On the performance of code word diversity based quasi orthogonal space time block codes in multiple-input-multiple-output systems

Abstract

In the recent past, a lot of researches have been put into designing a Multiple-Input-Multiple-Output (MIMO) system to provide multimedia services with higher quality and at higher data rate. On par with these requirements, a novel Quasi Orthogonal Space Time Block Code (QOSTBC) scheme based on code word diversity is proposed, which is a multi-dimensional approach, in this paper. The term code word diversity is coined, since the information symbols were spread across many code words in addition to traditional time and spatial spreading, without increasing transmission power and bandwidth. The receiver with perfect channel state information estimates the transmitted symbols with less probability of error, as more number of samples is available to estimate given number of symbols due to the extra diversity due to code words. The simulation results show a significant improvement in the Bit Error Rate (BER) performance of the proposed scheme when compared with the conventional schemes.

Improving the performance of free space optical systems: a space-time orthogonal frequency division modulation approach

“…, . ) is expounded into (14). The Taylor series expansion was combined with the identity expressed in (20).…”

“…The Taylor series expansion was combined with the identity expressed in (20). The limit analysis on the truncations error, the upper bound for the truncation error can therefore be expressed using (14) to (17).…”

“…And one of such turbulence-mitigation solutions is the adaptation of efficient coding schemes that have hitherto been quite successful in RF systems like transmit antenna selection multiple-input multiple-output (MIMO) systems [7], turbo coded RF system [8], superorthogonal codes for Nakagami fading channels [9], binary phase-shift keying (BPSK) trellis coded orthogonal frequency division modulation (OFDM) MIMO system [10], MIMO OFDM RF systems [11] and hybrid concatenated codes with iterative decoding RF systems [12], for FSO systems. Other similar adaptable RF error mitigating techniques include concatenated low-density parity-check (LDPC) space-time codes [13], codeword diversity technique [14], and interleaving technique for high-speed OFDM systems [15], for FSO systems as reported in space-time coded FSO system as reported in [16] and space-time coded OFDM FSO system reported in [17]. Other turbulence mitigation schemes proposed so far include the exploitation of some diversity properties to enhance the quality of communication by reducing the overall error on FSO links.…”