Multiplex communications – Wide area network – Packet switching
Patent
1994-12-29
1995-12-12
Hsu, Alpus
Multiplex communications
Wide area network
Packet switching
370 30, 370 50, 370 691, 370 953, 379 58, 455 342, 455 89, H04B 156, H04J 400, H04L 514
Patent
active
054756774
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 at the same frequency, the synthesizer is switched in frequency between transmitting uplink and receiving downlink.
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Arnold Hamilton W.
Chang Li F.
Noerpel Anthony R.
Sollenberger Nelson R.
Ziegler Robert A.
Bell Communications Research Inc.
Falk James W.
Hsu Alpus
Suchyta Leonard Charles
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