Browse Prior Art Database

Retransmission Scheduling Mechanisms in an Interrupted Slotted-ALOHA Channel

IP.com Disclosure Number: IPCOM000111490D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Natarajan, KS: AUTHOR

Abstract

In an interrupted channel, such as that of a slow frequency-hopping spread-spectrum radio system, using slotted-ALOHA medium-access control, a mechanism is disclosed that permits backoff that persists beyond the interruption. This can occur either if the number of slots in the current hop is insufficient for the traffic load, or if the backoff computation for a given contender exceeds the highest slot number in the current hop.

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This is the abbreviated version, containing approximately 58% of the total text.

Retransmission Scheduling Mechanisms in an Interrupted Slotted-ALOHA
Channel

      In an interrupted channel, such as that of a slow
frequency-hopping spread-spectrum radio system, using slotted-ALOHA
medium-access control, a mechanism is disclosed that permits backoff
that persists beyond the interruption.  This can occur either if the
number of slots in the current hop is insufficient for the traffic
load, or if the backoff computation for a given contender exceeds the
highest slot number in the current hop.

      Interrupted communications channels abound in practice.  The
interruption is typically periodic, and may be because of a
physical-layer situation (e.g., frequency-hopping) or because the
channel is being time-shared between uses.  If there are multiple
users of the channel, a protocol is needed to coordinate their use.
This protocol is called a "medium-access" protocol.  In several
environments, including satellite radio systems, it is not practical
to obey a listen-before-send discipline, and in these environments a
medium-access protocol called slotted-ALOHA is often used.  But
slotted-ALOHA is defined for a non-interrupted channel.

      Disclosed is a generalization of slotted-ALOHA to account for
interrupted channels.  The procedure is as follows:

1.  It is assumed that the channel becomes available for use
    accompanied by a signal that indicates the number of slots
    available for the current, non-interrupted, period.

2.  C...