Pulse or digital communications – Systems using alternating or pulsating current
Reexamination Certificate
1998-07-01
2002-05-21
Pham, Chi (Department: 2631)
Pulse or digital communications
Systems using alternating or pulsating current
C370S464000
Reexamination Certificate
active
06393064
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of communication for transmitting digital information in time division multiplex frame to perform one-to-multiple digital communication, and in particular, to a method of communication, which is used in mobile wireless communication system such as personal handyphone system (PHS) or in local area network (LAN), in which modulation method can be selected.
The present invention also relates to a data transmission method and a data communication system for data transmission to transmit digital information on time division multiplex frame, and in particular, to a communication system, by which information can be transmitted at high speed when necessary.
2. Description of the Prior Art
As communication system for performing one-to-multiple digital communication, there are mobile wireless communication system such as portable telephone or wire communication system such as LAN. Description is given now on examples of conventional type communication method referring to FIG.
4
and
FIGS. 11
to
13
. As system configuration, there are one master device and a plurality of slave devices. A transmission frame in the direction to transmit from the master device to the slave device is called here a downward transmission frame, and a transmission frame in reverse direction is called an upward transmission frame. The upward and the downward frames use different carrier frequencies.
FIG. 4
shows a configuration of a transmission frame. The transmission frame is in 2.5 ms cycle in both upward and downward transmissions and comprises 4 time slots. Transmission capacity of one time slot is for 50 symbols in the downward frame and 40 symbols in the upward frame. Ten symbols of the upward transmission frame are for guide time to absorb propagation delay. Because QPSK (quadrature phase shift keying) capable to transmit 2 bits per symbol is used as modulation method in this transmission, transmission of 40 kb/s in downward transmission and 32 kb/s in upward transmission can be transmitted for one time slot.
FIG. 11
shows a configuration of a conventional type master device. Reference numeral
701
represents a data processing unit to exchange transmitting and receiving data and to allocate time slots. Reference numeral
702
represents a frame generating unit to assemble the downward frame using base band. Reference numeral
703
represents a QPSK modulator, and
704
a transmission antenna. Numeral
705
represents a receiving antenna, and
706
a QPSK demodulator. Numeral
707
represents a frame disassembling unit, which is in charge of frame synchronizing of the upward frame and divides the data to each time slot and delivers the data to the data processing unit
701
.
FIG. 12
shows a configuration of a conventional type slave device. Reference numeral
801
represents a receiving antenna, and
802
represents a QPSK demodulator. Numeral
803
represents a frame disassembling unit, which is in charge of frame synchronizing of the downward frame and divides the data for each time slot and delivers the data to a data processing unit
804
. The data processing unit
804
picks up only the data of time slot directed to it and outputs it, and further generates information for starting communication and inputs communication data and delivers the data to a time slot generator
805
. The time slot generator
805
outputs a base band signal at time slot timing, at which transmission of the data from the data processing unit
804
is allowed. Reference numeral
806
represents a QPSK modulator, and
807
represents a transmitting antenna.
Next, description will be given on operation of this conventional example.
FIG. 13
shows an outline of the operation. Communication is performed in two phases: a link setup phase and a communication phase. In the link setup phase, each of the master device and one slave device uses a time slot TS
0
exclusively used for link setup and commonly possessed by the slave devices to request starting of communication or exchange information such as time slot numbers used in actual communication. In the subsequent communication phase, communication is performed with the time slot specified in the link setup phase.
FIG. 13
shows an example where TS
2
is specified. In the conventional communication method, communication is preformed in this manner.
FIG. 14
shows a configuration of a conventional type communication system. In
FIG. 14
, the conventional communication system comprises a center device
50
and a plurality of terminal devices
51
to
53
.
FIG. 15
shows a configuration of a conventional type center device. The conventional type center device comprises a data processing unit
601
for exchanging data to be transmitted or received and for inputting or outputting data, control information, etc., a frame generating unit
602
for assembling a downward frame with base band according to the information from the data processing unit
601
, a QPSK modulator
603
, a transmitting antenna
604
, a receiving antenna
605
, a QPSK demodulator
606
, and a frame disassembling unit
607
for performing frame synchronizing of an upward frame, picking up various types of information from the frame and delivering the data to the data processing unit
601
.
FIG. 16
shows a configuration of a conventional type terminal device. The conventional type terminal device comprises a receiving antenna
901
, a QPSK demodulator
902
, a frame disassembling unit
903
for performing frame synchronizing of a downward frame, dividing various types of information in the frame, and delivering the data to the data processing unit
904
, a data processing unit
904
for picking up and outputting only communication information directed to own station, generating an information to start communication, inputting communication data and delivering the data to a frame generating unit
905
, a frame generating unit
905
for assembling an upward frame with base band according to the information from the data processing unit
904
, a QPSK modulator
906
, and a transmitting antenna
907
.
In the following, description will be given on communication from the center device to the terminal devices
51
to
53
, while description on communication in reverse direction is not given here because the same applies to the communication in reverse direction.
FIG. 17
shows a configuration of a data transmission method for transmitting data from the center device
50
to each of the terminal devices
51
to
53
. In
FIG. 17
, the frame comprises a common unit
81
, which contains a frame synchronizing pattern
82
and a control unit
83
and to be received by all terminal devices, and an information unit
84
to be received only by a specific terminal device. This frame is transmitted by &pgr;/4 shift QPSK.
Each of the terminal devices performs symbol synchronizing and frame synchronizing using the synchronizing pattern
82
. Then, after having seen the content of the control unit
83
, it is judged whether the information unit
84
is directed to itself or not. Accordingly, the center device can send information to any of the terminal devices if the terminal device to communicate is specified to the control unit
83
.
However, the first-mentioned conventional communication method as described above is disadvantageous in that communication speed is constant, and it is not possible to provide transmission service at higher speed. To increase communication speed, it is necessary to change to a transmission mode at higher transmission speed, and all of the master device and the slave devices must be renewed. However, this requires much cost and results in waste of money because a slave device usable at lower transmitting speed also must be renewed to a device with higher transmitting speed.
In addition, in the second-mentioned conventional type data transmission method as described above, it is disadvantageous in that the speed of the information unit is constant and high-speed data transmission cannot be carried out
Morita Naoya
Morozumi Masahide
Nagai Tetsuya
Emmanuel Bayard
Gilman & Berner LLP
Hauptman Lowe
Matsushita Electric - Industrial Co., Ltd.
Pham Chi
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