Performance of multicarrier complementary-coded CDMA under frequency-selective Nakagami-m fading channels

D Judson,A Albert Raj

doi:10.1186/s13638-016-0563-y

Abstract

Multicarrier complementary-coded code division Multiple Access (MC CC-CDMA) is becoming an attractive multiple access technique for high data rate transmission in future wireless communication systems. MC CC-CDMA systems transmitting over frequency-selective channels suffer from multiple access interference (MAI) owing to non-ideal correlation properties of complementary codes (CC). MC CC-CDMA with equalization has recently gained much attention for its ability to offer an excellent performance than traditional systems in frequency-selective fading channels. In this paper, the authors present an analytical study and investigation of MC CC-CDMA downlink system using different combining schemes. The use of parallel interference cancellation (PIC) under frequency-selective Nakagami-m fading channels is also analyzed. A comparison among different combining schemes is provided to show the impact of PIC with minimum mean square error combining (MMSEC) and maximal ratio combining (MRC) on the performance of MC CC-CDMA system. The analytical and simulation results show that the combination of general combining schemes with PIC provides an efficient solution to suppress MAI in downlink MC CC-CDMA system than conventional MC-CDMA systems using Walsh codes under frequency-selective channels.

Highlights

Generation wireless communication is expected to provide multimedia services with different quality of service, offering high throughput and reliability under limited power and bandwidth resources
The rest of the paper is organized as follows: in Section 2, we describe the system model of MC CCCDMA system under frequency-selective Nakagami-m fading channels
5 Conclusions In this paper, we analyzed the performance of MC complementary codes (CC)-Code division multiple access (CDMA) system with different combining schemes for downlink transmissions under frequency-selective Nakagami-m fading channels

Summary

Introduction

Generation wireless communication is expected to provide multimedia services with different quality of service, offering high throughput and reliability under limited power and bandwidth resources. In order to achieve interference-free OCC, the flock size of the signature code must be equal to the set size of the codes This problem was addressed in [9] where the code generated was able to support more users compared to complete complementary codes. The ideal orthogonality of complementary correlation function under frequency-selective fading channels is lost due to multiple access interference and multipath interference existing between users transmitting over a common bandwidth. Even though channel selectivity reduces orthogonality of CC, the multi-sequence spreading and summation at the receiver of MC CC-CDMA system offers additional diversity gain which cannot be achieved in traditional CDMA systems using single carrier. The impacts of different combining schemes such as ORC, MRC, and MMSEC on bit error rate (BER) performance of CC-CDMA are examined under frequency-selective fading channels.

MC CC-CDMA transmitter descriptions

Conclusions