出版社：The Institute of Image Information and Television Engineers
摘要：A new approach to achieve SFN that uses OFDM is described. In the SFN emvironment, especially in a relay one, delay spread is sometimes longer than the guardintervals. This results in not only inter-symbol interference (ISI), but also inter-carrier interference (ICI), since orthogonality is lost. To avoid this, the relay station must remove the delay, since the symbol timing is simultaneous among stations. However, this is impossible, because the relay station reuses the received signal. We have thus changed the strategy to transmit the signal on different symbol timing. This is simplly achieved by inserting an additive delay at the relay station, and it makes possible to decrease an additive delay. Therefore, we can spread the region where ICI is avoided. Also described is a method to eliminate ISI by using the Viterbi algorithm. Experimental results showed that the service area becomes larger, because torelable delay becomes longer than in the conventional system. Moreover, the BER characteristics are imprived even in the service area of a conventional system, because strong frequency-selective fading does not occur when using the proposed system.
