Browse Prior Art Database

Poll Actuated Multiple Access Technique for Broadgathering Systems

IP.com Disclosure Number: IPCOM000039407D
Original Publication Date: 1987-Jun-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 6 page(s) / 74K

Publishing Venue

IBM

Related People

Calo, SB: AUTHOR [+2]

Abstract

A communications system design is proposed for supporting very large numbers of devices whose transmission requirements focus predominantly on a central reception facility. Each-to-every logical connectivity can be provided by store-and-forward switching from the central site. The system is composed of the interconnection of Poll Actuated Multiple Access (PAMA) Network Segments, which operate as independent local subnetworks and may also serve as store-and-forward elements for traffic from other subnetworks. The multiple access technique employed for each segment consists essentially of a poll actuated TDMA mechanism incorporating a dynamically variable, load-determined frame duration. It permits a great deal of flexibility while remaining relatively simple.

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Poll Actuated Multiple Access Technique for Broadgathering Systems

A communications system design is proposed for supporting very large numbers of devices whose transmission requirements focus predominantly on a central reception facility. Each-to-every logical connectivity can be provided by store-and-forward switching from the central site. The system is composed of the interconnection of Poll Actuated Multiple Access (PAMA) Network Segments, which operate as independent local subnetworks and may also serve as store-and-forward elements for traffic from other subnetworks. The multiple access technique employed for each segment consists essentially of a poll actuated TDMA mechanism incorporating a dynamically variable, load-determined frame duration. It permits a great deal of flexibility while remaining relatively simple. Introduction Methods of effectively dealing with the problems associated with the sharing of telecommunications resources by a very large number of geographically dispersed devices attempting to communicate with a central facility are considered. Such "broadgathering" problems arise,

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for example, in attempting to provide two-way interactive communications capabilities in environments, such as those encountered in commercial CATV systems, which were primarily designed to support broadcast transmissions from a single source to a very large number of terminal devices. The requirement that access be provided for terminal devices that are widely dispersed makes the direct application of propagation delay sensitive multiple access schemes like CSMA/CD inappropriate. Other mechanisms developed for local area networks are likewise not directly applicable because of limitations on the number of devices that can be supported, dependence on specific topologies of limited extent, or poor general performance. Further requirements that must be met include simplicity, flexibility, and the ability to provide relatively high rate communications (with respect to services commonly available via the telephone network) at a reasonable level of performance. Simplicity and flexibility are important because of the impact on cost and systems management complexity of the very large numbers of terminal devices that the system must be able to support. The approach proposed consists of a tree-structured interconnection of network segments, each of which operates independently as a local subnetwork while serving as a store-and-forward element for traffic from other subnetworks. The multiple access mechanism employed by the terminal devices attached to any particular segment is constructed in such a way as to naturally combine these two functionalities. The tree structure of the network was chosen in order to match the topology of existing CATV networks, and because it provides unambiguous paths for all connections, thus avoiding the complexities of having to make routing decisions in any of the network elements. Each Network...