WSEAS CONFERENCES. WSEAS, Unifying the Science

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Oct. 2007, Nov. 2007, Dec. 2007, 2008


Issue 12, Volume 6, December 2007
Print ISSN: 1109-2742
E-ISSN: 2224-2864








Title of the Paper:  Capacity and Performance Analysis of Space-Time Block Codes in Rayleigh Fading Channels


Authors: A. S. Hiwale, Dr. A. A. Ghatol

Abstract: Multi-Antenna systems are expected to play very important role in future multimedia wireless communication systems. Such systems are predicted to provide tremendous improvement in spectrum utilization. In this paper we consider the capacity analysis of Multiple-Input Multiple-Output (MIMO) systems. Space-Time coding schemes are the practical signal design techniques to realize the information theoretic capacity limits of MIMO systems. Here the orthogonal space-time block codes are considered for the capacity and error probability analysis of MIMO systems as a case study. The numerical and simulation results obtained using MATLAB are presented for the Multi-antenna system channel capacity and bit-error probability in Rayleigh fading channels.

Keywords: space-time codes, transmit diversity, Rayleigh fading channels, Channel capacity, MIMO.

Title of the Paper: An Improved SIC based Turbo Equalizer


Authors: Aruna Tripathy, Sant Saran Pathak, Saswat Chakraba

Abstract: This paper investigates a new soft interference canceller (SIC) based turbo equalizer. The SIC is configured as a decision feedback (DF) equalizer that uses two linear transversal filters. Both the filters update their taps as per the least mean square (LMS) algorithm. This receiver is different from the receivers discussed in literature in the sense that it uses the soft outputs of both the equalizer and the decoder in order to provide an improved estimate of the post cursors. It also uses the variance of the soft data bit estimates in its computation of the log-likelihood ratios (LLR). Probability distribution function for the soft data bit estimate is derived. This SIC based turbo equalizer is shown to result in a faster convergence and improved error floor at the decoder output. This study is carried out for a two typical highly frequency selective channels in order to establish the better performance of the proposed receiver.

Keywords: SIC, LLR, SCS, LMS, Soft Output

Title of the Paper: Performance Improvement of Synchronous Multiuser Communication Systems by Using Process Sharing Techniques


Authors: Mohd Fadzil Ain, Farid Ghani, Mutamed Khatib, Syed Idris Syed Hassan

Abstract: This paper presents new techniques that improve the performance of Code Division Multiple Access (CDMA) system for transmission of digital data over time varying channels such as high frequency mobile channels. The main ideas presented here are to share the equalization process between the transmitter and the receiver of the system with a certain ratio that maximize the signal to noise ratio (SNR). The channel characteristics should be known at the transmitter and receiver, it is the requirement for all systems that employ coding at the transmitter.

Keywords: Signal processing, communications, sharing, coding, CDMA.

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