Channel Statistics-Based RF Pre-Processing with Antenna Selection

Abstract

We introduce two novel joint radio-frequency (RF)-baseband designs for receivers in a MIMO system with N t transmit antennas, N r receive antennas, but only L < N r RF chains at the receiver. The joint design introduces an RF preprocessing matrix that processes the signals from the different antennas, and is followed by selection (if necessary), downconversion, and further processing in the baseband. The schemes are similar to conventional antenna selection in that they use fewer RF chains than antenna elements, but achieve superior performance by exploiting the spatial correlation of the received signals. The first of our proposed designs uses an L × N r RF pre-processing matrix that outputs only L streams followed by baseband signal processing, and, thus, eliminates the need for a selection switch. The second one uses an N r × N r RF preprocessing matrix that outputs N r streams and is followed by a switch that selects L streams for baseband signal processing. Both spatial diversity and spatial multiplexing systems are considered and the optimum pre-processing matrices are derived for all cases. To accommodate practical RF design constraints, which prefer a variable phase-shifter-based implementation, a suboptimal phase approximation is also introduced. Performance better than conventional antenna selection and close to the full complexity receiver is observed in both single cluster and multi-cluster wireless channels. A beam-pattern-based geometric intuition is also developed to illustrate the effectiveness of the optimal solutions.

Pre‐LNA smart soft antenna selection for MIMO spatial multiplexing/diversity system when amplifier/sky noise dominates

“…Thereafter, we show when the number of the receive terminals, i.e. RF chains, is greater than or equal to the number of transmit terminals, the pre-LNA SAS can even outperform a full-complexity MIMO which is an upper bound for post-LNA SAS [14] and pre-LNA SAS with the sky noise dominance [15]. In subsequent section, we verify this result using computer simulations.…”

Iterative Matrix Decomposition Aided Block Diagonalization for mm-Wave Multiuser MIMO Systems

“…Since employing digital BF for a large number of antennas imposes a high system complexity, a hybrid architecture that uses analog phase shifters in conjunction with a reduced number of radio frequency (RF) chains is conceived [7]- [14], [29], [30]. Beamforming using this hybrid architecture is often referred to as hybrid beamforming (HBF).…”

Maximum-SNR transmit antenna selection with two receive antennas is polynomially solvable

“…All these works present suboptimal algorithms, since the optimal solution is considered to require the evaluation of the metric of interest over all (Z) possible combinations of AS sets, where N and K are the numbers of available and selected, respectively, antennas. Due to the exponential complexity of the exhaustive-search maximum-predetection-SNR AS, a suboptimal hybrid algorithm that performs RAS to maximize the receiver pre detection SNR with complexity D(N) was considered in [16] where the authors design the beamforming vector at the transmitter side as the principal right singular vector of the full channel matrix.…”