SOURCEFORGE » RALF » 2014 ACM testing using channel emulation

h1. Satellite Channel Emulation

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This is the Wiki page for the SCS 2014/2015 project #1. It deals with DVB-S2 and its novel ACM feature.

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h2. Table Of Contents

* [[Main Page|Introduction]]

* [[DVB-S2]]

** [[Overview]]

** [[Adaptive Coding and Modulation]]

** [[FlexACM]]

* [[Lab Setup]]

** [[Link Emulator]]

** [[Newtec EL470]]

*** [[Configuration]]

** [[Measuring Tools and Scripts]]

* [[Results and Conclusions]]

h2. Progress

+@Tasks:@+

* %{background: none}@Introduction Section:@%

** %{background: lightgreen}@Why ACM is necessary.@%

** %{background: lightgreen}@Block diagram of ACM functionality.@%

* %{background: none}@DVB-S2 Section:@%

** %{background: yellow}@A little bit of history.@%

** %{background: yellow}@Features vs DVB-S.@%

** %{background: yellow}@Coding and modulation schemes.@%

** %{background: yellow}@ACM(Read EL470 Manual).@%

*** %{background: yellow}@Description.@%

*** %{background: yellow}@Newtec FlexACM@%

* %{background: none}@Test Setup Section:@%

** %{background: yellow}@Newtec EL470: Description of hardware.@%

*** %{background: yellow}@Configuration: Description of IP bridging@%

+@ColorReference:@+

* %{background: Lightgreen}@Task 1, Status: DONE@%

* %{background: yellow}@Task 2, Status: TODO@%

** %{background: Red}@SubTask 1, Status: URGENT@%

h2. Introduction

Satellite systems based on the DVB-S standard are inevitably forced to adhere to fixed MODCOD parameters, that is, a fixed coding rate and modulation scheme. This in turn leaves the designer with no choice other than to dimension the system for the worst-case propagation conditions in order to have link-closure and meet availability, coverage and performance requirements. 

This approach has the disadvantage that high margins in the carrier-to-noise-and-interference ratios (CNIRs) occur in the majority of cases when propagation conditions allow for it. In the case of broadcasting services, where we have a multitude of users spread over very large areas, this waste of power cannot be easily avoided. However, in point-to-point links if a return channel is present it is possible to report channel state conditions and exploit its temporal variations by adapting the code rate and modulation scheme being used so as to best match the CNIR. This way a fixed link is avoided and considerable improvements in system capacity are obtained with better utilization of power resources.

The DVB-S2 standard introduces adaptive coding and modulation (ACM) enabling better use of transponder resources when high carrier-to-noise-plus-interference ratios occur due to favorable propagation conditions. ACM allows for different coding rates and modulation schemes to be used and dynamically changed on a frame-by-frame basis.

!{width: 70%}acmLink.png(Block diagram of an ACM DVB-S2 link.)!

h2. Bibliography

In the course of this project we have used the ETSI's specifications of DVB-S as well as hardware manuals and several papers. These documents can all be found in the Documents section of this project. A list is provided here for convenience:

_User Manuals:_

project-channel-emulation:document#12

_Papers:_

project-channel-emulation:document#13

project-channel-emulation:document#3

project-channel-emulation:document#14

_ETSI Specifications:_

project-channel-emulation:document#1

project-channel-emulation:document#2

project-channel-emulation:document#4