RF&Mod services from CIS-Lunar WG Single access? Multiple access? –To/from several s/c simultaneously from one station? (many to one) This might be useful for voice from Earth to a pair of remote elements (like two capsules or a lunar base and a DTE-capable rover). –To/From different stations to several s/c simultaneously? ( many to many) –Probably a mix of things here. The space may break into essentially three classes of comms: Short-range that might be supportable via like mechanisms (crew module to suit, lunar astronaut to rover, …) Multiple access would probably be good here Mid-range comms that look sort of like prox-1: surface-to-orbit kinds of distances. A multiple access scheme might be nice here but would probably be problematic due to the delays. Long-range comms that might be supportable by something like AOS: DTE/DFE kinds of links to in cruise things, e.g. We will need the ability to relay communications. That is, we’ll probably want to support a concurrent data path like astronaut suit (short-range) to rover (prox range) to relay satellite (long range) to Earth. Broadcast mode? –Would like to have some sort of multiple access or broadcast mode so that two things that don’t necessarily know about each other can find each other. Should the uplink channel be optimized for link margin ? –See uplink bandwidth below. –Might have separate channel with high link margin for very high reliability / emergency commanding. What bandwidth is required? –Uplink: Probably need to support a couple of concurrent voice-over-network (VOIP-type) calls plus a lower rate video uplink plus some bandwidth for command and control. –Downlink: Maximum to support at least uncompressed HDTV plus ‘regular’ telemetry plus a few voice channels. Frequency bands ? –Don’t think we particularly care. What are the physical channel characteristics? –Fading? Multi-path? –Maybe some multipath on surface-to-orbit links (seen any on MER?) Data rates required (What’s the bottleneck) ? Doppler and Doppler rate ? –For the short-range comms, essentially none. –For the mid-range comms, doppler and doppler rate to support lunar surface to ~50km lunar orbit. Security requirements at the physical layer ? – I Wish I knew… Link layer encryption is transparent to us, probably NOT LPI/LPD requirement Is the RF link bursty or continuous? – Suspect continuous.

Coding services from CIS-Lunar WG What is the acceptable FER for a given SNR? –I’d couch the requirement a bit differently. Need to keep the error rate such that we see <~2- 5% loss on ~1500-byte frames. How much coding overhead can you tolerate given the gain ? –Don’t think we particularly care about this metric individually. We need the data/error rates. Is spectral efficiency an issue ? –For near-Earth and lunar operations, spectrum is limited, so efficiency will probably be an issue given the rather aggressive data rates we’re looking for. How well can you tolerate latency in data delivery ? –Depends on where we are. For near-Earth and Lunar missions, people would like to do 2- way voice over the network. Maybe something like “latency expansion < max(xx % of one- way light time, yy ms)”? What’s the probability of undetected error on the frame? –We would like to keep this pretty low, preferably to crc-32 kinds of levels. ************************************************* Do you need a bi-directional approach for uplink/downlink? –Not required but desired (esp. for 2-way voice and TCP traffic). These don’t have to be on the same physical channel, but would need to run concurrently.

Link Layer services from CIS-Lunar WG Are reliable communications required ? –What does ‘reliable’ mean? Reliable data link is probably not required for the low-latency cases (out to surface-to-orbit). Might be useful for long-haul links. Are the messages fixed or variable length? –Variable Do you have a synchronous and/or asynchronous data link? –Mixed Is there a need to multiplex data types i.e., IP, CCSDS Space pkts, other on the same link? –Yes, including IP over CCSDS What indicators do the upper layers need from the link, coding, and RF layers? –Link still alive indication? –FER, SNR estimates? What are the data delivery QoS required? –In order delivery? - Not required. –Tolerate duplicates or not? - Can tolerate duplicates. –“Error free” delivery - Very low probability of undetected errors. –Latency requirements – As above –Data Continuity requirements – “Continuity?”