Study and Simulation of Quasi and Rotated Quasi Space Time Block Codes in MIMO systems using Dent Channel model

Multiple Input Multiple Output (MIMO) has become one of the most exciting fields in modern engineering. It is mainly used to increase data rate and capacity of wireless communication system. In this paper, we exploit the space and time diversity to decode the quasi and rotated quasi space time block codes (QOSTBC) based on dent channel model. For Doppler shifting and Rayleigh distribution we make use of dent channel model. This provides fast decoding and gives better performance of communication system.BER analysis is presented in terms of diversity and code rate. KEYWORDS: MIMO, Quasi Orthogonal Space-Time Block codes (QOSTBC), rotated QOSTBC, Maximum Likelihood (ML) decoding

Differential Distributed Space-Time Coding with Imperfect Synchronization in Frequency-Selective Channels

Differential distributed space-time coding (D-DSTC) is a cooperative transmission technique that can improve diversity in wireless relay networks in the absence of channel information. Conventionally, it is assumed that channels are flat-fading and relays are perfectly synchronized at the symbol level. However, due to the delay spread in broadband systems and the distributed nature of relay networks, these assumptions may be violated. Hence, inter-symbol interference (ISI) may appear. This paper proposes a new differential encoding and decoding process for D-DSTC systems with multiple relays over slow frequency-selective fading channels with imperfect synchronization. The proposed method overcomes the ISI caused by frequency-selectivity and is robust against synchronization errors while not requiring any channel information at the relays and destination. Moreover, the maximum possible diversity with a decoding complexity similar to that of the conventional D-DSTC is attained. Simulation results are provided to show the performance of the proposed method in various scenarios.Comment: to appear in IEEE Transaction on Wireless Communications, 201