A PTAS for Delay Minimization in Establishing Wireless Conference Calls

A prevailing feature of mobile telephony systems is that the location of a mobile user may be unknown. Therefore, when the system has to establish a call between users, it may need to search, or page, to find the cells where the users currently reside, all the cells that it suspects the users may be located in. The search consumes expensive wireless links which motivates search techniques that page as few cells as possible. We consider cellular systems with n cells and m mobile users roaming among the cells. The location of the users is uncertain and is given by m probability distribution vectors. Whenever the system needs to find the users, it conducts a search operation lasting at most d rounds. In each round the system may check an arbitrary subset of cells to see which users are located there. The problem of finding a single user (that is, the case m = 1) is known to be polynomially solvable. Whereas the problem of finding any constant number of users (at least 2) in any fixe...

• Type: Conference
• Year: 2004
• Where: WAOA
• Authors: Leah Epstein, Asaf Levin
• Keywords: Constant Number, Mobile Telephony Systems, Mobile Users, WAOA 2004