Smart antennas for UMTS

With increasing mobile penetration and limited spectrum, there is a strong demand for techniques to increase capacity. Smart antenna schemes can mitigate the effects of interference and fading and increase the spectral efficiency. All of the air interface proposals for third-generation systems submitted to ETSI recommended the optional deployment of smart antennas in the network infrastructure to maximise the system capacity while retaining the required quality of service. The spectral efficiency achieved by smart antennas may be extended if the array can operate on more than one air interface. In this paper, we outline the issues related to system design of adaptive antenna candidate architectures for third-generation systems. The paper examines the use of high-speed digital signal processing (DSP) technology and software reconfigurable modules to support both TD-CDMA and W-CDMA schemes. The paper goes on to state the requirements for flexible data processing in a multi-mode base station and describes the partitioning of algorithms between parallel-processing DSP engines for the selected air interface schemes. Finally, a methodology is given for the complexity analysis of a sample demodulator and equaliser block implemented in flexible DSP, followed by extrapolation of the methodology to the dimensioning of a complete TD-CDMA receiver suitable for a smart antenna array.