Propagation studies for mobile-to-mobile communications

This paper addresses a number of key issues that affect the modelling of propagation in mobile-to-mobile communications. Current examples of such systems include intelligent relaying, Bluetooth and other ad-hoc solutions. The key difference in mobile-to-mobile communications is that both transmit and receive antennas are likely to be closer to the ground than those in conventional cellular networks. In addition, they may also be located in less favourable propagation positions, such as in users´ pockets, bags or desk drawers. Two measurement programmes have been performed to investigate the propagation issues relating to intelligent relaying in the 2 GHz band. The first campaign concerns path loss measurements in an indoor environment where the heights of the antennas are lower than those in conventional cellular networks. The second set of data was taken to determine variations in the terminal radiation pattern given the close proximity of the human body. A number of single ray illumination measurements were performed inside an anechoic chamber. The results indicate that for the environments under consideration, an additional attenuation factor should be added to the path loss model to compensate for the unfavourable location of the terminals in a mobile-to-mobile propagation environment. This attenuation is dependent on the heights of the antennas involved, and is in the range 0-8 dB