Method for cooperating relays to form beams based on limited feedback

Abstract

The invention relates to a method for cooperating relays to form beams based on limited feedback, which is applicable to a communication system. The communication system comprises an transmitter, a plurality of relays and a receiver; the transmitter is configured with a plurality of antennas; each relay is configured with single antenna; the receiver is configured with a plurality of antennas; a plurality of relays cooperate mutually and adopt amplifying and retransmission protocol; the whole communication process is finished in two time slot; in a first time slot, the transmitter broadcasts data flow to all the relays after the transmitting beams are formed; in a second time slot, all the relays determine the code words formed by distributed beams according to limited feedback information containing code word labels and power amplified factors from the receiver; then the plurality of relays transmit the received signals to information sink after component handling of respective code word; the design of a codebook is finished by a codebook design and code word updating algorithm, the relays select code words which can lead the instantaneous signal to noise ratio of the receiver to be maximum as beams according to each channel condition so as to form vectors.

Description

technical field [0001] The invention relates to a beam forming method applied to a wireless communication system, in particular to a limited feedback-based cooperative relay beam forming method, which belongs to the field of wireless communication. Background technique [0002] Relay-assisted cellular wireless communication systems have the advantages of extending cell coverage, improving spectrum efficiency of cell edge users, and overcoming shadow fading. In recent years, researchers have studied relay communication from the perspectives of relay protocols, information theory, and processing algorithms. For example, for single-input single-output (SISO) wireless relay communication systems, there are three typical Relay protocols, namely Amplify-and-Forward (AF), Decode-and-Forward (DF) and Compress-and-Forward (CF), where the AF relay protocol does not require decoding Directly forwarding signals, the processing complexity and power consumption are very low, so it is mor...

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Problems solved by technology

[0004] Current research usually assumes that each relay must obtain the ideal Channel State Information (CSI), and then due to the inaccurate channel estimation of the receiver, the time delay of channel information feedback, and noise pollution, this assumption is not valid. The realistic, more practical case is that the relay only knows part of the CSI

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