Reduced parallel and pipelined high-order mimo lmmse receiver architecture

Abstract

Disclosed is a LMMSE receiver that restores orthogonality of spreading codes in the downlink channel for a spread spectrum signal received over N receive antennas. The FFT-based chip equalizer tap solver reduces the direct matrix inverse of the prior art to the inverse of some submatrices of size NxN with the dimension of the receive antennas, and most efficiently reduces matrix inverses to no larger than 2x2. Complexity is further reduced over a conventional Fast Fourier Transform approach by Hermitian optimization to the inverse of submatrices and tree pruning. For a receiver with N=4 or N=2 with double oversampling, the resulting 4x4 matrices are partitioned into 2x2 block sub-matrices, inverted, and rebuilt into a 4x4 matrix. Common computations are found and repeated computations are eliminated to improve efficiency. Generic design architecture is derived from the special design blocks to eliminate redundancies in complex operations. Optimally, the architecture is parallel and pipelined.

Description

technical field [0001] The present invention relates generally to receivers and related methods for spread spectrum communication systems using multiple transmit antennas and / or multiple receive antennas, and in particular to the use of equalizers such as those based on Linear Minimum Mean Square Error (LMMSE). equalizer receiver. Background technique [0002] MIMO (Multiple Input Multiple Output) technology using multiple antennas on both the transmitter and receiver sides has recently emerged as one of the most important technological breakthroughs in modern communications. The original MIMO is called D-BLAST (see G.J.Foschini, "Layered space-time architecture for wireless communication in a fading environment when using multielement antennas", Bell Labs Tech.J., pp.41-59, 1996), and a A more realistic strategy for nullification and elimination with a reasonable trade-off between complexity and performance is called V-BLAST (see G.D. COMMUNICATION ARCHITECTURE", Electron...

AI Technical Summary

Problems solved by technology

Although this FFT-based algorithm avoids the inversion of the original correlation matrix of dimension NF×NF, the inventors believe that some matrix inversions are unavoidable for MIMO receivers

For MIMO receivers with high dimensions, the complexity of the MIMO receiver increases significantly with the number of antennas

Images