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Background

The radio spectrum is a limited resource and can only be used optimally if compatibility is assured between radiocommunications systems located in the same or adjacent frequency bands. For example, an important criterion for radio compatibility is the difference between the wanted and unwanted signal levels in the victim receiver input. This parameter is used to derive a separation between the victim and interfering systems or services in geographical space or frequency domain. Considering only the adjacent bands, the most significant interference mechanisms are the unwanted emissions from the transmitters as well as blocking and intermodulation in the victim receiver.

The classical approach for the estimation of these interference mechanisms is the Minimum Coupling Loss (MCL) method. However the essentially analytical MCL method appears being too rigid and difficult to implement in many cases, where operation of radiocommunications systems may not be described in static terms, e.g. due to random nature of operation of user terminals in the mobile systems. While compromise in such cases may be found by making certain (pessimistic) assumptions and simplifications on the operation of the considered systems, this may produce unnecessarily stiff and static interference assessment, which becomes often biased towards one of the considered systems depending on the priorities taken in making those assumptions/simplifications.

Within the frame of the CEPT Working Group Spectrum Engineering, a statistical simulation model has been developed based on the Monte-Carlo method, named SEAMCAT® (Spectrum Engineering Advanced Monte-Carlo Analysis Tool). This model and its supporting software implementation allowed quick yet reliable consideration of spatial and temporal distributions of the received signals and the resulting statistical probability of interference in a wide variety of scenarios. It therefore enabled more precise mutual positioning of those considered systems, hence more efficient use of the radio spectrum.

The original SEAMCAT tool was created using the C++ programming language in two phases spanning the years 1997-2002, the latest version from that development (referred to as SEAMCAT-2) is still available for free downloads from ERO web site at  www.ero.dk/seamcat .

However, in 2003 it was realised that the SEAMCAT-2 did no longer provide sufficient universality as it was not suitable for direct simulation of proliferating CDMA systems, notably due to the complex power control mechanisms employed in those systems. Therefore the upgrade of SEAMCAT tool was agreed with the detailed specifications approved by the end of 2003, and the software development of SEAMCAT-3 started soon afterwards. The main aims for the upgrade were the following:

• Porting of software to open Java® platform, with introduction of Live Web update and similar new functionalities;
• Improvement of interactivity of simulations through the graphic representation of scenarios;
• Implementation of algorithms for direct simulation of CDMA systems, both as victim and interferer;
• Implementation of plug-in modularity (initially for user-defined propagation models);
• Improved functionality for complex simulations (unlimited number of batch parameters, remote computing).

The development SEAMCAT-3 was finalised at the beginning of 2005, and after some Bet-testing it became an official SEAMCAT release since the end of 2005.