<p> The explosive mobile data growth needs more spectrum to accommodate the traffic. Existing policy of exclusive spectrum access has made today's spectrum both over-controlled and underutilized. One possibility to improve spectrum efficiency is via dynamic spectrum sharing, which has the potential to release a large percentage of underutilized spectrum. </p><p> Cognitive radio is one of the most promising technologies to facilitate dynamic spectrum sharing. Yet, there exist many problems for cognitive radio to support multimedia communications. This dissertation advances the concept of <i>“spectrum aware”</i> for cognitive-radio based wireless multimedia communication system. We interpret spectrum awareness in a broad way which includes spectrum sensing, spectrum effectiveness and spectrum efficiency. In particular, we have made the following contributions in this dissertaion: </p><p> • We design and implement RECOG, a cognitive radio (CR) system that improves conventional CR with a smart sensing, fast backup channel searching and QoS managing. The proposed system is the first fully-fledge CR system that can supports real-time applications such as video chat. </p><p> • We design and implement PINOKIO, a system that monitors spectrum usage and improves spectrum efficiency in frequency-agile WiFi networks. </p><p> • We design and implement FAVICS, a frequency-aware video communication system that leverages the nature of unequal error protection (UEP) in frequency diversity for wireless streaming without modifying existing wireless PHY, and improve the peak signal-to-noise ratio (PSNR) of video streaming by 5∼10 dB.</p>
| Identifer | oai:union.ndltd.org:PROQUEST/oai:pqdtoai.proquest.com:3596957 |
| Date | 21 November 2013 |
| Creators | Tan, Kefeng |
| Publisher | University of California, Davis |
| Source Sets | ProQuest.com |
| Language | English |
| Detected Language | English |
| Type | thesis |
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