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| Multiplexing Analysis for Dynamic Spectrum Allocation | |||
| Chandra,Kavitha | University of Massachusetts Lowell | ||
| Keshavamurthy,Sushma | University of Massachusetts Lowell | ||
| This work presents a cross-layer analysis of the problem of dynamic sensing and acquisition of open RF spectrum by secondary subscribers. The joint requirements at the medium access and physical layers of the wireless system are investigated using a queueing model of the carrier-sense multiple access and collision avoidance (CSMA/CA) protocol. The performance of the protocol is analyzed considering multiple channels in contention and with each channel subject to time-varying capacity constraints as determined by the physical layer. The focus is on the derivation of parameters of secondary access time distributions that can be optimally multiplexed with primary usage patterns. In this context we assume Poisson distributions for the legacy users and evaluate the impact of secondary sources accessing the spectrum with exponential, hyper-exponential and Pareto distributed inter-access times. The admission of secondary sources characterized by high variability in the inter-access times is shown to improve the spectrum utilization while minimizing the performance impact on primary users. The impact of intermittent and bursty temporal access patterns on the stability of the CSMA/CA protocol will also be addressed. | |||
| Kavitha Chandra is a professor in the department of electrical and computer engineering at University of Massachusetts Lowell since 1996. Prior to this she was a member of technical staff in the Teletraffic and System Performance department of AT&T Bell labs in Holmdel, NJ. Her research group addresses problems in performance modeling of communications systems and networks. Prof. Chandra is a recipient of the NSF Career Award in 1998 and the Etta Kappa Nu Outstanding Young Electrical Engineer award with honarable mention in 1996. | |||