IP characteristics for 3G and WiFi links

Mikael Abrahamsson swmike at swm.pp.se
Thu Aug 26 14:37:27 CDT 2010


On Thu, 26 Aug 2010, Daniel Migault wrote:

> Parameter           | Wifi (802.11a/g) | 3G (HSDPA)
> Latency                100 ms               60 ms
> Bandwidth             5 Mbps               3 Mbps
> Packet Lost Rate   XXX                   XXX

So, if you want to emulate HSPA you need to understand how it works. If 
you go from "idle" (30 seconds of not sending data) you will see 1-2 
seconds of jitter as radio resources are allocated and brought "online", 
until you can send packets. There are multiple states, either you have HS 
resources, or you have regular 384k channel, or you basically have "none". 
All of these have different characteristics.

Packet loss on 3G is really low as it does re-sends itself, normally you'd 
see muc less than 1% of packet loss, usually a lot lower than that. There 
is quite a lot of resending and assuring packets are not lost on multiple 
layers beneath IP in those networks.

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se




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