Automatic Frequency Planning in FD/TDMA mobile networks

CHASS - Channel Assignment.



Frequency planning which needs manual interaction is crude and inefficient, because it is time consuming and needs a long, often iterative process to find an acceptable design. Moreover, it is highly inflexible concerning new demands, extensions or modifications, due to the fast development and dynamic nature of mobile networks. Worst of all, heuristically or manually determined frequency allocations are often far away from the system optimum. Optimal solutions, however, are of paramount importance, if a network comes close to its capacity bound. Effective usage of the scarce radio spectrum leads to both better network quality and increased capacity.


Tool description:

  • CHASS is an automatic frequency planning tool based on highly sophisticated mathematical programming techniques, capable of achieving solutions of superb quality. Basic input data for CHASS are pair wise interference probabilities between cells, possibly obtained from CORLA.

  • CHASS is fast. It offers a first solution within seconds. The iterative optimization time can be controlled by the user. Excellent solutions are usually obtained after a few minutes. The number of cells may be huge. For real instances with more than 5000 cells, channels have been assigned to the operator's full satisfaction.


Several benchmark tests have been performed on a European project (COST 259) and a network operator's internal basis. Our method outperformed all of the competing tools by approximately 30%. Usually this results in a significant capacity gain without changing the core structure of your network. Convinced? If not, we would be more than happy to carry out some tests with data from your network.

Interference graph before optimization

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Interference graph after optimization

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  • Offers a the simple, easy-to-use graphical user interface and is perfectly suited to be used as an Add-On in leading GIS and radio network planning software tools.



  • As a unique feature, CHASS is able to allocate additional channels with minimal interference in an existing network, while the user has control of the number of neighboring cells which may be subject to frequency changes. The objective function also includes discontinuous transmission and frequency hopping.


Your benefits:

  • Use the scarce radio spectrum effectively and increase both network quality and capacity.


  • The algorithm is presently used by Vodafone D2.