Methods and systems for mobile terminal assisted handover in an private radio communications network

DETAILED DESCRIPTION It is, therefore, an objective of the present invention to resolve the problem of providing handover functions in a private radio communications network using a TDMA protocol such as a GSM-compatible air interface while limiting the amount of control channel traffic to reduce the potential for interference.
The present invention provides for a private radio communications network in which all radio base stations of the private network are synchronized up to the multiframe level and transmit a beacon on a beacon channel during the idle frames of a traffic connection.
During the idle frames, the mobile terminal performs measurements to find surrounding private base stations within the private radio communications network which might be better candidates to connect to.
If the beacon transmissions from the base stations jitter somewhat within the idle frames the mobile terminal waits on at least one fixed time slot position in the idle frame for a beacon to arrive.
In addition, at different occasions, the mobile terminal can scan different frequencies for beacons.
Because the private radio base stations are roughly synchronized, the decoding of a beacon burst can be performed by the mobile terminal as long as no collisions occur between beacons.
From decoding the beacon, the base color code (BCC) of the base station can be derived by the mobile terminal.
Measurements of the received signal strength and the corresponding BCCs can then be transferred from the mobile terminal to the private radio communications network by the connected private radio base station by applying the standard associated control channels (e.
g.
, FACCH or SACCH) defined for the private radio communications network.
Based on the mobile terminal reports, the private radio communications network may decide on handing over the mobile terminal to another radio base station within the private radio communications network.
In one embodiment, the private radio communications network of the present invention provides for handover of a TDMA frame number based encryption connection, such as is provided for in GSM, without including a TDMA frame number broadcast by the base station on its beacon channel