An analysis of orthogonal frequency-division multiple access

We analyze the performance of orthogonal frequency-division multiple access (OFDMA) for the return channel on CATV networks, and compare this technique to the well-known time-division multiple access (TDMA). We examine the basic implementation issues of OFDMA including clock and carrier frequency synchronization, power control and ranging, and point out how these problems can be solved in practice. We also address some additional issues such as frequency hopping and strict bandlimiting of individual carriers. Our analysis indicates that OFDMA is an attractive multiple access technique which offers increased robustness to narrowband interference, impulse noise, and other signal impairments which characterize typical CATV networks.