Radioengineering (Jun 2021)
Implementation of a 3-layer LDM Broadcast System Backward-compatible with ISDB-TB
Abstract
This paper presents an implementation of a 3-layer transmitter and receiver using Layer Division Multiplexing (LDM), in Software Defined Radio (SDR). The main idea of this work is to show another point of view of the traditional LDM technique that uses two layers. This proposal uses an attenuated intermediate layer, called Middle Layer (ML), between the highest power layer, called Upper Layer (UL), and the most attenuated layer, called Lower Layer (LL). The UL is fully compatible with the Integrated Services Digital Broadcasting Terrestrial - Version B (ISDB-TB). The ML, with greater robustness, and LL, with higher capacity, use powerful channel coders, a custom frame size and an adapted bit interleaver. With the use of this modified LDM, it is possible to develop a system with different robustness levels between layers and with lower layers that complement each other, to achieve bit rates that allow for the deployment of High Definition Television (HDTV), in the UL, and Ultra High Definition Television (UHDTV), in the ML and LL. In addition, a system was also implemented with three layers, but with the ML with higher capacity and the LL with greater robustness. The performance of the 3-layer system was compared with the 2-layer LDM technique and there was an improvement in the system modularity, without a decrease in the bit rate.
