A Hierarchical OFDM System for Mobile Reception and Single Frequency Networks

Abstract

It is desirable that digital terrestrial broadcasting systems provide services not only to fixed receivers through single frequency networks (SFN) but also services to mobile receivers. This paper studies suitable values for the OFDM parameters of SFNs and mobile receivers respectively, and it proposes a new OFDM technique called MSL-TDM (Multi-Symbol-Length Time Division Multiplexing) which multiplexes symbols of different lengths for mobile and fixed reception. By using MSL-TDM, we can construct both large scale SFNs and mobile receivers simultaneously on a single transmission channel. This paper presents the concept of MSL-TDM and it provides an outline of an experimental modem. It also describes some results obtained from indoor experiments. These indicate that the system works well in both Gaussian and Rayleigh channels. There was no difference in results measured by one hierarchical transmission and two hierarchical transmission.