Spectrum Sharing between Cooperative Relay and Ad-hoc Networks: Dynamic Spectrum Access, Resource Allocation and Real-time Implementation

Yin Sun, Xiaofeng Zhong, Tsung-Hui Chang, Shidong Zhou, Jing Wang, and Chong-Yung Chi Abstract This paper studies the spectrum sharing problem between a cooperative relay network (CRN) and a nearby ad-hoc network that operates over the same spectral band. In the uplink CRN transmission, both the source node and relay node can interfere with the ad-hoc links. By virtue of that the CRN can predict the ad-hoc traffic through spectrum sensing, we optimize the spectrum access and resource allocation strategy of the CRN such that the average traffic collision time between the two networks can be minimized while maintaining a required uplink throughput for the CRN. The associated design formulation turns out to be a non-convex optimization problem. By analyzing the optimal spectrum access strategy, we show that this spectrum sharing problem can be reformulated as a convex problem and solved by a low-complexity Lagrangian optimization method. The development is first for a framelevel resource allocation strategy, and then is further extended to an ergodic resource allocation strategy that considers long term average CRN throughput and long term average traffic collision time. For the ergodic strategy, an efficient, practical real-time implementation method is also presented. Simulation results are presented to demonstrate the efficiency of the proposed spectrum sharing strategies. Index terms− Cognitive radio, relay network, ad-hoc network, resource allocation, spectrum access, spectrum sharing, interference prediction. EDICS: WIN-CONT, WIN-RSMG, SPC-MULT, SPC-CRDS