Transmitter and receiver for spread-spectrum communication system, and modulation and demodulation methods thereof

A transmitter for a spread-spectrum communication system, said transmitter comprising:

• a modulation control unit configured to determine the number of subchannels for the multiplexing of transmission data and the number of subcarriers for frequency-hopping in each of the subchannels;
• a serial-to-parallel converting unit configured to split the transmission data into subchannel transmission data for as many subchannels as determined by said modulation control unit;
• a plurality of subchannel modulation processing units each configured to receive the corresponding subchannel transmission data for independent modulation processing so as to output a plurality of subcarrier transmission signals, each of said subchannel modulation processing units including
• 1) a frame generation unit configured to construct a frame by inserting a predetermined pilot sequence in the subchannel transmission data
• 2) a data modulation unit configured to subject the subchannel transmission data of a frame structure to a predetermined data modulation process so as to output a modulated signal,
• 3) a time-spreading unit configured to subject the modulated signal to a time-spreading process by multiplying the modulated signal by a predetermined time-spreading code,
• 4) a data hopping unit including at least one multiplier and configured to output a plurality of subcarrier transmission signals corresponding to the respective subcarriers, by receiving the modulated signal subjected to the time-spreading process, generate a predetermined hopping pattern of a predetermined sequence length, and output as the subcarrier transmission signal only the modulated signal carried in a subcarrier designated by the hopping pattern, while maintaining the other subcarrier transmission signals at a zero output level;
• and
• an inverse Fourier transform unit configured to subject the entirety of subcarrier transmission signals output from said data hopping unit of said plurality of subchannel modulation processing units to inverse Fourier transform so as to output transmission signals multiplexed using said plurality of subchannels in which frequency-hopping spectrum-spreading is effected.

A transmitter for a spread-spectrum communication system, said transmitter comprising:

• a modulation control unit configured to determine the number of subchannels for the multiplexing of transmission data and the number of subcarriers for frequency-hopping in each of the subchannels;
• a serial-to-parallel converting unit configured to split the transmission data into subchannel transmission data for as many subchannels as determined by said modulation control unit;
• a plurality of subchannel modulation processing units each configured to receive the corresponding subchannel transmission data for independent modulation processing so as to output a plurality of subcarrier transmission signals, each of said subchannel modulation processing units including
• 1) a frame generation unit configured to construct a frame by inserting a predetermined pilot sequence in the subchannel transmission data,
• 2) a data modulation unit configured to subject the subchannel transmission data of a frame structure to a predetermined data modulation process so as to output a modulated signal,
• 3) a data hopping unit including at least one multiplier and configured to output a plurality of subcarrier transmission signals corresponding to the respective subcarriers, by receiving the modulated signal, generate a predetermined hopping pattern of a predetermined sequence length, and output as the subcarrier transmission signal only the modulated signal carried in a subcarrier designated by the hopping pattern, while maintaining the other subcarrier transmission signals at a zero output level;
• an inverse Fourier transform unit configured to subject the entirety of subcarrier transmission signals output from said data hopping unit of said plurality of subchannel modulation processing units to inverse Fourier transform so as to output transmission signals multiplexed using said plurality of subchannels in which frequency-hopping spectrum-spreading is effected;
• and
• a guard interval (GI) inserting unit configured to insert a predetermined guard interval to the transmission signal output from said inverse Fourier transform unit.

A spread-spectrum modulation method in which transmission data is subject to spectrum spreading using a predetermined number of subcarriers, comprising the steps of:

• multiplying at least one pseudo random value to produce at least one weight factor;
• generating a hopping pattern of a predetermined sequence length, based on the at least one weight factor, and switched at a predetermined hopping frequency, the hopping pattern designating a subcarrier for frequency hopping;
• outputting a plurality of subcarrier transmission signals corresponding to the plurality of subcarriers, respectively, by receiving the transmission data and outputting as a subcarrier transmission signal only the transmission data carried in a subcarrier designated by the hopping pattern, while maintaining the other subcarrier transmission signals at a zero output level;
• and
• subjecting the entirety of subcarrier transmission signals to inverse Fourier transform so as to output frequency-hopped spread-spectrum transmission signals.