Abstract: This application provides a training sequence transmission method and apparatus. The method includes: A first AP broadcasts a trigger frame, where the trigger frame indicates a time sequence of separately sending channel sounding frames by N STAs, and N is an integer greater than 1. The first AP receives the channel sounding frames sequentially sent by the N STAs, where one channel sounding frame includes one or more training sequences. In this solution, only one trigger frame needs to be sent, so that the N STAs can be triggered to separately report channel sounding frames to M+1 APs. However, in the conventional technology, each AP needs to send one channel training request to each STA, that is, N×(M+1) channel training requests are sent in total, to trigger each STA to report a training sequence. Therefore, this solution can significantly reduce signaling overheads.

Abstract: This application provides an uplink multi-station channel estimation method, a station (STA), and an access point (AP), which can be applied to an uplink multi-user multiple-input multiple-output scenario. The uplink multi-station channel estimation method includes: a STA generating a frame including a first group of training sequences and a second group of training sequences, and sending the frame to the AP. The AP calculates a frequency offset value between the STA and the AP based on the received first group of training sequences and the received second group of training sequences. The AP performs channel estimation based on the calculated frequency offset value. According to the technical solutions provided in this application, the AP can more accurately learn of frequency offset values between a plurality of STAs and the AP. This improves channel estimation precision.

Abstract: In an embodiment an interference cancellation method includes generating, by a first device, a first packet, wherein the first packet comprises a first group of elements, a second group of elements, and user data, the first group of elements being different from the second group of elements and sending, by the first device, the first packet to a second device by using at least one pair of subcarriers, wherein two subcarriers in the at least one pair of subcarriers are symmetrical with respect to a direct current subcarrier, and wherein the first packet is usable by the second device to cancel interference in the user data based on the first group of elements and the second group of elements.

Abstract: This application provides an uplink multi-station channel estimation method, a station (STA), and an access point (AP), which can be applied to an uplink multi-user multiple-input multiple-output scenario. The uplink multi-station channel estimation method includes: a STA generating a frame including a first group of training sequences and a second group of training sequences, and sending the frame to the AP. The AP calculates a frequency offset value between the STA and the AP based on the received first group of training sequences and the received second group of training sequences. The AP performs channel estimation based on the calculated frequency offset value. According to the technical solutions provided in this application, the AP can more accurately learn of frequency offset values between a plurality of STAs and the AP. This improves channel estimation precision.

Abstract: This application provides a training sequence transmission method and apparatus. The method includes: A first AP broadcasts a trigger frame, where the trigger frame indicates a time sequence of separately sending channel sounding frames by N STAs, and N is an integer greater than 1. The first AP receives the channel sounding frames sequentially sent by the N STAs, where one channel sounding frame includes one or more training sequences. In this solution, only one trigger frame needs to be sent, so that the N STAs can be triggered to separately report channel sounding frames to M+1 APs. However, in the conventional technology, each AP needs to send one channel training request to each STA, that is, N×(M+1) channel training requests are sent in total, to trigger each STA to report a training sequence. Therefore, this solution can significantly reduce signaling overheads.

Abstract: The present disclosure relates to signal sending methods and apparatus. One example method includes generating a first data signal based on channel state information, receiving a second data signal sent by a primary transmitter, determining a phase of the second data signal, and sending the first data signal based on a phase of a first measurement signal sent by the primary transmitter and the phase of the second data signal sent by the primary transmitter.

Abstract: This application discloses a channel estimation method and apparatus, a communications system, pertains to the field of communications technologies. The method is applied to an AP, includes: obtaining communication quality between the AP and a STA; determining, based on the communication quality, a quantity of channel estimations that need to be performed in a current round of TSCE; and obtaining channel state information CSI between the AP and the STA, where the CSI is determined based on a channel estimation result obtained after the current round of TSCE is performed based on the determined quantity of channel estimations. In this application, the AP adjusts, in real time based on the communication quality, a quantity of channel estimations that need to be performed in each round of TSCE, to resolve a problem of relatively low reliability of channel estimation in a related technology.

Abstract: The present disclosure relates to signal sending methods and apparatus. One example method includes generating a first data signal based on channel state information, receiving a second data signal sent by a primary transmitter, determining a phase of the second data signal, and sending the first data signal based on a phase of a first measurement signal sent by the primary transmitter and the phase of the second data signal sent by the primary transmitter.