Abstract: The location of mobile unit cellular radio system is determined by determining the differences in timing of a characteristic feature of the transmission of the control channel of each of a plurality of base stations as measured at the mobile unit. The characteristic feature may, for example, be the training signal already used by the mobile unit in a cellular system to measure signal strength in handover operations. By determining the differences between time of arrival of transmissions from four base stations, location in two dimensions can be derived without prior knowledge of the actual distance to any of the base stations. A fifth base station allows location in three dimensions to be determined.

Abstract: A cellular radio system includes radio base stations, each having an allocated number of radio channels. Each radio base station is connected to the rest of the network by a branched network. At a branch point an intermediate switch is provided for connecting channels in the trunk portion to channels in the branches. The capacity of the trunk link is less than the total capacity of the base stations (and of their associated branch links). At times when one or more of the base stations have surplus capacity, that capacity is disabled so that the capacity of the trunk link is not exceeded. The capacity of each base station may be varied according to predicted or actual demand, provided that the total (non-disabled) capacity of the base stations does not exceed that of the trunk link.

Abstract: Mobile radio units communicate at a lower bit-rate than the conventional switching rate of a fixed network. Such calls are identified by mobile-to-mobile recognizers which identify characteristic bit streams and handle calls appropriately. An incoming mobile-to-mobile recognizer normally routes the call to a digital to A-law transcoder. An outgoing mobile-to-mobile recognizer normally routes calls to a high bit-rate digital to A-law transcoder. If a call is established between two mobile users the first--mobile-to-mobile recognizer diverts the signal received to a bit stuffer which provides three null bits for every bit received over the air interface. The null bits may be random numbers, but preferably include a recognizable pattern which can be detected by the second mobile-to-mobile recognizer. By such "bit sutffing" a 64 kbit/s signal can be generated from a 16 kbit/s signal with minimal signal processing and without the need to transcode to A-law and back.