Bandwidth-Efficient Selective Retransmission for MIMO-OFDM Systems

Abstract

In this work, we propose an efficient selective retransmission method for multiple-input and multipleoutput (MIMO) wireless systems under orthogonal frequency-division multiplexing (OFDM) signaling. A typical received OFDM frame may have some symbols in error, which results in a retransmission of the entire frame. Such a retransmission is often unnecessary, and to avoid this, we propose a method to selectively retransmit symbols that correspond to poor-quality subcarriers. We use the condition numbers of the subcarrier channel matrices of the MIMO-OFDM system as a quality measure. The proposed scheme is embedded in the modulation layer and is independent of conventional hybrid automatic repeat request (HARQ) methods. The receiver integrates the original OFDM and the punctured retransmitted OFDM signals for more reliable detection. The targeted retransmission results in fewer negative acknowledgements from conventional HARQ algorithms, which results in increasing bandwidth and power efficiency. We investigate the efficacy of the proposed method for optimal and suboptimal receivers. The simulation results demonstrate the efficacy of the proposed method on throughput for MIMO-OFDM systems.

Channel Constrained Multiple Selective Retransmissions for OFDM System: BER and Throughput Analysis

“…Selective retransmission method in [23] embeds a retransmission sub-layer in PHY for single-input single-output OFDM (SISO-OFDM) system. For a MIMO-OFDM system, selective retransmission using channel condition number as sub-carrier quality measure is proposed in [24]. Significant throughput gain in [25] is observed for selective retransmission using orthogonal space-time block (OSTB) code [26].…”

“…The proposed CNSR method requests retransmission of OFDM sub-carriers of the failed packet, which have low SNR instead of full retransmission. Furthermore, methods in [23], [24], and [26] did not optimize amount of information to be retransmitted selectively with objective to enhance spectral efficiency. The proposed CNSR method optimizes threshold on accumulated norm of gains of the OFDM sub-carriers of the failed packet for selective retransmission.…”

Design of encrypted transceiver Non-coherent OFDM with ability to correct coding bits of information

“…FDMimplication conflicts the fading over a multi-track trough yet permits little-intricacy receiver design. (DE) via hesitancy eclectic channels using OFDM description is suggested in [11,12].…”

MIMO Channel Capacity and Configuration Selection for Switched Parasitic Antennas

“…However, it does not give any indication about the quality of the channel matrix, whether it is a well‐conditioned or ill‐conditioned channel. CN indicates the channel quality , and is related to the EVS of the channel matrix. A high EVS indicates that the channel is correlated with a high condition number, and this is referred to as an ill‐conditioned channel matrix.…”