System for short range wireless data communication to inexpensive endpoints
US6177861A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 17, 1998 |
| Grant date | Jan 23, 2001 |
| Priority date | — |
| Expiry date | Jul 17, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K7/0008
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A system provides short range wireless data communication from a central control point (e.g., interrogator) to inexpensive endpoints (e.g., tags). The endpoints utilize the technology of modulated backscatter for transmission from the tags to the interrogator. The system uses a new downlink protocol for data transmission from the interrogator to the tags and a new uplink protocol for data transmission from the tags to the interrogator. Both protocols use a backoff/retry algorithm to randomly retransmit any non-acknowledged messages. System capacity from the tags to the interrogator is further enhanced by the use of uplink subcarrier frequency division multiplexing.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.