Artificial-Noise-Aided Transmit Optimization for Service Integration in MIMO-OFDM Systems

摘要

This paper considers a new frequency-domain artificial noise (AN)-aided transmit design for service integration in a multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system. In this system, two sorts of service messages are combined and provided simultaneously at each frequency subchannel: one multicast message intended for all receivers and one confidential message intended for only one receiver. The confidential message is kept perfectly secure from all the other receivers. To characterize the tradeoff between the secrecy rate and multicast rate, our goal is to maximize the weighted sum of the two rates over all subchannels by jointly designing the input covariances for the multicast message, confidential message and AN at each subcarrier. This problem is nonconvex by nature and challenging to solve. To make it tractable, we recast this weighted sum rate maximization (WSRM) problem into a primal decomposable form, which is amenable to alternating optimization (AO). By this means, we can obtain a locally optimal solution to the WSRM problem. Numerical results are finally presented to show the efficacy of our proposed method and reveal some insights into our considered scheme.