Browse Prior Art Database

Channel Allocation in a Multi Terminal System

IP.com Disclosure Number: IPCOM000089807D
Original Publication Date: 1977-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Closs, F: AUTHOR [+4]

Abstract

In a system including a controller communicating with a plurality of terminals over an outbound channel (controller to terminals) and an inbound channel (terminals to controller), the inbound channel is allocated to one terminal at a time on a request basis. The following describes a method for organizing channel allocation and avoiding contention.

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Channel Allocation in a Multi Terminal System

In a system including a controller communicating with a plurality of terminals over an outbound channel (controller to terminals) and an inbound channel (terminals to controller), the inbound channel is allocated to one terminal at a time on a request basis. The following describes a method for organizing channel allocation and avoiding contention.

The controller transmits a continous polling sequence over the outbound channel, addressing terminals sequentially. When a terminal which is ready to send receives its address, it starts transmitting idle characters (e.g., zeros) on the inbound channel. As soon as the controller detects signal power (or, as an alternative, recognizes idle characters) on the inbound channel, it starts transmitting idle characters (e.g., zeros) instead of polling addresses on the outbound channel.

Any terminal ready to send, that started transmitting idle characters after receipt of its address, continues watching signals on the outbound channel.

- If it receives another address A(i + 1) after its own address A(i) (before the idle character sequence starts on the outbound channel), it was the first polled terminal that was ready to send, and then stops transmitting idle characters (if necessary after a given delay to avoid overlap) and starts transmitting its data.

- If it receives no further address after its own address A(i), i.e., if idle characters are received immediately after its own address, it was not the first polled terminal ready to send, and thus st...