Radiocommunication employing selected synchronization technique

• US 20020173286A1
• Filed: 04/06/2001
• Published: 11/21/2002
• Est. Priority Date: 04/06/2001
• Status: Abandoned Application

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Lindoff, Bengt, Singvall, Jakob
• Application Number:
  US09/826,967
• Publication Number:
  US 20020173286A1
• Time in Patent Office: Days
• US Class Current: 455/295
• CPC Class Codes: H04L 1/0001 Systems modifying transmission characteristics according to link quality, e.g. power backoff adaptive data allocation for multicarrier modulation H04L5/0044; controlling transmission power for radio systems H04W52/04
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/03006 Arrangements for removing intersymbol interference
• CPC Class Codes: H04L 7/0054 Detection of the synchronisation error by features other than the received signal transition by means of signal transition H04L7/033
• CPC Class Codes: H04L 7/042 Detectors therefor, e.g. correlators, state machines digital correlators in general G06F17/15

Abstract

A method and apparatus for acquiring time synchronization to a received signal are described. First, a burst of data which includes a known sequence is received. This received signal is processed using a plurality of different synchronization techniques. Each synchronization technique can be paired with a corresponding channel estimation technique, which pairing is predetermined to be optimized for particular channel conditions. A processor or model validation unit selects the channel estimate associated with the channel conditions currently being experienced by the radio signal.

Claims

1. A method for synchronizing to a radio signal comprising the steps of:

receiving said radio signal;

determining a first synchronization position for said radio signal using a first synchronization technique;

generating a first channel estimate using said first synchronization position;

determining a second synchronization position for said radio signal using a second synchronization technique, wherein said second synchronization technique is different from said first synchronization technique;

generating a second channel estimate using said second synchronization position; and

selecting one of said first channel estimate and said second channel estimate for use in subsequent processing of said radio signal.

2. The method of claim 1, wherein said step of determining said first synchronization position further comprises the steps of:

correlating said received radio signal to a known sequence to generate a plurality of correlations;

calculating an energy value by summing squared magnitudes of each of said correlations over a predetermined window; and

selecting, as said first synchronization position, a time value which maximizes said energy value.

3. The method of claim 1, wherein said step of determining said second synchronization position further comprises the steps of:

determining a mean position of a correlation function; and

selecting, as said second synchronization position, a time value which corresponds to said mean position.

4. The method of claim 1, wherein said step of selecting further comprises the step of:

selecting said first channel estimate if time dispersion associated with a radio channel over which said radio signal is received is above a threshold;

otherwise, selecting said second channel estimate position.

5. The method of claim 1, further comprising the step of:

using said selected channel estimate to equalize said received signal.

6. The method of claim 1, wherein said radio signal includes a plurality of frames, each of which includes a known sequence.

18. The method of claim 1, wherein said step of selecting further comprises the step of:

selecting a corresponding one of said first synchronization position and said second synchronization position for use in said subsequent processing of said radio signal.

7. A receiver comprising:

means for receiving a radio signal;

means for determining a first synchronization position for said radio signal using a first synchronization technique;

means for generating a first channel estimate using said first synchronization position;

means for determining a second synchronization position for said radio signal using a second synchronization technique, wherein said second synchronization technique is different from said first synchronization technique;

means for generating a second channel estimate using said second synchronization position; and

means for selecting one of said first channel estimate and said second channel estimate for use in subsequent processing of said radio signal.

8. The receiver of claim 7, wherein said means for determining said first synchronization position further comprise:

means for correlating said received radio signal to a known sequence to generate a plurality of correlations;

means for calculating an energy value by summing squared magnitudes of each of said correlations over a predetermined window; and

means for selecting, as said first synchronization position, a time value which maximizes said energy value.

9. The receiver of claim 7, wherein said means for determining said second synchronization position further comprises:

means for determining a mean position of a correlation function; and

means for selecting, as said second synchronization position, a time value which corresponds to said mean position.

10. The receiver of claim 7, wherein said means for selecting further comprises:

means for selecting said first channel estimate if time dispersion associated with a radio channel over which said radio signal is received is above a threshold and, otherwise, selecting said second channel estimate position.

11. The receiver of claim 7, further comprising:

means for using said selected channel estimate to equalize said received signal.

12. The receiver of claim 7, wherein said radio signal includes a plurality of frames, each of which includes a known sequence.

13. The receiver of claim 7, wherein said receiver is disposed in a mobile station.

14. The receiver of claim 7, wherein said receiver is disposed in a base station.

16. The receiver of claim 15, wherein said first synchronization unit further comprises:

a correlator for correlating said baseband radio signal to said synchronization sequence to generate a plurality of correlations;

a summer for summing squared magnitudes of each of said correlations over a predetermined window to generate an energy value; and

a processor for selecting, as a first synchronization position, a time value which maximizes said energy value.

17. The receiver of claim 15, wherein said second synchronization unit further comprises:

a correlator for correlating said baseband signal with said synchronization sequence to generate correlation values; and

a processor for determining a mean position associated with said correlation values and for selecting, as a second synchronization position, a time value which corresponds to said mean position.

19. The receiver of claim 7, wherein said means for selecting further comprises:

means for selecting a corresponding one of said first synchronization position and said second synchronization position for use in said subsequent processing of said radio signal.

15. A receiver comprising:

a downconverter for downconverting a received signal to baseband signal;

a known sequence generator for generating a synchronization sequence;

a first synchronization unit for synchronizing to said baseband signal using a first synchronization technique; and

a second synchronization unit for synchronizing to said baseband signal using a second synchronization technique, wherein said first synchronization technique and said second synchronization technique are different.