Signal detection in a direct-sequence spread spectrum transmission system

• US 6,795,490 B2
• Filed: 04/17/2002
• Issued: 09/21/2004
• Est. Priority Date: 04/17/2002
• Status: Expired due to Term

• Current Assignee: InterDigital Madison Patent Holdings (InterDigital, Inc.)
• Original Assignee: Thomson Licensing SA (Vantiva SA)
• Inventors: Belotserkovsky, Maxim B.
• Primary Examiner(s): Fan, Chieh M.
• Application Number:
  US10/124,255
• Publication Number:
  US 20030198286A1
• Time in Patent Office: 888 Days
• Field of Search: 375/130, 375/140, 375/141, 375/142, 375/143, 375/145, 375/147, 375/149, 375/150, 375/152, 375/342, 375/354, 375/364, 375/365, 375/366, 375/367, 375/368, 375/343, 370/320, 370/335, 370/342, 370/503, 370/509
• US Class Current: 375/150
• CPC Class Codes: H04B 1/708 Parallel implementation
• CPC Class Codes: H04B 1/7097 Interference-related aspects

Abstract

A receiver (10) achieves more reliable detection of signals transmitted by Direct Sequence Spread Spectrum Transmission by correlating received signals with a separate of N symbol patterns via N detector stages (18₁-18_N). A maximum peak power detecting mechanism (24₁-24_N, 26₁-26_N and 28) detects which of the N correlated symbol patterns has a maximum peak power, as well as the identity of each of the N patterns actually received and an index of the peak power in each symbol. A computing mechanism (30, 32 and 34) computes a running power average of the received signals, while a ratio computing stage (36) computes the ratio of the largest peak power of the N correlated symbol patterns to the running power average. A comparator stage (38 and 40) compares the ratio to a threshold value to determine a first symbol in the received signals. From knowledge of the first symbol received, the identity of that symbol, and the true burst location of the received symbol relative to a receiver time base can be determined, thus providing more reliable signal detection.

Claims

1. A method for improved detection of received signals transmitted by Direct Sequence Spread Spectrum Transmission, comprising the steps of:

continuously correlating the received signals with each of N known symbol patterns, where N is an integer, to yield N correlated symbol patterns;

determining which of the N correlated symbol patterns has a largest peak power;

determining a running power average of the received signals;

computing a ratio of the largest peak power of the N correlated symbol patterns to the running power average; and

comparing the ratio to a threshold value to determine a first symbol in the received signals, an identity of the first symbol, and a true burst location of the first symbol relative to a receiver time base.

2. The method according to claim 1 wherein the determining steps are performed simultaneously.

3. The method according to claim 1 wherein step of determining which of the N correlated symbol patterns has the largest peak power comprises the steps of:

(a) determining a power value for each of the N correlated symbol patterns;

(b) detecting a peak within the power value for each of the N correlated symbol patterns; and

(c) determining from the peak power values for the N correlated symbol patterns which symbol pattern has a maximum value as well an identity of each of the N patterns actually received and an index of the peak power within each symbol in each symbol pattern.

4. The method according to claim 1 wherein the identity of the first symbol corresponds to the one of the N correlated symbol patterns having the largest peak power.

5. The method according to claim 1 wherein the threshold value is determined from knowledge of the sequence of the received signals.

6. Apparatus for improved detection of signals transmitted by Direct Sequence Spread Spectrum Transmission, comprising:

N detector stages, each correlating received signals with a separate one of N separate known symbol patterns where N is an integer, to yield N correlated symbol patterns;

a maximum peak power detecting mechanism for;

(a) detecting which of the N correlated symbol patterns output by the N detector stages has a maximum peak power, (b) determining an identity of each of the N symbol patterns actually received and (c) establishing an index of the peak power within the symbol in each received symbol pattern;

a first computing mechanism for computing a running power average of the received signals;

a second computing mechanism for computing a ratio of the maximum peak power, as established by the maximum peak power detecting mechanism, to the running power average;

as established by first computing mechanism, and

a comparator stage for comparing the ratio to a threshold value to determine a first symbol in the received signals, the first symbol having an identity corresponding to the one of the N correlated symbol patterns having the largest peak power, and the first symbol having a true burst location relative to a receiver time base corresponding to the index of the peak power within that symbol.

7. The apparatus according to claim 6 wherein each of the N detector stages comprises:

a pattern generator for generating a separate one of N possible known symbol patterns; and

a pattern correlator for correlating the received signals with the separate one of the N known symbol patterns produced by the pattern generator.

8. The apparatus according to claim 6 wherein the maximum peak power detecting mechanism comprises:

N power monitors, each measuring the power of a corresponding one of the N correlated symbol patterns;

N peak detectors, each detecting a peak in the power measured by a corresponding one of the power monitors; and

a maximum peak power detecting stage for determining which of the N correlated symbol patterns has a peak power, as detected by a separate one of the peak detectors as well the identity of each of the N patterns actually received and the index of the peak power within each symbol in each symbol pattern.

9. The apparatus according to claim 6 wherein the first computing mechanism comprises:

a power monitor for measuring the power of the received signals;

a peak detector for detecting a peak in the power measured by the power monitor; and

a computing stage responsive to the peak in the power measured by the peak detector for computing a running power of the peaks measured by the peak detector.