Next Generation Space Link Protocol – Raison d’etre Greg Kazz Ed Greenberg SLS-SLP WG Fall 2013 CCSDS Meeting - San Antonio, TX, USA

Fall 2013 CCSDS Meeting - San Antonio, TX, USA Next Generation Space Link Protocol (NGSLP) Enablers What the current SLPs do not provide Meets the need of optical comm for higher data rates (10 Gbits) by using larger frames (65Kbyte) and longer sequence counts (up to 7 bytes) Current max frame size is 2048 bytes – in comparison to other data links using optical comm their transfer frames sizes are much larger to minimize header overhead given these large data rates. Last page address frame sequence counter roll over issue. There are ways to kluge a smaller frame count with ERT as G.P. suggested, but that makes accountability more complex and is it really necessary? Enables larger SCID name space (722/1024 V1 and 161/256 V2). We don’t really know the true state of the current SCID name space as Marc B. knows. We know there will be greater demands on that space due to smaller spacecraft such as cubesats, microsats, etc We need to plan ahead to increase this name space. NGSLP proposal is to at least double it to 2048 IDs. Decouples channel coding from data link layer protocol. Facilitates better modularity. The emerging trend is to do this. True for both SCCC and DVBS-2. The CCSDS transfer frame size would no longer be tied to the underlying codeblock length. Also we can switch out the data link layer and not affect the physical layer or coding sublayer. We recently accomplished this on Electra implementation of LDPC on MAVEN and future NASA mars missions. Single link layer protocol for all mission types. Vendors and agencies need only implement and test and manage one protocol for all links (manned, robotic, near earth , deep space, Lagrange). New VC subchannel field to allow one COP and one SA for multiple users. Amongst other things meets NASA/JSC need to multiplex multiple users (identified by VC subchannel) required to use the same VC under one SA controlled through Houston POCC. Brings SDLS to Prox Comms using VCs. Currently Prox-1 cannot use SDLS because there are no VCID concept. Mars Program was always concerned that this reason excluded Prox-1. The other reason SDLS WG excluded Prox-1 is because they felt security wasn’t an issue at Mars. However, prox-1 is not exclusive to Mars. It could be used in any proximity environment. Therefore it seems short sighted by CCSDS if SDLS does not apply to Prox-1. Provides all the data required to do Master Channel Services (no managed parameters). Trend is to make processing more data driven where it makes sense. Currently we believe it makes sense to do so here. Supports Frame Relay for LEO to GEO to Earth links. The same transfer frame can be relayed across multiple spacecraft, since the same structure is used across all links. Fall 2013 CCSDS Meeting - San Antonio, TX, USA

Fall 2013 CCSDS Meeting - San Antonio, TX, USA Backup At 10 Gbit/sec with the current AOS frame size (16,384 bits), the Extended frame sequence counter (28 bits) rolls over in ~ 7 minutes. If the sequence count was extended to 56 bits, the sequence count roll over would occur in ~ 3700 years. Fall 2013 CCSDS Meeting - San Antonio, TX, USA