Handover for cellular radio systems
View Patent ↗In a cellular wireless system, power thresholds used for determining whether to add or drop servers held in a set of servers, such as an active set, for serving a user equipment (UE) are determined based on the motion of the respective UE. A lower threshold may be used with respect to the adding or dropping of a given server to or from a set of servers for serving a fast moving UE than would be used for the same server with respect to adding or dropping to or from a set of servers for serving a slow moving UE, while maintaining a given quality of service. As a result, the average number of servers held in sets is reduced in a typical network that comprises a plurality of UEs moving at different speeds, compared to a situation in which the threshold is set irrespective of the motion of a UE.
1. A method comprising:
measuring signal power received at a user equipment connected to a base station from at least one other base station from a plurality of base stations;
evaluating a factor indicative of the speed of the user equipment;
determining an adjustment component dependent on the factor;
determining a threshold of signal power for the signal from the at least one other base station; and
determining whether or not the at least one other base station should be added to a set of active base stations on the basis of the threshold and the adjustment component.
2. The method according to claim 1 , wherein the user equipment operates in accordance with a long term evolution system.
3. The method according to claim 1 , wherein the adjustment component is 3 dB.
4. The method according to claim 1 , wherein the adjustment component is 6 dB.
5. The method according to claim 1 , wherein the adjustment component varies according to the factor.
6. The method according to claim 1 , wherein the adjustment component is 6 dB when the evaluated factor indicates that the speed of the user equipment is high.
7. The method according to claim 1 , further comprising sending at least one indication of signal strength.
8. The method according to claim 1 , further comprising determining the factor from the rate of change of the strength of the signal received from the least one other base station from a plurality of base stations.
9. A user equipment connected to a base station configured to:
measure signal power received at the user equipment from at least one other base station from a plurality of base stations;
evaluate a factor indicative of the speed of the user equipment;
determine an adjustment component dependent on the factor;
determine a threshold of signal power for the signal from the at least one other base station; and
determine whether or not the at least one other base station should be added to a set of active base stations on the basis of the threshold and the adjustment component.
10. The user equipment according to claim 9 , wherein the user equipment operates in accordance with a long term evolution system.
11. The user equipment according to claim 9 , wherein the adjustment component is 3 dB.
12. The user equipment according to claim 9 , wherein the adjustment component is 6 dB.
13. The user equipment according to claim 9 , wherein the adjustment component varies according to the factor.
14. The user equipment according to claim 9 , wherein the adjustment component is 6 dB when the evaluated factor indicates that the speed of the user equipment is high.
15. The user equipment according to claim 9 , further configured to send at least one indication of signal strength.
16. The user equipment according to claim 9 , further configured to determine the factor from the rate of change of the strength of the signal received from the least one other base station from a plurality of base stations.