[e2e] Wireless Networks. An Example: GPRS.

[Martin Heusse]

(Although I would tend to think you might need to read a bit about GPRS and cellular networks, I'll stick to a more general remark, replacing your reflections in an end to end perspective. And forgive me if I misunderstood you.)

A sliding window (congestion window, anticipation window) allows a sender to use the links on a multi hop paths in parallel when the network device are store and forward. So to use a GPRS network properly you need a least 4 packets.
UE -> BSC 
-> SGSN
-> GGSN
-> gateway to dest network
Etc.

And that's one way, the return path also count for what's “inflight".
(ok, high speed links don't hurt as much a low speed links beyond the bottleneck, but I hope you get the idea…)

Also: RLC-ack (Is that what you call RLP?) does use ARQ… (Are you happy now? ...) And that actually allows TCP to kind of work on those links.

Martin


Le 11 mars 2013 à 13:19, Detlef Bosau a écrit :

> And because the real air interface has hardly any "transient storage capacity" at all, I think, a sliding window approach for GPRS networks is completely inappropriate. We should use stop 'n wait here and that's it.