Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Reexamination Certificate
2000-02-07
2004-11-02
Jung, Min (Department: 2739)
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
C370S336000, C370S347000
Reexamination Certificate
active
06813253
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to base station apparatuses, and more particularly to a base station apparatus in a radio communication system, which divides 1 cell into a plurality of sectors and communicates with a plurality of terminal stations according to Time Division Multiple Access (TDMA) via antennas provided for each of the sectors.
Recently, due to increasing number of terminal subscribers in mobile communication systems, there are demands to increase the number of terminal stations that can be accommodated by the base station. In order to efficiently increase the number of terminal stations that can be accommodated by the base station, it is necessary to not only effectively utilize the frequencies, but to also reduce the size and power consumption of the base station facility.
2. Description of the Related Art
FIG. 1
is a diagram showing the construction of a part of a conventional TDMA mobile communication system. The mobile communication system shown in
FIG. 1
includes a mobile switching station
60
which connects to a public network and accommodates a plurality of base station apparatuses BS, a conventional base station apparatus
50
which is one of such base station apparatuses BS, directional antennas a
1
through a
3
which respectively cover communication areas of sectors
1
through
3
, a cell (service area)
100
which is formed by the sectors
1
through
3
, and mobile terminals A through G.
The conventional base station apparatus
50
fixedly allocates frequencies f
1
through f
3
to the sectors
1
through
3
, respectively. In other words, the terminal A in the sector
1
uses the frequency f
1
, the terminals B and C in the sector
2
use the frequency f
2
, and the terminals D through F in the sector
3
use the frequency f
3
, in order to connect to the base station apparatus
50
.
FIG. 2
is a timing chart for explaining a down-communication from the base station apparatus
50
to each of the terminals A through G. It is assumed that transmission slots T
1
through T
3
are used as speech channels for transmitting speech data, and a transmission slot T
4
is used as a control channel for transmitting information related to a connection state of a terminal, connect request and the like. In this example, the terminal A in the sector
1
is accommodated in the time slot T
1
of the frequency f
1
, the terminals B and C in the sector
2
are respectively accommodated in the time slots T
1
and T
2
of the frequency f
2
, and the terminals D through F in the sector
3
are respectively accommodated in the time slots T
1
through T
3
of the frequency f
3
. Hence, in 1 cell of the base station apparatus
50
, a maximum of 3 terminals can be accommodated in each of the sectors
1
through
3
at the respective frequencies f
1
through f
3
, and a total of 9 terminals can be accommodated simultaneously in 1 cell.
However, if an attempt is made in the above case to additionally accommodate a fourth terminal G in the sector
3
, it is impossible to accommodate this terminal G in the sector
3
because there is no vacant time slot of the frequency f
3
in the conventional base station apparatus
50
.
In addition, if the terminal G is forcibly accommodated in the sector
3
, it becomes necessary to increase the frequency used per sector. As a result, it is impossible to efficiently utilize the frequency, and there are problems in that the circuit scale, the power consumption and the cost of the base station apparatus all increase.
SUMMARY OF THE INVENTION
Accordingly, it is a general object of the present invention to provide a novel and useful base station apparatus in which the problems described above are eliminated.
Another and more specific object of the present invention is to provide a base station apparatus which can flexibly and efficiently accommodate a large number of terminals per sector.
Still another object of the present invention is to provide a base station apparatus is used for a radio communication system which divides one cell into a plurality of sectors and communicates with a plurality of terminal stations according to TDMA via antennas which are provided for each of the sectors. The base station apparatus includes a frequency-based distributor and modulator unit which distributes each of channel data to be transmitted in correspondence with each of time slots of a plurality of transmission frequency-based channels, and modulates the distributed channel data to modulated signals, a sector-based distributor and multiplexer unit which distributes the modulated signals to sector-based channels which are prescribed in advance in correspondence with the time slots, and multiplexes the distributed modulated signals for each of the sector-based channels, and a channel connection controller which generates distribution control information of each of the transmission frequency-based channels and the sector-based channels depending on a channel connect or disconnect request. According to the base station apparatus of the present invention, it is possible to flexibly and efficiently accommodate a large number of terminals for each sector, by use of a relatively simple construction. For this reason, it is possible, in a TDMA communication system, to effectively utilize the frequencies, enlarge the number of subscribers that can be accommodated, thereby improving the communication service and the service reliability.
REFERENCES:
patent: 5790959 (1998-08-01), Scherer
patent: 6236866 (2001-05-01), Meyer et al.
patent: 6317423 (2001-11-01), Jantti et al.
patent: 6385188 (2002-05-01), Kim et al.
patent: 6483823 (2002-11-01), Mansour
patent: 62-104232 (1987-05-01), None
patent: 63-272137 (1988-11-01), None
Jung Min
Katten Muchin Zavis & Rosenman
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