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

From: [email-masked]
Date: Wed, 15 Dec 1999 06:55:00 -0500

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.

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