| 摘要 |
<p>A group of cells (2, fig. 1) e.g. picocells or microcells, within the coverage (11, fig. 1) of a common simulcast carrier or umbrella cell, each transmit an identical broadcast signal on the same simulcast carrier frequency f5. A mobile station (4, 4', fig. 1) in this communication network, is arranged to intermittently perform an intracellular handover to the common simulcast carrier, that is, to an uplink timeslot TS2 on the simulcast carrier frequency and while the mobile is using the common simulcast carrier, measurements of the radio environment are performed. For example, a mobile station in a call using a timeslot TS1 in a traffic frequency f2 different from the simulcast carrier frequency f5 receives a control signal (5, fig. 1) on the carrier f5, generated possibly in response to detection of a low signal level or quality, that instructs the mobile to handover to the simulcast carrier frequency TS2. The timeslot freed in the traffic channel TS1 is then available to the picocellular head (1, fig. 1) for interference measurements to assist in frequency allocation between the network cells. Alternatively all the picocellular heads in the simulcast cells may make uplink measurements on the mobile using the simulcast carrier f5, to determine the best picocell for handover. The mobile may also be arranged to be assigned temporarily to the simulcast carrier when it originates a call, allowing uplink measurements to be made to select the most appropriate cell. Arrangements avoids frequency ambiguities associated with downlink measurements made by mobile stations prior to handover in conventional simulcast systems.</p> |
