Performance of Power Line Communication Systems Using MC-CDMA Transmission Techniques 1 Yung-Fa Huang, 2 Tan-Hsu Tan, 3 Chia-Hsing Cheng and 4 Neng-Chung Wang 1 Graduate Institute of Networking and Communication Engineering Chaoyang University of Technology, Taiwan 2 Department of Electrical Engineering, National Taipei University of Technology, 3 Department of Computer and Communication Engineering, Chaoyang University of Technology, Taiwan 4 Department of Computer Science and Information Engineering, National United University, Taiwan Abstract: - In this paper, the performance improvement in multi-carrier direct-sequence code-division multiple-access (MC-CDMA) power line communication (PLC) systems using partial parallel interference cancellation (PPIC) multiuser detectors is investigated. The high data rate demanded in the multimedia PLC systems can be offered by the MC-CDMA systems. However, the multiple access interferences (MAIs) exist in the frequency selective fading channels for the down link even though using an orthogonal PN code and occur for the up link due to the non-orthogonal spreading codes. In the high system load, the MAIs become the dominant factor degrading the performance. Therefore, the performance of a multistage PPIC is further investigated for the MC-CDMA PLC systems. Simulation results show that with adequate cancellation weights, the PPIC scheme can obtain a superior performance than the conventional PIC scheme, especially at heavy system load. Furthermore, with the BER requirements of 0.001, the five-stage PPIC with PCWs, 0.7, 0.8, 0.9 and 1 for stage 2, 3, 4 and 5, respectively, increases the capacity from 15 of CPIC to 19 users with the processing gain 32 over the power line channels. Key-Words: - MC-CDMA, PLC, Multiuser detectors, Partial parallel interference cancellation 1 Introduction The orthogonal frequency division multiplexing (OFDM) supports high rate data transmission. The conventional direct-sequence code-division multiple-access (DS-CDMA) can give a high potential capacity for the multiple access communication systems [1]. Therefore, the combined technique of OFDM and CDMA, multi-carrier code-division multiple-access (MC-CDMA) communication technique, which exploits the spreading feature of CDMA but without the adverse effect of increasing frequency selectivity in the channel, has received much attention among researcher and been adored as a favorite candidate for 4th generation cellular communication systems [2-5]. Powerline Communication (PLC), a communication technique that uses the existing power wiring (120 Volts, 240, etc…) to carry information, has attracted much attention and has become a mature subject of research in last few years due to its low cost and high availability. Powerline communication could offer ideal solutions, mainly because the power supply infrastructure is denser than any other communication network [6-8]. The full infrastructure from the provider to the home wall plug is there, ready for use without any additional installation cost. Although the powerline network has not been designed for transferring data and is thus characterized by unfavorable transmission properties, frequency ranges of some MHz are at the disposal for telecommunication purposes. To achieve high data rates of some Mbit/s required for multimedia applications, sophisticated and well-designed digital transmission systems are necessary in order to exploit the available frequency bands [8]. Therefore, by using multi-carrier modulation, CDMA signal is spread over several carriers by which frequency diversity over the power lines is achieved similar to path diversity in RAKE receivers. The multiple narrowband channels in each subcarrier undergo nearly frequency flat fading. A suitable guard time can be inserted to eliminate the effect of delay spread. Then, with a sufficient cyclic extension, the PN codes spreading in each subcarrier can keep 12th WSEAS International Conference on COMMUNICATIONS, Heraklion, Greece, July 23-25, 2008 ISSN: 1790-5117 135 ISBN: 978-960-6766-84-8