Survivable Load Sharing Protocols: A Simulation Study

The development of robust, survivable wireless access networks requires that the performance of network architectures and protocols be studied under normal as well as faulty conditions where consideration is given to faults occurring within the network as well as within the physical environment. User location, mobility, and usage patterns and the quality of the received radio signal are impacted by terrain, man-made structures, population distribution, and the existing transportation system. The work presented herein has two thrusts. One, we propose the use of overlapping coverage areas and dynamic load balancing as a means to increase network survivability by providing mobiles with multiple access points to the fixed infrastructure. Two, we describe our simulation approach to survivability analysis which combines empirical spatial information, network models, and fault models for more realistic analysis of real service areas. We use our simulation approach to compare the survivability of our load balancing protocols to a reference scheme within two diverse geographic regions. We view survivability as a cost-performance tradeoff using handover activity as a cost metric and blocking probabilities as performance metrics. Our results illustrate this tradeoff for the protocols studied and demonstrate the extent to which the physical environment and faults therein affect the conclusions that are drawn.