Continuous Spatial Query Processing in Mobile Information Systems

Nowadays, many mobile applications provide location-based services that allow users to access location-related information from anywhere, whenever they desire. A moving user can issue queries to access information about moving or static objects. Continuous spatial query processing systems are used for this type of application. We propose two query processing strategies for location based services. The objectives of our strategies are to reduce: (1) the server workload, (2) the data transmission cost and (3) the query response time, for location-based services while providing an answer for a continuous region query. We compare our first strategy with a brute-force strategy and found that our strategy can significantly reduce the server workload and data transmission cost over the brute-force method. We compare our improved strategy with the original strategy and brute-force strategy. The experimental results show that the improved strategy achieves lower query response time than the original and brute-force strategy

TCP Performance Over Mobile IP Wired-cum-Wireless Networks

Reliable transport protocol like TCP has served well the wired Internet where the packet losses are mainly due to congestion but is not ready for Mobile IP wired-cum-wireless environments where the significant packet losses are due to bit errors and handoffs In this paper we have investigated the performance of TCP among the various TCP variants We have observed both TCP senders Newreno Vegas and TCP receivers Base Delayed-Ack Using ns-2 we have evaluated the TCP throughput and packet delay over a single TCP connection The simulation results suggest that a particular combination one TCP sender with one TCP receiver of TCP shows the best result in such Mobile IP network