Optimal resource allocation and cross-layer control in cognitive and cooperative wireless networks

Abstract

We investigate four problems on optimal resource allocation and cross-layer control in cognitive and cooperative wireless networks with time-varying channels. The first three problems consider different models and capabilities associated with cognition and cooperation in such networks. Specifically, the first problem focuses on the dynamic spectrum access model for cognitive radio networks and assumes no cooperation between the licensed (or "primary") and unlicensed (or "secondary") users. Here, the secondary users try to avoid interfering with the primary users while seeking transmission opportunities on vacant primary channels in frequency, time, or space. The second problem considers a relay-based fully cooperative wireless network. Here, cooperative communication techniques at the physical layer are used to improve the reliability and energy cost of data transmissions. The third problem considers a cooperative cognitive radio network where the secondary users can cooperatively transmit with the primary users to improve the latter's effective transmission rate. In return, the secondary users get more opportunities for transmitting their own data when the primary users are idle.