Resource Management In 3G Systems Employing Smart Antennas

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Virginia Tech

Modern mobile communication systems will provide enhanced high-speed data, multimedia, and voice services to mobile users. The integration of such heterogeneous traffic types implies that the network must provide differentiated Quality of Service (QoS). Beam forming techniques have been proposed to increase the spectral efficiency of the wireless channel. Using beamforming in the network will lead to intra-cell handoffs within the cell due to user mobility. In a commercially deployed next generation cellular system, it is likely that beam forming and QoS guarantees to the users will co-exist. In this work we propose a resource allocation and management scheme tailored for a network that employs smart antennas in support of a heterogeneous user mix.

Resource management in a wireless system should take care of channel impairments and non-ideal antenna patterns. Mobile users moving from one beam to the other give rise to resource reallocation issues. Depending on the scatterer distribution in the cell, the Angle of Arrival (AoA) of the users will also change, affecting the interference pattern in the cell. In a system with data and multimedia users, some of the users are likely to be elastic in their demands for bandwidth. In this work, we propose a resource allocation and management scheme tailored for systems with smart antennas having heterogeneous users. The algorithm works by comparing the received power in the beams. Elasticity of user requirement for data services is exploited to provide adaptive QoS, thereby reducing the call dropping probability due to user mobility.

Simulation results showing the channel and Multiple Access Interference (MAI) effects on system performance are presented. The effect of channel coding to provide Bit Error Rate (BER) guarantees is studied. We also show the throughput advantage obtained using the resource management algorithms. It is also seen that the throughput of the system increases for a user population having a higher elasticity. A modified resource allocation algorithm to reduce the blocking probability of the calls is presented and performance verified using simulation. The probability of call dropping in an unmanaged system due to user mobility is shown. Our studies show that using managed system the call drop probability can be minimized.

WCDMA, resource management, Resource allocation, QoS, Smart antennas, 3G