System and method for estimating interfrequency measurements used for radio network function

• US 6,546,252 B1
• Filed: 12/15/1999
• Issued: 04/08/2003
• Est. Priority Date: 12/18/1998
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Johansson, Lars B, Müller, Walter, Blomberg, Petter, Butovitsch, Peter, Jetzek, Ulrich
• Primary Examiner(s): VO, NGUYEN THANH
• Application Number:
  US09/464,484
• Time in Patent Office: 1,210 Days
• Field of Search: 455/436, 455/437, 455/438, 455/439, 455/443, 455/524, 455/525, 455/62, 455/63, 455/522, 370/331, 370/332
• US Class Current: 455/437
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04B 17/382 for resource allocation, admission control or handover
• CPC Class Codes: H04W 36/06 Reselecting a communication resource in the serving access point
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection

Abstract

Systems and methods for estimating inter-frequency measurements used for radio network functions are disclosed. The systems and methods described allow systems to evaluate the quality of a second frequency by using offset adjusted measurements on a first frequency. By using the described methods, system capacity is increased by providing a “low cost” measurement mechanism for support of handover that substantially balance the load between two or more frequency bands. By using the proposed method, handover can be performed more frequently and the interference within each frequency band can therefore be kept at a more optimal level.

Claims

1. In a cellular system, a method for performing handover, the method comprising the steps of:

determining a transmission quality on a first frequency band;

determining a quality offset;

estimating the transmission quality of a second frequency band based on the quality offset by adding the quality offset to the transmission quality on the first frequency band; and

initiating a handover from the first frequency band to the second frequency band according to the estimated transmission quality of the second frequency band.

2. The method of claim 1, further comprising the step of determining a quality threshold.

3. The method of claim 2, wherein the handover occurs once the transmission quality on the second frequency band exceeds the quality threshold, provided that the quality offset is positive.

4. The cellular system of claim 1, wherein the cellular system comprises at least one cell having at least two logical sectors such that one of the logical sectors is assigned to the first frequency band and the other logical sector is assigned to the second frequency band.

5. The cellular system of claim 1, wherein the quality offset is a function of the ratio of downlink transmission power on the second frequency band compared to downlink transmission power on the first frequency band.

6. The cellular system of claim 5, wherein the quality offset is a function of the ratio of downlink transmission power (DL power) on the second frequency band (f2) and the first frequency band (f1), according to the relation:

7. A quality determining means in a cellular system, comprising,

measurement means for measuring a first transmission quality on a first frequency band;

determining means for determining a quality offset; and

processing means for estimating a second transmission quality on a second frequency band by adding the quality offset to the first transmission quality,

wherein a handover from the first frequency band to the second frequency band is initiated according to the second transmission quality.

8. The quality determining means in the cellular system as in claim 7, wherein the cellular system comprises at least one cell having at least two logical sectors such that one of the logical sectors is assigned to the first frequency band and the other logical sector is assigned to the second frequency band.

9. The quality determining means in the cellular system as in claim 7, wherein the quality offset is a function of the ratio of downlink transmission power on the second frequency band compared to downlink transmission power on the first frequency band.

10. The quality determining means in the cellular system as in claim 9, wherein the quality offset is a function of the ratio of downlink transmission power (DL power) on the second frequency band (f2) and the first frequency band (f1), according to the relation:

11. A control means in a cellular system comprising a quality determining means,

the quality determining means comprising,

measurement means for measuring a first transmission quality on a first frequency band;

determining means for determining a quality offset; and

processing means for estimating a second transmission quality on a second frequency band by adding the quality offset to the first transmission quality,

the control means further comprising means for determining a quality threshold, wherein a handover from the first frequency band to the second frequency band is initiated once the second transmission quality exceeds the quality threshold, provided that the quality offset is positive.

12. The control means of claim 11, wherein the control means is disposed in a switch of a cellular system.

13. The control means of claim 11, wherein the control means is disposed in a mobile station of a cellular system.

14. The control means in the cellular system as in claim 11, wherein the cellular system comprises at least one cell having at least two logical sectors such that one of the logical sectors is assigned to the first frequency band and the other logical sector is assigned to the second frequency band.

15. The control means in the cellular system as in claim 11, wherein the quality offset is a function of the ratio of downlink transmission power on the second frequency band compared to downlink transmission power on the first frequency band.

16. The control means in the cellular system as in claim 15, wherein the quality offset is a function of the ratio of downlink transmission power (DL power) on the second frequency band (f2) and the first frequency band (f1), according to the relation:

17. A cellular system comprising a base transceiver station and a mobile station that transmits signals across a first frequency band to each other, the cellular system measures the transmission quality on the first frequency band, wherein the cellular system determines a quality offset and estimates the transmission quality on the second frequency band by adding the quality offset to the transmission quality on the first frequency band, and wherein a handover from the first frequency band to the second frequency band is initiated according to the estimated transmission quality of the second frequency band.

18. The cellular system of claim 17, wherein the cellular system comprises at least one cell having at least two logical sectors such that one of the logical sectors is assigned to the first frequency band and the other logical sector is assigned to the second frequency band.