## Orthogonality loss factor, total interference factor and Bit Error Rate (BER) estimation on a UMTS/FDD network

Providing the operators with a measure of the quality of the downlink transmissions is very useful, because it gives a good picture of the impact of the network deployment on the performance. As mobile receivers will probably use conventional RAKE receivers in order to demodulate the transmitted symbols, we propose to estimate from the received signals the signal to interference plus noise ratio (SINR) at the output of such a receiver. To do so, we showed that the SINR can be expressed in closed form in terms of the channel impulse responses between the active base stations and the receiver, and from the total power transmitted by each active base station. Using high quality CIR estimation schemes thus allows evaluating the SINR, and thus the corresponding bit error rate. One of the interest is that from measurements performed at one given time with a given network load, the formula allows to extrapolate the obtained BER for different loads of each detected BTS and thus to deduce capacity estimation.

Moreover, one of the originality of the ANTIUM tool is that it provides the operator with different valuable factors that other classical tools do not produce. These factors, directly extracted from the SINR formula are the orthogonality loss factor (characterising the intra cell interference due to multi-path propagation) and the total interference factor (characterising both intra-cell and extra-cell interference). Operators commonly use the Ec/I0 as a criterion for network planning. The total interference factor appeared to be more efficient criterion that is directly linked with a mobile performance. This factor does not depend on the traffic load of the network at the measurement moment and it accurately takes into account the propagation characteristics, the mobile Rake processing and soft hand-over configurations.

Moreover, one of the originality of the ANTIUM tool is that it provides the operator with different valuable factors that other classical tools do not produce. These factors, directly extracted from the SINR formula are the orthogonality loss factor (characterising the intra cell interference due to multi-path propagation) and the total interference factor (characterising both intra-cell and extra-cell interference). Operators commonly use the Ec/I0 as a criterion for network planning. The total interference factor appeared to be more efficient criterion that is directly linked with a mobile performance. This factor does not depend on the traffic load of the network at the measurement moment and it accurately takes into account the propagation characteristics, the mobile Rake processing and soft hand-over configurations.