Patent Publication Number: US-2022232416-A1

Title: Active congestion control for power saving ue in sidelink

Description:
BACKGROUND 
     Technical Field 
     The present disclosure relates generally to communication systems, and more particularly, to sidelink communications. 
     Introduction 
     Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple-access technologies include 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. 
     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. An example telecommunication standard is 5G New Radio (NR). 5G NR is part of a continuous mobile broadband evolution promulgated by Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with Internet of Things (IoT)), and other requirements. 5G NR includes services associated with enhanced mobile broadband (eMBB), massive machine type communications (mMTC), and ultra reliable low latency communications (URLLC). Some aspects of 5G NR may be based on the 4G Long Term Evolution (LTE) standard. Aspects of wireless communication may comprise direct communication between devices, such as in V2X and/or other D2D communication. There exists a need for further improvements in V2X and/or other D2D technology. These improvements may also be applicable to other multi-access technologies and the telecommunication standards that employ these technologies. 
     SUMMARY 
     The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later. 
     In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus of a user equipment (UE) are provided. The UE may determine a configuration of a set of congestion control measurement resources comprising one or more receiving resources and one or more transmitting resources for transmission of an activity indication signal for sidelink communication. The UE may measure received signal strength indicator (RSSI) on at least one of the one or more receiving resources. 
     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 annexed 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, and this description is intended to include all such aspects and their equivalents. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram illustrating an example of a wireless communications system and an access network. 
         FIG. 2  illustrates example aspects of a sidelink slot structure. 
         FIG. 3  is a diagram illustrating an example of a base station and user equipment (UE) in an access network. 
         FIG. 4  illustrates an example sidelink communication. 
         FIGS. 5A and 5B  illustrate example power saving mechanisms for a UE. 
         FIGS. 6A and 6B  illustrate example bandwidth adaptation mechanisms for a UE. 
         FIG. 7  illustrates an example of a congestion control mechanism. 
         FIG. 8  illustrates an example set of congestion control measurement resources. 
         FIG. 9  illustrates an example of mapping between congestion control measurement resources and transmissions. 
         FIG. 10  illustrates an example set of congestion control measurement resources. 
         FIG. 11  is a flowchart of a method of wireless communication. 
         FIG. 12  is a diagram illustrating an example of a hardware implementation for an example apparatus. 
     
    
    
     DETAILED DESCRIPTION 
     The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts. 
     Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as “elements”). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. 
     By way of example, an element, or any portion of an element, or any combination of elements may be implemented as a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, systems on a chip (SoC), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. 
     Accordingly, in one or more examples, the functions described may be implemented in hardware, software, or any combination thereof. If implemented in software, the functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer-readable media includes computer storage media. Storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise a random-access memory (RAM), a read-only memory (ROM), an electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of the aforementioned types of computer-readable media, or any other medium that can be used to store computer executable code in the form of instructions or data structures that can be accessed by a computer. 
       FIG. 1  is a diagram illustrating an example of a wireless communications system and an access network  100 . The wireless communications system (also referred to as a wireless wide area network (WWAN)) includes base stations  102 , UEs  104 , an Evolved Packet Core (EPC)  160 , and another core network  190  (e.g., a 5G Core (5GC)). The base stations  102  may include macrocells (high power cellular base station) and/or small cells (low power cellular base station). The macrocells include base stations. The small cells include femtocells, picocells, and microcells. 
     A link between a UE  104  and a base station  102  or  180  may be established as an access link, e.g., using a Uu interface. Other communication may be exchanged between wireless devices based on sidelink. For example, some UEs  104  may communicate with each other directly using a device-to-device (D2D) communication link  158 . In some examples, the D2D communication link  158  may use the DL/UL WWAN spectrum. The D2D communication link  158  may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). D2D communication may be through a variety of wireless D2D communications systems, such as for example, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, LTE, or NR. 
     Some wireless communication networks may include vehicle-based communication devices that can communicate from vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I) (e.g., from the vehicle-based communication device to road infrastructure nodes such as a Road Side Unit (RSU)), vehicle-to-network (V2N) (e.g., from the vehicle-based communication device to one or more network nodes, such as a base station), vehicle-to-pedestrian (V2P), cellular vehicle-to-everything (C-V2X), and/or a combination thereof and/or with other devices, which can be collectively referred to as vehicle-to-anything (V2X) communications. Referring again to  FIG. 1 , in certain aspects, a UE  104 , e.g., a transmitting Vehicle User Equipment (VUE) or other UE, may be configured to transmit messages directly to another UE  104 . The communication may be based on V2X or other D2D communication, such as Proximity Services (ProSe), etc. Communication based on V2X and/or other D2D communication may also be transmitted and received by other transmitting and receiving devices, such as Road Side Unit (RSU)  107 , etc. Aspects of the communication may be based on PC5 or sidelink communication e.g., as described in connection with the example in  FIG. 2 . Although the following description may provide examples for V2X or other D2D communication in connection with 5G NR, the concepts described herein may be applicable to other similar areas, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies. 
     A power-saving UE with power-saving techniques, such as discontinuous reception (DRX), wake-up signal (WUS) indication, bandwidth (BW) adaptation via bandwidth part (BWP) switch or resource pool activation/deactivation, Scell activation/deactivation, or the like, may not be continuously on to compute channel busy ratio (CBR). Aspects that enable UEs to detect activities and measure CBR using a set of congestion control measurement resources are provided herein. For example, a UE  104 , Road Side Unit (RSU)  107 , or other sidelink devices may include an activity indication component  198  configured to determine a configuration of a set of congestion control measurement resources comprising one or more receiving resources and one or more transmitting resources for transmission of an activity indication signal for sidelink communication. The activity indication component  198  may be further configured to measure RSSI on at least one of the one or more receiving resources. 
     The wireless communications system (also referred to as a wireless wide area network (WWAN)) includes base stations  102 , UEs  104 , an Evolved Packet Core (EPC)  160 , and a Core Network (e.g., 5GC)  190 . The base stations  102  may include macro cells (high power cellular base station) and/or small cells (low power cellular base station). The macro cells include base stations. The small cells include femtocells, picocells, and microcells. 
     The base stations  102  configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with the EPC  160  through backhaul links  132  (e.g., S1 interface). The base stations  102  configured for NR (collectively referred to as Next Generation RAN (NG-RAN)) may interface with Core Network  190  through backhaul links  184 . In addition to other functions, the base stations  102  may perform one or more of the following functions: transfer of user data, radio channel ciphering and deciphering, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection setup and release, load balancing, distribution for non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment trace, RAN information management (RIM), paging, positioning, and delivery of warning messages. The base stations  102  may communicate directly or indirectly (e.g., through the EPC  160  or Core Network  190 ) with each other over backhaul links  134  (e.g., X2 interface). The backhaul links  134  may be wired or wireless. 
     The base stations  102  may wirelessly communicate with the UEs  104 . Each of the base stations  102  may provide communication coverage for a respective geographic coverage area  110 . There may be overlapping geographic coverage areas  110 . For example, the small cell  102 ′ may have a coverage area  110 ′ that overlaps the coverage area  110  of one or more macro base stations  102 . A network that includes both small cell and macro cells may be known as a heterogeneous network. A heterogeneous network may also include Home Evolved Node Bs (eNBs) (HeNBs), which may provide service to a restricted group known as a closed subscriber group (CSG). The communication links  120  between the base stations  102  and the UEs  104  may include uplink (UL) (also referred to as reverse link) transmissions from a UE  104  to a base station  102  and/or downlink (DL) (also referred to as forward link) transmissions from a base station  102  to a UE  104 . The communication links  120  may use multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity. The communication links may be through one or more carriers. The base stations  102 /UEs  104  may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz) bandwidth per carrier allocated in a carrier aggregation of up to a total of Yx MHz (x component carriers) used for transmission in each direction. The carriers may or may not be adjacent to each other. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or less carriers may be allocated for DL than for UL). The component carriers may include a primary component carrier and one or more secondary component carriers. A primary component carrier may be referred to as a primary cell (PCell) and a secondary component carrier may be referred to as a secondary cell (SCell). 
     Certain UEs  104  may communicate with each other using device-to-device (D2D) communication link  158 . The D2D communication link  158  may use the DL/UL WWAN spectrum. The D2D communication link  158  may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). D2D communication may be through a variety of wireless D2D communications systems, such as for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR. 
     The wireless communications system may further include a Wi-Fi access point (AP)  150  in communication with Wi-Fi stations (STAs)  152  via communication links  154  in a 5 GHz unlicensed frequency spectrum. When communicating in an unlicensed frequency spectrum, the STAs  152 /AP  150  may perform a clear channel assessment (CCA) prior to communicating in order to determine whether the channel is available. 
     The small cell  102 ′ may operate in a licensed and/or an unlicensed frequency spectrum. When operating in an unlicensed frequency spectrum, the small cell  102 ′ may employ NR and use the same 5 GHz unlicensed frequency spectrum as used by the Wi-Fi AP  150 . The small cell  102 ′, employing NR in an unlicensed frequency spectrum, may boost coverage to and/or increase capacity of the access network. 
     The electromagnetic spectrum is often subdivided, based on frequency/wavelength, into various classes, bands, channels, etc. In 5G NR, two initial operating bands have been identified as frequency range designations FR1 (410 MHz-7.125 GHz) and FR2 (24.25 GHz-52.6 GHz). The frequencies between FR1 and FR2 are often referred to as mid-band frequencies. Although a portion of FR1 is greater than 6 GHz, FR1 is often referred to (interchangeably) as a “sub-6 GHz” band in various documents and articles. A similar nomenclature issue sometimes occurs with regard to FR2, which is often referred to (interchangeably) as a “millimeter wave” band in documents and articles, despite being different from the extremely high frequency (EHF) band (30 GHz-300 GHz) which is identified by the International Telecommunications Union (ITU) as a “millimeter wave” band. 
     With the above aspects in mind, unless specifically stated otherwise, it should be understood that the term “sub-6 GHz” or the like if used herein may broadly represent frequencies that may be less than 6 GHz, may be within FR1, or may include mid-band frequencies. Further, unless specifically stated otherwise, it should be understood that the term “millimeter wave” or the like if used herein may broadly represent frequencies that may include mid-band frequencies, may be within FR2, or may be within the EHF band. 
     A base station  102 , whether a small cell  102 ′ or a large cell (e.g., macro base station), may include and/or be referred to as an eNB, gNodeB (gNB), or another type of base station. Some base stations, such as gNB  180  may operate in a traditional sub 6 GHz spectrum, in millimeter wave frequencies, and/or near millimeter wave frequencies in communication with the UE  104 . When the gNB  180  operates in millimeter wave or near millimeter wave frequencies, the gNB  180  may be referred to as a millimeter wave base station. The millimeter wave base station  180  may utilize beamforming  182  with the UE  104  to compensate for the path loss and short range. The base station  180  and the UE  104  may each include a plurality of antennas, such as antenna elements, antenna panels, and/or antenna arrays to facilitate the beamforming. 
     Devices may use beamforming to transmit and receive communication. For example,  FIG. 1  illustrates that a base station  180  may transmit a beamformed signal to the UE  104  in one or more transmit directions  182 ′. The UE  104  may receive the beamformed signal from the base station  180  in one or more receive directions  182 ″. The UE  104  may also transmit a beamformed signal to the base station  180  in one or more transmit directions. The base station  180  may receive the beamformed signal from the UE  104  in one or more receive directions. The base station  180 /UE  104  may perform beam training to determine the best receive and transmit directions for each of the base station  180 /UE  104 . The transmit and receive directions for the base station  180  may or may not be the same. The transmit and receive directions for the UE  104  may or may not be the same. Although beamformed signals are illustrated between UE  104  and base station  102 / 180 , aspects of beamforming may similarly may be applied by UE  104  or RSU  107  to communicate with another UE  104  or RSU  107 , such as based on V2X, V2V, or D2D communication. 
     The EPC  160  may include a Mobility Management Entity (MME)  162 , other MMEs  164 , a Serving Gateway  166 , a Multimedia Broadcast Multicast Service (MBMS) Gateway  168 , a Broadcast Multicast Service Center (BM-SC)  170 , and a Packet Data Network (PDN) Gateway  172 . The MME  162  may be in communication with a Home Subscriber Server (HSS)  174 . The MME  162  is the control node that processes the signaling between the UEs  104  and the EPC  160 . Generally, the MME  162  provides bearer and connection management. All user Internet protocol (IP) packets are transferred through the Serving Gateway  166 , which itself is connected to the PDN Gateway  172 . The PDN Gateway  172  provides UE IP address allocation as well as other functions. The PDN Gateway  172  and the BM-SC  170  are connected to the IP Services  176 . The IP Services  176  may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a PS Streaming Service, and/or other IP services. The BM-SC  170  may provide functions for MBMS user service provisioning and delivery. The BM-SC  170  may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a public land mobile network (PLMN), and may be used to schedule MBMS transmissions. The MBMS Gateway  168  may be used to distribute MBMS traffic to the base stations  102  belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and may be responsible for session management (start/stop) and for collecting eMBMS related charging information. 
     The Core Network  190  may include an Access and Mobility Management Function (AMF)  192 , other AMFs  193 , a Session Management Function (SMF)  194 , and a User Plane Function (UPF)  195 . The AMF  192  may be in communication with a Unified Data Management (UDM)  196 . The AMF  192  is the control node that processes the signaling between the UEs  104  and the Core Network  190 . Generally, the AMF  192  provides QoS flow and session management. All user Internet protocol (IP) packets are transferred through the UPF  195 . The UPF  195  provides UE IP address allocation as well as other functions. The UPF  195  is connected to the IP Services  197 . The IP Services  197  may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a PS Streaming Service, and/or other IP services. 
     The base station may also be referred to as a gNB, Node B, evolved Node B (eNB), an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), a transmit reception point (TRP), or some other suitable terminology. The base station  102  provides an access point to the EPC  160  or Core Network  190  for a UE  104 . Examples of UEs  104  include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, a tablet, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor/actuator, a display, or any other similar functioning device. Some of the UEs  104  may be referred to as IoT devices (e.g., parking meter, gas pump, toaster, vehicles, heart monitor, etc.). The UE  104  may also be referred to as a station, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology. 
       FIG. 2  includes diagrams  200  and  210  illustrating example aspects of slot structures that may be used for sidelink communication (e.g., between UEs  104 , RSU  107 , etc.). The slot structure may be within a 5G/NR frame structure in some examples. In other examples, the slot structure may be within an LTE frame structure. Although the following description may be focused on 5G NR, the concepts described herein may be applicable to other similar areas, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies. The example slot structure in  FIG. 2  is merely one example, and other sidelink communication may have a different frame structure and/or different channels for sidelink communication. A frame (10 ms) may be divided into 10 equally sized subframes (1 ms). Each subframe may include one or more time slots. Subframes may also include mini-slots, which may include 7, 4, or 2 symbols. Each slot may include 7 or 14 symbols, depending on the slot configuration. For slot configuration 0, each slot may include 14 symbols, and for slot configuration 1, each slot may include 7 symbols. Diagram  200  illustrates a single resource block of a single slot transmission, e.g., which may correspond to a 0.5 ms transmission time interval (TTI). A physical sidelink control channel may be configured to occupy multiple physical resource blocks (PRBs), e.g., 10, 12, 15, 20, or 25 PRBs. The PSCCH may be limited to a single sub-channel. A PSCCH duration may be configured to be 2 symbols or 3 symbols, for example. A sub-channel may comprise 10, 15, 20, 25, 50, 75, or 100 PRBs, for example. The resources for a sidelink transmission may be selected from a resource pool including one or more subchannels. As a non-limiting example, the resource pool may include between 1-27 subchannels. A PSCCH size may be established for a resource pool, e.g., as between 10-100% of one subchannel for a duration of 2 symbols or 3 symbols. The diagram  210  in  FIG. 2  illustrates an example in which the PSCCH occupies about 50% of a subchannel, as one example to illustrate the concept of PSCCH occupying a portion of a subchannel. The physical sidelink shared channel (PSSCH) occupies at least one subchannel. The PSCCH may include a first portion of sidelink control information (SCI), and the PSSCH may include a second portion of SCI in some examples. 
     A resource grid may be used to represent the frame structure. Each time slot may include a resource block (RB) (also referred to as physical RBs (PRBs)) that extends 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs). The number of bits carried by each RE depends on the modulation scheme. As illustrated in  FIG. 2 , some of the REs may comprise control information in PSCCH and some Res may comprise demodulation RS (DMRS). At least one symbol may be used for feedback.  FIG. 2  illustrates examples with two symbols for a physical sidelink feedback channel (PSFCH) with adjacent gap symbols. A symbol prior to and/or after the feedback may be used for turnaround between reception of data and transmission of the feedback. The gap enables a device to switch from operating as a transmitting device to prepare to operate as a receiving device, e.g., in the following slot. Data may be transmitted in the remaining REs, as illustrated. The data may comprise the data message described herein. The position of any of the data, DMRS, SCI, feedback, gap symbols, and/or LBT symbols may be different than the example illustrated in  FIG. 2 . Multiple slots may be aggregated together in some examples. 
       FIG. 3  is a block diagram  300  of a first wireless communication device  310  in communication with a second wireless communication device  350 . In some examples, the devices  310  and  350  may communicate based on V2X or other D2D communication. The communication may be based, e.g., on sidelink using a PC5 interface. The devices  310  and the  350  may comprise a UE, an RSU, a base station, etc. Packets may be provided to a controller/processor  375  that implements layer 3 and layer 2 functionality. Layer 3 includes a radio resource control (RRC) layer, and layer 2 includes a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer. 
     The transmit (TX) processor  316  and the receive (RX) processor  370  implement layer 1 functionality associated with various signal processing functions. Layer 1, which includes a physical (PHY) layer, may include error detection on the transport channels, forward error correction (FEC) coding/decoding of the transport channels, interleaving, rate matching, mapping onto physical channels, modulation/demodulation of physical channels, and MIMO antenna processing. The TX processor  316  handles mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols may then be split into parallel streams. Each stream may then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time and/or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator  374  may be used to determine the coding and modulation scheme, as well as for spatial processing. The channel estimate may be derived from a reference signal and/or channel condition feedback transmitted by the device  350 . Each spatial stream may then be provided to a different antenna  320  via a separate transmitter  318 TX. Each transmitter  318 TX may modulate an RF carrier with a respective spatial stream for transmission. 
     At the device  350 , each receiver  354 RX receives a signal through its respective antenna  352 . Each receiver  354 RX recovers information modulated onto an RF carrier and provides the information to the receive (RX) processor  356 . The TX processor  368  and the RX processor  356  implement layer 1 functionality associated with various signal processing functions. The RX processor  356  may perform spatial processing on the information to recover any spatial streams destined for the device  350 . If multiple spatial streams are destined for the device  350 , they may be combined by the RX processor  356  into a single OFDM symbol stream. The RX processor  356  then converts the OFDM symbol stream from the time-domain to the frequency domain using a Fast Fourier Transform (FFT). The frequency domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, and the reference signal, are recovered and demodulated by determining the most likely signal constellation points transmitted by device  310 . These soft decisions may be based on channel estimates computed by the channel estimator  358 . The soft decisions are then decoded and deinterleaved to recover the data and control signals that were originally transmitted by device  310  on the physical channel. The data and control signals are then provided to the controller/processor  359 , which implements layer 3 and layer 2 functionality. 
     The controller/processor  359  can be associated with a memory  360  that stores program codes and data. The memory  360  may be referred to as a computer-readable medium. The controller/processor  359  may provide demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing. The controller/processor  359  is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations. 
     Similar to the functionality described in connection with the transmission by device  310 , the controller/processor  359  may provide RRC layer functionality associated with system information (e.g., MIB, SIBs) acquisition, RRC connections, and measurement reporting; PDCP layer functionality associated with header compression/decompression, and security (ciphering, deciphering, integrity protection, integrity verification); RLC layer functionality associated with the transfer of upper layer PDUs, error correction through ARQ, concatenation, segmentation, and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization. 
     Channel estimates derived by a channel estimator  358  from a reference signal or feedback transmitted by device  310  may be used by the TX processor  368  to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor  368  may be provided to different antenna  352  via separate transmitters  354 TX. Each transmitter  354 TX may modulate an RF carrier with a respective spatial stream for transmission. 
     The transmission is processed at the device  310  in a manner similar to that described in connection with the receiver function at the device  350 . Each receiver  318 RX receives a signal through its respective antenna  320 . Each receiver  318 RX recovers information modulated onto an RF carrier and provides the information to a RX processor  370 . 
     The controller/processor  375  can be associated with a memory  376  that stores program codes and data. The memory  376  may be referred to as a computer-readable medium. The controller/processor  375  provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing. The controller/processor  375  is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations. 
     At least one of the TX processor  368 , the RX processor  356 , and the controller/processor  359  may be configured to perform aspects in connection with the activity indication component  198  of  FIG. 1 . 
     Some communication may be exchanged directly between wireless devices based on sidelink or a PC5 interface rather than being exchanged between a UE and a base station on an access link or Uu link. One non-limiting example of sidelink communication includes vehicle-to-everything (V2X) communication. 
     Sidelink communication may include direct wireless communication between a first device (e.g., a first UE or other sidelink device) and a second device (e.g., a second UE or other sidelink device), e.g., without being routed by a base station. A UE may establish a sidelink communication with another with UE with or without receiving a resource allocation for sidelink communication from the base station. For example, as illustrated in example  400  in  FIG. 4A , a base station  402  may be in communication with a UE  404 A via a Uu link and may be unable to communicate with a UE  404 B via Uu link. The UE  404 A may be in communication with the UE  404 B via a PC5 link to facilitate communications for the UE  404 B. The UE  404 A and the UE  404 B may include the activity indication component  198 . 
     In a first sidelink resource allocation mode (which may be referred to herein as “Mode 1”), centralized resource allocation may be provided by a network entity. For example, a base station  102  or  180  as in  FIG. 1 , may determine resources for sidelink communication and may allocate resources to different UEs  104  to use for sidelink transmissions. In this first mode, a sidelink UE receives the allocation of sidelink resources from the base station  102  or  180 . In a second resource allocation mode (which may be referred to herein as “Mode 2”), distributed resource allocation may be provided. In Mode 2, each UE may autonomously determine resources to use for sidelink transmissions. In order to coordinate the selection of sidelink resources by individual UEs, each UE may use a sensing technique to monitor for resource reservations by other sidelink UEs and may select resources for sidelink transmissions from unreserved resources. In order to use the resources for sidelink transmission, the a UE may transmit SCI indicating a reservation of the resources. 
     To facilitate more efficient sidelink communication, a UE may perform congestion control. As part of the congestion control, the UE may limit one or more transmission parameters in order to reduce the congestion that the UE causes to the communication system. For example, the UE may update (e.g., restrict) one or more of: modulation and coding scheme (MCS) indices and tables, number of sub-channels per transmission, number of retransmissions, transmission power, or the like in order to reduce congestion in the communication system by reducing the CR of the UE. A UE may use CBR as a metric for applying the congestion control procedures by the UE. For example, the UE may estimate or measure the CBR to determine whether the transmission medium is busy. Based on the measured CBR, the UE may limit its own resource utilization, such as by limiting the channel occupancy ratio (CR) to be smaller than a configured threshold when the measured CBR meets a threshold level. To estimate the CBR, the UE may perform RSSI measurements. For example, for PSSCH, the CBR measurement may be based on the fraction of sub-channels for which the UE measures an S-RSSI that exceeds a configured threshold. In some aspects, in order to compute the CBR at slot n, the UE may measure the RSSI for all subchannels between [n−100,n−1], or for the last 100 ms. The CBR indicates how much of the transmission medium is being used by UEs in the communication system. The CR may correspond to an amount of resources used by a particular UE, e.g., the UE measuring the CBR and applying congestion control. The CR may be based on the fraction of sub-channels used for transmission in [n−a, n−1] and granted/reserved in [n, n+b], where a is a positive integer and b is a non-negative integer. For example, a+b+1 may be 1000 and a may be greater than or equal to 500. 
     The UE may need to be on to measure the RSSI and compute the CBR, which may reduce the battery life of the UE. However, a power-saving UE with power-saving techniques, such as DRX, WUS indication, BW adaptation via BWP switch or resource pool activation/deactivation, Scell activation/deactivation, or the like, may not be continuously on to compute the CBR. Aspects that enable UEs to detect activities and measure CBR using a set of congestion control measurement resources are provided. 
       FIGS. 5A and 5B  illustrate examples  500  and  550  of power-saving mechanisms for a UE. As illustrated in  FIG. 5A , for sidelink DRX, within a resource pool  502 , the UE may be on (during the DRX duration  506 ) or asleep (during the sleep  508 ) within a DRX cycle  504 . The sleep and wake cycle, or cycle of DRX ON, DRX OFF durations enable the UE to conserve battery power during periods in which the UE is in a lower power mode (e.g., the sleep mode, DRX OFF duration, etc.). In the low power mode, the UE may skip reception of sidelink communication. As illustrated in  FIG. 5B , for a UE with power-saving utilizing WUS, within a resource pool  552 , the UE may be in a WUS monitoring period  554 . During the monitoring duration of the WUS monitoring period, if the UE detects a WUS  553 , the UE may stay awake (e.g., during the stay awake duration  556 ). If the UE does not detect the WUS  553  during the monitoring duration of the WUS monitoring period, the UE may be asleep (e.g., during the sleep duration  558 ). Thus, the use of a WUS may enable a DRX UE to more efficiently remain in a low power mode when no transmission may be transmitted to the UE. For a UE that uses these power-saving mechanisms, the UE might not be able to perform CBR measurements when the UE is in the lower power mode, e.g., asleep, during the DRX OFF duration, etc. 
       FIGS. 6A and 6B  illustrate example bandwidth adaptation mechanisms for power-saving for a UE. The bandwidth adaptation mechanisms may enable the UE to monitor a reduced bandwidth, at times, which may reduce the power used by the UE. As illustrated in example  600  of  FIG. 6A , a UE may receive a small amount of data (e.g., data  604 ) within a BWP/resource pool  602 . In some aspects, the small amount of data may be voice communication data (e.g., of a size of 30 Kilobit per second ((Kbps)). After receiving an indication  606  indicating a larger amount of incoming data to be received, the UE may switch to a larger BWP/resource pool  610  to receive a larger amount of incoming data (e.g., ldata  608 ). In some aspects, the larger amount of incoming data may include high definition video or streaming data (e.g., of a size of 1 Megabits per second (Mbps)). There may be a switching time  606 A when the UE switches from the BWP/resource pool  602  to the larger BWP/resource pool  610 . After a period of receiving no data (e.g., no data  612 ), the UE may switch back to the narrower BWP/resource pool  602 . Similarly, there may be a switching time  606 B when the UE switches from the BWP/resource pool  610  to the BWP/resource pool  602 . As illustrated in example  650  of  FIG. 6B , a UE may dynamically activate/deactivate a resource pool based on traffic. For example, after receiving an SCI  652 A and a PSSCH  654 A in a first resource pool, the UE may anticipate more traffic and activate the second resource pool (e.g., at activation  656 ). The UE may receive a second SCI  652 B and a second PSSCH  654 B. The UE may deactivate the second resource pool (e.g., at activation  658 ), such as after the UE no longer expects a large amount of traffic. The use of the larger BWP/resource pool may enable the UE to efficiently receive the larger data, whereas the transition back to the narrower BWP/resource pool may help to reduce power use at the UE. In a UE that utilize such types of bandwidth adaptation, the UE might not be able to perform CBR measurements on the larger/second BWP/resource pool when the UE is not utilizing it. 
     Aspects described herein enable those power-saving UEs to perform measurements in the corresponding resource pool/BWP using a set of CBR measurement occasions.  FIG. 7  illustrates example  700  of such a congestion control mechanism. The UE may measure RSSI in a resource pool  702  during both DRX on durations  704  and sleep durations  706 . As illustrated in example  800  of  FIG. 8 , a UE may be configured with a set of congestion control measurement resources  804  in the frequency and time domain within a resource pool  802 . In some aspects, the set of congestion control measurement resources  804  may include resources that can be used as either transmitting and receiving resources (e.g., occasions) and may be configured/preconfigured to the UE. The UE may transmit signals (such as activity indication signals) on the transmitting resources (e.g., occasions to transmit activity indication) for other UEs to measure its activity. The UE may measure the RSSI of the signals transmitted from other UEs on the receiving resources (e.g., occasions to measure RSSI). In some aspects, the same set of time/frequency domain congestion control measurement resources may be configured/preconfigured to all UEs who may communicate over sidelink in the resource pool  802 . In some aspects, the determination of transmitting/receiving resources partition within the set of congestion control measurement resources (e.g., which resources in the set of congestion control measurement resources are transmitting resources and which resources in the set of congestion control measurement resources are receiving resources) may be UE-specific and determined by the respective UEs. Instead of performing RSSI measurements based on PSSCH/PSCCH, the UE may perform RSSI measurements based on the activity indication signals transmitted by other UEs. Similarly, other UEs may perform RSSI measurements based on the activity indication signal transmitted by the UE. In some aspects, the activity indication signals do not include data to be decoded by another UE and the activity may be detected based on the presence of the signal (e.g., a signal with a transmission power higher than a threshold). 
     In some aspects, the determination of transmitting/receiving resources partition within the set of congestion control measurement resources may be based on past or future UE transmission activities. In some aspects, as illustrated in example  900  of  FIG. 9 , sets of congestion control measurement resources  904 A and  904 B are periodically configured within a resource pool  902 . There may be a mapping (e.g., a 1-to-1 or non 1-to-1 mapping) that maps resources in the communication pool (e.g., resources  906 A and  906 B in the communication resources  908 A and  908 B) to a (smaller in size) resource in the measurement sets (e.g., congestion control measurement resources  904 A or  904 B). If a UE has transmitted or plans to transmit in a resource in the communication pool in a period, the UE may transmit, such as transmit an activity indication, in a corresponding resource (mapped) in the measurement set (e.g., congestion control measurement resources  904 A or  904 B). The activity indication may be separate from communication channels, such as PSSCH or PSCCH. The activity indication signal may be a dedicated signal that the UE transmits in a particular resource to indicate an intention to transmit a sidelink transmission or to indicate that a sidelink transmission from the UE has been performed in the past, e.g., without explicitly indicating information about the sidelink transmission. For example, in some aspects, if the UE has transmitted in resource  906 A in the communication resources  908 A, the UE may transmit an activity indication signal in the corresponding resource that is mapped to the resource  906 A in the congestion control measurement resources  904 B. In some aspects, every resource in the communication resources  908 A maps to a resource in the measurement resources  904 B, where the measurement resources may always occur later in time than the communication resources  908 A. In another example, in some aspects, if the UE plans to transmit in resource  906 B in the communication resources  908 B, the UE may transmit an activity indication signal in the corresponding resource that is mapped to the resource  906 B in the congestion control measurement resources  904 B. In some aspects, every resource in the communication resources  908 B maps to a resource in the measurement resources  904 B, where the measurement resources may always occur earlier in time than the communication resources  908 A. For example, a particular activity indication resource may correspond to a subchannel in sidelink communication resources. Based on such mapping, the activities in the measurement set (e.g., the congestion control measurement resources) may provide a compressed summary of the actual activities in the communication pool. In some aspects, the UE may use the same power to transmit the communication and the activity indication. In some aspects, the UE may measure RSSI (e.g., receive and measure RSSI) in the rest of the measurement set (congestion control measurement resources) in which the UE does not transmit an activity indication. 
     In some aspects, the determination of transmitting/receiving resources partition within the set of congestion control measurement resources may be based on a pattern (such as a pseudo-random pattern). In some aspects, a set of congestion control measurement resources may be periodically configured within a resource pool. As illustrated in example  1000  of  FIG. 10 , resources in the set of congestion control measurement resources within a resource pool  1002  may not be consecutive in time. The UE may transmit (e.g., transmit activity indication) in X % of resources in the set of the congestion control measurement resources and receive (i.e., measure RSSI in the rest of resources in the set of the congestion control measurement resources. The number X may be determined based on the number of communication resources that the UE has used or plans to use, a traffic buffer status, or the like. In some aspects, the selection of the X % resources may be based on the UE identifier (ID), a pseudo-random pattern, a random selection, or the like. Thus, in some examples, there may not be a relationship between the resource for the activity indication and the resources that will be used to transmit the sidelink communication, yet the activity indication signal may still be used for CBR measurements and CR purposes. 
       FIG. 11  is a flowchart  1100  of a method of wireless communication. The method may be performed by a UE (e.g., the UE  104 , the UE  704 A/B/C/D, the UE described in connection with  FIGS. 5-10 , the apparatus  1202 ). Optional aspects are illustrated with a dashed line. 
     At  1102 , the UE may operate in a power saving mode. For example, the operating  1102  may be performed by power saving component  1242  in  FIG. 12 . 
     At  1104 , the UE may wake up from a low power state based on the power saving mode to perform a measurement or a transmission in the set of congestion control measurement resources. For example, the waking up  1104  may be performed by waking up component  1244  in  FIG. 12 . 
     At  1106 , the UE may determine a configuration of a set of congestion control measurement resources comprising one or more receiving resources and one or more transmitting resources for transmission of an activity indication signal for sidelink communication. For example, the determination  1106  may be performed by resources determination component  1246  in  FIG. 12 . In some aspects, the configuration comprises periodic occasions. In some aspects, the one or more receiving resources are associated with configured frequency resources and a subset of active frequency resources within the configured resources. In some aspects, the UE measures the RSSI in the configured frequency resources. In some aspects, the configuration of the set of congestion control measurement resources does not comprise an automatic gain control (AGC) symbol or a GAP symbol between the one or more receiving resources and the one or more transmitting resources. For example, in some aspects, the sidelink UEs do not need to decode any messages from the measurement resources, instead, the sidelink UEs may only need to measure the received power (e.g., RSSI) on the measurement resources. In some aspects, the set of congestion control measurement resources is shared with one or more other sidelink devices and the one or more transmitting resources are specific to the UE. In some aspects, the UE further determines the one or more receiving resources and the one or more transmitting resources for the UE. In some aspects, the UE determines the one or more transmitting resources for the activity indication based on resources that map to a past sidelink transmission. In some aspects, the UE determines the one or more transmitting resources for the activity indication based on resources that map to communication resources for a sidelink transmission. In some aspects, determining the one or more receiving resources comprises determining resources in the set of congestion control measurement resources that are not the one or more transmitting resources as the one or more receiving resources. In some aspects, the UE determines the one or more transmitting resources as a percentage of the congestion control measurement resources based on an amount of communication resources for a sidelink transmission from the UE. In some aspects, the UE determines the one or more transmitting resources as a percentage of the congestion control measurement resources based on a traffic buffer status. In some aspects, the set of congestion control measurement resources is non-consecutive in time. In some aspects, the set of congestion control measurement resources is consecutive in time. 
     At  1108 , the UE may measure RSSI on at least one of the one or more receiving resources. For example, the measurement  1108  may be performed by RSSI measurement component  1248  in  FIG. 12 . In some aspects, the UE measures the RSSI on the at least one of the one or more receiving resources without decoding a signal received in the at least one of the one or more receiving resources. In some aspects, the UE may only transmit the indication signal within the active BWP/resource pool/CC and the UE may measure RSSI within all configured BWPs/resource pools/CCs. 
     At  1110 , the UE may perform at least one of a CBR measurement or a CR measurement based on the set of congestion control measurement resources. For example, the measurement  1110  may be performed by CBR measurement component  1250  in  FIG. 12 . 
     At  1112 , the UE may transmit an activity indication using the one or more transmitting resources in an occasion of the set of congestion control measurement resources. For example, the transmission  1112  may be performed by activity indication component  1252  in  FIG. 12 . In some aspects, the activity indication is for RSSI measurements for computing a CBR by one or more other sidelink devices. In some aspects, the UE may transmit the activity indication within the subset of active frequency resources. For example, the UE may transmit the activity indication within the active BWP, the active resource pool, or the active component carrier. In some aspects, transmitting the activity indication comprises transmitting a known sequence. In some aspects, the UE may transmit the activity indication in a resource within the congestion control measurement resources based on a UE ID of the UE. In some aspects, the UE transmits the activity indication in a resource within the congestion control measurement resources based on a pseudo-random pattern. In some aspects, the UE transmits the activity indication in a resource within the congestion control measurement resources based on a random selection. In some aspects, the UE may transmit the activity indication using a sequence (e.g., a configured sequence), the UE may not convey any additional information in transmitting the activity indication. 
     At  1114 , the UE may transmit sidelink control information indicating resources for the sidelink transmission and transmit the sidelink transmission in one or more communication resources. For example, the transmission  1114  may be performed by sidelink transmission component  1254  in  FIG. 12 . In some aspects, the UE transmits the sidelink transmission in the communication resources using a same transmission power as for the activity indication. In some aspects, the sidelink transmission occurs prior to the activity indication. In some aspects, the sidelink transmission occurs after the activity indication. 
       FIG. 12  is a diagram  1200  illustrating an example of a hardware implementation for an apparatus  1202 . The apparatus  1202  is a UE and includes a cellular baseband processor  1204  (also referred to as a modem) coupled to a cellular RF transceiver  1222  and one or more subscriber identity modules (SIM) cards  1220 , an application processor  1206  coupled to a secure digital (SD) card  1208  and a screen  1210 , a Bluetooth module  1212 , a wireless local area network (WLAN) module  1214 , a Global Positioning System (GPS) module  1216 , and a power supply  1218 . The cellular baseband processor  1204  communicates through the cellular RF transceiver  1222  with the UE  104  and/or BS  102 / 180 . The cellular baseband processor  1204  may include a computer-readable medium/memory. The computer-readable medium/memory may be non-transitory. The cellular baseband processor  1204  is responsible for general processing, including the execution of software stored on the computer-readable medium/memory. The software, when executed by the cellular baseband processor  1204 , causes the cellular baseband processor  1204  to perform the various functions described supra. The computer-readable medium/memory may also be used for storing data that is manipulated by the cellular baseband processor  1204  when executing software. The cellular baseband processor  1204  further includes a reception component  1230 , a communication manager  1232 , and a transmission component  1234 . The communication manager  1232  includes the one or more illustrated components. The components within the communication manager  1232  may be stored in the computer-readable medium/memory and/or configured as hardware within the cellular baseband processor  1204 . The cellular baseband processor  1204  may be a component of the UE  350  and may include the memory  360  and/or at least one of the TX processor  368 , the RX processor  356 , and the controller/processor  359 . In one configuration, the apparatus  1202  may be a modem chip and include just the baseband processor  1204 , and in another configuration, the apparatus  1202  may be the entire UE (e.g., see  350  of  FIG. 3 ) and include the aforediscussed additional modules of the apparatus  1202 . 
     The communication manager  1232  includes a power saving component  1242  that operates in a power saving mode, e.g., as described in connection with  1102  of  FIG. 11 . The communication manager  1232  may further include a wake up component  1244  that wakes up from a low power state based on the power saving mode to perform a measurement or a transmission in the set of congestion control measurement resources, e.g., as described in connection with  1104  of  FIG. 11 . The communication manager  1232  may further include a resources determination component  1246  that determines a configuration of a set of congestion control measurement resources comprising one or more receiving resources and one or more transmitting resources for transmission of an activity indication signal for sidelink communication, e.g., as described in connection with  1106  of  FIG. 11 . The communication manager  1232  may further include a RSSI measurement component  1248  that measures RSSI on at least one of the one or more receiving resources, e.g., as described in connection with  1108  of  FIG. 11 . The communication manager  1232  may further include a CBR measurement component  1250  that performs at least one of a CBR measurement or a CR measurement based on the set of congestion control measurement resources, e.g., as described in connection with  1110  of  FIG. 11 . The communication manager  1232  may further include an activity indication component  1252  that transmits an activity indication using the one or more transmitting resources in an occasion of the set of congestion control measurement resources, e.g., as described in connection with  1112  of  FIG. 11 . The communication manager  1232  may further include a sidelink transmission component  1254  that transmits sidelink control information indicating resources for the sidelink transmission and transmits the sidelink transmission in one or more communication resources, e.g., as described in connection with  1114  of  FIG. 11 . 
     The apparatus may include additional components that perform each of the blocks of the algorithm in the aforementioned flowchart of  FIG. 11 . As such, each block in the aforementioned flowchart of  FIG. 11  may be performed by a component and the apparatus may include one or more of those components. The components may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof. 
     In one configuration, the apparatus  1202 , and in particular the baseband cellular processor  1204 , includes means for determining a configuration of a set of congestion control measurement resources comprising one or more receiving resources and one or more transmitting resources for transmission of an activity indication signal for sidelink communication. The baseband cellular processor  1204  may further include means for measuring RSSI on at least one of the one or more receiving resources. The baseband cellular processor  1204  may further include means for operating in a power saving mode. The baseband cellular processor  1204  may further include means for performing at least one of a CBR measurement or a CR measurement based on the set of congestion control measurement resources. The baseband cellular processor  1204  may further include means for waking up from a low power state based on the power saving mode to perform a measurement or a transmission in the set of congestion control measurement resources. The baseband cellular processor  1204  may further include means for transmitting an activity indication using the one or more transmitting resources in an occasion of the set of congestion control measurement resources. The baseband cellular processor  1204  may further include means for transmitting sidelink control information indicating resources for the sidelink transmission. The baseband cellular processor  1204  may further include means for transmitting the sidelink transmission in one or more communication resources. The baseband cellular processor  1204  may further include means for transmitting an activity indication within the subset of active frequency resources. The baseband cellular processor  1204  may further include means for transmitting a known sequence. The baseband cellular processor  1204  may further include means for determining the one or more receiving resources and the one or more transmitting resources for the UE. The baseband cellular processor  1204  may further include means for transmitting the sidelink transmission in the communication resources using a same transmission power as for the activity indication. The baseband cellular processor  1204  may further include means for transmitting the activity indication in a resource within the congestion control measurement resources based on a UE ID of the UE. The baseband cellular processor  1204  may further include means for transmitting the activity indication in a resource within the congestion control measurement resources based on a pseudo-random pattern. The baseband cellular processor  1204  may further include means for transmitting the activity indication in a resource within the congestion control measurement resources based on a random selection. 
     The aforementioned means may be one or more of the aforementioned components of the apparatus  1202  configured to perform the functions recited by the aforementioned means. As described supra, the apparatus  1202  may include the TX Processor  368 , the RX Processor  356 , and the controller/processor  359 . As such, in one configuration, the aforementioned means may be the TX Processor  368 , the RX Processor  356 , and the controller/processor  359  configured to perform the functions recited by the aforementioned means. 
     It is understood that the specific order or hierarchy of blocks in the processes/flowcharts disclosed is an illustration of example approaches. Based upon design preferences, it is understood that the specific order or hierarchy of blocks in the processes/flowcharts may be rearranged. Further, some blocks may be combined or omitted. The accompanying method claims present elements of the various blocks in a sample order, and are not meant to be limited to the specific order or hierarchy presented. 
     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. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein 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.” Terms such as “if,” “when,” and “while” should be interpreted to mean “under the condition that” rather than imply an immediate temporal relationship or reaction. That is, these phrases, e.g., “when,” do not imply an immediate action in response to or during the occurrence of an action, but simply imply that if a condition is met then an action will occur, but without requiring a specific or immediate time constraint for the action to occur. 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. Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C,” “one or more of A, B, or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or any combination thereof” include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as “at least one of A, B, or C,” “one or more of A, B, or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or any combination thereof” may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or C. 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. The words “module,” “mechanism,” “element,” “device,” and the like may not be a substitute for the word “means.” As such, no claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for.” 
     The following aspects are illustrative only and may be combined with other aspects or teachings described herein, without limitation. 
     Aspect 1 is a method of wireless communication at a UE, comprising: determining a configuration of a set of congestion control measurement resources comprising one or more receiving resources and one or more transmitting resources for transmission of an activity indication signal for sidelink communication; and measuring RSSI on at least one of the one or more receiving resources. 
     Aspect 2 is the method of aspect 1, further comprising: operating in a power saving mode; and performing at least one of a CBR measurement or a CR measurement based on the set of congestion control measurement resources. 
     Aspect 3 is the method of any of aspects 1-2, further comprising: waking up from a low power state based on the power saving mode to perform a measurement or a transmission in the set of congestion control measurement resources. 
     Aspect 4 is the method of any of aspects 1-3, further comprising: transmitting an activity indication using the one or more transmitting resources in an occasion of the set of congestion control measurement resources. 
     Aspect 5 is the method of any of aspects 1-4, further comprising: transmitting sidelink control information indicating resources for the sidelink transmission; and transmitting the sidelink transmission in one or more communication resources. 
     Aspect 6 is the method of any of aspects 1-5, wherein the configuration comprises periodic occasions. 
     Aspect 7 is the method of any of aspects 1-6, wherein the activity indication is for RSSI measurements for computing a CBR by one or more other sidelink devices. 
     Aspect 8 is the method of any of aspects 1-7, wherein the one or more receiving resources are associated with configured frequency resources and a subset of active frequency resources within the configured resources, wherein the UE measures the RSSI in the configured frequency resources. 
     Aspect 9 is the method of any of aspects 1-8, further comprising: transmitting an activity indication within the subset of active frequency resources. 
     Aspect 10 is the method of any of aspects 1-9, wherein the configured frequency resources comprises one or more of: one or more resource pools, one or more sidelink BWPs, or one or more sidelink component carriers. 
     Aspect 11 is the method of any of aspects 1-10, wherein transmitting the activity indication comprises transmitting a known sequence. 
     Aspect 12 is the method of any of aspects 1-11, wherein the configuration of the set of congestion control measurement resources does not comprise an AGC symbol or a GAP symbol between the one or more receiving resources and the one or more transmitting resources. 
     Aspect 13 is the method of any of aspects 1-12, wherein the set of congestion control measurement resources is shared with one or more other sidelink devices and the one or more transmitting resources are specific to the UE. 
     Aspect 14 is the method of any of aspects 1-13, further comprising: determining the one or more receiving resources and the one or more transmitting resources for the UE. 
     Aspect 15 is the method of any of aspects 1-14, wherein the UE determines the one or more transmitting resources for the activity indication based on resources that map to a past sidelink transmission. 
     Aspect 16 is the method of any of aspects 1-15, wherein the UE determines the one or more transmitting resources for the activity indication based on resources that map to communication resources for a sidelink transmission. 
     Aspect 17 is the method of any of aspects 1-16, further comprising: transmitting the sidelink transmission in the communication resources using a same transmission power as for the activity indication. 
     Aspect 18 is the method of any of aspects 1-17, wherein determining the one or more receiving resources comprises determining resources in the set of congestion control measurement resources that are not the one or more transmitting resources as the one or more receiving resources. 
     Aspect 19 is the method of any of aspects 1-18, wherein the UE determines the one or more transmitting resources as a percentage of the congestion control measurement resources based on an amount of communication resources for a sidelink transmission from the UE. 
     Aspect 20 is the method of any of aspects 1-19, wherein the sidelink transmission occurs prior to the activity indication. 
     Aspect 21 is the method of any of aspects 1-20, wherein the sidelink transmission occurs after the activity indication. 
     Aspect 22 is the method of any of aspects 1-21, wherein the UE determines the one or more transmitting resources as a percentage of the congestion control measurement resources based on a traffic buffer status. 
     Aspect 23 is the method of any of aspects 1-22, further comprising: transmitting the activity indication in a resource within the congestion control measurement resources based on a UE ID of the UE. 
     Aspect 24 is the method of any of aspects 1-23, further comprising: transmitting the activity indication in a resource within the congestion control measurement resources based on a pseudo-random pattern. 
     Aspect 25 is the method of any of aspects 1-24, further comprising: transmitting the activity indication in a resource within the congestion control measurement resources based on a random selection. 
     Aspect 26 is the method of any of aspects 1-25, wherein the set of congestion control measurement resources is non-consecutive in time. 
     Aspect 27 is the method of any of aspects 1-26, wherein the set of congestion control measurement resources is consecutive in time. 
     Aspect 28 is the method of any of aspects 1-27, wherein the UE measures the RSSI on the at least one of the one or more receiving resources without decoding a signal received in the at least one of the one or more receiving resources. 
     Aspect 29 is an apparatus for wireless communication including at least one processor coupled to a memory and configured to implement a method as in any of aspects 1 to 28. 
     Aspect 30 is an apparatus for wireless communication including means for implementing a method as in any of aspects 1 to 28. 
     Aspect 31 is a computer-readable medium storing computer executable code, where the code when executed by a processor causes the processor to implement a method as in any of aspects 1 to 28.