Planning and optimisation of smart antenna base stations in 3G networks

In the initial UMTS infrastructure deployment, sector antenna-equipped base sites will predominate. It is likely that the first switched-beam antenna products will be available in 2001/2, when build out is underway. Operators may choose to replace sector antennas for switched beam units on some sites where traffic demand is expected to be very high. The 'smart sectorisation' of a site's coverage area afforded by this type of smart antenna product can be used to enhance capacity by reducing overall interference levels. This is a kind of SFIR (spatial filtering for interference reduction). Early in UMTS Phase 1, fully adaptive antennas will become available to network operators. This class of smart antenna offers enhanced SFIR capability relative to that of the switched beam units, and additionally offers the possibility of single-cell frequency reuse, SDMA (space division multiple access). In SDMA, the network capacity is increased via a double benefit of optimum/switched beamforming. Firstly, overall interference levels are reduced as a result of more closely targeting power toward the terminal of interest. Secondly, optimal minimisation of unwanted power from non-served terminals allows scarce short channelisation codes to be reused by high data-rate users within the coverage area of the same cell. Planning tools for 3G networks will harness the potential of these revolutionary changes in network infrastructure, and additionally will alleviate the complexity for the radio planner of handling a multiservice, multi-bearer environment.