N.2 Correlation and antenna gain imbalance

3GPP45.005GSM/EDGE Radio transmission and receptionTS

Since a DARP phase II MS utilizes receiver diversity by means of two antennas, a set of diversity specific parameters have been defined. The sets consist of different values of antenna correlation and antenna gain imbalance.

Table N.2-1 DARP phase II diversity parameters

Parameter set	Antenna correlation,	Antenna gain imbalance, G
Set 1	0	0 dB
Set 2	0.7	-6 dB

The correlation is defined as the magnitude of the complex correlation of the signals received at the two antenna connectors of the MS. A correlation value of 0 means the signals are uncorrelated. The antenna gain imbalance parameter reflects the difference in received signal level at the two antenna connectors. Thus, a value of -6 dB means that the signal on one antenna is attenuated by 6 dB compared to the signal on the other connector. The channel model setup when applying these parameters is illustrated below, where the parameter, G, models the antenna gain imbalance and is the antenna correlation.

Figure N.2.1: Single input – dual output channel model for MS Receiver Diversity – DARP ph II

The model consists of a single input signal, which is passed through two fading channels. The multipath fading is independent Rayleigh fading processes but the channel profile, e.g. TU50 is the same for each branch. The correlation between the two branches is generated using the weighting factor, , which as mentioned is the magnitude of the complex correlation. Antenna gain imbalance is applied by attenuating Y₁ or Y₂ by 6 dB as indicated by the G block on figure N.2.1.

The multi interferer scenarios (DTS-2 and DTS-5) are generated by expanding the single input-dual output model as shown below. The model uses instances of the single input dual output channel model to instantiate the interfering signals. For sensitivity tests the single input – dual output channel model of figure N.2.1 is sufficient.

Figure N.2.2: Multi interferer model for MS Receiver Diversity – DARP ph II. The amplifier G represents the antenna gain imbalance parameter.