CRTP over cellular radio links

Document Type Expired Internet-Draft (individual)
Authors Hans Hannu  , Lars-Erik Jonsson  , Krister Svanbro 
Last updated 1999-12-14
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


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.


Hans Hannu (
Lars-Erik Jonsson (
Krister Svanbro (

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)