Propagation research for millimetrewave cellular systems

Trials are already under way for commercial, digital cellular television (MVDS) services in the CEPT approved band of 40.5-42.5 GHz. The attraction of these frequencies is the availability of spectrum that will support the wide bandwidth required by the new services. However, the service availability, and hence the commercial viability, depends to a much greater extent than at lower frequencies on the propagation effects. Rutherford Appleton Laboratory is leading the propagation work. One broad aim is the provision of models and design tools for the broadband cellular radio network that can be used to predict the number of users per cell that a given cellular architecture can serve, taking account of the degradations due to the propagation channel. At 42 GHz (and other relevant millimetric frequencies such as 28-29 GHz which is preferred in North America), the main propagation mechanisms of interest are: (a) for coverage within a cell: rain and atmospheric gases (time variable); building and terrain obstruction, multipath and vegetation effects (location variable); and (b) for interference between cells: clear-air enhancements (time variable); and building and terrain obstruction (location variable). Some aspects of these are discussed.