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Kumaratharan, N.
- Multi Carrier-CDMA based SDR using Super Orthogonal Turbo Code
Authors
Source
Wireless Communication, Vol 5, No 2 (2013), Pagination: 87-91Abstract
Multi Carrier-CDMA, a combination of CDMA and OFDM has become a promising access technique for next generation wireless communication. It offers high speed data rate, flexible bandwidth allocation and enhanced performance to each user simultaneously. To further realize the benefits of MC-CDMA, it is made adaptable in the physical layer of software defined radio (SDR) where SDR is defined as a reconfigurable hardware with inbuilt software modules. Thus a MC-CDMA system based SDR is constructed which can be best suited for developing standards. However, as the number of users increases, due to overlapping of signals, orthogonality of the OFDM part is not maintained. It results in multiple access interference (MAI) which degrades the system performance in the downlink. To mitigate these effects, multi user detection techniques (MUD) is used. In this paper, MC-CDMA based SDR using super orthogonal turbo code (SOTC) is proposed and compared with MC-CDMA using Walsh Hadamard (WH) codes. The bit error rate (BER) is evaluated using the two codes and performance analysis is observed.
Keywords
MC-CDMA, SDR, SOTC Codes and WH Codes.
- Multilevel Prime Code for FH-CDMA System Over Rayleigh Fading Channels
Authors
1 Information Technology Department, Sri Venkateswara College of Engineering, Sriperumbudur, Tamil Nadu, IN
Source
Wireless Communication, Vol 4, No 7 (2012), Pagination: 337-341Abstract
Frequency hopping code division multiple access is a technique which provides high security in the wireless communication. Different types of code sequencing techniques are used for the frequency hopping. The prime codes are only coded in the time domain. However, the small code size becomes the major issue for one-dimensional codes. To deal with this limitation of one dimensional codes, a new family of two-dimensional codes is proposed. The new codes are modified from the well known prime-hop codes. Hence, it is referred as multilevel prime codes. The modified prime-hop codes preserve the same code correlation properties as the original prime-hop codes, i.e. the cross-correlating constraint is equal to one and the autocorrelation constraint is equal to zero, and can be generated with lower cost, lower complexity and lower power loss encoders/decoders.Keywords
Frequency Hopping-Code Division Multiple Access, Multilevel Prime Code, Multiple Access Interference, Prime Code.- Performance Enhancement of MC-CDMA Systems through MAP based Multiuser Detection
Authors
1 Department of Information technology, Sri Venkateswara College of Engineering, Sriperumbudur, Chennai, IN
2 Cognizant Technology Solutions, Chennai, IN
Source
International Journal of Advanced Networking and Applications, Vol 3, No 6 (2012), Pagination: 1438-1443Abstract
The joint Multiuser Detection (MUD) and turbo coding are the two powerful techniques for enhancing the performance of the MC-CDMA systems. The Multiple Access Interference (MAI) is one of the factors that affect the Bit Error Rate (BER) performance of the MC-CDMA systems. Maximum a posteriori (MAP) criterion based multi user detector greatly improves the system performance and mitigates the effects of MAI. However its complexity increases exponentially with increase in number of users. In this paper a Logarithmic-MAP (LOGMAP) based MUD is proposed for the MC-CDMA systems. It is shown that the proposed LOG-MAP based MUD scheme improves the BER of the system greatly and it also reduces the MAI and complexity of the system.Keywords
Logarithmic Maximum a Posteriori, Multiple Access Interference, Multicarrier Code Division Multiple Access, Multiuser Detection, Turbo Codes.Full Text
