Browse Prior Art Database

An Improved Collision Resolution Method for Multiple Access Protocols

IP.com Disclosure Number: IPCOM000103243D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 47K

Publishing Venue

IBM

Related People

Cheng, TD: AUTHOR [+3]

Abstract

Described in this disclosure is a method to improve the efficiency of collision resolution in the ALOHA and CSMA multiple access protocols. It is based on the following simple observation:

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This is the abbreviated version, containing approximately 81% of the total text.

An Improved Collision Resolution Method for Multiple Access Protocols

      Described in this disclosure is a method to improve the
efficiency of collision resolution in the ALOHA and CSMA multiple
access protocols.  It is based on the following simple observation:

      In the event of a collision, the first few bytes of at least
one of the packets involved in the collision is very likely to come
through unscathed, and these bytes contain the packet header and the
source address.  Knowing the structure of a packet, nodes may compare
the source address field of the collided packet with their own
address.  A station that finds a match between the source address in
the packet and its own address immediately retransmits its message.
Stations that do not find such a match go through a normal collision
resolution phase (such as exponential backoff).  By doing so, the
probability of a subsequent collision involving the same packets is
greatly decreased. In the event that the colliding packets are
completely destroyed, all the nodes involved in the collision execute
their normal collision resolution algorithm.  Note that no problem
arises if the collision modifies one of the source address fields to
another valid address.  If the station at that address was involved
in the collision, it simply transmits its message first, and the
remaining nodes transmit later.  In the event of a collision that
modifies the source address field in such a way that two or more
nodes...