Pulse or digital communications – Systems using alternating or pulsating current
Reexamination Certificate
1998-08-04
2002-02-12
Ghayour, Mohammad H. (Department: 2734)
Pulse or digital communications
Systems using alternating or pulsating current
C375S268000, C455S045000, C455S059000, C455S060000
Reexamination Certificate
active
06347120
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a communication method, a transmitter, a receiver, and a cellular radio communication system, and more particularly, is applicable to a portable telephone system.
2. Description of the Related Art
In the field of radio communication, a combination of high priority data and low priority data is generally transmitted. Such a typical digital radio communication system that a combination of high priority data and low priority data is transmitted will be explained below. However, in the explanation described below, one frame of transmission data is composed of the high priority data and the low priority data, and the transmission data for one frame is transmitted by one transmission slot. Note that “frame” means data units when processing digital data, and “slot” means data units when transmitting digital data.
In this radio communication system, as shown in
FIG. 1
, two types of information are transmitted by one frame. Accordingly, one frame is divided into high priority field and low priority field. The high priority data is stored in the high priority field and the low priority data is stored in the low priority field. In this case, not only the information bits of the data to be transmitted, but also error detection and correction bits are stored in each field. Thereby, the receiving side can detect and correct the errors of the received information bits by using the error detection and correction bits.
In addition, the error detection and correction bits having a superior ability to detect and correct errors are generally added to the high priority data, and the error detection and correction bits having a comparatively inferior ability to detect and correct errors are added to the low priority data. For this reason, the error detection and correction bits added to the high priority data tends to be longer in its size.
Here,
FIG. 2
shows the construction of a transmitter for actually transmitting the frame having such structure. As shown in
FIG. 2
, in the transmitter
1
, bit stream DH
1
composed of high priority data is firstly input to a first error correction bit adding circuit
2
, and bit stream DL
1
composed of low priority data is input to a second error correction bit adding circuit
3
.
The first error correction bit adding circuit
2
calculates the error detection and correction bits based on the input bit stream DH
1
and adds this error detection and correction bits to the bit stream DH
1
, so as to form bit stream D
1
which is stored in the high priority field. The bit stream D
1
is output to a frame forming circuit
4
at a later stage. In connection, the first error correction bit adding circuit
2
calculates the error detection and correction bits having a superior ability to detect and correct errors and adds this.
While, the second error correction bit adding circuit
3
calculates the error detection and correction bits based on the input bit stream DL
1
and adds this error detection and correction bits to the bit stream DL
1
, so as to form bit stream D
2
which is stored in the low priority field. The bit stream D
2
is output to a frame forming circuit
4
at a later stage. In connection, the second error correction bit adding circuit
3
calculates the error detection and correction bits having an inferior ability to detect and correct errors and adds this.
The frame forming circuit
4
adds the bit stream D
2
to the end of the bit stream D
1
to form transmission data stream D
3
for one frame, which is output to a modulating circuit
5
. The modulating circuit
5
modulates the transmission data stream D
3
to form transmission symbol stream D
4
, which is output to a transmitting circuit
6
.
The transmitting circuit
6
, after performing the filtering processing on the transmission symbol stream D
4
, performs the digital-to-analog conversion processing on this to generate transmission signal and then performs the frequency conversion processing on the transmission signal to generate transmission signal S
1
. The transmitting circuit
6
transmits the transmission signal S
1
via an antenna
7
, so as to transmit data that the high priority data and the low priority data are combined.
On the other hand, as shown in
FIG. 3
, in a receiver
10
, the transmission signal S
1
transmitted from the transmitter
1
is received at an antenna
11
, which is input to a receiving circuit
12
as reception signal S
2
. The receiving circuit
12
, after performing the filtering processing on the reception signal S
2
, performs the frequency conversion processing on the reception signal S
2
to take out baseband signal, and performs the analog-to-digital conversion processing on the baseband signal to take out reception symbol stream D
5
.
A demodulating circuit
13
performs a predetermined demodulation processing on the reception symbol stream D
5
taken out by the receiving circuit
12
to restore reception data stream D
6
(the reception data stream D
6
is not completely equal to the transmission data stream D
3
, and includes data error received during transmission.), which is output to a field dividing circuit
14
. The field dividing circuit
14
divides the reception data stream D
6
into the bit stream D
7
of the high priority field and the bit stream D
8
of the low priority field, and outputs these bit streams D
7
and D
8
to a first error detection and correction circuit
15
and a second error detection and correction circuit
16
respectively.
The first error detection and correction circuit
15
detects data errors included in the received information bits based on the error detection and correction bits included in the bit stream D
7
, and corrects the data errors, so as to decode the transmitted information bits, which is output as bit stream DH
2
of the high priority data. Similarly, the second error detection and correction circuit
16
detects data errors included in the received information bits based on the error detection and correction bits included in the bit stream D
8
, and corrects the data errors, so as to decode the transmitted information bits, which is output as bit stream DL
2
of the low priority data. By this processing, the receiver
10
respectively decodes the high priority data and the low priority data from the reception signal S
2
.
Transmitting a combination of the high priority data and the low priority data is also performed by the cellular radio communication system such as a portable telephone system actually. This point will be concretely explained below with an example of a portable telephone system.
Generally, in a portable telephone system, the area where communication service is provided is divided into cells each having a desired size, and a base station as a fixed radio station is positioned in each cell. A portable telephone device as a mobile radio station radio-communicates with the base station within the cell where the device exists, and so-called cellular radio communication system is constructed.
In such portable telephone system, to call from a portable telephone device for example, the call processing is performed by the procedure explained below. The portable telephone device firstly transmits control data composed of preamble data and message data to a base station using control channel called random access channel (RACH). The base station constantly monitors the random access channel and detects the existence of the preamble data to detect whether there is a message from the portable telephone device or not. When the preamble data is detected, the base station judges that there is a message from the portable telephone device and detects the message data, and analyzes the contents of the message data.
As a result, if the contents of the message data is a call request, the base station decides the occupational control channel (DCCH) used to communicate with the portable telephone device, and informs this channel number to the portable telephone device using the response control channel (AGCH). After this
Ghayour Mohammad H.
Maioli Jay H.
Sony Corporation
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