Uplink-downlink diversity for fast cell-site selection
View Patent ↗The present invention is directed to forward link and reverse link diversity in a wireless telecommunications network. The present invention solves the reverse link/forward link dependence between a mobile station and a base station of a network by purposely selecting different base stations or sectors of a base station for reverse-link and forward-link transmissions. In one embodiment, reverse link traffic channel transmissions are targeted to a different base station than the base station from which the forward link traffic channel transmissions originate and respective control information of these channels are embedded or transmitted with the opposite link. Such diversity may be activated only in signal conditions that have a certain predefined value or mobile station locations that exhibit a sufficient chance of experiencing a forward or reverse link failure. Activation of the diversity scheme may also depend on whether more than one base station or sector has link-quality within an appropriate range or the degrading effect of the increased power on capacity is acceptable.
1. In a communications network having a plurality of sectors and a mobile station, a method for communication comprising:
establishing a connection between the mobile station and a first sector by transmitting traffic from the first sector to the mobile station on a forward link and from the mobile station to the first sector on a reverse link;
detecting an available connection between the mobile station and a second sector; and
in response to the step of detecting the available connection, dividing the forward and reverse links of the connection between the first sector and the second sector wherein traffic on the forward link is transmitted from one of the first and second sectors and traffic on the reverse link is transmitted to the other sector.
2. The method as recited in claim 1 wherein, upon the step of dividing, traffic on the forward link comprises feedback information for the reverse link and traffic on the reverse link comprises feedback information for the forward link.
3. The method as recited in claim 1 wherein the traffic comprises data and the mobile station transmits and receives feedback information to and from both the sector transmitting on the forward link and the sector for the reverse link.
4. The method as recited in claim 1 further comprising:
establishing a second reverse link for transmitting feedback information for the forward link, said second reverse link transmitting feedback information from the mobile station to the sector transmitting on the forward link; and
establishing a second forward link for transmitting feedback information for the reverse link, said second forward link transmitting feedback information from the sector for the reverse link to the mobile station.
5. The method as recited in claim 1 wherein the step of detecting the available connection comprises determining the location of the mobile station relative to the first and second sectors.
6. The method as recited in claim 5 wherein the step of determining the location of the mobile station comprises measuring the pilot strength from the first and second sectors.
7. The method as recited in claim 6 wherein the step of measuring the pilot strength from the first and second sectors comprises determining whether the pilot strengths are within a predetermined range.
8. The method as recited in claim 5 wherein the step of determining the location of the mobile station comprises measuring the pilot phase offsets from each of the first and second sectors.
9. The method as recited in claim 5 wherein the step of determining the location of the mobile station comprises obtaining a position information reading for the mobile station.
10. A mobile station in a communications network having a plurality of sectors, the mobile station comprising:
a processor programmed for establishing a connection between the mobile station and a first sector by receiving traffic from the first sector to the mobile station on a forward link and by transmitting traffic from the mobile station to the first sector on a reverse link, detecting an available connection between the mobile station and a second sector and, in response to detecting the available connection, dividing the forward and reverse links of the connection between the first sector and the second sector wherein traffic on the forward link is received from one of the first and second sectors and traffic on the reverse link is transmitted to the other sector.
11. The mobile station as recited in claim 10 wherein, upon the processor dividing the forward and reverse links, traffic on the forward link comprises feedback information for the reverse link and traffic on the reverse link comprises feedback information for the forward link.
12. The mobile station as recited in claim 10 wherein the traffic comprises data and the processor is programmed to transmit and receive feedback information to and from both the sector transmitting on the forward link and the sector for the reverse link.
13. The mobile station as recited in claim 10 wherein the processor is further programmed for establishing a second reverse link for transmitting feedback information for the forward link, said second reverse link transmitting feedback information from the mobile station to the sector transmitting on the forward link, and establishing a second forward link for transmitting feedback information for the reverse link, said second forward link transmitting feedback information from the sector for the reverse link to the mobile station.
14. The mobile station as recited in claim 10 wherein the processor is programmed to determine the location of the mobile station relative to the first and second sectors in detecting the available connection.
15. The mobile station as recited in claim 14 wherein the processor is programmed to measure the pilot strength from the first and second sectors in determining the location of the mobile station.
16. The mobile station as recited in claim 15 wherein the processor is programmed to determine whether the pilot strengths are within a predetermined range in measuring the pilot strength from the first and second sectors.
17. The mobile station as recited in claim 14 wherein the processor is programmed to measure the pilot phase offsets from each of the first and second sectors in determining the location of the mobile station.
18. The mobile station as recited in claim 14 wherein the processor is programmed to obtain a position information reading for the mobile station in determining the location of the mobile station.
19. A communications network having a plurality of sectors and a mobile station, the network comprising:
a processor programmed for establishing a connection between the mobile station and a first sector by transmitting traffic from the first sector to the mobile station on a forward link and by receiving traffic from the mobile station to the first sector on a reverse link, detecting an available connection between the mobile station and a second sector and, in response to detecting the available connection, dividing the forward and reverse links of the connection between the first sector and the second sector wherein traffic on the forward link is transmitted from one of the first and second sectors and traffic on the reverse link is received by the other sector.
20. The network as recited in claim 19 wherein, upon the processor dividing the forward and reverse links, traffic on the forward link comprises feedback information for the reverse link and traffic on the reverse link comprises feedback information for the forward link.
21. The network as recited in claim 19 wherein the traffic comprises data and the processor is programmed to transmit and receive feedback information to and from both the sector transmitting on the forward link and the sector for the reverse link.
22. The network as recited in claim 19 wherein the processor is further programmed for establishing a second reverse link for transmitting feedback information for the forward link, said second reverse link transmitting feedback information from the mobile station to the sector transmitting on the forward link, and establishing a second forward link for transmitting feedback information for the reverse link, said second forward link transmitting feedback information from the sector for the reverse link to the mobile station.
23. The network as recited in claim 19 wherein the processor is programmed to determine the location of the mobile station relative to the first and second sectors in detecting the available connection.
24. The network as recited in claim 23 wherein the processor is programmed to measure the pilot strength from the first and second sectors in determining the location of the mobile station.
25. The network as recited in claim 24 wherein the processor is programmed to determine whether the pilot strengths are within a predetermined range in measuring the pilot strength from the first and second sectors.
26. The network as recited in claim 23 wherein the processor is programmed to measure the pilot phase offsets from each of the first and second sectors in determining the location of the mobile station.
27. The network as recited in claim 23 wherein the processor is programmed to obtain a position information reading for the mobile station in determining the location of the mobile station.