Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE credits
To obtain statistical confidence in BLER measurements on the receiver a certain measurement time is required. This measurement time will vary depending on the BLER measured. The measurement time is a very critical parameter due to the heavy load of tests to perform and must therefore be minimized. BLER measurements are performed for the test case Receiver Demodulation Performance (Demodulation of DCH in multi-path fading propagation conditions) where the fading channel case 1, a pedestrian mobile channel with 3 km/h is considered. Measurements are done in the absence of external interference and the uplink power control is disabled. The only interference present is AWGN.
An extensive number of BLER measurements for 3,4,5,6,7,8,9 and 10 minutes are performed and the conversion of the found BLER in (%) to uncertainty in dB is done by characterization of BLER versus Eb/No. As an illustration measurement times 3, 5 and 10 minutes are selected. For the measurement time 3 minutes the corresponding statistical uncertainty is found to be ± 0.34 dB, for 5 minutes ± 0.26 dB and for 10 minutes ± 0.18 dB. 5 minutes measurement time is recommended for the 1 % BLER requirement while more than 5 minutes may be required for the BLER requirements less than 1 %. Since these BLER measurements are performed on a WCDMA radio base station the found results only apply for the WCDMA.
When performing the BLER measurements there is also another parameter, except from statistical confidence that will cause the result to alter. This is the measurement uncertainty caused by the RF instruments and the RF switch- and filter boxes. For the test case calculations of uncertainty during calibration and measurement are performed. The uncertainty, the expanded combined uncertainty, during calibration in relation to C/I is 0.23 dB while the uncertainty, the expanded combined uncertainty, and during measurement in relation to C/I is 0.30 dB. The total expanded uncertainty for the test case receiver demodulation performance is 0.49 dB.