Cooperation between the GVWS within a few hundred meters has forced MWRs equipped to have service ranges in such a short ranges as well as the limited numbers of channels are available. This kind of situation often produces the frequency interferences between MWRs due to the easy uses of the common and adjacent frequencies between them. Current work provides the details of the frequency interferences and the possible degrees of detections. It is also described that the effective distances for the operation between the GVWS are investigated when they use the common and the adjacent frequencies each other with the factors as the frequency intervals and the antenna arrangement angles.