Abstract: A method and apparatus for obtaining a channel estimate and a baud frequency offset estimate for a communications channel in a communications system. The communications system has a transmitter for transmitting to a receiver over the communications channel signals representing data appended to a preamble signal. The preamble signal is provided as a periodic plurality of preamble sequences, each preamble sequence being generated in accordance with: 1 32 ? ? k = 0 15 ? ? ? b k ? b mod ? ( k + n , 16 ) * = { 1 , n = 0 0 , n ? 0 . A signal representing the periodic plurality of preamble sequences is sent by a transmitter over the communications channel to a receiver and is received at the receiver as a received signal.

Abstract: A method and apparatus for obtaining a channel estimate and a baud frequency offset estimate for a communications channel in a communications system. The communications system has a transmitter for transmitting to a receiver over the communications channel signals representing data appended to a preamble signal. The preamble signal is provided as a periodic plurality of preamble sequences, each preamble sequence being generated in accordance with: 1 1 32 ⁢ ∑ k = 0 15 ⁢   ⁢ b k ⁢ b mod ⁡ ( k + n , 16 ) * = { 1 , n = 0 0 , n ≠ 0 .

Abstract: A method of determining a start of a transmitted frame at a receiver on a frame-based communications network. A preamble format for the transmitted frame is provided wherein a plurality of identical copies of a preamble symbol sequence are transmitted sequentially. A received transmitted frame is filtered using filter coefficients matched to the preamble symbol sequence to provide a correlation sequence. A squared-magnitude of the correlation sequence is computed. The squared-magnitude of the correlation sequence is low-pass filtered to provide a low-pass filtered correlation signal low-pass filtered signal. The low-pass filtered correlation signal is delayed to provide a delayed low-pass filtered correlation signal. The delayed low-pass filtered correlation signal is multiplied by a first fixed predetermined threshold to provide a multiplied correlation signal. The multiplied correlation signal is compared with the low-pass filtered correlation signal to provide a correlation difference indicator.

Abstract: A method and apparatus for obtaining a channel estimate and a baud frequency offset estimate for a communications channel in a communications system. The communications system has a transmitter for transmitting to a receiver over the communications channel signals representing data appended to a preamble signal.

Abstract: A method of determining an end of a transmitted frame at a receiver on a frame-based communications network. An end of frame format for the transmitted frame is provided having an end of frame plurality of symbols. A received transmitted frame is filtered using filter coefficients matched to the end of frame plurality of symbols to provide a correlation sequence low-pass filtered signal. A squared magnitude of the correlation sequence is computed. The squared magnitude of the correlation sequence is low-pass filtered to provide a low-pass filtered correlation signal. The low-pass filtered correlation signal is delayed to provide a delayed low-pass filtered correlation signal. The delayed low-pass filtered correlation signal is multiplied by a fixed predetermined threshold to provide a multiplied correlation signal. The multiplied correlation signal is compared with the low-pass filtered correlation signal to provide a match/no match comparison indicative of the possible end of a transmitted frame.

Abstract: A method and signal therfor embodied in a carrier wave for sending information from transmit stations to receive stations over a transmission medium of a frame-based communications network. The information is sent in transmit frames having a frame format comprising a fixed rate header, followed by a variable rate payload, followed by a fixed rate trailer. The fixed rate header includes a preamble. The preamble has a repetition of four symbol sequences for facilitating power estimation, gain control, baud frequency offset estimation, equalizer training, carrier sensing and collision detection. The preamble also includes a frame control field.

Abstract: A method of determining a collision between two or more transmitting stations at one of the transmitting stations on a frame-based communications network. A transmitted frame header includes a cyclic preamble wherein identical copies of a preamble symbol sequence are transmitted sequentially. A collision is declared if an estimate of error power in second and third copies of the preamble minus an estimate of error power in third and fourth copies of the preamble exceeds a first threshold, or a maximum value of the norm of each term of a source field error vector minus a greater of the estimate of the error power in the second and third copies of the cyclic preamble and the estimate of the error power in the third and fourth copies of the preamble exceeds a second threshold.

Abstract: A direct digital synthesizer (DDS) for generating a waveform generates a sequence of n-bit phase signals representing phase of the waveform, wherein n is an integer greater than zero. Each n-bit phase signal comprises a phase estimate signal and a phase error signal. The phase estimate signal comprises a most-significant m bits of the n-bit quantity (0 <m<n). The phase-error signal comprises a least-significant n-m bits of the n-bit quantity. The DDS further has a sigma-delta modulator for generating a compensation signal from the phase error signals. The phase estimate signal is added to the compensation signal to produce a compensated phase signal, which may be used to address a look-up table having waveform samples stored in correspondence with look-up table addresses. A digital to analog converter may be coupled to receive waveform samples from the look-up table in order to generate a corresponding analog waveform signal.