Transmitter for extending guard interval for individual user equipment in ofdma systems

A transmitting apparatus for extending a guard interval of data transmitted to terminals which are predicted to have delay extension or a timing error greater than a guard interval in an OFDMA system, comprising:

• a guard interval extension processing means for generating symbols with a guard interval extended by copying a part of a current symbol and pasting the coped part to a last part of a previous symbol;
• an up-sampling processing means for receiving the processed symbols from the guard interval extension processing means and performing an up-sampling process;
• an interpolation processing means for performing circular convolution based on an interpolation filter value to load frequency-domain data on corresponding sub-carriers for the outputs of the up-sampling processing means;
• and
• a cyclic prefix insertion means for inserting a cyclic prefix code to output of the IFFT processing means.

A transmitting method for extending a guard interval of data transmitted to terminals which are predicted to have delay extension or a timing error greater than a guard interval in an OFDMA system, comprising the steps of:

• a) generating symbols with a guard interval extended by copying a part of a current symbol and pasting the coped part to a previous symbol;
• b) spreading the symbols with the extended guard interval through Fourier transform;
• c) performing an IFFT process to allocate sub-carriers for the FT processed frequency-domain data based on a localized allocation method;
• and
• d) inserting a cyclic prefix code to the IFFT processed data.

A transmitting method for extending a guard interval of data transmitted to terminals which are predicted to have delay extension or a timing error greater than a guard interval in an OFDMA system, comprising the steps of:

• a) generating symbols with a guard interval extended by copying a part of a current symbol and pasting the coped part to a previous symbol;
• b) performing an up-sampling process on the symbols with the extended guard interval;
• c) interpolating the up-sampled symbols by performing circular convolution based on an interpolation filter value to allocate sub-carriers to the up-sampled frequency-domain data;
• and
• d) inserting a cyclic prefix code to the interpolated data.