Methods and apparatus for multi-carrier communications with variable channel bandwidth

CAFC
  • US 7,787,431 B2
  • Filed: 04/29/2005
  • Issued: 08/31/2010
  • Est. Priority Date: 05/01/2004
  • Status: Active Grant
First Claim
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1. In a variable bandwidth wireless communication system communicating under multiple different communication schemes that each have a different bandwidth, a process performed by a base station of generating an information bearing signal for wireless transmission, the process comprising:

  • utilizing by the base station a number of subcarriers to construct a variable bandwidth wireless channel;

    utilizing by the base station groups of subcarriers, wherein each group includes a plurality of subcarriers;

    maintaining a fixed spacing between adjacent subcarriers;

    adding or subtracting, by the base station, groups of subcarriers to scale the variable bandwidth wireless channel and achieve an operating channel bandwidth; and

    wherein a core-band, including a plurality of subcarrier groups, substantially centered at an operating center frequency of the different communication schemes, is utilized by the base station as a broadcast channel carrying radio control and operation signalling, where the core-band is substantially not wider than a smallest possible operating channel bandwidth of the system; and

    wherein the information bearing signal has a primary preamble sufficient for basic radio operation and wherein;

    the primary preamble is a direct sequence in the time domain with a frequency content confined within the core-band, or is an orthogonal frequency-divisional multiplexing (OFDM) symbol corresponding to a particular frequency pattern within the core-band; and

    wherein properties of the primary preamble comprise;

    an autocorrelation having a large correlation peak with respect to sidelobes;

    a cross-correlation with other primary preambles having a small cross-correlation coefficient with respect to power of other primary preambles; and

    a small peak-to-average ratio; and

    wherein a large number of primary preamble sequences exhibit the properties.

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