在此研究中，我們考慮一個異質網路(heterogeneous network)，其中包含一個宏單位基地站 (macrocell) 和數個毫微單位基地站 (femtocell)。在每個毫微單位基地站中，存在接收訊號的使用者、只接收能量的潛在竊聽者、與竊取訊號的竊聽者。接收訊號的使用者，具有分配功率 (Power splitting) 之獵能 (Energy harvesting) 功能。與此同時，所有毫微單位基地台也對宏單位基地站裡的使用者造成干擾。在本篇論文我們將分為兩大部分進行探討─ 完整通道資訊 (perfect CSI) 與部分通道資訊(partial channel state information) 。在已知所有接收者的完整通道資訊下，我們致力於保密傳輸效率(secrecy rate) 的最大化，並且同時最佳化波束成型向量和功率分配參數。在只知道接收者的部分通道資訊下，我們致力於保障訊號安全性，並最大化系統效能。此共同優化涉及複雜且非凸特性的限制條件，為解決此問題，我們提出一個連續凸化近似演算法以得到高精準度的近似解。我們的模擬結果顯示此演算法在這兩個不同的通道資訊假設下均能達到傑出的效能表現。在完整通道資訊的假設中，我們的演算法比最大比率傳輸 (MRT)和沒有人工雜訊的波束成型設計相比，分別提高了420.8% 和37.3% 的效能表現。而在部分通道資訊的假設下，我們的演算法比最大比率傳輸和以沒有人工雜訊的波束成型設計相比，分別提高63% 和16% 的效能表現。這也凸顯在以安全性為主的波束成型設計於下世代的無線通訊系統中的重要性。

In this paper, we consider a heterogeneous cellular network (HCN) with a macrocell and multiple femtocells. In each femtocell, the femto base station (FBS) serves a femto user (FU), multiple potential eavesdroppers, and multiple eavesdroppers. FU is capable of simultaneous wireless information and power transfer (SWIPT) energy harvesting (EH) in a power splitting manner. All FBSs suppress their interference to macro users (MUs) via a interference power constraint. In this paper, we considered both cases of channel state information (CSI): perfect CSI and partial CSI at transmitter. For the perfect CSI case, we consider the beamforming and artificial noise design that maximize the secrecy rate. For the partial CSI case, we study the design of a resource allocation algorithm maximizing the transmission rate for the case when the legitimate receivers are able to harvest energy from radio frequency signals while ensuring signal security. The non-convex objective functions and constraints make the problem difficult to solve. To resolve this
problem, we proposed successive convex approximation (SCA) algorithms that provide high-quality approximate solutions. Simulations demonstrated that our proposed algorithm achieve
near-optimal performance for both the perfect CSI and partial
CSI cases. For perfect CSI case, our proposed algorithms improves secrecy rate by 37.3% and 420.8% over beamforming design without artificial noise scheme and MRT scheme, respectively. For partial CSI case, our proposed algorithms improves transmission rate by 63% and 16% over beamforming design without artificial noise scheme and MRT scheme, respectively. It also indicates the importance of artificial noise design in the physical layer security with SWIPT.

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