3GPP TSG-T2#4 / ETSI SMG4
Miami, US, 14-16 June 1999	TSGT2#4(99)505	

Agenda Item:	SWG3

Source:	One-2-One

Title:	Message delivery protocols

Document for:	Discussion

Summary

This short paper suggests that the existing messaging protocols as used universally in the IP (Internet) world should be the basis for the transfer of all types of message in 3G mobile networks.  SWG3 are invited to discuss the merits of this approach.

Messaging Protocols carried over TCP/IP

GPRS has been developed to offer a TCP service between a mobile and an application server in a fixed network.  It is assumed that this service will continue in 3G networks.  TCP in a packet environment provides a varying data delivery rate according to error conditions and network loading, but this is quite suitable for message delivery.

Messaging protocols used in the Internet have evolved over many years, starting with SMTP.  The present-day coding techniques can support a wide range of message types, from the simplest plain text message to a complex multi-part message containing coded data for any media, eg. graphics, sound clip, video clips, which can be contained within a single message.  The basic structure is very extendable to allow new application types or coding techniques to be introduced.  There is also scope to define application-specific header parameters if required.

The obvious benefit of adopting the existing protocols, where possible, is that they are well understood by many application developers, and will help facilitate the convergence of fixed-mobile communications.

3G Mobile Messaging

One of the earliest improvements in 3G compared to the existing SMS should be the support for longer messages.  The use of existing “off the shelf” TCP/IP based protocols can support the delivery of text messages having any length (in principle) using the simplest message coding.  (No need to worry about concatenated messages!).  As the capabilities of mobiles develop over time, the extensions to the basic protocol are ready to support the more advanced message types.

Additional Mobile Requirements

There are a number of SMS features which were developed for mobile applications, which would probably need to be added to the TCP/IP based protocols.  These include

Message waiting indicators
Message classes (for message handling)
Replace types
Return call
SIM data download
etc

It should be possible to accommodate all these requirements by the use of new message header parameters and/or application types and encoding types for the message sections.

Alerting

It is essential in the 3G mobile environment to have the equivalent of the SMS-Alert. Then, when a messaging server has been unable to deliver a message because the destination mobile was not reachable, the 3G network can inform the messaging server that the mobile has been in contact with the network, and the messaging server can attempt another delivery. This is the most significant feature that does not have an equivalent in the existing TCP/IP based protocols, and so it needs to be specified for 3GPP.

Centralised “In-box”

Where messaging services store messages in a centralised server, again it should be possible to use existing protocols, such as POP3 and IMAP, over a TCP connection to manage these messages.  Any message to be transferred to the mobile would be encoded using the existing techniques.