Trunked radio frequency communication system for accommodating both frequency and time division based RF communications
US5790527A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 20, 1994 |
| Grant date | Aug 4, 1998 |
| Priority date | — |
| Expiry date | Dec 20, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04W84/08
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
In a trunked radio communications system, apparatus and methods are provided for transparently updating existing frequency division multiple access (FDMA) communications facilities to accommodate time division multiple access (TDMA) communications. TDMA channels are added to existing FDMA sites on an individual basis to increase spectral efficiency and capacity while still being compatible with existing FDMA equipment and protocols. For example, the existing FDMA control channel and protocols are used by dual mode sites and dual mode radios. A dual mode radio transceiver selectively participates in trunked radio communications in either an FDMA mode or in a TDMA mode. Each dual mode radio includes a memory for storing a mode identifier identifying each channel as an FDMA or a TDMA working channel. When a channel assignment is made, the dual mode radio determines from that channel mode identifier stored in memory whether to operate in the FDMA or TDMA mode for that particular communication. Moreover, dual mode radios expedite synchronization to a TDMA working channel (time slot) using a timing relationship established between the FDMA control channel and the TDMA working channels. I…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.