Compatible licensed and unlicensed band portable handset unit for TDMA wireless communications system
US5475677A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 29, 1994 |
| Grant date | Dec 12, 1995 |
| Priority date | — |
| Expiry date | Dec 29, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04W88/02
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
In a TDM/TDMA portable radio communications system, a portable handset is compatible for operation in both a frequency-division duplexing (FDD) mode for communication in the licensed portion of the Emerging Technologies frequency band, and in a time-division duplexing (TDD) mode for communication in the unlicensed portion of the Emerging Technologies frequency band. In the FDD mode, different frequencies are used to separate a downlink transmission to a portable from a port from an uplink transmission from a port to a portable. In the TDD mode, uplink and downlink transmissions are separated in different time-slots, but at the same frequency. The handset includes common transmit and receive circuitry that operates at fixed IF frequencies that are separated in frequency by the fixed FDD frequency difference between corresponding uplink and downlink signals. In the FDD mode, therefore, a frequency synthesizer (301), which is used to tune to transmit and receive at different frequencies from different ports, does not have to switch its frequency between transmitting and receiving a burst to and from a single port. In the TDD mode, however, even though uplink and downlink signals are a…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.