In order to mitigate the error propagation (EP) effect on the bit error rate (BER) performance due to the imperfect successive interference cancellation for the non-orthogonal multiple access (NOMA)-based visible light communication (VLC) downlinks, adjustable bit rate superposition coding (ABRSC) and sample-and-sum successive interference cancellation (SSSIC) decoding schemes are proposed in this paper. Based on the modified fixed-power allocation (MFPA) strategy, the closed-form expressions of BER are derived for the two-user case with on-off keying, and further extended to the multi-user scenario. The residual probability of EP is introduced and derived to theoretically assess the effectiveness of the proposed ABRSC and SSSIC schemes. Monte Carlo simulation is also conducted to validate the analytical BER results. The BER performance of the NOMA-based VLC system with multiple users is further analyzed and discussed in detail. It is found that under the total average optical transmission power constraint, the allocated average optical transmission power to current user should be higher than that to all rest of users, i.e., the power allocation factor (PAF) is supposed to be greater than 1/2, in order to avoid the error floor issue of current user, hence facilitating the successful implementation of SSSIC. Besides, increasing the bit-rate factor (BRF) could mitigate the effect of EP, and larger BRF leads to more efficient outcomes in alleviating the effect of EP.

中文翻译：

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可见光通信中采用误差传播缓解方法的下行非正交多址误码性能分析

为了减轻基于非正交多址 (NOMA) 的可见光通信 (VLC) 下行链路的不完善的连续干扰消除对误码率 (BER) 性能的错误传播 (EP) 影响，可调比特率本文提出了叠加编码（ABRSC）和采样求和连续干扰消除（SSSIC）解码方案。基于修正的固定功率分配（MFPA）策略，推导出了具有开关键控的双用户情况下BER的闭式表达式，并进一步扩展到多用户场景。引入并推导出EP的残差概率，以从理论上评估所提出的ABRSC和SSSIC方案的有效性。还进行了蒙特卡罗模拟以验证分析 BER 结果。进一步详细分析和讨论了基于 NOMA 的多用户 VLC 系统的误码率性能。发现在总平均光传输功率约束下，分配给当前用户的平均光传输功率应该高于其他所有用户，即功率分配因子（PAF）应该大于1/ 2、为了避免当前用户的error floor问题，从而有利于SSSIC的成功实施。此外，增加比特率因子（BRF）可以减轻EP的影响，更大的BRF在减轻EP的影响方面会产生更有效的结果。分配给当前用户的平均光传输功率应该高于其他所有用户的平均光传输功率，即功率分配因子（PAF）应该大于1/2，以避免当前用户的error floor问题，从而促进 SSSIC 的成功实施。此外，增加比特率因子（BRF）可以减轻EP的影响，更大的BRF在减轻EP的影响方面会产生更有效的结果。分配给当前用户的平均光传输功率应该高于其他所有用户的平均光传输功率，即功率分配因子（PAF）应该大于1/2，以避免当前用户的error floor问题，从而促进 SSSIC 的成功实施。此外，增加比特率因子（BRF）可以减轻EP的影响，更大的BRF在减轻EP的影响方面会产生更有效的结果。