Fast codeword selection for limited feedback beamforming multiple‐input–multiple‐output systems using breadth‐first tree search

Abstract

Codebooks with constant modulus entries are being considered for the limited feedback beamforming multiple-inputmultiple-output (MIMO) system to improve the power amplifier efficiency at the transmitter. Assume that one such codebook is known to both the transmitter and receiver. The receiver must determine a target codeword from this codebook and send its index back to the transmitter. A receiver can be implemented with low cost if fast codeword selection algorithm is executed. In this study, the authors utilise the properties possessed by three such codebooks and propose a novel tree search algorithm for fast codeword selection. Compared with two previously reported codeword selection algorithms, our algorithm is of fixed complexity and does find the target codeword. Furthermore, our algorithm for codeword selection is similar to the tree search for MIMO detection. These two similar tree search algorithms for both codeword selection and MIMO detection can be implemented by the same hardware architecture. A baseband receiver with small chip area for the dual-mode (the spatial multiplexing and beamforming transmission modes) MIMO system is possible.

Block-Wise QR-Decomposition for the Layered and Hybrid Alamouti STBC MIMO Systems: Algorithms and Hardware Architectures

“…Thus, using PE #1, PE #2, BRU, and proper reduced PEs according to Table IV, we can have a TSA architecture to compute the QRD of for a parameter set ( ). As the MIMO techniques prevail, current receiver design may consider signal detection for not only the well-studied SDM but also the advanced Alamouti STBC [43] or precoding [44], [45] MIMO techniques. Assume that there are antennas and radio frequency chains available at the receiver.…”

Implementation of the precoder matrix indicator selection using MMSE trace criterion for the downlink transmission in LTE

“…Two different ways have been adopted by the IEEE 802.11n/ac WLAN [3] and LTE [4][5][6][7][8] to reduce the amount of CSI information. In IEEE WLAN, the precoding matrix associated with each sub-carrier is determined from the singular value decomposition of the channel matrix [9].…”

“…The nested property of the precoding matrices based on the Householder matrix was proposed to reduce the complexity of the selection algorithm [16][17][18]. Tree search algorithm to utilize the correlation between the precoding matrices was reported [8]. Cholesky factorization, selected FFT, and nested cofactor expansion schemes were used in [7] to reduce both the algorithm and hardware architecture.…”

Application of compressive sensing to limited feedback strategy in large‐scale multiple‐input single‐output cellular networks

“…In [6], the quantisation accuracy was optimised by adaptively allocating the feedback bits. In [7], Liu et al proposed a codeword selection method based on the breadth-first tree search algorithm. Another popular approach solves the problem through beamforming VQ rather than channel quantisation.…”