Intracell handover with antenna arrays

• US 5,848,358 A
• Filed: 10/31/1996
• Issued: 12/08/1998
• Est. Priority Date: 06/23/1994
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Gudmundsson, Bjorn, Forssen, Ulf
• Primary Examiner(s): Urban, Edward F.
• Application Number:
  US08/741,948
• Time in Patent Office: 768 Days
• Field of Search: 455/33.2, 455/33.3, 455/33.4, 455/54.1, 455/54.2, 455/56.1, 455/62, 455/63, 455/34.1, 455/34.2, 455/436, 455/437, 455/450, 455/562, 379/59, 379/60, 370/334
• US Class Current: 455/437
• CPC Class Codes: H04W 16/24 Cell structures
• CPC Class Codes: H04W 36/06 Reselecting a communication resource in the serving access point

Abstract

An intra-cell handover method in a cellular communication system which utilizes spatial information from an antenna array is disclosed. The spatial information is measured with the antenna array. A determination is then made on whether an intra-cell handover is desirable for a mobile station based upon said measured spatial information. The mobile station is then handed over from a first channel to a second channel when desirable and spatial filters in transceivers for mobile stations using the first and second channels are computed based on the spatial information.

Claims

1. An intra-cell handover method in a cellular communication system having adaptive antenna arrays, comprising the steps of:

measuring spatial information inside a sector with an antenna array;

determining whether an intra-cell handover is desirable for a mobile station based upon said measured spatial information;

handing over said mobile station from a first channel to a second channel within the same sector when desirable; and

computing spatial filters in transceivers for said mobile station and other mobile stations operating on the first and second channels based on the measured spatial information.

2. An intra-cell handover method according to claim 1, wherein the measured spatial information is used to predict an interference situation that would result from various channel allocation decisions.

3. An intra-cell handover method according to claim 2, further comprising the steps of:

measuring power level of said mobile station; and

assigning said mobile station a channel based upon the measured power level and measured spatial information.

4. An intra-cell handover method according to claim 2, further comprising the step of:

computing the relative uplink interference on the mobile station.

5. An intra-cell handover method according to claim 4, further comprising the step of:

computing the relative uplink interference on the mobile station caused by said mobile station.

6. An intra-cell handover method according to claim 2, further comprising the step of:

computing the downlink disturbance to check existing downlinks.

7. An intra-cell handover method according to claim 6, further comprising the step of:

computing the downlink disturbance to check existing downlinks.

8. An intra-cell handover method according to claim 2, wherein said second channel is selected using said computed information.

9. An intra-cell handover method in a cellular communication system having adaptive antenna arrays, comprising the steps of:

measuring spatial information inside a sector with an antenna array;

determining whether an intra-cell handover is desirable for a mobile station based upon said measured spatial information;

handing over said mobile station from a first channel to a second channel within the same sector when desirable; and

computing spatial filters in transceivers for mobile stations using the first channel based on the measured spatial information.

10. An intra-cell handover method according to claim 9, wherein the measured spatial information is used to predict an interference situation that would result from various channel allocation decisions.

11. An intra-cell handover method according to claim 10, further comprising the steps of:

measuring power level of said mobile station; and

assigning said mobile station a channel based upon the measured power level and measured spatial information.

12. An intra-cell handover method according to claim 10, further comprising the step of:

computing the relative uplink interference on other mobile station.

13. An intra-cell handover method according to claim 12, further comprising the step of:

computing the relative uplink interference on other mobile stations caused by said mobile station.

14. An intra-cell handover method according to claim 13, further comprising the step of:

computing the downlink disturbance to check existing downlinks.

15. An intra-cell handover method according to claim 10, further comprising the step of:

computing the downlink disturbance to check existing downlinks.

16. An intra-cell handover method according to claim 10, wherein said second channel is selected using said computed information.

17. An intra-cell handover method in a cellular communication system having adaptive antenna arrays, comprising the steps of:

determining whether an intra-cell handover is necessary;

measuring the power level of a mobile station which needs to be handed off;

assigning said mobile station to a channel based upon said measured power level;

computing the relative uplink disturbance on the mobile station;

computing the relative uplink disturbance on other mobiles from said mobile station;

computing the downlink disturbance to check existing downlinks;

selecting a best channel using said computed information; and

modifying spatial filters of all transceivers using the selected channel and the old channel according to new disturbance situation.

18. An intra-cell handover method according to claim 17, wherein said downlink disturbance is computed using measurements from said mobile station.

19. An intra-cell handover method according to claim 17, wherein scalar quality measurements are used when determining whether the handover is necessary.

20. An intra-cell handover method according to claim 17, wherein a handover is performed when two mobile stations using the same channel move too close to each other.

21. An intra-cell handover method according to claim 17, wherein said uplink disturbance is measured at a base station.