A flexible mobility-aware transmission scheme utilizing smart antennas in a wireless cellular network

The properties of the radio transmission channel, and consequently the performance of a mobile radio network, are highly sensible to the movements of the users. The user behaviour influences the link quality, cell dwell times, handover rates, outage probability, etc. Existing networks as, e.g., the Global System for Mobile Communications (GSM) have a rather fixed structure. They can only adapt the modem to the permanently changing channel conditions, but are not able to reconfigure the network resources according to the mobility of the users. The Integrated Broadband Mobile System (IBMS) concept provides a trade-off between data rate and mobility by means of a set of transmission classes that use smart antennas in different configurations, including smart antennas at both the base and the mobile site. It is shown how capacity can be increased by switching between the classes according to the user mobility. If, however, a single transmission class is considered, smart antennas employed at the mobile terminal have a negative impact on the network capacity. It is demonstrated that this behaviour is inherent to the topology of a cellular network. But IBMS provides the potential to overcome this peculiarity due to its intrinsic structure.