Layered Division Multiplexing Research Articles

Performance Study of Layered Division Multiplexing Based on SDR Platform

Two of the main drawbacks of the current broadcasting services are, on the one hand, the lack of flexibility to adapt to the new generation systems requirements, and on the other hand, the incapability of taking a piece of the current mobile services market. In this paper, layered division multiplexing (LDM), which grew out of the concept of Cloud Txn, is presented as a very promising technique for answering those challenges and enhancing the capacity of broadcasting systems. The major contribution of this paper is to present the first comprehensive study of the LDM performance behavior. In particular, in this paper, the theoretical considerations of the LDM implementation are completed with the first computer based simulations and laboratory tests, covering a wide range of stationary channels and the mobile TU-6 channel. The results will support LDM as a strong candidate for multiplexing different services in the next generation broadcasting systems, increasing both flexibility and performance.

Cloud Transmission: System Performance and Application Scenarios

Cloud transmission (Cloud Txn) is a flexible multilayer system that uses spectrum overlay technology to simultaneously deliver multiple program streams with different characteristics and robustness for different services (mobile TV, HDTV, and UHDTV) in one radio frequency channel. Cloud Txn is a multilayer transmission system like layered-division multiplexing. The transmitted signal is formed by superimposing a number of independent signals at desired power levels to form a multilayered signal. The signals of different layers can have different coding, bit rate, and robustness. The upper layer system parameters are chosen to provide very robust transmission that can be used for high-speed mobile broadcasting. The bit rate is traded for powerful coding and robustness so that the signal-to-noise ratio (SNR) threshold at the receiver is in the range of ${-}{2}$ to ${-}{\rm 3}~{\rm dB}$ . The top layer is designed to withstand combined noise, co-channel interference and multipath distortion power levels higher than the desired signal power. The lower-layer signal can be a DVB-T2 signal or another new system to deliver HDTV/UHDTV to fixed receivers. The system concept is open to technological advances that might come in the future: BICM/non uniform-QAM, rotated constellations, time frequency slicing or MIMO techniques can be implemented in the Cloud Txn lower (high data rate) layer. The system can have backward compatible future extensions, adding more lower layers for additional services without impact legacy services. This paper describes the performance of Cloud Txn broadcasting system.

On the Performance of the Layered-Division-Multiplexing using Maximal-Ratio Combining

This article proposes the diversity gain enhancement in layered division multiplexing (LDM) systems by applying maximal-ratio combining (MRC) technique. LDM systems is adopted as a baseline technology of the ATSC 3.0 systems which the two transmission layers are simultaneously transmitted over two different types of fading channels for fixed and mobile services. Hence, the performance analysis of each layer need to be evaluated on different type of fading channel. Starting with the moment generating function (MGF) of the MRC output signal-to-noise ratio (SNR), we propose the new method to derive closed-form expressions for average symbol-error rate (SER) of the proposed systems over Rayleigh and Nakagami-m fading channels in the presence of error propagation (EP) that is generated from the first layer detection. Analytical results show that the specific value of injection level at the transmitter need to be precisely defined to obtain the best mutual benefit for both LDM layers, and the proposed technique has significant performance advantage over conventional LDM systems. Simulation results demonstrate the tightness of the author’s analysis.