Multiplex communications – Generalized orthogonal or special mathematical techniques – Fourier transform
Reexamination Certificate
1998-06-17
2001-02-06
Ton, Dang (Department: 2732)
Multiplex communications
Generalized orthogonal or special mathematical techniques
Fourier transform
Reexamination Certificate
active
06185182
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a power sharing amplifier system; and more particularly, related to a power sharing amplifier system for a cellular communication system.
2. Description of the Prior Art
FIG. 1A
shows an 8 by 8 cellular transmitter configuration generally indicated as
100
similar to that shown and described in U.S. patent application Ser. No. 08/683,735. The 8 by 8 cellular configuration
100
includes eight separate low power transmitters generally indicated
102
, an 8th order transform matrix circuit
104
, eight amplifiers generally indicated
106
, an 8 by 8 inverse transform matrix circuit
108
, and eight antennas generally indicated as
110
.
FIG. 1B
shows a mapping of each input port to a respective output port in the 8th order cellular configuration.
FIG. 1C
shows a chart of phase shifts for the 8th order transform matrix circuit
104
and the 8th order inverse transform matrix circuit
108
in the 8 by 8 cellular configuration.
When configured as shown, there is only one output (antenna) port for each input (low power transmitter) port, as shown in the mapping of FIG.
1
B.
The amplification sharing technique used in the 8 by 8 cellular configuration
100
offers some advantages over the amplification technique of the standard cellular configuration. For example, in the 8 by 8 cellular configuration
100
, the amplifiers
108
effectively share the amplification of all the input signals, which provide inherent redundancy in the overall amplification of the input signals. Thus, if one amplifier fails, then all sectors still operate and maintain communication between the subscriber and the land mobile radio system. In such a case, the 8 by 8 cellular configurations
100
may be operating in a less desirable operating mode, but nevertheless it still operates and allows additional time for the failed amplifier to be repaired or replaced. Moreover, the 8 by 8 cellular configuration
100
also uses fewer amplifiers than the standard cellular configuration if redundant amplifiers are maintained for each sector. These advantages combine to make the improved cellular configuration
100
less expensive and more reliable than the standard cellular configuration.
However, one disadvantage of the 8 by 8 cellular configuration
100
shown is that the amplification sharing technique results in intermodulation products between the eight input signals to the various amplifiers that distort the amplified RF output signal sent to and transmitted by the antenna
110
.
SUMMARY OF THE INVENTION
In its broadest sense, the present invention provides a power sharing amplifier system for a cellular communications system, having with an 8th order transform matrix circuit, eight power sharing amplifiers and an 8th order inverse transform matrix circuit.
The 8th order transform matrix circuit has six input ports that respond to six RF input signals and has eight output ports that provide 8th order transform matrix RF input signals. The 8th order transform matrix circuit also has two input ports that do not receive input signals, but instead are coupled through a resistor to ground.
The eight power sharing amplifiers respond to the 8th order transform matrix input signals and provide eight amplified transformed RF signals.
The 8th order inverse transform matrix circuit has eight input ports that responds to the eight amplified transformed signals, and has six output ports that provide six inverse transform amplified RF output signals to six output ports. The 8th order inverse transform matrix circuit also has two output ports that do not provide output signals to an antenna, but instead are coupled through a resistor to ground for dissipating intermodulation distortion products.
The present invention provides a new and unique power sharing amplifier system that reduces the undesirable effects of the intermodulation distortion products that result from the shared amplification technique.
Other objects of the invention will in part be apparent and will in part appear hereinafter.
Accordingly, the invention comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.
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Larkin Robert S.
Meredith Sheldon K.
Radio Frequency Systems Inc.
Ton Dang
Ware, Fressola, Van Der Sluy & Adolphson LLP
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