Radio Resource Management Strategies for Distributed Antenna Systems

With the increasing throughput demands of wireless users, operators will need to build wireless networks with significantly larger capacities than those presently available. Therefore for the next generation of wireless networks (4G) a significant effort is being placed on increased spectral efficiencies. One means of achieving higher spectral efficiencies is through the use of Distributed Antenna Systems (DAS) whereby a single basestation controls transmissions from multiple geographically distributed antennas. This allows for the placement of the antennas closer to the UEs (User Equipments) so as to use reduced transmission power while at the same time increasing the spatial diversity of the transmissions from such antennas. In this paper we investigate various strategies for serving UEs using DAS. In particular, we investigate the traditional frequency reuse one and orthogonal frequency allocation schemes as well multipoint transmission schemes in which multiple transmitters can be used to serve a single user. In order to gain some intuition on the effectiveness of each approach we analyze a simple network model and show that, in practice, it may be possible to reduce the set of strategies one uses when serving users by removing those strategies that are optimal in only small regions of the cell. We use simulations to further support our conclusions. We believe that the effectiveness of DAS depends on the radio resource management applied and that investigations such as those in this paper can increase our intuition in this area.