Title :
Time-frequency spread OFDM/FHMA
Author :
Hamaguchi, Kiyoshi ; Hanzo, Lajos
Author_Institution :
Commun. Res. Lab., Yokosuka, Japan
Abstract :
A combined scheme based on orthogonal frequency-division multiplexing and frequency-hopped multiple access (OFDM/FHMA) is proposed, in which the transmitted data is spread over both the time and frequency axes without expanding the bandwidth. The OFDM system advocated employs the Walsh-Hadamard transform (WHT) for spreading the data in the frequency domain and weights the received signal by the estimated signal-to-interference ratio (SIR) for the sake of reducing the effects of interference. The performance recorded, when communicating over an interference-limited channel suggests that the achievable BER improvement is as much an order of magnitude to that of an OFDM/FHMA scheme dispensing with WHT.
Keywords :
Hadamard transforms; OFDM modulation; error statistics; frequency hop communication; interference suppression; multi-access systems; spread spectrum communication; telecommunication channels; OFDM; Walsh-Hadamard transform; frequency-hopped multiple access; interference suppression; orthogonal frequency-division multiplexing; signal-to-interference ratio; time-frequency spread; Bandwidth; Bit error rate; Frequency domain analysis; Frequency estimation; Multiple access interference; OFDM; Quadrature amplitude modulation; Radiofrequency interference; Spread spectrum communication; Time frequency analysis;
Conference_Titel :
Vehicular Technology Conference, 2003. VTC 2003-Spring. The 57th IEEE Semiannual
Print_ISBN :
0-7803-7757-5
DOI :
10.1109/VETECS.2003.1207827
