CN111902728B - Exchanging radar information using a side communication channel to improve multi-radar coexistence - Google Patents

Abstract

Methods, systems, and devices for wireless communications are described. In some systems, a radio signal may reach a receiving antenna at a user equipment through two or more paths, which may cause interference (e.g., destructive multipath interference, constructive multipath interference, etc.). To reduce interference, the user equipment may perform interference suppression, shaping, or both based on selecting a radar waveform pattern that varies across the chirp. In one aspect, a user equipment (e.g., a vehicle) may identify a waveform pattern selected by a nearby vehicle based on side channel or centralized signaling, and may suppress or shape interference by selecting waveform parameters based on this information. In one aspect, the pattern of waveform parameters is selected from a codebook of patterns. The selected mode may be broadcast to other vehicles using a side communication channel.

Description

Exchanging radar information using a side communication channel to improve multi-radar coexistence

Cross reference

This patent application claims the benefits of U.S. provisional patent application No.62/648,255, entitled "Using a Side-Communication Channel for Exchanging Radar Information to Improve Multi-Radar Coexistence( use side communication channel to exchange radar information to improve multi-radar coexistence, "filed by Gulati et al at 2018, 3, 26, and U.S. provisional patent application No.62/648,774, entitled "Using A Side-Communication Channel For Exchanging Radar Information To Improve Multi-Radar Coexistence( use side communication channel to exchange radar information to improve multi-radar coexistence," filed by Gulati et al at 2018, 3, 27, and U.S. patent application No.16/354,018, entitled "Using a Side-Communication Channel for Exchanging Radar Information to Improve Multi-Radar Coexistence( use side communication channel to exchange radar information to improve multi-radar coexistence, "filed by Gulati et al at 2019, 3, 14; each of which is assigned to the assignee of the present application.

Background

The following relates generally to radar target detection, wireless communication, and more particularly to utilizing a wireless communication system to improve performance of radar systems in multi-radar coexistence scenarios.

Radar systems are used for target detection by: the radio frequency waveform is transmitted and the reflected waveform received from the target is observed to estimate properties of the target such as the distance, velocity and angular position of the target. Radar systems are widely used for detection of aircraft, ships, vehicles, climate formations, topography, etc. Examples of transmitted radio frequency waveforms for use in radar systems may include Frequency Modulated Continuous Wave (FMCW), phase Modulated Continuous Wave (PMCW), and so on.

Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be able to support communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include Code Division Multiple Access (CDMA) systems, time Division Multiple Access (TDMA) systems, frequency Division Multiple Access (FDMA) systems, and Orthogonal Frequency Division Multiple Access (OFDMA) systems. A wireless multiple-access communication system may include several base stations, each supporting communication for multiple communication devices, which may include User Equipment (UEs), simultaneously.

Radar may be used as a sensor input in automobiles to enable Advanced Driver Assistance Systems (ADAS) and autopilot. However, radar transmissions from nearby vehicles may generate significant interference with the radar system and may degrade target detection performance.

SUMMARY

The present disclosure relates to methods, systems, devices, and apparatuses supporting the exchange of radar information using a side-communication (side-communication) channel. Methods, systems, devices, and apparatus may improve multi-radar coexistence in wireless communication systems.

A method implemented by a UE for suppressing interference to radar in a communication system is described. The method may include: selecting waveform parameters for transmitting a radar waveform, wherein the radar waveform comprises a set of chirps, and the selecting comprises changing the waveform parameters for at least one of the set of chirps; transmitting an indication of one or more selected waveform parameters over the communication system; and transmitting the radar waveform according to the selected waveform parameters.

An apparatus implemented by a UE for suppressing interference to radar in a communication system is described. The apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. The instructions are executable by the processor to cause the apparatus to: selecting waveform parameters for transmitting a radar waveform, wherein the radar waveform comprises a set of chirps, and the selecting comprises changing the waveform parameters for at least one of the set of chirps; transmitting an indication of one or more selected waveform parameters over the communication system; and transmitting the radar waveform according to the selected waveform parameters.

Another UE implemented device for suppressing interference to radar in a communication system is described. The apparatus may comprise means for: selecting waveform parameters for transmitting a radar waveform, wherein the radar waveform comprises a set of chirps, and the selecting comprises changing the waveform parameters for at least one of the set of chirps; transmitting an indication of one or more selected waveform parameters over the communication system; and transmitting the radar waveform according to the selected waveform parameters.

A non-transitory computer-readable medium storing code implemented by a UE for suppressing interference with radar in a communication system is described. The code may include instructions executable by the processor to: selecting waveform parameters for transmitting a radar waveform, wherein the radar waveform comprises a set of chirps, and the selecting comprises changing the waveform parameters for at least one of the set of chirps; transmitting an indication of one or more selected waveform parameters over the communication system; and transmitting the radar waveform according to the selected waveform parameters.

In some aspects of the methods, apparatus (devices) and non-transitory computer-readable media described herein, selecting waveform parameters may include operations, features, means or instructions for: a codeword is selected from a codebook comprising a set of codewords, wherein the codeword is indicative of a selected waveform parameter.

In some aspects of the methods, apparatus (devices) and non-transitory computer-readable media described herein, selecting waveform parameters may include operations, features, means or instructions for: identifying a set of codewords for additional UEs within a threshold distance; and varying the waveform parameters for the at least one chirp to have a uniform distribution over a range such that the distance between the selected codeword and the identified set of codewords can be maximized.

In some aspects of the methods, apparatus (means) and non-transitory computer-readable media described herein, transmitting the indication of the one or more selected waveform parameters may include operations, features, means or instructions for: the indication of the one or more selected waveform parameters is broadcast on one or more side communication channels between the UE and one or more additional UEs.

In some aspects of the methods, apparatus (means) and non-transitory computer-readable media described herein, transmitting the indication of the one or more selected waveform parameters may include operations, features, means or instructions for: the indication of the one or more selected waveform parameters is transmitted on an Uplink (UL) channel between the UE and a network entity.

Some aspects of the methods, apparatus (means) and non-transitory computer readable media described herein may further include operations, features, means, or instructions for: information of a set of codewords in use in the vicinity of the UE is received from a network entity.

Some aspects of the methods, apparatus (means) and non-transitory computer readable media described herein may further include operations, features, means, or instructions for: a beacon, an encoded discovery message, or a combination thereof is broadcast on one or more side communication channels between the UE and one or more additional UEs to indicate the location of the UE.

Some aspects of the methods, apparatus (means) and non-transitory computer readable media described herein may further include operations, features, means, or instructions for: information of a set of codewords used by the additional UE is received over one or more multi-sided communication channels between the UE and one or more additional UEs, wherein the waveform parameters can be changed based on the information of the set of codewords used by the additional UE.

Some aspects of the methods, apparatus (means) and non-transitory computer readable media described herein may further include operations, features, means, or instructions for: receiving a set of beacons, encoded discovery messages, or a combination thereof for the additional UE on the one or more side communication channels between the UE and the one or more additional UEs to indicate a location of the additional UE; and determining a set of proximity values for the additional UE relative to the UE, wherein the waveform parameter is changeable based on the set of proximity values for the additional UE.

In some aspects of the methods, apparatus (devices) and non-transitory computer-readable media described herein, the selected waveform parameters include a frequency range, a chirp duration, a frequency offset, or a combination thereof.

Some aspects of the methods, apparatus (means) and non-transitory computer readable media described herein may further include operations, features, means, or instructions for: identifying a range of interest of an interference source for the radar waveform; and setting a frequency offset of the radar waveform such that an interference peak of at least one interference source occurs outside the range of interest.

Some aspects of the methods, apparatus (means) and non-transitory computer readable media described herein may further include operations, features, means, or instructions for: one or more chirps of the radar waveform are phase encoded to avoid coherent superposition of the chirp with other radar waveforms in the communication system.

Brief Description of Drawings

Fig. 1 illustrates an example wireless network in accordance with aspects of the present disclosure.

Fig. 2 illustrates an example logical architecture of a distributed Radio Access Network (RAN) in accordance with aspects of the present disclosure.

Fig. 3 illustrates an example physical architecture of a distributed RAN in accordance with aspects of the present disclosure.

Fig. 4 illustrates example components of a base station and a User Equipment (UE) in a wireless communication system in accordance with aspects of the present disclosure.

Fig. 5A illustrates an example of a Downlink (DL) centric sub-frame according to aspects of the present disclosure.

Fig. 5B illustrates an example of an Uplink (UL) centric subframe according to aspects of the present disclosure.

Fig. 6A illustrates an example wireless communication system in accordance with aspects of the present disclosure.

Fig. 6B illustrates an example graph showing received power of direct and reflected signals with distance, in accordance with aspects of the present disclosure.

Fig. 7A and 7B illustrate frequency-time plots of Frequency Modulated Continuous Waves (FMCW) with different parameters according to aspects of the present disclosure. Fig. 7A illustrates the unchanged waveform parameters, while fig. 7B illustrates the change in the slope β and/or frequency offset f parameters.

Fig. 8 illustrates an FMCW system with received and transmitted ramp waveforms modulated with sawtooth chirp, according to aspects of the present disclosure.

Fig. 9 is a flow chart illustrating a method for implementing coexistence of multiple radar sources by a UE that may suppress radar interference in a communication system in accordance with aspects of the present disclosure.

Fig. 10 is a flow chart illustrating a method for implementing coexistence of multiple radar sources by a UE, the method comprising suppressing radar interference in a communication system, in accordance with aspects of the present disclosure.

Fig. 11 illustrates certain components that may be included within a base station.

Fig. 12 illustrates certain components that may be included within a wireless communication device.

Detailed Description

In some wireless communication systems, such as fifth generation (5G) New Radio (NR) systems, the transmission waveforms may include cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) and discrete fourier transform spread (DFT-S) OFDM.5G allows switching between CP-OFDM and DFT-S-OFDM on the Uplink (UL) to obtain the multiple-input multiple-output (MIMO) spatial multiplexing benefits of CP-OFDM and the link budget benefits of DFT-S-OFDM. With Long Term Evolution (LTE), orthogonal Frequency Division Multiple Access (OFDMA) communication signals may be used for Downlink (DL) communications, while single carrier frequency division multiple access (SC-FDMA) communication signals may be used for LTE UL communications. The DFT-s-OFDMA scheme spreads a set of data symbols (i.e., a sequence of data symbols) over the frequency domain, unlike the OFDMA scheme. In addition, the DFT-s-OFDMA scheme can greatly reduce a peak-to-average power ratio (PAPR) of a transmission signal compared to the OFDMA scheme. The DFT-s-OFDMA scheme may also be referred to as an SC-FDMA scheme.

The scalable OFDM multi-tone parameter design is another feature of 5G. Previous versions of LTE support a nearly fixed OFDM parameter design of fifteen (15) kilohertz (kHz) spacing between OFDM tones (commonly referred to as subcarriers) and carrier bandwidths of up to twenty (20) megahertz (MHz). Scalable OFDM parameter designs have been introduced in 5G to support various spectral bands/types and deployment models. For example, 5G NR can operate in a millimeter wave (mmW) band having a channel width (e.g., hundreds of MHz) wider than a bandwidth used in LTE. Furthermore, the OFDM subcarrier spacing may scale with channel width, and thus the Fast Fourier Transform (FFT) size may also scale so that processing complexity does not increase unnecessarily for a wider bandwidth. In the present application, parameter designs may refer to different values that may be taken by different features of the communication system, such as subcarrier spacing, cyclic Prefix (CP), symbol length, FFT size, transmission Time Interval (TTI), etc.

Also in 5G NR, cellular technology has been extended into unlicensed spectrum (e.g., both stand-alone and Licensed Assisted Access (LAA)). In addition, unlicensed spectrum may occupy frequencies up to sixty (60) gigahertz (GHz) (also known as mmW). The use of unlicensed bands provides increased capacity for communications in the system.

The first member of this technology family is called LTE unlicensed (LTE-U). By aggregating LTE in unlicensed spectrum with "anchor" channels in licensed spectrum, faster downloads may be achieved for clients. Further, LTE-U may share unlicensed spectrum fairly with Wi-Fi. This is advantageous because in the five (5) GHz unlicensed band where Wi-Fi devices are widely used, it is desirable for LTE-U to coexist with Wi-Fi. However, the LTE-U network may cause Radio Frequency (RF) interference to existing co-channel Wi-Fi devices. The goal of an LTE-U device may be to select a preferred operating channel and minimize interference to nearby Wi-Fi networks. However, if all available channels are occupied by Wi-Fi devices, the LTE-U Single Carrier (SC) device may operate on the same channel as Wi-Fi. To coordinate spectrum access between LTE-U and Wi-Fi, energy across an intended transmission band may be detected first. The Energy Detection (ED) mechanism informs the device of the ongoing transmissions by other nodes. Based on the ED information, the device decides whether the device should transmit on the intended transmission band. Wi-Fi devices may not backoff for LTE-U transmissions unless the interference level caused by the LTE-U transmissions is above the ED threshold (e.g., minus sixty-two (-62) decibel-milliwatts (dBm) at 20 MHz). Thus, if there is no appropriate coexistence mechanism, LTE-U transmissions may cause considerable interference to Wi-Fi networks relative to Wi-Fi transmissions.

LAA is another member of the unlicensed technology family. As with LTE-U, it may also use anchor channels in licensed spectrum. However, it would also add a "listen before talk" (LBT) operation to the LTE functionality.

The gating interval may be used to gain access to channels of the shared spectrum. The gating interval may determine the application of a contention-based protocol, such as the LBT protocol. The gating interval may indicate when a Clear Channel Assessment (CCA) is performed. It is determined by the CCA whether a channel of the shared unlicensed spectrum is available or in use. If the channel is "clear" for use, i.e., available, the gating interval may allow the transmitting device to use the channel. Access to the channel is typically granted within a predefined transmission interval. Thus, in the case of using unlicensed spectrum, a "listen before talk" procedure is performed before the message is transmitted. If the channel is not cleared for use, the device will not transmit on the channel.

Another member of the unlicensed technology family is LTE Wireless Local Area Network (WLAN) aggregation (LWA), which may utilize both LTE and Wi-Fi. Considering two channel conditions, the LWA may split a single data stream into two data streams, allowing both LTE and Wi-Fi channels to be used for applications. LTE signals may seamlessly use WLAN connections to increase capacity, rather than competing with Wi-Fi.

The last member of the unlicensed technology family is MulteFire. MulteFire opens new opportunities by operating fourth generation (4G) LTE technology only in unlicensed spectrum, such as global 5 GHz. Unlike LTE-U and LAA, multewire may support entities that do not have any access to licensed spectrum. Thus, it operates in unlicensed spectrum on a stand-alone basis (e.g., without any anchor channels in the licensed spectrum). Thus MulteFire is different from LTE-U, LAA and LWA because LTE-U, LAA and LWA aggregate unlicensed spectrum with anchors in licensed spectrum. MulteFire allows Wi-Fi like deployment without relying on licensed spectrum as an anchor service. The MulteFire network may include Access Points (APs) and/or base stations that communicate in an unlicensed radio frequency spectrum band (e.g., without a licensed anchor carrier).

Discovery Reference Signal (DRS) measurement timing configuration (DMTC) is a technology that allows MulteFire to transmit with minimal or reduced interference to other unlicensed technologies, including Wi-Fi. In addition, the periodicity of the signal found in MulteFire can be very sparse. This allows Multefire to occasionally access the channel, transmit discovery and control signals, and then vacate the channel. Since unlicensed spectrum is shared with other radios of similar or different wireless technology, the so-called LBT method may be applied for channel listening. LBT may include listening to the medium for a predefined minimum amount of time and back-off if the channel is busy. Thus, the initial Random Access (RA) procedure of the standalone LTE-U may involve a minimum number of transmissions with low latency, so that the number of LBT operations may be minimized or reduced, and the RA procedure may be completed quickly.

Using the DMTC window, the MulteFire algorithm can search and decode the reference signals from neighboring base stations in the unlicensed band to find which base station to select to serve the user. As a calling party moves past one base station, its User Equipment (UE) may send measurement reports to that base station, triggering a handover procedure and transferring the calling party (and all of its content and information) to the next base station.

Since LTE traditionally operates in licensed spectrum, while Wi-Fi operates in unlicensed bands, coexistence with Wi-Fi or other unlicensed technologies was not considered when designing LTE. Upon moving to the unlicensed world, the LTE waveform is modified and an algorithm is added to perform LBT. This may support the ability to share a channel with unlicensed incumbent systems (including Wi-Fi) by not immediately acquiring the channel and transmitting. Examples of the present disclosure support LBT and detection and transmission of Wi-Fi channels using beacon signals (WCUBS) to ensure coexistence with Wi-Fi neighbors.

MulteFire are designed to "listen" to transmissions of neighboring Wi-Fi base stations. MulteFire may first listen and autonomously make a decision to transmit when no other neighboring Wi-Fi is transmitting on the same channel (e.g., within a threshold range). This technique may ensure coexistence between MulteFire and Wi-Fi transmissions.

The third generation partnership project (3 GPP) and the European Telecommunications Standards Institute (ETSI) mandate LBT detection thresholds (e.g., minus seventy-two (-72) dBm LBT detection thresholds). The threshold may further help the wireless device avoid transmitting messages that interfere with Wi-Fi. The LBT design of MulteFire may be similar or identical to the standard defined in 3GPP for LAA/enhanced LAA (eLAA) and may follow ETSI rules.

Extended functionality for 5G involves the use of 5G NR spectrum sharing (NR-SS). The 5G NR-SS may enable enhancements, extensions and/or upgrades to spectrum sharing techniques introduced in LTE. These include LTE Wi-Fi aggregation (LWA), LAA, eLAA, citizen Broadband Radio Service (CBRS)/Licensed Shared Access (LSA), or any combination of these technologies.

Aspects of the present disclosure are initially described in the context of a wireless communication system. Aspects of the disclosure are subsequently illustrated and described with reference to apparatus diagrams, system diagrams, and flowcharts relating to exchanging radar information using a side communication channel to improve multi-radar coexistence.

Fig. 1 illustrates an example wireless network 100 (e.g., an NR network, a 5G network, or any other type of wireless communication network or system) in accordance with aspects of the present disclosure.

As illustrated in fig. 1, the wireless network 100 may include several base stations 110 and other network entities. Base station 110 may be a station in communication with UE 120. Each base station 110 may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to a coverage area of a node B and/or a node B subsystem serving the coverage area, depending on the context in which the term is used. In an NR system, the terms "cell" and evolved node B (eNB), node B, 5G NB, AP, NR base station, 5G radio node B (gNB), or transmission/reception point (TRP) may be interchanged. In some aspects, a cell may not necessarily be stationary and the geographic area of the cell may move according to the location of the mobile base station 120. In some aspects, base stations 110 may be interconnected with each other and/or to one or more other base stations 110 or network nodes (not shown) in wireless network 100 through various types of backhaul interfaces, such as direct physical connections, virtual networks, or the like using any suitable transmission network.

In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular Radio Access Technology (RAT) and may operate on one or more frequencies. RATs may also be referred to as radio technologies, air interfaces, etc. The frequency may also be referred to as a carrier wave, frequency channel, etc. Each frequency may support a single RAT in a given geographical area in order to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks may be deployed.

Base station 110 may provide communication coverage for macro cells, pico cells, femto cells, and/or other types of cells. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs 120 with service subscription. A picocell may cover a relatively small geographic area and may allow unrestricted access by UEs 120 with service subscription. A femtocell may cover a relatively small geographic area (e.g., a residence) and may allow restricted access by UEs 120 associated with the femtocell (e.g., UEs in a Closed Subscriber Group (CSG), UEs of users in a residence, etc.). The base station 110 for a macro cell may be referred to as a macro base station 110. A base station for a pico cell may be referred to as a pico base station. The base station for a femto cell may be referred to as a femto base station or a home base station. In the example shown in fig. 1, the base stations 110a, 110b, and 110c may be macro base stations for macro cells 102a, 102b, and 102c, respectively. Base station 110x may be a pico base station for pico cell 102 x. Base stations 110y and 110z may be femto base stations for femto cells 102y and 102z, respectively. A base station may support one or more (e.g., three) cells.

The wireless network 100 may also include relay stations. A relay station is a station that receives a transmission of data and/or other information from an upstream station (e.g., base station 110 or UE 120) and sends the transmission of data and/or other information to a downstream station (e.g., UE 120 or base station 110). The relay station may also be a UE 120 that relays transmissions for other UEs 120. In the example shown in fig. 1, relay 110r may communicate with base station 110a and UE 120r to facilitate communications between base station 110a and UE 120 r. A relay station may also be referred to as a relay base station, relay, etc.

The wireless network 100 may be a heterogeneous network including different types of base stations 110 (e.g., macro base stations, pico base stations, femto base stations, relays, etc.). These different types of base stations may have different transmit power levels, different coverage areas, and may have different impact on interference in the wireless network 100. For example, a macro base station may have a high transmit power level (e.g., 20 watts), while a pico base station, or femto base station, or relay may have a lower transmit power level (e.g., one (1) watt).

The wireless network 100 may support synchronous or asynchronous operation. For synchronous operation, the base stations 110 may have similar frame timing, and transmissions from different base stations 110 may be approximately aligned in time. For asynchronous operation, the base stations 110 may have different frame timings, and transmissions from different base stations 110 may not be aligned in time. The techniques described herein may be used for both synchronous and asynchronous operation.

The network controller 130 may be coupled to a set of base stations 110 and may provide coordination and control of these base stations 110. The network controller 130 may communicate with the base station 110 via a backhaul. The base stations 110 may also communicate with each other directly or indirectly, e.g., via wireless or wired backhaul.

UEs 120 (e.g., 120x, 120y, etc.) may be dispersed throughout wireless network 100, and each UE may be stationary or mobile. UE 120 may also be referred to as a mobile station, terminal, access terminal, subscriber unit, station, customer Premise Equipment (CPE), cellular telephone, smart phone, personal Digital Assistant (PDA), wireless modem, wireless communication device, handheld device, laptop, cordless telephone, wireless Local Loop (WLL) station, tablet device, camera, gaming device, netbook, smartbook, superbook, medical device or equipment, healthcare device, biometric sensor/device, wearable device (such as a smart watch, smart garment, smart glasses, virtual reality glasses, smart wristband, smart jewelry (e.g., smart ring, smart necklace, etc.), entertainment device (e.g., music device, video device, satellite radio, etc.), vehicle component or sensor, smart meter/sensor, robot, drone, industrial manufacturing equipment, positioning device (e.g., global Positioning System (GPS), beidou, terrestrial, etc.), or any other suitable device configured to communicate via a wireless or wired medium. Some UEs 120 may be considered Machine Type Communication (MTC) devices or evolved MTC (eMTC) devices, which may include remote devices that may communicate with base station 110, another remote device, or some other entity. MTC may refer to communications involving at least one remote device at least one end of the communications and may include forms of data communications involving one or more entities that do not necessarily require human-machine interaction. The MTC UEs may include UEs 120 capable of MTC communications with MTC servers and/or other MTC devices through, for example, a Public Land Mobile Network (PLMN). MTC and evolved MTC (eMTC) UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, cameras, location tags, etc., which may communicate with a base station 110, another device (e.g., a remote device), or some other entity. The wireless node may provide connectivity to or to a network (e.g., a wide area network such as the internet or a cellular network), for example, via a wired or wireless communication link. MTC UEs, as well as other UEs 120, may be implemented as internet of things (IoT) devices, e.g., narrowband IoT (NB-IoT) devices. In NB IoT, UL and DL have higher periodicity and repetition interval values when UE 120 decodes data within the extended coverage.

In fig. 1, the solid line with double arrows indicates the desired transmission between UE 120 and the serving base station, which is base station 110 designated to serve UE 120 on DL and/or UL. The dashed lines with double arrows indicate interfering transmissions between UE 120 and base station 110.

Some wireless networks (e.g., LTE) utilize OFDM on the DL and single carrier frequency division multiplexing (SC-FDM) on the UL. OFDM and SC-FDM divide the system bandwidth into a plurality of (K) orthogonal subcarriers, which are also commonly referred to as tones, bins, etc. Each subcarrier may be modulated with data. In general, the modulation symbols are transmitted in the frequency domain for OFDM and in the time domain for SC-FDM. The spacing between adjacent subcarriers may be fixed and the total number of subcarriers K may depend on the system bandwidth. For example, the subcarrier spacing may be 15kHz and the minimum resource allocation (referred to as a "resource block") may be twelve (12) subcarriers (or one hundred eighty (180) kHz). Thus, for a system bandwidth of 1.25, 2.5, 5, 10, or 20MHz, the nominal FFT size may be equal to one hundred twenty-eight (128), two hundred fifty-six (256), five hundred twelve (512), one thousand twenty-four (1024), or two thousand forty-eight (2048), respectively. The system bandwidth may also be divided into sub-bands. For example, a subband may cover 1.08MHz (e.g., six (6) resource blocks), and there may be 1, two (2), four (4), eight (8), or sixteen (16) subbands for a system bandwidth of 1.25, 2.5, 5, 10, or 20 MHz.

While aspects of the examples described herein may be associated with LTE technology, aspects of the disclosure may be applicable to other wireless communication systems (such as NR or other wireless communication systems). NR may utilize OFDM with CP on UL and DL and may include support for half-duplex operation using Time Division Duplex (TDD). A single component carrier bandwidth of one hundred (100) MHz may be supported. The NR resource block can span 12 subcarriers with a subcarrier bandwidth of seventy-five (75) kHz over a 0.1 millisecond (ms) duration. Each radio frame may include fifty (50) subframes having a length of 10 ms. Thus, each subframe may have a length of 0.2 ms. Each subframe may indicate a link direction (e.g., DL or UL) for data transmission and the link direction for each subframe may be dynamically switched. Each subframe may include DL/UL data and DL/UL control data. UL and DL subframes (e.g., for NR) may be described in more detail with reference to fig. 6A, 6B, 7A, and 7B. Beamforming may be supported and beam directions may be dynamically configured. MIMO transmission with precoding may also be supported. MIMO configuration in DL may support up to 8 transmit antennas (multi-layer DL transmission with up to 8 streams) and up to 2 streams per UE 120. Multi-layer transmissions of up to 2 streams per UE may be supported. Up to 8 serving cells may be used to support aggregation of multiple cells. Alternatively, the NR may support a different air interface than the OFDM-based interface. An NR network may comprise entities such as Central Units (CUs) and/or Distributed Units (DUs).

In some aspects, access to an air interface may be scheduled, where a scheduling entity (e.g., base station 110) allocates resources for communication among some or all devices and equipment within its service area or cell. Within this disclosure, a scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities, as discussed further herein. That is, for scheduled communications, the subordinate entity utilizes the resources allocated by the scheduling entity. Base station 110 is not the only entity that can be used as a scheduling entity. That is, in some aspects, UE 120 may act as a scheduling entity to schedule resources for one or more subordinate entities (e.g., one or more other UEs 120). In this aspect, a first UE 120 acts as a scheduling entity and other UEs 120 utilize resources scheduled by the first UE 120 for wireless communication. UE 120 may be used as a scheduling entity in a peer-to-peer (P2P) network and/or in a mesh network. In a mesh network example, UEs 120 may optionally communicate directly with each other in addition to communicating with the scheduling entity.

Thus, in a wireless communication network having scheduled access to time-frequency resources and having cellular, P2P, and mesh configurations, a scheduling entity and one or more subordinate entities may utilize the scheduled resources to communicate.

As discussed herein, a Radio Access Network (RAN) may include a CU and one or more DUs. An NR base station (e.g., an eNB, a 5G B node, a node B, a TRP, an AP, or a gNB) can correspond to one or more base stations 110. The NR cell may be configured as an access cell (ACell) or a data only cell (DCell). For example, the RAN (e.g., CU or DU) may configure the cells. The DCell may be a cell used for carrier aggregation or dual connectivity but not for initial access, cell selection/reselection, or handover. In some cases, the DCell may not transmit a Synchronization Signal (SS), and in other cases, the DCell may transmit the SS. The NR base station may transmit a DL signal indicating a cell type to UE 120. Based on the cell type indication, UE 120 may communicate with the NR base station. For example, UE 120 may determine NR base stations to consider for cell selection, access, handover, and/or measurement based on the indicated cell type.

In some cases, UE 120 may be an example of a vehicle operating within wireless network 100. In these cases, UE 120 may detect other UEs 120 and communicate directly with other UEs 120 (e.g., without communication with base station 110 or with minimal communication with base station 110). In some cases, UE 120 may transmit a radar waveform to detect nearby UE 120. However, if these other UEs 120 also communicate radar waveforms to detect target devices, multiple radar sources may result in interference and poor detection performance. To alleviate such problems, each UE 120 may transmit an indication of the waveform parameters used by that UE 120 so that nearby UEs 120 may identify other radar waveforms and reduce interference caused by those radar waveforms.

Fig. 2 illustrates an example logical architecture of a distributed RAN 200 in accordance with aspects of the present disclosure. The distributed RAN 200 may be implemented in a wireless communication system illustrated in fig. 1. The 5G access node 206 may include an Access Node Controller (ANC) 202. The ANC may be a CU of the distributed RAN 200. The backhaul interface to the next generation core network (NG-CN) 204 may terminate at the ANC 202. The backhaul interface to the neighboring next generation access node (NG-AN) 210 may terminate at the ANC 202.ANC 202 may include one or more TRP 208 (which may also be referred to as a base station, NR base station, node B, 5G NB, AP, eNB, gNB, or some other terminology). As described herein, TRP 208 may be used interchangeably with "cell".

TRP 208 may be an example of a DU. TRP 208 may be connected to one ANC (e.g., ANC 202) or more than one ANC. For example, for RAN sharing, radio as a service (RaaS), and service-specific ANC deployments, TRP 208 may be connected to more than one ANC 202.TRP 208 may include one or more antenna ports. TRP 208 may be configured to service traffic to UEs individually (e.g., in dynamic selection) or jointly (e.g., in joint transmission).

The local architecture may be used to illustrate the outbound (fronthaul) definitions. The architecture may be defined such that the architecture may support outbound solutions across different deployment types. For example, the architecture may be based on transport network capabilities (e.g., bandwidth, latency, and/or jitter).

The architecture may share features and/or components with LTE. According to aspects, the NG-AN 210 may support dual connectivity with the NR. The NG-AN 210 may share a common forward path for LTE and NR.

The architecture may enable collaboration between and among the TRPs 208. For example, the collaboration may be preset within the TRPs 208 and/or across each TRP 208 via the ANC 202. According to aspects, an inter-TRP interface may not be required/present.

According to aspects, dynamic configuration of split logic functions may exist within an architecture. A Radio Resource Control (RRC) layer, a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, a Medium Access Control (MAC) layer, and a Physical (PHY) layer may be adaptively placed at a DU or CU (e.g., at TRP 208 or ANC 202, respectively). According to certain aspects, a base station may include a CU (e.g., ANC 202) and/or one or more distributed units (e.g., one or more TRPs 208). In some cases, the distributed RAN 200 may support systems that include multi-radar coexistence. In these cases, the distributed RAN 200 may support the use of side communication channels to exchange radar information. Exchanging radar information may allow devices to select radar waveforms based on radar information of other devices, allowing improved multi-radar coexistence between devices.

Fig. 3 illustrates an example physical architecture of a distributed RAN 300 in accordance with aspects of the present disclosure. A centralized core network unit (C-CU) 302 may host core network functions. C-CU 302 can be deployed centrally. The C-CU 302 functionality may be offloaded (e.g., to Advanced Wireless Services (AWS)) in an effort to handle peak capacity.

A centralized RAN unit (C-RU) 304 may host one or more ANC functions. Optionally, the C-RU 304 may host the core network functions locally. The C-RU 304 may have a distributed deployment. The C-RU 304 may be closer to the network edge.

DU 306 may host one or more TRPs (e.g., edge Node (EN), edge Unit (EU), radio Head (RH), smart Radio Head (SRH), etc.). DU 306 may be located at the edge of a network with RF functionality. In some cases, the distributed RAN 300 may support devices that use side communication channels to exchange radar information to improve multi-radar coexistence. In some cases, distributed RAN 300 may allow for centralized operation, where DU 306 may transmit radar information to the vehicles covered by the DU 306.

Fig. 4 illustrates example components of a base station 110 and a UE 120 (e.g., as illustrated in fig. 1) in a wireless communication system 400 in accordance with aspects of the disclosure. As described herein, the base station 110 may include one or more TRPs. One or more components of base station 110 and UE 120 may be used to practice aspects of the present disclosure. For example, antennas 452, processors 466, 458, 464 and/or controller/processor 480 of UE 120, and/or antennas 434, processors 430, 420, 438 and/or controller/processor 440 of base station 110 may be used to perform the operations described herein.

Fig. 4 shows a block diagram of a design of a base station 110 and a UE 120, which may be one of the base stations and one of the UEs described with reference to fig. 1. For the constrained association scenario, base station 110 may be macro base station 110c in fig. 1, and UE 120 may be UE 120y. Base station 110 may also be some other type of base station. Base station 110 may be equipped with antennas 434a through 434t and UE 120 may be equipped with antennas 452a through 452r.

At base station 110, transmit processor 420 may receive data from data source 412 and control information from controller/processor 440. The control information may be used for a Physical Broadcast Channel (PBCH), a Physical Control Format Indicator Channel (PCFICH), a physical hybrid automatic repeat request (ARQ) indicator channel (PHICH), a Physical Downlink Control Channel (PDCCH), and so on. The data may be for a Physical Downlink Shared Channel (PDSCH) or the like. Transmit processor 420 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The processor 420 may also generate reference symbols (e.g., for a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), a cell-specific reference signal (CRS), etc.). A Transmit (TX) MIMO processor 430 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to Modulators (MODs) 432a through 432t. For example, TX MIMO processor 430 may perform certain aspects described herein with respect to Reference Signal (RS) multiplexing. Each modulator 432 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator 432 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a DL signal. DL signals from modulators 432a through 432t may be transmitted via antennas 434a through 434t, respectively.

At UE 120, antennas 452a through 452r may receive DL signals from base station 110 and may provide received signals to demodulators (DEMODs) 454a through 454r, respectively. Each demodulator 454 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator 454 may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. MIMO detector 456 may obtain received symbols from all demodulators 454a through 454r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. For example, MIMO detector 456 may provide detected RSs transmitted using techniques described herein. A receive processor 458 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for UE 120 to a data sink 460, and provide decoded control information to a controller/processor 480. In accordance with one or more scenarios, coordinated multipoint (CoMP) aspects may include providing antennas, as well as some Tx/receive (Rx) functionality, such that they reside in DUs. For example, some Tx/Rx processing may be done in a CU, while other processing may be done at a DU. According to one or more aspects as shown in the figures, the base station MOD/DEMOD 432 may be in a DU.

On the UL, at UE 120, a transmit processor 464 may receive and process data (e.g., for a Physical Uplink Shared Channel (PUSCH)) from data source 462 and control information (e.g., for a Physical Uplink Control Channel (PUCCH)) from a controller/processor 480. The transmit processor 464 may also generate reference symbols for a reference signal. The symbols from transmit processor 464 may be precoded by a TX MIMO processor 466 if applicable, further processed by the demodulators 454a through 454r (e.g., for SC-FDM, etc.), and transmitted to the base station 110. At base station 110, UL signals from UE 120 may be received by antennas 434, processed by modulators 432, detected by MIMO detector 436 if applicable, and further processed by a receive processor 438 to obtain decoded data and control information sent by UE 120. The receive processor 438 may provide decoded data to a data sink 439 and decoded control information to the controller/processor 440.

Controllers/processors 440 and 480 may direct the operation at base station 110 and UE 120, respectively. The processor 440 and/or other processors and modules at the base station 110 may perform or direct processes for the techniques described herein. Processor 480 and/or other processors and modules at UE 120 may also perform or direct processes for the techniques described herein. Memories 442 and 482 may store data and program codes for base station 110 and UE 120, respectively. The scheduler 444 may schedule UEs for data transmission on DL and/or UL.

Although fig. 4 illustrates communication between base station 110 and UE 120, in some systems, UEs 120 may detect each other and communicate information directly with each other (e.g., on a side communication channel). In these cases, UE 120 may detect other UEs 120 and communicate directly with other UEs 120 (e.g., without communication through base station 110 or relayed by base station 110). In some cases, UE 120 may transmit a radar waveform (e.g., using antenna 452) to detect nearby UE 120. To improve multi-radar coexistence between UEs 120, each UE 120 may transmit an indication of waveform parameters used by that UE 120 so that nearby UEs 120 may identify other radar waveforms and reduce interference caused by those waves. For example, UE 120 may change its waveform and/or waveform parameters for at least a subset of the chirps based on parameters selected by nearby UE 120 to achieve interference shaping, suppression, or both. This may improve the reliability of the target detection procedure performed by UE 120.

Fig. 5A illustrates an example of a DL centric sub-frame 500A according to aspects of the present disclosure. DL centric sub-frame 500A may comprise a control portion 502A. The control portion 502A may be present in an initial or beginning portion of the DL centric sub-frame 500A. The control portion 502A may include various scheduling information and/or control information corresponding to various portions of the DL centric sub-frame 500A. In some configurations, the control portion 502A may be a PDCCH, as illustrated in fig. 5A.

DL centric sub-frame 500A may also include DL data portion 504A. DL data portion 504A may sometimes be referred to as the payload of DL centric sub-frame 500A. DL data portion 504A may include communication resources for communicating DL data from scheduling entity 202 (e.g., eNB, base station, node B, 5G NB, TRP, gNB, etc.) to a subordinate entity (e.g., UE 120). In some configurations, DL data portion 504A may be a PDSCH.

DL centric sub-frame 500A may also include a common UL portion 506A. The common UL portion 506A may sometimes be referred to as a UL burst, a common UL burst, and/or various other suitable terms. The common UL portion 506A may include feedback information corresponding to various other portions of the DL centric sub-frame 500A. For example, the common UL portion 506 may include feedback information corresponding to the control portion 502A. Non-limiting examples of feedback information may include an Acknowledgement (ACK) signal, a Negative Acknowledgement (NACK) signal, a hybrid automatic repeat request (HARQ) indicator, and/or various other types of information. The common UL portion 506A may include additional or alternative information, such as information related to a Random Access Channel (RACH) procedure, a Scheduling Request (SR), a Sounding Reference Signal (SRs), and various other suitable types of information.

As illustrated in fig. 5A, the end of DL data portion 504A may be separated in time from the beginning of common UL portion 506A. This time separation may sometimes be referred to as a gap, a Guard Period (GP), a guard interval, and/or various other suitable terms. This separation provides time for a handoff from DL communication (e.g., a receive operation by a subordinate entity (e.g., UE 120)) to UL communication (e.g., a transmission by a subordinate entity (e.g., UE 120)). However, those of ordinary skill in the art will appreciate that the foregoing is merely one example of a DL centric sub-frame 500A and that alternative structures with similar features may exist without necessarily deviating from the aspects described herein.

Fig. 5B illustrates an example of an Uplink (UL) centric subframe 500B according to aspects of the present disclosure. UL center subframe 500B may include a control portion 502B. The control portion 502B may be present in an initial or beginning portion of UL-centric sub-frame 500B. The control portion 502B in fig. 5B may be similar to the control portion 502A described herein with reference to fig. 5A. UL center subframe 500B may also include UL data portion 504B. UL data portion 504B may sometimes be referred to as the payload of UL-centric sub-frame 500B. The UL portion may refer to communication resources used to communicate UL data from a subordinate entity (e.g., UE 120) to a scheduling entity 202 (e.g., base station 110). In some configurations, the control portion 502B may be PUSCH. As illustrated in fig. 5B, the end of control portion 502B may be separated in time from the beginning of UL data portion 504B. This time separation may sometimes be referred to as a gap, GP, guard interval, and/or various other suitable terms. This separation provides time for a handoff from DL communication (e.g., a receive operation by scheduling entity 202) to UL communication (e.g., a transmission by scheduling entity 202).

UL center subframe 500B may also include a common UL portion 506B. The common UL portion 506B in fig. 5B may be similar to the common UL portion 506A described herein with reference to fig. 5A. The common UL portion 506B may additionally or alternatively include information related to Channel Quality Indicators (CQIs), SRS, and various other types of information. Those of ordinary skill in the art will appreciate that the foregoing is merely one aspect of UL-centric subframe 500B and that alternative structures with similar features may exist without necessarily departing from the aspects described herein.

As described herein, UL centric sub-frame 500B may be used to transmit UL data from one or more mobile stations to a base station while DL centric sub-frames may be used to transmit DL data from the base station to the one or more mobile stations. In one aspect, a frame may include both UL-centric sub-frame 500B and DL-centric sub-frame 500A. In this aspect, the ratio of UL-centric sub-frame 500B to DL-centric sub-frame 500A in a frame may be dynamically adjusted based on the amount of UL data and the amount of DL data to be transmitted. For example, if there is more UL data, the ratio of UL-centric sub-frame 500B to DL-centric sub-frame 500A may be increased. Conversely, if there is more DL data, the ratio of UL-centric sub-frame 500A to DL-centric sub-frame 500B may be reduced.

In some wireless communication systems, multiple radar sources may cause significant interference. Conventional radar waveforms, such as Frequency Modulated Continuous Wave (FMCW) radar, do not natively support multiple access and, therefore, may not be distinguishable from individual sources (e.g., automobiles). Thus in the case of multiple radar sources, it may be difficult to determine whether a reflection is from a detected target or interference from another radar source. For example, FMCW automotive radar may obtain range and velocity information from beat frequency (beat frequency), which consists of propagation delay and doppler frequency. Doppler shiftIntroduced by an object moving at a speed v and radar wavelength lambda. In a multi-radar coexistence scenario, transmissions from other radar sources (e.g., automobiles) may appear as false (ghost) targets, which may be particularly offensive because it may appear in the same angular direction as the desired reflected signal from the object (e.g., automobile) and may not be easily identified as a false or normal (desired) target. Furthermore, the direct signal from the radar source may be significantly stronger than the reflected signal from the target, and detecting a weak reflected signal in the presence of strong interfering transmissions from other radar sources may be problematic for the receiver. As such, UE 120 transmitting the radar waveform may not be able to identify one or more nearby targets (e.g., based on interference from direct radar signals transmitted by the targets).

Fig. 6A illustrates an example wireless communication system 600A in accordance with aspects of the disclosure. The wireless communication system 600A may include a radar-emitting vehicle 620 that moves from left to right. The vehicle 620 may be an example of the UE 120 as described with reference to fig. 1 to 5. Vehicle 620 may encounter other UEs 120 (e.g., vehicles 625 and 630) moving from right to left. Both vehicles 625 and 630 moving from right to left reflect back to desired signals 610 and 615, respectively (e.g., based on radar emitted by automobile 620). The vehicle 630 that is closest to the vehicle 620 moving from left to right, which is moving from right to left, may also transmit radar 605 or another type of signal, which may act as an interference to the vehicle 620 moving from left to right. If vehicle 630 transmits a radar waveform, vehicle 620 may not be able to distinguish the interference caused by the radar waveform from reflected signals indicative of nearby targets (e.g., nearby UEs 120, vehicles, structures, sources of interference, etc.).

Fig. 6B illustrates an example graph 600B showing received power of direct and reflected signals over distance, in accordance with aspects of the present disclosure. Graph 600B may illustrate the problem of interference from a direct signal because the interference due to direct transmission 617 is much stronger than the reflected signal 622 from the target. Axis 607 may represent a range of received power values (in dBm) for the signal and axis 612 may represent a distance from a source (e.g., radar-emitting vehicle 620) to a target (e.g., vehicle 630). The interference may appear as a false target at half the distance (e.g., plus a time offset) from the actual target and with high power. With the reflected signal from the target, the desired (i.e., reflected) signal may have a relatively low signal-to-interference ratio (SIR) due to near field effects, the direct transmission 617 is received at a much stronger power than the reflected (desired) signal 622 from the target, or both. That is, the interference may have a relatively high power compared to the desired signal reflected from the target.

Graph 600B shows the received signal power from a reflected (desired) path based on one device (e.g., due to radar transmission by a first source device) and the direct (interfering) signal from a second source device, assuming the same transmit power at both radar sources. The reflected signal may attenuate about 1/R ⁴ times, where R is the distance from the vehicle 630 that is reflecting the radar, and the direct interfering signal may attenuate about 1/R ² times, where R is the distance from the vehicle 630 that is transmitting the direct interfering radar signal. Thus, based on the example illustrated in fig. 6A and 6B, the reflected signal 622 from the desired target 625 located far from 635 (e.g., one hundred fifty (150) meters (m) away from the source vehicle 620) may be weaker than the direct interference signal from the nearby source 630 located far from 640 (e.g., 10 m), and may present a challenging environment for target detection. It is noted that in some scenarios, some spatial rejection (spatial rejection) is possible to mitigate near field effects and depends on the geometric design (e.g., desired radar source, target, location of interfering radar source, etc.) and the spatial response of the radar receiver antenna. However, such spatial rejection may not always occur. For example, a situation where three cars in fig. 6A are in (or close to) a straight line to have no (or a small) angle difference between the two radio paths (the radio path of the desired radar to the target and the radio path of the desired radar to the interfering radar) may not always include a spatial rejection.

The methods, apparatus, and non-transitory processor-readable storage media of the present disclosure may enable multi-channel coexistence using side communication channels. In one aspect, an FMCW waveform is used. In some cases (including for automobiles), FMCW is the most commonly used waveform. However, the operation of the present disclosure is also applicable to other radar waveforms. In the case of FMCW, the frequency of the waveform varies linearly with time as a function of a saw tooth or triangle. The vehicle 620 transmitting the radar waveform may receive and process the reflected signals from the target(s) and detect range and doppler for each target based on the difference in the received transmitted frequencies.

In FMCW, the radar waveform may include a set of chirps, with each chirp having a particular chirp duration. The modulated signal may change the instantaneous frequency of the chirp linearly over a fixed period of time in the transmission (e.g., sweep time T _C). The transmitted signal (e.g., the transmitted radar waveform) may interact with the target and reflect back to the receiving antenna. The frequency difference Δf between the transmitted and received signals may increase with the delay of the received reflected signal. The range of the target from the radar is range, and the delay τ is linearly proportional to the range between the target and the source and is equal to the round trip travel time. The echo from the target may then be mixed with the transmitted signal and down-converted to produce a beat signal, which may be linearly proportional to the range between the target and the modulated signal source. Fig. 8 illustrates an FMCW system 800 with received and transmitted ramp waveforms modulated with sawtooth chirp in accordance with aspects of the present disclosure. Axis 805 may represent frequency and axis 810 may represent time. The time interval 815 may represent a delay τ. The frequency interval 820 may represent a frequency difference Δf between the transmitted signal (represented by 830) and the received signal (represented by 835). The frequency interval 825 may be a chirped frequency range B.

Parameters of the FMCW waveform may be changed for one or more chirps (e.g., each chirp) for interference randomization. Interference suppression and interference shaping is possible based on which parameters are changed across users by UE 120 (e.g., a vehicle) to select a mode. Fig. 7A and 7B illustrate frequency-time plots 700 of FMCW with different parameters according to aspects of the disclosure. In frequency-time plots 700A and 700B, B may represent the frequency range 705 or 707 of FMCW, and T _C may represent the duration of the chirp (shown at times 710 and 712). The frequency of the wave sweeps across the entire bandwidth portion from zero (0) to B (where 0 and B illustrate the frequency range and the actual frequency value may be any value in the bandwidth). Typically, the frequency of the radar may be swept from 1GHz to 2GHz. The chirp period may typically span between 10 and two hundred (200) microseconds.

Fig. 7A may illustrate the invariant waveform parameters of the FMCW waveform. In the example of fig. 7A and frequency-time plot 700A, 705 may represent B,710 may represent a time including N _C chirps, and each 715 may represent a chirp duration T _C. Fig. 7B may illustrate a change in slope β and/or frequency offset f ₀ parameters (e.g., where the change may be performed based on radar information of nearby vehicles to support interference shaping, suppression, or both). In the example of fig. 7B and graph 700B, 707 may represent B,712 may represent a time including N _C chirps, and each 717 may represent a chirp duration T _C (or may represent a reference chirp duration T _C). In some cases, multiple chirps may be transmitted in close proximity. At the receiver, multiple chirps may be processed (e.g., in sequence). In some cases (e.g., as illustrated), the chirp duration T _C may remain the same for the radar waveform, and the frequency of the wave may be swept through the frequency range B any number of times within the reference chirp duration. In other cases, the chirp duration T _C may correspond to a single frequency sweep through the frequency range B, and accordingly, the chirp duration T _C may vary for a set of chirps depending on the slope β. For "fast" chirps, the duration T _C is short, and for "slow" chirps, the T _C duration is long. In some cases, UE 120 (e.g., a vehicle) may select waveform parameters for transmitting a radar waveform, where the waveform parameters are applied to frequency-time plot 700A. The UE may change these selected waveform parameters for at least one chirp to yield selected waveform parameters corresponding to frequency-time plot 700B.

The system may be configured to determine a degree to which to change the chirp parameter. Two parameters defining a waveform for use over a chirp duration T _C may be a slope β and a frequency offset f ₀, where the slope is defined as β=b/T _C for a particular chirp. For example, an FMCW radar system may be designed to sweep frequencies linearly over 1GHz and 50us, resulting in a slope β=1 GHz/50us, and the frequency offset f ₀ may be set to any value between 0 and 1 GHz. The frequency offset f ₀ may correspond to an initial frequency value at the beginning of the chirp duration T _C. In fig. 7A, the slope and frequency offset may remain constant over multiple chirps. That is, B705 may be the same for each chirp in a set of chirps, and T _C 715a, 715B, and 715c may be the same for the set of chirps, resulting in a constant slope β for the set of chirps. Additionally, the frequency offset f ₀ may be the same for each chirp in the set of chirps. In fig. 7B, the UE (e.g., a vehicle in a vehicle networking (V2X) system) does not keep the parameters constant, but may change the parameters that determine the chirp frequency. Furthermore, if the mode is selected to change the slope and frequency offset for at least one chirp (e.g., each chirp), interference from other radar transmissions may be suppressed or shaped (e.g., offset) based on the changed waveform parameters. Based on the way the parameters are changed between different radar sources, two effects can occur. In the first aspect, interference between radar sources may be suppressed. Additionally or alternatively, in a second aspect, the interference may be shaped. Shaping the interference may involve delaying and/or frequency shifting the interference beyond what can be detected by the receiver. By specifically selecting the waveform parameters, the waveforms of the coexistence radars can be normalized so that they do not interfere with each other in a manner that affects the target detection performance.

In one aspect, certain choices of FMCW waveform parameters may make the radar waveform resemble a Zadoff-Chu sequence, which exhibits correlation properties (e.g., auto-correlation, cross-correlation, etc.) that may aid in interference suppression.

As previously discussed, two parameters that may vary from chirp to chirp are the slope β and the frequency offset f ₀. In the equations described herein, the slope and frequency of the chirp may be determined using two parameters (u, q) for a given chirp.

In the equations described herein, the slope of the chirp m may be determined asAnd the frequency offset may be determined as/>Where m=1, 2, 3..is the chirp index, T _C is the period of the chirp, B is the frequency range, and (u ^(m),q^(m)) is two parameters of the mth chirp that determine the FMCW waveform so that the waveform is similar to a Zadoff-Chu sequence. Using this result, the parameter (u ^(m),q^(m)) may be selected at UE 120 such that interference between coexisting radars will be suppressed by utilizing the correlation properties of the Zadoff-Chu waveform. The equation describing these two parameters for a set of chirps may be:

Where T _C is the period of the chirp, B is the frequency range, β ^(m) is the slope and f ₀ ^(m) is the frequency offset, and (u ^(m),q^(m)) is the mth chirp, two parameters that determine the FMCW waveform. The Zadoff-Chu sequence is an example of a complex valued mathematical sequence. When the sequence is applied to a radio signal, an electromagnetic signal of constant amplitude is generated, whereby cyclically shifted versions of the sequence applied to the signal result in zero correlation with each other at the receiver. The "root sequence" is the generated Zadoff-Chu sequence that has not been shifted yet. These sequences exhibit the property that their cyclically shifted versions are orthogonal to each other, provided that each cyclic shift is greater than the combined multipath delay spread and propagation delay of the signal between the transmitter and receiver when viewed in the time domain of the signal.

In some cases, u _i ^(m)≠u_j ^(m), where (.) ^(m) is the mth chirp, and i and j are two radar transmitters (e.g., for two UEs 120 in close proximity to each other). In this case, the Zadoff Chu sequences of these radar transmitters may have cross-correlations, effectively raising the noise floor of the interference. Here, two users (e.g., corresponding to radar transmitters i and j) use different slopes u _i ^(m) and u _j ^(m) on the mth chirp. This may result in cross-correlation of the corresponding sequences for i and j, which may be limited by the length of the Zadoff Chu sequence. This cross-correlation may result in interference suppression among the two Zadoff Chu sequences. Correlation among the two Zadoff Chu sequences may raise the noise floor (e.g., thereby indicating that the two sequences are not orthogonal). In these cases, the cross-correlation may be relatively small (but non-zero), indicating that the interference may spread at low energies, which may appear as noise. The interference may be suppressed by the length of the Zadoff-Chu sequence. Accordingly, the interference may not appear as a false target, but rather as suppressed noise (e.g., suppressed by the interference), which raises the noise floor.

The UE (e.g., vehicle) may shape the interference by setting the frequency offset such that spurious targets or interference peaks appear outside the range of interest. For example, if u _i ^(m)＝u_j ^(m) (e.g., the slope of transmitter i of the mth chirp is equal to the slope of transmitter j of the mth chirp), the peak interference may be shifted relative to (q _i ^(m)-q_j ^(m)) (e.g., the frequency offset parameter of transmitter i of the mth chirp minus the frequency offset parameter of transmitter j of the mth chirp). In one aspect, the peak interference may be shifted to be greater than the range of interest. For example, for a range target of 150m (e.g., a range of interest), a bandwidth of 1GHz, a chirp duration T _C of 10 microseconds, a slope parameter u _i ^(m)＝u_j ^(m) = 1, and a receiver with a sampling rate of 1 gigasample per second (Gsps), (q _i ^(m)-q_j ^(m)) may be set between [1000,9000] such that mutual interference will occur at distances greater than 150m, which may be outside of the range expected from any target of reflected signals according to the design. Thus, if the slope u ^(m) of radar transmitters i and j is the same slope magnitude, then the frequency offsets q _i ^(m) and q _j ^(m) may be selected such that the peaks of the interference may be shifted beyond a predefined or dynamically determined range of interest. In one aspect, even if radar transmitters are adjacent to each other (e.g., within close proximity), energy from each radar transmitter will appear to be far from the other transmitter and not appear to be interference within the interference range based on interference shaping techniques.

In a phase-coded FMCW system, avoiding coherent addition of chirps with the same parameters helps to suppress interference. For example, 90% of the chirps in a set of waveforms may be orthogonal, i.e., the parameters of each chirp are selected such that interference between chirps of different waveforms is suppressed or shaped. However, 10% of the chirp may still have the same parameters across the waveforms and thus may be coherently superimposed. Phase codes may be added to the waveform to suppress or shape the interference such that each chirp in a set of chirps (e.g., each chirp in the waveform) has an associated phase, where the phase may change from chirp to chirp. The following Zadoff-Chu sequence illustrates an example in which a phase sequence is applied:

In this case, m is a chirp index, where m=0, 1, … N, N is the number of chirps (e.g., length of Zadoff Chu sequence), and N is a sample index within the mth chirp. The applied phase modulation may be determined based on the Zadoff Chu sequence and by selection of parameters (u, q). By adding phase codes, there are actually two nested Zadoff-Chu sequences. First, for the original FMCW waveform selected by UE 120, each chirp is similar to a Zadoff-Chu sequence with a particular selection of parameters. Second, UE 120 implements a Zadoff-Chu sequence that represents phase modulation of the waveform.

The processing at the receiver side may also be varied to coherently combine the desired signals. For example, the receiver may coherently combine the desired signal at the receiver side using equalization, resampling, or some combination of these or other techniques.

For the equations described herein, the FMCW waveform may be changed for a set of chirps (e.g., each chirp) using the following set of parameters for interference randomization:

Where i is a transmitter index, m is a chirp index, N _C is a total number of chirps on which randomization is performed, The phase modulation applied across the N _C chirps is controlled, and (u _i ^(m),q_i ^(m)) the slope and frequency offset of the FMCW waveform in the mth chirp is determined. For example, UE 120 may select a codeword from a codebook, where the codeword indicates parameters to be used for a waveform. Multiple users may select FMCW parameters based on the codebook using the same codebook. In some cases, UE 120 may choose (e.g., randomly, pseudo-randomly based on a certain procedure, etc.) to have a uniform distribution/>, over a rangeUE 120 may additionally or alternatively select c _i：＝(u_i ^(m),q_i ^(m)),m＝1,…,N_c to maximize the "distance" among the codewords (e.g., codewords selected by nearby UE 120). If the slopes of the chirps are different, the "distance" measurement may be set to the maximum distance, and if the slopes are the same, the "distance" measurement may be set to be proportional to (q _i-q_k) (e.g., where the distance may reach a limit at the maximum distance if q _i-q_k > maximum delay).

These parameters may be selected from a codebook comprising a set of allowed parameter value patterns (e.g., codewords) when the car is in traffic. The codebook may be designed to produce low mutual interference among any two codewords. Thus, selecting waveform parameters based on the codebook may be done for multiple users to have low mutual interference in the system.

If the parameter pattern (e.g., codeword) being used by another vehicle having transmitter j is known to the vehicle having transmitter i, the vehicle having transmitter i may select a codeword that produces the least (or relatively less) mutual interference with the pattern being used by the vehicle having transmitter j. In one aspect, a vehicle having a transmitter i may determine a set of modes that are being used by other vehicles in the vicinity. The vehicle with transmitter i may select for its own transmission the codeword that causes the least mutual interference to the determined set of modes of other vehicles. In some cases, a side communication channel may be used to communicate the mode in which the vehicle is using, and nearby vehicles may listen (e.g., monitor) for such broadcast messages to determine the set of codewords being used in a certain proximity (e.g., within a certain distance range, within a detection range, etc.). Determining codewords used by nearby UEs 120 (e.g., vehicles) based on side communication channel transmissions may support low computational complexity.

To indicate a particular codeword selected from a codebook comprising a plurality of possible codewords, UE 120 may broadcast an indication of the selected codeword for receipt by nearby UE 120. For example, after selecting the mode of the waveform parameters, UE 120 may use a side communication channel to broadcast the mode being used for the radar waveform. For a parameter pattern (e.g., codeword) used on a set of chirps, the parameter pattern may be selected from a set of patterns (e.g., a codebook of patterns). In some cases, the parameters may be selected from a codebook containing all supported parameter patterns. In these cases, the selected pattern may be identified by an index specified in the codebook (e.g., rather than based on all parameters in the pattern). Transmitting the index indicating the codeword instead of the values of all parameters specified by the codeword can significantly reduce the payload size and overhead of the side communication channel transmission.

Side channels (e.g., V2X communication channels or cellular communications) may be used to communicate the location of the vehicle and the parameter pattern (or codeword) being used. Centralized (e.g., base station based) and/or decentralized (e.g., vehicle-to-vehicle based) methods may be used to gather information about codewords (e.g., parameter patterns used on chirps) that are being used in the vicinity of the car. In centralized operation, UE 120 may receive information from base station 110 regarding codewords in use in the vicinity of UE 120 (e.g., with a range threshold). In decentralized operation, UE 120 may receive information (e.g., on a side communication channel) from other UEs 120 in the vicinity of the UE 120 regarding codewords in use in the vicinity of the UE 120. For example, each UE 120 may broadcast an indication of its own selected waveform parameters for receipt by other UEs monitoring side channel transmissions. Interference cancellation and selection of the vehicle's own codeword may be accomplished based on the side information. UE 120 may select a mode that is most orthogonal (e.g., causes least interference) to the modes used by other UEs 120 in its vicinity because all cars in the vicinity of UE 120 are broadcasting their mode. In the case of a centralized V2X (C-V2X) mode of operation, there may be two side link (or side communication) channels. One is a physical side link shared channel (PSSCH) that may be used to transmit and receive data, and the other is a physical side link control channel (PSCCH) that may be used to transmit and receive control signaling related to the associated PSSCH channel.

Radar target detection includes: a radar waveform is transmitted that includes N _C chirps, where each chirp has a duration T _C (which may be the same for all chirps in the waveform or may be different for one or more chirps in the waveform). In one aspect, each chirp uses an FMCW waveform. In another aspect, each chirp uses a phase-encoded FMCW waveform. In another aspect, the at least one chirp uses an FMCW waveform or a phase-coded FMCW waveform. To suppress interference, the waveform and/or waveform parameters may be changed for at least a subset of the N _C chirps. In one aspect, the parameter being changed is determined from a set of possible patterns (e.g., codewords), where a pattern is a codeword and a set of patterns is a codebook. In one aspect, a UE may broadcast its codeword on a side channel or a side communication channel.

UE 120 (e.g., a vehicle) may use side information (e.g., broadcast information) received from other vehicles indicating a parameter pattern (or codeword) that the other vehicle is using, a location of the other vehicle, a location of UE 120, or some combination of such information to determine a set of codewords that are being used in the vicinity of UE 120 (e.g., according to some proximity threshold or definition). In one scenario, information of a set of codewords in use in the vicinity of UE 120 is communicated to UE 120 (e.g., an automobile) by direct communication with a network entity (e.g., base station 110, or a Road Side Unit (RSU), or another UE 120).

In one scenario, UE 120 may broadcast a signal (e.g., a beacon, an encoded discovery message, etc.) on a side channel to announce its presence. The message may contain only a subset of the information (e.g., the message may or may not indicate the selected waveform parameters), but is used as an indication that the vehicle is present and actively transmitting the radar waveform. The nearby vehicles receiving the message may use this information to estimate waveform parameters that those nearby vehicles are using.

The RSUs may be radio base stations installed along a roadside or at an intersection. For example, the RSU may be on a traffic signal pole, a light pole, an electronic toll booth, or the like. The transmitted message may have a common or dynamically determined Transport Block (TB) size, which may represent the message size in a Physical Resource Block (PRB).

Fig. 9 is a flow chart illustrating a method for implementing coexistence of multiple radar sources by a UE, wherein the UE may suppress radar interference in a communication system, in accordance with aspects of the present disclosure. In step 910, the UE may select a mode (e.g., a mode of waveform parameters, a codeword, etc.) based on which parameters are changed across users. The UE may determine the parameters that change across nearby users based on receiving one or more transmissions (e.g., from a centralized base station or broadcast by nearby UEs) indicating the information. In step 920, the UE may select waveform parameters based on one or more codebooks. In step 930, the UE may change a waveform parameter in at least one of a set of chirps corresponding to the waveform. In step 940, the UE may select a frequency offset such that interference peaks of one or more nearby UEs occur outside of the range of interest. In step 945, the UE may add a phase code to the waveform. Step 950 involves the UE broadcasting the selected mode being used using the side communication channel (e.g., after performing one or more of the above operations). In some cases, after the selection process, the UE may transmit (e.g., transmit) the determined radar waveform for target detection.

Fig. 10 is a flow chart illustrating a method for implementing coexistence of multiple radar sources by a UE, the method comprising suppressing radar interference in a communication system, in accordance with aspects of the present disclosure. In step 1010, the UE may select waveform parameters based on the codebook (e.g., from a set of codewords received for UEs within a certain proximity of the UE). In step 1020, the UE may select a pattern of waveform parameters from a codebook of patterns. In step 1030, the UE may broadcast the selected mode of the waveform parameters being used using the side communication channel. In step 1040, the UE may receive information (e.g., through direct or relayed communications with a network entity) indicating the set of codewords being used in the vicinity of the UE. Step 1050 involves the UE broadcasting a signal such as a beacon or encoded discovery message using a side communication channel (e.g., to indicate the presence and/or location of the UE).

Fig. 11 illustrates certain components that may be included within a base station 1101. The base station 1101 may be an access point, a node B, an evolved node B, or the like. The base station 1101 includes a processor 1103. The processor 1103 may be a general purpose single-chip or multi-chip microprocessor (e.g., an advanced Reduced Instruction Set Computer (RISC) machine (ARM) microprocessor), a special purpose microprocessor (e.g., a Digital Signal Processor (DSP), a microcontroller, a programmable gate array, etc.) the processor 1103 may be referred to as a Central Processing Unit (CPU).

The base station 1101 also includes a memory 1105. Memory 1105 may be any electronic component capable of storing electronic information. Memory 1505 may be implemented as Random Access Memory (RAM), read Only Memory (ROM), magnetic disk storage media, optical storage media, flash memory devices in RAM, on-board memory included with the processor, erasable Programmable ROM (EPROM), electrically Erasable Programmable ROM (EEPROM), registers, and so forth, including combinations thereof.

Data 1107 and instructions 1109 may be stored in memory 1105. The instructions 1109 may be executable by the processor 1103 to implement the methods disclosed herein. Executing the instructions 1109 may involve using the data 1107 stored in the memory 1105. When the processor 1103 executes the instructions 1109, various portions of the instructions 1109a may be loaded onto the processor 1103, and various pieces of data 1107a may be loaded onto the processor 1103.

The base station 1101 may also include a transmitter 1111 and a receiver 1113 to allow transmission and reception of signals to and from the wireless device 1101. The transmitter 1111 and the receiver 1113 may be collectively referred to as a transceiver 1115. Multiple antennas 1117 (e.g., antennas 1117a and 1117 b) may be electrically coupled to transceiver 1115. The base station 1101 may also include a plurality of transmitters, a plurality of receivers, and/or a plurality of transceivers (not shown).

The various components of base station 1101 may be coupled together by one or more buses, which may include a power bus, a control signal bus, a status signal bus, a data bus, and the like. For clarity, the various buses are illustrated in FIG. 11 as bus system 1119. Although fig. 9 and 10 are discussed herein with reference to a UE, it should be understood that a base station (such as base station 1101) may perform the corresponding transmission monitored and received by the UE discussed in fig. 9 and 10 and receive information indicated by the UE discussed in fig. 9 and 10. These operations may be implemented in hardware or software executed by a processor (e.g., the processor 1103 described with reference to fig. 11).

Fig. 12 illustrates certain components that may be included within a wireless communication device 1201. The wireless communication device 1201 may be an access terminal, a mobile station, a UE, or the like. The wireless communication device 1201 includes a processor 1203. The processor 1203 may be a general purpose single or multi-chip microprocessor (e.g. ARM), a special purpose microprocessor (e.g. DSP), a microcontroller, a programmable gate array, or the like. The processor 1203 may be referred to as a CPU. Although only a single processor 1203 is shown in the wireless communication device 1201 of fig. 12, in alternative configurations, a combination of processors (e.g., ARM and DSP) may be used.

The wireless communication device 1201 also includes a memory 1205. The memory 1205 may be any electronic component capable of storing electronic information. The memory 1205 may be implemented as RAM, ROM, magnetic disk storage media, optical storage media, flash memory devices in RAM, on-board memory included with the processor, EPROM, EEPROM, registers, and so forth, including combinations thereof.

Data 1207 and instructions 1209 may be stored in the memory 1205. The instructions 1209 may be executable by the processor 1203 to implement the methods disclosed herein. Executing the instructions 1209 may involve using the data 1207 stored in the memory 1205. When the processor 1203 executes the instructions 1209, various portions of the instructions 1209a may be loaded onto the processor 1203, and various pieces of data 1207a may be loaded onto the processor 1203.

The wireless communication device 1201 may also include a transmitter 1211 and a receiver 1213 to support the transmission and reception of signals to and from the wireless communication device 1201. The transmitter 1211 and receiver 1213 may be collectively referred to as a transceiver 1215. Multiple antennas 1217 (e.g., antennas 1217a and 1217 b) may be electrically coupled to transceiver 1215. The wireless communication device 1201 may also include a plurality of transmitters, a plurality of receivers, and a plurality of transceivers (not shown).

The various components of the wireless communication device 1201 may be coupled together by one or more buses, which may include a power bus, a control signal bus, a status signal bus, a data bus, and the like. For clarity, the various buses are illustrated in fig. 12 as bus system 1219. The wireless communication device 1201 may perform one or more of the operations described herein with reference to fig. 9 and 10. It should be noted that these methods describe possible implementations, and that the operations and steps may be rearranged or otherwise modified so that other implementations are possible. In some aspects, aspects from two or more methods may be combined. For example, aspects of each method may include steps or aspects of other methods, or other steps or techniques described herein. Thus, aspects of the present disclosure may provide for reception based on transmission resources or operations and transmission based on reception resources or operations. The functions described in the flowcharts of fig. 9 and 10 herein may be implemented in hardware or software executed by a processor (e.g., the processor 1203 described with reference to fig. 12).

The description herein is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software for execution by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and the appended claims. For example, due to the nature of software, the functions described herein may be implemented using software executed by a processor, hardware, firmware, hardwired or any combination thereof. Features implementing functions may also be physically located in various locations, including being distributed such that portions of the functions are implemented at different Physical (PHY) locations. In addition, as used herein (including in the claims), an "or" used in an item enumeration (e.g., an item enumeration accompanied by a phrase such as "at least one of" or "one or more of" indicates an inclusive enumeration, such that, for example, enumeration of at least one of A, B or C means a or B or C or AB or AC or BC or ABC (i.e., a and B and C).

Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. Non-transitory storage media may be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, non-transitory computer-readable media can comprise RAM, ROM, EEPROM, compact Disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory media that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk (disc) and disc (disc), as used herein, includes CD, laser disc, optical disc, digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

The techniques described herein may be used for various wireless communication systems such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA and other systems. The terms "system" and "network" are often used interchangeably. A CDMA system may implement a radio technology such as CDMA2000, universal Terrestrial Radio Access (UTRA), and the like. CDMA2000 covers IS-2000, IS-95, and IS-856 standards. IS-2000 release 0 and a are commonly referred to as CDMA2000 1X, etc. IS-856 (TIA-856) IS commonly referred to as CDMA2000 1xEV-DO, high Rate Packet Data (HRPD), or the like. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. TDMA systems may implement radio technologies such as global system for mobile communications (GSM). OFDMA systems may implement radio technologies such as Ultra Mobile Broadband (UMB), evolved UTRA (E-UTRA), IEEE 802.11 (wireless fidelity (Wi-Fi)), IEEE 802.16 (WiMAX), IEEE 802.20, flash-OFDM, and the like. UTRA and evolved UTRA (E-UTRA) are parts of the Universal Mobile Telecommunications System (UMTS)). 3GPP LTE and LTE-advanced (LTE-A) are new UMTS releases that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-a and GSM are described in the literature from 3 GPP. CDMA2000 and UMB are described in the literature from an organization named "third generation partnership project 2" (3 GPP 2). The techniques described herein may be used for both the systems and radio technologies mentioned herein and for other systems and radio technologies. However, the description herein describes an LTE system for purposes of example, and LTE terminology is used in most of the description, but these techniques are also applicable to applications other than LTE applications.

In LTE/LTE-a networks (including the networks described herein), the term eNB may be used generically to describe base stations. One or more wireless communication systems described herein may include heterogeneous LTE/LTE-a networks, where different types of enbs provide coverage for various geographic regions. For example, each eNB or base station may provide communication coverage for a macro cell, a small cell, or other type of cell. Depending on the context, the term "cell" is a 3GPP term that can be used to describe a base station, a carrier or Component Carrier (CC) associated with a base station, or a coverage area (e.g., sector, etc.) of a carrier or base station.

A base station may include or be referred to by those skilled in the art as a base transceiver station, a radio base station, an AP, a radio transceiver, a node B, an evolved node B, a home evolved node B, or some other suitable terminology. The geographic coverage area of a base station may be partitioned into sectors that form a portion of the coverage area. One or more wireless communication systems described herein may include different types of base stations (e.g., macro or small cell base stations). The UEs described herein may be capable of communicating with various types of base stations and network equipment (including macro enbs, small cell enbs, relay base stations, etc.). There may be overlapping geographic coverage areas of different technologies. In some cases, different coverage areas may be associated with different communication technologies. In some cases, the coverage area of one communication technology may overlap with the coverage area associated with another technology. Different technologies may be associated with the same base station or different base stations.

One or more wireless communication systems described herein may support synchronous or asynchronous operation. For synchronous operation, each base station may have similar frame timing, and transmissions from different base stations may be approximately aligned in time. For asynchronous operation, each base station may have different frame timing, and transmissions from different base stations may not be aligned in time. The techniques described herein may be used for synchronous or asynchronous operation.

DL transmissions described herein may also be referred to as forward link transmissions, while UL transmissions may also be referred to as reverse link transmissions. Each communication link described herein (including, for example, wireless communication system 100 of fig. 1) may include one or more carriers, where each carrier may be a signal (e.g., a waveform signal of a different frequency) composed of a plurality of subcarriers. Each modulated signal may be transmitted on a different subcarrier and may carry control information (e.g., reference signals, control channels, etc.), overhead information, user data, and the like. The communication links described herein may communicate bi-directional communications using Frequency Division Duplexing (FDD) (e.g., using paired spectrum resources) or TDD operation (e.g., using unpaired spectrum resources). A frame structure for FDD (e.g., frame structure type 1) and a frame structure for TDD (e.g., frame structure type 2) may be defined.

Thus, aspects of the present disclosure may provide for transmission-based reception and reception-based transmission. It should be noted that these methods describe possible implementations, and that the operations and steps may be rearranged or otherwise modified so that other implementations are possible. In some aspects, aspects from two or more methods may be combined.

The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed with a general purpose processor, a DSP, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration). Thus, the functions described herein may be performed by one or more other processing units (or cores) on at least one Integrated Circuit (IC). In various aspects, different types of ICs (e.g., structured/platform ASICs, FPGAs, or other half of custom ICs) may be used that may be programmed in any manner known in the art. The functions of each element may also be implemented in whole or in part in instructions embodied in a memory that are formatted to be executed by one or more general or application-specific processors.

In the drawings, similar components or features may have the same reference numerals. Further, individual components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference number is used in the specification, the description may be applied to any one of the similar components having the same first reference number regardless of the second reference number.

Claims (48)

1. A method implemented by a User Equipment (UE) for suppressing interference to radar in a communication system, comprising:

Selecting a waveform parameter for transmitting a radar waveform, the waveform parameter being a slope, a frequency offset, a duration of a chirp of the radar waveform, or a combination thereof, wherein the radar waveform comprises a plurality of chirps, and the selecting comprises changing the waveform parameter for at least one of the plurality of chirps;

Transmitting an indication of one or more selected waveform parameters over the communication system; and

The radar waveform is transmitted according to the selected waveform parameters.

2. The method of claim 1, wherein selecting the waveform parameters comprises:

a codeword is selected from a codebook comprising a plurality of codewords, wherein the codeword is indicative of a selected waveform parameter.

3. The method of claim 2, wherein selecting the waveform parameters comprises:

identifying a set of codewords for additional UEs within a threshold distance; and

The waveform parameters are changed for the at least one chirp to have a uniform distribution over a range such that the distance between the selected codeword and the identified codeword set is maximized.

4. The method of claim 1, wherein transmitting the indication of the one or more selected waveform parameters comprises:

The indication of the one or more selected waveform parameters is broadcast on one or more side communication channels between the UE and one or more additional UEs.

5. The method of claim 1, wherein transmitting the indication of the one or more selected waveform parameters comprises:

the indication of the one or more selected waveform parameters is transmitted on an uplink channel between the UE and a network entity.

6. The method of claim 1, further comprising:

Information of a set of codewords being used in the vicinity of the UE is received from a network entity.

7. The method of claim 1, further comprising:

a beacon, an encoded discovery message, or a combination thereof is broadcast on one or more side communication channels between the UE and one or more additional UEs to indicate a location of the UE.

8. The method of claim 1, further comprising:

Information of a set of codewords used by an additional UE is received over one or more multi-sided communication channels between the UE and one or more additional UEs, wherein the waveform parameters are changed based at least in part on the information of the set of codewords used by the additional UE.

9. The method of claim 8, further comprising:

Receiving a set of beacons, encoded discovery messages, or a combination thereof for the additional UE on the one or more side communication channels between the UE and the one or more additional UEs to indicate a location of the additional UE; and

A set of proximity values for the additional UE relative to the UE is determined, wherein the waveform parameters are changed based at least in part on the set of proximity values for the additional UE.

10. The method of claim 1, wherein the selected waveform parameters comprise a frequency range, a chirp duration, a frequency offset, or a combination thereof.

11. The method of claim 1, further comprising:

identifying a range of interest of an interference source for the radar waveform; and

The frequency offset of the radar waveform is set such that interference peaks of at least one interference source occur outside the range of interest.

12. The method of claim 1, further comprising:

One or more chirps of the radar waveform are phase encoded to avoid coherent superposition of the chirps with other radar waveforms in the communication system.

13. An apparatus implemented by a User Equipment (UE) for suppressing interference to radar in a communication system, comprising:

means for selecting a waveform parameter for transmitting a radar waveform, the waveform parameter being a slope, a frequency offset, a duration of a chirp, or a combination thereof, of the radar waveform, wherein the radar waveform comprises a plurality of chirps, and the selecting comprises changing the waveform parameter for at least one of the plurality of chirps;

means for transmitting an indication of one or more selected waveform parameters over the communication system; and

Means for transmitting the radar waveform according to the selected waveform parameters.

14. The apparatus of claim 13, wherein the means for selecting the waveform parameters comprises:

means for selecting a codeword from a codebook comprising a plurality of codewords, wherein the codeword is indicative of a selected waveform parameter.

15. The apparatus of claim 14, wherein the means for selecting the waveform parameters comprises:

means for identifying a set of codewords for additional UEs within a threshold distance; and

Means for changing the waveform parameters for the at least one chirp to have a uniform distribution over a range such that the distance between a selected codeword and an identified set of codewords is maximized.

16. The apparatus of claim 13, wherein means for transmitting the indication of the one or more selected waveform parameters comprises:

Means for broadcasting the indication of the one or more selected waveform parameters on one or more side communication channels between the UE and one or more additional UEs.

17. The apparatus of claim 13, wherein means for transmitting the indication of the one or more selected waveform parameters comprises:

Means for transmitting the indication of the one or more selected waveform parameters on an uplink channel between the UE and a network entity.

18. The apparatus of claim 13, further comprising:

Means for receiving information of a set of codewords in use in the vicinity of the UE from a network entity.

19. The apparatus of claim 13, further comprising:

Means for broadcasting a beacon, an encoded discovery message, or a combination thereof, on one or more side communication channels between the UE and one or more additional UEs to indicate a location of the UE.

20. The apparatus of claim 13, further comprising:

Means for receiving information of a set of codewords used by an additional UE over one or more multi-sided communication channels between the UE and one or more additional UEs, wherein the waveform parameters are changed based at least in part on the information of the set of codewords used by the additional UE.

21. The apparatus of claim 20, further comprising:

Means for receiving a set of beacons, encoded discovery messages, or a combination thereof for the additional UE on the one or more side communication channels between the UE and the one or more additional UEs to indicate a location of the additional UE; and

Means for determining a set of proximity values for the additional UE relative to the UE, wherein the waveform parameters are changed based at least in part on the set of proximity values for the additional UE.

22. The device of claim 13, wherein the selected waveform parameters comprise a frequency range, a chirp duration, a frequency offset, or a combination thereof.

23. The apparatus of claim 13, further comprising:

means for identifying a range of interest of an interfering source for the radar waveform; and

Means for setting a frequency offset of the radar waveform such that an interference peak of at least one interference source occurs outside the range of interest.

24. The apparatus of claim 13, further comprising:

Means for phase encoding one or more chirps of the radar waveform to avoid coherent superposition of chirps with other radar waveforms in the communication system.

25. An apparatus implemented by a User Equipment (UE) for suppressing interference to radar in a communication system, comprising:

A processor;

A memory coupled to the processor; and

Instructions stored in the memory and executable by the processor to cause the apparatus to:

Selecting a waveform parameter for transmitting a radar waveform, the waveform parameter being a slope, a frequency offset, a duration of a chirp of the radar waveform, or a combination thereof, wherein the radar waveform comprises a plurality of chirps, and the selecting comprises changing the waveform parameter for at least one of the plurality of chirps;

Transmitting an indication of one or more selected waveform parameters over the communication system; and

The radar waveform is transmitted according to the selected waveform parameters.

26. The apparatus of claim 25, wherein the instructions executable by the processor to cause the apparatus to select the waveform parameters are further executable to cause the apparatus to: a codeword is selected from a codebook comprising a plurality of codewords, wherein the codeword is indicative of a selected waveform parameter.

27. The apparatus of claim 26, wherein the instructions executable by the processor to cause the apparatus to select the waveform parameters are further executable to cause the apparatus to:

identifying a set of codewords for additional UEs within a threshold distance; and

The waveform parameters are changed for the at least one chirp to have a uniform distribution over a range such that the distance between the selected codeword and the identified codeword set is maximized.

28. The apparatus of claim 25, wherein the instructions executable by the processor to cause the apparatus to transmit the indication of the one or more selected waveform parameters are further executable to cause the apparatus to: the indication of the one or more selected waveform parameters is broadcast on one or more side communication channels between the UE and one or more additional UEs.

29. The apparatus of claim 25, wherein the instructions executable by the processor to cause the apparatus to transmit the indication of the one or more selected waveform parameters are further executable to cause the apparatus to: the indication of the one or more selected waveform parameters is transmitted on an uplink channel between the UE and a network entity.

30. The apparatus of claim 25, wherein the instructions are further executable by the processor to cause the apparatus to: information of a set of codewords being used in the vicinity of the UE is received from a network entity.

31. The apparatus of claim 25, wherein the instructions are further executable by the processor to cause the apparatus to: a beacon, an encoded discovery message, or a combination thereof is broadcast on one or more side communication channels between the UE and one or more additional UEs to indicate a location of the UE.

32. The apparatus of claim 25, wherein the instructions are further executable by the processor to cause the apparatus to: information of a set of codewords used by an additional UE is received over one or more multi-sided communication channels between the UE and one or more additional UEs, wherein the waveform parameters are changed based at least in part on the information of the set of codewords used by the additional UE.

33. The apparatus of claim 32, wherein the instructions are further executable by the processor to cause the apparatus to:

Receiving a set of beacons, encoded discovery messages, or a combination thereof for the additional UE on the one or more side communication channels between the UE and the one or more additional UEs to indicate a location of the additional UE; and

A set of proximity values for the additional UE relative to the UE is determined, wherein the waveform parameters are changed based at least in part on the set of proximity values for the additional UE.

34. The apparatus of claim 25, wherein the selected waveform parameters comprise a frequency range, a chirp duration, a frequency offset, or a combination thereof.

35. The apparatus of claim 25, wherein the instructions are further executable by the processor to cause the apparatus to:

identifying a range of interest of an interference source for the radar waveform; and

The frequency offset of the radar waveform is set such that interference peaks of at least one interference source occur outside the range of interest.

36. The apparatus of claim 25, wherein the instructions are further executable by the processor to cause the apparatus to: one or more chirps of the radar waveform are phase encoded to avoid coherent superposition of the chirps with other radar waveforms in the communication system.

37. A non-transitory processor-readable storage medium having stored thereon processor-executable instructions configured to cause a processor of an apparatus to suppress interference with radar in a communication system, the suppression being implemented by a User Equipment (UE), the processor-executable instructions configured to cause the processor to:

Selecting a waveform parameter for transmitting a radar waveform, the waveform parameter being a slope, a frequency offset, a duration of a chirp of the radar waveform, or a combination thereof, wherein the radar waveform comprises a plurality of chirps, and the selecting comprises changing the waveform parameter for at least one of the plurality of chirps;

Transmitting an indication of one or more selected waveform parameters over the communication system; and

The radar waveform is transmitted according to the selected waveform parameters.

38. The non-transitory processor-readable storage medium of claim 37, wherein the processor-executable instructions configured to cause the processor to select the waveform parameters are further configured to cause the processor to: a codeword is selected from a codebook comprising a plurality of codewords, wherein the codeword is indicative of a selected waveform parameter.

39. The non-transitory processor-readable storage medium of claim 38, wherein the processor-executable instructions configured to cause the processor to select the waveform parameters are further configured to cause the processor to:

identifying a set of codewords for additional UEs within a threshold distance; and

The waveform parameters are changed for the at least one chirp to have a uniform distribution over a range such that the distance between the selected codeword and the identified codeword set is maximized.

40. The non-transitory processor-readable storage medium of claim 37, wherein the processor-executable instructions configured to cause the processor to transmit the indication of the one or more selected waveform parameters are further configured to cause the processor to: the indication of the one or more selected waveform parameters is broadcast on one or more side communication channels between the UE and one or more additional UEs.

41. The non-transitory processor-readable storage medium of claim 37, wherein the processor-executable instructions configured to cause the processor to transmit the indication of the one or more selected waveform parameters are further configured to cause the processor to: the indication of the one or more selected waveform parameters is transmitted on an uplink channel between the UE and a network entity.

42. The non-transitory processor-readable storage medium of claim 37, wherein the processor-executable instructions are further configured to cause the processor to: information of a set of codewords being used in the vicinity of the UE is received from a network entity.

43. The non-transitory processor-readable storage medium of claim 37, wherein the processor-executable instructions are further configured to cause the processor to: a beacon, an encoded discovery message, or a combination thereof is broadcast on one or more side communication channels between the UE and one or more additional UEs to indicate a location of the UE.

44. The non-transitory processor-readable storage medium of claim 37, wherein the processor-executable instructions are further configured to cause the processor to: information of a set of codewords used by an additional UE is received over one or more multi-sided communication channels between the UE and one or more additional UEs, wherein the waveform parameters are changed based at least in part on the information of the set of codewords used by the additional UE.

45. The non-transitory processor-readable storage medium of claim 44, wherein the processor-executable instructions are further configured to cause the processor to:

Receiving a set of beacons, encoded discovery messages, or a combination thereof for the additional UE on the one or more side communication channels between the UE and the one or more additional UEs to indicate a location of the additional UE; and

A set of proximity values for the additional UE relative to the UE is determined, wherein the waveform parameters are changed based at least in part on the set of proximity values for the additional UE.

46. The non-transitory processor-readable storage medium of claim 37, wherein the selected waveform parameters comprise a frequency range, a chirp duration, a frequency offset, or a combination thereof.

47. The non-transitory processor-readable storage medium of claim 37, wherein the processor-executable instructions are further configured to cause the processor to:

identifying a range of interest of an interference source for the radar waveform; and

The frequency offset of the radar waveform is set such that interference peaks of at least one interference source occur outside the range of interest.

48. The non-transitory processor-readable storage medium of claim 37, wherein the processor-executable instructions are further configured to cause the processor to: one or more chirps of the radar waveform are phase encoded to avoid coherent superposition of the chirps with other radar waveforms in the communication system.