Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Reexamination Certificate
1998-07-08
2002-12-17
Nguyen, Chau (Department: 2739)
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
C370S347000
Reexamination Certificate
active
06496495
ABSTRACT:
BACKGROUND OF THE INVENTION
1, Field of the Invention
The present invention relates to a cellular communication system which comprises a host device, plural subordinate devices, and plural terminals and particularly, to the cellular communication system in which each terminal communicates with the host device through the subordinate device of which the terminal is placed in the service area.
2. Description of the Prior Art
FIG. 3
shows a block diagram showing a conventional cellular communication system. In
FIG. 3
, reference numeral
101
represents a host device which has four interfaces for communicating with subordinate devices. Reference numerals
102
,
103
,
104
, and
105
represent subordinate devices which are connected with host device
101
through dedicated lines
110
,
111
,
112
and
113
in a star configuration, respectively. Reference numerals
120
to
125
represent terminals which communicate with host device
101
through subordinate devices
102
to
105
.
The cellular communication system is one of data relay systems. In the cellular communication system, host device
101
dynamically assigns one of subordinate devices
102
to
105
to each of terminals
120
to
125
in order to keep communication quality best. For example, host device
101
gives terminal
120
the instruction to communicate through subordinate device
102
when terminal
120
is placed in the service area of subordinate device
102
. Host device
101
gives terminal
121
to
125
the similar instructions. Terminals
120
to
125
move across service areas of subordinate devices
102
to
105
. Therefore, the number of terminals which are in the service area of each of subordinate devices
102
to
105
fluctuates or the traffic of each of subordinate devices
102
to
105
fluctuates with the lapse of time. Moreover, the numbers of terminals which are in the service areas of subordinate devices
102
to
105
and, therefore, the traffics thereof, are uneven if subordinate devices
102
to
105
are not located at regular intervals. Consequently, the channel capacities of dedicated lines
110
to
113
were determined by the maximum number of terminals which gather in their respective service areas. Heretofore, dedicated lines
110
to
113
had the fixed channel capacities which were determined in such a way.
However, because the channel capacities of dedicated lines
110
to
113
were fixed while the traffics which pass through subordinate devices
102
to
105
are variable, unused channels or unused time slots increased when the traffics decreased. Thus, the channel capacities of dedicated lines
110
to
113
were not used effectively.
SUMMARY OF THE INVENTION
In order to overcome the aforementioned disadvantages, the present invention has been made.
An object of the present invention is to provide a cellular communication system in which a host device flexibly changes the channel capacities of lines in accordance with the traffics of subordinate devices, whereby the channel capacities of lines are effectively used even when the system is used under the condition that the traffics fluctuate or are uneven.
According to the invention, there is provided a cellular communication system in which each of terminals communicates with a host device through one of subordinate devices of which the terminal is placed in the service area, wherein the host device and the subordinate devices are connected in series through dedicated lines, the host device determines the channel capacities and corresponding counts of time slots for the subordinate devices in accordance with the traffics of the subordinate devices, the counts of time slots are transmitted from the host device to the subordinate devices through prescribed time slots of the dedicated lines, and the subordinate devices communicate with the host device in the time slots determined by the counts of time slots.
In the above cellular communication system, each subordinate device communicates with the host device in the time slots of the determined count starting from the time slot following the last time slot for the preceding subordinate device.
In the above cellular communication system, the host device determines the counts so that the total of the counts does not exceed the counts of time slots in a frame minus the counts of preoccupied time slots.
These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of the preferred mode embodiment thereof, as illustrated in the accompanying drawings.
REFERENCES:
patent: 5551056 (1996-08-01), Koponen et al.
patent: 5715245 (1998-02-01), Suonvieri
patent: 5748624 (1998-05-01), Kondo
Foley & Lardner
NEC Corporation
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