US 4,901,307 A · Spread spectrum multiple access communication system using satellite or terrestrial repeaters

Abstract

A multiple access, spread spectrum communication system and method for providing high capacity communications to, from, or between a plurality of system users, using code-division-spread-spectrum communication signals. The communication system uses means for providing marginal isolation between user communication signals. The marginal isolation is provided by generating simultaneous multiple steerable beams; using an omni-directional antenna with polarization enhancement; using power control devices to adjust the output power for user generated communication signals either in response to their input activity level, or in accordance with a minimum allowable power for maintaining a communication link. The communication system can also employ a means for transmitting a predetermined pilot chip sequence contiguous with the code-division-spread-spectrum communication signals. In further embodiments the communication system employs a plurality of user terminals linked to each other or to other services through one or more terrestrial or satellite repeaters. Multiple satellite repeaters are operable in a new communication mode to obtain further gains in signal isolation.

Claims46

Dependent claims

A multiple access, spread spectrum communication system, comprising:

means for communicating information signals between at least two of a plurality of system users using code-division-spread-spectrum communication signals;
isolation means, coupled to said means for communicating, for unequally weighting signal power of said code-division-spread-spectrum communication signals, wherein said isolation means comprises:
activity detection means for measuring signal activity levels for said information signals relative to a no activity level over a predetermined sampling time and for providing an activity signal corresponding to measured activity;
and
power control means coupled to said means for communicating for adjusting a transmission power duty cycle for said code-division-spread-spectrum communication signals in response to changes in said activity signal.

2 more elements

A multiple access, spread spectrum communication system, comprising:

means for communicating information signals between at least two of a plurality of system users using code-division-spread-spectrum communication signals;
isolation means, coupled to said means for communication, for unequally weighting signal power of said code-division-spread-spectrum communication signals;
and
wherein said means for communicating further comprises:
chip generation means for generating a plurality of quasi-orthogonal spreading functions;
code selection means for assigning one of said spreading functions to a user;
a plurality of mobile user terminals capable of transmitting and receiving said code-division-spread-spectrum communication signals, each of said user terminals comprising:
transmission means for generating a code-division-spread-spectrum communication signal in response to an input information signal according to an assigned spreading function;
receiver means for generating an output information signal by processing a received code-division-spread-spectrum communication signal according to said assigned spreading function;
and
at least one omni-directional antenna coupled to said transmission means and said receiver means;
and
at least one repeater means for receiving code-division-spread-spectrum communication signals from said plurality of user terminals and for translating said code-division-spread-spectrum communication signals to form suitable for transfer to an intended recipient user.

10 more elements

A multiple access, spread spectrum communication system, comprising:

means for communicating information signals between at least two system users using code-division-spread-spectrum communication signals, said means for communicating comprising:
chip generation means for generating a plurality of quasi-orthogonal spreading functions;
code selection means for assigning at least one of said spreading functions to a system user;
a plurality of mobile user terminals capable of transmitting and receiving said code-division-spread-spectrum communication signals, each of said user terminals comprising:
transmission means for generating a code-division-spread-spectrum communication in response to an input information signal according to said assigned spreading function;
and
receiver means for generating an output information signal by processing a code-division-spread-spectrum communication signal according to said assigned spreading function;
said receiver having a demodular, comprising:
input means for receiving code-division-spread-spectrum communication signals;
a variable frequency source generating a local reference signal of predetermined frequency;
a radio frequency mixer connected to said input means and said variable frequency source for the code-division-spread-spectrum communication signals with the local reference signal to provide an intermediate spread spectrum signal;
filter means connected in series with said radio frequency mixer for filtering undesirable frequency components from said intermediate spread spectrum signal;
phase division means connected in series with said filter means for dividing said spread spectrum signal into an analog in-phase signal and an analog quadrature signal;
converter means connected to said phase division means for converting said analog incident and quadrature signals to digital incident and quadrature signals at a variable rate;
combiner means connected to an output of said converter means for juxtaposing said digital in-phase and quadrature signals onto a single data line for transfer to other components within said demodulator in serial fashion;
pilot chip reference means for generating a local bit sequence corresponding to a predetermined pilot chip sequence transmitted contiguous with communication signals received by said demodulator, said local bit sequence being generated with a predetermined period;
carrier tracking means connected to said combiner means and said pilot reference means for comparing said local pilot chip sequence to received signals in a timed relationship to determine the timing of said code-division-spread-spectrum communication signals with respect to said local pilot chip sequence and for adjusting the frequency of said variable frequency source;
chip synchronization means connected to said combiner means and said pilot reference means for comparing said local pilot chip sequency to received signals in a plurality of timed relationships to determine the timing of said code-division-spread-spectrum communication signals with respect to said local pilot chip sequence and for adjusting the rate for said converter means;
unit chip means for generating a bit sequence corresponding to said assigned spreading function;
despreading means connected to said combiner and said unit chip means for generating despread-spectrum in-phase and quadrature information signals;
output means connected to said despreading means for combining said despread-spectrum quadrature and in-phase signals into an output information signal;
at least one omni-directional antenna;
and
at least one repeater means for receiving code-division-spread-spectrum communication signals from said plurality of user terminals and translating said code-division-spread-spectrum communication signals to a form for transfer to an intended recipient user.

21 more elements

In a spread spectrum multiple access communication system in which system users communicate user addressable information signals using address corresponding code-division-spread-spectrum communication signals wherein with respect to communications between at least two system users other system users generate mutual interference by contemporaneously communicating code-division-spread-spectrum communication signals with said system having a processing gain for reducing mutual interference, in said communication system a method for providing high system user capacity by further reducing mutual interference in communications between said at least two system users comprising the steps of:

providing a plurality of system user addressable narrow band information signals;
converting said plurality of system user addressable narrow band information signals into a corresponding plurality of system user address corresponding wide band code-division-spread-spectrum communication signals;
transmitting said plurality of code-division-spread-spectrum communication signals between system users;
receiving, at each respective system user, system user address corresponding code-division-spread-spectrum communication signals and other respective system user addressed code-division-spread-spectrum communication signals as mutual interference;
providing for each respective system user an increase in system user realized average signal power for said system user address corresponding code-division-spread-spectrum communication signals with respect to mutual interference signal power of said other system user address corresponding code-division-spread-spectrum communication signals;
and
converting, at each respective system user, received address corresponding code-division-spread-spectrum communication signals into corresponding user addressable information signals.

4 more elements

Dependencies are inferred from the claim text.

Spread spectrum multiple access communication system using satellite or terrestrial repeaters

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Spread spectrum multiple access communication system using satellite or terrestrial repeaters

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Abstract

Claims46