Patent Publication Number: US-2022225313-A1

Title: Method of using a 2-stage sidelink control information (sci) design

Description:
CLAIM OF PRIORITY 
     The present application claims priority to Provisional Application No. 62/857,151, entitled “METHOD TO USE THE 2-STAGE SIDELINK CONTROL INFORMATION (SCI) DESIGN TO SUPPORT THE FORWARDING AND THE UE-RELAY FEATURES”, filed Jun. 4, 2019, which is assigned to the assignee hereof and hereby expressly incorporated by reference in its entirety. 
    
    
     FIELD 
     This invention generally relates to wireless communications and more particularly to vehicle-to-everything (V2X) communications between wireless communication devices. 
     BACKGROUND 
     In a network of wireless communication devices, there are times when it may be advantageous to forward signals. 
     SUMMARY 
     The methods, devices, and systems discussed herein utilize a 2-stage Sidelink Control Information (SCI) design when a forwarding user equipment device (UE) forwards the time-frequency location of communication resources that (1) have been reserved by another UE, or (2) are available for a receiving UE to use for device-to-device (D2D) data transmissions. In some examples, the 1 st  and 2 nd  stages of the SCI are required to decode the data channel. In these examples, part of the SCI is in the 1 st  stage, and the remaining part is in the 2 nd  stage. Thus, a UE that receives the 2-stage SCI decodes the 1 st  stage for sensing whether the associated data channel is being used. The 2 nd  stage has the remaining relevant SCI required to demodulate and decode the same associated data channel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a block diagram of an example of a system in which a transmitting user equipment device (UE) transmits a signal, which identifies a time-frequency location of communication resources, to a forwarding UE. The forwarding UE transmits, to a receiving UE, a forwarded signal that includes Sidelink Control Information (SCI) having a 1 st  stage and a 2 nd  stage, the 2 nd  stage including the time-frequency location of communication resources that was identified in the signal received at the forwarding UE. 
         FIG. 1B  is a block diagram of an example of the system of  FIG. 1A  in which the forwarding UE receives the signal that identifies the time-frequency location of communication resources from a base station. 
         FIG. 2  is a block diagram of an example of the forwarding UE shown in  FIG. 1A . 
         FIG. 3  is a block diagram of an example of the base station shown in  FIG. 1B . 
         FIG. 4  is a diagram of an example showing the relative time-slots in which the signal  104  and the forwarded signal  108  are transmitted in  FIG. 1A . 
         FIG. 5  is a flowchart of an example of a method of forwarding a signal that includes Sidelink Control Information (SCI) having a 1 st  stage and a 2 nd  stage. The 2 nd  stage includes a time-frequency location of communication resources that was identified in a signal received at the forwarding UE. 
     
    
    
     DETAILED DESCRIPTION 
     The examples discussed below are generally directed to vehicle-to-everything (V2X) communication, which is the passing of information from a vehicle to any entity that may affect the vehicle or that the vehicle may affect. For example, V2X is a vehicular communication system that incorporates other, more specific types of communication, including vehicle-to-vehicle (V2V), V2I (vehicle-to-infrastructure), V2N (vehicle-to-network), V2P (vehicle-to-pedestrian), V2D (vehicle-to-device), and V2G (vehicle-to-grid). There are two types of V2X communication technology depending on the underlying technology being used: wireless local area network (WLAN)-based V2X, and cellular-based V2X (C-V2X). Some examples of V2X protocols include Long-Term Evolution (LTE) (Rel-14) V2X Mode 4 and 5G New Radio (NR) V2X Mode 2. 
     Sidelink transmissions are supported for V2X over the sidelink (SL) channel or the PC5 interface, which is an interface used for direct communication between a user equipment device (UE) and another UE. Sidelink Control Information (SCI) is control information that is transmitted over the SL channel. In the examples described herein, a forwarding UE transmits forwarded signals that contain a 2-stage SCI. 
     In some examples, the 1 st  and 2 nd  stages of the SCI are required to decode the data channel. In these examples, part of the SCI is in the 1 st  stage, and the remaining part is in the 2 nd  stage. Thus, a UE that receives the 2-stage SCI decodes the 1 st  stage for sensing whether the associated data channel is being used. The 2 nd  stage has the remaining relevant SCI required to demodulate and decode the same associated data channel. In some examples, the 1 st  stage is transmitted within a Physical Sidelink Control Channel (PSCCH). In some examples, the 2 nd  stage is transmitted within a Physical Sidelink Shared Channel (PSSCH). 
     The methods, devices, and systems discussed herein utilize the 2-stage SCI design when forwarding the time-frequency location of communication resources that (1) have been reserved, or (2) are available for the receiving UE to use for device-to-device (D2D) data transmissions. Although the different examples described herein may be discussed separately, any of the features of any of the examples may be added to, omitted from, or combined with any other example. Similarly, any of the features of any of the examples may be performed in parallel or performed in a different manner/order than that described or shown herein. 
       FIG. 1A  is a block diagram of an example of a system in which a transmitting user equipment device (UE) transmits a signal, which identifies a time-frequency location of communication resources, to a forwarding UE. The forwarding UE transmits, to a receiving UE, a forwarded signal that includes Sidelink Control Information (SCI) having a 1 st  stage and a 2 nd  stage. The 2 nd  stage includes the time-frequency location of communication resources that was identified in the signal received at the forwarding UE. 
     For the example of  FIG. 1A , a group of UEs is located on roadway  100 . The group includes a transmitting UE, TX UE,  106 , a forwarding UE, FWD UE,  102 , and a receiving UE, RX UE,  110 . In other examples, the group may have a different number of UEs than that shown in  FIG. 1A . For example, multiple UEs may act as transmitting UEs, forwarding UEs, and/or receiving UEs. In still further examples, each of the UEs within the group of UEs may be a node of a vehicle ad-hoc network (VANET). 
     The group of UEs is wirelessly connected to a radio access network (not shown) via one or more base stations (not shown in  FIG. 1A ), which provide various wireless services to one or more of the UEs that are part of the group of UEs. For the example shown in  FIG. 1A , the group of UEs operates in accordance with at least one revision of the 3rd Generation Partnership Project 5G New Radio (3GPP 5G NR) communication specification. In other examples, the group of UEs may operate in accordance with other communication specifications. 
     In the example of  FIG. 1A , UEs  102 ,  106 ,  110  are each integrated into a vehicle as an onboard unit (OBU). In other examples, UEs  102 ,  106 ,  110  may simply be user equipment (UE) devices that are located within a vehicle. Some examples of user equipment devices include: a mobile phone, a transceiver modem, a personal digital assistant (PDA), or a tablet, for example. Any of the foregoing devices may also be referenced herein as vehicle UEs (VUEs). Each of the UEs  102 ,  106 ,  110  that are connected to the group of UEs is considered to be a member of the group. 
     As shown in  FIG. 2 , UE  102  comprises controller  206 , transmitter  208 , and receiver  204 , as well as other electronics, hardware, and code. Although  FIG. 2  specifically depicts the circuitry and configuration of UE  102 , the same user equipment device circuitry and configuration is utilized for UEs  106 ,  110 . In other examples, any of the UEs may have circuitry and/or a configuration that differs from that of UE  102  shown in  FIG. 2 . 
     UE  102  is any fixed, mobile, or portable equipment that performs the functions described herein. The various functions and operations of the blocks described with reference to UE  102  may be implemented in any number of devices, circuits, or elements. Two or more of the functional blocks may be integrated in a single device, and the functions described as performed in any single device may be implemented over several devices. 
     Controller  206  includes any combination of hardware, software, and/or firmware for executing the functions described herein as well as facilitating the overall functionality of a user equipment device. An example of a suitable controller  206  includes code running on a microprocessor or processor arrangement connected to memory. Transmitter  208  includes electronics configured to transmit wireless signals. In some situations, the transmitter  208  may include multiple transmitters. Receiver  204  includes electronics configured to receive wireless signals. In some situations, receiver  204  may include multiple receivers. Receiver  204  and transmitter  208  receive and transmit signals, respectively, through antenna  202 . Antenna  202  may include separate transmit and receive antennas. In some circumstances, antenna  202  may include multiple transmit and receive antennas. 
     Transmitter  208  and receiver  204  in the example of  FIG. 2  perform radio frequency (RF) processing including modulation and demodulation. Receiver  204 , therefore, may include components such as low noise amplifiers (LNAs) and filters. Transmitter  208  may include filters and amplifiers. Other components may include isolators, matching circuits, and other RF components. These components in combination or cooperation with other components perform the user equipment device functions. The required components may depend on the particular functionality required by the user equipment device. 
     Transmitter  208  includes a modulator (not shown), and receiver  204  includes a demodulator (not shown). The modulator can apply any one of a plurality of modulation orders to modulate the signals to be transmitted over the sidelink channel. The demodulator demodulates signals received over the sidelink channel, in accordance with one of a plurality of modulation orders. 
     In operation, a wireless communication device (e.g., equipment) transmits, to a forwarding UE, a signal that identifies a time-frequency location of communication resources. In the example of  FIG. 1A , the wireless communication device is transmitting UE  106 . In the example of  FIG. 1B , the wireless communication device is base station  120 . 
     In the example of  FIG. 1A , transmitting UE  106  transmits, via its transmitter  208  and antenna  202 , a signal  104  that identifies a time-frequency location of communication resources. In some examples, the identified time-frequency location of communication resources is a time-frequency location of communication resources reserved by transmitting UE  106 . In other examples, the identified time-frequency location of communication resources is a time-frequency location of communication resources that are available for receiving UE  110  to use for device-to-device (D2D) data transmissions. 
     Forwarding UE  102  receives, via its antenna  202  and receiver  204 , signal  104 . Upon receipt of signal  104 , forwarding UE  102  determines, using its controller  206 , whether to transmit a forwarded signal  108 . One possible factor in determining whether to transmit a forwarded signal  108  is whether the forwarded signal  108  would be beneficial to other UEs that are not yet in range of transmitting UE  106 . 
     In the example shown in  FIG. 1A , transmitting UE  106  has coverage area  114 , forwarding UE  102  has coverage area  112 , and receiving UE  110  has coverage area  116 . As shown in  FIG. 1A , forwarding UE  102  is within the range (e.g., coverage area  114 ) of transmitting UE  106 , but receiving UE  110  is not. Thus, transmitting UE  106  and receiving UE  110  may not be able to reliably communicate with one another. Accordingly, if one or more network-configured criteria are met, forwarding UE  102  will transmit a forwarded signal  108 , which is based on signal  104 , to receiving UE  110 . 
     In some examples, the determination of whether to transmit the forwarded signal  108  is based, at least partially, on whether a measured received power value of signal  104  is within a threshold range. In some examples, the threshold range corresponds with a distance at which the forwarding UE  102  is located from the wireless communication device (e.g., transmitting UE  106 ) when packet-collisions are a predominant cause for incorrect Transport Block (TB) reception. For example, under Long-Term Evolution-Vehicle (LTE-V) Release 14 Loss of Signal conditions, packet-collisions are the predominant cause for incorrect TB reception when the distance between the transmitter (e.g., transmitting UE  106 ) and the receiver (e.g., forwarding UE  102 ) is up to 250 m. When the distance between the transmitter (e.g., transmitting UE  106 ) and the receiver (e.g., forwarding UE  102 ) is larger than 250 m, propagation loss becomes the main cause of incorrect TB reception. 
     If forwarding UE  102  determines that it should transmit a forwarded signal, forwarding UE  102  uses its controller  206  to generate forwarded signal  108 . Forwarding UE  102  transmits, via its transmitter  208  and antenna  202 , forwarded signal  108  to receiving UE  110 . Forwarded signal  108  includes Sidelink Control Information (SCI) having a 1 st  stage and a 2 nd  stage. The 2 nd  stage includes the time-frequency location of communication resources that was identified in signal  104 . 
     In some examples, the 1 st  stage is transmitted within a Physical Sidelink Control Channel (PSCCH). In examples in which the time-frequency location of communication resources identified in signal  104  is a time-frequency location of communication resources reserved by the transmitting UE  106 , the 1 st  stage of the SCI includes an indication that forwarded signal  108  contains forwarded resource reservation information. For example, an indicator can be set in a 1-bit “forwarding” field or some other field of the 1 st  stage of the SCI to explicitly or implicitly indicate that the time-frequency location of communication resources included in forwarded signal  108  signifies a forwarded reservation of communication resources, respectively. In this manner, a receiving UE  110  that is interested in receiving information regarding communication resources that have been reserved by other nodes (e.g., UEs) that are not in range (e.g., hidden nodes) can be made aware of the reserved communication resources when it decodes the 2 nd  stage of the SCI to get information on the reserved communication resources. Of course, the “forwarding” field can have more than 1 bit, in other examples. 
     In some examples, the 1 st  stage of the SCI includes an indication that the 2 nd  stage contains additional control information. For example, an indicator can be set in a 6-bit “2 nd  Stage SCI” field of the 1 st  stage of the SCI to indicate that the 2 nd  stage contains a future release feature. In this manner, a receiving UE  110  that is interested in receiving future release features can be made aware of the presence of a future release feature in the SCI and can decode the 2 nd  stage of the SCI to get information on the future release feature. Of course, the “2 nd  Stage SCI” field can have any suitable number of bits, in other examples. 
     As described above, the 2 nd  stage of the SCI contains the time-frequency location of communication resources that was identified in signal  104 . The 2 nd  stage of the SCI also contains the control information that an intended receiving UE needs to demodomulate and decode the associated data channel. In some examples, the 2 nd  stage is transmitted within a Physical Sidelink Shared Channel (PSSCH). 
     In some examples in which the time-frequency location of communication resources identified in signal  104  is a time-frequency location of communication resources reserved by the transmitting UE  106 , the 2 nd  stage of the SCI includes a 9-bit “Forwarded Reserve Resource Location” field that provides the time-frequency location of the communication resources reserved by transmitting UE  106 . In some examples in which the identified time-frequency location of communication resources is a time-frequency location of communication resources that are available for a receiving UE  110  to use for device-to-device (D2D) data transmissions, the 2 nd  stage of the SCI includes a “Resource Pool Information” field that provides information regarding the communication resources that can be used by receiving UE  110  for device-to-device (D2D) data transmissions. 
     In some examples, the 2 nd  stage of the SCI includes a serving cell identifier (ID) associated with a serving cell of transmitting UE  106 . For example, an identifier can be set in a “Transmitter UE Serving Cell ID” field of the 2 nd  stage of the SCI. This information is useful if a receiving UE  110  receives forwarded information from multiple forwarding UEs that are served by different cells. 
     In other examples, the 2 nd  stage of the SCI includes Multimedia Broadcast Multicast Service (MBMS) information. For example, an “MBMS Services Information” field of the 2 nd  stage of the SCI can be used to forward MBMS services (e.g, Temporary Mobile Group Identities) or group communication services (e.g., Group-Radio Network Temporary Identifiers) that are being broadcasted or multicasted from the serving cell of transmitting UE  106 . 
     Regardless of the contents of forwarded signal  108 , receiving UE  110  receives, via its antenna  202  and receiver  204 , forwarded signal  108 . Receiving UE  110  uses its controller  206  to decode forwarded signal  108 , including the 2-stage SCI. 
       FIG. 1B  is a block diagram of an alternative example of the system of  FIG. 1A  in which a forwarding UE receives a signal, which identifies the time-frequency location of communication resources, from a base station instead of from a transmitting UE. More specifically, forwarding UE  102  receives, via its antenna  202  and receiver  204 , signal  104  from base station  120 . 
     In the interest of clarity and brevity, only one infrastructure communication node (e.g., base station  120 ) is shown in  FIG. 1B . However, in other examples, any suitable number of infrastructure communication nodes may be utilized to obtain/maintain communication with the network. For the example shown in  FIG. 1B , base station  120 , sometimes referred to as eNodeB or eNB, transmits signal  104  to forwarding UE  102 . In other examples, the infrastructure communication node is a road side unit (RSU). 
     For the example shown in  FIG. 1B , signal  104  is shown as a broadcast downlink signal from base station  120  to forwarding UE  102 . Forwarding UE  102  is also capable of transmitting uplink signals (not shown) to base station  120 . Base station  120  is connected to the network through a backhaul (not shown) in accordance with known techniques. 
     As shown in  FIG. 3 , base station  120  comprises controller  302 , transmitter  304 , and receiver  306 , as well as other electronics, hardware, and code. Base station  120  is any fixed, mobile, or portable equipment that performs the functions described herein. The various functions and operations of the blocks described with reference to base station  120  may be implemented in any number of devices, circuits, or elements. Two or more of the functional blocks may be integrated in a single device, and the functions described as performed in any single device may be implemented over several devices. 
     For the example shown in  FIG. 3 , base station  120  may be a fixed device or apparatus that is installed at a particular location at the time of system deployment. Examples of such equipment include fixed base stations or fixed transceiver stations. In some situations, base station  120  may be mobile equipment that is temporarily installed at a particular location. Some examples of such equipment include mobile transceiver stations that may include power generating equipment such as electric generators, solar panels, and/or batteries. Larger and heavier versions of such equipment may be transported by trailer. In still other situations, base station  120  may be a portable device that is not fixed to any particular location. Accordingly, base station  120  may be a portable user device such as a UE device in some circumstances. 
     Controller  302  includes any combination of hardware, software, and/or firmware for executing the functions described herein as well as facilitating the overall functionality of base station  120 . An example of a suitable controller  302  includes code running on a microprocessor or processor arrangement connected to memory. Transmitter  304  includes electronics configured to transmit wireless signals. In some situations, transmitter  304  may include multiple transmitters. Receiver  306  includes electronics configured to receive wireless signals. In some situations, receiver  306  may include multiple receivers. Receiver  306  and transmitter  304  receive and transmit signals, respectively, through antenna  308 . Antenna  308  may include separate transmit and receive antennas. In some circumstances, antenna  308  may include multiple transmit and receive antennas. 
     Transmitter  304  and receiver  306  in the example of  FIG. 3  perform radio frequency (RF) processing including modulation and demodulation. Receiver  306 , therefore, may include components such as low noise amplifiers (LNAs) and filters. Transmitter  304  may include filters and amplifiers. Other components may include isolators, matching circuits, and other RF components. These components in combination or cooperation with other components perform the base station functions. The required components may depend on the particular functionality required by the base station. 
     Transmitter  304  includes a modulator (not shown), and receiver  306  includes a demodulator (not shown). The modulator modulates the signals to be transmitted as part of a downlink signal and can apply any one of a plurality of modulation orders. The demodulator demodulates any uplink signals received at base station  120  in accordance with one of a plurality of modulation orders. 
     As mentioned above, base station  120  provides various wireless services and network connectivity to wireless communication devices (e.g., user equipment devices) within the coverage area of base station  120 . Base station  120  provides these services and connectivity by transmitting downlink signal  104 , via transmitter  304  and antenna  308 , to UE  102 . In the example of  FIG. 1B , the downlink signal  104  is transmitted in a broadcast System Information Block (SIB) message. Although not explicitly shown in  FIG. 1B , base station  120  is capable of receiving uplink signals, via antenna  308  and receiver  306 , from wireless communication devices (e.g., user equipment devices) within the coverage area of base station  120 . 
       FIG. 4  is a diagram of an example showing the relative time-slots in which the signal  104  and the forwarded signal  108  are transmitted in  FIG. 1A . More specifically,  FIG. 4  shows how transmitting UE  106  transmits signal  104  on Sub-Channel B of the PSSCH in Slot n to reserve a resource in Slot n+m. Upon receipt of signal  104  and determining that a forwarded signal should be sent, forwarding UE  102  must send the forwarded signal  108  before its usefulness expires. Thus, after receiving signal  104  in Slot n, forwarding UE  102  must transmit the forwarded signal  108  within a time duration that begins with Slot n+1 and ends with Slot n+m−1 since the reservation is for resources in Slot n+m. 
     In the example shown in  FIG. 4 , forwarding UE  102  transmits forwarded signal  108  on Sub-Channel C of the PSSCH in Slot n+2. As described above, the 1 st  stage of the SCI of forwarded signal  108  is transmitted within a Physical Sidelink Control Channel (PSCCH) and contains a 1-bit indicator in a “forwarding” field to indicate that the time-frequency location of communication resources included in forwarded signal  108  signifies a forwarded reservation of communication resources. The 2 nd  stage of the SCI of forwarded signal  108  is transmitted within a Physical Sidelink Shared Channel (PSSCH) and contains a 9-bit “Forwarded Reserve Resource Location” field that provides the time-frequency location of the communication resources (e.g., Sub-Channel A of the PSSCH in Slot n+m) that are reserved for transmitting UE  106 . 
       FIG. 5  is a flowchart of an example of a method of forwarding a signal that includes Sidelink Control Information (SCI) having a 1 st  stage and a 2 nd  stage. The 2 nd  stage includes a time-frequency location of communication resources that was identified in a signal received at the forwarding UE. The method  500  begins at step  502  with receiving, from a wireless communication device at forwarding UE  102 , a signal  104  that identifies a time-frequency location of communication resources. At step  504 , forwarding UE  102  determines to transmit forwarded signal  108  based at least partially on whether a measured received power value of signal  104  is within a threshold range. At step  506 , forwarding UE  102  transmits, to receiving UE  110 , forwarded signal  108  that includes SCI having a 1 st  stage and a 2 nd  stage. The 2 nd  stage includes the time-frequency location of communication resources that was identified in signal  104 . In other examples, one or more of the steps of method  500  may be omitted, combined, performed in parallel, or performed in a different order than that described herein or shown in  FIG. 5 . In still further examples, additional steps may be added to method  500  that are not explicitly described in connection with the example shown in  FIG. 5 . 
     Clearly, other embodiments and modifications of this invention will occur readily to those of ordinary skill in the art in view of these teachings. The above description is illustrative and not restrictive. This invention is to be limited only by the following claims, which include all such embodiments and modifications when viewed in conjunction with the above specification and accompanying drawings. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents.