Communication system for transforming signals between time domain and frequency domain using a defined discrete fourier transform size

A communication system comprising:

• a communication apparatus including
• a Discrete Fourier Transform (DFT) transformer which transforms a time-domain signal into a frequency-domain signal with a DFT size that is a product of powers of a plurality of values, the plurality of values being integer numbers that are greater than 1 and are different from each other, exponents for the plurality of values being a set of non-negative integers;
• a mapper which maps the frequency-domain signal on a plurality of frequency bands, each frequency band being located at a position separate from position(s) of other(s) of the plurality of frequency bands, wherein a size of each of the plurality of frequency bands is a product of two or more powers of prime numbers or a multiple of the product of the two or more powers of prime numbers, each of the prime numbers being an integer number that is greater than 1 and the prime numbers being different from each other, exponents for the prime numbers being a set of non-negative integers;
• and
• a signal generator which generates a single carrier-frequency division multiple access (SC-FDMA) time-domain signal from the mapped signal;
• and
• a base station including
• a receiver which receives the SC-FDMA time-domain signal;
• a combiner which generates the frequency-domain signal from the SC-FDMA time-domain signal;
• and
• a transformer which transforms the frequency-domain signal into the time-domain signal with an inverse Discrete Fourier Transform (IDFT) having the DFT size.