Subject: RE: [seamoby] RE: [seamoby-context] DOS in wireless

From: Phillip Neumiller <[email-masked]>
Date: Tue, 12 Jun 2001 15:54:47 -0400

Bzzzt.  Let's be specific here.  IS-95, cdma2000, umts all have
slightly different anti-jam characteristics. For IS-95

Jamming Margin = W/R (dB) - (Eb/No)req(dB)

So W/R is just the processing gain (varies in IS-95 with coding
rate), and Eb/No is the channel's signal to noise ratio.  

I can guarantee you that I can build a different CDMA system
that you can not Jam with your ham shack or radio shack parts.  

>Madjid: 
>  This is absolutely wrong. I guarantee you that it is possible to 
>jam a CDMA channel with CAN$50 of hardware from radio shack. Indeed, 
>as other posters have indicated, it has happened already by accident.

---

From: Arthur Ross <[email-masked]>
Date: Tue, 12 Jun 2001 13:24:02 -0700

>rate), and Eb/No is the channel's signal to noise ratio.

Close - "Jamming margin" isn't really the whole story - it's a question of
fraction of available Shannon capacity, which is mutual
interference-limited in the multiple access case for asymptotically high
powers from everybody. A jammer eats into that capacity to an extent that
depends on how the normal users do power control and their max Tx powers.

- ask me for that 2 hour version sometime .... :-)

   -- ahmr