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Method of supporting extended range in a TDMA system
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Inventors: Smith, David Anthony;
Assignee: Telefonaktiebolaget LM Ericsson (Stockholm, SE)
Primary Examiner: Olms; Douglas W.
Assistant Examiner: Phillips; Matthew C.
Attorney, Agent or Firm: Burns, Doane, Swecker & Mathis, L.L.P.
A method for allocating timeslots to mobile stations in a cell in a cellular communication system is disclosed. First, the distance each mobile station is from a base station in the cell is determined. Then each mobile station is assigned a timeslot based upon the distance each mobile station is from the base station, wherein the timeslots within a contiguous group of timeslots are assigned to the mobile stations in the order of the mobile stations increasing distance from the base station and at least one timeslot at the back of the contiguous group is not assigned so as to allow bursts from the mobile stations to slide into the next timeslot. |
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DETAILED DESCRIPTION It is an object of the present invention to provide a method for extending the range of a TDMA system without drastically compromising the capacity of the cellular system.
This object is accomplished by overcoming the need for an idle timeslot for each specific burst to slide back into, by allocating timeslots to mobile stations at least partly based on the distance each mobile station is from a base station.
One of the novel principles of this method is that since the mobiles are rigorously ordered in increasing distance order, either physical or virtual distance.
In the present invention, the uplink burst from the most distant mobile station, at extreme range will slide backwards into the idle timeslot or timeslots at the back of the extended range group.
This will in turn vacate the front of that burst's nominal timeslot, allowing the preceding burst from a closer mobile station to slide back.
Since the timeslots are allocated according to the distance between the mobile and base station, the mobile station using the preceding timeslot is known to be closer, and thus its burst will not slide back so far, and thus cannot overlap with the burst from the most distant mobile station.
This principle repeats back through all timeslots until the mobile closest to the BTS is reached.
According to one embodiment of the present invention, a method for allocating timeslots to mobile stations in a cell in a cellular communication system is disclosed.
First, the distance from each of a plurality of mobile stations to the base station is determined.
Normal timeslots may exist in isolation and be assigned as today, however a group of three or more contiguous timeslots may be utilized as an extended range group.
This group may begin with any timeslot allowing for the fact that timeslots 7 and 0 are contiguous in a TDMA system with 8 timeslots per frame, such as GSM.
Mobile stations are allocated timeslots within the extended range group according to the order of their distance from the base station, the closest mobile station being at the front of the extended range group of timeslots and the unused timeslots are idle, that are not filled, and no carrier is transmitted
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Multiplexer-related 
