other entity. A wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet-of-Things (IoT) devices, which may be narrowband IoT (NB-IoT) devices.
Certain wireless networks (e.g., LTE) utilize orthogonal frequency division multiplexing (OFDM) on the downlink and single-carrier frequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM partition the system bandwidth into multiple (K) orthogonal subcarriers, which are also commonly referred to as tones, bins, etc. Each subcarrier may be modulated with data. In general, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers may be fixed, and the total number of subcarriers (K) may be dependent on the system bandwidth. For example, the spacing of the subcarriers may be 15 kHz and the minimum resource allocation (called a “resource block” (RB)) may be 12 subcarriers (or 180 kHz). Consequently, the nominal Fast Fourier Transfer (FFT) size may be equal to 128, 256, 512, 1024 or 2048 for system bandwidth of 1.25, 2.5, 5, 10, or 20 megahertz (MHz), respectively. The system bandwidth may also be partitioned into subbands. For example, a subband may cover 1.08 MHz (i.e., 6 resource blocks), and there may be 1, 2, 4, 8, or 16 subbands for system bandwidth of 1.25, 2.5, 5, 10 or 20 MHz, respectively.
While aspects of the examples described herein may be associated with LTE technologies, aspects of the present disclosure may be applicable with other wireless communications systems, such as NR. NR may utilize OFDM with a CP on the uplink and downlink and include support for half-duplex operation using TDD. Beamforming may be supported and beam direction may be dynamically configured. MIMO transmissions with precoding may also be supported. MIMO configurations in the DL may support up to 8 transmit antennas with multi-layer DL transmissions up to 8 streams and up to 2 streams per UE. Multi-layer transmissions with up to 2 streams per UE may be supported. Aggregation of multiple cells may be supported with up to 8 serving cells.
In some examples, access to the air interface may be scheduled. A scheduling entity (e.g., a BS) allocates resources for communication among some or all devices and equipment within its service area or cell. The scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communication, subordinate entities utilize resources allocated by the scheduling entity. Base stations are not the only entities that may function as a scheduling entity. In some examples, a UE may function as a scheduling entity and may schedule resources for one or more subordinate entities (e.g., one or more other UEs), and the other UEs may utilize the resources scheduled by the UE for wireless communication. In some examples, a UE may function as a scheduling entity in a peer-to-peer (P2P) network, and/or in a mesh network. In a mesh network example, UEs may communicate directly with one another in addition to communicating with a scheduling entity.
In FIG. 1, a solid line with double arrows indicates desired transmissions between a UE and a serving BS, which is a BS designated to serve the UE on the downlink and/or uplink. A finely dashed line with double arrows indicates interfering transmissions between a UE and a BS.
FIG. 2 illustrates an example architecture of a distributed Radio Access Network (RAN) 200, which may be implemented in the wireless communication network 100 illustrated in FIG. 1. As shown in FIG. 2, the distributed RAN includes Core Network (CN) 202 and Access Node 208.
The CN 202 may host core network functions. CN 202 may be centrally deployed. CN 202 functionality may be offloaded (e.g., to advanced wireless services (AWS)), in an effort to handle peak capacity. The CN 202 may include the Access and Mobility Management Function (AMF) 204 and User Plane Function (UPF) 206. The AMF 204 and UPF 206 may perform one or more of the core network functions.
The AN 208 may communicate with the CN 202 (e.g., via a backhaul interface). The AN 208 may communicate with the AMF 204 via an N2 (e.g., NG-C) interface. The AN 208 may communicate with the UPF 208 via an N3 (e.g., NG-U) interface. The AN 208 may include a central unit-control plane (CU-CP) 210, one or more central unit-user plane (CU-UPs) 212, one or more distributed units (DUs) 214-218, and one or more Antenna/Remote Radio Units (AU/RRUs) 220-224. The CUs and DUs may also be referred to as gNB-CU and gNB-DU, respectively. One or more components of the AN 208 may be implemented in a gNB 226. The AN 208 may communicate with one or more neighboring gNBs.
The CU-CP 210 may be connected to one or more of the DUs 214-218. The CU-CP 210 and DUs 214-218 may be connected via a F1-C interface. As shown in FIG. 2, the CU-CP 210 may be connected to multiple DUs, but the DUs may be connected to only one CU-CP. Although FIG. 2 only illustrates one CU-UP 212, the AN 208 may include multiple CU-UPs. The CU-CP 210 selects the appropriate CU-UP(s) for requested services (e.g., for a UE). The CU-UP(s) 212 may be connected to the CU-CP 210. For example, the DU-UP(s) 212 and the CU-CP 210 may be connected via an E1 interface. The CU-CP(s) 212 may be connected to one or more of the DUs 214-218. The CU-UP(s) 212 and DUs 214-218 may be connected via a F1-U interface. As shown in FIG. 2, the CU-CP 210 may be connected to multiple CU-UPs, but the CU-UPs may be connected to only one CU-CP.
A DU, such as DUs 214, 216, and/or 218, may host one or more TRP(s) (transmit/receive points, which may include an Edge Node (EN), an Edge Unit (EU), a Radio Head (RH), a Smart Radio Head (SRH), or the like). A DU may be located at edges of the network with radio frequency (RF) functionality. A DU may be connected to multiple CU-UPs that are connected to (e.g., under the control of) the same CU-CP (e.g., for RAN sharing, radio as a service (RaaS), and service specific deployments). DUs may be configured to individually (e.g., dynamic selection) or jointly (e.g., joint transmission) serve traffic to a UE. Each DU 214-216 may be connected with one of AU/RRUs 220-224.
The CU-CP 210 may be connected to multiple DU(s) that are connected to (e.g., under control of) the same CU-UP 212. Connectivity between a CU-UP 212 and a DU may be established by the CU-CP 210. For example, the connectivity between the CU-UP 212 and a DU may be established using Bearer Context Management functions. Data forwarding between CU-UP(s) 212 may be via a Xn-U interface.
The distributed RAN 200 may support fronthauling solutions across different deployment types. For example, the RAN 200 architecture may be based on transmit network capabilities (e.g., bandwidth, latency, and/or jitter). The distributed RAN 200 may share features and/or components with LTE. For example, AN 208 may support dual connectivity with NR and may share a common fronthaul for LTE and NR. The distributed RAN 200 may enable cooperation between and among DUs 214-218, for example, via the CU-CP 212. An inter-DU interface may not be used.
Logical functions may be dynamically distributed in the distributed RAN 200. As will be described in more detail with reference to FIG. 3, the Radio Resource Control (RRC) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, Medium Access Control (MAC) layer, Physical (PHY) layers, and/or Radio Frequency (RF) layers may be adaptably placed, in the AN and/or UE.
FIG. 3 illustrates a diagram showing examples for implementing a communications protocol stack 300 in a RAN (e.g., such as the RAN 200), according to aspects of the present disclosure. The illustrated communications protocol stack 300 may be implemented by devices operating in a wireless communication system, such as a 5G NR system (e.g., the wireless communication network 100). In various examples, the layers of the protocol stack 300 may be implemented as separate modules of software, portions of a processor or ASIC, portions of non-collocated devices connected by a communications link, or various combinations thereof. Collocated and non-collocated implementations may be used, for example, in a protocol stack for a network access device or a UE. As shown in FIG. 3, the system may support various services over one or more protocols. One or more protocol layers of the protocol stack 300 may be implemented by the AN and/or the UE.
As shown in FIG. 3, the protocol stack 300 is split in the AN (e.g., AN 208 in FIG. 2). The RRC layer 305, PDCP layer 310, RLC layer 315, MAC layer 320, PHY layer 325, and RF layer 530 may be implemented by the AN. For example, the CU-CP (e.g., CU-CP 210 in FIG. 2) and the CU-UP e.g., CU-UP 212 in FIG. 2) each may implement the RRC layer 305 and the PDCP layer 310. A DU (e.g., DUs 214-218 in FIG. 2) may implement the RLC layer 315 and MAC layer 320. The AU/RRU (e.g., AU/RRUs 220-224 in FIG. 2) may implement the PHY layer(s) 325 and the RF layer(s) 330. The PHY layers 325 may include a high PHY layer and a low PHY layer.
The UE may implement the entire protocol stack 300 (e.g., the RRC layer 305, the PDCP layer 310, the RLC layer 315, the MAC layer 320, the PHY layer(s) 325, and the RF layer(s) 330).
FIG. 4 illustrates example components of BS 110 and UE 120 (as depicted in FIG. 1), which may be used to implement aspects of the present disclosure. For example, antennas 452, processors 466, 458, 464, and/or controller/processor 480 of the UE 120 and/or antennas 434, processors 420, 430, 438, and/or controller/processor 440 of the BS 110 may be used to perform the various techniques and methods described herein. For example, as shown in FIG. 4, the processor 440 has a relaying manager that may be configured for transmitting, to the relay node, an indication to directly forward a TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a PHY layer and a HARQ portion of a MAC layer in a protocol stack of the relay node, according to aspects described herein. For example, as shown in FIG. 4, the processor 480 has a relaying manager that may be configured for receiving, from a source node, an indication to directly forward a TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a PHY layer and a HARQ portion of a MAC layer in a protocol stack of the relay node and directly forwarding the TB to the destination node based, at least in part, on the indication, according to aspects described herein.
At the BS 110, a transmit processor 420 may receive data from a data source 412 and control information from a controller/processor 440. The control information may be for the physical broadcast channel (PBCH), physical control format indicator channel (PCFICH), physical hybrid ARQ indicator channel (PHICH), physical downlink control channel (PDCCH), group common PDCCH (GC PDCCH), etc. The data may be for the physical downlink shared channel (PDSCH), etc. The processor 420 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The processor 420 may also generate reference symbols, e.g., for the primary synchronization signal (PSS), secondary synchronization signal (SSS), and cell-specific reference signal (CRS). A transmit (TX) multiple-input multiple-output (MIMO) processor 430 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) 432a through 432t. Each modulator 432 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulators 432a through 432t may be transmitted via the antennas 434a through 434t, respectively.
At the UE 120, the antennas 452a through 452r may receive the downlink signals from the base station 110 and may provide received signals to the demodulators (DEMODs) in transceivers 454a through 454r, respectively. Each demodulator 454 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector 456 may obtain received symbols from all the demodulators 454a through 454r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 458 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 120 to a data sink 460, and provide decoded control information to a controller/processor 480.
On the uplink, at UE 120, a transmit processor 464 may receive and process data (e.g., for the physical uplink shared channel (PUSCH)) from a data source 462 and control information (e.g., for the physical uplink control channel (PUCCH) from the controller/processor 480. The transmit processor 464 may also generate reference symbols for a reference signal (e.g., for the sounding reference signal (SRS)). The symbols from the transmit processor 464 may be precoded by a TX MIMO processor 466 if applicable, further processed by the demodulators in transceivers 454a through 454r (e.g., for SC-FDM, etc.), and transmitted to the base station 110. At the BS 110, the uplink signals from the UE 120 may be received by the antennas 434, processed by the modulators 432, detected by a MIMO detector 436 if applicable, and further processed by a receive processor 438 to obtain decoded data and control information sent by the UE 120. The receive processor 438 may provide the decoded data to a data sink 439 and the decoded control information to the controller/processor 440.
The controllers/processors 440 and 480 may direct the operation at the BS 110 and the UE 120, respectively. The processor 440 and/or other processors and modules at the BS 110 may perform or direct the execution of processes for the techniques described herein. The memories 442 and 482 may store data and program codes for BS 110 and UE 120, respectively. A scheduler 444 may schedule UEs for data transmission on the downlink and/or uplink.
FIG. 5 is a diagram showing an example of a frame format 500 for NR. The transmission timeline for each of the downlink and uplink may be partitioned into units of radio frames. Each radio frame may have a predetermined duration (e.g., 10 ms) and may be partitioned into 10 subframes, each of 1 ms, with indices of 0 through 9. Each subframe may include a variable number of slots depending on the subcarrier spacing. Each slot may include a variable number of symbol periods (e.g., 7 or 14 symbols) depending on the subcarrier spacing. The symbol periods in each slot may be assigned indices. A mini-slot, which may be referred to as a sub-slot structure, refers to a transmit time interval having a duration less than a slot (e.g., 2, 3, or 4 symbols). Each symbol in a slot may indicate a link direction (e.g., DL, UL, or flexible) for data transmission and the link direction for each subframe may be dynamically switched. The link directions may be based on the slot format. Each slot may include DL/UL data as well as DL/UL control information.
In NR, a synchronization signal (SS) block is transmitted. The SS block includes a PSS, a SSS, and a two symbol PBCH. The SS block can be transmitted in a fixed slot location, such as the symbols 0-3 as shown in FIG. 5. The PSS and SSS may be used by UEs for cell search and acquisition. The PSS may provide half-frame timing, the SS may provide the CP length and frame timing. The PSS and SSS may provide the cell identity. The PBCH carries some basic system information, such as downlink system bandwidth, timing information within radio frame, SS burst set periodicity, system frame number, etc. The SS blocks may be organized into SS bursts to support beam sweeping. Further system information such as, remaining minimum system information (RMSI), system information blocks (SIBs), other system information (OSI) can be transmitted on a physical downlink shared channel (PDSCH) in certain subframes. The SS block can be transmitted up to sixty-four times, for example, with up to sixty-four different beam directions for mmW. The up to sixty-four transmissions of the SS block are referred to as the SS burst set. SS blocks in an SS burst set are transmitted in the same frequency region, while SS blocks in different SS bursts sets can be transmitted at different frequency locations.
In some circumstances, two or more subordinate entities (e.g., UEs) may communicate with each other using sidelink signals. Real-world applications of such sidelink communications may include public safety, proximity services, UE-to-network relaying, vehicle-to-vehicle (V2V) communications, Internet of Everything (IoE) communications, IoT communications, mission-critical mesh, and/or various other suitable applications. Generally, a sidelink signal may refer to a signal communicated from one subordinate entity (e.g., UE1) to another subordinate entity (e.g., UE2) without relaying that communication through the scheduling entity (e.g., UE or BS), even though the scheduling entity may be utilized for scheduling and/or control purposes. In some examples, the sidelink signals may be communicated using a licensed spectrum (unlike wireless local area networks, which may use an unlicensed spectrum).
A UE may operate in various radio resource configurations, including a configuration associated with transmitting pilots using a dedicated set of resources (e.g., a radio resource control (RRC) dedicated state, etc.) or a configuration associated with transmitting pilots using a common set of resources (e.g., an RRC common state, etc.). When operating in the RRC dedicated state, the UE may select a dedicated set of resources for transmitting a pilot signal to a network. When operating in the RRC common state, the UE may select a common set of resources for transmitting a pilot signal to the network. In either case, a pilot signal transmitted by the UE may be received by one or more network access devices, such as an AN, or a DU, or portions thereof. Each receiving network access device may be configured to receive and measure pilot signals transmitted on the common set of resources, and also receive and measure pilot signals transmitted on dedicated sets of resources allocated to the UEs for which the network access device is a member of a monitoring set of network access devices for the UE. One or more of the receiving network access devices, or a CU to which receiving network access device(s) transmit the measurements of the pilot signals, may use the measurements to identify serving cells for the UEs, or to initiate a change of serving cell for one or more of the UEs.
In the context of LTE, relaying implies that a device (e.g., destination node) communicates with a network via a relay node which is wirelessly connected to a source node via LTE radio interface, Un, a modified version of evolved terrestrial radio access network (E-UTRAN) air interface Uu. The source node may also serve its own UE as usual, in addition to sharing its radio resources for relay nodes.
As mentioned previously, in relaying operations, a relay node (also referred to herein as a relay station) is a node that receives a transmission of data and/or other information from an upstream node (e.g., source node) on a link between the source node and the upstream node. After receipt of the transmission, the relay node transmits a transmission of the data and/or other information to a downstream node (e.g., a destination node) on a link between the relay node and the destination node.
FIG. 6 illustrates an example relaying operation where a TB size supported by a link between a source node and a relay node is not supported by a link between the relay node and a destination node. In the example relaying shown in FIG. 6, a relay node may communicate with a source node and a destination node in order to transmit data between the source node and the destination node. Data received from the source node may be transmitted up and down a protocol stack, at the relay node, before the relay node is able to transmit the data to the destination node. As shown in FIG. 6, the relay node receives the TB from the source node. The TB moves up the relay node's protocol stack through the PHY, MAC, RLC, and PDCP layers and back down the relay node's protocol stack through the PDCP, RCL, MAC, and PHY layers before the TB is transmitted to the destination node.
FIG. 7 illustrates example packet processing through a communication protocol stack, in accordance with certain aspects of the present disclosure. In a wireless communication network, a packet of information may flow through several sub-layers of the communication protocol stack as it travels from one node to another. As shown in FIG. 7, the 5G new radio (NR) protocol stack is illustrated with the higher layers on top, such that an internet protocol (IP) packet progresses downward through the stack. The packet enters the protocol stack through the service data adaptation protocol (SDAP) layer and travels down the protocol stack through a PDCP layer, a RLC layer, and a MAC layer. Each protocol layer may manipulate the data by adding header or subheader information (e.g., H as illustrated in FIG. 7), converting the data into different formats, and/or combining packets to form larger packets. The MAC layer generates a MAC protocol data unit (PDU) which may include multiple MAC SDUs or only one MAC SDU. Essentially, the MAC PDU becomes the PHY SDU (which may be called a TB) when transmitted to the PHY layer. When the receiving node receives the data, the data may work its way back up through a protocol stack at the receiving node. The protocol at each layer may reverse the processing that was done by the corresponding layer by the transmitting node; headers may be removed, data may be converted back to its original format, packets that were split into smaller packets may be recombined into larger messages, and so on.
Once the data has progressed through the PHY, MAC, RLC, PDCP, and SDAP layers, the IP packet may either be used or again progress downward through the protocol layers and be sent to a second receiving node. For example, where the receiving node is also a relay node, the packet may again progress downward through the protocol layers such that the TB is in a format supported by a link between the relay node and a destination node. Thus, when the packet reaches the PHY layer, it may again be sent to a destination node.
Accordingly, in some cases, it may be advantageous to directly forward a TB to a destination node, without the need for packet processing through all layers of the 5G NR protocol stack.
Certain aspects provide techniques for direct TB forwarding in relaying operations. More specifically, the present disclosure provides techniques for transmitting, from a relay node, a TB to a destination node through only a PHY layer and a hybrid automatic repeat request (HARM) portion of a MAC layer in a protocol stack of the relay node.
Example Direct Transport Block (TB) Forwarding in Relaying Operations
Certain aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for relaying operations. For example, certain aspects provide techniques and apparatus for direct transport block (TB) forwarding in relaying operations.
As mentioned above, when a link between a source node and a relay node (e.g., source-relay link) supports a TB size different than a TB size supported by a link between the source node and a destination node (e.g., relay-destination link), then a normal relaying scheme may be implemented, requiring data to be processed (i.e., transmitted up and down the 5G New Radio (NR) protocol stack at the relay node) before transmission to the destination node. However, in some cases where the source-relay link and the relay-destination link support the same TB size, in accordance with aspects of the present disclosure, the relay node may directly forward the TB, received from the source node, to the destination node. As used herein, directly forwarding the TB refers to a relay node transmitting a TB to a destination node without the TB going through the relay node's complete protocol stack. In other words, the TB may progress through less than all layers of the protocol stack at the relay node (e.g., the internet protocol (IP) packet may be processed up and down the protocol stack through less than all of the Physical (PHY), Media Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP), and service data adaption protocol (SDAP) layers) prior to the relay node transmitting the TB to the destination node. In some examples, the TB is only processed by the PHY layer at the relay node before it is transmitted to the destination node. In some examples, only the PHY layer and a hybrid automatic repeat request (HARQ) portion of the MAC layer at the relay node process the TB before it is transmitted to the destination node.
FIG. 8 illustrates an example relaying operation where a source-relay link and a relay-destination link support the same TB size, in accordance with certain aspects of the present disclosure. In the example relaying operation shown in FIG. 8, a relay node may communicate with a source node and a destination node in order to transmit data between the source node and the destination node. Data received from the source node may be forwarded directly to the destination node. As mentioned herein, direct forwarding may include transmitting a TB through less than all layers of a protocol stack of the relay node. In an aspect, as illustrated in FIG. 8, direct forwarding may include transmitting a TB to the destination node through only a PHY layer in a protocol stack of the relay node. Instead of processing the packet up and down each layer in the protocol stack (as shown in FIG. 6), the relay node may demodulate and decode the received PHY layer data channel from the source node (e.g., demodulate and decode the TB) and then encode and modulate the TB, such that it may be forwarded to the destination node. In another aspect (not illustrated), direct forwarding may include transmitting a TB to the destination node through only the PHY layer and a HARQ portion of a MAC layer in the protocol stack at the relay node. The MAC layer of the protocol stack at the relay node may be involved in the TB forwarding process because the MAC layer controls the HARQ process. For example, if a first transmission from the relay node to the destination node fails, then the MAC layer may need to perform HARQ. While the MAC layer may be involved in the direct TB forwarding, the MAC protocol data unit (PDU) may not be changed at the relay node.
To enable direct TB forwarding in relaying operations, resources may be allocated such that the source-relay link and the relay-destination link support the same TB size. Resource allocation (which may be performed by the source node) may include determining a number of identifications (IDs) to allocate for each link and determining a modulation and coding scheme (MCS) to be selected for each link based on link quality, respective to each of the source-relay link and the relay-destination link.
Additionally, the relay node may know whether it should use a normal relaying scheme or use the direct TB forwarding scheme. In some aspects, the relay node may be instructed by the source node to use direct TB forwarding (i.e., the source node may transmit, to the relay node, an indication to directly forward the TB).
FIG. 9 is a flow diagram illustrating example operations 900 for wireless communication, in accordance with certain aspects of the present disclosure. The operations 900 may be performed, for example, by a relay node (e.g., such as a UE 120 or relay station 110r in the wireless communication network 100). The operations 900 may be complementary operations by the relay node to the operations 1000 performed by the source node (e.g., such as a BS 110 in the wireless communication network 100). Operations 900 may be implemented as software components that are executed and run on one or more processors (e.g., processor 480 of FIG. 4). Further, the transmission and reception of signals by the relay node in operations 900 may be enabled, for example, by one or more antennas (e.g., antennas 452 of FIG. 4). In certain aspects, the transmission and/or reception of signals by the UE may be implemented via a bus interface of one or more processors (e.g., processor 480) obtaining and/or outputting signals.
The operations 900 may begin, at block 905, by a relay node, receiving, from a source node, an indication to directly forward a TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a PHY layer and a HARQ portion of a MAC layer in a protocol stack of the relay node. At block 910, the relay node, directly forwards the TB to the destination node based, at least in part, on the indication.
FIG. 10 is a flow diagram illustrating example operations 1000 for wireless communication, in accordance with certain aspects of the present disclosure. The operations 1000 may be performed, for example, by a source node (e.g., such as a BS 110 in the wireless communication network 100). Operations 1000 may be implemented as software components that are executed and run on one or more processors (e.g., processor 440 of FIG. 4). Further, the transmission and reception of signals by the source node in operations 1000 may be enabled, for example, by one or more antennas (e.g., antennas 434 of FIG. 4). In certain aspects, the transmission and/or reception of signals by the source node may be implemented via a bus interface of one or more processors (e.g., processor 440) obtaining and/or outputting signals.
The operations 1000 may begin, at block 1005, by the source node transmitting, to a relay node, a grant for a TB. At block 1010, the source node transmits, to the relay node, an indication to directly forward the TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a PHY layer and a HARQ portion of a MAC layer in a protocol stack of the relay node. At block 1015, the source node transmits, to the relay node, the TB in accordance with the grant.
Operations of FIGS. 9 and 10 may be understood with reference to diagram 1100 of FIG. 11 which illustrates direct TB forwarding in relaying operations. In some examples, a relay node may know to use direct TB forwarding in the relaying operation based on an indication, sent by a source node, to directly forward a TB to a destination node.
FIG. 11 is a call flow diagram illustrating example signaling for relaying operations in sidelink (SL) transmission mode 1, in accordance with aspects of the present disclosure. In NR, there are generally two basic SL resource allocation modes. According to a first mode (Mode 1), as shown in FIG. 11, a source node 1102 may allocate resources for SL communications between a relay node 1104 and a destination node 1106.
Relaying operations of FIG. 11, may begin, at 1108, by the relay node 1104 transmitting, to the source node 1102, one or more channel quality indicator (CQI) indices. In some examples, one of the CQI indices may comprise SL CQI for a link between the relay node 1104 and the destination node 1106. In some examples, one of the CQI indices may comprise a downlink (DL) CQI for a link between the relay node 1104 and the source node 1102.
At 1110, based on the received CQI indices, the source node 1102 may perform resource allocation. In some aspects, where a SL CQI is received from the relay node 1104, the source node 1102 may allocate SL resources for a SL grant (e.g., a grant for the TB includes a SL grant) based on the SL CQI. In some aspects, where a DL CQI is received from the relay node 1104, the source node 1102 may allocate DL resources for a DL grant (e.g., a grant for the TB includes a DL grant) based on the DL CQI. The source node may allocate resources for the SL grant and the DL grant such that the TB size supported by the source-relay link (e.g., DL) and the relay-destination link (e.g., SL) support the same TB size. In other words, a first TB size supported by the source-relay link and a second TB size supported by the relay-destination link may be the same.
At 1112, the source node 1102 may transmit to the relay node 1104 control information for one or more data channels for decoding the TB. The control information may configure at least one of a DL grant, a SL grant, or both. In some examples, the DL grant and the SL grant may be separate. In some examples, the DL grant and the SL grant may be joined to form one DL/SL grant.
At 1114, the source node 1102 may further transmit an indication, to the relay node 1104, to directly forward the TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a PHY layer and a HARQ portion of a MAC layer in a protocol stack of the relay node 1104. In some examples, the indication may include a 1-bit indication in either the SL grant alone or in the SL grant which is part of the joint DL/SL grant. In some examples, the indication may be sent via radio resource control (RRC) signaling. An RRC pre-configured relay node 1104 may be configured to perform direct TB forwarding in all relaying transmissions.
At 1116, the source node 1102 may transmit, to the relay node 1104, the TB in accordance with the grant. Following receipt of the control information and the TB, at 1118, the relay node 1104 may decode the TB based, at least in part, on the control information. At 1120, the relay node 1104 may determine, based on the indication, to transmit the TB through only a PHY layer and a HARQ portion of a MAC layer in the protocol stack at the relay node 1104 (as opposed to processing the packet up and down the protocol stack). Subsequently, the relay node 1104 may directly forward, at 1122, the TB to the destination node 1106.
In some aspects, the control information may include an identification (ID) indicating the destination node 1106 to which the relay node 1104 may directly forward the TB to. Accordingly, the relay node 1104 may directly forward, at 1120, the TB to the destination node 1106 which corresponds to the received ID.
In some aspects, a first TB size supported by the source-relay link may be less than a second TB size supported by the relay-destination link; however, direct TB forwarding may still be enabled in the relaying operation. Where the first TB size is less than the second TB size, the source node 1104 may add padding bits to the TB such that a size of the TB with the padding bits equals the second TB size supported by the relay-destination link. Accordingly, the relay node 1104 may directly forward the TB with the padding bits to the destination node 1106 based, at least in part, on the indication.
FIG. 12 illustrates a communications device 1200 that may include various components (e.g., corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as the operations illustrated in FIG. 9. The communications device 1200 includes a processing system 1202 coupled to a transceiver 1208. The transceiver 1208 is configured to transmit and receive signals for the communications device 1200 via an antenna 1210, such as the various signals as described herein. The processing system 1202 may be configured to perform processing functions for the communications device 1200, including processing signals received and/or to be transmitted by the communications device 1200.
The processing system 1202 includes a processor 1204 coupled to a computer-readable medium/memory 1212 via a bus 1206. In certain aspects, the computer-readable medium/memory 1212 is configured to store instructions (e.g., computer-executable code) that when executed by the processor 1204, cause the processor 1204 to perform the operations illustrated in FIG. 9, or other operations for performing the various techniques discussed herein for direct TB forwarding in relaying operations. In certain aspects, computer-readable medium/memory 1212 stores code 1214 for receiving (e.g., for receiving, from a source node, an indication to directly forward a TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a PHY layer and a HARQ portion of a MAC layer in a protocol stack of the relay node) and code 1216 for directly forwarding (e.g., directly forwarding the TB to the destination node based, at least in part, on the indication). In certain aspects, the processor 1204 has circuitry configured to implement the code stored in the computer-readable medium/memory 1212. The processor 1204 includes circuitry 1224 for receiving (e.g., for receiving, from a source node, an indication to directly forward a TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a PHY layer and a HARQ portion of a MAC layer in a protocol stack of the relay node) and circuitry 1226 for directly forwarding (e.g., directly forwarding the TB to the destination node based, at least in part, on the indication).
FIG. 13 illustrates a communications device 1300 that may include various components (e.g., corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as the operations illustrated in FIG. 10. The communications device 1300 includes a processing system 1302 coupled to a transceiver 1308. The transceiver 1308 is configured to transmit and receive signals for the communications device 1300 via an antenna 1310, such as the various signals as described herein. The processing system 1302 may be configured to perform processing functions for the communications device 1300, including processing signals received and/or to be transmitted by the communications device 1300.
The processing system 1302 includes a processor 1304 coupled to a computer-readable medium/memory 1312 via a bus 1306. In certain aspects, the computer-readable medium/memory 1312 is configured to store instructions (e.g., computer-executable code) that when executed by the processor 1304, cause the processor 1304 to perform the operations illustrated in FIG. 10, or other operations for performing the various techniques discussed herein for direct TB forwarding in relaying operations. In certain aspects, computer-readable medium/memory 1312 stores code 1314 for transmitting (e.g., for transmitting, to a relay node, a grant for a TB); code 1316 for transmitting (e.g., for transmitting, to the relay node, an indication to directly forward the TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a PHY layer and a HARQ portion of a MAC layer in a protocol stack of the relay node); and code 1318 for transmitting (e.g., for transmitting, to the relay node, the TB in accordance with the grant). In certain aspects, the processor 1304 has circuitry configured to implement the code stored in the computer-readable medium/memory 1312. The processor 1304 includes circuitry 1324 for transmitting (e.g., for transmitting, to a relay node, a grant for a TB); circuitry 1326 for transmitting (e.g., for transmitting, to the relay node, an indication to directly forward the TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a PHY layer and a HARQ portion of a MAC layer in a protocol stack of the relay node); and circuitry 1328 for transmitting (e.g., for transmitting, to the relay node, the TB in accordance with the grant).
Example Aspects
Aspect 1. An apparatus method for wireless communication by a relay node, comprising: a memory and at least one processor coupled to the memory, the memory and the at least one processor being configured to: receive, from a source node, an indication to directly forward a transport block (TB) to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a Physical (PHY) layer and a hybrid automatic repeat request (HARQ) portion of a Media Access Control (MAC) layer in a protocol stack of the relay node and directly forward the TB to the destination node based, at least in part, on the indication.
Aspect 2. The apparatus of Aspect 1, wherein the indication comprises a 1-bit indication in a sidelink (SL) grant or a SL grant part of a joint downlink (DL)/SL grant.
Aspect 3. The apparatus of Aspect 1, wherein the indication is received via radio resource control (RRC) signaling.
Aspect 4. The apparatus of any of Aspects 1-3, wherein the memory and the at least one processor are further configured to: receive, from the source node, control information for one or more data channels and decode the TB based, at least in part, on the control information.
Aspect 5. The apparatus of Aspect 4, wherein the control information configures at least one of a downlink (DL) grant, a sidelink (SL) grant, or both.
Aspect 6. The apparatus of Aspect 4 or 5, wherein the control information comprises an identification (ID) indicating the destination node to which the TB should be directly forwarded to.
Aspect 7. The apparatus of any of Aspects 1-6, wherein the memory and the at least one processor are further configured to: transmit, to the source node, one or more channel quality indicator (CQI) indices and receive a grant for the TB based, at least in part, on the one or more CQI indices.
Aspect 8. The apparatus of Aspect 7, wherein a CQI index of the one or more CQI indices comprises a sidelink (SL) CQI for a link between the relay node and the destination node and the grant for the TB includes a SL grant based, at least in part, on the CQI index.
Aspect 9. The apparatus of Aspect 7 or 8, wherein a CQI index of the one or more CQI indices comprises a downlink (DL) CQI for a link between the relay node and the source node and the grant for the TB includes a DL grant based, at least in part, on the CQI index.
Aspect 10. The apparatus of any of Aspects 1-9, wherein a link between the source node and the relay node supports a first TB size and a link between the relay node and the destination node supports a second TB size.
Aspect 11. The apparatus of Aspect 10, wherein the first TB size is equal to the second TB size.
Aspect 12. The apparatus of Aspect 10 or 11, wherein the first TB size is less than the second TB size.
Aspect 13. The apparatus of Aspect 12, wherein the memory and the at least one processor are further configured to: add padding bits to the TB such that a size of the TB with the padding bits equals the second TB size and directly forward the TB with the padding bits to the destination node based, at least in part, on the indication.
Aspect 14. An apparatus method for wireless communication by a relay node, comprising: a memory and at least one processor coupled to the memory, the memory and the at least one processor being configured to: transmit, to a relay node, a grant for a transport block (TB); transmit, to the relay node, an indication to directly forward the TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a Physical (PHY) layer and a hybrid automatic repeat request (HARM) portion of a Media Access Control (MAC) layer in a protocol stack of the relay node; and transmit, to the relay node, the TB in accordance with the grant.
Aspect 15. The apparatus of Aspect 14, wherein the indication comprises a 1-bit indication in a sidelink (SL) grant or a SL grant part of a joint downlink (DL)/SL grant.
Aspect 16. The apparatus of Aspect 15, wherein the indication is sent via radio resource control (RRC) signaling.
Aspect 17. The apparatus of any of Aspects 14-16, wherein the memory and the at least one processor are further configured to transmit, to the relay node, control information for one or more data channels for decoding the TB, wherein the relay node decodes the TB based, at least in part, on the control information.
Aspect 18. The apparatus of Aspect 17, wherein the control information configures at least one of a downlink (DL) grant, a sidelink (SL) grant, or both.
Aspect 19. The apparatus of Aspect 17 or 18, wherein the control information comprises an identification (ID) indicating the destination node to which the TB should be directly forwarded to.
Aspect 20. The apparatus of any of Aspects 14-19, wherein the memory and the at least one processor are further configured to receive, from the relay node, one or more channel quality indicator (CQI) indices, wherein the grant for the TB is based, at least in part, on the one or more CQI indices.
Aspect 21. The apparatus of Aspect 20, wherein a CQI index of the one or more CQI indices comprises a sidelink (SL) CQI for a link between the relay node and the destination node and the grant for the TB includes a SL grant based, at least in part on the CQI index.
Aspect 22. The apparatus of Aspect 20 or 21, wherein a CQI index of the one or more CQI indices comprises a downlink (DL) CQI for a link between the relay node and the source node and the grant for the TB includes a DL grant based, at least in part on the CQI index.
Aspect 23. The apparatus of any of Aspects 14-22, wherein a link between the source node and the relay node supports a first TB size and a link between the relay node and the destination node supports a second TB size.
Aspect 24. The apparatus of Aspect 23, wherein the first TB size is equal to the second TB size.
Aspect 25. A method for wireless communication by a relay node, comprising: receiving, from a source node, an indication to directly forward a transport block (TB) to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a Physical (PHY) layer and a hybrid automatic repeat request (HARQ) portion of a Media Access Control (MAC) layer in a protocol stack of the relay node and directly forwarding the TB to the destination node based, at least in part, on the indication.
Aspect 26. The method of Aspect 25, wherein the indication comprises a 1-bit indication in a sidelink (SL) grant or a SL grant part of a joint downlink (DL)/SL grant.
Aspect 27. The method of Aspect 25 or 26, further comprising: transmitting, to the source node, one or more channel quality indicator (CQI) indices and receiving a grant for the TB based, at least in part, on the one or more CQI indices.
Aspect 28. A method for wireless communication by a source node, comprising: transmitting, to a relay node, a grant for a transport block (TB); transmitting, to the relay node, an indication to directly forward the TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a Physical (PHY) layer and a hybrid automatic repeat request (HARQ) portion of a Media Access Control (MAC) layer in a protocol stack of the relay node; and transmitting, to the relay node, the TB in accordance with the grant.
Aspect 29. The method of Aspect 28, wherein the indication comprises a 1-bit indication in a sidelink (SL) grant or a SL grant part of a joint downlink (DL)/SL grant.
Aspect 30. The method of Aspect 28 or 29, further comprising receiving, from the relay node, one or more channel quality indicator (CQI) indices, wherein the grant for the TB is based, at least in part, on the one or more CQI indices.
ADDITIONAL CONSIDERATIONS
The methods disclosed herein comprise one or more steps or actions for achieving the methods. The method steps and/or actions may be interchanged with one another. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified.
As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).
As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure), ascertaining and the like. Also, “determining” may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.
The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. § 112(f) unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.”
The various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component(s) and/or module(s), including, but not limited to a circuit, an application specific integrated circuit (ASIC), or processor. Generally, where there are operations illustrated in figures, those operations may have corresponding counterpart means-plus-function components with similar numbering.
The various illustrative logical blocks, modules and circuits described in connection with the present disclosure may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
If implemented in hardware, an example hardware configuration may comprise a processing system in a wireless node. The processing system may be implemented with a bus architecture. The bus may include any number of interconnecting buses and bridges depending on the specific application of the processing system and the overall design constraints. The bus may link together various circuits including a processor, machine-readable media, and a bus interface. The bus interface may be used to connect a network adapter, among other things, to the processing system via the bus. The network adapter may be used to implement the signal processing functions of the PHY layer. In the case of a user terminal 120 (see FIG. 1), a user interface (e.g., keypad, display, mouse, joystick, etc.) may also be connected to the bus. The bus may also link various other circuits such as timing sources, peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further. The processor may be implemented with one or more general-purpose and/or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuitry that can execute software. Those skilled in the art will recognize how best to implement the described functionality for the processing system depending on the particular application and the overall design constraints imposed on the overall system.
If implemented in software, the functions may be stored or transmitted over as one or more instructions or code on a computer readable medium. Software shall be construed broadly to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Computer-readable media include both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. The processor may be responsible for managing the bus and general processing, including the execution of software modules stored on the machine-readable storage media. A computer-readable storage medium may be coupled to a processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. By way of example, the machine-readable media may include a transmission line, a carrier wave modulated by data, and/or a computer readable storage medium with instructions stored thereon separate from the wireless node, all of which may be accessed by the processor through the bus interface. Alternatively, or in addition, the machine-readable media, or any portion thereof, may be integrated into the processor, such as the case may be with cache and/or general register files. Examples of machine-readable storage media may include, by way of example, RAM (Random Access Memory), flash memory, ROM (Read Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable Programmable Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), registers, magnetic disks, optical disks, hard drives, or any other suitable storage medium, or any combination thereof. The machine-readable media may be embodied in a computer-program product.
A software module may comprise a single instruction, or many instructions, and may be distributed over several different code segments, among different programs, and across multiple storage media. The computer-readable media may comprise a number of software modules. The software modules include instructions that, when executed by an apparatus such as a processor, cause the processing system to perform various functions. The software modules may include a transmission module and a receiving module. Each software module may reside in a single storage device or be distributed across multiple storage devices. By way of example, a software module may be loaded into RAM from a hard drive when a triggering event occurs. During execution of the software module, the processor may load some of the instructions into cache to increase access speed. One or more cache lines may then be loaded into a general register file for execution by the processor. When referring to the functionality of a software module below, it will be understood that such functionality is implemented by the processor when executing instructions from that software module.
Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared (IR), radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray® disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Thus, in some aspects computer-readable media may comprise non-transitory computer-readable media (e.g., tangible media). In addition, for other aspects computer-readable media may comprise transitory computer-readable media (e.g., a signal). Combinations of the above can also be considered as computer-readable media.
Thus, certain aspects may comprise a computer program product for performing the operations presented herein. For example, such a computer program product may comprise a computer-readable medium having instructions stored (and/or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein. For example, instructions for performing the operations described herein and illustrated in FIGS. 9 and 10.
Further, it should be appreciated that modules and/or other appropriate means for performing the methods and techniques described herein can be downloaded and/or otherwise obtained by a user terminal and/or base station as applicable. For example, such a device can be coupled to a server to facilitate the transfer of means for performing the methods described herein. Alternatively, various methods described herein can be provided via storage means (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or floppy disk, etc.), such that a user terminal and/or base station can obtain the various methods upon coupling or providing the storage means to the device. Moreover, any other suitable technique for providing the methods and techniques described herein to a device can be utilized.
It is to be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus described above.

## Claims

1. An apparatus for wireless communication by a relay node, comprising:
a memory and at least one processor coupled to the memory, the memory and the at least one processor being configured to:
receive, from a source node, an indication to directly forward a transport block (TB) to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a Physical (PHY) layer and a hybrid automatic repeat request (HARD) portion of a Media Access Control (MAC) layer in a protocol stack of the relay node; and
directly forward the TB to the destination node based, at least in part, on the indication.

2. The apparatus of claim 1, wherein the indication comprises a 1-bit indication in a sidelink (SL) grant or a SL grant part of a joint downlink (DL)/SL grant.

3. The apparatus of claim 1, wherein the indication is received via radio resource control (RRC) signaling.

4. The apparatus of claim 1, wherein the memory and the at least one processor are further configured to:
receive, from the source node, control information for one or more data channels; and
decode the TB based, at least in part, on the control information.

5. The apparatus of claim 4, wherein the control information configures at least one of a downlink (DL) grant, a sidelink (SL) grant, or both.

6. The apparatus of claim 4, wherein the control information comprises an identification (ID) indicating the destination node to which the TB should be directly forwarded to.

7. The apparatus of claim 1, wherein the memory and the at least one processor are further configured to:
transmit, to the source node, one or more channel quality indicator (CQI) indices; and
receive a grant for the TB based, at least in part, on the one or more CQI indices.

8. The apparatus of claim 7, wherein:
a CQI index of the one or more CQI indices comprises a sidelink (SL) CQI for a link between the relay node and the destination node; and
the grant for the TB includes a SL grant based, at least in part, on the CQI index.

9. The apparatus of claim 7, wherein:
a CQI index of the one or more CQI indices comprises a downlink (DL) CQI for a link between the relay node and the source node; and
the grant for the TB includes a DL grant based, at least in part, on the CQI index.

10. The apparatus of claim 1, wherein:
a link between the source node and the relay node supports a first TB size; and
a link between the relay node and the destination node supports a second TB size.

11. The apparatus of claim 10, wherein the first TB size is equal to the second TB size.

12. The apparatus of claim 10, wherein the first TB size is less than the second TB size.

13. The apparatus of claim 12, wherein the memory and the at least one processor are further configured to:
add padding bits to the TB such that a size of the TB with the padding bits equals the second TB size; and
directly forward the TB with the padding bits to the destination node based, at least in part, on the indication.

14. An apparatus for wireless communication by a source node, comprising:
a memory and at least one processor coupled to the memory, the memory and the at least one processor being configured to:
transmit, to a relay node, a grant for a transport block (TB);
transmit, to the relay node, an indication to directly forward the TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a Physical (PHY) layer and a hybrid automatic repeat request (HARD) portion of a Media Access Control (MAC) layer in a protocol stack of the relay node; and
transmit, to the relay node, the TB in accordance with the grant.

15. The apparatus of claim 14, wherein the indication comprises a 1-bit indication in a sidelink (SL) grant or a SL grant part of a joint downlink (DL)/SL grant.

16. The apparatus of claim 14, wherein the indication is sent via radio resource control (RRC) signaling.

17. The apparatus of claim 14, wherein the memory and the at least one processor are further configured to transmit, to the relay node, control information for one or more data channels for decoding the TB, wherein the relay node decodes the TB based, at least in part, on the control information.

18. The apparatus of claim 17, wherein the control information configures at least one of a downlink (DL) grant, a sidelink (SL) grant, or both.

19. The apparatus of claim 17, wherein the control information comprises an identification (ID) indicating the destination node to which the TB should be directly forwarded to.

20. The apparatus of claim 14, wherein the memory and the at least one processor are further configured to receive, from the relay node, one or more channel quality indicator (CQI) indices, wherein the grant for the TB is based, at least in part, on the one or more CQI indices.

21. The apparatus of claim 20, wherein:
a CQI index of the one or more CQI indices comprises a sidelink (SL) CQI for a link between the relay node and the destination node; and
the grant for the TB includes a SL grant based, at least in part on the CQI index.

22. The apparatus of claim 20, wherein:
a CQI index of the one or more CQI indices comprises a downlink (DL) CQI for a link between the relay node and the source node; and
the grant for the TB includes a DL grant based, at least in part on the CQI index.

23. The apparatus of claim 14, wherein:
a link between the source node and the relay node supports a first TB size; and
a link between the relay node and the destination node supports a second TB size.

24. The apparatus of claim 23, wherein the first TB size is equal to the second TB size.

25. A method for wireless communication by a relay node, comprising:
receiving, from a source node, an indication to directly forward a transport block (TB) to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a Physical (PHY) layer and a hybrid automatic repeat request (HARQ) portion of a Media Access Control (MAC) layer in a protocol stack of the relay node; and
directly forwarding the TB to the destination node based, at least in part, on the indication.

26. The method of claim 25, wherein the indication comprises a 1-bit indication in a sidelink (SL) grant or a SL grant part of a joint downlink (DL)/SL grant.

27. The method of claim 25, further comprising:
transmitting, to the source node, one or more channel quality indicator (CQI) indices; and
receiving a grant for the TB based, at least in part, on the one or more CQI indices.

28. A method for wireless communication by a source node, comprising:
transmitting, to a relay node, a grant for a transport block (TB);
transmitting, to the relay node, an indication to directly forward the TB to a destination node, wherein directly forwarding includes transmitting the TB to the destination node through only a Physical (PHY) layer and a hybrid automatic repeat request (HARQ) portion of a Media Access Control (MAC) layer in a protocol stack of the relay node; and
transmitting, to the relay node, the TB in accordance with the grant.

29. The method of claim 28, wherein the indication comprises a 1-bit indication in a sidelink (SL) grant or a SL grant part of a joint downlink (DL)/SL grant.

30. The method of claim 28, further comprising receiving, from the relay node, one or more channel quality indicator (CQI) indices, wherein the grant for the TB is based, at least in part, on the one or more CQI indices.