DVB-RCS2 (Second Generation Return Channel Satellite) - Lower Layer

Introduction

The present document is a specification of the lower layers and the lower layer embedded signalling for the management and control system, for two way interactive satellite networks specified by ETSI TS 101 545-3 [i.16]. It represents a new generation of ETSI EN 301 790 [1]. The following amendments have been made relative to ETSI EN 301 790 [1]:

• The modulation schemes are CPM, 8PSK and 16QAM, in addition to QPSK.
• The FEC for QPSK, 8PSK and 16QAM is a 16-state turbo code, commonly called Turbo-phi.
• The FEC for CPM is Convolutional Coding.
• The waveform characteristics are configurable to allow adaptation to different applications.
• A set of normative reference waveforms are specified, to support interoperability.
• The MF-TDMA burst constructions for the reference waveforms are differentiated with respect to the
  operating point, by balanced use of preamble, postamble and pilots so that the decoder synchronization sensitivity threshold corresponds with the payload decoding sensitivity threshold.
• The forward link packet encapsulation uses GSE as specified in ETSI TS 102 606 [8] with strengthened
  integrity control to comply with the recommendations for internet subnet-working as found in IETF
  RFC 3819 [9]. Alternative encapsulation over a TS Packet stream is supported for migration.
• The return link packet encapsulation is an adaptation of the generic stream encapsulation (ETSI
  TS 102 606 [8]), where the IP packets are fragmented just in time so that the fragments fit exactly into the remaining free space of varying size available in the transmission frame payloads of different size, without using an intermediate fixed frame size streaming layer like ATM and MPEG TS. This new encapsulation protocol for the return link was named RLE (Return Link Encapsulation).
• The link transport specification is generalized to suit a multitude of protocols, not only IP. This applies to the forward link as well as the return link and to the design of the RLE protocol. The support of transport of other protocols than IP is however considered implementation dependent.
• Support for random access user traffic is included.
  The framing structure of the return link is simplified.
• The payload size can be adapted by selecting a suitably sized burst. Bursts are a low number of multiples of a unit timeslot, and bursts of different size can be fitted to the unit grid by concatenating unit timeslots to larger timeslots that can hold larger bursts. This concatenation may be done just in time.
• The modulation and coding to be used in a timeslot can be selected independently, allowing per timeslot ACM for more granular and more flexible link adaptation. The adaptation for a timeslot may be done just in time.
• Power headroom reporting is included. The power control system supports an optional control mode aiming for constant power spectrum density over carriers of different BW as an alternative to control the EIRP.

Version 1.4.1 of the present document provides support for signalling about non-geosynchronous satellites (non-GSO) and about forward links using Annex E (superframes) of DVB-S2X ETSI EN 302 307-2 [16], used by multibeam satellites, for interference suppression, pre-coding and beam-hopping. Additional signalling relevant for beam-hopping systems has also been added.

The present document allows substantial configuration flexibility in that the burst constructions and FEC can be adapted to some extent to the operating environment of the RCST. In order to guide in implementation and interoperability a set of reference burst configurations are specified, and the essential configuration space for such configuration is also indicated.

Clause 2 provides the references. Clause 3 provides the definitions of terms, explains symbols and expands abbreviations. Clause 4 provides further guiding in the reading of the present document through the introduction of reference models. Clause 5 specifies the forward link. Clause 6 specifies the syntax and coding of the lower layer signalling system components used in the forward link. Clause 7 specifies the return link. Clause 8 specifies the syntax and coding of the lower layer signalling system components used in the return link. Clause 9 specifies the management and control functions supported via the network internal L2S system. Clause 10 is reserved for future specification of the operation of mobile terminals. Clause 11 addresses security. Annex A provides the normative reference burst constructions. Annex B provides the CC-CPM interleaver permutations in tabular form. Annex C provides the CPM pulse shape specification in tabular form. Annex D provides the bibliography list.

Scope

The present document is a specification of the lower layers and the lower layer signalling system for the two-way satellite network variants defined by ETSI TS 101 545-3. The present document constitutes a complete specification of the lower layers for a transparent star satellite network, a transparent mesh overlay satellite network and a regenerative remultiplexing satellite network. Also, components required for a satellite network with a TRANSEC system are included.

The present document is normative for the consumer terminal profile in a transparent star satellite network as defined by ETSI TS 101 545-3, and does also include normative components specific to the other terminal profiles and satellite network variants defined by ETSI TS 101 545-3.