FIELD OF TECHNOLOGY

The following relates generally to wireless communications and more specifically to inter-radio access technology interference cancellation.

BACKGROUND

Wireless communications 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 capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include fourth generation (4G) systems such as Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems, and fifth generation (5G) systems which may be referred to as New Radio (NR) systems. These systems may employ technologies such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM). A wireless multiple-access communications system may include a number of base stations or network access nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE).

Wireless communication systems may include or support networks used for vehicle based communications, also referred to as vehicle-to-everything (V2X) networks, vehicle-to-vehicle (V2V) networks, cellular V2X (CV2X) networks, or other similar networks. During CV2X communications, a UE may decode transmissions generated by a UE operating in the CV2X network. However, in some instances, transmissions from one or more radio access technologies (RATs) different than CV2X may interfere with the transmission in the CV2X network. Under these conditions, the CV2X transmission may be degraded such that the receiving UE may not correctly decode the CV2X transmission.

SUMMARY

The described techniques relate to improved methods, systems, devices, and apparatuses that support inter-radio access technology interference cancellation. Generally, the described techniques provide for an interference estimation process that efficiently measures interference from radio access technologies (RATs) different from cellular vehicle-to-everything (CV2X) such as wireless local area network (WLAN), which may also be referred to herein as WIFI, or Long Term Evolution (LTE). For instance, a UE may take interference measurements when no CV2X signal is transmitted. This may be during the last symbol of a subframe immediately prior to the subframe of interest. For example, UE may assume that no CV2X signal is present in symbol 13 of a subframe and may detect the WIFI interference in that symbol. Then, the UE may estimate the noise plus WIFI interference measured during symbol 13 to improve noise plus interference whitening in the subsequent subframe. In some cases, this estimation and mitigation of interference may occur for every subframe. For example, an estimation may occur at symbol 13 of subframe n−1 and applied to subframe n, an estimation may occur at symbol 13 of subframe n and applied to subframe n+1, and so on. Additionally, a UE may estimate LTE interference for improved decoding of subframe n. For example, the UE may buffer the first thirteen symbols of a subframe (e.g., symbols 0 to 12 of subframe n) and then measure and estimate LTE interference throughout the fourteenth symbol (e.g., symbol 13). The UE may then decode the stored symbols of subframe n based on the LTE interference measurement.

A method of wireless communications by a UE is described. The method may include identifying, within a first transmission time interval (TTI), a symbol period in which a set of wireless devices operating in accordance with a cellular vehicle to everything (CV2X) RAT are configured to refrain from transmitting, measuring interference of a second RAT during the symbol period, the second RAT differing from the CV2X RAT, and decoding a CV2X waveform during the first TTI or a second TTI based on the measured interference.

An apparatus for wireless communications by a UE is described. The apparatus may include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to identify, within a first TTI, a symbol period in which a set of wireless devices operating in accordance with a cellular vehicle to everything (CV2X) RAT are configured to refrain from transmitting, measure interference of a second RAT during the symbol period, the second RAT differing from the CV2X RAT, and decode a CV2X waveform during the first TTI or a second TTI based on the measured interference.

Another apparatus for wireless communications by a UE is described. The apparatus may include means for identifying, within a first TTI, a symbol period in which a set of wireless devices operating in accordance with a cellular vehicle to everything (CV2X) RAT are configured to refrain from transmitting, measuring interference of a second RAT during the symbol period, the second RAT differing from the CV2X RAT, and decoding a CV2X waveform during the first TTI or a second TTI based on the measured interference.

A non-transitory computer-readable medium storing code for wireless communications by a UE is described. The code may include instructions executable by a processor to identify, within a first TTI, a symbol period in which a set of wireless devices operating in accordance with a cellular vehicle to everything (CV2X) RAT are configured to refrain from transmitting, measure interference of a second RAT during the symbol period, the second RAT differing from the CV2X RAT, and decode a CV2X waveform during the first TTI or a second TTI based on the measured interference.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, identifying the symbol period may include operations, features, means, or instructions for identifying a preconfiguration or receiving control signaling that configures the UE to refrain from transmitting during the symbol period.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, identifying the symbol period may include operations, features, means, or instructions for identifying that the symbol period may be a last symbol period of the first TTI, the first TTI including a set of symbol periods.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, measuring the interference may include operations, features, means, or instructions for generating, for the symbol period, a set of interference measurements using a set of antennas of the UE, and generating a covariance interference metric based on the set of interference measurements, where the CV2X waveform may be decoded based on the covariance interference metric.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for buffering samples of the CV2X waveform generated for a set of symbol periods of the first TTI that occur prior to the symbol period within the first TTI, where the CV2X waveform may be received during the first TTI and decoded based on the buffered samples.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, measuring the interference may include operations, features, means, or instructions for generating an interference power measurement for the symbol period, where the CV2X waveform may be decoded based on the interference power measurement.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, measuring the interference may include operations, features, means, or instructions for generating a noise statistic, an interference statistic, or both, for the symbol period, where the CV2X waveform may be decoded based on the noise statistic, the interference statistic, or both.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, decoding the CV2X waveform may include operations, features, means, or instructions for decoding the CV2X waveform in the second TTI that occurs after the first TTI based on the measured interference.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the second TTI occurs immediately after the first TTI.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, at least one intervening TTI occurs between the first TTI and the second TTI.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, decoding the CV2X waveform may include operations, features, means, or instructions for applying noise whitening processing to the CV2X waveform based at least in interference measurement.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, decoding the CV2X waveform may include operations, features, means, or instructions for decoding the CV2X waveform in the first TTI.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, measuring the interference may include operations, features, means, or instructions for measuring, for the symbol period, interference of at least one additional RAT, where the CV2X waveform may be decoded based on the measured interference of the at least one additional RAT.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for measuring interference within a second symbol period, where the CV2X waveform may be decoded based on the interference measured within the second symbol period.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, measuring the interference may include operations, features, means, or instructions for measuring, during the symbol period, the interference of a WLAN RAT.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, measuring the interference may include operations, features, means, or instructions for measuring, during the symbol period, the interference of an LTE RAT.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the first TTI may be a subframe.

