Abstract: A repeater system in a communication system including a base station and a mobile unit provides a communications link between the base station and the mobile unit when the mobile unit is located in an environment that is substantially closed off to high radio frequency communication between the base station and the mobile unit. The repeater system has a first linear two-way frequency converter including a high frequency port for two-way coupling to the base station and a low frequency port for two-way coupling to a low frequency signal that is capable of distributing radio frequency power through the closed environment. The low frequency port is connected to a cable which propagates and receives low radio frequency power within the closed environment.

Abstract: A method of reducing in a digital time multiplex mobile telephony system the risk of poor reception as a result of the occurrence of points of low signal strength, so-called zero points. Transmission from fixed stations is performed with a polarization direction which is changed stepwise between different parts of the transmitted information. This causes the fading patterns around receiving stations to change in time, and also causes any zero points to be moved in the geography, therewith making it improbable that more than a small part of an information frame will be lost. In the case of a GSM-type system, the polarization direction is changed for each new TDMA-frame.