Multiplex communications – Communication over free space – Combining or distributing information via code word channels...
Reexamination Certificate
1998-07-17
2001-04-10
Vu, Huy D. (Department: 2663)
Multiplex communications
Communication over free space
Combining or distributing information via code word channels...
C370S517000, C370S320000
Reexamination Certificate
active
06215780
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to wireless communication systems and, more particularly, to code division multiplexed communication systems.
BACKGROUND OF THE INVENTION
In a code division multiplexed communication system, an information signal, typically in digital form, is multiplied by a unique pseudonoise code, upconverted to a carrier frequency, and transmitted from a subscriber unit to a receiving station. Generally, the bandwidth of the pseudonoise code is much greater than the bandwidth of the information signal. Thus, the effect of the multiplication of the information signal by the pseudonoise code is to greatly increase the bandwidth occupied by the product signal. Each subscriber unit using the code division multiplexed communication system is assigned a different unique pseudonoise code with all subscriber units sharing the same product signal bandwidth.
At a receiving end of the communication system, the signal is first received through an appropriate antenna and downconverted. The downconverted signal is correlated with the pseudonoise code assigned to the particular transmitting subscriber unit. During the correlation process, a product signal of the particular transmitting subscriber unit is separated from the signals of other transmitting subscriber units. The correlated output represents the signal from the particular transmitting subscriber unit. The cross-correlated outputs (e.g. signals from other transmitting subscriber units) are desirably minimized. By maximizing correlated outputs and minimizing cross-correlated outputs, the number of subscriber units which make use of the communication system is increased.
Therefore, what is needed are a method and system for minimizing the cross-correlated outputs of the correlator of a code division multiplexed communication system. What is also needed are a method and system for maximizing the correlated outputs of the correlator of a synchronizing the code division multiplexed communication system. What is also needed is a code division multiplexed communications system which has a greater capacity than conventional code division multiplexed systems.
REFERENCES:
patent: 5305468 (1994-04-01), Bruckert et al.
patent: 5363375 (1994-11-01), Chuang et al.
patent: 5383225 (1995-01-01), Aguirre et al.
patent: 5463400 (1995-10-01), Tayloe
patent: 5640386 (1997-06-01), Wiedeman
patent: 5666122 (1997-09-01), Carter
patent: 0827293 (1998-03-01), None
patent: 9515626 (1995-06-01), None
Emmons, Jr. Thomas Peter
Hogberg Shawn Wesley
Peters Robert Anthony
Startup James William
Bogacz Frank J.
Gorrie Gregory J.
Motorola Inc.
Vu Huy D.
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