Abstract
In this paper, a full-duplex (FD) transmitter cooperative scheme is proposed to improve the achievable rate for multiple access channels (MACs). In the proposed scheme, by leveraging the FD amplify-and-forward (AF) protocol, two FD transmitters send their own signals and forward the received signals from their counterparts to the receiver, which adopts both the forward and backward decoding schemes to decode the source messages. First, the analyses of the equivalent channel model and the statistics of the accumulated additive white Gaussian noise and residual self-interference (ANRI) caused by imperfect self-interference cancellation are performed. Then, the achievable rate regions are obtained by utilizing both the forward and backward decoding schemes, and a two-stage iterative algorithm is proposed to characterize these regions: in each iteration, the covariance matrix of the ANRI is first updated; then, for the fixed covariance matrix of the ANRI, the transmission parameters of the two transmitters are calculated by a two-step iterative algorithm based on the parametric Dinkelbach algorithm, sequential convex programming (SCP), and semidefinite relaxation (SDR). The numerical results show that the proposed scheme outperforms the half-duplex cooperative scheme and conventional MAC scheme without cooperations when the channels between the two transmitters are in good condition.
Highlights
By treating cooperative transmitters as a virtual antenna array, cooperative communication has attracted extensive attention as it can potentially improve network throughput and reliability
There are various cooperative schemes that are being studied under different channel models, such as relay channels [1], [2] and cooperative multiple access channels (CMAC) [3]–[12]
As a promising application of CMAC in cellular networks, mobile users can cooperatively send messages to the base station, which results in a larger achievable rate region and lower outage probability [7]
Summary
By treating cooperative transmitters as a virtual antenna array, cooperative communication has attracted extensive attention as it can potentially improve network throughput and reliability. The transmitter cooperation is based on in-band FD communications: the two transmitters synchronously transmit and receive signals at the same frequency band; conferencing and transmitter–receiver links use the same frequency band Under this setup, because analog signal processing in the AF transmitters is much simpler than that in DF, the transmitters adopt the AF protocol in this work. 2) We obtain the achievable rate regions of the proposed cooperation scheme for CMAC by solving two nonconvex optimization problems using a two-stage iteration algorithm: First, update the covariance matrix of the ANRI, and the transmission parameters for the VOLUME 7, 2019 two transmitters are calculated by a two-step iterative algorithm based on the parametric Dinkelbach algorithm, sequential convex programming (SCP), and semidefinite relaxation (SDR) for the fixed covariance matrix of the ANRI.
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