5 ms·

> While I don't doubt your line of reasoning, one would assume these factors were taken in to account by the specialists who designed the protocols and they wou

by roeles 5y ago

> While I don't doubt your line of reasoning, one would assume these factors were taken in to account by the specialists who designed the protocols and they would have used obvious strategies like reducing the time domain for new peer associations and added predictive schedules for ongoing transfers. These must be common building blocks in radio protocol engineering. In wifi, this is handled by the base station if I'm correct. It assigns slots for the associated receivers. Assigning slots in a mesh network without coordination is effectively a graph coloring problem and difficult to solve. My professor for my master thesis was the author of LMAC, which attempted to assign slots to each node. It worked great in theory, but not so much in practice.

contingencies 5y ago
LMAC (2003) @ https://research.utwente.nl/files/5427399/VanHoesel_INSS04_048.pdf https://research.utwente.nl/files/5427399/VanHoesel_INSS04_0... seemed to target energy efficiency on bursty, short messages on fixed topology wireless networks, whereas we were discussing the potential for ad-hoc mesh for a general use case using existing wireless chipsets. To take up the tangent, it seems to me that the graph coloring problem can either be (1) solved universally (any local mesh will have distinct boundaries which make absolute coordination feasible) by adding some sort of explicitly negotiated or progressively developed shared state to act as a coordination layer (2) solved temporarily, for example by implementing a best-effort failover/fallback (CSMA/CD feeds back to "color") (3) Ignored. Solution class 1 is obviously challenging to apply to for mobile and ad-hoc mesh networks. Solution class 2 seems more realistic for this category of use case. Solution class 3 works well if you have full control of the application layer (eg. wireless sensor network is push-only with short packets with high temporal tolerance for retransmissions). Feels a bit like "Energy optimization / throughput / ad-hoc topology / traffic generality. Choose any three."

by roeles 5y ago

contingencies 5y ago

LMAC (2003) @ https://research.utwente.nl/files/5427399/VanHoesel_INSS04_048.pdf https://research.utwente.nl/files/5427399/VanHoesel_INSS04_0... seemed to target energy efficiency on bursty, short messages on fixed topology wireless networks, whereas we were discussing the potential for ad-hoc mesh for a general use case using existing wireless chipsets. To take up the tangent, it seems to me that the graph coloring problem can either be (1) solved universally (any local mesh will have distinct boundaries which make absolute coordination feasible) by adding some sort of explicitly negotiated or progressively developed shared state to act as a coordination layer (2) solved temporarily, for example by implementing a best-effort failover/fallback (CSMA/CD feeds back to "color") (3) Ignored. Solution class 1 is obviously challenging to apply to for mobile and ad-hoc mesh networks. Solution class 2 seems more realistic for this category of use case. Solution class 3 works well if you have full control of the application layer (eg. wireless sensor network is push-only with short packets with high temporal tolerance for retransmissions). Feels a bit like "Energy optimization / throughput / ad-hoc topology / traffic generality. Choose any three."