Interference Model
The ITU-R M.2101 specifies that the ACIR (Adjacent Channel Interference Ratio) should be calculated based on per UE allocated RB (Resource Blocks).
Adjacent Channel Leakage Ratio (ACLR) and Adjacent Channel Selectivity (ACS) are critical performance metrics. However, both ACLR and ACS values are typically specified as single figures in standards, with no clear method for compensation.
While techniques such as Frequency Dependent Rejection (FDR) have been proposed, their effectiveness is limited without a well-defined receiving mask.
"Transmit spectrum masks are readily available via standardization documents, but these requirements do not generally extend to receivers. There is often reluctance by system operators to provide the receiver filter as it can reveal sensitive information about their network." (Interference Analysis Modelling Radio Systems for Spectrum Management, John Pahl Wiley - 2016).
The following model is used to compute the total interference power into the IMT UEs.
When analyzing UE (User Equipment) as a victim in adjacent channel scenarios, or even in certain co-channel scenarios, it is crucial to account for variations in received interference power among different UEs.
Following are examples depicting how the interference is computed in the simulator where the IMT-DL (UE) is the interfered-with system.
Here the interferer emission-mask is used to calculate the amount of power into the UEs 1, 2, and 3.
When there is partial channel overlap, the amount of interference power for each UE in the overlap region is calculated as a weight factor between the overlapped band and the UE RBs band.
In the following example, UE1 receives part of the in-band power from the interferer system. Whereas UEs 1 and 2 receives interference from the OOB emissions.
This example is similar to the partial channel overlap. The amount of interference power for each UE in the overlap region is calculated as a weight factor between the overlapped band and the UE RBs band. UE1 weight factor is equal to 1, and UE2 weight factor is 0.5. UE3 is in the OOB emission domain.
