Base station for facilitating handover in TDMA communications

Abstract

A mobile communications system including a plurality of base stations includes a plurality of mobile telephones. Each mobile telephone communicates with at least a base station from the plurality of base stations using a timeslot and a frame. The frame has a plurality of timeslots for the base station to use to communicate with various of the plurality of mobile telephones in a cell covered by the base station. Each mobile telephone has a single radio capable of communication on various frequencies. The radio is not capable of communicating on different frequencies on adjacent timeslots in a frame. A mobile telephone may establish communication with a first base station on a particular timeslot in a frame. If another timeslot is available in the frame in a second base station, communication may be established with the second base station on another timeslot in the frame. The another timeslot is not next to the particular timeslot if the frequency used on the particular timeslot and the another timeslot are different. If the frequencies used on the particular timeslot and the another timeslot are the same, communication may be established with the second base station on the another timeslot in the frame where the another timeslot is next to the particular timeslot or not next to the particular timeslot.

1 . A base station comprising: 
 a radio capable of communication with mobile telephones, the radio using frames, a frame comprising a plurality of timeslots; 
 circuitry that establishes communication with a mobile telephone and that, if the mobile telephone is in communication with another base station having a radio capable of communication with mobile telephones and the mobile telephone uses a particular timeslot in a frame to communicate with the another base station,  
 establishes communication with the mobile telephone using a timeslot not next to the particular timeslot of the frame if the frequencies used on the particular timeslot and the another timeslot are different and  
 establishes communications with the mobile telephone using a timeslot next to the particular timeslot or not next to the particular timeslot if the frequencies used on the particular timeslot and the another timeslot are the same.  
   
     
     
         2 . The base station of  claim 1 , including circuitry that reallocates a timeslot to allow the reallocated timeslot to be used by the mobile telephone.  
     
     
         3 . The base station of  claim 2 , wherein the circuitry that reallocates a timeslot reallocates the timeslot when the base station has an available timeslot next to the particular timeslot on a frequency different from the frequency used on the particular timeslot.  
     
     
         4 . The base station of  claim 2 , wherein the base station includes circuitry that provides the mobile telephone an estimate of time to prepare the another times lot for communication with the second base station.  
     
     
         5 . The base station of  claim 3 , wherein the reallocating includes assigning a second mobile telephone to communicate with the base station on a times lot other than the particular times lot and the another timeslot.  
     
     
         6 . The base station of  claim 1 , wherein the frame comprises two half frames, and each half frame includes no more than six timeslots.