Telecommunications – Carrier wave repeater or relay system – Portable or mobile repeater
Reexamination Certificate
1999-08-26
2001-11-27
Hunter, Daniel (Department: 2684)
Telecommunications
Carrier wave repeater or relay system
Portable or mobile repeater
C455S098000, C455S575100
Reexamination Certificate
active
06324380
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to commonly termed mobile satellite communication units utilizing satellites orbiting around the earth as network switching nodes and, more particularly, to dual mode mobile satellite communication units, which can be used as mobile terrestrial communication unit for cellular or PHS communication systems utilizing terrestrial radio stations as well as the mobile satellite communication unit.
PRIOR ART
As an example of mobile satellite communication system, an iridium plan communication system of Motoroller Inc. in U.S.A. is well known in the art.
FIG. 11
depicts the iridium plan communication system, which is shown in, for instance, Japanese Laid-Open Patent Publication No. 6-181456. A constellation
100
consists of, for instance, 66 satellites 200 moving along relatively low level orbits around the earth (not shown). Line-of-sight communication may be made from given points on the earth's surface with an obstructed view to one or more satellites. The constellation and the satellites which are moving along relatively low level orbits, are always moving relative to the earth. For example, a satellite moving along an orbit 765 km apart from the earth, is moving at a speed of about 25,000 km relative to an earth's surface point. This satellite is in the visual field of the earth surface's point for a period of at most about 9 minutes.
At every area or country on the earth's surface, a number of switching offices (SO)
101
are provided for data communication with satellites among adjacent ones of them via r-f trunking communication links
102
. The satellites are also doing data communication with one another via trunking communication links.
A switching office
101
in any area on the earth can control communication (or calls) sent out to given points via the constellation
100
. Each switching office
101
is coupled to a usual phone switching network (PSTN)
103
via a number of PSTN lines, and also can receive calls sent out from PSTN lines to mobile satellite communication line subscribers
104
. The PSTN lines
103
can send out calls transmitted from the mobile satellite communication line subscribers
104
.
As many as several million mobile satellite communication units MU are coupled to each mobile satellite communication line. The mobile satellite communication units MU can do communication at any place in an earth area covered by the mobile satellite communication network.
FIG. 12
shows a personal handyphone system (PHS) mobile communication system pertaining to the present invention (which is shown in, for instance, Japanese Laid-Open Patent Publication No. 7-187866). The system comprises a PHS control center
140
for storing position data, a plurality of relay stations
132
each wired via a digital switching office
131
and a common line signal network
130
to the PHS control center
140
, and a plurality of base stations
120
wired to each of the relay stations
132
. The relay stations
132
produces position data on the basis of position registration requests sent out from the base stations
120
.
In the position registration in such a system, a PHS unit
110
receiving position data notified from the pertinent base station
120
checks the data. When the data is different from position registration data stored in it, the PHS unit
110
sends out a position registration signal to the base station
120
in the radio zone (or position registration area
134
) in which the user is present. The position registration signal is relayed by the relay station
132
and arrives at the PHS control center
140
in a converted form necessary for switching. The present position data of the PHS unit
110
is thus stored in the PHS control center
140
. The above operation is executed whenever the position registration area
134
is changed by movement of the PHS unit
110
.
When the number of the PHS unit
110
is dialed from a general subscriber phone, the transmission side digital switching office
131
interrogates the PHS control center
140
via the common line signal network
130
about the position registration area
134
in which the PHS unit
110
of the dialed number is present, i.e., about position registration data necessary for switching. On the basis of this position registration data, tracing connection is made, and the base stations
120
in the pertinent position registration area
134
make a general terrestrial radio wave calling.
When a PHS unit
110
dials a general subscriber phone number, the subscriber certification data number of the PHS unit
110
is transmittedd together with the phone number via the base station
120
to the relay station
132
. The relay station
132
identifies the PHS unit
110
and confirms that the transmitter is a subscriber. Then, a line concerning the general subscriber phone is connected.
As is seen from the above description of the prior art, the mobile satellite communication unit is capable of making communication at any place on the earth under the mobile satellite communication network. A problem, however, is posed that high power is necessary for electromagnetic waves to reach the constellation which is utilized as network switching nodes, because the constellation is disposed along orbits spaced apart by 765 km from the earth.
In the mobile satellite communication unit, therefore, not only the transmitting circuit but also the battery power supply are inevitably large in size. Consequently, the unit requires high communication cost and much battery consumption, and also its frame has a large size. That is, a large size frame should always be carried as the mobile satellite communication unit. Unlike the case of carrying a recent small size unit, this is a great weight burden on the user.
The mobile terrestrial communication unit for the PHS or cellular system, on the other hand, in spite of its restriction that it permits communication in only prescribed areas, is for communication by transmitting and receiving data to and from a base station close to it. Thus, unlike the mobile satellite communication unit, the transmitting circuit and the battery power supply of the unit are small in size, and also the unit requires low communication cost and little battery consumption.
An advantageous mobile satellite communication unit is a duel mode one, which can provide the functions of both the units, i.e., those of the mobile satellite communication unit and the mobile terrestrial communication unit. Such a dual mode unit, however, is large in size and heavy in weight. Nevertheless, it should always be carried even by the user who uses the sole mobile terrestrial communication unit function (i.e., utilizes the sole cellular system of PHS services). This is a great weight burden on the user compared to the case of carrying the recent small size cellular system or PHS unit.
A further problem is that for mobile satellite communication which covers the whole globe, it is necessary to use different dual mode units in correspondence to different mobile terrestrial communication units depending on areas where the units are sold and used. To solve this problem, units in which a terrestrial communication function cartridge (including a ratio section, communication system control programs and a data memory) can be detachably inserted, have been investigated. Such units, however, again dictate carrying a large unit frame.
SUMMARY OF THE INVENTION
The present invention, in view of the above technical problems, has an object of providing a dual mode mobile satellite communication unit, which requires as low communication cost and as little battery power as possible, neither requires always carrying a large size unit frame nor necessitates user's great weight burden.
Another object of the present invention is to provide a mobile satellite communication unit, which can be readily carried and permits volume reduction.
The above and other objects of the present invention will become clear from the following description of the present invention.
In solving the prob
Kiuchi Kazuya
Masuda Yuzuru
Nagamachi Kazuo
Ookita Hideto
Sasaki Yoshio
Hunter Daniel
Kyocera Corporation
Nguyen Thuan T.
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