Mobile communication system

• US 6,459,905 B1
• Filed: 07/07/1999
• Issued: 10/01/2002
• Est. Priority Date: 04/22/1998
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Fuji, Tsuyoshi
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): Green, Miguel D.
• Application Number:
  US09/341,275
• Time in Patent Office: 1,182 Days
• Field of Search: 455/7, 455/11.1, 455/12.1, 455/13.1, 455/15, 455/19, 455/20, 455/21, 455/427, 455/430, 455/552
• US Class Current: 455/552.1
• CPC Class Codes: H04B 1/005 adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges
• CPC Class Codes: H04B 1/006 using switches for selecting the desired band H04B1/0057 takes precedence
• CPC Class Codes: H04B 1/406 with more than one transmission mode, e.g. analog and digital modes
• CPC Class Codes: H04B 7/18536 Shadowing compensation therefor, e.g. by using an additional terrestrial relay
• CPC Class Codes: H04B 7/18563 Arrangements for interconnecting multiple systems data switching networks H04L12/00

Abstract

A mobile communication system with a portable telephone capable of automatically switching between a ground communication system and a satellite communication system, in which when the ground satellite system is not available and the portable telephone is in a place where a satellite from the satellite communication system cannot be observed, a signal process operation is switched in such a manner that an RF signal is processed by the ground communication system, and both of an IF signal and a baseband signal are processed by the satellite communication system; and a relaying apparatus for performing a converting operation of the RF signal in the satellite communication system and the RF signal in the ground communication system. The ground communication system and the satellite communication system can be automatically switched to be used without replacing the antenna/radio frequency units. Also, when the satellite communication system is utilized in an indoor area, the structure of the relaying apparatus can be simplified.

Claims

1. A mobile communication system comprising:

a ground communication system, said ground communication system including a radio interface;

a satellite communication system, said satellite communication system including a radio interface, said satellite communication system communicating with at least one satellite;

a relaying apparatus for converting an RF signal in the satellite communication system into an RF signal in the ground communication system;

a portable telephone;

said portable telephone automatically switching between said ground communication system and said satellite communication system, wherein;

while said ground communication system is not available; and

said portable telephone is in a place where said satellite of said satellite communication system cannot be observed;

a signal process operation, said signal process operation being switched in such a manner that;

an RF signal from said satellite communication system is converted by said relay apparatus into an RF signal in said ground communication system, and is processed by said ground communication system, and both of an IF signal and a baseband signal are processed by said satellite communication system; and

wherein said portable telephone includes;

a commonly-used antenna for transmitting/receiving the signal of said ground communication system and also the signal of said satellite communication system;

a duplexer connected to said commonly-used antenna, for duplexing transmission/reception signals;

a first switch for switching an output of said duplexer;

a satellite system receiving radio frequency unit connected to said first switch;

a ground system receiving radio frequency unit connected to said first switch;

a second switch connected to said satellite system receiving radio frequency unit and to said ground system receiving radio frequency unit;

a receiving IF circuit connected to said second switch;

a demodulator for demodulating an output of said receiving IF circuit;

a baseband processing unit into which the demodulation output of said demodulator is entered;

a modulator for modulating an output of said baseband processing unit;

a transmitting IF circuit connected to said modulator;

a synthesizer for supplying a local signal to said receiving IF circuit and to said transmitting IF circuit;

a third switch connected to said transmitting IF circuit;

a satellite system transmitting radio frequency unit connected to said third switch;

a ground system transmitting radio frequency unit connected to said third switch;

a fourth switch connected to said satellite system transmitting radio frequency unit and to said ground system transmitting radio frequency unit, whose output is supplied to said duplexer; and

a CPU for controlling said first, second, third, and fourth switches in such a manner that the first and second switches are controlled so as to connect said ground system receiving radio frequency unit and said ground system transmitting radio frequency unit in response to a first control signal;

said synthesizer produces a local signal suitably used to convert said ground system RF signal into an IF signal in response to a second control signal; and

said demodulator and said modulator are controlled so as to be operable by the modulating/demodulating methods of said satellite communication system in response to a third control signal.

2. A mobile communication system comprising:

a portable telephone including;

a commonly-used antenna for transmitting/receiving a signal of a ground communication system and also a signal of a satellite communication system;

a duplexer connected to said commonly-used antenna, for duplexing transmission/reception signals;

a first switch for switching an output of said commonly-used antenna;

a satellite system receiving radio frequency unit connected to said first switch;

a ground system receiving radio frequency unit connected to said first switch;

a second switch connected to said satellite system receiving radio frequency unit and to said ground system receiving radio frequency unit;

a receiving IF circuit connected to said second switch;

a demodulator for demodulating an output of said receiving IF circuit;

a baseband processing unit into which the demodulation output of said demodulator is entered;

a modulator for modulating an output of said baseband processing unit;

a transmitting IF circuit connected to said modulator;

a synthesizer for supplying a local signal to said receiving IF circuit and said transmitting IF circuit;

a third switch connected to said transmitting IF circuit;

a satellite system transmitting radio frequency unit connected to said third switch;

a ground system transmitting radio frequency unit connected to said third switch;

a fourth switch connected to said satellite system transmitting radio frequency unit and said ground system transmitting radio frequency unit, whose output is supplied to said duplexer; and

a CPU for controlling said first, second, third, and fourth switches in the case that while said satellite system is not available at said place where the satellite of said satellite communication system cannot be observed, the radio interface of said ground communication system is different from the radio interface of said satellite communication system, in such a manner that said ground system receiving radio frequency unit is connected to said ground system transmitting radio frequency unit in response to a first control signal;

said synthesizer produces a local signal suitably used to convert said ground system RF signal into an IF signal in response to a second control signal; and

said demodulator and said modulator are controlled so as to be operable by the modulating/demodulating methods of said satellite communication system in response to a third control signal.