| In wireless mobile communication system, radio spectrum is a limited resource. However, efficient use of available channels has been shown to improve the system capacity. The role of a channel assignment scheme is to allocate channels to cells or mobiles in such a way as to minimize call blocking or call dropping probabilities, and also to maximize the quality of service. Channel assignment is known to be an NP-hard optimization problem. In this thesis, we have developed an Evolutionary Strategy (ES) which optimizes the channel assignment. The proposed ES approach uses an efficient problem representation as well as an appropriate fitness function. Our thesis deals with a novel hybrid channel assignment based scheme called D-ring. Our D-ring method yields a faster running time and simpler objective function. We also propose a novel way of generating initial candidate solutions that are near optimal. We have obtained at least better results (as well as faster running time) than a similar approach in literature.; The efficient use of available channels and transmitter power have been shown to improve the system capacity. The role of power control is to assign power level to each transmitter so that the signal quality is maintained and interference is minimized. Existing papers have focused on optimizing the assignment of channels assuming that the allocation of transmitter power is known and fixed (vice-versa). In this thesis, we integrate the problem of channel assignment with power control using the dynamic reuse distance concept. Using an efficient problem representation as well as an appropriate fitness function, we develop an evolutionary strategy which concurrently optimizes channel assignment and power control. |
