Method of determining a symbol transmission format in a transmission system and system

• US 6,314,113 B1
• Filed: 05/21/1998
• Issued: 11/06/2001
• Est. Priority Date: 05/27/1997
• Status: Expired due to Term

• Current Assignee: Saturn Licensing LLC (Sony Group Corp.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Guémas, Philippe
• Primary Examiner(s): Olms, Douglas
• Assistant Examiner(s): Pizarro, Ricardo M.
• Application Number:
  US09/083,696
• Time in Patent Office: 1,265 Days
• Field of Search: 370/480, 370/280, 370/281, 370/347, 370/209, 370/503, 370/203, 370/330, 370/210, 370/206, 370/208, 370/204, 375/259, 375/200, 375/343, 375/146, 375/340, 375/219, 375/215, 375/344, 342/380, 704/226, 348/478
• US Class Current: 370/480
• CPC Class Codes: H04L 27/0012 arrangements for identifying the type of modulation
• CPC Class Codes: H04L 27/2662 Symbol synchronisation
• CPC Class Codes: H04L 27/2666 Acquisition of further OFDM parameters, e.g. bandwidth, subcarrier spacing, or guard interval length
• CPC Class Codes: H04L 27/2678 using cyclostationarities, e.g. cyclic prefix or postfix

Abstract

A method and apparatus for determining the transmission format of complex symbols in a received signal which is formatted in complex symbol blocks. Each block has a first occurrence (GI_k) of a sequence of complex symbols and second occurrence (gI_k) of the same sequence of complex symbols. A correlation between the first and second occurrences is effected by means of acquisition and correlation time windows, the transmission format being determined by searching for maximum correlation between the first complex symbol sequence and the second complex symbol sequence via synchronization of the windows with the received signal so that the windows select the first occurrence and the second occurrence of complex symbols, respectively. Particularly useful in a digital transmission system employing Orthogonal Frequency Division Multiplexing (OFDM).

Claims

1. A method of determining a transmission format for complex symbols in a signal formatted in complex symbol blocks, each block having a first occurrence of a group of complex symbols and a second occurrence of the same group of complex symbols, the two occurrences having a like duration, the method effecting a correlation between the first occurrence and the second occurrence for determining characteristic features of the transmission format, characterized in that the method comprises the following steps:

storing a first sequence of complex symbols taken from a received signal via an acquisition time window which has a longer duration than the duration of the occurrences of complex symbols,

correlating the first sequence of complex symbols with a second sequence of complex symbols selected at another moment in the received signal, via a correlation time window which has a duration equal to that of the acquisition time window, and

determining characteristics of the transmission format by searching for maximum correlation between the first and the second sequences of complex symbols by synchronizing the acquisition window with the received signal and by positioning the acquisition time window and the correlation time window relative to each other in time, the maximum correlation appearing when the first and second sequences of complex symbols include said first and second occurrences, respectively.

2. The method as claimed in claim 1, the signal being an orthogonal frequency-division multiplexing (OFDM) signal, characterized in that the method determines a number of orthogonal frequencies included in at least one transmission format of the OFDM signal.

3. A transmission system for transmitting an orthogonal frequency-division multiplexing (OFDM) signal, the system comprising:

transmission means for transmitting said signal formatted in blocks of complex symbols in accordance with a transmission format, each block comprising a first occurrence of a group of complex symbols and a second occurrence of the same group of complex symbols, the two occurrences having a like duration; and

receiving means comprising means for receiving said signal and correlation means for determining a correlation between the first occurrence and the second occurrence to determine characteristic features of the transmission format;

characterized in that the correlation means comprises;

means for selecting and storing a first sequence of complex symbols selected in the received signal via an acquisition time window which has a duration that is longer than the duration of the occurrences of complex symbols,

means for selecting a second sequence of complex symbols which is selected at another moment in the received signal via a correlation time window which has a duration equal to that of the acquisition time window, the correlation means effecting the correlation between the first sequence and the second sequence of complex symbols, and

means for determining the characteristic features of the transmission format by searching for maximum correlation between the first sequence and the second sequence of complex symbols by synchronizing the acquisition window with the received signal and by positioning the acquisition time window and correlation time window with respect to each other in time, the maximum correlation occurring when the first and the second sequence of complex symbols include said first and second occurrences, respectively.

4. The system as claimed in claim 3, characterized in that the receiving means comprises various channels running in parallel and permitting the determination of various transmission formats.

5. The system as claimed in claim 4, characterized in that the channels operate simultaneously.

6. A receiver for receiving an orthogonal frequency-division multiplexing (OFDM) signal, the signal being formatted in blocks of complex symbols which are in conformity with a transmission format, each block having a first occurrence of a group of complex symbols and a second occurrence of the same group of complex symbols, the two occurrences having a like duration, and the receiver comprising means for receiving said signal and correlation means for determining a correlation between the first occurrence and the second occurrence to determine characteristic features of the transmission format for detecting the received signal;

characterized in that the correlation means comprises;

means for selecting and storing a first sequence of complex symbols selected in the received signal via an acquisition time window which has a duration that is longer than the duration of the occurrences of complex symbols,

means for selecting a second sequence of complex symbols which is selected at another moment in the received signal via a correlation time window which has a duration equal to that of the acquisition time window, the correlation means effecting the correlation between the first sequence and the second sequence of complex symbols, and

means for determining the characteristic features of the transmission format by searching for maximum correlation between the first sequence and the second sequence of complex symbols by synchronizing the acquisition window with the received signal and by positioning the windows with respect to each other in time, the maximum correlation occurring when the first and the second sequence of complex symbols include said first and second occurrences, respectively.

7. The receiver as claimed in claim 6, characterized in that the receiving means comprises various channels running in parallel and permitting the determination of various transmission formats.

8. The receiver as claimed in claim 7, characterized in that the channels operate simultaneously.