PRESERVATION OF CELL BORDERS AT HAND-OFF WITHIN A SMART ANTENNA CELLULAR SYSTEM

摘要

A cellular communications network includes a plurality of cells (100) whos e base stations have both sector (104) and smart (110) antenna capabilities. While engaged in a call (200), mobile station (114) downlink signal strength measurements (202,204) are made on its own serving traffic channel and the control channe ls of neighboring cells. These measurements are then adjusted (210) by one or more factors which take into account the operational and physical differences between sector antenna and smart antenna. For example, the signal strength measurements may be appropriately adjusted by measured differences in gain between the smart antenna and sector antennna, output power backoff values associated with smart antenna a nd sector antenna support of the traffic channels in comparison to the control channel s, and power control attenuation applied to the traffic channels. The resulting adjusted downlink signal strength measurements may then be compared against each othe r (as off-set by any imposed hysteresis value) to more precisely locate the mobile station and uniformly, predictably and accurately identify when it is appropriate to authorize a hand-off