RFC 3322 (rfc3322) - Page 2 of 13
Signaling Compression (SigComp) Requirements & Assumptions
Alternative Format: Original Text Document
RFC 3322 SigComp Requirements & Assumptions January 2003
1. Introduction
In wireless environments, and especially in cellular systems, such as
GSM/GPRS, there is a need to maximize the transport efficiency of
data over the radio interface. The radio spectrum is rather
expensive and must be carefully used. Therefore, the cellular
systems must support a sufficient number of users to make them
economically feasible. Thus, there is a limitation in the per user
bandwidth.
Compressing the headers of the network and transport protocols used
for carrying user data is one way to make more efficient use of the
scarce radio resources [ROHC]. However, compression of the messages
from signaling protocols, such as SIP/SDP, should also be considered
to increase the radio resource usage even further. Compression will
also improve the service quality by reducing the user idle time at
e.g., call setup. When IP is used end-to-end, new applications, such
as streaming, will be brought to tiny end-hosts, such as cellular
devices. This will introduce additional traffic in cellular systems.
Compression of signaling messages, such as RTSP [RTSP], should also
be considered to improve both the service availability and quality.
New services with their corresponding signaling protocols make it
reasonable to consider a scheme that is generic. The scheme should
be generic in the meaning that the scheme can efficiently be applied
to arbitrary protocols with certain characteristics, such as the
ASCII based protocols SIP and RTSP.
1.1. Protocol Characteristics
The following application signaling protocols are examples of
protocols that are expected to be commonly used in the future. Some
of their characteristics are described below.
1.1.1 SIP
The Session Initiation Protocol [SIP] is an application layer
protocol for establishing, modifying and terminating multimedia
sessions or calls. These sessions include Internet multimedia
conferences, Internet telephony and similar applications. SIP can be
used over either TCP [TCP] or UDP [UDP]. SIP is a text based
protocol, using ISO 10646 in UTF-8 encoding.
Hannu Informational