International Journal of Computer and Information Technology (ISSN: 2279 – 0764) Volume 04 – Issue 04, July 2015 www.ijcit.com 689 A Review of MC-CDMA Based Broadband Power Line Communications Systems Daniel Ngondya * , Justinian Anatory School of Informatics University of Dodoma * Email: dngondya [AT] gmail.com Abdil Rashid Mohamed Computer Science and Engineering Department University of Dar es Salaam Abstract— A number of MC-CDMA-based BPLC systems have been proposed-differing in terms of complexity and performance. This work comprehensively reviews MC-CDMA-based BPLC solutions, indicating similarities, differences, advantages and disadvantages of each. The solutions have been classified into two: conventional MC-CDMA-based BPLC solutions and MC- CDMA-based BPLC solutions with MAI reduction techniques. A total of 5 solutions have been summarized. Keywords-MC-CDMA; Broadband Power Line Communications; Last Mile Connectivity; Access Networks; Outdoor Power Line Communications I. INTRODUCTION Ubiquitous existence of power lines provides an excellent opportunity to redress rural communication infrastructure constraints. Power lines were not meant to carry data, but electricity. Power lines‟ characteristics such as frequency selective fading, high attenuation at high frequencies and impulsive noise are hostile to communications[1]. To achieve Broadband Power Line Communication (BPLC), the characteristics call for sophisticated modulation schemes to be used. Orthogonal Frequency Division Multiplexing (OFDM) has been used in a number of works to investigate viability of BPLC. However, recently, Multi-carrier Code Division Multiple Access (MC-CDMA) has been gaining popularity as it combines the best features of OFDM and Code Division Multiple Access (CDMA) to attain spectral efficiency, support multiple users and attain high data rates. MC-CDMA is robust against frequency selective fading and Inter-symbol Interference (ISI)[2]. However, MC-CDMA is affected by Multiple Access Interference (MAI) in frequency selective fading channels[3]. MC-CDMA-based BPLC is capable of transmitting data through low and medium voltage power line networks and therefore extend the reach of telecommunication services to remote areas at a relatively low cost. This work reviews various studies regarding MC-CDMA-based BPLC systems, identifying similarities and differences, also advantages and disadvantages. The rest of the work is organized as follows: Section II presents the characteristics of the Power Line Communication (PLC) channel and its standardization efforts. Section III presents an MC-CDMA-based BPLC system, how it works, categories, similarities, differences, advantages and disadvantages of various solutions. Finally, Section IV provides some conclusions. II. PLC CHANNEL A. Standardization At high frequencies, a PLC channel acts as an antenna emitting electromagnetic waves and can therefore interfere with other nearby communication services. PLC must therefore be standardized if they are to be used to offer broadband communication services. A draft standard with Physical and Media Access Control Layers specification for BPLC has already been ratified (in 2010) by IEEE. The standard (IEEE1901-2010) indicates data rates of up 500Mbps for transmission frequencies below 100MHz[4]. However, the standard is yet to be adopted by most countries‟ regulatory authorities. B. Topology of Power Line Networks The electrical power supply system can be broadly categorized into three network levels, namely: high-voltage, medium-voltage, and, low-voltage that can be employed as transmission medium for implementation of PLC technology. Fig. 1 illustrates the topology of the power-line network. Among the three categories, low voltage network is of interest as it can be used as “last mile” access network. The access network can be connected to the backbone network through conventional communication links such as fiber-optic, radio relay links, or even, the medium voltage network. The connection is normally done at the secondary substation (transformer). It can also be done anywhere else in the network. All customers are connected to the access network through a distribution cable and so the low-voltage network is a shared medium (logical bus topology).