Capacity Analysis and Improvement of LDM-Based Multiple-PLP Configurations in ATSC 3.0

This article analyzes the capacities of various layered-division multiplexing (LDM)-based multiple physical layer pipe (M-PLP) configurations in Advanced Television Systems Committee (ATSC) 3.0. Further, this article proposes an extended multi-layer LDM that consists of a core layer and one or more enhanced layer(s) combined with different injection levels. The proposed multi-layer LDM can be combined with time-division multiplexing (TDM) and/or frequency division multiplexing (FDM) to multiplex more than two PLPs. This article provides the structures of a transmitter and receiver for the multi-layer LDM and various M-PLP configurations based on the proposed multi-layer LDM. In addition, by extending to a multi-layer LDM, the low rate low-density parity-check (LDPC) codes are proposed to improve the transmission efficiency of an extremely robust service with lower data rate, such as robust audio, in the core layer of the multi-layer LDM. Simulation results show that the M-PLP configurations based on more than two layers can obtain the improved reception performance compared to the M-PLP configurations based on only two layers supported by the PHY standard in ATSC 3.0. However, since the performance degradation of layered time-division multiplexing (LTDM) with fewer layers is not significant compared to multi-layer LDM, LTDM can be a good solution to efficiently transmit M-PLPs.

I. Introduction

Advanced Television Systems Committee (ATSC) 3.0, which is the latest terrestrial broadcasting standard, has been developed to support broadcasters’ and users’ requirements for higher quality broadcast services. Various technologies, which achieve higher capacity, spectrum efficiency, and robustness than ATSC 1.0 and previous digital television standards, are applied to the physical layer (PHY) standard of ATSC 3.0 [1], [2]. In the PHY of ATSC 3.0, up to 64 physical layer pipes (PLPs) can be simultaneously transmitted. The basic structure of the PHY of ATSC 3.0 consists of four parts, i.e., input formatting, bit-interleaved coded modulation (BICM), framing and interleaving, and waveform generation. First, the input formatting block transforms the ATSC link-layer protocol packets from a higher layer to baseband frames [3]. In the BICM block, by performing channel coding and symbol mapping for the input baseband frame, a coded and mapped signal is generated [4]. For the channel coding, the outer and inner codes are performed in that order. As an outer code, the Bose, Ray-Chaudhuri, and Hocquenghem (BCH) code or cyclic redundancy check (CRC) may be used or the outer code may not be used. As an inner code, a low-density parity-check (LDPC) code is adopted with code rates from 2/15 to 13/15 for a code length of 16200 and 64800, respectively [5]. The symbol mapping supports quadrature phase shift keying (QPSK) and quadrature amplitude modulation (QAM) with 16/64/256/1k/4k non-uniform constellations (NUCs) [6]. Using a different NUC shape according to the LDPC code rate, an improved reception performance can be obtained when compared with the conventional uniform constellations [7], [8]. Then, in the interleaving and framing block, time interleaving, framing, and frequency interleaving are performed, respectively. Further, a final transmit signal is generated in the waveform generation block. Furthermore, multiple-input multiple-output (MIMO), multiple-input single-output (MISO), and channel bonding (CB), which use multiple antennas or additional radio frequency (RF) channels, are adopted as optional technologies in ATSC 3.0. Using MIMO, MISO, and CB, higher data rate and/or robustness can be achieved when compared with a single-input single-output (SISO) system [9]–[11].