結合基於波束成型選擇方法以及粒子最佳化演算法之 空間編碼於大規模多輸入多輸出系統

Beamforming-selection Precoding with Particle Swarm Optimization in Massive MIMO Systems

李景硯(Jing-Yen Lee)

指導教授 ： 李枝宏

國立臺灣大學/電機資訊學院/電信工程學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201600828

摘要

之前的學者提出了beamforming-selection precoding (BSP)方法以降低frequency-division duplex (FDD) 大規模多輸入多輸出(massive multiple-inputmultiple-output ,massive MIMO)之downlink training以及channel state information(CSI) 回傳的負擔，然而BSP方法有一個缺陷，他們使用了一組他們自行定義的固定beamformnig系數作為BSP方法的precoder，這會造成使用者(UEs)之間的干擾問題，因此這篇論文提出了一種方法修正BSP，我們運用了粒子最佳化演算法(PSO)去搜尋最佳的beamformnig系數運用於BSP，如此便可以大幅地降低使用者間的干擾，我們稱我們提出的方法為BSP-PSO，BSP-PSO比起原本的BSP不僅可以達到更好的位元錯誤率(BER)，也保留了原本BSP擁有較低的downlink training 以及 CSI回傳的負擔的優點。此外，我們提出了一種新的基於平均錯誤率公式的PSO適應值方程式，數個模擬結果顯示了在各種通道環境中或考慮mutual coupling情況下，我們的BSP-PSO方法在位元錯誤率(BER)效能下比原來的BSP方法有著非常大的改進。

關鍵字

大規模輸入與輸出 ； 空間編碼 ； 通道資訊(CSI) ； 波束成型 ； 分頻雙工(FDD) ； 合作式粒子演算法(CCPSO) ； 位元錯誤率(BER)

並列摘要

The beamforming-selection precoding (BSP) has been used by researchers to reduce overheads of the downlink training and the channel state information feedback in the frequency-division duplex (FDD) massive multiple-inputmultiple-output (MIMO) systems. However, the BSP has a weakness that using a set of pre-defined fixed beamforming coefficients can cause the interference problem between user equipments (UEs). Thus, this paper proposes a method that incorporates the BSP with a cooperatively coevolving particle swarm optimization(PSO) algorithm such that the designed beamforming coefficients can greatly reduce the severe interference between UEs. This proposed method, termed the BSP-PSO method, not only can achieve better bit error rate (BER) performance than the original BSP, but also preserves advantages of the BSP having lower overheads of the downlink training and the CSI feedback. Additionally, we propose a new fitness function for this cooperatively coevolving PSO based on the derived average BER formula. Numerical simulations are also demonstrated for both the urban-macro and the urban-micro wireless scenarios to validate the superior BER performance of the proposed precoding method.

並列關鍵字

multiple input multiple output(MIMO) ； spatial precoding ； limited channel state information (CSI) ； beamforming ； frequency-division duplex (FDD) ； cooperatively coevolving particle swarm optimization(CCPSO) ； bit error rate (BER)

參考文獻

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