Frequency division multiplexing system with selectable rate

An orthogonal frequency division multiplex transmitter selectively operable in a plurality of modes, each of the plurality of modes employing the same set of sub-carriers, the transmitter comprising:

• a coding circuit that receives a stream of data bits and partitions the data stream into groups of bits, each group of bits forming a symbol;
• an inverse Fourier transform circuit, operably coupled to the coding circuit, that performs an inverse Fourier transform;
• and
• a prefix and window circuit, operably coupled to the inverse Fourier transform circuit, capable of switching between a first mode having a guard time TG and a symbol duration T, and a second mode having a guard time KTG and a symbol duration KT, where K is a positive integer greater than 1.

A method for transmitting an orthogonal frequency division multiplex (OFDM) communication signal, the method being selectively operable in a plurality of modes, each of the plurality of modes employing the same set of sub-carriers, the method comprising the steps of:

• coding a received a stream of data bits to partition the data stream into groups of bits, each group of bits forming a symbol;
• performing an inverse Fourier transform on ones of said symbols;
• and
• selectively operating a windowing function to switch between a first mode having a guard time TG and a symbol duration T, and a second mode having a guard time KTG and a symbol duration KT, where K is a positive integer greater than 1.