MMSE detection method for spread-spectrum OFDMA communication system

Abstract

The invention provides an MMSE detection method for a spread-spectrum OFDMA communication system. The code spread factor of the spread-spectrum OFDMA communication system is Ns, and the payload is L, wherein L is more than or equal to half NS and less than or equal to Ns; and a code spread matrix with the size of Ns*L is formed by the first L columns of an original matrix w with the size of Ns*Ns. The method comprises the following steps of: a, performing OFDM demodulation and receiving to acquire a received symbol r; b, performing channel estimation, forming a diagonal matrix lambda h by Ns channel estimations, and estimating noise power sigma 2; c, calculating an MMSE detection operator BL when the payload is L, wherein the step c comprises the following substeps of: c.1, calculating an MMSE detection operator c when the payload is Ns; and c.2, recurring in turn according to a recursion rule to acquire a recursion rule: for given BL', first decomposing BL' in a way that QL' is a matrix composed of the first (L'-1) columns of the BL', and qL' is the last row of the BL'; and then calculating BL'-1, wherein WL' is the L' th column of w; and d, calculating a detection symbol y. The MMSE detection method adopts a recursion method, avoids direct matrix inversion, greatly reduces the calculation amount and reduces the power consumption of detecting hardware.

Description

Technical field The present invention relates to the field of wireless communication, in particular to an MMSE detection method of a spread spectrum OFDMA communication system. Background technique Orthogonal Frequency Division Multiple Access (OFDMA) is a multi-carrier access method based on OFDM. Its principle is to sub-carrierize the channel. Each user selects a part of the sub-carrier and uses OFDM for transmission. As long as sufficient time interval (cyclic prefix) is left, the orthogonality between sub-carriers is not subject to multipath delay, and signals of different users hardly interfere with each other. Spread spectrum is a special symbol transformation, which changes one symbol into multiple symbols and transmits them over a wider frequency band to obtain better robustness. For example, Code Division Multiple Access (CDMA) is based on spread spectrum technology. The information data to be transmitted with a certain signal bandwidth is modulated with a high-speed ...

AI Technical Summary

Problems solved by technology

Since the traditional MMSE detection method needs to do matrix inversion operation, when N s / 2≤L≤N s When , the amount of calculation will be quite large, resulting in a considerable power consumption of the detection hardware

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