用於多用戶下行波束成形非正交多址接入系統之使用者分群和功率分配的設計

Abstract

在本篇論文中，我們提出了用於NOMA系統的集群和分配功率的演算法，以減少干擾並提高總容量。所提出的集群演算法是根據半正交使用者選擇（SUS）演算法，其選擇具有低相關性的使用者們做為強使用者用於每個群集，因此當使用者數足夠大時，使用者之間會近似正交。而可以通過最大化SINR的性能來確定每個群集的弱使用者，通常這應該通過窮竭式搜尋法。在本篇論文中，我們發現弱使用者可以簡單地透過計算與強使用者的相關性來選擇。此外，所提出的功率分配可以最大化總容量在弱使用者擁有最小目標速率的限制下，並且我們以失效機率的方式來做性能分析。另外，我們分析了所提出的功率分配的失效機率。該分析結果表可以建議使用者的最小目標速率，使得每個集群總是可以支持兩個使用者。

In this thesis, we propose algorithms to cluster and allocate power for NOMA system to reduce interference and improve the sum capacity. The proposed clustering algorithm is based on the semi-orthogonal user selection (SUS) algorithm, which selects two users with low correlation as the strong users for two clusters and thus every pair of users is approximately orthogonal when the number of users is sufficiently large. The weak users for the two clusters can be determined by maximizing the SINR performance. Conventionally this should be done by exhaustive search. In this thesis, we find that the weak users can be selected simply via computing the correlation with the strong users. Moreover, the proposed power allocation can maximize the sum capacity under a minimum target rate constraint for the weak user and we give the performance analysis in terms of the outage probability. Furthermore, we analyze the outage probability of the proposed power allocation. This analytical result suggests the minimum target rate for the weak users so that each cluster can always support two users. Simulation results corroborate the theoretical results.