Abstract
In this paper, an improved version of existing modulation schemes is investigated by inserting Hadamard codes (HC) at the peak slot of each symbol for the Visible Light Communication (VLC) system. The performance of the proposed scheme is analyzed and compared with existing schemes On-Off Keying (OOK), Pulse Position Modulation (PPM), Differential PPM (DPPM), Pulse Amplitude Modulation (PAM), Differential Amplitude PPM (DAPPM) and Differential Pulse Interval Modulation (DPIM). Moreover, the symbol error rate (SER) for kth PAM is derived for ds distances between symbols. The performance in Symbol Error Rate (SER) is improved by introducing the Positive and Negative Amplitudes (PNA) levels with respect to DC-bias. The theoretical and simulation results show that the proposed scheme outperforms the existing schemes in terms of bandwidth, and transmission capacity. Keywords: Hadamard Code Matrix, Modulation, Visible Light Communication
Highlights
Visible light communication (VLC) has been the object of extensive interest in the past few years
Consider a case, when the number of possible symbols can be represented as SPPMHC = L × Hadamard codes (HC) in Pulse Position Modulation with Hadamard Code (PPMHC); where SPPMHC shows the maximum number of symbols, L is the number of slots, and HCs is the number HC
This implies that the bits per symbol M of the scheme can be improved with L and HC, which can be defined as M ( ) = log[2] SPPMHC
Summary
Visible light communication (VLC) has been the object of extensive interest in the past few years. The choice of the modulation scheme is one of the critical factors of realizing an efficient wireless optical communication system at cost of complexity, power, error performance and bandwidth. The simulation results show approximately 2 dB transmits power reduction against classical LDPC-DAPPM without losing Bit Error Rate (BER) performance. The proposed modulation scheme achieves the trade-off between flickering and SER performance. The Grouped modulation is proposed in[13], the multiple-level PAM optical signals are utilized and enhance the data rate up to 50 Mb/s at 1e-6-bit error rate. In order to improve SER, the proposed technique does not require an additional power to increase the distance between symbols on a constellation diagram. Agha Yasir Ali, Razia Zia, Lubna Farhi, Sadia Ahmed, Umm E Laila and Muhammad Ibrar-ul-Haque
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