Abstract

We address the problems at the most critical area in a cellular multicarrier code division multiple access (MC-CDMA) network, namely, the cell border. At a mobile terminal the diversity can be increased by using transmit diversity techniques such as cyclic delay diversity (CDD) and space-time coding like Alamouti. We transfer these transmit diversity techniques to a cellular environment. Therefore, the performance is enhanced at the cell border, intercellular interference is avoided, and soft handover procedures are simplified all together. By this, macrodiversity concepts are exchanged by transmit diversity concepts. These concepts also shift parts of the complexity from the mobile terminal to smart base stations.

Highlights

  • The development of future mobile communications systems follows the strategies to support a single ubiquitous radio access system adaptable to a comprehensive range of mobile communication scenarios

  • Two different positions of the mobile terminal (MT) are chosen: directly at the cell border (C/I = 0 dB) and closer to one base stations (BSs) (C/I = 10 dB). Both transmit diversity schemes suffer from the increased multiple-access interference (MAI) for higher resource loads which is in the nature of the used multicarrier code division multiple access (MC-code division multiple access (CDMA)) system

  • This paper handles the application of transmit diversity techniques to a cellular MC-CDMA-based environment

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Summary

INTRODUCTION

The development of future mobile communications systems follows the strategies to support a single ubiquitous radio access system adaptable to a comprehensive range of mobile communication scenarios. A simple transmit diversity technique is to combat flat fading conditions by retransmitting the same signal from spatially separated antennas with a frequency or time offset. The main approach of this paper is the use and investigation of transmit diversity techniques in a cellular environment to achieve macrodiversity in the critical cell border area. In addition to OFDM, spread spectrum, namely, code division multiple access (CDMA), gives high flexibility due to simultaneous access of users, robustness, and frequency diversity gains [14]. The proposed techniques C-CDD and CAT are applied to a cellular environment based on an MCCDMA transmission scheme.

MC-CDMA system
Cellular environment
TRANSMIT DIVERSITY TECHNIQUES FOR CELLULAR ENVIRONMENT
Resumefor C-CDD and CAT
RESULTING CHANNEL CHARACTERISTICS FOR C-CDD
40 Sub-carrier 20
SIMULATION RESULTS
C-CDD performance
Section 4.
CAT performance
MAI and throughput performance of C-CDD and CAT
CONCLUSIONS

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