Abstract—In this paper, a cooperative cognitive ad-hoc network is considered where a primary user and secondary users coexist with an interference user. A hybrid cooperation mechanism is proposed which allows secondary users to cooperate with primary user by forwarding the interference user’s data as well as conventionally forwarding the primary user’s data. The proposed scheme provides a more flexible approach that the secondary user can select the relay method according to channel state information. The primary user would release a reasonable portion of spectrum in return for data relay (so the primary user could improves throughput), while the secondary users could earn more spectrum access rights. When there is an interference user, secondary users could choose a method to help primary users by relay forwarding or interference mitigation depending on its own channel quality. With an aim of maximizing primary user’s rate and minimizing the secondary users’ energy consumption, a Stackelberg game framework is introduced in which a primary user is modeled as the leader and multiple secondary users are modeled as followers. The secondary users control their power to cooperate with the primary user to optimize game utilization. The existence and uniqueness of the proposed game’s equilibrium is proved and a distributed iterative algorithm is designed to reach the game equilibrium. Numerical results show that the proposed hybrid relay forwarding and interference mitigation mechanism outperforms the single cooperation scheme when an interference user exists.  
 
Index Terms—cognitive ad-hoc networks, cooperative communication, relay forwarding, interference mitigation, game theory

Cite: Shuo Li, Jun Peng, Qi Tong, Kuo-chi Lin, and Weirong Liu, "Hybrid Relay Forwarding and Interference Mitigation Mechanisms in Cooperative Cognitive Ad-Hoc Networks," Journal of Communications, vol. 8, no. 12, pp. 822-831, 2013. doi: 10.12720/jcm.8.12.822-831