Browse Prior Art Database

Method for Efficient Use of Transit Data Channel to Allow Additional Classic Data Channel User Payload

IP.com Disclosure Number: IPCOM000167386D
Original Publication Date: 2008-Feb-11
Included in the Prior Art Database: 2008-Feb-11
Document File: 4 page(s) / 207K

Publishing Venue

Motorola

Related People

Yunhai Yang: INVENTOR [+2]

Abstract

IP Header Compression has been used in ASTRO25 Trunked Transit system to reduce the packet size over the air interface. Compression full header needs to be periodically refreshed. The transmission of full header requires using classic packet data channel instead of transit data channel, which is not an efficient method. This paper provides a method to interleaving full header subcomponents into transit data payload within a transit slot. It describes how a transport change can improve data transfer efficiency and capacity without degrading transmission reliability in an ASTRO25 Trunked Transit system.

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Method for Efficient Use of Transit Data Channel to Allow Additional Classic Data Channel User Payload

By Yunhai Yang, Yun Chen

Motorola, Inc.

Networks Business

 

ABSTRACT

IP Header Compression has been used in ASTRO25 Trunked Transit system to reduce the packet size over the air interface.  Compression full header needs to be periodically refreshed.  The transmission of full header requires using classic packet data channel instead of transit data channel, which is not an efficient method.  This paper provides a method to interleaving full header subcomponents into transit data payload within a transit slot.  It describes how a transport change can improve data transfer efficiency and capacity without degrading transmission reliability in an ASTRO25 Trunked Transit system. 

PROBLEM

In an ASTRO25 Trunked Integrated Voice & Data (IV&D) two-way radio system with the Transit feature, small size data is transmitted in a pre-defined Transit Slot over a Transit Packet Data Channel (PDCH).  If the data can’t fit into a Transit Slot, it is transmitted over a Classic IV&D PDCH.  Internet Protocol (IP) is chosen to carry the data as an IP payload.  RFC2507 UDP/IP header compression has been selected in the ASTRO 25 Transit System to fit a transit message into a Transit Slot for scheduled transmitting.  Since the compressed header does not provide full information, as a traditional IP header does, a Transit Mobile Subscriber Unit (MSU) needs to switch to Classic IV&D PDCH to send the “oversized” (can’t fit within a Transit Slot) Full IP Header Refresh.  RFC 2507 defines the periodic full header refresh method.  In most cases, the (UDP/IP Header Compression) Context that is used between a Transit MSU and a Packet Data Router (PDR) never changes after the first Context being established but the periodic method still requires the subscriber to switch back to Classical IV&D PDCH to send the full IP header.  In fact, the new full header is needed when a context is changed.

In a Transit System, frequent Full Header Refreshes will introduce a large amount of unnecessary Classic IV&D PDCH traffic and it will greatly impact the Channel Resource Utilizations that are critical for co-existing Active Public Safety Users in the system. It is this inefficient use of the IV&D PDCH channel that this disclosure aims to improve.

SOLUTION

To decrease the use of the Classic IV&D PDCH, the Non-Context-Changing Full Header Refreshes will be divided into smaller pieces and piggybacked into regular Transit Messages (messages that are transmitted with compressed header over Transit PDCH) as shown in Figure 1 below.  After receiving all of the Full Header Refresh piggyback components, the decompressor will reassemble the Full Header Refresh and update the Context.  The decompressor will discard the whole Full Header Refresh c...