Transmitter and method for digital multi-carrier transmission

Abstract

The present invention relates to a transmitter and method employing a multi-carrier transmission method, especially utilizing real coefficient wavelet filter banks. The transmitter includes a preamble data generator, a modulator, and a ramp processor. The preamble data generator generates preamble bit data, and outputs the preamble data. The modulator modulates the preamble data, generates a plurality of subcarriers, and outputs a composite wave of the time waves of the plurality of subcarriers. Subsequently, the ramp processor performs ramp processing on the composite wave with a certain delay period from a reference position of the composite wave.

1 . A transmitter employing a digital wavelet multi-carrier modulation, said transmitter comprising:
 a preamble data generator that generates preamble bit data and outputs the preamble data;   a modulator that modulates the preamble data, generates a plurality of subcarriers, and outputs a composite wave of time waves of the plurality of subcarriers; and   a ramp processor that performs ramp processing on the composite wave with a predetermined delay from a reference position of the composite wave.   
   
   
       2 . The transmitter according to  claim 1 , wherein said predetermined delay is one symbol interval delay or less from the reference position of the composite wave. 
   
   
       3 . The transmitter according to  claim 1 , wherein said predetermined delay is more than one symbol interval delay from the reference position of the composite wave. 
   
   
       4 . The transmitter according to  claim 1 , wherein the composite wave localizes in time and frequency domain. 
   
   
       5 . A transmitter employing digital wavelet multi-carrier modulation, said transmitter comprising:
 a preamble data generator that generates preamble bit data and outputs the preamble bit data;   a symbol mapper that transforms the preamble bit data to symbol data;   a wavelet transformer that performs a wavelet transform of the symbol data, generates a plurality of subcarriers, and outputs a composite wave of time waves of the plurality of subcarriers; and   a ramp processor that performs ramp processing on the composite wave with a predetermined delay from a reference position of the composite wave.   
   
   
       6 . The transmitter according to  claim 5 , wherein said preamble data generator generates the preamble bit data by giving, for each subcarrier, the same bit value in a series of symbol intervals. 
   
   
       7 . The transmitter according to  claim 5 , wherein said ramp processor performs the ramp processing to the preamble bit data from the first symbol interval having a proper sine wave. 
   
   
       8 . The transmitter according to  claim 5 , wherein said ramp processor performs the ramp processing for one symbol interval or more. 
   
   
       9 . The transmitter according to  claim 8 □C wherein said ramp processor performs the ramp processing to the preamble bit data from the first symbol interval having a proper sine wave. 
   
   
       10 . A transmitter employing digital wavelet multi-carrier modulation, said transmitter comprising:
 a preamble data generator that generates preamble bit data and outputs the preamble bit data;   a symbol mapper that transforms the preamble bit data into symbol data, maps the symbol data into complex coordinates and outputs mapped data;   a serial-to-parallel transformer that transforms the mapped data inputted serially into parallel data;   a complex decomposer that decomposes the parallel data into in-phase component and quadrature component, and outputs the in-phase component and the quadrature component;   a wavelet transformer that comprises M real coefficient wavelet filters which are orthogonal with respect to each other (M being a positive integer) and that receives the in-phase and quadrature component as (2n−1)th and (2n)th inputted data, respectively, performs a wavelet transform of the inputted data, generates a plurality of subcarriers, and outputs a composite wave of time waves of the plurality of subcarriers; and   a ramp processor that performs ramp processing on the composite wave with a predetermined delay from a reference position of the composite wave.   
   
   
       11 . The transmitter according to  claim 10 , wherein said inverse wavelet-transformer further comprises:
 a fast discrete cosine transformer that performs a cosine transform on the inputted data to produce transformed data;   a prototype filter that comprises a real coefficient polyphase filter, an adder, and a multiplier, and that filters the transformed data to produce filtered data;   M up-samplers that perform an up-sampling on the filtered data to produce up-sampled data; and   M−1 delays that delay the up-sampled data by a certain period.   
   
   
       12 . A transmitter employing digital wavelet multi-carrier modulation, said transmitter comprising:
 a preamble data generating means for generating preamble bit data, and for outputting the preamble data;   a modulating means for modulating the preamble data, for generating a plurality of subcarriers, and for outputting a composite wave of the time waves of the plurality of subcarriers; and   a ramp processing means for performing ramp processing on the composite wave with a predetermined delay from a reference position of the composite wave.   
   
   
       13 . A transmitting method employing digital wavelet multi-carrier modulation, said transmitting method comprising:
 generating preamble bit data and outputting the preamble data;   modulating the preamble data, generating a plurality of subcarriers, and outputting a composite wave of the time waves of the plurality of subcarriers; and   performing ramp processing on the composite wave with a predetermined delay from reference position of the composite wave.   
   
   
       14 . The transmitter of  claim 1  wherein the modulator comprises:
 a symbol mapper that transforms the preamble bit data into symbol data and maps the symbol data into M/2 complex coordinates, where M is the number of subcarriers;   a serial-to-parallel transformer that serially receives the mapped symbol data and transforms the mapped symbol data into parallel data;   a complex decomposer that decomposes the parallel data into real and imaginary parts; and   an inverse wavelet transformer comprising M real-coefficient orthogonal wavelet filters that cooperate to inverse wavelet transform both the real and imaginary parts into the composite wave.   
   
   
       15 . The transmitter of  claim 1 , wherein the modulator comprises:
 a symbol mapper that modulates the preamble bit data to produce symbol data and maps the symbol data into M/2 complex coordinates, where M is the number of subcarriers;   a serial-to-parallel transformer that serially receives the mapped symbol data and transforms the mapped symbol data into parallel data; and   an inverse wavelet transformer comprising M real-coefficient orthogonal wavelet filters that cooperate to decompose the parallel data into real and imaginary parts and inverse wavelet transform both the real and imaginary parts into the composite wave.   
   
   
       16 . The transmitter of  claim 1 S, wherein the inverse wavelet transformer comprises:
 a transformer comprising one of a discrete cosine transformer (DCT) and a discrete sine transformer (DST) that DCT or DST transforms the real and imaginary parts to produce transformed data;   up-samplers that each up-sample components of the transformed data after the components of the transformed data are each respectively filtered by a separate one of the M real-coefficient orthogonal wavelet filters; and   a combining device that combines all of the up-sampled components into the composite wave.   
   
   
       17 . The transmitter of  claim 15 , wherein the M real-coefficient orthogonal wavelet filters cooperate as a polyphase filter with an order of 2M. 
   
   
       18 . The transmitter of  claim 15 , wherein the M real-coefficient orthogonal wavelet filters cooperate as a polyphase filter with an order greater than 2M. 
   
   
       19 . The transmitter of  claim 15 , wherein:
 the M real-coefficient orthogonal wavelet filters comprise filter banks of a length four times the symbol length that cooperate as a polyphase filter; and   the coefficient values of the M filter banks are selectively controllable to attenuate spectral components of the composite wave falling within a frequency range by 30 decibels.   
   
   
       20 . The transmitter of  claim 1 , wherein the ramp processing comprises combining the composite wave with a linearly and monotonically increasing waveform to produce a smoothed waveform. 
   
   
       21 . The transmitter of  claim 1 , wherein the ramp processing comprises combining the composite wave with a raised cosine waveform to produce a smoothed waveform. 
   
   
       22 . A transmitter employing a digital wavelet multi-carrier modulation, said transmitter comprising:
 a preamble data generator that generates preamble bit data, and outputs the preamble data;   a symbol mapper that transforms the preamble data to symbol data;   a wavelet transformer that performs a wavelet transform of the symbol data, generates a plurality of subcarriers, and outputs a composite wave of the plurality of subcarriers; and   a ramp processor that performs ramp processing on the composite wave with a predetermined delay.   
   
   
       23 . A transmitter employing a digital wavelet multi-carrier modulation, said transmitter comprising:
 a preamble data generator that generates preamble bit data, and outputs the preamble data;   a symbol mapper that transforms the preamble data to symbol data;   a wavelet transformer that performs a wavelet transform of the symbol data, generates a plurality of subcarriers, and outputs a composite wave of the plurality of subcarriers; and   a ramp processor that performs ramp processing on the composite wave with a predetermined delay.