Optimal Power Allocation in an Amplify-and-Forward Untrusted Relay Network with Imperfect Channel State Information
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The characteristics of the wireless medium create difficulty to shield the data transmission from unauthorized recipients. In this paper, power optimization in an amplify-and-forward untrusted relay network is presented, using cooperative jamming transmission to prevent the untrusted relay from intercepting the confidential signals. Considering imperfect channel estimation error at the destination, an optimal power allocation (OPA) is designed to maximize the achievable secrecy rate for the network. Simplified OPA is derived for high signal-to-noise ratio regime with imperfect CSI and the ergodic secrecy rate is also analyzed to evaluate the achievable average secrecy rate for different scenarios as a common performance metric. The numerical results show that when the error of CSI is considered, the proposed OPA generates limited and acceptable degradation on the secrecy rate.
KeywordsCooperative jamming Optimal power allocation Untrusted relay network Imperfect CSI Ergodic secrecy rate
This work was supported in part by the National Natural Science Foundation of China (Nos. 61501376 and 61701407), the Fundamental Research Funds for the Central Universities (Nos. 3102016ZY020 and 3102017JG02002) and the Graduate Starting Seed Fund of Northwestern Polytechnical University (No. ZZ2017128).
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