Method and apparatus for configuring a RAKE receiver

• US 7,382,821 B2
• Filed: 01/24/2007
• Issued: 06/03/2008
• Est. Priority Date: 12/04/1998
• Status: Expired due to Fees

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Palenius, Torgny, Atarius, Roozbeh, Eriksson, Håkan B., Gustafsson, Kjell B., Carlsson, Torsten J., Östberg, Christer
• Primary Examiner(s): Lugo; David B.
• Application Number:
  US11/626,728
• Publication Number:
  US 20070116103A1
• Time in Patent Office: 496 Days
• Field of Search: 375147-150, 375/152, 375/316, 375142-144
• US Class Current: 375/148
• CPC Class Codes: H04B 1/7093 Matched filter type
• CPC Class Codes: H04B 1/7115 Constructive combining of multi-path signals, i.e. RAKE receivers

Abstract

A searcher uses an input signal, and for example, a matched filter to generate a first set of candidate paths. A selector uses the input signal and the first set of candidate paths to generate a second set of paths. The second set of paths is used to configure the fingers of a RAKE receiver. According to one aspect of the invention, the first set of candidate paths contains M paths, and the second stage uses M correlators to generate a set of M correlation values. The second stage uses the M correlation values to select N paths that are used to configure the N fingers of the RAKE receiver. According to another aspect of the invention, the first set of candidate paths contains M paths, and the second stage uses a multiple of M correlators to track the M paths and generate a set of M estimates. The second stage uses the M estimates to select N paths that are used to configure the N fingers of the RAKE receiver. According to another aspect of the invention, the selector can generate new sets of N paths while the searcher is either active or inactive. The receiver can use a quality signal or a counter to notify the searcher and/or the selector to generate new sets of paths. The selector decreases the need to continuously run the matched filter. The receiver can re-configure the fingers without having to search for new paths. The receiver can also find paths that are uncorrelated and less susceptible to fading.

Claims

1. A RAKE receiver with N fingers, the RAKE receiver comprising:

a first stage, the first stage configured to use an input signal to find a set of more than N paths;

a second stage, the second stage configured to use the first set of more than N paths, the input signal and a quality signal from the RAKE receiver to generate a set of N paths, the second stage generates the set of N paths more frequently than the first stage generates the set of more than N paths; and

a third stage, the third stage configured to use the set of N paths to configure the N fingers of the RAKE receiver.

2. A RAKE receiver as described in claim 1, the first stage configured to use an input signal to find a set of M paths, the second stage comprising M correlators, the second stage configured to use the outputs of the M correlators to generate the set of N paths.

3. A RAKE receiver as described in claim 1, the first stage configured to use an input signal to find a set of M paths, the second stage comprising 3*M correlators, wherein 3 correlators are assigned to each of the M paths, and the second stage configured to use the 3*M correlators to generate M estimates.

4. A RAKE receiver as described in claim 3, the second stage configured to use the M estimates to generate a second set of paths.

5. A RAKE receiver as described in claim 1, the second stage configured to use the input signal to generate a new set of N paths.

6. A RAKE receiver as described in claim 5, the second stage configured to select the new set of N paths from the first set of more than N paths.

7. A RAKE receiver as described in claim 5, the second stage configured to derive the new set of N paths from the first set of more than N paths.

8. A RAKE receiver as described in claim 1, the first stage configured to use an output of a matched filter to generate the first set of more than N paths.

9. A RAKE receiver as described in claim 8, the second stage configured to generate a new set of N paths while the first stage is active generating a new set of more than N paths.

10. A RAKE receiver as described in claim 1, the apparatus further comprising a quality signal, the first stage configured to generate a new set of more than N paths when the quality signal is less than a threshold value.

11. A RAKE receiver as described in claim 10, the third stage configured to use paths from the second stage until the first stage generates the new set of more than N paths.

12. An apparatus as described in claim 1, the apparatus further comprising a counter, the first stage configured to generate a new set of more than N paths when the value of the counter is greater than a pre-set value.