Method and apparatus for start of frame delimiter detection

• US 8,831,070 B2
• Filed: 06/21/2011
• Issued: 09/09/2014
• Est. Priority Date: 06/24/2010
• Status: Active Grant

• Current Assignee: Stichting Imec Nederland
• Original Assignee: Stichting Imec Nederland
• Inventors: Huang, Li, Busze, Ben, Dolmans, Guido
• Primary Examiner(s): Fotakis, Aristocratis
• Application Number:
  US13/703,847
• Publication Number:
  US 20130114645A1
• Time in Patent Office: 1,176 Days
• Field of Search: 375/147, 375/150, 375/365, 370/513, 370/514, 370/515, 370/350, 370/509
• US Class Current: 375/147
• CPC Class Codes: H04B 1/7083 Cell search, e.g. using a three-step approach
• CPC Class Codes: H04L 45/74 Address processing for routing
• CPC Class Codes: H04L 7/042 Detectors therefor, e.g. correlators, state machines digital correlators in general G06F17/15

Abstract

The present disclosure is related to detecting a start frame delimiter. A received data packet is correlated with a known sequence, which provides a first correlation result. The received data packet is correlated with a predefined sequence, which yields at least a second correlation result. The data packet comprises at least a preamble portion and a header portion, whereby the preamble portion comprises the start frame delimiter. The predefined sequence is determined according to the preamble pattern. The method further comprises comparing the first correlation result with the second correlation result and comparing the first correlation result with a given threshold. The process of correlating will be continued until two criteria are met: the first correlation result is larger than the threshold and larger than the at least second correlation result. Only then it is decided that the start of frame delimiter pattern has been detected.

Claims

1. A method for detecting a known start of frame delimiter pattern in a received stream of samples of a data packet, said data packet comprising at least a preamble portion and a header portion, said preamble portion preceding said header portion and containing said start of frame delimiter pattern, the method comprising the steps of:

correlating a portion of said received stream of samples of said data packet with a first sequence corresponding to said start of frame delimiter pattern, thereby obtaining a first correlation result;

comparing said first correlation result with a given threshold;

correlating said portion of said received stream of samples with a second sequence, said second sequence derived from a pattern present in said preamble portion and different from said first sequence, thereby obtaining a second correlation result;

comparing said first correlation result with said second correlation result;

deciding that said start frame delimiter pattern has been detected, if said first correlation result is larger than said given threshold and larger than said second correlation result;

otherwise, repeating the previous steps with a further portion of said first and second sequence.

2. The method of claim 1, comprising a step of determining said second sequence.

3. The method of claim 1, comprising at least one further step of correlating with a further sequence, said further sequence derived from a further pattern present in said preamble portion and different from said start frame delimiter pattern and said second sequence, thereby obtaining a further correlation result, and comparing said first correlation result with said further correlation result, whereby said first threshold should be larger than said further correlation result to detect said start of frame delimiter pattern.

4. The method of claim 1, wherein said given threshold is derived from a received noise power estimation.

5. The method of claim 1, wherein said second sequence has the same length as said first sequence.

6. The method of claim 5, wherein said second sequence is a pattern in said preamble portion that yields the largest correlation value when correlated with said start of frame delimiter pattern, leaving aside said first sequence.

7. A method for performing data acquisition on a stream of samples of data packets received in a receiver device, said method comprising the steps of:

detecting in said receiver device a received data packet by correlating said stream of samples with a random sequence until a correlation result is obtained larger than or equal to a predetermined noise level threshold;

estimating a sampling position for a code symbol of said random sequence and estimating a position for forming a bit by combining one or more code symbols; and

detecting a start of frame delimiter pattern with the method of claim 1.

8. The method of claim 7, comprising the step of performing a noise power estimation and computing said predetermined noise level threshold from said noise power estimation.

9. The method of claim 7, wherein said random sequence contains one code symbol.

10. The method of claim 7, wherein said random sequence is a pseudo-noise sequence containing a plurality of code symbols, wherein said receiver device is a direct sequence spread spectrum receiver.

11. A device for detecting a known start of frame delimiter pattern, said device comprising:

receiver means for receiving a stream of samples of a data packet, said data packet comprising at least a preamble portion and a header portion, said preamble portion preceding said header portion and containing said start of frame delimiter pattern;

first correlator means for correlating a portion of said received stream of samples of said data packet with a first sequence corresponding to said start of frame delimiter pattern, thereby obtaining a first correlation result;

first comparing means for comparing said first correlation result with a given threshold;

second correlator means for correlating said portion of said received stream of samples with a second sequence, said second sequence derived from a pattern present in said preamble portion and different from said first sequence, thereby obtaining a second correlation result;

second comparing means for comparing said first correlation result with said second correlation result; and

combining means for combining outcomes of said first comparing means and said second comparing means.

12. The device of claim 11, wherein said first and second correlator means are sliding correlators.

13. The device of claim 11, wherein each of said first and second correlator means comprise a finite impulse response filter.

14. A device for detecting a known start of frame delimiter pattern, the device comprising:

a receiver configured to receive a stream of samples of a data packet, said data packet comprising at least a preamble portion and a header portion, said preamble portion preceding said header portion and containing said start of frame delimiter pattern;

a first correlation module configured to correlate a portion of said received stream of samples of said data packet with a first sequence corresponding to said start of frame delimiter pattern, thereby obtaining a first correlation result;

a first comparator configured to compare said first correlation result with a given threshold;

a second correlation module configured to correlate said portion of said received stream of samples with a second sequence, said second sequence derived from a pattern present in said preamble portion and different from said first sequence, thereby obtaining a second correlation result;

a second comparator configured to compare said first correlation result with said second correlation result; and

a logic and-unit configured to combine respective outcomes of said first comparator and said second comparator.

15. The device of claim 14, wherein at least some parts of the first correlation module and the second correlation module are shared between the first correlation module and the second correlation module.

16. The device of claim 15, wherein the at least some parts are selected from the group consisting of delay elements and storage elements.

17. The device of claim 14, wherein each of the first correlation module and the second correlation module comprise a finite impulse response filter.

18. The device of claim 14, wherein the first correlation module and the second correlation module are sliding correlators.