QoS Provisioning in Multihop Outdoor Public Access Networks with Asymmetric User Traffic

With the goal to provide ubiquitous wireless Internet access, large-scale deployment of outdoor public access networks will continue at a rapid pace in the next years. In outdoor environment, connecting access points (APs) via cables is costly and requires a lot of cabling engineering work. Therefore, the multihop-augmented network architecture has become an option of upsurging interest. This paper investigates how to deploy APs in an outdoor public access network to improve throughput and quality-of-service (QoS) while extending the coverage by multihop communications. Frequency planning is suggested to improve user throughput with QoS provisioning, and to make the multihop network more scalable to facilitate coverage extension. To investigate the overall tradeoffs among QoS, throughput, and coverage, we develop an analytical throughput and delay model for this multihop network using the carrier sense multiple access (CSMA) medium access control (MAC) protocol. This model also considers bidirectional asymmetric traffic for users operating in the unsaturated situation. Then, we apply an optimization approach to determine the optimal number of APs in a cluster and the best separation distances between APs, aiming to maximize the capacity and coverage of a cluster of APs subject to the delay requirement.