Method and apparatus for a synchronization channel in an OFDMA system

• US 7,706,249 B2
• Filed: 02/08/2006
• Issued: 04/27/2010
• Est. Priority Date: 02/08/2006
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Baum, Kevin L., Akita, Hidenori, Love, Robert T., Fukuta, Masaya, Nangia, Vijay, Stewart, Kenneth A., Classon, Brian K., Hayashi, Hiroshi
• Primary Examiner(s): Rao; Seema S
• Assistant Examiner(s): HUYNH, KHOA B
• Application Number:
  US11/351,304
• Publication Number:
  US 20070183306A1
• Time in Patent Office: 1,539 Days
• Field of Search: 370/203, 370/208, 370/464, 370/498, 370/503, 370/310, 370/328, 370/345, 370/350, 370/329, 370/336, 370/337, 370/342, 455/39, 455/500, 455/507, 455/517, 455/524, 455/525, 455/67.11, 455/67.13, 455/130, 455/150.1, 455/151.1, 455/179.1, 455/403, 455/422.1, 455/436, 455/437, 455/442, 375/130, 375/140, 375/141, 375/145, 375/259, 375/260, 375/267, 375/295, 375/299, 375/316, 375/346, 375/347
• US Class Current: 370/208
• CPC Class Codes: H04J 11/0073 Acquisition of primary synchronisation channel, e.g. detection of cell-ID within cell-ID group
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 27/2655 Synchronisation arrangements
• CPC Class Codes: H04L 27/2656 Frame synchronisation, e.g. packet synchronisation, time division duplex [TDD] switching point detection or subframe synchronisation
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/005 of common pilots, i.e. pilots destined for multiple users or terminals
• CPC Class Codes: H04L 5/0064 Rate requirement of the data, e.g. scalable bandwidth, data priority

Abstract

A method and apparatus is provided for transmitting an orthogonal frequency domain multiple access (OFDMA) signal including a synchronization channel signal transmitted within a localized portion of a bandwidth of the OFDMA signal (818), the synchronization channel signal having predetermined time domain symmetry within the localized portion of the bandwidth (816). The synchronization channel signal enables an initial acquisition and cell search method with low computational load which provides OFDMA symbol timing detection and frequency error detection by differential processing of sequence elements of the synchronization channel signal (1112) and frame boundary detection and cell specific information detection (1114) in an OFDMA system supporting multiple system bandwidths, both synchronized and un-synchronized systems, a large cell index and an OFDMA symbol structure with both short and long cyclic prefix length.

Claims

1. A method for use in a base station in a wireless communication system wherein the base station has cell identification information associated therewith, the cell identification information associated with the base station comprising first and second partial cell identification information stored in a storage device thereof, the base station further including a synchronization channel generator for generating a synchronization channel signal, and transmitter circuitry for transmitting an orthogonal frequency domain multiple access (OFDMA) signal, the method comprising the steps of:

the synchronization channel generator generating the synchronization channel signal comprising at least first and second synchronization channel signals, the first and second synchronization channel signals comprising respective first and second sets of one or more individual sequence elements, and wherein the first set of one or more individual sequence elements is generated based on a general chirp like (GCL) sequence with a sequence index of the GCL sequence defined in response to the first partial cell identification information stored in the storage device of the base station, and wherein the second set of one or more individual sequence elements is generated based on a cyclically shifted maximal length binary sequence with an amount of cyclic shift of the maximal length binary sequence defined in response to the second partial cell identification information stored in the storage device of the base station; and

the transmitter circuitry transmitting the OFDMA signal including the synchronization channel signal.

2. The method in accordance with claim 1 wherein the first partial cell identification information comprises cell identification information identifying the base station within a cell group comprising one or more base stations including the base station transmitting the OFDMA signal, and wherein the second partial cell identification information comprises cell group identification information identifying the cell group.

3. The method in accordance with claim 1 wherein the OFDMA signal comprises a plurality of subcarriers, and wherein the step of transmitting the OFDMA signal comprises the step of mapping at least a portion of the first and second sets of one or more individual sequence elements to every nth subcarrier of at least a portion of the plurality of subcarriers, where n is an integer greater than or equal to two.

4. The method in accordance with claim 1 wherein the step of transmitting the OFDMA signal comprises the step of transmitting the OFDMA signal comprising a plurality of frames, each of the plurality of frames comprising a plurality of subframes, the synchronization channel signal transmitted once every N subframes, wherein N is an integer greater than or equal to ten.

5. The method in accordance with claim 4 wherein the step of transmitting the OFDMA signal comprises the step of transmitting the OFDMA signal wherein the synchronization channel signal is transmitted once every N subframes, wherein N is equal to ten and each subframe has a duration of 0.5 ms and comprises a plurality of OFDMA symbols.

6. The method in accordance with claim 1 wherein the step of generating the OFDMA signal comprises the step of generating the OFDMA signal including the synchronization channel signal comprising the first and second sets of one or more individual sequence elements, wherein the amount of cyclic shift of the cyclically shifted maximal length binary sequence is derived in response to the second partial cell identification information, the second partial cell identification information comprising cell group identification information identifying a cell group comprising one or more base stations including the base station.

7. A method for use in a wireless communication device including receiver circuitry for receiving and demodulating an orthogonal frequency domain multiple access (OFDMA) signal including a synchronization channel signal and a controller for detecting the synchronization channel signal, the method comprising the steps of:

the receiver circuitry receiving the OFDMA signal including the synchronization channel signal from a base station transmitting the OFDMA signal, the synchronization channel signal comprising a plurality of synchronization channel signal sequence elements, wherein cell identification associated with the base station transmitting the OFDMA signal comprising first and second partial cell identification information;

the controller detecting first and second synchronization channel signals of the synchronization channel signal within the OFDMA signal, the first and second synchronization channel signals comprising respective first and second sets of one or more individual sequence elements, the first set of one or more individual sequence elements based on a generalized chirp like (GCL) sequence and the second set of one or more individual sequence elements based on a cyclically shifted maximal length binary sequence; and

the controller further determining the first partial cell identification information in response to a sequence index of the GCL sequence of the first set of one or more individual sequence elements and determining the second partial cell identification information in response to an amount of cyclic shift of the maximal length binary sequence of the second set of one or more individual sequence elements.

8. The method in accordance with claim 7 wherein the cell identification associated with the base station transmitting the OFDMA signal comprises the first and second partial cell identification information, and wherein the first partial cell identification information comprises cell identification information identifying the base station within a cell group comprising one or more base stations including the base station transmitting the OFDMA signal, and wherein the second partial cell identification information comprises cell group identification information identifying the cell group.

9. The method in accordance with claim 7 wherein the step of determining the first and second partial cell identification information comprises the step of determining the second partial cell identification information in response to the amount of cyclic shift of the cyclically shifted maximal length binary sequence of the second set of one or more individual sequence elements, the second partial cell identification information comprising cell group identification information identifying a cell group comprising one or more base stations including the base station transmitting the OFDMA signal.

10. The method in accordance with claim 7 wherein the OFDMA signal comprises a plurality of subcarriers, and wherein the step of detecting the plurality of synchronization channel signal sequence elements comprises the step of detecting at least a portion of the first and second sets of one or more individual sequence elements mapped to every nth subcarrier of at least a portion of the plurality of subcarriers, where n is an integer greater than or equal to two.

11. The method in accordance with claim 7 wherein the OFDMA signal comprises a plurality of frames, each of the plurality of frames comprising a plurality of subframes, and wherein the step of detecting the first and second sets of one or more individual sequence elements comprises the step of detecting the first and second sets of one or more individual sequence elements within every N subframes of the plurality of subframes, wherein N is an integer greater than or equal to two.

12. The method in accordance with claim 7 wherein the OFDMA signal comprises a plurality of frames, each of the plurality of frames having frame boundaries, and wherein the step of detecting the first and second sets of one or more individual sequence elements comprises the step of detecting the frame boundaries in response to reception of the first and second sets of one or more individual sequence elements.