Performance analysis of downlink multipath multi-user NOMA-VLC system

Abstract

In the present paper, the performance of non-orthogonal multiple access (NOMA) in a downlink multipath multi-user Visible Light Communication (VLC) system has been evaluated w.r.t bit-error rate (BER), sum rate & outage probability. The results show that the sum rate and BER performance improve with the increase in semi-angle 𝝋 𝟏 𝟐 ⁄ of the LED using both Line-of-sight (LOS) and LOS plus first reflection (L-R1) signals. The simulation results display that there is optimal value of 𝝋 𝟏 𝟐⁄ at which minimum BER is achieved. However, the optimal angle of semi-angle varies with the number of users and order of reflection of signal. In case of two-user system with LOS signal, the optimal angle is 𝟓𝟎 𝟎 and 𝟕𝟎 𝟎 for user-1 & user-2 respectively, whereas, for three-user system the optimal angle is 𝟑𝟎 𝟎 for user-1 and it is 𝟓𝟎 𝟎 for each user-2 and user-3. The BER simulation results for L-R1 signal reveal that the successive interference cancellation (SIC) efficiently decodes the signal for two-user system with optimum performance at 𝝋 𝟏 𝟐 ⁄ equals to 𝟕𝟎 𝟎 but as the number of users increases to three, it fails to decode the signal. The results of sum rate vs. offset using LOS signal show that sum rate for two-user system monotonically increases & then decreases with the increase in semi-angle. The optimal angle is 𝟓𝟎 𝟎 for the maximum sum rate which also supports the BER results. The effect of shadowing (blocked LOS signal) shows that the sum rate is zero for lower values of semi-angle of LED. Finally, the outage probability against target rate of far user confirms the key finding results of shadowing.

Enhanced Gain Difference Power Allocation for NOMA-Based Visible Light Communications

“…Closed-form expressions for the bit error rate (BER) of NOMA-VLC systems with on-off keying (OOK) and L-ary pulse position modulation have been derived, considering perfect and imperfect channel state information [14]. The results of [15] demonstrated that the performance metrics (BER, sum rate, and outage probability) in a multi-user NOMA-VLC system can be affected by the number of users, signal type, and shadowing under different half-angles of LEDs and signal reflection path conditions.…”

BER-performance evaluation for 5G-PD-NOMA system in multipath communication channels

“…Mahmood et al [15], Hassan et al [23], and Kumar et al [25] a power domain NOMA system is tested. The BER performance is evaluated on Stanford University Interim (SUI) fading channel models considering a various number of users per-cluster in suburban environments.…”