Method of adjusting a timing of transmissions in a radio communication system
View Patent ↗A secondary station has a receiver capable of resolving signals received as a plurality of multipath signals from a plurality of primary stations during a soft handover process. To decode and act upon the received signals in a very short period of time, the duration of an offset between a downlink timing reference and an uplink timing reference may be varied by the secondary station. By choosing a suitable value for the offset, the secondary station can reduce the changes to the uplink timing reference. The downlink timing reference and/or the offset may be determined from the timings of received downlink signals. The secondary station may request a primary station to adjust the timing of its downlink transmissions to increase the amount of time available for processing the signals by, for example, arranging for downlink signals from the primary station supplying the strongest signal to be received first.
1. A secondary station for use in a radio communication system comprising a plurality of primary stations, the secondary station having means for engaging in a soft handover process, in which the secondary station communicates simultaneously with at least two primary stations, receiver means for receiving transmitted downlink signals from the at least two primary stations as a plurality of signals, timing measurement means for determining a downlink timing reference, and for determining an offset between the downlink timing reference and an uplink timing reference for use in the transmission of uplink signals, wherein means are provided for varying the size of the offset, wherein the timing measurement means further comprises means for determining whether a first signal path received from a primary station is received within a timing window having a lower and an upper time limit and means for requesting a primary station to alter the timing of transmissions of the primary station so that the first signal path from the primary station is received within the timing window.
2. A secondary station as claimed in claim 1 , wherein the timing measurement means further comprises means for determining timings of downlink signals received from at least one of the plurality of primary stations and means for determining downlink timing reference from said timings.
3. A secondary station as claimed in claim 1 , wherein the timing measurement means further comprises means for determining timings of downlink signals received from at least one of the plurality of primary stations and means for determining the size of the offset from said timings.
4. A secondary station as claimed in claim 1 , wherein means are provided for adjusting at least one of the upper and lower limits of the timing window to enable improved processing of the received signals by the secondary station.
5. A secondary station as claimed in claim 4 , wherein the received signals include power control commands and wherein power control means are provided for adjusting the power of uplink transmissions in response to power control commands received from the primary stations.
6. A method of operating a secondary station comprising engaging in a soft handover process, in which the secondary station communicates simultaneously with at least two primary stations, receiving transmitted downlink signals from the at least two primary stations as a plurality of signals, determining a downlink timing reference, determining an offset between the downlink timing reference and an uplink timing reference for use in the transmission of uplink signals, wherein the size of the offset is variable, and determining whether a first signal path received from a primary station is received within a timing window having a lower and an upper time limit, by requesting a primary station to alter the timing of transmissions of the primary station so that the first signal path from the primary station is received within the timing window, and by adjusting at least one of the upper and lower limits of the timing window to enable improved processing of the received signals by the secondary station.
7. A method as claimed in claim 6 , further comprising determining timings of downlink signals received from at least one of the plurality of primary stations and by determining the downlink timing reference from said timings.
8. A method as claimed in claim 6 , further comprising determining timings of downlink signals received from at least one of the plurality of primary stations and by determining the size of the offset from said timings.