A new blind channel shortening for differential encoded OFDM system

Abstract

In OFDM systems, the inter-symbol interference and inter-block interference are eliminated by using null-tones (NT) and cyclic prefix (CP) redundancy of length higher than the channel size. To preserve a high bit rate, channel shortening method is required to reduce the redundancy. Recently, channel shortening technique with differential encoded OFDM systems without the NT was introduced. This technique is very simple and achieves the channel shortening using only one symbol (the first emitted symbol). In this paper, we prove that, in the presence of null-tones (used in most OFDM-based communication standards), the performance of the previous technique decreases. Therefore, we propose an alternative solution that improves the receiverpsilas performance and preserves a high BER (Bit Error Rate) quality in presence of null-tones.