Energy-Efficient Power Allocation for Multi-user Single-DF-Relay Networks
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In wireless relay networks, energy efficiency not only affects the lifetime of mobile terminals, but also is a promising way to realize high-rate green communication by reducing transmission power and decreasing mutual interference. In this paper, for multi-user single-DF-relay cooperative networks, where the transmission power of all nodes are constrained and the direct links between sources and destinations are considered, the problem of optimal power allocation is formulated as how to solve a Lagrangian Function. Though it is difficult to get solution with Karush–Kuhn–Tucker (KKT) conditions directly, the solution of the Lagrangian Function is classified into two categories based on the analysis of Lagrangian Multipliers. Then, exact optimal power allocation strategies to minimize system-sum-power consumption are presented for both categories respectively. With the proposed scheme, not only all power constraints are satisfied, but also pre-determined target SNRs can be reached. Further numerical simulations are carried out to show the performance of the proposed strategies.
KeywordsSystem-sum-power consumption Cooperative communication Multi-user single-relay Decode-and-forward(DF) Karush–Kuhn–Tucker(KKT)
This work was supported by the Open Project Program of the Key Laboratory of Universal Wireless Communications (2016-KFKT-2016104), Ministry of Education, the Beijing University of Posts and Telecommunications, and the Natural Science Foundation of Hunan Province of China (2017JJ2249). And it was also funded by China Scholarship Council.
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