Preambles in OFDMA system
First Claim
1. A method for accessing an orthogonal frequency division multiplexing access (OFDMA) system comprising the steps of:
- a) constructing at least one OFDMA frame having a first preamble and a second preamble, the first preamble having a common synchronization channel comprising common synchronization subcarriers, the common synchronization subcarriers carrying a common sequence, and the second preamble comprising a base station specific preamble;
the first preamble further including other signaling information pertaining to the configuration of the second preamble;
b) assigning said first preamble for use in a plurality of base stations;
c) transmitting said at least one OFDMA frame by at least one of said plurality of base stations;
d) detecting said at least one OFDMA frame at a subscriber station; and
e) performing synchronization at said subscriber station by using the common sequence of the first preamble, and identifying candidate timing synchronization positions using a correlation of the common sequence, and searching for the second preamble using the candidate timing synchronization positions.
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Accused Products
Abstract
The present invention provides a preamble that is inserted into an OFDMA frame and has a common sequence for all the base stations participating in a transmission. The subscriber station performs fine synchronization using the common sequence on the common preamble, and the resulting peaks will provide the locations of candidate base stations. The base station specific search is then performed in the vicinities of those peaks by using base station specific pseudo-noise sequences. With this two stage cell search, the searching window is drastically reduced. The preamble is matched to known values by a respective receiver to decode the signals and permit multiple signals to be transferred from the transmitter to the receiver. The preamble may comprise two parts, Preamble-1 and Preamble-2, which may be used in different systems, including multioutput, multi-input (MIMO) systems.
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Citations
38 Claims
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1. A method for accessing an orthogonal frequency division multiplexing access (OFDMA) system comprising the steps of:
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a) constructing at least one OFDMA frame having a first preamble and a second preamble, the first preamble having a common synchronization channel comprising common synchronization subcarriers, the common synchronization subcarriers carrying a common sequence, and the second preamble comprising a base station specific preamble;
the first preamble further including other signaling information pertaining to the configuration of the second preamble;b) assigning said first preamble for use in a plurality of base stations; c) transmitting said at least one OFDMA frame by at least one of said plurality of base stations; d) detecting said at least one OFDMA frame at a subscriber station; and e) performing synchronization at said subscriber station by using the common sequence of the first preamble, and identifying candidate timing synchronization positions using a correlation of the common sequence, and searching for the second preamble using the candidate timing synchronization positions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A method in an orthogonal frequency division multiplexing access (OFDMA) system comprising the steps of:
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a) constructing at least one OFDMA frame having a first preamble and a second preamble, the first preamble having a common synchronization channel comprising common synchronization subcarriers, the common synchronization subcarriers for carrying a common sequence, and the second preamble comprising a base station specific preamble, the first preamble further including other signaling information pertaining to the configuration of the second preamble; and b) transmitting the at least one OFDMA frame, the at least one OFDMA frame configured such that a subscriber station would be able to perform synchronization using the common sequence of the first preamble, identify candidate timing synchronization positions using a correlation of the common sequence, and search for the second preamble using the candidate timing synchronization positions. - View Dependent Claims (32, 33, 34)
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35. A method in an orthogonal frequency division multiplexing access (OFDMA) system comprising the steps of:
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a) receiving at a subscriber station at least one OFDMA frame, the at least one OFDMA frame having a first preamble and a second preamble, the first preamble having a common synchronization channel comprising common synchronization subcarriers, the common synchronization subcarriers carrying a common sequence, and the second preamble comprising a base station specific preamble, the first preamble further including other signaling information pertaining to the configuration of the second preamble; and b) performing synchronization at said subscriber station by using the common sequence of the first preamble, and identifying candidate timing synchronization positions using a correlation of the common sequence, and searching for the second preamble using the candidate timing synchronization positions. - View Dependent Claims (36, 37, 38)
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Specification