Review on Ray Tracing Channel Simulation Accuracy in Sub-6 GHz Outdoor Deployment Scenarios

In this article, a review of the achieved accuracy in the literature for ray tracing (RT) based channel modeling is presented with a focus on outdoor propagation scenarios in the sub-6 GHz frequency range. The achieved accuracy is analyzed from three perspectives: 1) The input parameters which include the environmental description in the form of digital maps and the corresponding constitutive material parameters; 2) from the interaction mechanisms perspective and 3) from the output perspective where the achieved accuracy of predicted path loss is reviewed. Uniform assignment of materials to the entire propagation scenario is observed in most of the works in the literature which is attributed to the composite nature of common building materials and the difficulty of characterizing all material properties especially for outdoor scenarios. The digital maps are shown to introduce a certain degree of uncertainty in the RT predictions as most common sources of the maps hardly publish the accuracy. Notwithstanding, the prediction of path loss in most RT tools is observed to be rather robust against the inaccuracies in the input parameters with most RT tools achieving a prediction accuracy with a mean error below 4 dB and a standard deviation (STD) below 8 dB.