Importance

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Abstract

A method of providing direct communication between a pair of mobile stations over a single voice channel is disclosed, as well as a novel mobile station equipped with the capability to function in a so-called base-station-emulation (BSE) mode. A mobile switching center (MSC) first determines whether direct communication between two mobile stations is possible, by verifying that at least one of them can function in BSE mode. The MSC then establishes whether a clear radio link between the two mobile stations can be established and assigns a single voice channel for the conversation. In this way, the number of base station transceivers required to service a cell can be reduced. If the locations of the two mobile stations are known, feasibility of direct communication can be easily determined. Optionally, the MSC might order the two mobile stations to exchange modulated audio tones and report measured received signal strengths. Direct communication is then established subject to an evaluation by the MSC. The one mobile station chosen to operate in BSE mode is ordered to 'swap' its transmit and receive frequencies, and the direct call is begun. Termination of the call by the mobile station that has remained in 'normal' mode is detected by the mobile station in BSE mode, and termination of the call by the mobile station in BSE mode is detected by the base station.

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First Claim