Abstract
The radio over the free space optical (RoFSO) communication system has become a popular research topic in 5G communication in recent years. Atmospheric turbulence typically degrades the performance of the RoFSO system. Multiple input multiple output, aperture averaging, error-correcting codes, and robust modulation are standard mitigation techniques used to reduce the effects of atmospheric turbulence. In this paper, Reed Solomon (RS) and Bose-Chaudhuri-Hocquenghem (BCH) coded binary shift keying (BPSK) orthogonal frequency division multiplexing (OFDM) based RoFSO system is proposed for 5G applications. We introduced RS and BCH coding techniques for the first time in this proposed RoFSO system, and achieved an average bit error rate (ABER) of \(10^{-6}\), at 40 dB, 17 dB, and 4 dB carrier to noise plus distortion ratio (CNDR) for the uncoded, RS coded, and BCH coded systems, respectively, under weak turbulence conditions. That is, when compared to the uncoded system, the proposed RS and BCH coded system provide transmit power gains of 13 dB and 34 dB, respectively. The ABER performance of the proposed coded RoFSO system is investigated and compared to an uncoded system under various turbulence, weather, and pointing error cases. In all turbulence regimes, weather conditions, and pointing error scenarios, the BCH coded system outperforms the RS coded and uncoded systems. The proposed RS and BCH coded system is energy efficient and may be useful in 5G implementation.
Highlights
One of the most important areas of research in wireless communication is radio over free space optical (RoFSO) communication
A Reed Solomon (RS) and Bose-Chaudhuri-Hocquenghem (BCH) coded binary shift keying (BPSK) orthogonal frequency division multiplexing (OFDM) based RoFSO system is proposed for 5G applications in smart cities
bit error rate (BER) of 10−7 is achieved for the enhanced misalignment of BCH coded RoFSO system with 8 dB carrier to noise plus distortion ratio (CNDR) and the same BER, for the uncoded system is achieved with 40 dB CNDR while RS coded system requires 20 dB CNDR for the same BER
Summary
One of the most important areas of research in wireless communication is radio over free space optical (RoFSO) communication. The optical beam that passes through the atmosphere comes in contact with these air masses and random fluctuations got introduced to it, this phenomenon is called the scintillation effect which degrades the system to large extent Another aggravating factor is pointing error, which occurs when the transmitter and receiver in the system are misaligned. Subcarrier intensity modulation (SIM) is employed in the FSO system, but this modulation scheme is limited by poor power efficiency [12] To overcome these shortcomings Orthogonal frequency division multiplexing (OFDM) can be used, which we have considered in this paper. We have considered the OFDM based RoFSO communication system with BPSK modulation having ECCs. We have compared the BER performance of BCH and Reed-Solomon (RS) coded RoFSO communication links with uncoded RoFSO links.
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