Soft Frequency Reuse for Underwater Acoustic Sensor Networks with Interference Mitigation and Adaptive Resources Allocation

The available bandwidth for underwater acoustic (UWA) communication and networks is very limited and frequency reuse is one of the important techniques to improve spectrum efficiency and system capacity. In this paper, a soft frequency reuse (SFR) system is proposed for UWA multi-cell networks, with the consideration of channel features in two aspects, one is inter-cell interference mitigation, another is inner-cell resources allocation. For inter-cell, the propagation speed of UWA signal is very slow, resulting in that signals will arrive at receiver with difference delays, herein a new idea to mitigate the inter-cell interference based on propagation delay differences has been proposed. For inner-cell, resources allocation for multiple nodes can be performed according to the feedback channel state information (CSI). Dealing with the effect of time-varying UWA channel on the feedback CSI, a linear finite state Markov chain (LFSMC) predictor is proposed to obtain more accurate CSI for adaptive allocation. The allocation objective is to maximum network throughput. The simulation results have shown that, the proposed delay aware SFR performs higher signal to interference plus noise ratio (SINR) and spectrum efficiency in comparison to traditional SFR and FFR, and adaptive resources allocation with LFSMC predicted CSI has higher throughput. Finally, with the proposed scheme, UWA sensor networks can achieve better throughput performance in comparison to FFR and SFR without propagation delay and resources allocation consideration.