Patent ID: 6473449
Filing Date: 2002-10-29
Classification: H04B,H04J,H04W

Abstract:
A method of transmitting data through a common radio communications channel forming a wireless connection between any two data devices of a local area network comprising a plurality of such data devices, wherein each data device (i) uses the same direct-sequence spread spectrum (DSSS) code of a known chip width and (ii) uses spread spectrum processing gain so as to suppress unknown interference signals and unknown multipath signals, the method comprising the following:(A) providing data as a sequence of digital waveform symbols with said DSSS code and with phase rotations of differential quadrature phase shift keying (DQPSK), wherein each digital waveform symbol (a) represents N data bits and (b) is selected from a set of at least 2N possible digital waveform symbols, wherein at least some of the digital waveform symbols are orthogonal to one another; wherein (i) each digital waveform symbol of the set is unique from the others, (ii) the symbol uniqueness is determined by a unique pulse structure, (iii) the shortest pulse width of any of the digital waveform symbols in the set of digital waveform symbols defines a symbol modulation pulse width; and (iv) the DQPSK relates to the phase shift between each pair of sequentially neighboring digital waveform symbols in said sequence; (B) modulating a carrier signal as a function of the digital waveform symbols with said DSSS code and with the DQPSK phase rotations so as to produce a modulated signal; and (C) amplifying and transmitting a radio signal as a function of the modulated signal; wherein the known chip width of said DSSS code is equal to the symbol modulation pulse width of the set of digital waveform symbols in the absence of the DSSS code.