CDMA receiver that shares a tracking device among multiple rake branches

• US 6,330,271 B1
• Filed: 10/13/1998
• Issued: 12/11/2001
• Est. Priority Date: 10/13/1998
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Konradsson, Per, Klang, Go̅ran
• Primary Examiner(s): Ghayour, Mohammad H.
• Application Number:
  US09/169,943
• Time in Patent Office: 1,155 Days
• Field of Search: 375/134, 375/147, 375/140, 375/347, 375/130, 370/335, 370/342, 370/441, 455/10, 455/504, 455/526
• US Class Current: 375/134
• CPC Class Codes: H04B 1/7085 using a code tracking loop, e.g. a delay-locked loop
• CPC Class Codes: H04B 1/7113 Determination of path profile
• CPC Class Codes: H04B 1/7115 Constructive combining of multi-path signals, i.e. RAKE receivers
• CPC Class Codes: H04B 1/7117 Selection, re-selection, allocation or re-allocation of paths to fingers, e.g. timing offset control of allocated fingers

Abstract

A CDMA receiver includes a plurality of RAKE branches for despreading the received CDMA signals over a corresponding plurality of paths and a single tracking device that is shared among the plurality of the RAKE branches for tracking the delays of the received CDMA signal over a corresponding path. Similarly, a method for tracking a CDMA signal correlates the received signal with local PN codes using a plurality of RAKE branches and tracks the received signal using a single tracking device that is shared among the plurality of the RAKE branches.

Claims

1. A CDMA receiver for receiving a CDMA signal over a multi-channel, comprising:

a plurality of RAKE branches for despreading the received CDMA signals over a corresponding plurality of paths; and

a tracking device that is selectively coupled to each one of the plurality of RAKE branches for tracking the delays of the received CDMA signal over a corresponding path.

2. The CDMA receiver of claim 1, wherein the tracking device is selectively coupled to the plurality of RAKE branches at a constant rate.

3. The CDMA receiver of claim 1, wherein the tracking device is selectively coupled the plurality of RAKE branches at a dynamic rate that is dependent on channel conditions.

4. The CDMA receiver of claim 3, wherein the dynamic rate is determined based on a measurement of a received power level and a predefined threshold.

5. The CDMA receiver of claim 4, wherein the received power level is measured over one or more symbols.

6. The CDMA receiver of claim 4, wherein the received power level is based on an average value from several symbols.

7. The CDMA receiver of claim 2, wherein the constant rate is based on one of a symbol, slots or frame duration.

8. The CDMA receiver of claim 1, wherein the tracking device is selectivley coupled the plurality of RAKE branches at a semi static rate that is dependent on changed channel statistics.

9. The CDMA receiver of claim 1, wherein the tracking device is an early/late gate (ELG) tracking device.

10. The CDMA receiver of claim 1, wherein the tracking is a tau-dither tracking device.

11. A method for tracking a CDMA signal including the steps of:

despreading a received signal with local PN codes using a plurality of RAKE branches; and

tracking the received signal using a single tracking device that is selectively coupled to each one of the plurality of RAKE branches.

12. The method of claim 11, wherein the tracking device is selectively coupled to one of the plurality of RAKE branches at a selection rate that is dependent upon channel conditions.

13. The method of claim 12, wherein the selection rate is dynamic.

14. The method of claim 12, wherein the selection rate is semi-static.

15. The method of claim 12, wherein the selection rate is static.

16. The method of claim 11, wherein the tracking device is an early/late gate (ELG) tracking device.

17. The method of claim 11, wherein the tracking device is a tau-dither tracking device.