Fast automatic gain control in bypass and filter modes

Abstract

Methods and apparatus for performing automatic gain control (AGC) in bypass and filter modes of a radio frequency (RF) front-end circuit are described. An example method includes operating a receiver in a first mode during a first set of symbols of a first subframe. The method further includes, during a first symbol of the first subframe that is outside the first set of symbols, determining whether to operate the receiver in the first mode or the second mode in the second subframe based at least in part on an output of an interference detection circuit of the receiver in the first symbol. The method further includes controlling the receiver to operate in the first mode or the second mode in the second subframe in accordance with the determination.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to U.S. patent application No. 17 / 935,044, filed on September 23, 2022, which is assigned to the assignee of this application and is hereby expressly incorporated by reference in its entirety, as if fully set forth below and for all applicable purposes. Technical Field

[0003] Certain aspects of the present disclosure relate generally to electronic circuits, and more particularly, certain aspects of the present disclosure relate to techniques and apparatus for performing automatic gain control (AGC) in wireless receiver front-end circuits. Background Art

[0004] Wireless communication devices are widely deployed to provide various communication services, such as telephony, video, data, messaging, broadcast, etc. Such wireless communication devices may send and / or receive radio frequency (RF) signals via any of a variety of suitable radio access technologies (RATs), including but not limited to 5G New Radio (NR), Long Term Evolution (LTE), Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Wideband CDMA (WCDMA), Global System for Mobile (GSM), Bluetooth, Bluetooth Low Energy (BLE), ZigBee, Wireless Local Area Network (WLAN) RATs (e.g., WiFi), etc.

[0005] A wireless communication network may include multiple base stations that can support communications for multiple mobile stations. A mobile station (MS) may communicate with a base station (BS) via a downlink and an uplink. A downlink (or forward link) refers to a communication link from a base station to a mobile station, and an uplink (or reverse link) refers to a communication link from a mobile station to a base station. A base station may send data and control information to a mobile station on a downlink, and / or may receive data and control information from a mobile station on an uplink. A base station and / or a mobile station may include a radio frequency (RF) front-end circuit that may be used, for example, for communications within a millimeter wave (mmW) communication band.

[0006] Wireless communication systems have been applied to implement wireless communication services in vehicles. For example, one type of wireless communication, known as cellular vehicle-to-everything (C-V2X) communication, provides communication of information from a vehicle to any entity through a cellular link, and vice versa. Vehicles that support C-V2X communication may be referred to as C-V2X enabled vehicles or C-V2X vehicles. A C-V2X vehicle is able to share information about itself, such as its presence, location, direction, speed, etc., with other C-V2X vehicles. Such communication between C-V2X vehicles improves safety and efficiency by allowing C-V2X vehicles to coordinate and plan driving paths along a road. However, there is a need to further improve C-V2X wireless communication systems to overcome various challenges. Summary of the invention

[0007] The systems, methods, and devices of the present disclosure each have several aspects, no single aspect of which is solely responsible for its desirable attributes. Without limiting the scope of the present disclosure as expressed by the appended claims, some features will now be briefly discussed. After considering this discussion, and particularly after reading the section entitled "Detailed Description," those skilled in the art will understand how the features of the present disclosure provide advantages, including improving the sensitivity of a receiver with minimal impact on receiver performance in the presence of interfering signals.

[0008] One aspect provides a method for wireless communication. The method includes: operating a receiver in a first mode during a first set of symbols in a first subframe. The method also includes: during a first symbol of the first subframe outside the first set of symbols, determining whether to operate the receiver in the first mode or a second mode in a second subframe based at least in part on an output of an interference detection circuit of the receiver in the first symbol. The method also includes: controlling the receiver to operate in the first mode or the second mode in the second subframe based on the determination.

[0009] On the other hand, a wireless device is provided. The wireless device includes a receiver, at least one processor coupled to the receiver, and a memory coupled to the at least one processor. The receiver includes an interference detection circuit. The memory stores computer executable instructions, and the computer executable instructions perform operations when executed by the at least one processor. The operations include: operating the receiver in a first mode during a first set of symbols in a first subframe. The operations also include: during a first symbol of the first subframe outside the first set of symbols, determining whether to operate the receiver in the first mode or the second mode in a second subframe based at least in part on an output of the interference detection circuit in the first symbol. The operations also include: controlling the receiver to operate in the first mode or the second mode in the second subframe based on the determination.

[0010] Another aspect includes an apparatus. The apparatus includes: means for receiving a signal in a first mode during a first set of symbols in a first subframe. The apparatus also includes: means for detecting the presence of an interfering signal during a first symbol of the first subframe that is outside of the first set of symbols. The apparatus also includes: means for determining whether to operate the means for receiving in the first mode or the second mode in a second subframe based at least in part on an output of the means for detecting in the first symbol. The apparatus also includes: means for controlling the means for receiving to operate in the first mode or the second mode in the second subframe based on the determination.

[0011] Other aspects provide: a non-transitory computer-readable medium including instructions, which, when executed by a processor of a device, causes the device to perform the above method and methods described elsewhere herein; and / or a computer program product embodied on a computer-readable storage medium, the computer program product including code for performing the above method and methods described elsewhere herein. For example, an apparatus may include a processing system, a device having a processing system, or a processing system cooperating through one or more networks.

[0012] To accomplish the foregoing and related ends, one or more aspects include features hereinafter fully described and particularly pointed out in the claims. The following description and the accompanying drawings set forth in detail certain illustrative features of one or more aspects. However, these features are indicative of only a few of the various ways in which the principles of the various aspects may be employed, and this description is intended to include all such aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order that the above-mentioned features of the present disclosure may be understood in detail, a more detailed description of the content briefly summarized above may be given by reference to various aspects, some of which are shown in the accompanying drawings. However, it is to be noted that the accompanying drawings only illustrate certain typical aspects of the present disclosure and are therefore not to be considered as limiting the scope thereof, as the description may allow other equally effective aspects.

[0014] Figure 1 is a diagram of an example wireless communication network in which aspects of the present disclosure may be practiced.

[0015] Figure 2 is a block diagram conceptually illustrating designs of example base stations (BSs) and user equipment (UEs) in which aspects of the present disclosure may be practiced.

[0016] Figure 3 is a block diagram of an example transceiver front end in which aspects of the present disclosure may be practiced.

[0017] Figure 4A and 4B Depicted are diagrammatic representations of an example C-V2X system in accordance with some aspects of the present disclosure.

[0018] Figure 5 Examples of sensing and selecting windows for semi-persistent scheduling in a C-V2X system are shown in accordance with some aspects of the present disclosure.

[0019] Figure 6 An example automatic gain control (AGC) scheme for a wireless receive (RX) path is shown in accordance with some aspects of the present disclosure.

[0020] Figure 7 A table showing switching points for multiple gain states of a receiver according to some aspects of the present disclosure.

[0021] Figure 8 is a flow chart of a method for performing one-step “fast” AGC according to certain aspects of the present disclosure.

[0022] Fig. 9 is a graph of signal-to-noise ratio based on single-step AGC applied to a receiver in accordance with certain aspects of the present disclosure.

[0023] Fig.10 An example RX path configured to support a filter mode and a bypass mode is shown in accordance with certain aspects of the present disclosure.

[0024] Fig.11 Further illustrating some aspects of the present disclosure Fig.10 Some components of the RX path shown in .

[0025] Fig.12 An example timeline for operating a receiver in accordance with certain aspects of the present disclosure is shown.

[0026] Fig.13 Another table showing switching points for multiple gain states of a receiver according to some aspects of the present disclosure.

[0027] Fig.14 is a flow chart of a method for performing “fast” AGC for a receiver operating in filter mode and bypass mode in accordance with certain aspects of the present disclosure.

[0028] Fig.15A Example symbols of a subframe in accordance with certain aspects of the present disclosure are shown.

[0029] Fig. 15B According to certain aspects of the present disclosure, Fig.15A Example symbols for a subframe following the subframe depicted in .

[0030] Fig. 15C According to certain aspects of the present disclosure, Fig. 15B Example symbols following the symbols depicted in .

[0031] Fig.16 is a flow chart of example operations for operating a receiver in a filter mode and a bypass mode in accordance with certain aspects of the present disclosure.

[0032] Fig.17 An example flow chart of a method for operating a receiver in accordance with certain aspects of the present disclosure is shown.

[0033] Fig.18 An example flow chart of a method for operating a receiver in accordance with certain aspects of the present disclosure is shown.

[0034] Fig.19 is a flow chart of example operations for operating a receiver in a filter mode and a bypass mode in accordance with certain aspects of the present disclosure.

[0035] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one aspect may be beneficially utilized on other aspects without specific recitation. DETAILED DESCRIPTION

[0036] Certain aspects of the present disclosure relate to techniques and apparatus for performing fast automatic gain control (AGC) in multiple operating modes (e.g., bypass and filter modes) for wireless receiver front-end circuits. The techniques described herein can improve the sensitivity of wireless receivers during wireless communications, including, for example, cellular vehicle-to-everything (C-V2X) communications.

[0037] For example, some conventional wireless receivers (e.g., conventional C-V2X receivers) typically include a bandpass filter (BPF) in a receive (RX) path of a receiver circuit (which may be part of a transceiver radio frequency (RF) front-end circuit) (before a low noise amplifier (LNA)). The BPF may be used to protect the RX operation of the wireless receiver in the presence of an interfering signal. For example, there may be a strong out-of-band (OOB) interfering signal from a wireless transmitter, and the BPF may be used to reject the OOB interfering signal. One problem with using a BPF in a conventional wireless receiver is that when the interfering signal is not present or does not affect the RX operation of the wireless receiver, the BPF may degrade the noise figure, thereby causing unnecessary desensing of the RX operation.

[0038] To address this problem, certain aspects described herein provide techniques for operating a wireless receiver in different operating modes in the RX path based on whether an interfering signal is present in the wireless receiver (e.g., a C-V2X receiver). Different operating modes may include a filter mode and a bypass mode. The filter mode may be used to protect the RX path of the wireless receiver in the presence of one or more interfering signals. For example, a wireless receiver may include a filter (e.g., a BPF) and an amplifier (e.g., an LNA) in an RX RF front-end circuit, wherein the filter is located before the amplifier. When the wireless receiver operates in filter mode in the RX path, the wireless receiver may use a filter to reject one or more interfering signals detected.

[0039] On the other hand, when the wireless receiver is not present with an interfering signal, the bypass mode can be used to increase the sensitivity of the RX path. For example, when the wireless receiver is operating in the bypass mode in the RX path, when there is no (e.g., not yet detected) interfering signal, the wireless receiver can allow the received signal to bypass the filter (e.g., BPF) in the RX RF front-end circuit, so that the RX path of the wireless receiver is minimally affected by the reduction in noise figure caused by the filter.

[0040] In certain aspects, a wireless receiver may use a filter mode in an RX path as a default mode in order to provide protection from OOB interference. For example, a wireless receiver may operate in a filter mode in an RX path during a set of symbols of a subframe, and may check for the presence of OOB interference in another symbol of the subframe outside the set of symbols. The other symbol of the subframe may be a silent mode for an (in-band) wireless transmitter. For example, assuming that the wireless receiver is part of a C-V2X transceiver, active C-V2X signals should not be sent during the other symbol of the subframe. In certain aspects, the wireless receiver may determine whether to switch to operating in bypass mode in the RX path during a subsequent subframe based at least in part on the number of times OOB interference has not been detected in the other symbol of the subframe.

[0041] In this manner, the various aspects described herein can significantly improve the performance of a wireless receiver (relative to conventional techniques) by enabling the wireless receiver to: (i) employ an operating mode in the RX path that provides an improved RX noise figure when no interfering signals are present at the wireless receiver, and (ii) employ an operating mode in the RX path that provides protection from interfering signals when the interfering signals are present at the wireless receiver.

[0042] Note that as used herein, the term "wireless receiver" may refer to the RX operation of a wireless transceiver, the RX chain of a wireless transceiver, or the RX path of a wireless transceiver. Therefore, the terms "wireless receiver", "RX operation of a wireless transceiver", "RX path of a wireless transceiver", and "RX chain of a wireless transceiver" may be used interchangeably.

[0043] The various aspects of the present disclosure are described more fully below with reference to the accompanying drawings. However, the present disclosure can be embodied in many different forms and should not be construed as being limited to any specific structure or function presented throughout the present disclosure. More specifically, these aspects are provided so that the present disclosure will be thorough and complete, and the scope of the present disclosure will be fully conveyed to those skilled in the art. Based on the teachings herein, those skilled in the art should be aware that the scope of the present disclosure is intended to cover any aspect of the disclosure disclosed herein, whether the aspect is implemented independently or in combination with any other aspect of the present disclosure. For example, using any number of aspects set forth herein, a device can be implemented or a method can be implemented. In addition, the scope of the present disclosure is intended to cover such a device or method implemented using other structures, functions, or structures and functions other than the various aspects of the present disclosure set forth herein or different from the various aspects of the present disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein can be embodied by one or more elements of the claims.

[0044] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any aspect described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects.

[0045] As used herein, in various tenses of the verb "connect," the term "connected with" may mean that element A is directly connected to element B, or that other elements may be connected between elements A and B (i.e., element A is indirectly connected to element B). In the case of electrical components, the term "connected with" may also be used herein to mean that elements A and B (and any components electrically connected therebetween) are electrically connected using wires, traces, or other conductive materials.

[0046] Exemplary Wireless Systems

[0047] Figure 1 An example wireless communication network 100 is shown in which aspects of the present disclosure may be practiced. The wireless communication network 100 may be a C-V2X communication system, a New Radio (NR) system (e.g., a fifth generation (5G) NR network), an Evolved Universal Terrestrial Radio Access (E-UTRA) system (e.g., a fourth generation (4G) network), a Universal Mobile Telecommunications System (UMTS) (e.g., a second generation / third generation (2G / 3G) network), or a Code Division Multiple Access (CDMA) system (e.g., a 2G / 3G network), or may be configured for communication in accordance with IEEE standards such as one or more of the 802.11 standards, etc.

[0048] like Figure 1 As shown, the wireless communication network 100 may include a plurality of base stations (BSs) 110a-z (each of which is also referred to herein as "BS 110" or collectively as "BS 110") and other network entities. A BS may also be referred to as an access point (AP), an evolved Node B (eNodeB or eNB), a next generation Node B (gNodeB or gNB), or some other terminology.

[0049] BS 110 may provide communication coverage for a particular geographic area (sometimes referred to as a "cell"), which may be stationary or may move depending on the location of mobile BS 110. In some examples, BS 110 may be interconnected to each other and / or to one or more other BSs or network nodes (not shown) in wireless communication network 100 through various types of backhaul interfaces (e.g., direct physical connections, wireless connections, virtual networks, etc.) using any suitable transport network. Figure 1In the example shown in FIG. 1 , BSs 110a, 110b, and 110c may be macro BSs for macro cells 102a, 102b, and 102c, respectively. BS 110x may be a pico BS for pico cell 102x. BSs 110y and 110z may be femto BSs for femto cells 102y and 102z, respectively. A BS may support one or more cells.

[0050] The BS 110 communicates with one or more user equipment (UE) 120a-y (each also referred to herein individually as "UE 120" or collectively as "UE 120") in the wireless communication network 100. A UE may be fixed or mobile and may also be referred to as a user terminal (UT), a mobile station (MS), an access terminal, a station (STA), a client, a wireless device, a mobile device, or some other terminology. A user terminal may be a wireless device such as a cellular phone, a smart phone, a personal digital assistant (PDA), a handheld device, a wearable device, a wireless modem, a laptop, a tablet, a personal computer, a vehicle (e.g., a car, a truck, a motorcycle, a boat, or any other means of transportation), etc.

[0051] BS 110 is considered a transmitting entity for downlink and a receiving entity for uplink. UE 120 is considered a transmitting entity for uplink and a receiving entity for downlink. As used herein, a "transmitting entity" is an independently operated device or apparatus capable of transmitting data via a frequency channel, and a "receiving entity" is an independently operated device or apparatus capable of receiving data via a frequency channel. In the following description, the subscript "dn" indicates a downlink, and the subscript "up" indicates an uplink. N may be selected. up UEs are used for simultaneous transmission on the uplink, N dn UEs are used for simultaneous transmission on the downlink. up May or may not be equal to N dn , and N up and N dn It may be a static value, or may change for each scheduling interval.Beam steering or some other spatial processing technique may be used at the BS 110 and / or the UE 120.

[0052] UEs 120 (e.g., 120x, 120y, etc.) may be dispersed throughout the wireless communication network 100, and each UE 120 may be stationary or mobile. The wireless communication network 100 may also include a relay station (e.g., relay station 110r) (also referred to as a relay, etc.) that receives transmissions of data and / or other information from an upstream station (e.g., BS110a or UE 120r) and sends transmissions of the data and / or other information to a downstream station (e.g., UE 120 or BS110), or relays transmissions between UEs 120 to facilitate communication between devices. In addition, in some aspects, the wireless communication network 100 may include UEs (e.g., UEs 120a, 120b, 120c) that communicate directly with each other via sidelinks according to the C-V2X standard, as described in more detail below.

[0053] BS 110 may communicate on the downlink and uplink with one or more UEs 120 at any given moment. The downlink (i.e., forward link) is the communication link from BS 110 to UE 120, and the uplink (i.e., reverse link) is the communication link from UE 120 to BS 110. A UE 120 may also communicate peer-to-peer with another UE 120.

[0054] The wireless communication network 100 may use multiple transmit antennas and multiple receive antennas for data transmission on the downlink and uplink. The BS 110 may be equipped with N ap antennas to achieve transmit diversity for downlink transmission and / or receive diversity for uplink transmission. u Each UE 120 may receive downlink transmissions and send uplink transmissions. Each UE 120 may send user-specific data to and / or receive user-specific data from BS 110. Typically, each UE 120 may be equipped with one or more antennas. u The UEs 120 may have the same or different numbers of antennas.

[0055] The wireless communication network 100 may be a time division duplex (TDD) system or a frequency division duplex (FDD) system. For a TDD system, the downlink and uplink share the same frequency band. For an FDD system, the downlink and uplink use different frequency bands. The wireless communication network 100 may also utilize a single carrier or multiple carriers for transmission. Each UE 120 may be equipped with a single antenna (e.g., to reduce costs) or multiple antennas (e.g., in the case of supporting additional costs).

[0056] The network controller 130 (sometimes also referred to as a "system controller") can communicate with a set of BSs 110 and provide coordination and control for these BSs 110 (e.g., via a backhaul). In some cases (e.g., in a 5G NR system), the network controller 130 may include a centralized unit (CU) and / or a distributed unit (DU). In some aspects, the network controller 130 may communicate with a core network 132 (e.g., a 5G core network (5GC)), which provides various network functions such as access and mobility management, session management, user plane functions, policy control functions, authentication server functions, unified data management, application functions, network open functions, network repository functions, network slice selection functions, etc.

[0057] In certain aspects of the present disclosure, BS 110 and / or UE 120 may include RF front-end circuitry that supports multiple operating modes in the RX path, including, for example, a filter mode and a bypass mode.

[0058] Figure 2 1 shows a BS 110a and a UE 120a (eg, from a Figure 1 Example components of a wireless communication network 100).

[0059] On the downlink, at BS 110a, a transmit processor 220 may receive data from a data source 212, control information from a controller / processor 240, and / or possibly other data (e.g., from a scheduler 244). Various types of data may be sent on different transport channels. For example, control information may be designated for a physical broadcast channel (PBCH), a physical control format indicator channel (PCFICH), a physical hybrid automatic repeat request (HARQ) indicator channel (PHICH), a physical downlink control channel (PDCCH), a group common PDCCH (GC PDCCH), etc. Data may be designated for a physical downlink shared channel (PDSCH), etc. A medium access control (MAC)-control element (MAC-CE) is a MAC layer communication structure that may be used for control command exchange between wireless nodes. A MAC-CE may be carried in a shared channel such as a PDSCH, a physical uplink shared channel (PUSCH), or a physical sidelink shared channel (PSSCH).

[0060] The processor 220 may process (e.g., encode and symbol map) data and control information to obtain data symbols and control symbols, respectively. The transmit processor 220 may also generate reference symbols such as for a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a PBCH demodulation reference signal (DMRS), and a channel state information reference signal (CSI-RS).

[0061] The transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on ​​data symbols, control symbols, and / or reference symbols (if applicable), and may provide an output symbol stream to a modulator (MOD) in a transceiver 232a-232t. Each modulator in the transceiver 232a-232t may process a respective output symbol stream (e.g., for orthogonal frequency division multiplexing (OFDM), etc.) to obtain an output sample stream. Each transceiver in the transceiver 232a-232t may further process (e.g., convert to analog, amplify, filter, and up-convert) the output sample stream to obtain a downlink signal. The downlink signals from the transceivers 232a-232t may be transmitted via antennas 234a-234t, respectively.

[0062] At UE 120a, antennas 252a-252r may receive downlink signals from BS110a and may provide received signals to transceivers 254a-254r, respectively. Transceivers 254a-254r may condition (e.g., filter, amplify, downconvert, and digitize) respective received signals to obtain input samples. Each demodulator (DEMOD) in transceivers 232a-232t may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. MIMO detector 256 may obtain received symbols from all demodulators in transceivers 254a-254r, perform MIMO detection on the received symbols (if applicable), and provide detected symbols. Receive processor 258 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for UE 120a to data sink 260, and provide decoded control information to controller / processor 280. In certain aspects, the UE 120a may include RF front-end circuitry that may support multiple operating modes in the RX path including, for example, a filter mode and a bypass mode.

[0063] On the uplink, at the UE 120a, a transmit processor 264 may receive and process data from a data source 262 (e.g., for a physical uplink shared channel (PUSCH)) and control information from a controller / processor 280 (e.g., for a physical uplink control channel (PUCCH)). The transmit processor 264 may also generate reference symbols for reference signals (e.g., a sounding reference signal (SRS)). The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266 (if applicable), further processed by a modulator (MOD) in the transceiver 254a-254r (e.g., for single carrier frequency division multiplexing (SC-FDM), etc.), and transmitted to the BS 110a. At BS 110a, the uplink signal from UE 120a may be received by antenna 234, processed by demodulators in transceivers 232a-232t, detected by MIMO detector 236 (if applicable), and further processed by receive processor 238 to obtain decoded data and control information sent by UE 120a. Receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to a controller / processor 240.

[0064] Memories 242 and 282 may store data and program codes for BS 110a and UE 120a, respectively. Memories 242 and 282 may also interface with controllers / processors 240 and 280, respectively. Scheduler 244 may schedule UEs for data transmission on the downlink and / or uplink.

[0065] The antennas 252, processors 258, 264, 266 and / or controller / processor 280 of the UE 120a and / or the antennas 234, processors 220, 230, 238 and / or controller / processor 240 of the BS 110a may be used to perform the various techniques and methods described herein.

[0066] Example Transceiver Front End

[0067] Figure 3is a block diagram of an example transceiver front end 300 (also referred to as transceiver circuitry) in accordance with certain aspects of the present disclosure. The transceiver front end 300 includes at least one transmit (TX) path 302 (also referred to as a "transmit (TX) chain" or "transmit (TX) operation") for transmitting signals via one or more antennas 306 and at least one receive (RX) path 304 (also referred to as a "receive (RX) chain" or "receive (RX) operation") for receiving signals via antenna 306. When the TX path 302 and the RX path 304 share an antenna 306, these paths can be connected to the antenna via an interface 308, which can include any of a variety of suitable RF devices, such as switches, duplexers, antenna sharing devices, multiplexers, etc. Note that although in Figure 3 A single RX path and a single TX path are depicted in FIG. 3 , but the transceiver front end 300 may include multiple RX paths and / or multiple TX paths, which may be connected to one or more antennas 306 .

[0068] Receiving in-phase (I) and / or quadrature (Q) baseband analog signals from a digital-to-analog converter (DAC) 310, the TX path 302 may include a baseband filter (BBF) 312, a mixer 314, a driver amplifier (DA) 316, and a power amplifier (PA) 318. The BBF 312, the mixer 314, the DA 316, and the PA 318 may be included in a radio frequency integrated circuit (RFIC). For certain aspects, the PA 318 may be external to the RFIC.

[0069] The BBF 312 filters the baseband signal received from the DAC 310, and the mixer 314 mixes the filtered baseband signal with a transmit local oscillator (LO) signal to convert the baseband signal of interest to a different frequency (e.g., upconvert from baseband to radio frequency). This frequency conversion process produces sum and difference frequencies of the LO frequency and the frequency of the baseband signal of interest. The sum and difference frequencies are referred to as "beat frequencies." The beat frequencies are typically in the RF range, so that the signal output by the mixer 314 is typically an RF signal, which is amplified by the DA 316 and / or by the PA 318 before being transmitted through the antenna 306. Although one mixer 314 is shown, several mixers may be used to upconvert the filtered baseband signal to one or more intermediate frequencies, and thereafter upconvert the intermediate frequency (IF) signal to a frequency for transmission.

[0070] RX path 304 may include filter 340, low noise amplifier (LNA) 324, mixer 326 and baseband filter (BBF) 328. Filter 340 may be a passive filter, such as a BPF. Filter 340, LNA 324, mixer 326 and BBF 328 may be included in one or more RFICs, which may or may not be the same RFIC that includes TX path components. RF signals received via antenna 306 may be filtered by filter 340 and amplified by LNA 324. Mixer 326 mixes the amplified RF signal with a receive local oscillator (LO) signal to convert the RF signal of interest to a different baseband frequency (e.g., down conversion). The baseband signal output by mixer 326 may be filtered by BBF 328 before being converted to digital I and / or Q signals by analog-to-digital converter (ADC) 330 for digital signal processing.

[0071] Certain transceivers (e.g., C-V2X transceivers) may use filter 340 to provide protection from OOB interference. For example, filter 340 may be used to reject OOB interference signals that may cause desensing of RX path 304. However, in scenarios where OOB interference signals are not present, filter 340 may degrade the noise figure (NF) of RX path 304 and thereby cause unnecessary desensing of RX operations.

[0072] Some transceivers may employ a frequency synthesizer with a variable frequency oscillator (e.g., a voltage controlled oscillator (VCO) or a digitally controlled oscillator (DCO)) to generate a stable, tunable LO with a specific tuning range. Thus, the transmit LO may be generated by the TX frequency synthesizer 320, which may be buffered or amplified by the amplifier 322 before being mixed with the baseband signal in the mixer 314. Similarly, the receive LO may be generated by the RX frequency synthesizer 332, which may be buffered or amplified by the amplifier 334 before being mixed with the RF signal in the mixer 326. For certain aspects, a single frequency synthesizer may be used for both the TX path 302 and the RX path 304. In certain aspects, the TX frequency synthesizer 320 and / or the RX frequency synthesizer 332 may include a frequency multiplier, such as a doubler, driven by an oscillator (e.g., a VCO) in the frequency synthesizer.

[0073] Controller 336 (eg, Figure 2The controller / processor 280 in the example embodiment may direct the operation of the transceiver front end 300, such as transmitting signals via the TX path 302 and / or receiving signals via the RX path 304. The controller 336 may be a processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof. The memory 338 (e.g., Figure 2 The memory 282 in the controller 336 may store data and / or program codes for operating the transceiver front end 300. The controller 336 and / or the memory 338 may include control logic (eg, complementary metal oxide semiconductor (CMOS) logic).

[0074] Example C-V2X System

[0075] C-V2X may include vehicle-to-vehicle (V2V), vehicle-to-pedestrian (V2P), vehicle-to-infrastructure (V2I), vehicle-to-network (V2N), and combinations thereof. Figure 4A and Figure 4B Depicted are diagrammatic representations of an exemplary C-V2X system in accordance with some aspects of the present disclosure.

[0076] Figure 4A and Figure 4B The C-V2X system shown in FIG. 1 provides two complementary transmission modes. The first transmission mode (in Figure 4A 404, a roadside unit (RSU) (e.g., a traffic light 410)) can be implemented via a PC5 interface (e.g., a wireless communication interface between a first UE and a second UE). The second transmission mode (in Figure 4B ) may involve network communication through a network, which may be achieved through a Uu interface (eg, a wireless communication interface between a radio access network (RAN) and a UE).

[0077] Reference Figure 4A, a C-V2X system 400 (e.g., V2V communication, also referred to as C-V2X Mode 4) is shown with two vehicles 402, 404. The first transmission mode allows direct communication between different participants in a given geographic location. As shown, the vehicle can have a wireless communication link 406 with a person (V2P) (e.g., with a person's mobile phone) via a PC5 interface. Communication between vehicles 402 and 404 can also occur via a PC5 interface 408. In a similar manner, communication can be carried out from vehicle 402 to other highway components (such as traffic signals (e.g., traffic lights 410) or signs (V2I)) via a PC5 interface 412. Regarding Figure 4A Each communication link shown in , enables bidirectional communication between elements, so each element can be a sender and receiver of information.

[0078] The V2X system 400 may be a self-managed system implemented without the assistance of a network entity. Since no network service interruption occurs during handover operations for moving vehicles, the self-managed system may achieve improved spectrum efficiency, reduced costs, and improved reliability. The V2X system 400 may be configured to operate in licensed and / or unlicensed spectrum so that any vehicle with an equipped system may access common frequencies and share information. Such coordinated / common spectrum operations may allow for safe and reliable operations.

[0079] Figure 4B A V2X system 450 is shown for communicating between a vehicle 452 and a vehicle 454 through a network entity 456. These network communications may occur through discrete nodes, such as a BS (e.g., a BS) that sends information to and receives information from (or relays information between) the vehicles 452, 454. Figure 1 10a). For example, network communications via V2N links 458 and 411 can be used for long-distance communications between vehicles, for example, for communicating a car accident a distance ahead along a road or highway. Wireless nodes can send other types of communications to vehicles, such as traffic flow conditions, road hazard warnings, environmental / weather reports, and service station availability, among other examples. Such data can be obtained from cloud-based sharing services.

[0080] As previously mentioned, some V2X systems may be self-managed systems implemented without the assistance of network entities. For example, C-V2X Mode-4 (also known as V2V) may operate without infrastructure support and may use specific resource pool configurations and semi-persistent scheduling (SPS) to select and reserve resources for transmission. In V2V, sidelink control information may be sent on a physical sidelink control channel (PSCCH) and data may be sent on a physical sidelink shared channel (PSSCH). The sidelink control information may carry information related to the transmission of data on the PSSCH.

[0081] C-V2X Mode-4 uses sensing to determine appropriate SPS transmission opportunities (e.g., the set of subframes and subchannels for transmission). Figure 5 An example of a sensing and selection window for SPS in C-V2X is shown in FIG. As shown, the sensing window 502 may span multiple subframes (e.g., Figure 5 1000 subframes depicted in FIG. 5 ). Within sensing window 502, the UE may select a set of candidate single subframe resources (e.g., L subchannels) within selection window 504. Selection window 504 may span multiple subframes and include M single subframe resources. Figure 5 As shown, parameters T1 and T2 may define a selection window 504. The selection window 504 may occur once every P subframes.

[0082] Example Fast Automatic Gain Control for C-V2X Transceiver Front End

[0083] The C-V2X transceiver (e.g., transceiver front end 300) may transmit at a low duty cycle (e.g., ~2%). For example, the C-V2X transceiver may transmit once every 100 milliseconds (ms), 200 ms, or 300 ms. Each UE may transmit C-V2X transmit signals in burst mode. Similarly, when receiving C-V2X signals, the C-V2X transceiver may also operate in burst mode in the RX path on a subframe-by-subframe basis. The C-V2X transceiver may operate without a continuous loop in the RX path.

[0084] Relative to some signals (e.g., LTE signals), C-V2X signals may change randomly between subframes, with each subframe having a different frequency allocation and received signal power. In some cases, "fast" AGC logic may be used to adjust the gain at the beginning of each subframe in less than one symbol time.

[0085] Figure 6An example AGC scheme 600 for a wireless RX path (e.g., RX path 304) according to certain aspects of the present disclosure is shown. The AGC scheme 600 can be used to implement a "fast" AGC, where the gain is adjusted at the beginning of each subframe in less than one symbol time. As shown, the controller 336 includes a mapper component 602, a wideband energy estimation (WBEE) component 604, a wideband signal DC estimation (WBDC) component 606, a decimation filter component 608, a decimation filter component 610, an AGC logic 612, and a digital processing component 614.

[0086] In the AGC scheme 600, the ADC 330 can output digital signals (e.g., digital I and / or Q signals) for digital signal processing by the controller 336. For example, the controller 336 can demap the digital signals (via the mapper component 602), downsample the digital signals (via the decimation filter components 608 and 610), and further process (e.g., decode) the digital signals (via the digital processing component 614). In certain aspects, the controller 336 can estimate the wideband signal energy of the digital signal using the WBEE component 604 and estimate the wideband DC offset of the digital signal using the WBDC component 606. The controller 336 can use the AGC logic 612 to adjust the gain of the RF chain (e.g., LNA 324, mixer 326) and the gain of the baseband chain (e.g., BBF 328, ADC 330).

[0087] The AGC logic 612 may start with an initial gain and may select a final gain to converge to based on the WBEE of the digital signal (determined via the WBEE component 604). In some aspects, the DC offset generated at the receiver mixer is output from the WBEE of the digital signal. For example, DC offset estimation and cancellation may be provided by the WBDC component 606. DC offset estimation and cancellation for active receiver AGC gain may affect the decision of the AGC logic 612, RX path sensitivity, and signal-to-noise ratio (SNR).

[0088] In some aspects, the AGC logic 612 can adjust the gain in one step to allow for a fast settling time in less than one symbol time (e.g., less than 30 microseconds (us)). In some aspects, the AGC logic 612 can adjust the gain in more than one step (e.g., two steps). Figure 7 Table 700 shows switching points for multiple gain states (GS) at the RX antenna input of a receiver according to certain aspects of the present disclosure. The switching points in table 700 are based on 12 GS (e.g., G0 to G11) that can be used to perform "fast" AGC on the RX path of the receiver. For example, the AGC logic 612 can be from Figure 6The gain state is selected from the 12 gain states of the cascaded RF+BB gain of the AGC scheme 600 depicted in Table 700. Each gain state G0 to G11 can have a backoff (BO) referenced to the ADC full scale (FS) taking into account signal peak-to-average power ratio (PAPR) and fading. In the example depicted in Table 700, each gain state has an 18dB BO.

[0089] Figure 8 is a flow chart of a method 800 for performing one-step "fast" AGC according to certain aspects of the present disclosure. The method 800 may be performed by a controller (e.g., controller 336). In some aspects, the method 800 may be performed using Figure 7 700 to perform method 800. For example, the controller may be Figure 6 In some aspects, the cascaded RF+baseband gain of the AGC scheme 600 depicted in FIG. 6 may be used to select one of the multiple gain states depicted in the table 700. Fig.13 1300 to perform method 800. For example, the controller may be Figure 6 One of the multiple gain states depicted in the cascaded RF+baseband gain selection table 1300 of the AGC scheme 600 depicted in FIG.

[0090] Method 800 may enter at block 802, where a controller sets an initial gain state (GS) to G1 (eg, Figure 7 G1 depicted in Table 700 of FIG. 1 ). At block 804, the controller reads the WBEE after a predetermined amount of time has passed from the start of the subframe. In some aspects, the WBEE detection range may be less than the ADC dynamic range. In the reference example, the WBEE detection range may be approximately 32 dB (with a BO of 18 dB from the ADC FS) at the receiver switching point, while the ADC dynamic range may be approximately 75 dB.

[0091] Since the WBEE detection range may be smaller than the ADC dynamic range, various aspects described herein may use multiple ranges and / or thresholds over the ADC dynamic range for gain state selection. Figure 7For example, range 702 may be used for detection over the lowest range of the WBEE detection range to select a first set of gain states (e.g., G1 and G0 depicted in table 700, based on WBEE within 16 dBm below the G1 to G2 switch point). In some cases, range 702 may include a sub-range 704 for selecting a first gain state within the first set of gain states (e.g., G0 depicted in table 700, based on WBEE within 4 dBm below the G0 to G1 switch point) and a sub-range 706 for selecting a second gain state within the first set of gain states (e.g., G1 depicted in table 700, based on WBEE within 12 dBm above the G0 to G1 switch point). Range 708 may be used for an upper range of the WBEE detection range, which is used to select a second set of gain states (e.g., G2 to G5 depicted in table 700, based on detection within 16 dBm above the G1 to G2 switch point). Additionally, range 710 may be used to select a third set of gain states (eg, G10 or G11 depicted in table 700) when the WBEE exceeds its detection range (eg, G10 depicted in table 700 may be selected when the WBEE is greater than the G5 to G6 switch point).

[0092] Return to reference Figure 8 , at block 806, the controller determines whether the WBEE satisfies a first condition. The first condition may include whether the WBEE is within a first range (e.g., range 708). If at block 806, the controller determines that the WBEE satisfies the first condition, the controller selects a gain state from a set of gain states associated with the first range (e.g., G2 to G5 depicted in table 700) (block 808) and proceeds to the start of the next (or subsequent) subframe. If at block 806, the controller determines that the WBEE does not satisfy the first condition (e.g., the WBEE is not within the first range), the controller proceeds to block 812.

[0093] At block 812, the controller determines whether the WBEE satisfies a second condition. The second condition may include whether the WBEE exceeds the detection range (e.g., the WBEE is within range 710). If at block 812, the controller determines that the WBEE satisfies the second condition, the controller selects a gain state from a set of gain states associated with the WBEE exceeding its detection range (e.g., G10 and G11 depicted in table 700) (block 810) and continues to the beginning of the next (or subsequent) subframe. If at block 812, the controller determines that the WBEE does not satisfy the second condition (the WBEE does not exceed its detection range), the controller proceeds to block 814.

[0094] At block 814, the controller determines whether the WBEE satisfies a third condition. The third condition may include whether the WBEE is within the second range (e.g., sub-range 706). If at block 814, the controller determines that the WBEE satisfies the third condition, the controller selects a gain state from a set of gain states associated with the second range (e.g., G1 depicted in table 700) (block 816) and proceeds to the start of the next (or subsequent) subframe. If at block 814, the controller determines that the WBEE does not satisfy the third condition (e.g., the WBEE is not within the second range), the controller proceeds to block 818.

[0095] At block 818, the controller determines whether the WBEE satisfies a fourth condition. The fourth condition may include whether the WBEE is within a third range (e.g., sub-range 704). If at block 818, the controller determines that the WBEE satisfies the fourth condition, the controller selects a gain state from a set of gain states associated with the third range (e.g., G0 depicted in table 700) (block 820) and continues to the beginning of the next (or subsequent) subframe. If at block 818, the controller determines that the WBEE does not satisfy the fourth condition (e.g., the WBEE is not within the third range), the controller determines that there is a WBEE error, may maintain the gain state (e.g., at G1) (block 822), and may continue to the beginning of the next (or subsequent) subframe.

[0096] Fig. 9 900 is a graph of SNR based on a single-step "fast" AGC applied to an RX path (e.g., RX path 304) of a wireless receiver in accordance with certain aspects of the present disclosure. As shown, the SNR may increase until the WBEE range reaches the G5 switch point. When the WBEE range exceeds the G5 switch point (e.g., WBEE>-31 dBm), the AGC logic switches from G5 to G10, which results in a decrease in SNR.

[0097] Example Fast Automatic Gain Control in Bypass and Filter Modes

[0098] As previously described, some conventional wireless receivers (e.g., conventional C-V2X receivers) typically include a filter (e.g., BPF) in the RX RF front-end circuit (before the amplifier (e.g., BPF)), and use the filter to mitigate the impact of interference signals on the RX path of the wireless receiver. However, although the filter can be used to mitigate the impact of the interference signal, the filter may reduce the RX noise figure, thereby causing unnecessary de-sensing of the RX operation when the interference signal is not present.

[0099] Therefore, certain aspects described herein provide techniques for operating a wireless receiver in different operating modes in an RX path based on whether there is an interference signal in the wireless receiver. The operating mode may include, for example, a filter mode and a bypass mode. When the wireless receiver detects an interference signal exceeding a predefined threshold, the wireless receiver may operate in a filter mode in the RX path. For example, the filter mode may protect the RX path of the wireless receiver from the influence of the OOB interference signal, including, for example, compression of two-tone intermodulation products in the frequency band of the RX path of the wireless receiver. On the other hand, when there is no interference signal in the wireless receiver (for example, the wireless receiver does not detect the interference signal within a predefined amount of time), the wireless receiver may operate in a bypass mode in the RX path. When operating in a bypass mode in the RX path, the wireless receiver may allow the received signal to bypass the filter (for example, BPF) in the RX path, so that the RX path is minimally affected by the reduction of the noise coefficient caused by the filter.

[0100] Fig.10 An example RX path 1004 of a receiver front end 1000 configured to support filter mode and bypass mode according to certain aspects of the present disclosure is shown. For certain aspects, the receiver front end 1000 can be part of a transceiver front end, such as Figure 3 As shown in the figure, the transceiver front end 300 Figure 3 Compared to the illustrated RX path 304 of the transceiver front end 300, the RX path 1004 includes a switch 1006 coupled in parallel with the filter 340 (eg, BPF) that allows the filter 340 to be bypassed. The operation of the switch 1006 may be controlled by the controller 336, for example.

[0101] Fig.11 An example of interference detection circuitry for the RX path 1004 of the receiver front end 1000 in accordance with certain aspects of the present disclosure is shown. The interference detection circuitry includes an interference detection circuit 1102, an interference detection circuit 1106, and a logic ("OR") gate 1104. The interference detection circuit 1102 has an input coupled to the bypass path (e.g., via the switch 1006) from the antenna 306. The interference detection circuit 1106 has an input coupled to the output of the LNA 324.

[0102] Interference detection circuits 1102 and 1106 may include circuitry for determining the power of a received analog signal. Each of interference detection circuits 1102 and 1106 may generate a corresponding logic signal indicating whether an interference signal has been detected (e.g., the power of the received analog signal is greater than a threshold). Logic gate 1104 may receive logic signals from interference detection circuits 1102 and 1106 and output a logic signal 1108 indicating whether an interference signal has been detected.

[0103] In some aspects, the RX path 1004 can be configured to use the filter mode as a default mode during a first set of symbols of a subframe and to use the bypass mode during at least a portion of a second symbol outside of the first set of symbols of the subframe to check for the presence of an interference signal (e.g., determine whether the logic signal 1108 indicates that an interference signal has been detected). For example, some communication systems (C-V2X communication systems) may allow a wireless transmitter to be active during the first set of symbols of a subframe, but may not allow the wireless transmitter to be active during the second symbol of the subframe. Reference Fig.12 In the example timeline 1200 shown in FIG. 1 , a wireless transmitter (e.g., a C-V2X transmitter) may be active on symbols 0 to 12 of subframe 1202 and may be inactive (e.g., in a muting mode or blanking mode) during symbol 13 of subframe 1202.

[0104] In certain aspects, because the wireless transmitter may be active on symbols 0 to 12 of subframe 1202, the RX path may be configured (via controller 336) to operate in filter mode during symbols 0 to 12 of subframe 1202 in order to protect the RX path from interference signals. In certain aspects, the RX path may be configured (via controller 336) to use the symbol 13 quiet period to switch to bypass mode in order to detect whether an interference signal has been detected. For example, the controller 336 may check whether the logic signal 1108 indicates that an interference signal has been detected during the symbol 13 quiet period. In one aspect, the RX path may be configured to switch back to filter mode on symbols 0 to 12 of a subsequent subframe. In another aspect, if the controller 336 determines that the number of times that an interference signal has not been detected at symbol 13 is greater than a threshold, the controller 336 may configure the RX path to switch to bypass mode for at least symbols 0 to 12 of a subsequent subframe, rather than switching back to filter mode on symbols 0 to 12 in a subsequent subframe.

[0105] In some aspects, the controller 336 can perform "fast" AGC on the RX path 1004 when the RX path is operating in filter mode and bypass mode. Figure 8 The method 800 and Figure 7As shown in Table 700, the controller 336 can perform "fast" AGC on the RX path 1004 when the RX path is operating in filter mode. Figure 8 The method 800 and Fig.13 As shown in table 1300 of switch points for multiple gain states of the receiver, controller 336 may perform “fast” AGC on RX path 1004 when the RX path is operating in bypass mode.

[0106] In certain aspects, after the RX path is switched to bypass mode, the RX path may continue to operate in bypass mode until an interference signal has been detected (e.g., logic signal 1108 indicates that an interference signal has been detected). When an interference signal has been detected, the controller 336 may configure the RX path to switch back to filter mode to protect the RX path from sensing due to the interference signal. Note that in some cases, due to the conversion between filter mode and bypass mode, potential damage may be caused to the symbol (and subframe) (in which the conversion occurs). In such a case, when switching between bypass mode and filter mode, the controller 336 may perform at least one of amplitude correction or phase correction to reduce (or eliminate) the damage of lost symbols and related subframes.

[0107] Fig.14 1004) is a flow chart of a method 1400 for performing "fast" AGC on a receiver front end (e.g., receiver front end 1000) supporting filter mode and bypass mode in an RX path (e.g., RX path 1004) in accordance with certain aspects of the present disclosure. The method 1400 may be controlled by a controller (e.g., controller 336).

[0108] Method 1400 may be entered at block 1450, where the controller configures the receiver front end to operate in a filter mode (e.g., BPF mode) in the RX path. As part of configuring the receiver front end to operate in the filter mode in the RX path, the controller may set an interference counter (CNTR-J) to 0 (or some other initial value). The interference counter may be used to track the number of times an interference signal has not been detected in a symbol (e.g., symbol 13) of a subframe. When the receiver front end is configured to operate in the filter mode, the controller may use a set of gains and switching points associated with the filter mode (e.g., Figure 7 700 shown in FIG.

[0109] At block 1402, in symbol 0 of a subframe, the controller sets the DC correction value (K) to 1 / 0 and sets the gain to G1. At block 1404, in symbol 0 of a subframe, the controller reads the WBEE and selects a gain state from a set of gain states based on the WBEE. Figure 7 The operations in blocks 1402 and 1404 are performed with the gain states shown in table 700. At block 1406, the controller sets the DC correction value (K) to 4 / 3 at a point in time during symbols 1 to 12 of the subframe.

[0110] At block 1408, during symbol 13 of the subframe, the controller updates the DC correction value (K) to 6 / 5. Fig.15A (which shows example symbol 13 of subframe N-1), the controller changes the DC correction value between t0 and t1 of symbol 13 of subframe N-1. At block 1410, the controller configures the RX path to operate in bypass mode and reads the state of the jammer detection circuitry (e.g., logic signal 1108). Fig.15A As shown, for example, the controller reads the state of the jammer detection circuitry at t2 of symbol 13 of subframe N-1.

[0111] At block 1412, the controller determines whether the state of the interference detection circuitry is "1" or "0" (e.g., logic signal 1108 is "1" or "0"). If the state of the interference detection circuitry is "1", the controller configures the receiver front end to continue operating in filter mode in the RX path for subsequent subframes. Fig.15A As shown, for example, the RX path switches to filter mode at t2 of symbol 13 of subframe N-1 and may continue in filter mode for at least a portion of subframe N. After determining that the state of the jammer detection circuitry is "1" in block 1412, the controller may or may not update the DC-LUT.

[0112] On the other hand, if the state of the jammer detection circuit is "0", the controller updates the DC lookup table (LUT) (block 1414). Fig.15A As shown in , the controller Fig.15A The DC LUT update is performed at t3 of symbol 13 of subframe N-1 as shown. The controller also updates (eg, increments) an interference counter (CNTR-J) (block 1416) and determines whether the interference counter reaches a threshold (eg, 1000 or some other value) (block 1410).

[0113] If the interference counter has not reached the threshold, the controller configures the receiver front end to continue operating in the filter mode in the RX path for subsequent subframes, e.g. Fig.15AAs shown. On the other hand, if the interference counter has reached the threshold, the controller proceeds to 1460, where the controller configures the receiver front end to operate in bypass mode in the RX path for the subsequent subframe. Note that in some cases, the controller may still configure the receiver front end to switch back to filter mode for the remainder of symbol 13 of the current subframe regardless of the determination of whether to switch to bypass mode for the subsequent subframe or to remain in filter mode for the subsequent subframe. For example, Fig.15A As shown, after the interference detection circuit (JDET) reads at t2 of symbol 13 of subframe N-1, the RX path switches back to filter mode.

[0114] When the receiver front end is configured to operate in bypass mode, the controller may use a set of gains and switching points associated with the bypass mode (e.g., Fig.13 1300 shown in FIG. 1300). Except that blocks 1422 and 1424 are used Fig.13 The operations in blocks 1422 and 1424 are similar to the operations in blocks 1402 and 1404, respectively, except that the selected gain state is performed at the gain state shown in Table 1300 of FIG. 1426. At block 1426, the controller determines whether the selected gain state is greater than G1. If so, the controller configures the receiver front end to operate in filter mode in the RX path for the remainder of the subframe (e.g., as Fig. 15B ). If the selected gain state is not greater than G1, the controller updates the DC correction value K=6 / 5 (block 1428). At block 1430, the controller reads the state of the interference detection circuitry in symbol 13. At block 1432, the controller determines whether the state of the interference detection circuitry is "1" or "0". If the state of the interference detection circuitry is "0", the controller updates the DC-LUT (block 1434) and configures the receiver front end to continue operating in bypass mode in the RX path for subsequent subframes (e.g., as shown in FIG. 14A ). Fig. 15C On the other hand, if the state of the jammer detection circuit is "1", the controller avoids updating the DC-LUT (block 1420) and configures the receiver front end to operate in filter mode in the RX path for subsequent subframes (e.g., as shown in FIG. 14A ). Fig. 15C shown).

[0115] Note that while method 1400 describes setting the interference counter to 0 and incrementing the interference counter until the counter reaches a threshold (e.g., 1000), in some aspects method 1400 may also be implemented by setting the interference counter to a threshold value (e.g., 1000) and decrementing the interference counter until the counter reaches 0. Also, note that while method 1400 describes checking the state of the RF interference detection circuitry for OOB interference signals, in some aspects the controller may perform WiFi detection in the digital domain to determine whether to switch from filter mode to bypass mode.

[0116] Example Operation

[0117] Fig.16 is a flow diagram of example operations 1600 for operating a receiver (eg, the RX path 1004 of the receiver) in a filter mode and a bypass mode in accordance with certain aspects of the present disclosure.

[0118] Operations 1600 may generally involve, at block 1602 , operating a receiver (e.g., RX path 1004 ) in a first mode (e.g., filter mode) during a first set of symbols (e.g., symbols 0-12) of a first subframe (e.g., subframe N-1).

[0119] Operation 1600 also involves: at box 1604, during a first symbol (e.g., symbol 13) outside the first symbol set of the first subframe, determining whether to operate the receiver in the first mode or the second mode (e.g., bypass mode) in a second subframe (e.g., subframe N) based at least in part on an output (e.g., logic signal 1108) of a receiver interference detection circuit (e.g., interference detection circuit 1102, interference detection circuit 1106) in the first symbol.

[0120] Operations 1600 also involve, at block 1606, controlling the receiver to operate in the first mode or the second mode in the second subframe based on the determination.

[0121] In one aspect, operations 1600 may also include operating a transmitter (e.g., TX path 302 of transceiver front end 300), wherein the transmitter is configured to refrain from transmitting during a first symbol. In one aspect, the first symbol (e.g., symbol 13) may be after a first set of symbols (e.g., symbols 0-12) of a first subframe (e.g., subframe N-1). In one aspect, the receiver may be configured to receive a C-V2X receive signal.

[0122] In one aspect, operation 1600 may also include switching from operating the receiver in the first mode to operating the receiver in the second mode for the first portion of the first symbol. In this aspect, determining (in block 1604) may be based on an output of an interference detection circuit in the first portion of the first symbol.

[0123] For example, when the output of the interference detection circuit indicates that WiFi or any out-of-band interference signal has been detected, the determination (in block 1604) may be to operate the receiver in the first mode in the second subframe. In another example, when the output of the interference detection circuit indicates that an interference signal has been detected, the determination (in block 1604) may be to operate the receiver in the first mode in the second subframe. In one aspect, the interference signal may appear in the first portion of the first symbol. In one aspect, the interference signal may be an in-band signal caused by a third-order intermodulation product from at least two OOB signals.

[0124] In another example, when the output of the interference detection circuit indicates that an interference signal has not been detected and (ii) a predetermined condition is not satisfied, the determination (in block 1604) may be to operate the receiver in the first mode in the second subframe. The predetermined condition may include a number of subframes in which no interference signal is detected that is greater than a threshold.

[0125] In another example, when (i) the output of the interference detection circuit indicates that an interference signal has not been detected and (ii) a predetermined condition is satisfied, the determination (in block 1604) may be to operate the receiver in the second mode in the second subframe. The predetermined condition may include a number of subframes in which no interference signal is detected that is greater than a threshold.

[0126] In one aspect, controlling the receiver (in block 1606) to operate in the first mode or the second mode includes: operating the receiver in the second mode for at least a first symbol of the second subframe. For example, in one aspect, operation 1600 may also include (i) detecting an amount of energy of the received signal during a first symbol of the second subframe, and (ii) selecting a gain state of the received signal from a plurality of gain states based on the amount of energy. In this aspect, after the first symbol of the second subframe, operation 1600 may also include (i) switching from operating the receiver in the second mode to operating the receiver in the first mode when the selected gain state does not satisfy a predetermined condition, or (ii) operating the receiver in the second mode for a first set of symbols including the first symbol of the second subframe when the selected gain state satisfies the predetermined condition. Operation 1600 may also include: performing at least one of an amplitude correction or a phase correction when switching from operating the receiver in the second mode to operating the receiver in the first mode.

[0127] In one aspect, operation 1600 may also include: during a second symbol of a second subframe outside of a first symbol set of the second subframe, (i) determining whether to operate the receiver in the first mode or the second mode in a third subframe based at least in part on an output of an interference detection circuit in the second symbol of the second subframe, and (ii) controlling the receiver to operate in the first mode or the second mode in the third subframe based on the determination during the second symbol of the second subframe. In one example, when the output of the interference detection circuit indicates that an interference signal is detected, the determination may be to operate the receiver in the first mode in the third subframe. In this example, the detection of the interference signal may occur in a symbol in the first symbol set of the second subframe. In another example, when the output of the interference detection circuit indicates that an interference signal has not been detected, the determination may be to operate the receiver in the second mode in the third subframe.

[0128] In one aspect, operating the receiver in a first mode (e.g., filter mode) may include filtering the received signal via a filter (e.g., filter 340 such as a BPF) prior to amplifying the received signal (e.g., via LNA 324). In one aspect, operating the receiver in a second mode (e.g., bypass mode) may include bypassing the filter (e.g., filter 340 such as a BPF) prior to amplifying the received signal (e.g., via LNA 324).

[0129] Example AGC for C-V2X in filter mode or bypass mode based on RF interference detection and V2X signal decoding

[0130] As mentioned herein, certain aspects may allow a wireless receiver to switch between (i) operating in a filter mode in the RX path and (ii) operating in a bypass mode in the RX path, depending on whether an interfering signal is present to the wireless receiver. However, in some cases, the RF interference detection circuitry in the RX RF receiver front end may not be able to distinguish between OOB interfering signals and in-band signals (e.g., in-band C-V2X signals). In these cases, a V2X signal from a nearby UE may cause the wireless receiver to switch to a filter mode in the RX path and remain in the filter mode for a long period of time in order to avoid the risk of subframe corruption (e.g., assuming that activation of the interference detection circuitry is associated with actual interference).

[0131] To address this issue, certain aspects described herein may enable a wireless receiver to perform C-V2X signal detection in order to determine whether a switch from a bypass mode to a filter mode in an RX path is due to detection of a V2X signal or an OOB interference signal. As described below, certain aspects define at least one software (SFW) interface bit (e.g., SFW-V2X bit, SFW-J bit) for indicating whether a switch from a bypass mode to a filter mode in an RX path is due to detection of a V2X signal (SFW-V2X bit) or an OOB interference signal (SFW-J bit).

[0132] In one aspect, the value of the SFW-V2X bit may be based on at least one of a cyclic redundancy check (CRC) and an in-band received signal strength indicator (RSSI) measurement. In one aspect, the in-band RSSI of the received signal may be compared to a predefined threshold associated with RF interference detection, and the SFW-V2X bit may be activated when the in-band RSSI exceeds the predefined threshold. The SFW-V2X bit may be provided after a predetermined amount of time (e.g., two subframes) has passed after a transition from a bypass mode to a filter mode in the RX path.

[0133] In some aspects, after the controller switches to operating in filter mode in the RX path, the controller may check the SFW-V2X bit to determine whether the switch to filter mode is due to a V2X signal. If the SFW-V2X bit is activated (e.g., indicating that the switch is due to a V2X signal), the controller may switch back to bypass mode in the RX path within a predetermined amount of time (e.g., two subframes). On the other hand, if the SFW-V2X bit is not activated (e.g., indicating that the switch is not due to a V2X signal), the controller may continue to operate in filter mode in the RX path. By enabling the controller to quickly (e.g., within two subframes) switch to bypass mode in the RX path when the SFW-V2X bit is activated (e.g., SFW-V2X bit = 1), the various aspects described herein can prevent the receiver front end from staying in filter mode for a significant amount of time in the presence of a strong V2X signal at the receiver.

[0134] In some aspects, the controller can also enforce a filter mode in the RX path based on WiFi detection by activating another SFW interface bit associated with WiFi detection (eg, the SFW-J bit).

[0135] In some aspects, if no interference signal is identified in both the main RX chain and the diversity RX chain, the controller can switch both RX chains from the filter mode to the bypass mode. Similarly, if one of the RX chains (e.g., the main RX chain or the diversity RX chain) is attacked by interference, the controller can switch all RX chains to the filter mode.

[0136] Fig.17 A flow chart of a method 1700 for performing “fast” AGC on a receiver front end (e.g., receiver front end 1000) based on RF interference signal detection and V2X signal detection in accordance with certain aspects of the present disclosure is shown. The method 1700 may be controlled by a controller (e.g., controller 336).

[0137] Method 1700 may be entered at box 1750, where the controller configures the receiver front end to operate in a filter mode (e.g., BPF mode) in the RX path. As part of configuring the receiver front end to operate in the filter mode in the RX path, the controller may set an interference counter (CNTR-J) to 1000 (or some other initial value) and may set a bypass counter (Bypass_SF) to 2000 (or some other initial value). The interference counter may be used to track the number of times an interfering signal has not been detected in a symbol of a subframe (e.g., symbol 13). The bypass counter may be used to track the amount of time the RX path has been in bypass mode. When the receiver front end is configured to operate in filter mode, the controller may use a set of gains and switching points associated with the filter mode (e.g., Figure 7 700 shown in FIG.

[0138] At block 1702, in symbol 0 of a subframe, the controller sets the DC correction value (K) to 1 / 0 and sets the gain to G1. At block 1704, in symbol 0 of a subframe, the controller reads the WBEE and selects a gain state from a set of gain states based on the WBEE. The operations in blocks 1702 and 1704 may be performed using Figure 7 This is performed with the gain states shown in Table 700. At block 1706, the controller sets the DC correction value (K) to 4 / 3 at some point during symbols 1 to 12 of the subframe.

[0139] At block 1708, during symbol 13 of the subframe, the controller updates the DC correction value (K) to 6 / 5. At block 1710, the controller configures the RX path to operate in bypass mode and reads the state of the jammer detection circuitry (eg, logic signal 1108).

[0140] At block 1712, the controller determines whether the state of the interference detection circuitry is "1" or "0" (e.g., whether the logic signal 1108 is "1" or "0"). If the state of the interference detection circuitry is "1", the controller configures the receiver front end to continue operating in filter mode in the RX path for subsequent subframes. After determining that the state of the interference detection circuitry is "1" in block 1712, the controller may or may not update the DC-LUT (block 1764). On the other hand, if the state of the interference detection circuitry is "0", the controller determines whether the SFW-J bit is activated (e.g., SFW-J bit = 1) (block 1714). If the SFW-J bit is activated, the controller configures the receiver front end to continue operating in filter mode in the RX path for subsequent subframes. If the SFW-J bit is not activated, the controller updates the DC-LUT (block 1716).

[0141] At block 1718, the controller determines whether a bypass counter (e.g., Bypass_SF) is greater than 2. If at block 1718, the controller determines that the bypass counter is greater than 2, the controller determines whether the interference counter is equal to 0 (block 1720). If the interference counter is not equal to 0, the controller configures the receiver front end to operate in filter mode in the RX path for subsequent subframes. On the other hand, if the interference counter is equal to 0, the controller proceeds to 1760, where the controller configures the receiver front end to operate in bypass mode in the RX path for subsequent subframes.

[0142] If at block 1718, the controller determines that the bypass counter is not greater than 2, the controller updates (e.g., decrements) the bypass counter (e.g., Bypass_SF=Bypass_SF-1) (block 1722), and updates (e.g., decrements) the interference counter (e.g., CNTR-J=CNTR-J-1) (block 1724). At block 1726, the controller determines whether the interference counter is equal to 0. If the interference counter is not equal to 0, the controller configures the receiver front end to operate in filter mode in the RX path for subsequent subframes. If the interference counter is equal to 0, the controller proceeds to block 1728, where the controller determines whether the bypass counter is equal to 0.

[0143] If at block 1728, the controller determines that the bypass counter is not equal to 0, the controller configures the receiver front end to operate in filter mode in the RX path for subsequent subframes. If at block 1728, the controller determines that the bypass counter is equal to 0, the controller determines whether the SFW-V2X bit is activated (e.g., SFW-V2X=1) (block 1730). If the SFW-V2X bit is not activated, the controller updates (e.g., resets) the interference counter and the bypass counter (e.g., CNTR-J=1000 and Bypass_SF=2000) (block 1732). On the other hand, if the SFW-V2X bit is activated, the controller configures the receiver front end to operate in bypass mode in the RX path for subsequent subframes (1760).

[0144] When the receiver front end is configured to operate in bypass mode, the controller may use a set of gains and switching points associated with the bypass mode (e.g., Fig.13 1300 shown in FIG. 1300 ). Except that blocks 1736 and 1738 are used Fig.13 The operations in blocks 1736 and 1738 are similar to the operations in blocks 1702 and 1704, respectively, except that the selected gain state is performed for the gain state shown in Table 1300 of FIG. 1740. At block 1740, the controller determines whether the selected gain state is greater than G1. If so, the controller matches the gain state selection with the filter mode (block 1734) and proceeds to block 1706. If the selected gain state is not greater than G1, the controller updates the DC correction value to K=4 / 3 at some point during symbols 1 to 12 (block 1742), and updates the DC correction value to K=6 / 5 at some point during symbol 13 (block 1744).

[0145] At block 1746, the controller reads the state of the jammer detection circuitry in symbol 13. At block 1752, the controller determines whether the state of the jammer detection circuitry is "1" or "0". If the state of the jammer detection circuitry is "0", the controller determines whether the SFW_J bit is equal to 1 (block 1756). If the SFW_J bit is not equal to 1, the controller updates the DC-LUT (block 1758) and configures the receiver front end to continue operating in bypass mode in the RX path for subsequent subframes.

[0146] If the state of the jammer detection circuit is "1", the controller avoids updating the DC-LUT (block 1754), updates the bypass counter (e.g., Bypass_SF=2) and the jammer counter (e.g., CNTR-J=2) (block 1766), and configures the receiver front end to operate in filter mode in the RX path for subsequent subframes. If at block 1756, the SFW_J bit is equal to 1, the controller proceeds to block 1754.

[0147] Note that while the method 1700 describes setting the interference counter to 1000 and decrementing the interference counter until the counter reaches 0, in some aspects the method 1700 may also be implemented by setting the interference counter to 0 and incrementing the interference counter until the counter reaches a threshold value (e.g., 1000). Similarly, while the method 1700 describes setting the bypass counter to 2000 and decrementing the bypass counter until the counter reaches 0, in some aspects the method 1700 may also be implemented by setting the bypass counter to 0 and incrementing the bypass counter until the counter reaches a threshold value (e.g., 2000).

[0148] In some cases, there may be some challenges in performing interference detection and DC calibration in bypass mode. For example, when performing DC calibration in bypass mode, the controller may obtain incorrect DC calibration values ​​in the presence of interference. In particular, when the receiver is in bypass mode, any interference detected within symbols 0 to 13 of a subframe may corrupt the DC calibration. If the interference detected in symbols 0 to 13 of a subframe disappears in a subsequent subframe, the incorrect DC calibration value may still be used for the subsequent subframe, resulting in an incorrect AGC decision. In addition, in some cases, the controller may not have enough time in symbol 13 of a subframe to (i) fine-tune the DC calibration, (ii) read the state of the RF interference detection circuit system, and (iii) switch from bypass mode to filter mode (in the case where the state of the RF interference detection circuit system indicates an interference signal (e.g., JDET=1)) without updating the DC LUT.

[0149] To address this issue, various aspects described herein provide techniques for performing DC calibration in filter mode (rather than bypass mode) and reading the state of the interference detection circuit system in bypass mode (rather than filter mode). Certain aspects define a DC calibration counter (e.g., CAL_CNTR) that can be used to indicate the time when the DC calibration was last performed during symbol 13. When the DC calibration counter expires, the DC calibration can be performed during filter mode.

[0150] More specifically, in some aspects, the controller can be configured to avoid reading the state of the interference detection circuit system when the receiver is operating in filter mode. Alternatively, the controller can switch to bypass mode based on the subframe counter (SF_CNTR). For example, when the subframe counter expires, the controller can configure the receiver to operate in bypass mode. Once an interference signal is detected in bypass mode, the controller can switch the receiver to operate in filter mode within a predetermined amount of time (e.g., a preconfigured subframe counter time, such as 2000).

[0151] When the receiver is in filter mode, the controller can continuously update the DC calibration based on the GS selected for the AGC. In addition, a DC calibration counter (CAL_CNTR) can be used to track the amount of time that has passed since the last DC calibration in symbol 13. When CAL_CNTR expires, the controller can perform a DC calibration for one or more gain states in symbol 13. In some cases, if the receiver is operating in bypass mode when CAL_CNTR expires, the controller can configure the receiver to switch to operate in filter mode, perform a DC calibration on one or more gain states in symbol 13 (when the receiver is in filter mode), and then configure the receiver to switch to operate in bypass mode. If the receiver is operating in filter mode when CAL_CNTR expires, the controller can perform a DC calibration on one or more gain states in symbol 13 (when the receiver is in filter mode).

[0152] When switching from bypass mode to filter mode, once the controller determines that the state of the interference detection circuit system indicates that an interference signal has been detected (e.g., JDET=1), the controller can set the bypass counter (Bypass_SF) to 2 subframes and check the state of the SFW-V2X bit in filter mode. If the state of the SFW-V2X bit is activated (e.g., SFW-V2X=1), the controller can configure the receiver to switch to operate in bypass mode. If the state of the SFW-V2X bit is deactivated (e.g., SFW-V2X=0), the controller can configure the receiver to stay in filter mode for a predetermined amount of time (e.g., the controller can set SF_CNTR to 2000 because the interference is OOB interference, not in-band V2X interference).

[0153] Fig.18 A flow chart of a method 1800 for performing “fast” AGC on a receiver front end (e.g., receiver front end 1000) based on RF interference signal detection and V2X signal detection in accordance with certain aspects of the present disclosure is shown. The method 1800 may be controlled by a controller (e.g., controller 336).

[0154] Method 1800 may be entered at box 1850, where the controller configures the receiver front end to operate in a filter mode (e.g., BPF mode) in the RX path. As part of configuring the receiver front end to operate in the filter mode in the RX path, the controller may set a DC calibration counter (CAL_CNTR) to 1000 (or some other initial value), may set a subframe counter (SF_CNTR) to 2000 (or some other initial value), and may set a bypass counter (Bypass_SF) to 2000 (or some other initial value). The controller may also set an initial gain state calibration (GS_CAL) to an initial value (e.g., GS_CAL=7). When the receiver front end is configured to operate in the filter mode, the controller may use a set of gains and switching points associated with the filter mode (e.g., Figure 7 700 shown in FIG.

[0155] At block 1802, in symbol 0 of a subframe, the controller sets the DC correction value (K) to 1 / 0 and sets the gain to G1. At block 1804, in symbol 0 of a subframe, the controller reads the WBEE and selects a gain state from a set of gain states based on the WBEE. Figure 7 The operations in blocks 1802 and 1804 are performed using the gain states shown in table 700. At block 1806, the controller sets the DC correction value (K) to 4 / 3 at a point in time during symbols 1 to 12 of the subframe.

[0156] At block 1808, during symbol 13 of the subframe, the controller performs a DC calibration. At block 1810, the controller updates a bypass counter (e.g., Bypass_SF=Bypass_SF-1). At block 1820, the controller determines whether the bypass counter is equal to 0. If the bypass counter is equal to 0, the method proceeds to block 1822. If the bypass counter is not equal to 0, the method proceeds to block 1824.

[0157] At block 1822, the controller determines whether the SFW-V2X bit is activated (e.g., SFW-V2X=1). If the SFW-V2X bit is not activated, the method proceeds to block 1850. If the SFW-V2X bit is activated, the method proceeds to block 1860, where the controller configures the receiver to operate in bypass mode in the RX path for subsequent subframes.

[0158] At block 1824, the controller determines whether the subframe counter (SF_CNTR) is equal to 0. If the subframe counter is equal to 0, the controller proceeds to block 1860. If the subframe counter is not equal to 0, the controller determines whether the DC calibration counter (CAL_CNTR) is equal to 0 (block 1826). If the DC calibration counter is not equal to 0, the controller configures the receiver to continue operating in filter mode in the RX path for subsequent subframes. On the other hand, if the DC calibration is equal to 0, during symbol 13 of the subframe, the controller updates the DC correction value (K) to 6 / 5 and sets the gain state selection to GS_CAL (block 1828). At block 1830, the controller updates GS_CAL (e.g., GS_CAL=GS_CAL-1).

[0159] At block 1832, the controller determines whether GS_CAL is equal to 0. If GS_CAL is not equal to 0, the controller sets the DC calibration counter (CAL_CNTR) to 0 (block 1834) and configures the receiver to continue operating in filter mode in the RX path for subsequent subframes. If the controller determines that GS_CAL is equal to 0, the controller sets the DC calibration counter (CAL_CNTR) to 500 (block 1836) and configures the receiver to continue operating in filter mode in the RX path for subsequent subframes.

[0160] When the receiver front end is configured to operate in bypass mode (block 1860), the controller may use a set of gains and switching points associated with the bypass mode (e.g., Fig.13 1300 shown in FIG. 1300 ). At block 1838, in symbol 0 of the subframe, the controller updates the DC correction value (K) based on the DC-LUT and sets the gain to G1. At block 1840, in symbol 0 of the subframe, the controller reads the WBEE and selects a gain state from a set of gain states based on the WBEE. Fig.13 The operations in blocks 1838 and 1840 are performed using the gain states shown in Table 1300 .

[0161] At block 1842, the controller determines whether the selected gain state is greater than G1. If so, the controller matches the gain state selection to the filter mode (block 1844), and the method proceeds to block 1806. If the selected gain state is not greater than G1, the controller updates the DC correction value based on the DC-LUT at some point during symbols 1 to 12 (block 1846).

[0162] At block 1848, the controller reads the state of the jammer detection circuitry in symbol 13. At block 1852, the controller determines whether the state of the jammer detection circuitry is "1" or "0". If the state of the jammer detection circuitry is "0", the controller determines whether the calibration counter (CAL_CNTR) is equal to 0 (block 1854). If the state of the jammer detection circuitry is "1", the controller sets the subframe counter (SF_CNTR) to 2 and the bypass counter (Bypass_SF) to 2 (block 1862), and configures the receiver to operate in filter mode in the RX path.

[0163] If at block 1854, the calibration counter is equal to zero, the method proceeds to block 1862. If at block 1854, the calibration counter is not equal to zero, the controller configures the receiver to continue operating in bypass mode for subsequent subframes.

[0164] Example Operation

[0165] Fig.19 is a flow diagram of example operations 1900 for operating a receiver (eg, the RX path 1004 of the receiver) in a filter mode and a bypass mode in accordance with certain aspects of the present disclosure.

[0166] Operations 1900 may generally involve, at block 1902 , operating a receiver (eg, RX path 1004 ) in a first mode (eg, filter mode) during a first subframe (eg, subframe N−1).

[0167] Operations 1900 also involve, at block 1904, determining whether to operate the receiver in a first mode or a second mode (eg, bypass mode) in a second subframe (eg, subframe N) based at least in part on the first counter (eg, SF_CNTR).

[0168] Operations 1900 also include, at block 1906, controlling the receiver to operate in the first mode or the second mode in the second subframe based on the determination.

[0169] In one aspect, operation 1900 further includes performing DC calibration in a first symbol (e.g., symbol 13) of a first subframe. The DC calibration may be performed based on at least one of: (i) a gain state selection or (ii) a second counter (e.g., a DC calibration counter (CAL_CNTR)). For example, the controller may perform the DC calibration after performing a gain state selection (e.g., block 1808 of method 1800) and / or after the second counter has expired (e.g., block 1828 of method 1800).

[0170] In one aspect, when the first counter is equal to a predetermined value (e.g., SF_CNTR=0), it is determined (in block 1904) to operate the receiver in the second mode during the second subframe. In one aspect, when the first counter is not equal to the predetermined value (e.g., SF_CNTR !=0), it is determined (in block 1904) to operate the receiver in the first mode during the second subframe.

[0171] In one aspect, controlling the receiver (in block 1906) to operate in the first mode or the second mode includes operating the receiver in the second mode for at least a first set of symbols (e.g., symbols 1-12) of a second subframe. In one aspect, operation 1900 may also include determining an output of an interference detection circuit of the receiver in the second symbol during a second symbol (e.g., symbol 13) of the second subframe outside of the first set of symbols of the second subframe. In this aspect, operation 1900 may also include (i) determining to switch to operating the receiver in the first mode for a third subframe when the output of the interference detection circuit indicates an interference signal, or (ii) determining to continue operating the receiver in the second mode for the third subframe when the output of the interference detection circuit does not indicate an interference signal.

[0172] Example aspects

[0173] In addition to the above-mentioned various aspects, specific combinations of the various aspects are also within the scope of the present disclosure, some of which are as follows:

[0174] Aspect 1: A method for wireless communication, the method comprising: operating a receiver in a first mode during a first symbol set of a first subframe; during a first symbol outside the first symbol set of the first subframe, determining whether to operate the receiver in the first mode or the second mode in a second subframe based at least in part on an output of an interference detection circuit of the receiver in the first symbol; and based on the determination, controlling the receiver to operate in the first mode or the second mode in the second subframe.

[0175] Aspect 2: The method according to aspect 1 further comprises: operating a transmitter, wherein the transmitter is configured to avoid transmitting during the first symbol.

[0176] Aspect 3: The method according to aspect 1 or 2, wherein the first symbol is after the first set of symbols of the first subframe.

[0177] Aspect 4: The method according to any one of Aspects 1 to 3, wherein the receiver is configured to receive a cellular vehicle-to-everything (C-V2X) reception signal.

[0178] Aspect 5: The method according to any one of Aspects 1 to 4 further includes: for a first part of the first symbol, switching from operating the receiver in the first mode to operating the receiver in the second mode, wherein the determination of whether to operate the receiver in the first mode or the second mode in the second subframe is based on the output of the interference detection circuit in the first part of the first symbol.

[0179] Aspect 6: The method of aspect 5, wherein when the output of the interference detection circuit indicates that a WiFi signal has been detected, the determination is to operate the receiver in the first mode in the second subframe.

[0180] Aspect 7: The method of aspect 5, wherein when the output of the interference detection circuit indicates detection of an interference signal, the determination is to operate the receiver in the first mode in the second subframe.

[0181] Aspect 8: The method according to aspect 7, wherein the detection of the interfering signal occurs in the first portion of the first symbol.

[0182] Aspect 9: The method according to aspect 7 or 8, wherein the interference signal is an in-band signal caused by a third-order intermodulation product of at least two out-band signals.

[0183] Aspect 10: The method according to any one of Aspects 7 to 9 further includes: after determining to operate the receiver in the first mode in the second subframe, when the output of the interference detection circuit indicates that the detection of the interference signal is caused by an in-band received signal, determining to switch to operating the receiver in the second mode for the third subframe.

[0184] Aspect 11: The method according to Aspect 10, wherein the in-band received signal is a cellular vehicle-to-everything (C-V2X) received signal.

[0185] Aspect 12: A method according to any one of Aspects 1 to 11, wherein, when (i) the output indication of the interference detection circuit indicates that an interference signal has not been detected and (ii) a predetermined condition is not met, the determination is to operate the receiver in the first mode in the second subframe.

[0186] Aspect 13: The method according to Aspect 12, wherein the predetermined condition includes that the number of subframes in which no interference signal is detected is greater than a threshold.

[0187] Aspect 14: A method according to any one of Aspects 1 to 11, wherein, when (i) the output indication of the interference detection circuit indicates that no interference signal has been detected and (ii) a predetermined condition is met, the determination is to operate the receiver in the second mode in the second subframe.

[0188] Aspect 15: The method according to Aspect 14, wherein the predetermined condition includes that the number of subframes in which no interference signal is detected is greater than a threshold.

[0189] Aspect 16: The method according to any one of Aspects 1 to 5 and 14 to 15, wherein controlling the receiver to operate in the first mode or the second mode comprises: operating the receiver in the second mode for at least the first symbol of the second subframe.

[0190] Aspect 17: The method according to Aspect 16 also includes: detecting the amount of energy of the received signal during the first symbol of the second subframe; and selecting a gain state for the received signal from a plurality of gain states based on the energy amount.

[0191] Aspect 18: The method according to Aspect 17 further comprises: after the first symbol of the second subframe, when the selected gain state does not satisfy a predetermined condition, switching from operating the receiver in the second mode to operating the receiver in the first mode.

[0192] Aspect 19: The method according to aspect 18 further comprises: performing at least one of amplitude correction or phase correction when switching from operating the receiver in the second mode to operating the receiver in the first mode.

[0193] Aspect 20: The method according to aspect 17 further comprises: when the selected gain state satisfies a predetermined condition, operating the receiver in the second mode for a first set of symbols including the first symbol of the second subframe.

[0194] Aspect 21: The method according to Aspect 20 further includes: during a second symbol of the second subframe outside the first symbol set of the second subframe, determining whether to operate the receiver in the first mode or the second mode in a third subframe based at least in part on the output of the interference detection circuit in the second symbol of the second subframe; and controlling the receiver to operate in the first mode or the second mode in the third subframe based on the determination during the second symbol of the second subframe.

[0195] Aspect 22: The method of aspect 21, wherein when the output of the interference detection circuit indicates detection of an interference signal, the determination is to operate the receiver in the first mode in the third subframe.

[0196] Aspect 23: The method according to aspect 22, wherein the detection of the interference signal occurs in a symbol in the first set of symbols in the second subframe.

[0197] Aspect 24: The method of aspect 21, wherein when the output of the interference detection circuit indicates that an interference signal has not been detected, the determination is to operate the receiver in the second mode in the third subframe.

[0198] Aspect 25: The method according to any one of aspects 1 to 24, wherein operating the receiver in the first mode comprises: filtering the received signal via a filter before amplifying the received signal.

[0199] Aspect 26: The method according to any one of aspects 1 to 25, wherein operating the receiver in the second mode comprises: bypassing a filter before amplifying the received signal.

[0200] Aspect 27: A method for wireless communication, the method comprising: operating a receiver in a first mode during a first subframe; determining whether to operate the receiver in the first mode or the second mode in a second subframe based at least in part on a first counter; and based on the determination, controlling the receiver to operate in the first mode or the second mode in the second subframe.

[0201] Aspect 28: The method according to aspect 27 further includes: performing DC calibration in the first symbol of the first subframe.

[0202] Aspect 29: The method according to aspect 28, wherein the DC calibration is performed based on at least one of: (i) gain state selection or (ii) a second counter.

[0203] Aspect 30: The method according to any one of aspects 27 to 29, wherein when the first counter is equal to a predetermined value, the determination is to operate the receiver in the second mode during the second subframe.

[0204] Aspect 31: The method according to any one of aspects 27 to 29, wherein when the first counter is not equal to a predetermined value, the determination is to operate the receiver in the first mode during the first subframe.

[0205] Aspect 32: A method according to any one of Aspects 27 to 30, wherein controlling the receiver to operate in the first mode or the second mode includes: operating the receiver in the second mode for at least a first set of symbols of the second subframe.

[0206] Aspect 33: The method according to any one of Aspects 27 to 30 and 32 further includes: during a second symbol of the second subframe outside the first set of symbols of the second subframe, determining the output of the interference detection circuit of the receiver in the second symbol.

[0207] Aspect 34: The method according to Aspect 34 further includes: when the output of the interference detection circuit indicates an interference signal, determining to switch to operating the receiver in the first mode for the third subframe, or (ii) when the output of the interference detection circuit does not indicate an interference signal, determining to continue operating the receiver in the second mode for the third subframe.

[0208] Aspect 35: A wireless device comprising: a receiver including an interference detection circuit; at least one processor coupled to the receiver; and a memory coupled to the at least one processor and storing computer-executable instructions, which, when executed by the at least one processor, perform a method according to any one of Aspects 1-34.

[0209] Aspect 36: An apparatus comprising means for performing the method according to any one of aspects 1-34.

[0210] Aspect 37: A non-transitory computer-readable medium comprising executable instructions, which, when executed by a processor of a device, cause the device to perform the method according to any one of aspects 1-34.

[0211] Aspect 38: A computer program product embodied on a computer-readable storage medium, comprising code for executing the method according to any one of aspects 1-34.

[0212] Additional Considerations

[0213] The following description provides examples and does not limit the scope, applicability or examples set forth in the claims. Without departing from the scope of the present disclosure, the functions and arrangements of the elements discussed may be changed. Each example may ignore, replace or add each process or component as appropriate. For example, the method described may be performed in an order different from the order described, and various steps may be added, omitted or combined. In addition, the features described for some examples may be combined in some other examples. For example, any number of aspects set forth herein may be used to implement a device or practice method. In addition, the scope of the present disclosure is intended to cover such devices or methods practiced using other structures, functions, or structures and functions other than or different from the various aspects of the present disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of the claims. The word "exemplary" is used herein to mean "used as an example, instance or illustration". Any aspect described as "exemplary" herein is not necessarily interpreted as being preferred over or having advantages over other aspects.

[0214] The various operations of the method described above can be performed by any appropriate unit capable of performing the corresponding function. The unit may include various hardware and / or software components and / or modules, including but not limited to circuits, application specific integrated circuits (ASICs) or processors. Generally, in the case of the operations shown in the figure, those operations may have corresponding paired functional unit components. For example, a unit for receiving a signal may include, for example, a receiver (e.g., a receiver front end 1000), an antenna (e.g., an antenna 306), etc. A unit for detecting the presence of an interference signal may include, for example, an interference detection circuit (e.g., an interference detection circuit 1102, an interference detection circuit 1106, a logic gate 1104), etc. A unit for determining and a unit for controlling may include, for example, one or more processors (e.g., a controller 336, a receiving processor 258, etc.), etc.

[0215] As used herein, a phrase referring to "at least one of" a list of items refers to any combination of those items, including single members. For example, "at least one of a, b, or c" is intended to cover a, b, c, ab, ac, bc, and abc, as well as any combination with plural numbers of the same elements (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc or any other ordering of a, b, and c).

[0216] The method disclosed herein includes one or more steps or actions for implementing the described method. Without departing from the scope of the claims, the method steps and / or actions can be interchangeable with each other. In other words, unless a specific order of steps or actions is specified, the order and / or use of specific steps and / or actions can be modified without departing from the scope of the claims.

[0217] It is to be understood that the claims are not limited to the precise configuration and components shown above. Various modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.

Claims

1. A method for wireless communication, the method comprising: operating the receiver in a first mode during a first set of symbols of a first subframe; during a first symbol of the first subframe outside of the first set of symbols, determining whether to operate the receiver in the first mode or the second mode in a second subframe based at least in part on an output of an interference detection circuit of the receiver in the first symbol; as well as According to the determination, the receiver is controlled to operate in the first mode or the second mode in the second subframe.

2. The method according to claim 1, further comprising: Operating a transmitter, wherein the transmitter is configured to refrain from transmitting during the first symbol.

3. The method according to claim 1, wherein: The first symbol follows the first set of symbols of the first subframe.

4. The method according to claim 1, wherein: The receiver is configured to receive a cellular vehicle-to-everything (C-V2X) reception signal.

5. The method according to claim 1, further comprising: Switching from operating the receiver in the first mode to operating the receiver in the second mode for a first portion of the first symbol, wherein the determination of whether to operate the receiver in the first mode or the second mode in the second subframe is based on the output of the interference detection circuit in the first portion of the first symbol.

6. The method according to claim 5, wherein: When the output of the interference detection circuit indicates that a WiFi signal has been detected, the determination is to operate the receiver in the first mode in the second subframe.

7. The method according to claim 5, wherein: When the output of the interference detection circuit indicates detection of an interference signal, the determination is to operate the receiver in the first mode in the second subframe.

8. The method according to claim 7, wherein: The detection of the interfering signal occurs in the first portion of the first symbol.

9. The method according to claim 7, wherein: The interference signal is an in-band signal caused by a third-order intermodulation product of at least two out-band signals.

10. The method according to claim 7, further comprising: After determining to operate the receiver in the first mode in the second subframe, determining to switch to operating the receiver in the second mode for a third subframe when the output of the interference detection circuit indicates that the detection of the interference signal is caused by an in-band received signal.

11. The method according to claim 10, wherein: The in-band receive signal is a cellular vehicle-to-everything (C-V2X) receive signal.

12. The method according to claim 5, wherein: The determination is to operate the receiver in the first mode in the second subframe when (i) the output of the interference detection circuit indicates that an interference signal has not been detected and (ii) a predetermined condition is not satisfied.

13. The method according to claim 12, wherein: The predetermined condition includes that the number of subframes in which no interference signal is detected is greater than a threshold.

14. The method according to claim 5, wherein: The determination is to operate the receiver in the second mode in the second subframe when (i) the output of the interference detection circuit indicates that an interference signal has not been detected and (ii) a predetermined condition is satisfied.

15. The method according to claim 14, wherein: The predetermined condition includes that the number of subframes in which no interference signal is detected is greater than a threshold.

16. The method according to claim 1, wherein: Controlling the receiver to operate in the first mode or the second mode includes operating the receiver in the second mode for at least a first symbol of the second subframe.

17. The method according to claim 16, further comprising: detecting an amount of energy of a received signal during the first symbol of the second subframe; as well as A gain state for the received signal is selected from a plurality of gain states based on the amount of energy.

18. The method according to claim 17, further comprising: After the first symbol of the second subframe, when the selected gain state does not satisfy a predetermined condition, switching from operating the receiver in the second mode to operating the receiver in the first mode.

19. The method according to claim 18, further comprising: When switching from operating the receiver in the second mode to operating the receiver in the first mode, at least one of an amplitude correction or a phase correction is performed.

20. The method of claim 17, further comprising: When the selected gain state satisfies a predetermined condition, the receiver is operated in the second mode for a first set of symbols including the first symbol of the second subframe.

21. The method according to claim 20, further comprising: determining, during a second symbol of the second subframe outside of the first set of symbols of the second subframe, whether to operate the receiver in the first mode or the second mode in a third subframe based at least in part on the output of the interference detection circuit in the second symbol of the second subframe; as well as The receiver is controlled to operate in the first mode or the second mode in the third subframe according to the determination during the second symbol of the second subframe.

22. The method according to claim 21, wherein: When the output of the interference detection circuit indicates detection of an interference signal, the determination is to operate the receiver in the first mode in the third subframe.

23. The method according to claim 22, wherein: The detection of the interfering signal occurs in a symbol in the first set of symbols in the second subframe.

24. The method according to claim 21, wherein: When the output of the interference detection circuit indicates that an interference signal has not been detected, the determination is to operate the receiver in the second mode in the third subframe.

25. The method of claim 1, wherein: Operating the receiver in the first mode includes filtering the received signal via a filter prior to amplifying the received signal.

26. The method of claim 1, wherein: Operating the receiver in the second mode includes bypassing a filter prior to amplifying the received signal.

27. A wireless device comprising: a receiver including an interference detection circuit; at least one processor coupled to the receiver; as well as a memory coupled to the at least one processor and storing computer executable instructions that, when executed by the at least one processor, perform operations comprising: operating the receiver in a first mode during a first set of symbols of a first subframe; determining, during a first symbol of the first subframe outside of the first set of symbols, whether to operate the receiver in the first mode or the second mode in a second subframe based at least in part on an output of the interference detection circuit in the first symbol; and According to the determination, the receiver is controlled to operate in the first mode or the second mode in the second subframe.

28. The wireless device of claim 27, wherein: The receiver includes a filter and an amplifier; as well as Controlling the receiver to operate in the first mode includes controlling the receiver to filter the received signal via the filter before amplifying the received signal via the amplifier.

29. The wireless device of claim 27, wherein: The receiver includes a filter and an amplifier; as well as Controlling the receiver to operate in the second mode includes controlling the receiver to bypass the filter before amplifying the received signal via the amplifier.

30. An apparatus comprising: means for receiving a signal in a first mode during a first set of symbols of a first subframe; means for detecting the presence of an interfering signal during a first symbol of the first subframe that is outside of the first set of symbols; means for determining whether to operate the means for receiving in the first mode or the second mode in a second subframe based at least in part on an output of the means for detecting in the first symbol; as well as Means for controlling the means for receiving to operate in the first mode or the second mode in the second subframe according to the determination.

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