Maintaining QoS by utilizing hierarchical wireless systems

Future wireless networks, the systems beyond 3G, will be a combination of different wireless systems. With only one terminal a user should be able to connect to different type of operators, technologies and systems. The issue is also to make the terminal staying online connected, when these changes are made. Both intrasystem handovers and intersystem handovers should be supported by such terminals. The systems will form a hierarchical cell structure, that offer the users several technologies and different type of QoS-levels and bandwidths. To analyze this type of hierarchical cell structure a model has been created, and to verify the model calculations on a Markov-chain have been made. Using the transition probabilities we have calculated the state probabilities, to verify the results from the simulations made of our model. The analytical model and the simulation shows a very good agreement. The results show that the model could be used to show how the WLAN usage will behave as the number of WLANs and WLAN users increase.