[londons_explore]

Most wireless networks seem to have loss in the range 0.1% - 1% due to congestion (ie. when a packet is clobbered by noise of some far off transmitter that the media access control algorithms could not protect against).

In that case, Layer 2 retransmission (ie. retransmission at an individual link rather than needing to retransmit a packet across the entire route) becomes absolutely necessary if there are many wireless links on a route.

What systems use layer 2 retransmission? My home wifi does not seem to...

[sathackr]

This is one of the biggest problems I have seen with attempted real-world deployments of wifi-based mesh systems.

Another issue is the half-duplex, CSMA nature of Wifi. It all but guarantees high amounts of jitter and latency instability. Particularly when several nodes in the same path are still in signal-range of one another so effectively share the same collision(and inteference) domain. A->B->C->D

I've found this wreaks havoc on TCP connections as well as applications that require some ability to detect and adjust to link condition.

This becomes significantly worse once the typical levels of WIFI interference come into play, causing multiple retransmissions and lost packets.

[tralarpa]

Frame retransmissions exist in CSMA for IEEE 802.15.4.

[noselasd]

Yes, your home wifi does. For unicast frames, an ack is required from the receiver, else the frame is re-transmitted.