Alcatel Cit

Alcatel

Alcatel Mobile Communication France

Corinne Cherpantier

Pierre Dupuy

Max Dobrosielski

Laurent Girardeau

Laurent Julia

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.

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

A system for synchronizing base transceiver stations includes a reference base transceiver station and a subordinate base transceiver station. Each base transceiver station has a clocks with the same frequency but any relative phase, and a timing reference. The reference base transceiver station imposes its own timing reference on each subordinate base transceiver station to compensate the phase difference between the two stations. The timing reference is imposed by having a mobile station listen to the reference base transceiver station and the subordinate base transceiver station, deducing a time shift D1 between the two base transceiver stations from the perspective of the mobile, determining a propagation time difference D2 between the mobile and the reference base transceiver station and the subordinate base transceiver station upon the occurrence of a handover that involves the reference base transceiver station. From D1 and D2 there can be determined the time shift to be used in order to synchronize the subordinate to the reference base transceiver station.

Base transceiver station for cellular mobile radio system and system for

In a TDMA type cellular mobile radio system frequencies are shared between cells of the same re-use pattern and frequency hopping is used so that the frequency used at any time in one of the cells of a re-use pattern is different from those used at the same time in the other cells of that pattern. A base transceiver station of this system commands the sending of one of the frequencies shared in this way during a part of the time division multiple access frame and commands the stopping of all sending during the other part of the frame. This other part of the frame has a duration at least equal to the relative synchronization error between base transceiver stations of the system

In a combined time-division multiple access and frequency-division multiple access multilayer cellular mobile radio network comprising macrocells and microcells, each macrocell being associated with at least one control frequency and at least one traffic frequency and each microcell being associated with at least one control frequency, a method of optimizing frequency use when adding any microcell base station defining a given microcell that is part of a coverage area of a given macrocell includes the step of allocating to said microcell a control frequency identical to a traffic frequency used in a macrocell immediately adjacent said given macrocell.

Multilayer cellular mobile radio network with optimized frequency re-use

A cell level change control device for cellular mobile radio networks with more than one level of cells includes means for comparing the value of a parameter representative of the speed of a mobile station with a threshold in order to decide if it is necessary to command a cell level change when the mobile station is served by a lower level cell contained in a higher level cell or when a mobile station is served by a higher level cell and it is determined that the lower level cell contained in that higher level cell constitutes the best cell. The device determines the load of the higher level cell and varies the threshold in accordance with the load.

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Garches, France

Corinne Cherpantier