Method and apparatus for detecting the collision of data packets
US4885743A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 18, 1988 |
| Grant date | Dec 5, 1989 |
| Priority date | — |
| Expiry date | Feb 18, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L12/413
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
Through the method and apparatus of the present invention the collision of two packets can be detected under a variety of conditions. The preamble of each packet transmitted is modified to include collision detection data comprising an initial pulse having an amplitude sufficiently high to be detected even when attenuated and having a pulse width twice the normal data pulse width followed by a randomly generated code of a predetermined length in which a predetermined number of pulses of the code are at a high binary data signal level. Thus, in the event two packets collide, the collision may be detected by detecting a second large pulse within a time period less than the sum of the packet duration and the gap, by determining if a large initial pulse has a pulse width larger than the generated pulse width, by determining if a subsequent large pulse occurs within the remainder of the packet and by determining if more than the predetermined number of pulses of the code have a high binary data level.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.