I-D ACTION:draft-degermark-crtp-cellular-01.txt,.ps

[[e-mail]]

A New Internet-Draft is available from the on-line Internet-Drafts directories.


	Title		: CRTP over cellular radio links
	Author(s)	: M. Degermark, H. Hannu, L. Jonsson, K. Svanbro
	Filename	: draft-degermark-crtp-cellular-01.txt,.ps
	Pages		: 22
	Date		: 14-Dec-99
	
This document evaluates the performance of a header compression
protocol for RTP, CRTP [RFC-2509], over links built on cellular radio
access technology. The key characteristics affecting CRTP performance
over such links are the high error rates and the relatively long
roundtrip time over the link.
Bandwidth is typically expensive in cellular radio access networks,
saving a single octet per voice packet can be equivalent to saving
many billion dollars in deployment since fewer base-stations are
needed. This is beneficial for operators as well as end-users who can
get cheaper wireless IP telephony service.
CRTP performance is evaluated for two kinds of link layers operating
over a realistic radio channel with high bit-error rates. Two main
conclusions are drawn. The first is that CRTP does not perform well
for this type of link. The second is that in high-error environments
it is very beneficial to have a checksum covering the compressed
header only, not the payload, so that the decompressor sees all non-
damaged headers. When a strong checksum covers the entire link layer
frame, header compression performs badly since too many headers are
discarded due to damaged payloads.

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-degermark-crtp-cellular-01.txt

Internet-Drafts are also available by anonymous FTP. Login with the username
"anonymous" and a password of your e-mail address. After logging in,
type "cd internet-drafts" and then
	"get draft-degermark-crtp-cellular-01.txt".

A list of Internet-Drafts directories can be found in
http://www.ietf.org/shadow.html 
or ftp://ftp.ietf.org/ietf/1shadow-sites.txt


Internet-Drafts can also be obtained by e-mail.

Send a message to:
	[e-mail].
In the body type:
	"FILE /internet-drafts/draft-degermark-crtp-cellular-01.txt".
	
NOTE:	The mail server at ietf.org can return the document in
	MIME-encoded form by using the "mpack" utility.  To use this
	feature, insert the command "ENCODING mime" before the "FILE"
	command.  To decode the response(s), you will need "munpack" or
	a MIME-compliant mail reader.  Different MIME-compliant mail readers
	exhibit different behavior, especially when dealing with
	"multipart" MIME messages (i.e. documents which have been split
	up into multiple messages), so check your local documentation on
	how to manipulate these messages.
		
		
Below is the data which will enable a MIME compliant mail reader
implementation to automatically retrieve the ASCII version of the
Internet-Draft.

ftp://ftp.ietf.org/internet-drafts/draft-degermark-crtp-cellular-01.txt"><ftp://ftp.ietf.org/internet-drafts/draft-degermark-crtp-cellular-01.txt>