Method of handling over a call between two relay stations of a cell of a

Abstract

A method is described of handing over calls between two relay stations, respectively a current relay station and a target relay station in the same cell of a digital cellular mobile radio system, the cell being associated with a base transceiver station comprising a plurality of relay stations including the current and target relay stations and geographically distributed within the cell. Each relay station comprises at least one antenna connected to at least one transmit/receive device. Each relay station has a plurality of traffic channels and a plurality of associated signaling channels. A call being set up for a mobile station is allocated, from the channels of the current relay station, at least one current traffic channel and at least one current associated signaling channel. The plurality of relay stations shares at least one particular traffic channel, constituting a shared traffic channel, which is reserved at least partly for handover. The method includes a first handover phase in which the shared traffic channel is a first target traffic channel. The first phase includes the following successive steps: sending by the mobile station of at least one test message to the plurality of relay stations via the shared traffic channel, and selection by the system of the target relay station from the plurality of relay stations, in accordance with at least one predetermined selection criterion based on at least one parameter associated with the quality of reception of the at least one test message. The method also includes a second handover phase with a traffic channel associated with the target relay station as a second target traffic channel.