Abstract

Multiple Input and Multiple Output (MIMO) systems use multiple antennas at both transmitter and receiver ends for increasing link capacity and spectral efficiency. However, combining schemes used for such systems face critical issues such as presence of interference, signals to interference and noise ratios (SINRs) and complexity. To overcome the asserted issues; in this paper linear multiuser detection techniques are employed in over loaded MIMO systems where the number of transmit antennas (\(\varvec{N_t}\)) is greater than number of receiver antennas (\(\varvec{N_r}\)), using Hybrid Automatic Repeat request with Incremental Redundancy (HARQ IR). The primary aim of this research is to enhance bit error rate (BER) and throughput by transforming an overloaded MIMO systems (\(\varvec{N_t>N_r}\)) into critically loaded system (\(\varvec{N_t=N_r}\)) or under loaded MIMO systems (\(\varvec{N_t<N_r}\)) by simple retransmission method. Simulation results show unprecedented performance compared to contemporary approaches in term of throughput and BER.

Highlights

  • We proposed a different approach by modifying his method and used the concept of Hybrid Automatic Repeat request with Incremental Redundancy (HARQ IR) in overloaded Multiple Input and Multiple Output (MIMO) system

  • Number of kernel blocks retransmission at different SNR (Eb/No), bit error rate (BER) of hybrid automatic repeat request (HARQ) IR is less than BER of HARQ chase combining (HARQ Chase Combining (CC))

  • At SNR of 10 Eb/No, throughput of Scheme HARQ IR proposed is 0.75 as compared to HARQ CC which is 0.45 with joint maximum likelihood (JML) detection, it means throughput efficiency is improved by 20% for HARQ IR as compared to HARQ CC

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Summary

Introduction

Fifth generation (5G) systems are moving towards the concept of “device centric systems (DCS)” [1] in which many devices are transmitting and receiving at. Situation becomes more complex when transmitting antennas increases, leading it to complex situation where it is difficult to implement in practical scenario To resolve this issue, low complex MUD (multiuser detection) techniques are proposed for overloaded conditions [6]-[8]. The very focus of this research is to utilize HARQ IR scheme in overloaded MIMO system for enhancing data rate, throughput and at the same time using a simple and low complex technique for detection purpose. For this purpose, a scheme is proposed considering the concept of stacking retransmission.

Related Study
System Model
JML Detector
Suboptimal MMSE Detector
Proposed Scheme
HARQ IR Stacking
Performance Analysis
Bit Error Rate (BER) Analysis
Throughput Analysis
Findings
Conclusion
Full Text
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