Managing TCP Connections in Dynamic Spectrum Access Based Wireless LANs

Wireless LANs have been widely deployed as edge access networks in home/office/commercial buildings, providing connection to the Internet. Therefore, performance of end-to-end connections to/from such WLANs is of great importance to network applications and end-users. The advent of Dynamic Spectrum Access (DSA) technology is expected to play a major role in improving wireless communication. With DSA enabled, WLANs opportunistically access licensed channels in order to enhance spectrum-usage efficiency, and provide better network performance. In this paper, we explore issues and solutions in realizing this potential of DSA. We first identify the key issues that impact end-to-end TCP performance when a DSA-enabled WLAN is integrated with the wired cloud. Then, we propose a new network management framework, called DSASync, to eliminate or mitigate the performance issues we identified. DSASync requires no modifications to the fixed wired network or existing network stack, while ensuring traditional TCP semantics to be obeyed. DSASync uses a combination of buffering and traffic-shaping algorithms to minimize the adverse side-effects of DSA on the TCP flows. Finally, we evaluate DSASync through a prototype implementation and deployment in a testbed. The results show significant improvements in TCP performance, e.g., a 74 increase in downlink goodput, making it a promising step forward towards applying DSA technology in consumer WLANs.