Multiple access digital communications system
US4210780A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 27, 1978 |
| Grant date | Jul 1, 1980 |
| Priority date | — |
| Expiry date | Mar 27, 1998 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L12/40032
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
An unslotted radio frequency multiple access bus communications system employing a contention listen-while-talk (LWT) protocol. The system includes a plurality of remotely located terminals coupled to a communications bus. The bus includes a pair of oppositely directed, unidirectional signal paths which are connected at one end so that one path is an inbound path to that end and the second is an outbound path from that end. Each of the remote terminals includes a bus interface unit (BIU) coupled to both the inbound and outbound paths at the remote location. Each BIU is adapted to transmit and receive modulated carrier signals on the inbound and outbound paths, respectively. When a terminal wishes to send a message to another terminal, the terminal's BIU initially performs an rf carrier sensing operation to make an initial determination as to whether or not any other subscriber is transmitting on the inbound path. In the event no carrier is detected, the BIU confirms this determination by first beginning to transmit a message packet modulated on a carrier signal and addressed to the desired receiving terminal on the inbound path, and then monitoring the outbound path during a collis…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.