Low complexity spatial interpolation for cellular coverage analysis

During the last decade a lot of effort has been spent on cellular network optimization to improve network capacity and end-user Quality of Service (QoS). Coverage analysis remains as one of the essential topics on which mobile operators still need innovation in terms of performance and cost. Manual coverage analysis is an inefficient and costly task. Radio Environment Maps (REMs) is an efficient coverage analysis solution for present-day cellular networks. REM concept consists of spatially interpolating geo-located measurements to build the whole coverage map using a spatial interpolation technique originating from geo-statistics. Kriging is such a powerful technique which results in high performance in terms of prediction quality. However, this method is costly in terms of computational complexity especially for large datasets: computational complexity of Kriging is O(n³) where n is the number of measurements. This paper proposes the application of a variant of Kriging, Fixed Rank Kriging (FRK), to coverage analysis in order to reduce the computational complexity of the spatial interpolation while keeping an acceptable prediction error.