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Use Of Unitary Differential Space Time Frequency Codes For MB-OFDM UWB Transceiver

Karavalla Hemanth Reddy, F.Renisha

In recent day’s military and government applications of UWB communications have demanded the accommodation of larger numbers of users, each with ever increasing bandwidth requirements. Spectral resources are potentially wasted in order to avoid narrowband interference in the case single carrier based multi band system. For channel state information channel estimation requires large number of pilot symbols need to be transmitted, thus reducing the bandwidth efficiency and it will also lead complexity in the receiver side. This paper proposes unitary differential space-time-frequency codes (DSTFCs) for MB-OFDM UWB communications, which increase the system bandwidth efficiency because no channel state information (CSI) is required. The proposed system would be useful when CSI is unavailable at the receiver. The paper also quantifies for the variable puncture rate Forward error correction scheme for significant improvement in the bit error performance of proposed MB-OFDM. Performance of proposed system is analyzed in deep fading environment (Nagakami-m channel) results are presented which show that the variable rate forward error correction (FEC) with MBOFDM UWB communication is better than that with conventional system, and the BER performance is also be improved significantly .