European Space Agency

PreDem - Precoding Demonstrator for Broadband System Forward Links


The objective is to develop a comprehensive software simulation platform (the demonstrator) that will prove the concept of precoding in the forward link of DVB-S2X based broadband interactive satellite system. The demonstrator will provide a powerful tool in support of the design of next generation broadband systems that aggressively re-use the available system bandwidth. DVB recently issued the DVB-S2 extension (DVB-S2X) with an optional specification that provides the necessary framing and signaling support to interference management techniques (like precoding). Thereby, all elements to support precoding in terms of physical layer have been put in place and the technique is awaiting a proof-of-concept.


The goal of Terabit/s throughput using multiple spot beam high throughput satellite (HTS) systems requires the development of new techniques, technologies. Current solutions use the conventional four colour scheme. Due to the fact, that frequency is a scarce resource, the available spectrum needs to be reused as much as possible to increase throughput. This leads to a high level of intra-system interference between the co-channel beams. Joint processing of the signals intended to the different beams can be carried out at the transmitter (usually the gateway or hub) for interference management. This processing, is referred to under the generic term precoding, which ‘reverts’ the impact of the satellite RF channel and interferences.


The PreDem simulator is a valuable tool that allows assessing the performance of precoded and non-precoded multibeam satellite systems. 

The PHY simulator focuses on generating and collecting statistics for deriving the CSI error model and the estimated precoded SNIR model, which are used in the SYS simulator in order to abstract the behaviour of the receivers, while the system level simulator focuses on the generation of long term statistics of the precoded system including scheduling and application layer measurements. 

Together, they form a highly configurable toolset, which makes it possible to investigate the effect of many system parameters on the precoding performance as well as the QoE experienced by the user terminals.

System Architecture

The PreDem demonstrator is a tool that is able to carry out precoding simulations on both the physical layer (PL) level and the system level. While PL level simulations are performed on the samples of the transmitted signals of just a few receivers during a short period of time, system level simulations work on a higher level with many receivers and beams, preferably over duration of several months.

Due to the different nature of these simulation levels, the simulation workflow of the PreDem demonstrator is split into two stages, namely a PHY simulator simulating the physical layer, and a SYS simulator for the system level. As far as possible, common modules of both simulators are re-used. Using this approach, each of the two simulators can concentrate on its core functionality, and simulations can be carried out independently.

Current status

The project is completed.

Status date

Tuesday, September 18, 2018 - 10:31