NOMA-Based THz Communications Under Beam Misalignment

The performance of non-orthogonal multiple access-based terahertz communications under beam misalignment is investigated. In particular, closed-form expressions are derived for the probability density function and cumulative distribution function of the signal-to-noise ratio for the near user, and the signal-to-interference-plus-noise for both the far and near users. Capitalizing on the derived statistical expressions for both users, closed-form expressions for the outage probability, average bit error rate, and average channel capacity are derived. Moreover, simple and accurate asymptotic expressions for the aforementioned performance metrics are also provided. Furthermore, an algorithm that jointly considers fair power allocation and the number of antenna array elements to maximize the sum rate is proposed. Our theoretical results are supported by Monte-Carlo simulation results, which emphasize the correctness of the analysis.