Subject: RE: : [manet] manet

From: "Green, David B RDECOM CERDEC STCD SRI" <[email-masked]>
Date: Thu, 18 Mar 2004 15:10:18 -0500

Kani,
    Your wireless system should decide at the PHY and MAC layer what
constitutes a good packet. There is a minimum receive threshold in the
physical layer - you can't receive a signal below that signal to noise
ratio. Also, the MAC layer generally institutes a checksum on frames to
ensure they are not damaged. Generally anything that gets up above that gets
handed to upper layers. You may be able to tap into some neighbor
information from layer 1-2 (you can in many WLANs) to see the relative
signal strength from a neighbor and determine if that neighbor is marginal
or is fading out so you can pro-actively avoid link failure. Some
experimental MANET protocols implement such a system when assigning link
weights to relays. The "forward handoff" in cellular systems uses the same
principle.

David B. Green
SRI International

RE: [manet] manet

*	To: "'kani mozhi'" <kani_11 at rediffmail.com
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*	Subject: RE: [manet] manet 
*	From: "John Mullen" <jomullen at nmsu.edu
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*	Date: Thu, 18 Mar 2004 12:17:18 -0700 
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Title: Message
Hi, 
The answer to your question depends primarily on 1) average received
signal-to-noise ratio, 2) waveform and encoding, 3) shadowing, 4) fading,
and 5) packet size. Average received radio S/N itself depends mainly on
frequency, the composition of the environment, terrain, antenna gain and
distance. Other factors include decisions made at the MAC and link levels on
what constitutes a reliable link. Given the RF complexity of a typical MANET
manifestation, these parameters will differ from place to place. As a
result, you will need some sort of adaptive rule. 
John Mullen 
-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of kani
mozhi
Sent: Thursday, March 18, 2004 11:42 AM
To: [email-masked]
Subject: [manet] manet

hi
iam working on intrusion detection and response for adhoc networks.

what is the probability that a node will experience link error when
receiving and forwarding packets
i need this to set a threshold value such that it mitigates the link error 

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