 smaller radius is preferred. Therefore it is necessary to which is achieved by an experiment. For any true find a compromise between the minimum CRLB and the azimuth/elevation pair Q, I within the coverage sector of optimum beamformer. the SPUCPA the azimuth was estimated by an ML procedure [Rich05], [ThLR04]. This experiment was repeated 64 times. The noise level for CRLB calculation Evaluation of real antenna arrays was adjusted to match the observed device noise level Once the antenna array is realised it can be measured in an which was held constant according to a SNR in the main anechoic chamber. The antenna response is described by beam direction (V = 90 deg) of 17-18 dB. It is also the complex polarimetric beam patterns of all elements shown that this evaluation method is valid in the case of which result from vertical and horizontal polarised exci- more complicated scenarios. tation. Recording of the complete spherical beam pattern Further, the described method can be used for the ML requires precise rotation of the array around a suitable parameter estimation as clarified in [TLRT05b], defined pivot point located in the phase reference centre [ThLR04], [Rich05]. Here it is used to define the fun- of the array and excellent phase stability of the set-up. The damental limit of the achievable variance of the esti- measured beam patterns are discrete in azimuth and mated DoA/DoD parameters in terms of the CRLB to Propagation modelling and channel characterisation CHAPTER 4.7 X 10-3 X 10-3 Azimuth Azimuth o (deg) (deg) Elevation V (deg) Elevation V (deg) Figure 4.7-30 CRLB (left) and estimated variance (right) of estimated azimuth DoA VS. the true azimuth and elevation direction range. check the reliability of the obtained parameters during of the literature on channel characterisation, from oper- the estimation process. ations on time series. In this way, the following is Another approach for evaluating the performance implicitly assumed [Bult04]: multidimensional channel sounding is presented in the measur