Transceiver calibration during silent periods

Abstract

The apparatus operates to communicate with a second wireless device during active periods and performs radio impairment calibration during periodic silent periods. The calibration may include receiver calibration, for example, including gain state training. The calibration may include transmitter calibration.

Description

[0001] priority

[0002] This patent application claims priority to non-provisional application No. 16 / 577,184, filed on September 20, 2019, entitled “TRANSCEIVER CALIBRATIONS ATSILENT PERIODS,” which has been assigned to the assignee of the present application and is hereby expressly incorporated herein by reference.

[0003] introduction

[0004] The present disclosure relates generally to communication systems, and more particularly to vehicle-to-vehicle (V2V), vehicle-to-everything (V2X), or other device-to-device (D2D) communications.

[0005] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcast. 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.

[0006] These multiple access technologies have been adopted in various telecommunication standards to provide common protocols that enable different wireless devices to communicate at city, country, region, and even global levels. An example telecommunication standard is 5G New Radio (NR). 5G NR is a part of the continuous mobile broadband evolution promulgated by the Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with the Internet of Things (IoT)) and other requirements. 5GNR includes services associated with enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliable low latency communication (URLLC). Some aspects of 5G NR may be based on 4G Long Term Evolution (LTE) standards. Various aspects of wireless communication may include direct communication between devices, such as in V2X, V2V, and / or other D2D communications. The improvements presented herein may be applicable to V2X, V2V, and / or other D2D technologies and other multiple access technologies and telecommunication standards that employ these technologies.

[0007] Overview

[0008] A brief summary of one or more aspects is given below to provide a basic understanding of such aspects. This summary is not an exhaustive overview of all conceived aspects, and is neither intended to identify the key or critical elements of all aspects nor to define 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 a more detailed description that will be presented later.

[0009] In one aspect of the present disclosure, a method for wireless communication at a first wireless device is provided. The method includes communicating with a second wireless device during an active period and performing radio impairment calibration during a periodic silent period.

[0010] In another aspect of the present disclosure, an apparatus for wireless communication at a first wireless device is provided. The apparatus communicates with a second wireless device during an active period. The apparatus performs radio impairment calibration during the periodic silent period.

[0011] In another aspect of the disclosure, an apparatus for wireless communication at a first wireless device is provided. The apparatus includes means for communicating with a second wireless device during an active period and means for performing radio impairment calibration during a periodic silent period.

[0012] In another aspect of the present disclosure, a computer readable medium storing computer executable code for wireless communication at a first wireless device is provided. The code, when executed by a processor, causes the processor to communicate with a second wireless device during an active period and perform radio impairment calibration during a periodic silent period.

[0013] In another aspect of the disclosure, the periodic silence period includes at least one symbol of the subframe. In another aspect of the disclosure, the periodic silence period may include the last symbol of the subframe. In another aspect of the disclosure, the first wireless device may communicate with the second wireless device based on at least one of V2X, V2V, or other D2D communications. In another aspect of the disclosure, the radio impairment calibration may include at least one of a direct current (DC) offset calibration or an in-phase quadrature (IQ) imbalance calibration. In another aspect of the disclosure, the first wireless device may select a gain state to be calibrated; perform measurements for the selected gain state during the periodic silence period; and update the DC measurement for the selected gain state. In another aspect of the disclosure, the first wireless device may select an untrained gain state or an older gain state with an older measurement than another gain state. In another aspect of the disclosure, the first wireless device may determine whether the measurement includes a signal power above a threshold, wherein the DC measurement for the selected gain state is updated when the signal power is not above the threshold, and the measurement is discarded when the measurement includes a signal power above the threshold. In another aspect of the disclosure, the first wireless device may transmit during the active period and may switch from a transmit mode to a receive mode to perform the radio impairment calibration during the periodic silent period. In another aspect of the disclosure, the first wireless device may transmit during the active mode; and may transmit a transmission below a transmit power level threshold during the periodic silent period; and measure the transmission using a receiver of the first wireless device as part of performing the radio impairment calibration. In another aspect of the disclosure, the radio impairment calibration may include a loopback calibration.

[0014] To achieve the foregoing and related ends, the one or more aspects include the features fully described below and particularly pointed out in the claims. The following description and drawings set forth in detail certain illustrative features of the one or more aspects. However, these features are merely indicative of several of the various ways in which the principles of the various aspects may be employed, and this description is intended to cover all such aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a diagram illustrating an example of a wireless communication system and an access network.

[0017] Figure 2 Various example aspects of a sidelink slot structure are illustrated.

[0018] Figure 3 is a diagram illustrating an example of a first device and a second device participating in wireless communication.

[0019] Figure 4Examples of devices in wireless communications based on, for example, V2V, V2X, and / or other D2D communications are illustrated.

[0020] Figure 5 Various example components of a wireless device are illustrated.

[0021] Figure 6 Various example components of a wireless device are illustrated.

[0022] Figure 7 Various examples of active periods and quiet periods are explained.

[0023] Figure 8 An example communication flow between wireless devices is illustrated.

[0024] Fig. 9 is a flow chart of a wireless communication method.

[0025] Fig.10 is a conceptual data flow diagram illustrating the flow of data between different devices / components in an example arrangement.

[0026] Fig.11 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

[0027] Detailed Description

[0028] The detailed description set forth below in conjunction with the accompanying 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. This detailed description includes specific details to provide a thorough understanding of the 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 diluting such concepts.

[0029] Various aspects presented herein enable a wireless device to perform transceiver calibration during a silent period. This calibration can improve communication for a device communicating in burst mode, for example, where there may not be a continuous loop operating at a receiver and / or transmitter in burst mode. Calibration can be performed for a receiver and / or for a receiver. For example, a receiver can select an untrained gain state and / or a gain state based on an older measurement for performing calibration. Such selection can help the wireless device to maintain more accurate calibration information, which can be applied on demand during an active period. As an example, V2X communications (such as CV2X communications) can change from one subframe to another subframe with different frequency allocations and received signal powers. This communication may include a low duty cycle with infrequent transmissions. Calibration performed during a silent period can improve communication for this device during an active period.

[0030] 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 on the specific application and the design constraints imposed on the overall system.

[0031] As an example, an element, or any part of an element, or any combination of elements may be implemented as a "processing system" including 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 chip (SoCs), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gating logic, discrete hardware circuits, and other suitable hardware configured to perform various functionalities described throughout this disclosure. One or more processors in a processing system may execute software. Software should be broadly interpreted as meaning instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether it is described in software, firmware, middleware, microcode, hardware description languages, or other terms.

[0032] Accordingly, in one or more examples, the functions described can be implemented in hardware, software, or any combination thereof. If implemented in software, each function can be stored or encoded as one or more instructions or codes on a computer-readable medium. Computer-readable media include computer storage media. Storage media can be any available media that can be accessed by a computer. As an example and not limitation, such computer-readable media can include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, a combination of computer-readable media of the aforementioned types, or any other medium that can be used to store instructions or data structures in the form of computer executable code that can be accessed by a computer.

[0033] Figure 11 is a diagram illustrating an example of a wireless communication system and access network 100. The wireless communication system (also referred to as a wireless wide area network (WWAN)) includes a base station 102, a UE 104, an evolved packet core (EPC) 160, and a core network (e.g., 5GC) 190. The base station 102 may include a macro cell (a high-power cellular base station) and / or a small cell (a low-power cellular base station). A macro cell includes a base station. A small cell includes a femto cell, a pico cell, and a micro cell.

[0034] 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 EPC 160 via a backhaul link 132 (e.g., an S1 interface). Base stations 102 configured for NR (collectively referred to as Next Generation RAN (NG-RAN)) may interface with core network 190 via a backhaul link 184. Base stations 102 may perform one or more of the following functions, among other functions: delivery of user data, radio channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment tracking, RAN information management (RIM), paging, positioning, and delivery of alert messages. Base stations 102 may communicate with each other directly or indirectly (eg, through EPC 160 or core network 190) over backhaul links 134 (eg, X2 interfaces). Backhaul links 134 may be wired or wireless.

[0035] Base stations 102 may communicate wirelessly with UEs 104. Each base station 102 may provide communication coverage for a respective geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, a small cell 102' may have a coverage area 110' that overlaps with the coverage area 110 of one or more base stations 102 (such as a macro base station). A network including small cells and macro cells may be referred to as a heterogeneous network. A heterogeneous network may also include a home evolved Node B (eNB) (HeNB), which may provide services to a restricted group referred to as a closed subscriber group (CSG). A communication link 120 between a base station 102 and a UE 104 may include an uplink (UL) (also referred to as a reverse link) transmission from the UE 104 to the base station 102 and / or a downlink (DL) (also referred to as a forward link) transmission from the base station 102 to the UE 104. The communication link 120 may use multiple-input multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and / or transmit diversity. These communication links may be over one or more carriers. For each carrier allocated in a carrier aggregation of up to Yx MHz (x component carriers) for transmission in each direction, the base station 102 / UE 104 may use a spectrum of up to Y MHz (e.g., 5, 10, 15, 20, 100, 400 MHz, etc.) bandwidth. These carriers may or may not be adjacent to each other. The allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated to DL compared to UL). The component carrier may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell), and the secondary component carrier may be referred to as a secondary cell (SCell).

[0036] Some UEs 104 may communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 may use 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). The D2D communication may be through a variety of wireless D2D communication systems, such as, for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

[0037] The wireless communication system may further include a Wi-Fi access point (AP) 150 communicating with a Wi-Fi station (STA) 152 in the 5 GHz unlicensed spectrum via a communication link 154. When communicating in the unlicensed spectrum, the STA 152 / AP 150 may perform a clear channel assessment (CCA) to determine whether the channel is available prior to communication.

[0038] The small cell 102' may operate in a licensed and / or unlicensed spectrum. When operating in an unlicensed spectrum, the small cell 102' may employ NR and use the same 5 GHz unlicensed spectrum as used by the Wi-Fi AP 150. The small cell 102' employing NR in the unlicensed spectrum may boost the coverage of the access network and / or increase the capacity of the access network.

[0039] Whether it is a small cell 102' or a large cell (e.g., a macro base station), the base station 102 may include an eNB, a gB node (gNB), or other types of base stations. Some base stations 180 (such as gNBs) may operate in traditional sub-6 GHz spectrum, millimeter wave (mmW) frequencies, and / or near mmW frequencies to communicate with UE 104. When the gNB operates in mmW or near mmW frequencies, the gNB may be referred to as a mmW base station. Extremely high frequency (EHF) is part of the RF in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and a wavelength between 1 mm and 10 mm. The radio waves in this band may be referred to as millimeter waves. Near mmW can be extended down to 3 GHz frequencies with a wavelength of 100 mm. The super high frequency (SHF) band extends between 3 GHz and 30 GHz, which is also referred to as centimeter waves. Communications using mmW / near mmW radio frequency bands have extremely high path loss and short range. A mmW base station (eg, base station 180 ) may utilize beamforming 182 with UE 104 to compensate for extremely high path loss and short range.

[0040] Devices can use beamforming to transmit and receive communications. For example, Figure 1It is illustrated that the base station 180 may transmit beamformed signals to the UE 104 in one or more transmission directions 182'. UE 104 may receive beamformed signals from base station 180 in one or more receive directions 182″. UE 104 may also transmit beamformed signals to base station 180 in one or more transmit directions. Base station 180 may receive beamformed signals from UE 104 in one or more receive directions. Base station 180 / UE 104 may perform beam training to determine the best receive direction and transmit direction for each of base station 180 / UE 104. The transmit direction and receive direction of base station 180 may be the same or may be different. The transmit direction and receive direction of UE 104 may be the same or may be different. Although the beamformed signals are illustrated between UE 104 and base station 102 / 180, various aspects of beamforming may be similarly applied by UE 104 or RSU 107 to communicate with other UEs 104 or RSUs 107, such as for communications based on V2X, V2V, or D2D.

[0041] 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 a control node that handles signaling between the UE 104 and the EPC 160. In general, the MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are delivered through the serving gateway 166, which itself is connected to the PDN gateway 172. The PDN gateway 172 provides UE IP address allocation and other functions. The PDN gateway 172 and the BM-SC 170 are connected to 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 functionality for MBMS user service provisioning and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS transmissions, 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 base stations 102 belonging to a multicast broadcast single frequency network (MBSFN) area that broadcasts a specific service, and may be responsible for session management (start / stop) and for collecting eMBMS-related charging information.

[0042] 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. AMF 192 may be in communication with a unified data management (UDM) 196. AMF 192 is a control node that handles signaling between UE 104 and the core network 190. In general, AMF 192 provides QoS flow and session management. All user Internet Protocol (IP) packets are delivered through UPF 195. UPF 195 provides UE IP address allocation and other functions. UPF 195 is connected to IP services 197. IP services 197 may include the Internet, an intranet, an IP multimedia subsystem (IMS), a PS streaming service, and / or other IP services.

[0043] A base station may also be referred to as a gNB, a Node B, an 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 transmission reception point (TRP), or some other suitable term. The base station 102 provides an access point to the EPC 160 or the core network 190 for the UE 104. Examples of UE 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., an MP3 player), a camera, a game console, a tablet device, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a health care device, an implant, a sensor / actuator, a display, or any other similar functional device. Some UEs 104 may be referred to as IoT devices (e.g., parking meters, gas pumps, ovens, vehicles, heart monitors, etc.). 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 communication 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.

[0044] Some wireless communication networks may include vehicle-based communication devices that can communicate and / or communicate with other devices from vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I) (e.g., from a vehicle-based communication device to a road infrastructure node, such as a roadside unit (RSU)), vehicle-to-network (V2N) (e.g., from a vehicle-based communication device to one or more network nodes, such as a base station), and / or a combination thereof, which communications may be collectively referred to as vehicle-to-everything (V2X) communications. V2X communications may include, for example, cellular V2X (CV2X) communications. Again, referring to Figure 1 In some aspects, a UE 104 (e.g., a transmitting vehicle user equipment (VUE) or other UE) may be configured to transmit a message directly to another UE 104. The communication may be based on V2V / V2X / V2I or other D2D communications, such as Proximity Services (ProSe), etc. Communications based on V2V, V2X, V2I, and / or D2D may also be transmitted and received by other transmitting and receiving devices, such as a roadside unit (RSU) 107, etc.

[0045] Aspects of the communication may be based on PC5 or sidelink communication, for example, as combined with Figure 2 Although the following description may provide examples regarding V2X / D2D communications in conjunction 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.

[0046] Refer again Figure 1 In some aspects, the wireless device may include a calibration component 198 configured to perform radio impairment calibration during periodic silence periods. For example, the UE 104 may include the calibration component. Although described in conjunction with the UE, the RSU 107 or other wireless devices that communicate based on V2X, V2V, and / or other D2D may include the calibration component 198. The calibration component may be configured to perform in conjunction with at least Fig. 9 and 10 The aspects described.

[0047] Figure 2Example diagrams 200 and 210 are illustrated, which show example time slot structures that can be used for wireless communication (e.g., for sidelink communication) between UE 104 and UE 104'. The time slot structure may be within a 4G or 5G / NR frame structure. Although the following description may focus on 4G, the concepts described herein may be applicable to other similar fields, such as 5G / NR, LTE, LTE-A, CDMA, GSM, and other wireless technologies. This is just an example, and other wireless communication technologies may have different frame structures and / or different channels. A frame (10ms) may be divided into 10 equally sized subframes (1ms). Each subframe may include one or more time slots. A subframe may also include a mini-time slot, which may include 7, 4, or 2 symbols. Each time slot may include 7 or 14 symbols, depending on the time slot configuration. For time slot configuration 0, each time slot may include 14 symbols, and for time slot configuration 1, each time slot may include 7 symbols. Diagram 200 illustrates a single time slot transmission, which may correspond to a 0.5 ms transmission time interval (TTI), for example. Diagram 210 illustrates example 2 time slot aggregation, for example, aggregation of two 0.5 ms TTIs. Diagram 200 illustrates a single RB, while diagram 210 illustrates N RBs. In diagram 210, the 10 RBs used for control are merely an example. The number of RBs may be different.

[0048] A resource grid may be used to represent the frame structure. Each time slot may include a resource block (RB) (also called a physical RB (PRB)) extending over 12 consecutive subcarriers. The resource grid is divided into a number of resource elements (REs). The number of bits carried by each RE depends on the modulation scheme. Figure 2 As illustrated in , some REs may include control information, for example, together with a demodulation RS (DMRS). Figure 2 It is also illustrated that the symbol(s) may include CSI-RS. Figure 2A symbol dedicated to DMRS or CSI-RS in indicates that the symbol includes DMRS or CSI-RS RE. Such a symbol may also include REs containing data. For example, if the number of ports of DMRS or CSI-RS is 1 and the comb-2 mode is used for DMRS / CSI-RS, half of the REs may include the RS, and the other half of the REs may include data. The CSI-RS resource may start at any symbol of the time slot and may occupy 1, 2, or 4 symbols, depending on the number of ports configured. The CSI-RS may be periodic, semi-persistent, or aperiodic (e.g., based on DCI triggering). For time / frequency tracking, the CSI-RS may be periodic or aperiodic. The CSI-RS may be transmitted in bursts of two or four symbols spread across one or two time slots. The control information may include sidelink control information (SCI). At least one symbol may be used for feedback, as described herein. The symbols before and / or after the feedback may be used to switch between data reception and feedback transmission. Although symbol 12 is illustrated as being used for data, it may instead be a gap symbol to enable turnaround for feedback in symbol 13. Another symbol (e.g., at the end of a slot) may be used as a gap. The gap enables the device to switch from operating as a transmitting device to preparing to operate as a receiving device (e.g., in a subsequent slot). As illustrated, data may be transmitted in the remaining REs. The data may include data messages as described herein. The location of any of the SCI, feedback, and LBT symbols may be the same as Figure 2 Different from the example illustrated in , multiple time slots can be grouped together. Figure 2 An example aggregation of two time slots is also illustrated. The number of time slots aggregated may also be greater than two. When time slots are aggregated, the symbols and / or gap symbols used for feedback may be different from the symbols and / or gap symbols used for feedback for a single time slot. Although feedback is not illustrated for this aggregation example, the symbol(s) in a multi-slot aggregation may also be allocated for feedback, as illustrated in the one time slot example.

[0049] Figure 3 3 is a block diagram of a first wireless communication device 310 in communication with a second wireless communication device 350, for example, via V2V / V2X / D2D communication. Device 310 may include a transmitting device that communicates with a receiving device (e.g., device 350) via V2V / V2X / D2D communication. The communication may be based on, for example, a side link. The transmitting device (e.g., device 310) may include a UE, an RSU, etc. The receiving device may include a UE, an RSU, etc. The packet 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 media access control (MAC) layer.

[0050] The transmit (TX) processor 316 and the receive (RX) processor 370 implement layer 1 functionality associated with various signal processing functions. Layer 1, including the physical (PHY) layer, may include error detection on the transport channel, forward error correction (FEC) encoding / decoding of the transport channel, interleaving, rate matching, mapping to the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. The TX processor 316 handles the mapping to the signal constellation 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 domain 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 generate multiple spatial streams. Channel estimates from channel estimator 374 can be used to determine coding and modulation schemes and for spatial processing. The channel estimates can be derived from reference signals and / or channel condition feedback transmitted by device 350. Each spatial stream can then be provided to a different antenna 320 via a separate transmitter 318TX. Each transmitter 318TX can modulate an RF carrier with a corresponding spatial stream for transmission.

[0051] At the device 350, each receiver 354RX receives a signal through its respective antenna 352. Each receiver 354RX recovers the information modulated onto the RF carrier and provides the information to a 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 can perform spatial processing on the information to recover any spatial stream destined for the device 350. If there are multiple spatial streams destined for the device 350, they can be combined into a single OFDM symbol stream by the RX processor 356. The RX processor 356 then transforms the OFDM symbol stream from the time domain to the frequency domain using a fast Fourier transform (FFT). The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, as well as the reference signal, are recovered and demodulated by determining the signal constellation point most likely transmitted by the device 310. These soft decisions can be based on the channel estimates calculated by the channel estimator 358. These soft decisions are then decoded and deinterleaved to recover the data and control signals originally transmitted on the physical channel by device 310. These data and control signals are then provided to controller / processor 359 which implements layer 3 and layer 2 functionality.

[0052] The controller / processor 359 may 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, packet reassembly, decryption, header decompression, and control signal processing between transport and logical channels. The controller / processor 359 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0053] Similar to the functionality described in conjunction with transmissions performed by device 310, the controller / processor 359 may provide RRC layer functionality associated with system information (e.g., MIB, SIB) capture, RRC connection, and measurement reporting; PDCP layer functionality associated with header compression / decompression, and security (encryption, decryption, integrity protection, integrity verification); RLC layer functionality associated with delivery of upper layer PDUs, error correction through ARQ, concatenation, segmentation and reassembly of RLC SDUs, resegmentation 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.

[0054] Channel estimates derived by a channel estimator 358 from a reference signal or feedback transmitted by the device 310 may be used by a 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 antennas 352 via separate transmitters 354TX. Each transmitter 354TX may modulate an RF carrier with a corresponding spatial stream for transmission.

[0055] The transmission is processed at device 310 in a manner similar to that described in conjunction with the receiver functionality at device 350. Each receiver 318RX receives a signal through its respective antenna 320. Each receiver 318RX recovers the information modulated onto the RF carrier and provides the information to a RX processor 370.

[0056] The controller / processor 375 may 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, packet reassembly, decryption, header decompression, control signal processing between transport and logical channels. The controller / processor 375 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0057] At least one of the TX processor 368, RX processor 356, or controller / processor 359 of device 350, or the TX processor 316, RX processor 370, or controller / processor 375 may be configured to perform a combination of Figure 1 In the aspects described in 198 , it can be configured to perform radio impairment calibration during periodic silence periods.

[0058] Figure 4 An example 400 of wireless communication between devices based on V2X / V2V / D2D communication is illustrated. The communication may be based on a combination of Figure 2 The time slot structure of various aspects described. For example, a transmitting UE 402 may transmit a transmission 414 (e.g., including a control channel and / or a corresponding data channel), which may be received by receiving UEs 404, 406, 408, 409. The control channel may include information for decoding the data channel, and may also be used by the receiving device to avoid interference by suppressing transmission on occupied resources during data transmission. The number of TTIs and RBs that the data transmission will occupy may be indicated in a control message from the transmitting device. In addition to being able to operate as a receiving device, UEs 402, 404, 406, 408, 409 may each be able to operate as a transmitting device. Therefore, UEs 406, 408 are illustrated as transmitting transmissions 416, 420. Transmissions 414, 416, 420 may be broadcast or multicast to nearby devices. For example, UE 402 may transmit communications intended to be received by other UEs within the range 401 of UE 402. Additionally / alternatively, the RSU 407 may receive communications from and / or transmit communications to the UEs 402 , 404 , 406 , 408 , 409 .

[0059] Any of the UEs 402, 404, 406, 408, 409 or RSU 407 may include a calibration component similar to that incorporated into the Figure 1 198 as described.

[0060] In some aspects, communications may be exchanged directly between UEs without infrastructure support. Such communications may include V2X (e.g., CV2X), V2V, and / or other D2D communications. Figure 4As described, the UE may transmit and receive direct communications and controls, for example, on PC5. Thus, this communication may be self-managed by these UEs without network assistance. As an example, CV2X Mode-4 may involve operations without infrastructure support. UEs involved in this communication may use a resource pool allocated for the communication. Semi-persistent scheduling (SPS) may be used to select and / or reserve resources for transmission by the UE. Control information (such as sidelink control information) may be transmitted on the PSCCH. Data (e.g., sidelink data) may be transmitted on the PSSCH. The V2X signal may vary between subframes, for example, based on different frequency allocations and different received signal powers for different subframes. For example, the V2X signal may vary in a random manner and may change in each subframe. This may be contrasted with other types of communications (such as LTE), which may have a more stable signal over time. Additionally, the V2X transceiver may transmit using a low duty cycle (e.g., a duty cycle of less than 3% or about 2%). The V2X transceiver may transmit only once every 100ms, 200ms, 300ms, and so on.

[0061] In order to correctly receive the signal, radio impairment calibration may be performed for the receiver. The transmission signal may be transmitted in burst mode by each UE communicating based on V2X, V2V, or other D2D communications. As an example, a vehicle may transmit communications in burst mode, and a receiving device (e.g., a receiving UE, a vehicle, an RSU, etc.) may similarly operate in burst mode to receive the communication. Therefore, there may not be a continuous loop operating on the receiver side of the UE, for example, on a subframe basis. As an example, V2X communications may employ fast automatic gain control (AGC) to adjust the gain at the beginning of each subframe in less than one symbol of time.

[0062] Direct current (DC) tracking performed at a receiver may depend on the gain of the receiver. DC tracking may be performed according to the gain state of the receiver, for example, when the gain is stable. A reading of the DC tracking loop may be taken every subframe (for example, at the end of a subframe).

[0063] The receiver may perform calibration for DC, in-phase quadrature (IQ) imbalance calibration, etc. Calibration may be performed per subframe for the relevant AGC gain state (GS) being used by the receiver. When the receiver uses an infrequently used gain state, the receiver may suffer from a high DC level. A high DC level may occur due to DC drift, for example, as a result of temperature change. Similar effects may occur for IQ imbalance or timing skew. If calibration is not performed within a certain period of time, these calibration parameters may become obsolete. Removal of DC on the relevant resource allocation may affect the parameters used in the receiver calibration. As an example, DC removal may affect the AGC decision. Therefore, the removal of inaccurate DC may result in the selection of an incorrect gain state, which may degrade the sensitivity of the receiver and result in a reduced signal-to-noise ratio (SNR). Even if the AGC selection is appropriate, the removal of the inaccurate DC may also affect the SNR determination under a specific gain state. Therefore, the removal of inaccurate DC may result in a reduced SNR, even if the appropriate gain state is selected.

[0064] If the DC estimation is done in the presence of a strong signal with an assignment at the DC range, the DC estimate can be affected and corrupted. It may therefore be helpful to verify that the received signal power is below a predefined threshold. Performing a DC calibration during a silent period virtually eliminates the chance of a strong signal being present when the calibration is performed, thereby significantly improving the efficiency of the calibration. There are rare situations where an interfering signal, such as a Dedicated Short Range Communication (DSRC) signal, may be close to the V2X signal and may have some impact on the measurement.

[0065] Figure 5 An example 500 of automatic gain control for a receiver (eg, a receiver for V2X communication, V2V communication, sidelink communication, D2D communication, etc.) is illustrated. Figure 5 This is merely an example, and automatic gain control may be applied using different components and in different ways. Initially, a fast AGC may be used to adjust the gain at the beginning of each subframe. Fast AGC may refer to an AGC that is performed in a time less than one symbol. The AGC may start by using an initial gain setting and may select a final gain setting to converge on a wideband signal energy estimate. The AGC decision for a converged gain setting may be based on a wideband signal energy estimate.

[0066] For example, Figure 5As illustrated in , a signal may be received by a receiver 504 (or transceiver) via an antenna 502. Gain may be applied to each of the components of the receiver 504. The receiver may include one or more LNAs. The receiver 504 may include a baseband receiver (BBRx) and / or an analog-to-digital converter (ADC) component 506. The ADC component 506 may output unsigned data. The processing component 505 may include a mapper 508 that receives unsigned data from the ADC component 506 and may convert the format from an unsigned format to a signed format. After processing at the mapper 508, a wideband signal energy estimation component 510 may generate an estimate of the wideband signal energy. The estimate of the wideband signal energy may be provided to an AGC processing and control component 512. The AGC processing and control component 512 may select an AGC gain state to be applied (e.g., applied at the receiver 504). The signal may be processed by various filters, such as any one of (all) decimation filters 514, variable sampling rate converters (VSRCs), and decimation filters 516, etc. After filtering, component 518 may perform DC offset estimation and / or digital elimination. For example, component 518 may estimate the DC in the received signal. The estimate may be provided to wideband signal energy estimation component 510 for use in estimating wideband signal energy, for example, after eliminating or otherwise removing the estimated DC from the signal. Therefore, the estimate of the wideband signal energy for selecting the AGC gain state to be applied at the receiver may eliminate the DC based on the DC estimate. Additional processing of the signal may be provided (e.g., by component 520). Since the DC offset generated at the receiver mixer output may be subtracted from the wideband signal energy estimate for selecting gain, a more accurate DC estimate may improve the selection and application of the gain state. The DC offset estimation and elimination for the active receiver AGC gain state affect the AGC decision, receiver sensitivity, and SNR. The DC offset estimate may be affected by the presence of a wideband signal.

[0067] Figure 6 An example 600 of components of a receiver 604 that may experience leakage from a local oscillator (LO) is illustrated. As an example, if the leakage from the LO input to the downconverter is added to the wideband signal energy, the leakage may be too high and if the leakage is not properly cancelled, it may result in an erroneous energy estimate for the wideband received signal. Therefore, the AGC gain selection may be incorrect.

[0068] The various aspects presented herein provide improved RF calibration. Various aspects may facilitate burst transmissions, which may not have multiple opportunities to perform calibration of transmitter gain and output power. Similarly, there may be limited opportunities for loopback calibration. In loopback mode, calibration may be performed to adjust for IQ imbalance or timing skew. Loopback calibration may include determining LO leakage and estimating a transmission image (e.g., a transmission image may be a folded baseband converted by LO next to the signal), which limits the transmitter error vector magnitude (EVM) / SNR. As an example, the CV2X output power tolerance may be less than the output power tolerance of other RATs. For example, Table 1 illustrates the absolute power tolerance under normal and extreme conditions for LTE. Table 2 illustrates the absolute power tolerance under normal and extreme conditions for VC2X. Smaller output power tolerance increases the benefits of improved calibration for transmitter gain control.

[0069] Table 1

[0070]

[0071] Table 2

[0072]

[0073]

[0074] Various aspects presented herein may include using the time reserved for a silent period, a blanking mode, and / or a silent mode to perform calibration. As an example, a CV2X transceiver may be active on the first thirteen symbols of a time slot (e.g., symbol 0 to symbol 12). At symbol 13 (e.g., at the last symbol of a time slot), the CV2X transceiver observes a silent period. Observing the silent period may include operating a transmitter in a blanking mode without requiring a receiver to operate. The symbol may be a reserved symbol, wherein each device operating using CV2X observes the silent period and suppresses transmission. For example, the devices may suppress transmissions above a defined power level. Since the devices suppress transmissions to other devices during the symbol, the devices do not need to attempt to receive communications during the symbol. The example of a single symbol is merely illustrative of the concept. The silent period may extend to any amount of time. The silent period may correspond to (s) silent symbol(s), (s) silent subframe(s), and the like. The silence period may correspond to masked subframe(s) or symbol(s).Also, although CV2X is used to illustrate the concept, aspects may also be applicable to silence periods based on another RAT.

[0075] To improve calibration, for example, for burst transmissions, the wireless device may use a silent period (e.g., symbol 13 in CV2X) for performing calibration. The calibration may include calibration for untrained gain states. The calibration may include calibration for less frequently trained gain states from a plurality of gain states. The calibration may include measurement of a DC level estimated by a DC tracking loop for each gain state.

[0076] By performing the calibration during a silent period, the wireless device may be able to perform calibration for a gain state that has not been used for a relatively long time (e.g., compared to when other gain states have been used). Such a gain state that was last calibrated at a later point than other gain states may suffer from added DC drift, RSB drift, etc. Using a silent period to perform calibration improves the accuracy of the calibration without the influence of received signals that may cause receiver saturation or residual calibration errors. The calibration may also be improved by fewer interruptions from other signals.

[0077] Figure 7An example 700 of a symbol set for a receiver is illustrated. The receiver may operate in a normal mode from symbol 0 to symbol 12. Then, at symbol 13, the receiver may observe a silent period. The period during which the receiver operates in this mode may be referred to as a silent period or a mute period. Since the period in this example is a single symbol, the symbol may be referred to as a silent symbol or a mute symbol. During symbol 13, the receiver may perform calibration, for example, based on any one of in-phase quadrature (IQ) imbalance calibration, DC calibration, timing skew calibration, clutter calibration, loopback calibration, etc. The clutter calibration may include calibration for continuous wave clutter and / or other unmodulated clutter. The receiver may perform calibration each time a silent period occurs. For example, the receiver may perform calibration in each symbol 13. At each symbol 13, the receiver may select a gain state that is less trained than other gain states to be calibrated. For example, in order to perform DC calibration for an untrained gain state (e.g., gain state Gi) at symbol 13, the receiver may set the receiver gain to gain state Gi during symbol 13 and may perform DC calibration. As part of the calibration, the receiver may verify that a considerable amount of signal power is not received during symbol 13. A considerable amount of signal power may correspond to an amount that may affect the DC estimate. For example, the receiver may determine whether the received signal power is above a threshold power level. If the received signal power is above the threshold power level, the receiver may discard the measurement. The threshold may depend on the receiver gain state. As an example, if the expected noise power is -43dBm, if the received signal power is measured to be above -38dBm during the silent symbol, the measurement may be discarded. The threshold may differ from an expected noise power of less than 10dBm, less than 7dBm, less than 5dBm, or even lower. In an example, the threshold level may be application specific. A received signal power above the threshold may indicate a signal from a jammer or DSRC. If the received signal power is below the threshold, the receiver may update the DC measurement table for the gain state Gi as part of the calibration process. At the next symbol 13, a different untrained gain state may be selected by the receiver for calibration, and the DC measurement for that gain state may be added to the DC measurement table. Thus, the receiver may continuously update the DC measurement table by performing DC measurements for gain states that are less trained or have older DC measurements.

[0078] Figure 7Also illustrated is an example 710 of a symbol set for a transmitter. A wireless device may sometimes operate as a receiver and at other times as a transmitter. Thus, examples 700, 710 may be applied to a single wireless device. The transmitter may operate in a normal mode from symbol 0 to symbol 12. Then, at symbol 13, the transmitter may observe a silent period, as described in conjunction with example 710. During symbol 13, the wireless device may change from operating as a transmitter to operating as a receiver in order to perform calibration, for example, calibration based on any one of DC offset calibration, IQ imbalance, timing skew calibration, clutter calibration, loopback calibration, etc. The clutter calibration may include calibration for continuous wave clutter and / or other unmodulated clutter. Each time a silent period occurs, the transmitter may change to receive in order to perform calibration. As described in conjunction with receiver example 700, the transmitter may select an untrained gain state, or a gain state with an older DC measurement, and may use the selected gain state to perform DC calibration. After verifying that the received signal power is not above the threshold, the wireless device may update the DC measurement table by adding the DC measurement for the selected gain state as part of the calibration process based on the DC tracking loop readings.

[0079] By performing measurements during silent periods, the accuracy of calibration can be improved and calibration can be performed with minimal interruption to incoming signals. By improving the accuracy of measurements and maintaining a more accurate DC measurement table, the wireless device can improve burst mode communications. By calibrating receiver gains that have not been used for a longer amount of time (e.g., with respect to parameters such as DC offset, IQ imbalance), the relevant parameters and calibration tables can be maintained in a more current, more accurate manner. Then, when the gain is used in an active receiver (e.g., during symbols 0 to 12), these relevant parameters will be up to date and the receiver is less likely to suffer performance degradation. The silent period may include a silent reception period, for example, as described in conjunction with example 700. The silent period may include a silent transmission period, for example, as described below in conjunction with example 710.

[0080] As another example, the wireless device may not switch to reception during symbol 13 and may instead remain in transmit mode in order to perform transmit calibration. For example, the wireless device may use a silent period to perform loopback calibration. For example, the wireless device may use a loopback mode to transmit a signal at a low transmit power and use a receiver at the wireless device to receive the signal. The wireless device may use a transmit power below a threshold level in order to avoid affecting other wireless devices that are observing the silent period. As an example, the wireless device may use a transmit power below -50 dBm (EIRP at the antenna port) to transmit. Additionally and / or alternatively, the wireless device may perform transmission during the silent period at a level not exceeding that allowed by the standard (below -50 dBm). For example, the power amplifier may be in a closed state for the transmission. By measuring the signal in a loopback mode without power amplification, the wireless device may perform a measurement of the residual sideband signal level transmitted by the receiver in synchronization with the transmission. The transmission may be performed for calibration without exceeding the power limit for the silent period. If shutting down the power amplification is not sufficient, the pre-power amplified transmit portion of the power may be attenuated to allow the power to fall below the limit.

[0081] Figure 8 An example communication flow 800 between a first UE 802 and a second UE 804 is illustrated. The communication may be based on V2X communication, V2V communication, other D2D communication, etc., such as in conjunction with Figure 4As described. As an example, the communication may be based on CV2X. Both UE 802 and UE 804 may communicate during a first time period and may observe a silent period. For example, at 801, UE 802 may communicate as a transmitter by transmitting communication 806 to UE 804. At 819, UE 804 may communicate by receiving communication 806 during a first time period. For example, UE 804 may transmit communication 806 during symbols 0 to 12 of a subframe. During a silent period (e.g., symbol 13), UE 802 may observe a silent period at 803. Similarly, UE 804 may observe a silent period at 821. During the silent period, UE 802 may suppress transmissions above a threshold power level, and UE 804 may not need to receive communications from other UEs. UE 802 may use the silent period to perform receiver calibration or perform transmitter calibration. UE 804 may use the silent period to perform receiver calibration. For example, at 805, UE 802 may change from a transmit mode to a receive mode in order to perform receiver calibration during a silent period. At 807, UE 802 may select a gain state, for example, a gain state that is not trained or has an older measurement. At 809, UE 802 may determine whether the measured signal power is higher than a level that may indicate an interferer or DSRC. If the measured signal power is higher than the level, UE 802 may discard the measurement. Otherwise, at 811, UE 802 may add a DC measurement for the selected gain state to a DC measurement table. The DC measurement table may be used, for example, when the UE returns to communication during an active period and selects a gain state for which a measurement has been performed. Similarly, UE 804 may observe a silent period at 821; select a gain state at 823; and perform calibration measurements. At 825, UE 804 may determine whether the measured signal power is higher than the level, and UE 804 may discard the measurement. Otherwise, at 827, UE 804 may add the DC measurement for the selected gain state to the DC measurement table. UE 802 and UE 804 may, for example, return to communication during the active period at 817, 829, respectively. For example, UE 802 and 804 may continue to exchange communication 810 during the active period. The communication may be transmitted by UE 802 and received by UE 804, or may be transmitted by UE 804 and received by UE 802. In the active period, the UE may apply the updated measurement from the calibration performed during the silent period. As an example, these UEs may return to exchange communication at symbol 0 after symbol 13. At each symbol 13, these UEs may continue to perform calibration.

[0082] During the silent period, UE 802 may perform transmitter calibration, e.g., instead of receiver calibration described in conjunction with 805-811. For example, at 813, UE 802 may transmit signal 808 using low transmit power (e.g., below a threshold) and without power amplification. While transmitting signal 808, UE 802 may use a receiver at 815 to receive signal 808 and perform transmit calibration measurements. The calibration measurements may assist in determining loopback calibration. Loopback calibration may include IQ imbalance calibration or timing skew calibration performed when the UE is in loopback mode. For example, calibration measurements may be performed in loopback mode. After performing calibration measurements, UE 802 may return to communication during an active period at 817.

[0083] Fig. 9 900 is a flow chart of a method of wireless communication. The method may be performed by a wireless device or a component in a wireless device (e.g., UE 104, 402, 404, 406, 408, 802, 804; RSU 107, 407; device 310, 350; equipment 1002 / 1002'; processing system 1114, which may include memory and which may be an entire wireless device (e.g., an entire UE, an RSU, etc.) or a component in a wireless device (e.g., a component in a UE, an RSU, etc.)). Optional aspects are illustrated with dashed lines. The method improves calibration, and particularly calibration for burst mode communications, so that the device can transmit and receive communications more accurately.

[0084] At 902, a wireless device communicates with a second wireless device during an active period. The wireless device may communicate with the second wireless device based on at least one of V2X communication, V2V communication, or other D2D communication. In one example, the device may communicate with the second wireless device based on CV2X communication. The communication may be performed, for example, by a communication component 1008 of the equipment 1002. The communication may include receiving a communication from a second wireless device (e.g., wireless device 1050) via a receiving component 1004 and / or transmitting a communication to the wireless device 1050 via a transmitting component 1006.

[0085] At 904, the wireless device may suppress transmissions above a threshold transmit power during the silent period and may not need to receive communications. The periodic silent period may include at least one symbol of the subframe. In some examples, the periodic silent period may include the last symbol of the subframe. In the example described with respect to CV2X, the silent period may include symbol 13, and the active period may correspond to symbol 0 to symbol 12. In other examples, the silent period may correspond to a different amount of time observed by the wireless device. For example, the communication component 1008 of the equipment 1002 may suppress transmissions above a threshold transmit power during the silent period.

[0086] At 906, the wireless device performs radio impairment calibration during the periodic silence period. Radio impairment calibration corresponds to a process for identifying signal components that are not part of the expected transmission signal. These unexpected signal components may be introduced by the radio hardware of the transmitter or receiver. Radio impairment calibration may include measuring any unexpected signal components within the signal and removing the measured non-target signal components from the signal. Removing or eliminating the unexpected signal components from the signal provides a signal without impairment. The removal or elimination of the unexpected signal components may be performed by an analog block of a signal processing system, a digital block of a signal processing system, or a combination of both. For example, at least calibration component 1012 in equipment 1002 may perform calibration. Radio impairment calibration may include receiving calibration and / or transmitting calibration. The radio impairment calibration may include DC offset calibration, IQ imbalance, timing skew calibration, clutter calibration, loopback calibration, and the like. Clutter calibration may include calibration for continuous wave clutter and / or other unmodulated clutter.

[0087] For example, the radio impairment calibration may include receiver calibration. As illustrated at 910, as part of performing the calibration, the wireless device may select a gain state to calibrate. The selection may be performed, for example, by a gain state component 1014 of the equipment 1002. The wireless device may select an untrained gain state or an older gain state with older measurements than another gain state. By selecting a gain state with older measurements, the wireless device may maintain more current calibration measurements.

[0088] At 912, the wireless device may perform a DC measurement for the selected gain state during the periodic silence period. For example, the gain state selected by the equipment gain state component 1014 may be applied to the receiving component 1004, and the measurement may be performed by the measuring component 1016. The radio impairment calibration may include at least one of a DC offset calibration and / or an IQ imbalance calibration. In other examples, the impairment calibration may include a loopback calibration for transmit calibration.

[0089] At 916, the wireless device may update the DC measurement for the selected gain state. The update may be performed, for example, by an update component 1020 of the apparatus 1002. For example, the UE may maintain a table of DC measurements for multiple possible gain states. By performing calibration measurements during silent periods, the wireless device may update the table without interfering with communications and may obtain more accurate measurements. Additionally, by selecting untrained / less frequently trained gain states, the wireless device may help ensure that the DC measurement is accurate when a particular gain state is needed for active communications.

[0090] At 914, before updating the DC measurement, the wireless device may determine whether the measurement includes a signal power above a threshold, wherein when the signal power is not above the threshold, the DC measurement for the selected gain state is updated. If the signal power is above the threshold, the wireless device may discard the measurement at 918. Otherwise, the wireless device may continue to 916 and update the DC measurement for the selected gain state. The determination may be performed, for example, by a determining component 1018 of the apparatus 1002.

[0091] The wireless device may operate in a receive state prior to the silent period, for example, as combined with Figure 7 In another example, the wireless device may operate in a transmit state prior to the silent period, for example, as described in conjunction with Figure 7 As described in example 710 in . When the wireless device transmits during the active period, at 908, the wireless device can switch from the transmit mode to the receive mode to perform radio impairment calibration, such as receiver calibration, during the periodic silent period. For example, the calibration component 1012 of the equipment 1002 can perform the switch to the receive mode to perform the calibration.

[0092] In another example, the wireless device may perform transmit calibration during the silent period. For example, the wireless device may transmit during the active period at 902. The transmitting may be performed, for example, by a transmitting component, for example, based on instructions from a calibration component 1012 of the equipment 1002. At 920, the wireless device may transmit a transmission below a transmit power level threshold during the silent period, for example, without power amplification. By transmitting a signal below the transmit power level and without power amplification, the wireless device may observe the silent period and may avoid interfering with the operation of other wireless devices observing the silent period.

[0093] At 922, the wireless device can measure the transmission using a receiver of the wireless device as part of performing radio impairment calibration. For example, the measurement can be performed by a measurement component 1016 of the equipment 1002. Thus, the wireless device can perform calibration using a loopback mode. For example, the radio impairment calibration can include a loopback calibration.

[0094] Fig.101 is a conceptual data flow diagram 1000 illustrating the data flow between different devices / components in an example equipment 1002. The equipment may be a wireless device or a component of a wireless device. For example, the equipment may include a UE or a component of a UE. In other examples, the equipment may include an RSU or a component of an RSU. In other examples, the equipment may include wireless device communications based on V2X, V2V, or other D2D communications. The equipment includes a receiving component 1004 that receives wireless communications (e.g., directly from a wireless device 1050) and a transmitting component 1006 that transmits directly to the wireless device 1050. Although the wireless device 1050 is illustrated as a UE, the second wireless device may include an RSU, etc. The equipment may include a communication component 1008 configured to communicate with the wireless device 1050 during an active period. The equipment may transmit or receive during an active period and may suppress transmissions above a threshold power level during a silent period. The equipment may include a calibration component 1012 configured to perform radio impairment calibration during periodic silent periods. The equipment may include a gain state component 1014 configured to select a gain state to be calibrated. The equipment may include a measurement component 1016 configured to perform a measurement of DC for the selected gain state during a periodic silent period. The equipment may be an update component 1020 configured to update the DC measurement for the selected gain state. The equipment may include a determination component 1018, which is configured to determine whether the measurement includes a signal power above a threshold, wherein when the signal power is not above the threshold, the DC measurement for the selected gain state is updated via the update component 1020. The measurement component, the determination component, and / or the update component may be configured to discard the measurement when the measurement includes a signal power above the threshold. The equipment may transmit during an active period, and the communication component 1008 may be configured to switch from a transmission mode (e.g., using the transmission component 1006) to a reception mode (e.g., using the reception component 1004) to perform radio impairment calibration during the periodic silent period. Transmitting component 1006 can be configured to transmit a transmission below a transmit power level threshold during a quiet period, and measuring component 1016 can be configured to measure the transmission using receiving component 1004 as part of performing radio impairment calibration.

[0095] The equipment may include performing Figure 8 and 9 The additional components of each box of the algorithm in the preceding flowchart. Thus, Figure 8 and 9Each block in the aforementioned flow chart of can be performed by a component and the equipment may include one or more of these components. These components can be one or more hardware components specially configured to execute the process / algorithm, implemented by a processor configured to execute the process / algorithm, stored in a computer-readable medium for implementation by a processor, or some combination thereof.

[0096] Fig.11 1 is a diagram 1100 illustrating an example of a hardware implementation of an apparatus 1002' employing a processing system 1114. The processing system 1114 may be implemented with a bus architecture generally represented by a bus 1124. Depending on the specific application of the processing system 1114 and the overall design constraints, the bus 1124 may include any number of interconnecting buses and bridges. The bus 1124 links together various circuits, including one or more processors and / or hardware components (represented by the processor 1104, components 1004, 1006, 1008, 1012, 1014, 1016, 1018, 1020, and computer readable medium / memory 1106). The bus 1124 may also link various other circuits, such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described further.

[0097] The processing system 1114 may be coupled to the transceiver 1110. The transceiver 1110 is coupled to one or more antennas 1120. The transceiver 1110 provides equipment for communicating with various other devices over a transmission medium. The transceiver 1110 receives signals from the one or more antennas 1120, extracts information from the received signals, and provides the extracted information to the processing system 1114 (specifically, the receiving component 1004). In addition, the transceiver 1110 receives information from the processing system 1114 (specifically, the transmitting component 1006) and generates signals to be applied to the one or more antennas 1120 based on the received information. The processing system 1114 includes a processor 1104 coupled to a computer-readable medium / memory 1106. The processor 1104 is responsible for general processing, including the execution of software stored on the computer-readable medium / memory 1106. The software, when executed by the processor 1104, causes the processing system 1114 to perform the various functions described above for any particular device. The computer-readable medium / memory 1106 may also be used to store data manipulated by the processor 1104 when executing software. The processing system 1114 further includes at least one of the components 1004, 1006, 1008, 1012, 1014, 1016, 1018, 1020. These components may be software components running in the processor 1104, software components resident / stored in the computer-readable medium / memory 1106, one or more hardware components coupled to the processor 1104, or some combination thereof. The processing system 1114 may be a component of the device 310 or the device 350 and may include the memory 376, 360 and / or at least one of the following: the TX processor 316, 368, the RX processor 370, 356, and the controller / processor 375, 359. Alternatively, the processing system 1114 may be the entire UE (e.g., see Figure 3 device 310 or 350).

[0098] In one configuration, an apparatus 1002 / 1002' for wireless communication includes means for communicating with a second wireless device during an active period and means for performing radio impairment calibration during a periodic silent period. The apparatus may further include means for selecting a gain state to be calibrated, means for performing a DC measurement for the selected gain state during the periodic silent period, and means for updating the DC measurement for the selected gain state. The apparatus may include means for determining whether a measurement includes a signal power above a threshold, wherein when the signal power is not above the threshold, the DC measurement for the selected gain state is updated; and means for discarding the measurement when the measurement includes a signal power above the threshold. The apparatus may transmit during an active period, and may further include means for switching from a transmit mode to a receive mode in order to perform radio impairment calibration during a periodic silent period. The apparatus may include means for transmitting a transmission below a transmit power level threshold during a silent period and means for measuring the transmission using a receiver of a wireless device as part of performing radio impairment calibration. The aforementioned means may be one or more of the aforementioned components of the apparatus 1002 and / or the processing system 1114 of the apparatus 1002' configured to perform the functions recited by the aforementioned means. As described above, the processing system 1114 may include the TX processors 316, 368, the RX processors 370, 356, and the controllers / processors 375, 359. Thus, in one configuration, the aforementioned means may be the TX processors 316, 368, the RX processors 370, 356, and the controllers / processors 375, 359 configured to perform the functions recited by the aforementioned means.

[0099] It should be understood that the specific order or hierarchy of each box in the disclosed process / flowchart is an illustration of an example approach. It should be understood that the specific order or hierarchy of each box in these process / flowcharts can be rearranged based on design preferences. In addition, some boxes can be combined or omitted. The attached method claims present the elements of various boxes in an exemplary order and are not meant to be limited to the specific order or hierarchy presented.

[0100] The following examples are merely illustrative, and aspects thereof may be combined with aspects of other examples or teachings described herein without limitation.

[0101] Example 1 is a method of wireless communication at a first device, the method comprising: communicating with a second wireless device during an active period; and performing radio impairment calibration during a periodic silent period.

[0102] In Example 3, the method of Example 1 further includes the periodic silence period including at least one symbol of the subframe.

[0103] In Example 3, the method of Example 1 or Example 2 further includes the periodic silence period including a last symbol of a subframe.

[0104] In Example 4, the method of Example 1 or Example 3 further includes the first wireless device communicating with the second wireless device based on at least one of V2X, V2V, or other D2D communications.

[0105] In Example 5, the method of any one of Examples 1-4 further includes the radio impairment calibration comprising at least one of a DC offset calibration or an in-phase quadrature (IQ) imbalance calibration.

[0106] In Example 6, the method of any one of Examples 1-5 further includes: selecting a gain state to be calibrated; performing a DC measurement for the selected gain state during the periodic silent period; and updating the DC measurement for the selected gain state.

[0107] In Example 7, the method of any one of Examples 1-6 further comprises the first wireless device selecting an untrained gain state or an older gain state having older measurements than another gain state.

[0108] In Example 8, the method of any one of Examples 1-7 further includes: determining whether the measurement includes a signal power above a threshold, wherein when the signal power is not above the threshold, the DC measurement for the selected gain state is updated; and discarding the measurement when the measurement includes the signal power above the threshold.

[0109] In Example 9, the method of any one of Examples 1-8 further includes the first wireless device transmitting during the active period, and the method further includes switching from a transmit mode to a receive mode to perform the radio impairment calibration during the periodic silence period.

[0110] In Example 10, the method of any of Examples 1-9 further includes the first wireless device transmitting during the active period, and the method further includes: transmitting a transmission below a transmit power level threshold during the silent period; and measuring the transmission using a receiver of the first wireless device as part of performing the radio impairment calibration.

[0111] In Example 11, the method of any one of Examples 1-10 further includes the radio impairment calibration comprising a loopback calibration.

[0112] In Example 12, a device is provided that includes one or more processors and one or more memories in electronic communication with the one or more processors, the one or more memories storing instructions that can be executed by the one or more processors to cause the system or device to implement a method as in any of Examples 1-11.

[0113] Example 13 is a system or apparatus comprising means for implementing a method as in any one of Examples 1-11 or implementing an apparatus as in any one of Examples 1-11.

[0114] Example 14 is a non-transitory computer-readable medium storing instructions executable by one or more processors, the instructions causing the one or more processors to implement the method as in any of Examples 1-11.

[0115] 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 easily understood by those skilled in the art, and the universal principles defined in this article can be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown in this article, but should be granted the full scope consistent with the claims in language, wherein the singular reference of the elements is not intended to represent "there is and only one", but "one or more", unless otherwise stated. The wording "exemplary" is used in this article to mean "used as an example, instance, or explanation". Any aspect described as "exemplary" herein does not have to be interpreted as being superior to or superior to other aspects. Unless otherwise stated, the term "some / certain" 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 multiple A, multiple B or multiple 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, wherein any such combination may include one or more members of A, B, or C. All structural and functional equivalents of the elements of the various aspects described throughout this disclosure that are currently or hereafter known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be covered by the claims. In addition, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is explicitly stated in the claims. The terms "module," "mechanism," "element," "device," and the like may not be a substitute for the term "means." Thus, no claim element should be interpreted as a means-plus-function unless the element is explicitly stated using the phrase "means for..."

Claims

1. A method of wireless communication at a first wireless device, comprising: transmitting or receiving sidelink communications with a second wireless device during the active period; as well as At least one of a direct current (DC) offset calibration or an in-phase or quadrature (IQ) imbalance calibration is performed for the sidelink communication during a periodic silent period for the sidelink communication.

2. The method of claim 1, wherein the periodic silence period comprises at least one symbol of a subframe.

3. The method of claim 1, wherein the periodic silence period includes at least a last symbol of a subframe. 4 . The method of claim 1 , wherein the first wireless device communicates with the second wireless device based on at least one of vehicle-to-vehicle (V2X) communication, vehicle-to-vehicle (V2V) communication, or other device-to-device (D2D) communication.

5. The method of claim 1, further comprising: selecting a gain state to be calibrated during the periodic silence period; performing a measurement of direct current DC for the selected gain state during the periodic silent period; as well as Updates the DC measurement for the selected gain state.

6. The method of claim 5, wherein selecting the gain state to be calibrated during the periodic silence period comprises selecting an untrained gain state to be calibrated during the periodic silence period.

7. The method of claim 5, wherein the DC measurement for the selected gain state is updated when the signal power is less than or equal to a threshold, the method further comprising: The measurement is discarded when the measurement includes the signal power above the threshold.

8. The method of claim 5, wherein selecting the gain state to be calibrated during the periodic silence period comprises selecting the gain state based on a time since the gain state was last measured.

9. The method of claim 8, wherein selecting the gain state to be calibrated during the periodic silence period comprises selecting a first gain state having an older measurement than a second gain state.

10. The method of claim 1, wherein the first wireless device transmits during the active period, the method further comprising: Switching from a transmit mode to a receive mode prior to performing at least one of the DC offset calibration or the IQ imbalance calibration during the periodic silence period.

11. The method of claim 10, wherein the first wireless device switches from the transmit mode to the receive mode before performing the DC offset calibration during the periodic silence period.

12. The method of claim 10, wherein the first wireless device switches from the transmit mode to the receive mode before performing the IQ imbalance calibration during the periodic silence period.

13. The method of claim 1, wherein the first wireless device transmits during the active period, the method further comprising: transmitting, during said periodic silence periods, transmissions below a transmit power level threshold; as well as The transmission is measured using a receiver of the first wireless device as part of performing the at least one of the DC offset calibration or the IQ imbalance calibration.

14. The method of claim 13, wherein the first wireless device measures the transmission using the receiver of the first wireless device as part of performing the DC offset calibration.

15. The method of claim 13, wherein the first wireless device measures the transmission using the receiver of the first wireless device as part of performing the IQ imbalance calibration.

16. The method of claim 1, wherein the at least one of the DC offset calibration or the IQ imbalance calibration comprises a loopback calibration.

17. The method of claim 16, wherein the DC offset calibration comprises the loopback calibration. The method of claim 16 , wherein the IQ imbalance calibration comprises the loopback calibration.

19. The method of claim 1, wherein the first wireless device is a first UE and the second wireless device is a second UE.

20. The method of claim 1, further comprising: The sidelink communication is transmitted or received after the periodic silence period based on the at least one of the DC offset calibration or the IQ imbalance calibration performed during the periodic silence period.

21. The method of claim 1, wherein transmitting or receiving the sidelink communication with the second wireless device during the active period comprises transmitting the sidelink communication with the second wireless device during the active period.

22. The method of claim 1, wherein transmitting or receiving the sidelink communication with the second wireless device during the active period comprises receiving the sidelink communication with the second wireless device during the active period.

23. The method of claim 1, wherein the first wireless device performs the DC offset calibration for the sidelink communication during the periodic silence period for the sidelink communication.

24. The method of claim 1, wherein the first wireless device performs the IQ imbalance calibration for the sidelink communication during the periodic silence period for the sidelink communication.

25. An apparatus for wireless communication at a first wireless device, comprising: Memory; as well as at least one processor coupled to the memory, the at least one processor configured to: transmitting or receiving sidelink communications with a second wireless device during the active period; as well as At least one of a direct current (DC) offset calibration or an in-phase or quadrature (IQ) imbalance calibration is performed for the sidelink communication during a periodic silent period for the sidelink communication.

26. The apparatus of claim 25, wherein the periodic silence period comprises at least one symbol of a subframe.

27. The apparatus of claim 25, wherein the periodic silence period includes a last symbol of a subframe.

28. The apparatus of claim 25, wherein the first wireless device communicates with the second wireless device based on at least one of vehicle-to-vehicle (V2X) communication, vehicle-to-vehicle (V2V) communication, or other device-to-device (D2D) communication.

29. The apparatus of claim 25, further comprising: At least one antenna is coupled to the at least one processor.

30. The apparatus of claim 25, wherein the at least one processor is further configured to: The sidelink communication is transmitted or received after the periodic silence period based on the at least one of the DC offset calibration or the IQ imbalance calibration performed during the periodic silence period.

31. The apparatus of claim 25, wherein the at least one processor is configured to transmit the sidelink communication with the second wireless device during the active period.

32. The apparatus of claim 25, wherein the at least one processor is configured to receive the sidelink communication with the second wireless device during the active period.

33. The apparatus of claim 25, wherein the at least one processor is configured to perform the DC offset calibration for the sidelink communication during the periodic silence period for the sidelink communication.

34. The apparatus of claim 25, wherein the at least one processor is configured to perform the IQ imbalance calibration for the sidelink communication during the periodic silence period for the sidelink communication.

35. The apparatus of claim 25, wherein the at least one processor is further configured to: selecting a gain state to be calibrated during the periodic silence period; performing a measurement of direct current DC for the selected gain state during the periodic silent periods; and Updates the DC measurement for the selected gain state.

36. The apparatus of claim 35, wherein to select the gain state to be calibrated during the periodic silence period, the at least one processor is configured to select an untrained gain state or an older gain state having older measurements than another gain state.

37. The apparatus of claim 35, wherein the at least one processor is further configured to: updating the DC measurement for the selected gain state when the signal power is less than or equal to a threshold; and The measurement is discarded when the measurement includes the signal power above the threshold.

38. The apparatus of claim 35, wherein to select the gain state to be calibrated during the periodic silence period, the at least one processor is configured to select the gain state based on a time since the gain state was last measured.

39. The apparatus of claim 38, wherein to select the gain state to be calibrated during the periodic silence period, the at least one processor is configured to select a first gain state having an older measurement than a second gain state.

40. The apparatus of claim 25, wherein the at least one processor is further configured to: Switching from a transmit mode to a receive mode for the active period in order to perform the at least one of the DC offset calibration or the IQ imbalance calibration during the periodic silent period.

41. The apparatus of claim 40, wherein the at least one processor is configured to switch from the transmit mode to the receive mode prior to the DC offset calibration during the periodic silence period.

42. The apparatus of claim 40, wherein the at least one processor is configured to switch from the transmit mode to the receive mode prior to the IQ imbalance calibration during the periodic silence period.

43. The apparatus of claim 25, wherein the at least one processor is further configured to: transmitting, during the periodic silence periods, transmissions below a transmit power level threshold; and The transmission is measured using a receiver of the first wireless device as part of performing the at least one of the DC offset calibration or the IQ imbalance calibration.

44. The apparatus of claim 43, wherein the at least one processor is further configured to measure the transmission using the receiver of the first wireless device as part of performing the DC offset calibration.

45. The apparatus of claim 43, wherein the at least one processor is configured to measure the transmission using the receiver of the first wireless device as part of performing the IQ imbalance calibration.

46. ​​The apparatus of claim 25, wherein the at least one of the DC offset calibration or the IQ imbalance calibration comprises a loopback calibration.

47. The apparatus of claim 46, wherein the DC offset calibration comprises the loopback calibration.

48. The apparatus of claim 46, wherein the IQ imbalance calibration comprises the loopback calibration.

49. An apparatus for wireless communication at a first wireless device, comprising: means for transmitting or receiving sidelink communications with a second wireless device during an active period; as well as Means for performing at least one of direct current (DC) offset calibration or in-phase or quadrature (IQ) imbalance calibration for the sidelink communication during periodic silence periods for the sidelink communication.

50. The apparatus of claim 49, wherein the periodic silence period includes a last symbol of a subframe.

51. The apparatus of claim 49, wherein the means for transmitting or receiving the sidelink communication with the second wireless device during the active period is configured to transmit the sidelink communication with the second wireless device during the active period.

52. The apparatus of claim 49, wherein the means for transmitting or receiving the sidelink communication with the second wireless device during the active period is configured to receive the sidelink communication with the second wireless device during the active period.

53. The apparatus of claim 49, wherein the means for performing is configured to perform the DC offset calibration for the sidelink communication during the periodic silence period for the sidelink communication.

54. The apparatus of claim 49, wherein the means for performing is configured to perform the IQ imbalance calibration for the sidelink communication during the periodic silence period for the sidelink communication.

55. The apparatus of claim 49, further comprising: means for selecting a gain state to be calibrated during the periodic silence period, the gain state being an untrained gain state or an older gain state having older measurements than another gain state; means for performing a measurement of direct current DC for the selected gain state during said periodic silent periods; as well as Means for updating a DC measurement for a selected gain state.

56. The apparatus of claim 55, wherein the means for updating the DC measurement is configured to update the DC measurement for the selected gain state when the signal power is less than or equal to a threshold, and the apparatus further comprises: means for discarding said measurement if said measurement includes said signal power above said threshold.

57. The apparatus of claim 49, further comprising: Means for switching from a transmit mode to a receive mode for the active period in order to perform the at least one of the DC offset calibration or the IQ imbalance calibration during the periodic silent period.

58. The apparatus of claim 49, further comprising: means for transmitting, during said periodic silence periods, a transmission below a transmit power level threshold; as well as Means for measuring the transmission using a receiver of the first wireless device as part of performing the at least one of the DC offset calibration or the IQ imbalance calibration.

59. A non-transitory computer readable medium storing computer executable code for wireless communication at a first wireless device, the code when executed by a processor causing the processor to: transmitting or receiving sidelink communications with a second wireless device during the active period; and At least one of a direct current (DC) offset calibration or an in-phase or quadrature (IQ) imbalance calibration is performed during periodic silent periods for the sidelink communication.

60. The non-transitory computer readable medium of claim 59, wherein the code, when executed by the processor, further causes the processor to: selecting a gain state to be calibrated during the periodic silence period; performing a measurement of direct current DC for the selected gain state during the periodic silent periods; and Updates the DC measurement for the selected gain state.

61. The non-transitory computer readable medium of claim 60, wherein selecting the gain state to be calibrated during the periodic silence period comprises selecting an untrained gain state to be calibrated during the periodic silence period.

62. The non-transitory computer readable medium of claim 60, wherein the code, when executed by the processor, causes the processor to: The sidelink communication is transmitted with the second wireless device during the active period.

63. The non-transitory computer readable medium of claim 60, wherein the code, when executed by the processor, causes the processor to: The sidelink communication is received with the second wireless device during the active period.

64. The non-transitory computer readable medium of claim 60, wherein the code, when executed by the processor, causes the processor to: The DC offset calibration for the sidelink communication is performed during the periodic silence period for the sidelink communication.

65. The non-transitory computer readable medium of claim 60, wherein the code, when executed by the processor, causes the processor to: The IQ imbalance calibration for the sidelink communication is performed during the periodic silence period for the sidelink communication.

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