QoS-aware parallel sensing/probing architecture and adaptive cross-layer protocol design for opportunistic networks

The opening of the ultrahigh frequency (UHF) TV band by the Federal Communications Commission for opportunistic operation promises to relieve the demand on the industrial, scientific, and medical (ISM) bands. However, supporting bandwidth-intensive applications over TV white spaces can be quite challenging, due to the unpredictable nature of spectrum availability and the fluctuations in channel quality. The realization of this Herculean feat through unlicensed usage, while providing protection to licensed primary users, requires intelligent and adaptive protocol design. In this paper, we propose a quality-of-service-aware parallel sensing/probing architecture (QASPA), which exploits inherent channel and user diversity exhibited by the wireless system. Aiming at maximizing the sensing efficiency while achieving high detection accuracy, QASPA incorporates an optimal adaptive double-threshold-based sensing mechanism. It also embodies a cross-layer protocol, which uses an adaptive framing structure to minimize the control overhead, as well as a novel spectrum assignment strategy targeted at improving the spatial reuse of the network. The proposed spectrum assignment strategy supports both channel bonding and aggregation. Our simulations validate the ability of QASPA in guaranteeing the demands of high-bandwidth opportunistic flows while supporting low-bandwidth flows. They also show the superior performance of QASPA compared with the scheme used in the ECMA-392 standard for opportunistic indoor streaming.