Özet:
Mobile communication systems have limited frequency resources and macrocellular architecture utilizes smaller one tier cells to gain frequency reuse. One approach to enhance the overall system capacity is to use two tier femtocell-macrocell systems. The introduction of femtocells has caused a great excitement in that the femtocell system can be a solution to poor indoor coverage for mobile communications. Since femtocells are plug-and-play devices and not deployed with central planning, the handover systems used in one tier macrocell infrastructure should be updated according to the needs of two tier femtocell-macrocell systems. Femtocell base stations utilize the broadband Internet connection to connect to the operator core network. Since the Internet is a lossy network incapable of guaranteeing the quality service requirements of real time voice communications over Internet Protocol (IP) networks, the handover systems based only on the wireless received signal strength are unable to provide a solution to the quality requirements of wired systems. The quality of service requirements for wireless and wired medium are both taken into account to maintain a better call quality in the novel handover algorithms in this study. The handover rate and the signal degradation rate are the key performance indicators of the handover system optimization. The simulation studies demonstrate that better results are achieved with the proposed algorithms compared to existing ones in the literature.
