Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1997-06-06
2002-04-16
Vo, Nguyen T. (Department: 2682)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S434000, C455S552100
Reexamination Certificate
active
06374106
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a radio communication system searching method for a portable telephone terminal for selecting, when a plurality of radio communication systems having different carrier frequencies are present in a same area, a suitable one of the radio communication systems.
In radio communication systems for portable telephone terminals (including mobile telephone terminals) of the AMPS (Advanced Mobile Phone System) system adopted in North America, Australia and so forth, normally two different types of radio communication systems having different carrier frequencies are used in a same area so that various services by the two systems are available in the area. The two types of radio communication systems are generally classified from each other and managed depending upon whether the enterprise which makes the body of management is a radio company or a main line company. In the following description, a radio communication system managed by a radio company will be hereinafter referred to as a radio company system, and a radio communication system managed by a main line company will be hereinafter referred to as a main line company system.
The two types of systems will be described in detail below with reference to FIG.
6
. In
FIG. 6
, a radio company system is arranged in each of areas defined by broken lines while a main line company system is arranged in each of areas defined by solid lines. In particular, a radio company system managed by a company A is arranged in an area
101
; a main line company system managed by another company B is arranged in another area
102
which is a substantially same area as the area
101
; another radio company system managed by the company A is arranged in a further area
103
which is different and spaced away from the area
101
; another main line company system managed by a further company C is arranged in a still further area
104
which is a substantially same area as the area
103
; a further radio company system managed by a still further company D is arranged in a yet further area
105
which is different and spaced away from the areas
101
and
103
; and a further main line company system managed by a yet further company E is arranged in a yet further area
106
which is a substantially same area as the area
105
.
When the systems are managed in such a manner as shown in
FIG. 6
, if a particular user of a portable telephone terminal executes a contract with the radio company system managed by the company A in the area
101
, then the radio company system arranged in the area
101
makes a home system to the portable telephone terminal user. While the main line company system arranged in the substantially same area
102
and managed by the company B is present in the area
101
since the main line company system of the company B is a system outside of the contract to the user who is under contract with the radio company system of the company A, naturally the charge for usage of the main line company system is rather high.
By the way, when the user which is under contract with the radio company system of the company A in the area
101
moves from within the area
101
to any one of the other areas
103
to
106
, any one of these systems is outside the contract to the user. However, it is supposed that, as seen from
FIG. 6
, there may possibly be the same company as the particular company which manages the radio company system with which the user is under contract such as, for example, the company A which manages the radio company system in the area
103
, or an affiliated company of the particular company such as, for example, the company D which manages the radio company system in the area
105
.
While the system which is managed by such company is not the home system to the user, the user can use the system at a rather lower charge than the charge in ordinary roaming (to access a system other than the system with which the user is under contract, that is, a main line company system when the user is under contract with a radio company system, or a radio company system when the user is under contract with a main line company system). Also the charge system for users under contract with a main line company system is substantially similar to that for the user of the radio company system described above.
Accordingly, where the management areas of the systems are constructed as seen in
FIG. 6
, a portable telephone terminal of a user under contract with a radio company system is only required to have a function of preferentially searching a radio company system or of searching only a radio company system while a telephone terminal of another user under contract with a main line company system is only required to have a function of preferentially searching a main line company system or of searching only a main line company system.
In short, since the management area configuration of the systems is systematic as seen from
FIG. 6
, a portable telephone terminal is only required to preferentially search a radio communication system as with which the user is under contract or of searching only such radio communication system can be set by operation of the user itself (for example, by operation of keys). More specifically, if setting for preferentially searching a radio communication system with which the user is under contract is performed once, then a system favorable to the user can always be selected without modifying the setting once more.
In recent years, however, as the demand for portable telephones increases, the utilization areas of radio communication systems expand and also the number of radio communication systems continues to increase. Also excessive competition among radio communication systems is increasing.
Also, due to an influence of such expansion and increase of and excessive competition among radio communication systems, the classification of radio communication systems between a radio company system and a main line company system is disordered, and such a form (refer to
FIG. 7
which will be hereinafter described) that a same enterprise manages, in an area, a radio communication system of the same carrier frequency as that of the radio company system described above, but manages, in another area, another radio communication system of the same carrier frequency as that of the main line company system described above occurs. The function of searching a radio communication system provided for conventional telephone terminals cannot cope with the situation.
Therefore, it is desired that, while a user itself understands the arrangement of radio communication systems, it can make use of a function of selecting a portable telephone terminal to set and modify criteria for a search in accordance with a position wherein the portable telephone terminal is used.
Further, if radio communication systems of the same company type are employed in adjacent areas, then three or more radio communication systems may be present as a result of overlapping of such systems in a region in which only two radio communication systems have been present till then.
In such a situation just described, since a portable telephone terminal of the AMPS specification preferentially searches and accesses a radio communication system which is highest in intensity in radio waves (electric field), depending upon the condition of the radio waves, the user may not possibly access a radio communication system best to the user (in short, a radio communication system which is the most advantageous to the user in terms of the charge for using). In the worst case, even if the user is in the area under contract (at home), it cannot access even the home system.
For example, the situation wherein radio communication systems of the same company type are present in adjacent areas and a same enterprise manages radio communication systems of different company types and the situation wherein a user cannot access its home system while it is in an area of the home system will be described in more detail with reference to FIG.
7
. I
Hanawa Tetsuya
Konno Masahiro
Fujitsu Limited
Staas & Halsey , LLP
Vo Nguyen T.
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