Performance Enhancement for Wireless Networks: Modulation, Clock Synchronization and Resource Management

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dc.contributor.author Yang, Zhe
dc.date.accessioned 2013-05-08T20:08:51Z
dc.date.available 2013-05-08T20:08:51Z
dc.date.copyright 2013 en_US
dc.date.issued 2013-05-08
dc.identifier.uri http://hdl.handle.net/1828/4603
dc.description.abstract Wireless networks become more and more important in modern information systems as the last mile/meter solutions, thanks to the flexibility of mobile access to facilitate Internet access anytime, anywhere. Given the limited resources, e.g., spectrum and energy supplies, to meet the ever increasing demand for wireless data services, new approaches are beckoned to enhance the spectrum and energy efficiency. We investigate this problem from three important aspects, digital modulation, clock synchronization and concurrent transmission scheduling. The contributions of this dissertation are four-fold. First, we employ the cross-layer design to explore the spatial diversity and broadcast nature of wireless links and propose a novel network modulation scheme that can superpose the information bits of different priorities into one symbol. It offers a new dimension to improve the network throughput since we can flexibly configure the transmission according to the channels among transceivers. Moreover, it is compatible with the main-stream hardware and we just need a software upgrade to implement the idea. Second, we propose modulation schemes based on hexagonal tiling, which is known to be the most compact way of two-dimensional regular tiling. In order to fully utilize the advantage of hexagonal constellation, we employ the non-binary error controlcoding since the number of constellation points of hexagonal constellation is not necessarily to be an integer power-of-two. The feasibility of these new modulation schemes is verified by the prototype system based on the software defined radio platform USRP2 and GNU Radio. Third, to facilitate a wide range of wireless communications technologies and protocols, clock synchronization among several wireless devices is a fundamental requirement. We investigated this problem by tracing to the source of clock desynchronization, which is the clock skew. However, as shown by measurement results, the clock skew is not constant and related to the working temperature. We propose a novel clock skew estimation algorithm that can leverage the temperature information to accurately estimate the clock skew. Based on the estimation results, we propose a clock synchronization scheme that can directly remove the clock skew according to the working temperature. Fourth, the traditional time-sharing based scheduling schemes usually schedule one transmission within certain area. The emerging broadband wireless devices can dynamically adjust the transmitted data rate according to the received signal to interference and noise ratio (SINR). Allowing concurrent transmissions may be more efficient, while optimal scheduling problem for concurrent transmissions is an NP-hard problem. We propose simple yet effective heuristic algorithms that can significantly improve the system throughput with moderate computational complexity. en_US
dc.language English eng
dc.language.iso en en_US
dc.subject wireless network en_US
dc.subject network modulation en_US
dc.subject hexagon modulation en_US
dc.subject clock synchronization en_US
dc.subject clock skew en_US
dc.subject concurrent transmission en_US
dc.subject scheduling en_US
dc.title Performance Enhancement for Wireless Networks: Modulation, Clock Synchronization and Resource Management en_US
dc.type Thesis en_US
dc.contributor.supervisor Cai, Lin
dc.degree.department Dept. of Electrical and Computer Engineering en_US
dc.degree.level Doctor of Philosophy Ph.D. en_US
dc.rights.temp Available to the World Wide Web en_US
dc.identifier.bibliographicCitation [1]  Z. Yang, L. Cai, Y. Luo, and J. Pan, “Topology-aware modulation and error-correction coding for cooperative networks,” IEEE JSAC, vol. 30, no. 2, pp. 379-387, Feb. 2012. en_US
dc.identifier.bibliographicCitation [2] Z. Yang, L. Cai, Y. Liu, and J. Pan, “Environment-Aware Clock Skew Estimation and Synchronization for Wireless Sensor Networks,” IEEE Infocom, Orlando, FL, USA, March 2012. en_US
dc.identifier.bibliographicCitation [3] Z. Yang, Y. Luo, and L. Cai, “Network Modulation: A New Dimension to Enhance Wireless Network Performance," IEEE Infocom'11, Shanghai, China, May 2011.  en_US
dc.identifier.bibliographicCitation [4] Z. Yang, L. Cai and W. Lu, "Practical Concurrent Transmission Scheduling Algorithms for Rate-adaptive Wireless Networks," IEEE Infocom'10, Mar. 2010, San Diego, CA, USA. en_US
dc.identifier.bibliographicCitation [5] Z. Yang, J. Pan and L. Cai, "Adaptive clock skew estimation with Interactive Multi Model Kalman filter for sensor networks," IEEE ICC'10, May 2010, Cape Town, South Africa. en_US
dc.description.scholarlevel Graduate en_US
dc.description.proquestcode 0544 en_US

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