非理想信道狀態(tài)信息的認(rèn)知無線網(wǎng)絡(luò)下行功率分配和波束賦形方法
doi: 10.11999/JEIT171135
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國家數(shù)字交換系統(tǒng)工程技術(shù)研究中心 ??鄭州 ??450002
基金項(xiàng)目: 國家863計劃(SS2015AA011306),國家自然科學(xué)基金(61379006, 61521003)
Cognitive Radio Network Downlink Power Allocation and Beamforming Method with Imperfect Channel State Information
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National Digital Switching Systems Engineering & Technological Research Center, Zhengzhou 450002, China
Funds: The National 863 Program of China (SS2015AA011306), The National Natural Science Foundation of China (61379006, 61521003)
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摘要: 針對非理想信道狀態(tài)信息(CSI)條件下工作于underlay模式的認(rèn)知無線網(wǎng)絡(luò)(CRN)多用戶下行功率分配和波束賦形研究中普遍存在的問題,包括忽略主網(wǎng)絡(luò)(PN)對認(rèn)知用戶(SU)的干擾、傳統(tǒng)的凸優(yōu)化SDR方法對約束條件的近似要求以及實(shí)現(xiàn)算法復(fù)雜、實(shí)用性受限等,首先建立CRN模型,增添PN對SU的干擾項(xiàng),而后在非理想CSI的最差條件下形成優(yōu)化問題。再通過Lagrange對偶對問題的約束條件進(jìn)行變換,并基于變換后的問題形式,利用上行和下行的對偶特性,引入虛擬功率,將優(yōu)化問題轉(zhuǎn)換為上行功率分配和波束賦形問題,進(jìn)一步得到簡便、快速和實(shí)用的迭代算法。數(shù)值仿真顯示,算法收斂很快。并且發(fā)現(xiàn)非理想CSI引起的誤差不僅對下行功率影響明顯而且還改變優(yōu)化問題的可行解區(qū)域;PN基站(PBS)的發(fā)送功率的變化對可行解區(qū)域有顯著的影響。
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關(guān)鍵詞:
- 認(rèn)知無線網(wǎng)絡(luò) /
- 非理想信道狀態(tài)信息 /
- 迭代算法 /
- 可行解區(qū)域
Abstract: Some problems of multi-user downlink power allocation and beamforming in a underlay Cognitive Radio Network (CRN) with imperfect Channel State Information (CSI) are addressed. They include ignoring the interferences of the Primary Network (PN) to the Secondary Users (SU), conventional SDR algorithm of convex optimization needing the constraint approximation, the high complexity of the algorithm, and implemented with difficulty, etc. Firstly the term of interference of the PN to the SU is added to the CRN model. The optimization problem is formulated with the worst-case imperfect CSI. Next the constraints of the problem are transformed by means of Lagrange duality. Then, based on the form of the problem, the simple, fast and practical iterative algorithm is obtained by utilizing the duality of uplink-downlink, introducing virtual power, and transforming the optimization problem into the problem of uplink power allocation and beamforming. Numerical simulation results show that it converges faster. It is also found that the errors of the imperfect CSI not only influence the downlink power but also change the feasibility region. The variation of transmitting power of the PN Base Station (PBS) could affect the feasibility region notably. -
表 1 不同收斂門限下的迭代次數(shù)
序號 1 2 3 4 5 收斂門限 $\delta $ 10–3 10–4 10–5 10–6 10–7 迭代次數(shù) $N$ 11 17 25 47 67 下載: 導(dǎo)出CSV
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