QoS-oriented distributed opportunistic scheduling for wireless networks with hybrid links

In this paper opportunistic scheduling is studied for a wireless network with hybrid links that have different characteristics and quality of service (QoS) requirements. More specifically, we consider two types of links coexisting in a network: 1) secure links for critical messages demanding physical layer security; 2) regular links for other messages. Since the transmission rate of a secure link is usually much lower than that of a regular link, fair sharing of the transmission opportunity between two types of links has some drawbacks: 1) if secure links generate more packets, the network throughput is low; 2) if regular links generate more packets, QoS of secure links may not be satisfied. To effectively schedule transmissions in a network with hybrid links, a QoS-oriented distributed opportunistic scheduling scheme is developed to maximize the overall system throughput under the constrains of QoS requirements of secure links. It is derived based on the optimal stopping theory. Performance results show that QoS of secure links can be gracefully guaranteed without necessarily compromising the overall throughput of hybrid links.