Multicast streaming on wireless

gnijs · ‎01-30-2009

Hi all,

I want to start streaming multicast video across wireless. Lucky for me, the stream isn't of too high bandwidth (100-200 kbps). However, it is multicast based so: UDP packet streaming, no ACK mechanisme.

Our setup is completely WISM based.

However, i have done some tests in the lab streaming 50 pkts/seconds to my wireless PC (connected in 54mbps g, excellent signal quality) and i get about 13% packet drops. Much too high drop rate for video streaming.

What methods are available to decrease this drop rate on wireless ?

Any docs will help,

regards,

Geert

gnijs · ‎01-30-2009

After doing some more research about EDCF and WMM (QOS things to improve voice over wireless), i am trying to set this up for the multicast streaming.

However, in the Unified Wireless Multicast Design guide, i see "The QOS bits of the LWAPP multicast packet are hard coded at the lowest level and are not user changeable". And indeed, i have done a sniffer capture of a multicast stream: it enters the controller with DSCP EF, however the LWAPP encapsulated packets to the LWAPP distribution group have DSCP 0.

According to the QOS Voice design guide, the DSCP marking of the original packet is transferred into LWAPP packet and from their on the 802.11.

Does this mean that the whole EDCF and WMM stuff to improve QOS on wireless, doesn't effect the multicast stream ? So with real multicast, i am stuck with QOS = 0 ??