Browse Prior Art Database

PROCEDURE FOR REDUCING TCP OVERHEAD ON WIRELESS LINKS

IP.com Disclosure Number: IPCOM000008603D
Original Publication Date: 1998-Mar-01
Included in the Prior Art Database: 2002-Jun-26
Document File: 4 page(s) / 240K

Publishing Venue

Motorola

Related People

John Hughes: AUTHOR

Abstract

A procedure is described which improves the efficiency of TCPilP over wireless links without any requirement to modify the applications TCPiIP stack. The procedure describes how it is possible through the use of a link layer air interface connection oriented protocol, to remove the need to transport the connection setup, connection termination and acknowledgement messages over the air interface and hence significantly reduce air interface traffic.

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MOTOROLA Technical Developments

8

PROCEDURE FOR REDUCING TCP OVERHEAD ON WIRELESS LINKS

by John Hughes

ABSTRACT

  A procedure is described which improves the efficiency of TCPilP over wireless links without any requirement to modify the applications TCPiIP stack. The procedure describes how it is possible through the use of a link layer air interface connection oriented protocol, to remove the need to transport the connection setup, connection termination and acknowledgement messages over the air interface and hence significantly reduce air interface traffic.

1. INTRODUCTION

  This document describes an efficient method for the transport of TCP/IP traffic over wireless band- width limited networks. It proposes a procedure which removes the need for transporting the three- way handshake at TCP connection set up and four- way handshake at TCP connection termination over the wireless link.

2. TCP PROCEDURES

TCP communication consists typically of three phases:

I. Connection establishment

2. Data transfer

3. Connection termination

  A typical connection establishment consists of the transmission of three TCP segments. The initiator (the client) of the connection sends a SYN segment requesting a connection with another TCP entity (the server). The server responds with its own SYN segment, including an acknowledgment. The client responds to the servers SYN segment with an acknowledgment-hence the three way handshake during connection establishment.

  Only once this three way handshake has completed may the client begin transmitting data. Data is tran- mitted in PSH segments. The server must respond with acknowledgments in the opposite direction.

  Connection termination involves the transmission of four segments. The client sends a FIN segment, which the server then acknowledges. The server then sends a FIN segment which the client acknowledges. The TCP connection has now been terminated.

  Hence TCP can be seen to introduce quite a significant amount of overhead especially for the transfer of small amounts of data. While this over- head resulting from connection establishment and connection termination may not be perceived as a large problem for TCP over wireline networks, the impact on a wireless network where bandwidth is less freely available can be considerable. It would therefore be desirable to provide a mechanism which could help reduce the overhead while at the same time ensuring that there is no disruption to the service offered to the end users.

  There are a number of proposals aimed at improving the efficiency of TCP over wireless links. There exists a proposal to provide extensions to TCP in order to improve support for transactions
i.e. short request-response type messages. Called TiTCP it proposes reducing the overhead of the three way handshake by means of a 32 bit option to be used as a TCP option, called a 'connection count' (CC). By applying CC values to each con- nection a server can overcome the need for a check to ensure that a...