Title of Invention

A COMMUNICATION TERMINCAL APPARATUS, A BASE STATION APPARATUS, AND A RADIO COMMUNICATION METHOD IN A MOBILE COMMUNICATION SYSTEM

Abstract A communication mode determining section (201) determines the communication mode on the basis of the CIR measured by a CIR measuring section (219). The DRC signal generator (202) generates a DRC signal of the number corresponding to the communication mode. A DRC power control section (205) refers to a transmission power table (206) showing the correspondence between the DRC number and the transmission power and increases the transmission power more for a DRC signal having a better line quality of the downstream line on the basis of the transmission power of a pilot signal outputted from a pilot power control section (209).
Full Text DESCRIPTION
communication TERMINAL APPARATUS , BASE STATION APPARATUS ,
AND RADIO communication METHOD
Technical Field
The present invention relates to a communication
terminal apparatus, base station apparatus, and
radio communication method to be used in a cellular
communication system.
Background Art
In a cellular communication system, one base station
performs radio communication with a plurality of
communication terminals simultaneously, and therefore,
as demand has increased in recent years, so has the need
for higher transmission efficiency.
One technology that has been proposed for increasing
the transmission efficiency of a downlink from a base
station to a communication terminal is HDR (High Data
Rate). HDR is a communication method whereby a base
station performs scheduling for allocating communication
resources to communication terminals by time division,
and also sets a transmission rate for each communication
terminal according to the downlink channel quality.
The operations by which a base station and
communication terminals perform radio communication with
HDR are described below. First, the base station
transmits a pilot signal to each communication terminal.
Each communication terminal estimates the downlink
channel quality using a CIR (desired carrier to
interference ratio) based on the pilot signal, etc. , and
finds a transmission rate at which communication is
possible. Then, based on the transmission rate at which
communication is possible, each communication terminal
selects a communication mode, which is a combination of
packet length, coding method, and modulation method, and
transmits a data rate control (hereinafter referred to
as "DRC") signal indicating the communication mode to
the base station.
The type of modulation method that can be used in
each system is predetermined as BPSK, QPSK, 16QAM, 64QAM,
and so forth. Also, the type of coding that can be used
in each system is predetermined as 1/2 turbo code, 1/3
turbo code, 3/4 turbo code, and so forth. Further, a
plurality of transmission rates that can be used in each
system are predetermined according to a combination of
packet length, modulation method, and coding method.
Each communication terminal selects a combination whereby
communication can be performed most efficiently with the
current downlink channel quality, and transmits a DRC
signal indicating the selected communication mode to the
base station. Generally, DRC signals are represented by
numbers from 1 to N, with a higher number indicating a
proportionally better downlink channel quality.
Based on the DRC signal transmitted from each
communication terminal, the base station sets a
transmission rate for each communication terminal, and
sends a signal to each communication terminal via a control
channel indicating communication resource allocation to
each communication terminal. Generally, taking
improvement of system transmission efficiency into
consideration, communication resources are allocated
with priority to the communication terminal that has the
best downlink channel quality—that is to say, the
communication terminal that transmits the
highest-numbered DRC signal.
The base station then transmits data only to the
relevant communication terminal in its allocated time.
For example, if time t1 has been allocated to communication
terminal A, in time tl the base station transmits data
only to communication terminal A, and does not transmit
data to a communication terminal other than communication
terminal A.
In this way, data transmission efficiency has
conventionally been increased for the overall system by
setting a transmission rate for each communication
terminal according to channel quality by means of HDR,
and performing communication resource allocation with
priority to a communication terminal with a high
transmission rate at which communication is possible.
However, if the communication mode determined by
a communication terminal is received erroneously by the
base station due to deterioration of the channel
conditions on the uplink from the communication terminal
to the base station, or the like, the base station will
transmit data using that erroneous mode. As the
determined communication mode and the communication mode
of data transmitted to the communication terminal are
different, the communication terminal cannot demodulate
or decode the data.
Also, when a base station such as that described
above has allocated time tl to communication terminal
A, in time tl the base station transmits data only to
communication terminal A, and does not transmit data to
a communication terminal other than communication
terminal A.
Due to the above, a problem arises in that_, if the
communication mode determined by a communication terminal
is received erroneously by the base station, there will
be an interval during which time-divided communication
resources are not used, and downlink throughput falls.
Disclosure of Invention
It is an object of the present invention to provide
a communication terminal apparatus, base station
apparatus, and radio communication method that make it
possible to prevent a fall in downlink throughput in a
communication system in which communication resources
are allocated to communication terminals based on
downlink channel quality.
In order to achieve the above-described object, in
the present invention, with respect to information, among
information indicative of downlink channel quality, which
has a possibility of decreasing the downlink throughput
when the information is received erroneously in a base
station, a communication terminal provides such
information with less susceptibility to errors in the
propagation path to transmit. It is thereby possible to
prevent the downlink throughput from decreasing.
Brief Description of Drawings
FIG.l is a graph illustrating DRC signal selection
frequency in a base station;
FIG.2 is a block diagram showing a configuration
of a base station according to Embodiment 1 of the present
invention;
FIG.3 is a block diagram showing the configuration
of a communication terminal according to Embodiment 1
of the present invention;
FIG.4 is a drawing showing the contents of the
transmission power table provided in a communication
terminal according to Embodiment 1 of the present
invention;
FIG.5 is a block diagram showing another
configuration of a base station according to Embodiment
1 of the present invention;
FIG.6 is a block diagram showing the configuration
of a communication terminal according to Embodiment 2
of the present invention;
FIG. 7 is a drawing showing the contents of the code
word table provided in a communication terminal according
to Embodiment 2 of the present invention;
PIG.8 is a block diagram showing the configuration
of a base station according to Embodiment 3 of the present
invention;
FIG. 9 is a block diagram showing the configuration
of a communication terminal according to Embodiment 3
of the present invention;
FIG.10 is a block diagram showing a configuration
of a base station according to Embodiment 4 of the present
invention;
FIG. 11 is a block diagram showing the configuration
of a communication terminal according to Embodiment 4
of the present invention;
FIG.12 is a block diagram showing another
configuration of a base station according to Embodiment
4 of the present invention;
FIG. 13 is a block diagram showing the configuration
of a communication terminal according to Embodiment 5
of the present invention;
FIG. 14 is a block diagram showing the configuration
of a communication terminal according to Embodiment 6
of the present invention;
FIG. 15 is a block diagram showing the configuration
of the CIR signal creation section of a communication
terminal according to Embodiment 6 of the present
invention;
FIG. 16 is a block diagram showing the configuration
of the CIR signal creation section of a communication
terminal according to Embodiment 7 of the present
invention; and
FIG. 17 is a block diagram showing the configuration
of the CIR signal creation section of a communication
terminal according to Embodiment 8 of the present
invention.
Best Mode for Carrying out the Invention
With reference now to the accompanying drawings,
embodiments of the present invention will be explained
in detail below.
(Embodiment 1)
As stated above, a base station allocates
communication resources with priority to the
communication terminal with the best downlink channel
quality. In other words, a base station selects the
highest-numbered DRC signal, and allocates communication
resources with priority to the communication terminal
that transmitted that selected DRC signal. Thus, DRC
signal selection frequency is as shown in FIG.1. FIG.1
is a graph illustrating DRC signal selection frequency
in a base station. In this figure, numbers 1 to 5 are
used as DRC numbers, with a higher number representing
a proportionally better channel quality.
As shown in FIG.1, the higher the number of a DRC
signal, the greater is the frequency of its selection
by the base station. That is to say, the better the
downlink channel quality of a communication terminal,
the higher is the frequency with which communication
resources are allocated to that communication terminal.
This kind of relationship arises from the fact that there,
are many communication terminals, and there is an
increased probability of there being a communication
terminal with good downlink channel quality.
Thus, the selection frequency of each DRC signal
differs according to channel quality. That is to say,
since a DRC signal indicating that downlink channel
quality is good tends to be selected with greater frequency,
there is a high probability that downlink throughput will
fall if a DRC signal indicating that downlink channel
quality is good is received erroneously. Also, since a
DRC signal indicating that downlink channel quality is
poor tends to be selected with lower frequency, there
is little effect of producing a fall in downlink throughput
if a DRC signal indicating that downlink channel quality
is poor is received erroneously.
Thus, a communication terminal according to
Embodiment 1 of the present invention transmits at
proportionally higher transmission power a DRC signal
indicating that downlink channel quality is good. Also,
a base station according to Embodiment 1 of the present
invention excludes DRC signals with reception power lower
than a predetermined threshold value in performing
communication resource allocation.
FIG.2 is a block diagram showing a configuration
of a base station according to Embodiment 1 of the present
invention.
In FIG.2, an allocation section 101 determines
communication resource allocation to each communication
terminal based on DRC signals excluding DRC signals
detected by unused DRC detection sections 116 described
later herein from among DRC signals extracted by
demodulators 114 described later herein. Then, based on
the determined communication resource allocation, the
allocation section 101 notifies a buffer 102 for output
of downlink transmit data, indicates the downlink
transmit data coding method to an adaptive coding section
103, and indicates the downlink transmit data modulation
method to an adaptive modulator 104.
The buffer 102 holds downlink transmit data, and
outputs downlink transmit data for a predetermined
communication terminal to the adaptive coding section
103 in accordance with the directions of the allocation
section 101. The adaptive coding section 103 codes the
output signal from the buffer 102 in accordance with the
directions of the allocation section 101, and outputs
the resulting signal to the adaptive modulator 104. The
adaptive modulator 104 modulates the output signal from
the adaptive coding section 103 in accordance with the
directions of the allocation section 101, and outputs
the resulting signal to a spreading section 105.
Spreading section 105 spreads the output signal from the
adaptive modulator 104, and outputs the resulting signal
to a multiplexer 108.
A modulator 106 modulates a pilot signal and outputs
it to a spreading section 107. Spreading section 107
spreads the output signal from the modulator 106, and
outputs the resulting signal to the multiplexer 108.
The multiplexer 108 performs time multiplexing of"
the spread pilot signal with the spread downlink transmit
data at predetermined intervals, and outputs the
resulting signal to a transmit RP section 109. The
transmit RF section 109 converts the frequency of the
output signal from the multiplexer 108 to radio frequency,
and outputs the resulting signal to a duplexer 110.
The duplexer 110 transmits the output signal from
the transmit RF section 109 as a radio signal from an
antenna 111 to a communication terminal. Moreover, the
duplexer 110 outputs the signals transmitted from each
communication terminal and received by antenna 111 to
receive RF section 112.
A receive RF section 112 converts the frequency of
a radio frequency signal output from the duplexer 110
to baseband, and outputs the resulting signal to a
despreading section 113. The despreading section 113
despreads the baseband signal using the spreading code
used to spread the DRC signal, and outputs the resulting
signal to the demodulator 114 and a reception power
calculation section 115.
The demodulator 114 demodulates the output signal
from the despreading section 113 and extracts the DRC
signal, and outputs this signal to the allocation section
101.
The reception power calculation section 115
measures the reception power of the despread DRC signal,
which is output to the unused DRC detection section 116.
In the unused DRC detection section 116 is set a
predetermined threshold value, as described later herein,
and a DRC signal of reception power lower than this
threshold value is detected, and the result of the
detection is output to the allocation section 101.
A despreading section 113, demodulator 114,
reception power calculation section 115, and unused DRC
detection section 116 are provided for each communication
terminal. From each demodulator 114 a DRC signal for the
corresponding communication terminal is output, and from
each unused DRC detection section 116 a detection result
for the corresponding communication terminal is output.
FIG.3 is a block diagram showing the configuration
of a communication terminal according to Embodiment 1
of the present invention . In FIG. 3 , a communication mode
determination section 201 determines a communication mode
indicating a combination of modulation method and coding
method based on a CIRmeasured by a CIR measurement section
219 described later herein, and outputs the result to
a DRC signal creation section 2 02 . The communication mode
determination section 201 also indicates the downlink
receive data demodulation method to an adaptive
demodulator 216, and indicates the downlink receive data
decoding method to an adaptive decoding section 217, based
on the determined communication mode.
The DRC signal creation section 202 creates a DRC
signal with a number corresponding to the communication
mode output from the communication mode determination
section 201, and outputs this DRC signal to a modulator
203 and DRC power controller 205.
Modulator 203 modulates the DRC signal and outputs
the resulting signal to a spreading section 204.
spreading section 204 spreads the output signal from
modulator 203 and outputs the resulting signal to the
DRC power controller 205. The DRC power controller 205
refers to a transmission power table 206 that shows the
correspondence between DRC numbers and transmission power,
controls the DRC signal transmission power based on the
transmission power of a pilot signal output from a pilot
power controller 209 described later herein, and outputs
the DRC signal that has undergone transmission power
control to a multiplexer 210. The actual method of
controlling DRC signal transmission power will be
described later herein.
A modulator 207 modulates the pilot signal and
outputs the resulting signal to a spreading section 208.
Spreading section 208 spreads the output signal from
modulator 207 and outputs the resulting signal to the
pilot power controller 209. The pilot power controller
209 controls the transmission power of the pilot signal,
and outputs the pilot signal that has undergone
transmission power control to the multiplexer 210. The
pilot power controller 209 also outputs the pilot signal
transmission power to the DRC power controller 205.
The multiplexer 210 performs time multiplexing of
the DRC signal that has undergone transmission power
control and the pilot signal that has undergone
transmission power control at predetermined intervals,
and outputs the resulting signal to a transmit RF section
211. The transmit RF section 211 converts the frequency
of the output signal from the multiplexer 210 to radio
frequency, and outputs the resulting signal to a duplexer
212.
The duplexer 212 transmits the output signal from
the transmit RF section 211 as a radio signal from an
antenna 213 to the base station. Also, a signal
transmitted as a radio signal by the base station and
received as a radio signal by the antenna 213 is output
by the duplexer 212 to a receive RF section 214.
The receive RF section 214 converts the frequency
of the radio frequency signal output from the duplexer
212 to baseband, and outputs the resulting signal to a
despreading section 215 and a despreading section 218.
Despreading section 215 despreads the data
component of the baseband signal and outputs the resulting
signal to the adaptive demodulator 216. The adaptive
demodulator 216 demodulates the output signal from
despreading section 215 in accordance with the directions
of the communication mode determination section 201, and
outputs the resulting signal to the adaptive decoding
section 217. The adaptive decoding section 217 decodes
the output signal from the adaptive demodulator 216 in
accordance with the directions of the communication mode
determination section 201, and obtains receive data.
Despreading section 218 despreads the pilot signal
component of the baseband signal and outputs the resulting
signal to a CIR measurement section 219. The CIR
measurement section 219 measures the CIR of the pilot
signal output from despreading section 218, and outputs
the result to the communication mode determination
section 201.
Next, the procedure for transmission/reception of
signals between the base station shown in FIG.2 and the
communication terminal shown in FIG.3 will be described.
First, at the start of communication, a pilot signal
is modulated by the modulator 106 in the base station,
is spread by spreading section 107, and is output to the
multiplexer 108. Only the spread pilot signal is output
from the multiplexer 108 to the transmit RF section 109.
The spread pilot signal is frequency-converted to radio
frequency by the transmit RF section 109, and transmitted
to communication terminals as a radio signal from the
antenna 111 via the duplexer 110.
A radio signal of only the pilot signal component
transmitted as a radio signal from the base station is
received by theantenna 213 of the communication terminal,
passes through the duplexer 212, and is
frequency-converted to baseband by the receive RF section
214. The pilot signal component of the baseband signal
is despread by despreading section 218, and output to
the CIR measurement section 219.
Next, in the CIR measurement section 219, the CIR
of the pilot signal output from despreading section 218
is measured, and based on the CIR, the communication mode
is determined by the communication mode determination
section 201. Then a DRC signal with a number
corresponding to the communication mode is created by
the DRC signal creation section 202.
The DRC signal is modulated by modulator 203 , spread
by spreading section 204, and output to the DRC power
controller 205. In the DRC power controller 205, the DRC
signal transmission power is controlled based on the
transmission power of the pilot signal output from the
pilot power controller 209, and the ratios of pilot signal
transmission power to DRC signal transmission power set
beforehand in the transmission power table 206.
The contents set in the transmission power table
206 will be described below. FIG.4 is a drawing showing
the contents of the transmission power table provided
in a communication terminal according to Embodiment 1
of the present invention.
The transmission power table 206 shows the
correspondence between DRC numbers and DRC signal
transmission power, set so that the higher the DRC number,
the higher is the transmission power. Here, numbers 1
to 5 are used as DRC numbers, with a higher number
representing a proportionally better downlink channel
quality- That is to say, in the settings in the
transmission power table 206, the better the downlink
channel quality indicated by a DRC signal, the higher
is the transmission power.
As explained above, the frequency of selection by
the base station tends to be proportional to the downlink
channel quality indicated by a DRC signal, and therefore
in this embodiment, transmission power is higher, and
susceptibility to errors lower, the better the downlink
channel quality indicated by a DRC signal. As a result,
the probability of a DRC signal that indicates that
downlink channel quality is good being received
erroneously can be made lower than the probability of
a DRC signal that indicates that downlink channel quality
is poor being received erroneously. In other words, the
probability of a DRC signal with a high frequency of
selection by the base station being received erroneously
can be made lower than the probability of a DRC signal
with a low frequency of selection by the base station
being received erroneously.
The DRC signal transmission power values set in the
transmission power table 206 are expressed as a ratio
to the pilot signal transmission power. Here, as shown
in FIG.4, the settings are arranged so that DRC number
3 in themiddle of DRC numbers 1 to 5 is taken as a reference,
and DRC signals indicating a lower number than DRC number
3 are transmitted at lower transmission power than the
pilot signal transmission power, while DRC signals
indicating a higher number than DRC number 3 are
transmitted at higher transmission power than the pilot
signal transmission power. That is to say, the settings
are arranged so that DRC signals indicating a poorer
channel quality than a predetermined channel quality
(here, the channel quality corresponding to a DRC signal
with DRC number 3) are transmitted at lower transmission
power than the pilot signal transmission power, while
DRC signals indicating a better channel quality than the
predetermined channel quality are transmitted at higher
transmission power than the pilot signal transmission
power.
Thus, with this embodiment, by setting DRC signals
for which transmission power is increased and DRC signals
for which transmission power is decreased in comparison
with conventional DRC signal transmission power (here,
that is, pilot signal transmission power), and making
the total of DRC signal transmission power increases and
decreases ±0 dB, it is possible to make DRC signals
indicating that downlink channel quality is good
proportionally less susceptible to errors while keeping
average DRC signal transmission power constant compared
with a conventional system. That is to say, it is possible
to proportionally reduce susceptibility to errors of DRC
signals indicating that downlink channel quality is good
without reducing uplink capacity compared with a
conventional system.
Also, since, in this way, DRC signals indicating
that downlink channel quality is poor (DRC signals with
DRC numbers 1 and 2 in FIG.4) are transmitted at lower
transmission power than in a conventional system, it is
possible to reduce power consumption in a communication
terminal that is located far from the base station and
for which there is a high probability of transmitting
a DRC signal indicating that downlink channel quality
is poor. That is to say, in the case of a communication
terminal that transmits a DRC signal indicating that
downlink channel quality is poor, whereas the DRC signal
was previously transmitted at transmission power that
was high to begin with, according to this embodiment the
DRC signal transmission power can be made lower than that
high transmission power, enabling communication terminal
power consumption to be greatly reduced.
As the frequency of selection by a base station is
low to begin with for a DRC signal indicating that downlink
channel quality is poor, there is almost no effect of
producing a fall in throughput due to transmitting a DRC
signal indicating that downlink channel quality is poor
at lower transmission power than previously in this way.
Also, with this embodiment, DRC signals indicating
that uplink channel quality is good (DRC signals with
DRC numbers 4 and 5 in FIG. 4) are transmitted at higher
transmission power than in a conventional system.
However, there is a high possibility of a DRC signal
indicating that uplink channel quality is good being
transmitted from a communication terminal located
comparatively near the base station. Also, due to pilot
signal transmission power control that is performed
constantly on an uplink, the transmission power of a pilot
signal transmitted from a communication terminal located
comparatively near the base station (that is, the
conventional DRC signal transmission power) is low to
begin with. Therefore, in the case of a communication
terminal that transmits a DRC signal indicating that
uplink channel quality is good, DRC signal transmission
power remains low and power consumption remains low even
though the previously originally low DRC signal
transmission power increases, and so there is almost no
effect on power consumption.
In the DRC power controller 205, the DRC signal
transmission power is obtained by having the transmission
power of the pilot signal output from the pilot power
controller 209 adjusted in accordance with the ratios
set in the transmission power table 206. Then, in the
DRC power controller 205, the transmission power of the
DRC signal output from spreading section 204 is adjusted
to this obtained transmission power, and a DRC signal
that has been subjected to transmission power control
is output to the multiplexer 210. To give a specific
example, if the number of the DRC signal output from the
DRC signal creation section 202 to the DRC power controller
205 is 5, the transmission power of the DRC signal output
from spreading section 204 is adjusted to a transmission
power 2 dB lower than the transmission power of the pilot
signal output from the pilot power controller 209.
The DRC signal that has undergone transmission power
control is multiplexed with the pilot signal by the
multiplexer 210, frequency-converted to radio frequency
by the transmit RF section 211, and transmitted to the
base station as a radio signal from the antenna 213 via
the duplexer 212.
The radio signal transmitted from the communication
terminal is received by the antenna 111 of the basestation,
and input to the receive RF section 112 via the duplexer
110. The signal input to the receive RF section 112 is
frequency-converted to baseband, despread by the
despreading section 113 using the spreading code used
to spread the DRC signal, and output to the demodulator
114 and reception power calculation section 115.
In the demodulator 114 the output signal from the
despreading section 113 is demodulated, andtheDRC signal
is extracted and output to the allocation section 101.
Here, since a DRC signal indicating that downlink
channel quality is poor is transmitted by a communication
terminal at lower transmission power than in a
conventional system, the probability of a DRC signal
indicating that downlink channel quality is poor being
received erroneously by the base station is increased.
Also, as stated above, if communication resource
allocation is performed based on an erroneously received
DRC signal, downlink throughput will fall.
Thus, in the reception power calculation section
115, the reception power of the despread DRC signal is
measured, and is output to the unused DRC detection section
116. The lowest reception power at which an error does
not occur in a DRC signal indicating that downlink channel
quality is poorest (a DRC signal with DRC number 1 in
FIG. 4 ) has been set beforehand in the unused DRC detection
section 116 as a threshold value. Then, in the unused
DRC detection section 116, a DRC signal of reception power
lower than this threshold value is detected, and the
detection result is output to the allocation section 101.
A DRC signal detected by the unused DRC detection section
116 is a DRC signal that is not used by the allocation
section 101 in determining communication resource
allocation.
In the allocation section 101, communication
resource allocation to each communication terminal is
determined based on the DRC signals remaining after DRC
signals detected by the unused DRC detection section 116
have been excluded from the DRC signals extracted by the
demodulator 114.
Thus , in a base station according to this embodiment,
a DRC signal of reception power lower than the lowest
reception power at which a DRC signal indicating that
downlink channel quality is poorest is not received
erroneously is excluded. That is to say, in a base station
according to this embodiment, a notification signal
susceptible to errors is excluded in determining downlink
communication resource allocation. Therefore,
according to a base station of this embodiment, even though
a DRC signal indicating that downlink channel quality
is poor is transmitted at lower transmission power than
in a conventional system, it is possible to prevent
communication resource allocation from being determined
based on an erroneous DRC signal.
Thus, according to this embodiment, the better the
downlink channel quality indicated by a DRC signal, the
higher is the transmission power at which transmission
is performed, and therefore it is possible to make DRC
signals indicating that downlink channel quality is good
proportionally less susceptible to errors, and to reduce
the error occurrence rate of DRC signals for which the
probability of selection by a base station is high. By
this means it is possible to reduce the possibility of
communication resource allocation being determined based
on an erroneous DRC signal, and so to prevent a fall in
downlink throughput.
A base station according to this embodiment may also
be configured as shown in FIG.5. FIG.5 is a block diagram
showing another configuration of a base station according
to Embodiment 1 of the present invention. That is to say,
a base station may be configured in such a way that the
reception power calculation section 115 and unused DRC
detection section 116 shown in FIG.2 are replaced by a
likelihood calculation section 301 and unused DRC
detection section 302. In the following description,
parts identical to those in FIG. 2 are assigned the same
reference numerals as in FIG.2 and their detailed
explanations are omitted.
In FIG.5, the likelihood calculation section 301
calculates a likelihood that indicates the probable
degree of certainty of a DRC signal, and outputs the
calculation result to the unused DRC detection section
302. The lowest likelihood at which an error does not
occur in a DRC signal indicating that downlink channel
quality is poorest has been set beforehand in the unused
DRC detection section 302 as a threshold value. Then,
in the unused DRC detection section 302, a DRC signal
with a likelihood lower than this threshold value is
detected, and the detection result is output to the
allocation section 101.
In this way the same kind of effect as described
above is also obtained when a base station according to
this embodiment is configured as shown in FIG.5.
(Embodiment 2)
In a communication terminal according to Embodiment
2 of the present invention, the better the downlink channel
quality indicated by a DRC signal, the larger is the code
word minimum distance of the code word to which that DRC
signal is converted with respect to other DRC signal code
words before being transmitted.
FIG.6 is a block diagram showing the configuration
of a communication terminal according to Embodiment 2
of the present invention. As shown in this figure, a
communication terminal according to this embodiment is
configured in such a way that the modulator 203 , spreading
section 204, DRC power controller 205, and transmission
power table 206 shown in FIG.3 are replaced by a code
word selector 401, code word table 402, modulator 403,
and spreading section 404 . In the following description,
parts identical to those in FIG.3 are assigned the same
reference numerals as in FIG.3 and their detailed
explanations are omitted.
The code word selector 401 refers to the code word
table 402, converts a DRC signal created by the DRC signal
creation section 202 to a predetermined code word, and
outputs the code word to modulator 403. Modulator 403
modulates the code word and outputs it to spreading section
404. Spreading section 404 spreads the output signal from
modulator 403 and outputs the resulting signal to a
multiplexer 210.
Next, the operation of a communication terminal
according to this embodiment will be described.
First, the contents set in the code word table 402
will be described. FIG.7 is a drawing showing the
contents of the code word table provided in a communication
terminal according to Embodiment 2 of the present
invention.
The code word table 402 shows the correspondence
between DRC numbers and code words after DRC signal
conversion, set so that the higher the DRC number, the
larger is the code word minimum distance of the code word
to which the DRC signal is converted. Here, numbers 1
to 5 are used as DRC numbers, with a higher number
representing a proportionally better downlink channel
quality. That is to say, in the settings in the code word
table 402, the better the downlink channel quality
indicated by a DRC signal, the larger is the code word
minimum distance of the code word to which the DRC signal
is converted.
Here, "code word distance" is the number of bits
that differ between code words, and "code word minimum
distance" is the minimum number of bits by which a
particular code word differs with respect to all other
code words. To be specific, the code word for a DRC signal
with DRC number 5 is "111111111", and this code word
"111111111" differs by a minimum of 6 bits when compared
with any of the code words corresponding to DRC signals
with DRC numbers 1 to 4 . Therefore, the code word minimum
distance of the code word for a DRC signal with DRC number
5 is 6. Similarly, the code word minimum distance of the
code word for a DRC signal with DRC number 4 is 3.
Thus, the code word for a DRC signal with DRC number
5 is less likely to be mistaken for another code word
than the code word for a DRC signal with DRC number 4.
That is to say, the larger code word minimum distance
of a code word, the less likely it is to be mistaken for
another code word.
In the code word selector 401, a DRC signal output
from the DRC signal creation section 202 is converted
to a code word set in the code word table 402, and output
to modulator 403. To give a specific example, if the DRC
signal output from the DRC signal creation section 202
is a number 5 DRC signal, it is converted to code word
"111111111".
Following conversion, the code word is modulated
by modulator 403 and spread by spreading section 404.
The spread code word is multiplexed with a pilot signal
by a multiplexer 210, frequency-converted to radio
frequency by a transmit RF section 211, and transmitted
to the base station as a radio signal from an antenna
213 via a duplexer 212.
Thus, according to this embodiment, the better the
downlink channel quality indicated by a DRC signal, the
larger is the code word minimum distance of the code word
to which that DRC signal is converted with respect to
other DRC signal code words before being transmitted,
and therefore it is possible to make DRC signals indicating
that downlink channel quality is good proportionally less
susceptible to errors, and to reduce the error occurrence
rate of DRC signals for which the probability of selection
by a base station is high. By this means it is possible
to reduce the possibility of communication resource
allocation being determined based on an erroneous DRC
signal, and so to prevent a fall in downlink throughput.
Also, according to this embodiment, it is possible
to reduce the error occurrence rate of DRC signals for
which the probability of selection by a base station is
high without increasing DRC signal transmission power,
thereby making it possible to reduce the possibility of
communication resource allocation being determined based
on an erroneous DRC signal without increasing
communication terminal power consumption.
Moreover, according to this embodiment, it is
possible to change the degree of insusceptibility to
errors of code words corresponding to DRC signals while
keeping the code length of code words constant, and
therefore it is not necessary to provide a plurality of
demodulation systems in accordance with different code
lengths in a base station, thus enabling the apparatus
configuration of a base station to be simplified.
(Embodiment 3)
A base station according to Embodiment 3 of the
present invention transmits to a communication terminal
a control signal for table rewriting based on the rate
of occurrence of DRC signals that are excluded when
communication resource allocation is determined, and a
communication terminal according to Embodiment 3 of the
present invention rewrites the contents of a transmission
power table or code word table based on a control signal
transmitted from the base station.
FIG. 8 is a block diagram showing the configuration
of a base station according to Embodiment 3 of the present
invention. As shown in this figure, a base station
according to this embodiment is configured by further
providing the configuration shown in FIG.2 with a
detection rate calculation section 501, control signal
creation section 502, modulator 503, and spreading
section 504. in the following description, parts
identical to those in FlG.2areassignedthe same reference
numerals as in FIG.2 and their detailed explanations are
omitted.
In FIG.8, the detection rate calculation section
501 calculates the rate of detection by the unused DRC
detection section 116 and outputs the result to the control
signal creation section 502. That is to say, the
detection rate calculation section 501 calculates the
rate of occurrence of DRC signals that are excluded when
communication resource allocation is determined. Based
on the detection rate, the control signal creation section
502 creates a control signal for table rewriting
(hereinafter referred to as "table rewrite signal"),
which is output to modulator 5 03 . Modulator 5 03 modulates
the table rewrite signal and outputs it to spreading
section 504. Spreading section 504 spreads the output
signal from modulator 503 and outputs the resulting signal
to the multiplexer 108.
FIG. 9 is a block diagram showing the configuration
of a communication terminal according to Embodiment 3
of the present invention. As shown in this figure, a
communication terminal according to this embodiment is
configured by further providing the configuration shown
in FIG. 3 with a despreading section 601, demodulator 602,
and table rewriting section 603. In the following
description, parts identical to those in FIG.3 are
assigned the same reference numerals as in FIG. 3 and their
detailed explanations are omitted.
In FIG.9, despreading section 601 despreads a
baseband signal using the spreading code used to spread
the table rewrite signal, and outputs the resulting signal
to the demodulator 602 . The demodulator 602 demodulates
the output signal from despreading section 601 and
extracts the table rewrite signal, which is output to
the table rewriting section 603. The table rewriting
section 603 rewrites the contents of the transmission
power table in accordance with the table rewrite signal.
Next, the procedure for transmission/reception of
signals between the base station shown in FIG.8 and the
communication terminal shown in FIG. 9 will be described.
First, in the detection rate calculation section
501 of the base station, the detection rate of the unused
DRC detection section 116 is calculated and is output
to the control signal creation sect ion 502. The detection
rate can be calculated, for example, from the number of
detections in a predetermined time.
A predetermined threshold value for the detection
rate has been set in the control signal creation section
502, and this threshold value is compared with the
detection rate calculated by the detection rate
calculation section 501. If the detection rate
calculated by the detection rate calculation section 501
is greater than or equal to the threshold value, a table
rewrite signal ordering all transmission power values
set in the transmission power table 206 to be increased
is created, and is output to modulator 503. That is to
say, if the rate of occurrence of DRC signals that are
excluded when communication resource allocation is
determined is greater than or equal to the predetermined
threshold value, the control signal creation section 502
creates a table rewrite signal that orders all DRC signal
transmission power values to be increased simultaneously
from their current values.
The table rewrite signal is modulated by modulator
503, spread by spreading section 504, and output to the
multiplexer 108. The spread table rewrite signal is
multiplexed with transmit data and the pilot signal in
the multiplexer 108, frequency-converted to radio
frequency by the transmit RF section 109, and transmitted
to communication terminals as a radio signal from the
antenna 111 via the duplexer 110.
The radio signal transmitted from the base station
is received by the antenna 213 of the communication
terminal, passes through the duplexer 212, and is
frequency-converted to baseband by the receive RF section
214. The baseband signal is despread by despreading
section 601 and demodulated by the demodulator 602, and
the table rewrite signal is extracted. The extracted
table rewrite signal is output to the table rewriting
section 603.
The contents of the transmission power table 206
are then rewritten by the table rewriting section 603
in accordance with the table rewrite signal. That is to
say, the table rewriting section 603 increases all the
transmission power values set in the transmission power
table 206.
In the above description, the configuration is such
that the table rewriting section 603 rewrites the contents
of the transmission power table 206, but this embodiment
may also be applied to a communication terminal according
to Embodiment 2, and a configuration may be used whereby
the table rewriting section 603 rewrites the contents
of the code word table 402 shown in FIG.6.
In this case, if the detection rate calculated by
the detection rate calculation section 501 is greater
than or equal to the threshold value, the control signal
creation section 502 of a base station according to this
embodiment creates a table rewrite signal ordering all
code word minimum distances set in the code word table
402 to be increased. That is to say, if the rate of
occurrence of DRC signals that are excluded when
communication resource allocation is determined is
greater than or equal to the predetermined threshold value,
the control signal creation section 502 creates a table
rewrite signal that orders all code word minimum distances
of code words corresponding to DRC signals to be increased
simultaneously from their current values . Then the table
rewriting section 603 rewrites the contents of the code
word table 4 02 in accordance with the table rewrite signal.
That is to say, the table rewriting section 603 rewrites
the code words set in the code word table 402 with code
words all of whose code word minimum distances are larger
than at present.
Thus, according to this embodiment, the contents
of the transmission power table or code word table are
rewritten based on the rate of occurrence of DRC signals
that are excluded when communication resource allocation
is determined. In other words, in this embodiment,
transmission power table or code word table contents are
rewritten adaptively in accordance with variations in
the communication environment. That is to say, according
to this embodiment, when the communication environment
deteriorates and the rate of occurrence of DRC signals
that are excluded when communication resource allocation
is determined reaches or exceeds a predetermined
threshold value, the transmission power of each DRC signal
is increased, or the code word minimum distance of the
code word corresponding to each DRC signal is increased,
thereby enabling the DRC signal error occurrence rate
to be held down even when the communication environment
deteriorates.
In this embodiment, the predetermined detection
rate threshold value is decided upon considering
appropriately the environment in which the
communication system is used.
Moreover, with this embodiment, it is also possible
to further set a second predetermined threshold value
in the control signal creation section 502 to create a
table rewrite signal ordering all transmission power
values set in the transmission power table 206 to be
decreased when the detection rate calculated by the
detection rate calculation section 501 falls below this
second threshold value. By this means, it is possible
to reduce DRC signal transmission power when DRC signal
reception quality becomes excessive, thereby enabling
communication terminal power consumption to be decreased .
Furthermore, in this embodiment, table rewriting
is performed based on the rate of detection by the unused
DRC detection section 116, but it is also possible to
rewrite a table based on the distribution of DRC signals
used in determining communication resource allocation
from among DRC signals transmitted from mobile stations,
so that that distribution is optimized. In this case,
the base station shown in FIG.8 is configured with the
detection rate calculation section replaced by a used
DRC distribution determination section, which determines
the distribution of DRC signals used in communication
resource allocation determination based on DRC signals
output from the demodulator 114 and detection results
output from the unused DRC detection section 116, and
outputs a signal indicating that distribution to the
control signal creation section 502 . The control signal
creation section 502 then creates a table rewrite signal
based on the signal indicating the distribution output
from the used DRC distribution determination section.
(Embodiment 4)
A communication terminal according to Embodiment
4 of the present invention transmits at higher
transmission power in proportion to CIR information that
indicates that downlink channel quality is good. A base
station according to Embodiment 4 of the present invention
excludes CIR information for which the reception power
is lower than a predetermined threshold value in
performing communication resource allocation.
In above-described Embodiment 1, a communication
terminal determines the communication mode based on the
CIR and transmits a DRC signal corresponding to that
determined communication mode to the base station at
predetermined transmission power, and the base station
determines communication resource allocation to each
communication terminal based on the DRC signals. DRC
signal can be represented with far fewer bits than other
information indicating downlink, channel quality (such
as a downlink CIR, for example), and therefore use of
a DRC signal has the advantage of enabling the downlink
channel utilization efficiency to be increased. On the
other hand, since a communication terminal must be
provided with a table for communication mode
determination, a table for DRC signal creation, and so
forth to determine the communication mode and create a
DRC signal, there are the disadvantages of increased
communication terminal power consumption and apparatus
size.
Thus, in this embodiment, a communication terminal
transmits CIR information to the base station at
predetermined transmission power, and the base station
determines the communication mode based on the CIR
information and then determines communication resource
allocation to each communication terminal. As a result,
although there is the disadvantage of a slight decrease
in the uplink channel utilization efficiency, the fact
that communication terminals do not have to determine
the communication mode and create a DRC signal, and do
not need to be provided with a communication mode
determination table, DRC signal creation table, and so
forth, offers the major advantage of enabling
communication terminal power consumption and apparatus
size to be reduced. Also, in this embodiment, it is
possible for CIR information for a plurality of terminals
to be compared in the base station, and the correct
communication mode to be determined with certainty,
making this embodiment particularly useful in cases such
as those where it is not possible for the communication
mode to be determined simply from the CIR in each
communication terminal.
A base station according to this embodiment and a
communication terminal according to this embodiment will
be described below. FIG.10 is a block diagram showing
a configuration of a base station according to Embodiment
4 ofthe present invention. In the following description,
parts identical to those in FIG. 2 are assigned the same
reference numerals as in FIG.2 and their detailed
explanations are omitted.
In FIG.10, a demodulator 701 demodulates the output
signal from a despreading section 113, and extracts a
signal that contains CIR information (hereinafter
referred to as "CIR signal"), which is output to an
allocation section 704.
A reception power calculation section 702 measures
the reception power of the despread CIR signal, which
is output to an unused CIR detection section 703 . In the
unused CIR detection section 703 is set a predetermined
threshold value in the same way as in Embodiment 1, and
a CIR signal of reception power lower than this threshold
value is detected, and the result of the detection is
output to the allocation section 704.
A despreading section 113, demodulator 701,
reception power calculation section 702, and unused CIR
detection section 703 are provided for each communication
terminal. From each demodulator 701 a CIR signal for the
corresponding communication terminal is output, and from
each unused CIR detection section 703 a detection result
for the corresponding communication terminal is output.
The allocation section 704 determines communication
resource allocation to each communication terminal based
on CIR information indicated by CIR signals excluding
CIR signals detected by the unused CIR detection sections
703 from among the CIR signals extracted by the
demodulators 701. Then, based on the determined
communication resource allocation, the allocation
section 704 notifies a buffer 102 for output of downlink
transmit data, and outputs the CIR information to a
communication mode determination section 705.
Based on the CIR information output from the
allocation section 704, the communication mode
determination section 705 determines the communication
mode, which indicates a combination of modulation method
and coding method, and outputs a signal indicating this
communication mode to a modulator 7 06 . In addition, based
on the determined communication mode, the communication
mode determination section 7 05 indicates the downlink
transmit data coding method to an adaptive coding section
103, and indicates the downlink transmit data modulation
method to an adaptive modulator 104. Modulator 706
modulates the signal indicating the communication mode
and outputs it to a spreading section 707. Spreading
section 707 spreads the output signal from modulator 706
and outputs the resulting signal to a multiplexer 108.
FIG. 11 is a block diagram showing the configuration
of a communication terminal according to Embodiment 4
of the present invention. In the following description,
parts identical to those in FIG.3 are assigned the same
reference numerals as in FIG.3 and their detailed
explanations are omitted.
In FIG.11, a CIR information creation section 801
creates a CIR signal indicating a CIR measured by a CIR
measurement section 219, and outputs it to a modulator
802 and CIR information power controller 804. Modulator
802 modulates the CIR signal and outputs it to a spreading
section 803. Spreading section 803 spreads the output
signal from modulator 802 and outputs the spread signal
to the CIR information power controller 804. The CIR
information power controller 804 refers to a transmission
power table 805 that shows the correspondence between
CIR level and transmission power, and controls the CIR
signal transmission power based on the transmission power
of a pilot signal output from a pilot power controller
209, and outputs the CIR signal that has undergone
transmission power control to a multiplexer 210.
A despreading section 807 despreads the baseband
signal using the spreading code used to spread the signal
indicating the communication mode, and outputs the
despread signal to a communication mode detection section
808. The communication mode detection section 808
demodulates the output signal from despreading section
807 and detects the communication mode. Then, based on
the detected communication mode, the communication mode
detection section 808 indicates the downlink receive data
demodulation method to an adaptive demodulator 216 and
indicates the downlink receive data decoding method to
an adaptive decoding section 217.
Next, the procedure for transmission/reception of
signals between the base station shown in FIG.10 and the
communication terminal shown in FlG.ll will be described.
First, in the communication terminal shown in FIG. 11,
the CIR of the pilot signal output from despreading section
218 is measured by the CIR measurement section 219, and
a CIR signal is created by the CIR information creation
section 801.
The CIR signal is modulated by modulator 802 , spread
by spreading section 803 , and output to the CIR information
power controller 804. In the transmission power table
805, the correspondence between CIR level and CIR signal
transmission power is shown in the same way as in Embodiment
1, set so that the CIR signal transmission power increases
in proportion to the level of the CIR. That is to say,
in the settings in transmission power table 805, as in
Embodiment 1, the better the downlink channel quality
indicated by a CIR signal, the higher is the transmission
power. Also, as in Embodiment 1, the CIR signal
transmission power values set in the transmission power
table 805 are expressed as a ratio to the pilot signal
transmission power.
In the CIR information power controller 804, the
CIR signal transmission power is obtained by having the
transmission power of the pilot signal output from the
pilot power controller 209 adjusted in accordance with
the ratios set in the transmission power table 805. Then,
in the CIR information power controller 804, the
transmission power of the CIR signal output from spreading
section 803 is adjusted to this obtained transmission
power, and a CIR signal that has been subjected to
transmission power control is output to the multiplexer
210.
The CIR signal that has undergone transmission power
control is multiplexed with the pilot signal by the
multiplexer 210, frequency-converted to radio frequency
by a transmit RF section 211, and transmitted to the base
station as a radio signal from anantenna 213 via aduplexer
212.
In the base station shown in FIG.10, the output
signal from the despreading section 113 is demodulated
by demodulator 701, and the demodulated CIR signal is
extracted and output to the allocation section 704. In
the reception power calculation section 702, the
reception power of the despread CIR signal is measured,
and is output to the unused CIR detection section 703.
The lowest reception power at which an error does not
occur in a CIR signal indicating that downlink channel
quality is poorest has been set beforehand in the unused
CIR detection section 703 as a threshold value, as in
Embodiment 1. Then, in the unused CIR detection section
703, a CIR signal of reception power lower than this
threshold value is detected, and the detection result
is output to the allocation section 704. A CIR signal
detected by the unused CIR detection section 703 is a
CIR signal that is not used by the allocation section
704 in determining communication resource allocation.
In the allocation section 704, communication
resource allocation to each communication terminal is
determined based on the CIR shown by CIR signals remaining
after CIR signals detected by the unused CIR detection
section 703 have been excluded from the CIR signals
extracted by the demodulator 701, and CIR information
is output to the communication mode determination section
705.
In the communication mode determination section 7 05,
the communication mode is determined based on CIR
information output from the allocation section 704, and
a signal indicating this communication mode is output
to modulator 706. The signal indicating the
communication mode is modulated by modulator 706 , spread
by spreading section 707, multiplexed with transmit data
and the pilot signal in the multiplexer 108,
frequency-converted to radio frequency by the transmit
RF section 109, and transmitted to the communication
terminal as a radio signal from an antenna 111 via a
duplexer 110.
In the communication terminal shown in FIG.11, a
baseband signal is despread by despreading section 807,
and the despread signal is output to the communication
mode detection section 808. In the communication mode
detection section 808 , the output signal from despreading
section 807 is demodulated and the communication mode
is detected, and based on the detected communication mode,
the downlink receive data demodulation method is
indicated to the adaptive demodulator 216 andthe downlink
receive data decoding method is indicated to the adaptive
decoding section 217.
Thus , according to this embodiment, as in Embodiment
1, the better the downlink channel quality indicated by
a CIR signal, the higher is the transmission power at
which transmission is performed, and therefore it is
possible to reduce the error occurrence rate of CIR
information for which the probability of use by a base
station is high. By this means it is possible to reduce
the possibility of communication resource allocation
being determined based on erroneous CIR information, and
so to prevent a fall in downlink throughput.
Also, according to this embodiment, as in Embodiment
1, a CRI signal of reception power lower than the lowest
reception power at which a CIR signal indicating that
downlink channel quality is poorest is not received
erroneously is excluded, and therefore, even though a
CIR signal indicating that downlink channel quality is
poor is transmitted at lower transmission power than in
a conventional system, it is possible to prevent
communication resource allocation from being determined
based on erroneous CIR information.
A base station according to this embodiment may also
be configured as shown in FIG.12. FIG.12 is a block
diagram showing another configuration of a base station
according to Embodiment 4 of the present invention. That
is to say, a base station may be configured in such a
way that the reception power calculation section 702 and
unused CIR detection section 703 shown in FIG.10 are
replaced by a likelihood calculation section 901 and
unused CIR detection section 902. In the following
description, parts identical to those in FIG.10 are
assigned the same reference numerals as in FIG.10 and
their detailed explanations are omitted.
In FIG.12, the likelihood calculation section 901
calculates a likelihood that indicates the probable
degree of certainty of a CRI signal, and outputs the
calculation result to the unused CIR detection section
902. The lowest likelihood at which an error does not
occur in a CIR signal indicating that downlink channel
quality is poorest has been set beforehand in the unused
CIR detection section 902 as a threshold value. Then,
in the unused CIR detection section 902, a CIR signal
with a likelihood lower than this threshold value is
detected, and the detection result is output to the
allocation section 704.
In this way the same effect as described above is
also obtained when a base station according to this
embodiment is configured as shown in FIG.12.
(Embodiment 5)
In a communication terminal according to Embodiment
5 of the present invention, the better the downlink channel
quality indicated by a CIR signal, the larger is the code
word minimum distance of the code word to which that CIR
signal is converted with respect to other CIR signal code
words before being transmitted.
FIG. 13 is a block diagram showing the configuration
of a communication terminal according to Embodiment 5
of the present invention. As shown in this figure, a
communication terminal according to this embodiment is
configured in such a way that the modulator 802, spreading
section 803, CIR information power controller 804, and
transmission power table 805 shown in FIG. 11 are replaced
by a code word selector 1001, code word table 1002,
modulator 1003, and spreading section 1004. In the
following description, parts identical to those in FIG. 11
are assigned the same reference numerals as in FIG.11
and their detailed explanations are omitted.
The code word selector 1001 refers to the code word
table 1002, converts a CIR signal created by the CIR
information creation section 801 to a predetermined code
word, and outputs it to modulator 1003. Modulator 1003
modulates the code word and outputs it to spreading section
1004. Spreading section 1004 spreads the output signal
from modulator 1003 and outputs the resulting signal to
a multiplexer 210.
Next, the operation of a communication terminal
according to this embodiment will be described.
In the same way as in above-described Embodiment
2, the code word table 1002 shows the correspondence
between CIR level and code words after CIR signal
conversion, set so that the higher the CIR level, the
larger is the code word minimum distance of the code word
to which the CIR signal is converted. That is to say,
in the settings in the code word table 1002, the better
the downlink channel quality indicated by a CIR signal,
the larger is the code word minimum distance of the code
word to which the CIR signal is converted.
In the code word selector 1001, a CIR signal output
from the CIR information creation section 801 is converted
to a code word set in the code word table 1002, and output
to modulator 1003. Following conversion, the code word
is modulated by modulator 1003 and spread by spreading
section 1004. The spread code word is multiplexed with
a pilot signal by a multiplexer 210, frequency-converted
to radio frequency by a transmit RF section 211, and
transmitted to the base station as a radio signal from
an antenna 213 via a duplexer 212.
Thus , according to this embodiment, as in Embodiment
2, the better the downlink channel quality indicated by
a CIR signal, the larger is the code word minimum distance
of the code word to which that CIR signal is converted
with respect to other CIR signal code words before being
transmitted, and therefore it is possible to reduce the
error occurrence rate of CIR information for which the
probability of use by a base station is high. By this
means it is possible to reduce the possibility of
communication resource allocation being determined based
on erroneous CIR information, and so to prevent a fall
in downlink throughput.
Also, according to this embodiment, as in Embodiment
2, it is possible to reduce the error occurrence rate
of CIR information for which the probability of use by
a base station is high without increasing CIR signal
transmission power, thereby making it possible to reduce
the possibility of communication resource allocation
being determined based on erroneous CIR information
without increasing communication terminal power
consumption.
Moreover, according to this embodiment, as in
Embodiment 2, it is possible to change the degree of
insusceptibility to errors of code words corresponding
to CIR signals while keeping the code length of code words
constant, and therefore it is not necessary to provide
a plurality of demodulation systems in accordance with
different code lengths in a base station, thus enabling
the apparatus configuration of a base station to be
simplified.
(Embodiment 6)
A communication terminal according to Embodiments
6 to 8 of the present invention transmits with less
susceptibility to errors in the propagation path in
proportion to information for which the amount of change
is large within CIR information. In other words, a
communication terminal according to Embodiments 6 to 8
of the present invention transmits with less
susceptibility to errors in the propagation path in
proportion to information that indicates a broad value
within CIR information.
The meaning of "information for which the amount
of change is large" and "information that indicates a
broad value" here can be illustrated by a specific example.
If a CIR value is indicated by a value with a decimal
fraction (such as 8.7 dB), then the above-mentioned
information refers to the integer part (here, "8"). In
this case, since the amount of change per unit of the
integer part is 1 dB, while the amount of change per unit
of the fractional part is 0.1 dB, the integer part is
"information for which the amount of change is large".
Therefore, if an integer part is received erroneously
by a base station, the degree of error is large compared
with the case where a fractional part is received
erroneously, and the probability of an erroneous
communication mode being determined is higher—that is
to say, the probability of downlink throughput falling
is higher.
Also, CIR information is normally converted to a
code word with a limited number of bits before being
transmitted to a base station, and there are also limits
on the transmission power and spreading code spreading
factor that can be used in transmitting CIR information.
There are thus limits to making CIR information overall
insusceptible to errors, and it is difficult to do so.
Thus, in Embodiments 6 to 8 of the present invention,
within the above-described limitations on transmission
of CIR information, transmission is performed with
insusceptibility to errors in the propagation path made
proportional to "information for which the amount of
change is large" within the above limitations so that,
at least "information for which the amount of change is
large" (that is, "information that indicates a broad
value") of CIR information is received correctly.
A communication terminal according to Embodiment
6 of the present invention is described below. A
communication terminal according to Embodiment 6 of the
present invention performs conversion to, and transmits,
a code word with a code length proportional to the value
of the upper digit in a CIR value.
FIG. 14 is a block diagram showing the configuration
of a communication terminal according to Embodiment 6
of the present invention. In the following description,
parts identical to those in FIG. 11 are assigned the same
reference numerals as in FIG.11 and their detailed
explanations are omitted.
in FIG.14, a CIR signal creation section 1101
converts a CIR value measured by a CIR measurement section
219 to a code word and creates a CIR signal, and outputs
the created CIR signal to a multiplexer 210. At this time,
the CIR signal creation section 1101 creates a CIR signal
by performing conversion to a code word with a code length
proportional to the value of the upper digit in the CIR
value.
Next, the configuration of the CIR signal creation
section 1101 will be described. FIG. 15 is a block diagram
showing the configuration of the CIR signal creation
section of a communication terminal according to
Embodiment 6 of the present invention.
In FIG.15, an upper digit information generation
section 1201 outputs the value of the upper digit in the
CIR value output from the CIR measurement section 219
to a 6-bit coding section 1203 . A lower digit information
generation section 1202 outputs the value of the lower
digit in the CIR value output from the CIR measurement
section 219 to a 4-bit coding section 1204. To give a
specific example, if the CIR value output from the CIR
measurement section 219 is 8.7 dB, the upper digit
information generation section 1201 outputs the value
of the integer part, "8", to the 6-bit coding section
1203, and the lower digit information generation section
1202 outputs the value of the fractional part, "7", to
the 4-bit coding section 1204.
The 6-bit coding section 1203 converts the value
output from the upper digit information generation
section 1201 (here, "8") to a 6-bit code word, and outputs
the 6-bit code word to a time multiplexer 1205 . The 4-bit
coding section 1204 converts the value output from the
lower digit information generation section 1202 (here,
"7") to a 4-bit code word, and outputs the 4-bit code
word to the time multiplexer 1205. It is herein assumed
that the number of bits that can be used to indicate a
CIR value is ten.
The time multiplexer 1205, by storing the 6-bit code
word in the first half of a slot and storing the 4-bit
codeword inthe following latter half of the slot, performs
time multiplexing of the code word for the integer part
of the CIR value (that is, the code word corresponding
to the value of the upper digit) and the code word for
the fractional part of the CIR value (that is, the code
word corresponding to the value of the lower digit) . The
time multiplexer 1205 then outputs the time-multiplexed
10-bit code word to a modulator 1206 as a CIR signal.
It is herein assumed that one slot is composed of 10 bits,
with the integer part of a CIR value represented by the
preceding 6 bits and the fractional part of a CIR value
represented by the succeeding 4 bits.
The modulator 1206 modulates the CIR signal and
outputs it to the spreading section 1207. The spreading
section 1207 spreads the output signal from the modulator
1206 and outputs the resulting signal to the multiplexer
210.
Next, the operation of a communication terminal with
the above configuration will be described.
In the 6-bit coding section 1203, the value of the
upper digit in the CIR value (here, "8") is converted
to a 6-bit code word, and the value of the lower digit
in the CIR value (here, "7" ) is converted to a 4-bit code
word.
As the number of different code words that can be
represented by 6 bits is 26, and the number of different
code words that can be represented by 4 bits is 24, the
code word minimum distance between code words can be made
larger for code words represented by 6 bits. Therefore,
a code word represented by 6 bits is less susceptible
to being mistaken for another code word than a code word
represented by 4 bits . That is to say , in this embodiment,
the value of the upper digit of a CIR value is less
susceptible to errors.
Thus, with a communication terminal according to
this embodiment, within the limitation of 10 bits
available to indicate a CIR value, by performing
conversion to a code word of a code length proportional
to the value of the upper digit in a CIR value, it is
possible to perform transmission with insusceptibility
to errors made proportional to the value of the upper
digit for which the amount of change is large. By this
means, even if an error should occur in a CIR signal in
the propagation path, the probability of being able to
perform reception correctly at the base station is
proportionally higher according to the value of the upper
digit in a CIR value, and the degree of error in CIR values
can be kept low. Thus, it is possible to reduce the
possibility of an erroneous communication mode being
determined in the base station.
In this embodiment, a case has been described where
the upper digit value is converted to a 6-bit code word
and the lower digit value is converted to a 4-bit code
word. However, as long as the number of bits of the code
word corresponding to the upper digit value is greater
than the number of bits of the code word corresponding
to the lower digit value, there are no particular
limitations on these numbers of bits.
(Embodiment 7)
A communication terminal according to Embodiment
7 of the present invention transmits with transmission
power increased in proportion to the value of the upper
digit in a CIR value.
A communication terminal according to this
embodiment differs from a communication terminal
according to Embodiment 6 only in the internal
configuration of the CIR signal creation section 1101,
and therefore only the CIR signal creation section 1101
will be described in the following description.
FIG. 16 is a block diagram showing the configuration
of the CIR signal creation section of a communication
terminal according to Embodiment 7 of the present
invention. In the following description, parts
identical to those in FIG.15 are assigned the same
reference numerals as in FIG.15 and their detailed
explanations are omitted.
The CIR signal creation section 1101 shown in FIG. 1 6
converts a CIR value measured by a CIR measurement section
219 to a code word, and then creates a CIR signal,
increasing transmission power in proportion to the value
of the upper digit.
In FIG. 16, a 5-bit coding section 1301 converts the
value output from an upper digit information generation
section 1201 to a 5-bit code word and outputs the 5-bit
code word to a modulator 1303, and a 5-bit coding section
1302 converts the value output from a lower digit
information generation section 1202 to a 5-bit code word
and outputs the 5-bit code word to a modulator 1304. Thus,
in this embodiment, both the upper digit value and the
lower digit value are converted to 5-bit code words, and
therefore there is no difference between them in
insusceptibility to errors from a code word standpoint.
Modulator 1303 modulates the code word output from
5-bit coding section 1301, and outputs it to an upper
digit spreading section 1305. Modulator 1304 modulates
the code word output from 5-bit coding section 1302, and
outputs it to a lower digit spreading section 1306.
The upper digit spreading section 1305 spreads the
output signal from modulator 1303, and outputs the spread
signal to an upper digit power controller 1307 . The lower
digit spreading section 1306 spreads the output signal
from modulator 1304, and outputs the spread signal to
a lower digit power controller 1308. At this time, the
upper digit spreading section 1305 and lower digit
spreading section 1306 perform their respective spreading
processing using different spreading codes of the same
spreading factor. That is to say, the upper digit value
of the CIR value and the lower digit value of the CIR
value are spread using different spreading codes that
have the same spreading factor.
Based on the transmission power of a pilot signal
output from a pilot power controller 209, the upper digit
power controller 1307 controls the transmission power
of the signal indicating the upper digit value of the
CIR value, and outputs the signal that has undergone
transmission power control to a code multiplexer 1309.
Similarly, based on the transmission power of the pilot
signal output from the pilot power controller 209, the
lower digit power controller 1308 controls the
transmission power of the signal indicating the lower
digit value of the CIR value, and outputs the signal that
has undergone transmission power control to the code
multiplexer 1309 . The actual transmission power control
method will be described later herein.
The code multiplexer 1309 multiplexes the signal
indicating the upper digit value of the CIR value and
the signal indicating the lower digit value of the CIR
value in the same time slot. That is to say, the code
multiplexer 1309 performs code multiplexing of the signal
indicating the upper digit value and the signal indicating
the lower digit value.
Next, the operation of a communication terminal with
the above configuration will be described.
In the upper digit power controller 1307, a signal
indicating the upper digit value of a CIR value is adjusted
to a transmission power whose only predetermined value
is higher than the pilot signal transmission power. In
the lower digit power controller 1308 , a signal indicating
the lower digit value of the CIR value is adjusted to
a transmission power whose only predetermined value is
lower than the pilot signal transmission power. That is
to say, the transmission power is increased in proportion
to the value of the upper digit in the CIR value.
Thus, a communication terminal according to this
embodiment can transmit with insusceptibility to errors
made proportional to the upper digit value for which the
amount of change is large by transmitting with
transmission power increased in proportion to the upper
digit value of a CIR value. By this means, even if an
error should occur in a CIR signal in the propagation
path, the probability of being able to perform reception
correctly at the base station is proportionally higher
according to the value of the upper digit in a CIR value,
and the degree of error in CIR values can be kept low.
Thus, it is possible to reduce the possibility of an
erroneous communication mode being determined in the base
station.
Also, in this embodiment, by increasing
transmission power of the upper digit value compared with
conventional CIR signal transmission power (here, the
pilot signal transmission power), and decreasing
transmission power of the lower digit value by the amount
by which it is increased for the upper digit value, giving
a total transmission power increase/decrease value of
±0 dB, the overall CIR signal transmission power is kept
the same as conventional CIR signal transmission power.
Thus, according to this embodiment, it is possible to
perform transmission with insusceptibility to errors made
proportional to the upper digit value while keeping CIR
signal transmission power the same as in a conventional
system. That is to say, it is possible to perform
transmission with insusceptibility to errors made
proportional to the upper digit value without reducing
uplink capacity compared with a conventional system.
(Embodiment 8)
A communication terminal according to Embodiment
8 of the present invention transmits with spreading
performed using a spreading code with a higher spreading
factor in proportion to the value of the upper digit in
a CIR value.
A communication terminal according to this
embodiment differs from a communication terminal
according to Embodiment 6 or 7 only in the internal
configuration of the CIR signal creation section 1101,
and therefore only the CIR signal creation section 1101
will be described in the following description.
FIG. 17 is a block diagram showing the configuration
of the CIR signal creation section of a communication
terminal according to Embodiment 8 of the present
invention. In the following description, parts
identical to those in FIG.15 or FIG.16 are assigned the
same reference numerals as in FIG. 15 or FIG. 16 and their
detailed explanations are omitted.
The CIR signal creation section 1101 shown in FIG. 1 7
converts a CIR value measured by a CIR measurement section
219 to a code word, and then creates a CIR signal, with
spreading performed using a spreading code with a higher
spreading factor in proportion to the value of the upper
digit.
In FIG.17, an upper digit spreading section 1401
spreads the output signal from modulator 1303 and outputs
the resulting signal to a time multiplexer 1205, and a
lower digit spreading section 1402 spreads the output
signal from modulator 1304 and outputs the spread signal
to the time multiplexer 1205. At this time, the upper
digit spreading section 1401 performs spreading
processing with a spreading code of the same kind as used
by the lower digit spreading section 1402 and with a higher
spreading factor than that of the lower digit spreading
section 1402. That is to say, the upper digit value of
the CIR value is spread with a higher spreading factor
than the lower digit value . As a result, insusceptibility
to errors in the propagation path is proportional to the
upper digit value.
Thus, a communication terminal according to this
embodiment can transmit with insusceptibility to errors
made proportional to the upper digit value for which the
amount of change is large by transmitting with spreading
performed using a spreading code with a higher spreading
factor in proportion to the value of the upper digit in
a CIR value. By this means , even if an error should occur
in a CIR signal in the propagation path, the probability
of being able to perform reception correctly at the base
station is proportionally higher according to the value
of the upper digit in a CIR value, and the degree of error
in CIR values can be kept low. Thus, it is possible to
reduce the possibility of an erroneous communication mode
being determined in the base station.
Also, in this embodiment, the spreading factor for
the upper digit value is increased compared with a
conventional CIR signal spreading factor, and the
spreading factor for the lower digit value is decreased
by the amount by which it is increased for the upper digit
value. By this means, the amount of data sent in one slot
is kept the same as for a conventional CIR signal. Thus,
according to this embodiment, it is possible to perform
transmission with insusceptibility to errors made
proportional to the upper digit value without reducing
the amount of data sent in one slot.
It is also possible to implement the present
invention by combining a communication terminal according
to above-described Embodiment 1 and a communication
terminal according to above-described Embodiment 2.
Moreover, it is also possible to implement the present
invention by combining a communication terminal according
to above-described Embodiment 4 and a communication
terminal according to above-described Embodiment 5.
Furthermore, it is also possible to implement the present
invention by combining the respective communication
terminals according to above-described Embodiments 6 to
8. In addition, it is also possible for the transmission
power table provided in a communication terminal
according to above-described Embodiment 4 and the code
word table provided in a communication terminal according
to above-described Embodiment 5 to be rewritten as
appropriate based on a control signal from the base station,
in the same way as in above-described Embodiment 3.
Also, in above-described Embodiments 1 to 8, a case
has been described where a pilot signal is
time-multiplexed, but above-described Embodiments 1 to
8 are not limited to this, and can also be applied to
a case where a pilot signal is code-multiplexed.
Moreover, in above-described Embodiments 1 to 8,
a CIR has been used as a value that indicates pilot signal
reception quality, but this is not a limitation, and any
value may be used as long as it is a value that indicates
reception quality.
Furthermore, in above-described Embodiments 1 to
5, the predetermined threshold value set in the unused
DRC detection section or the unused CIR detection section
is assumed to be a fixed value, but a configuration may
also be used whereby the threshold value is varied
adaptively in accordance with the DRC signal error rate
or CIR signal error rate.
In addition, in above-described Embodiments 6 to
8, either time multiplexing or code multiplexing may be
used when multiplexing code words.
Also, in above-described Embodiments 6 to 8, an
example has been given in which a CIR value is represented
by one integer-part digit and one fractional-part digit.
However, this is not a limitation, and above-described
Embodiments 6 to 8 may all be implemented for CIR values
represented by a plurality of digits.
Moreover, in above-described Embodiments 6 to 8,
the value of the upper digit of a CIR value has been
described as "information for which the amount of change
is large". However, "information for which the amount
of change is large" does not necessarily correspond to
the size of a digit. For example, if a method is used
whereby a CIR value is represented by an integer by first
indicating a broad value of 0 db, 2 dB, 4 dB, 6 dB ... changing
by 2 dB at a time, and adding information indicating the
presence or absence of an increment of 1 dB for that broad
value, a value changing by 2 dB at a time is "information
for which the amount of change is large". With this method,
to represent a CIR value of 7 dB, for example, CIR
information that includes information indicating 6 dB
and information indicating that there is an increment
of 1 dB is transmitted to the base station. At this time,
the communication terminal apparatus transmits the
information indicating 6 dB with greater insusceptibility
to errors than the information indicating that there is
an increment of 1 dB, in the same way as in above-described
Embodiments 6 to 8.
As described above, according to the present
invention it is possible to prevent a fall in downlink
throughput in a communication system in which
communication resources are allocated to communication
terminals based on downlink channel quality.
This application is based on Japanese Patent
Application No.2000-234420 filed on August 2, 2000, and
Japanese Patent Application No.2000-285405 filed on
September 20, 2000, entire content of which is expressly
incorporated by reference herein.
We Claim
1. A communication terminal apparatus that performs radio communication
with a base station apparatus in a communication system having a
plurality of communication terminal apparatuses, downlink communication
resource being allocated to each of said plurality of communication
terminal apparatuses, said communication terminal apparatus comprising-.
a measuring section (219) that measures downlink channel quality,
and
a transmitter (211) that transmits a notification signal having
information indicating the measured downlink channel quality to a
base station apparatus,
wherein said transmitter (211) is adapted to protect the
information in the notification signal by making the information less
susceptible to errors in a propagation path.
2. The communication terminal apparatus as claimed in claim 1, wherein said
transmitter (211) is adapted to increase / decrease the protection level of
said notification signal in case the measured downlink channel quality
increases / decreases.
3. The communication terminal apparatus as claimed in claim 1, comprising a
controller (209) that controls the transmission power of a pilot signal,
wherein said transmitter (211) is adapted to transmit said
notification signal at a transmission power level higher than the
transmission power level of the pilot signal in case the measured
downlink channel quality is good,.|nd at a transmission power level
lower than the transmission power level of the pilot signal in case
the measured down link channel quality is poor.
4. The communication terminal apparatus as claimed in claim 3, comprising a
rewriting section (603) that rewrites the contents of a table indicating
information of the notification signal and its corresponding transmission
power offset in accordance with a control signal from a base station
apparatus,
wherein said transmitter (211) is adapted to adjust the power level
for the transmission of the information in the notification signal
based on said table.
5. The communication terminal apparatus as claimed in claim 1, wherein said
transmitter (211) is adapted to increase / decrease the minimum distance
of code words representing different channel quality levels in case the
measured downlink channel quality increases / decreases.
6. The communication terminal apparatus as claimed in claim 5, comprising a
rewriting section (603) that rewrites the contents of a table indicating
information of said notification signal and its corresponding codeword in
accordance with a control signal from a base station apparatus,
wherein said transmitter (211) is adapted to convert the
information of the notification signal to a predetermined codeword
based on said table.
7. The communication terminal apparatus as claimed in claim 2, comprising a
determination section (201) that determines a communication mode
defining a combination of modulation method and coding method based
on channel quality,
wherein said transmitter (211) is adapted to indicate the
communication mode using the notification signal.
8. A communication terminal apparatus that performs radio communication
with a base station apparatus in a communication system having a
plurality of communication terminal apparatuses, downlink communication
resource being allocated to each of said plurality of communication
terminal apparatuses, said communication terminal apparatus comprising:
a measuring section (219) that measures reception quality of a
pilot signal to output information having a plurality of bits that
indicate the reception quality;
a coding section (1203, 1204) that encodes the information to
obtain a code word; and
a transmitter (211) that transmits the code word;
wherein said coding section (1203,1204) is adapted to protect the
information by encoding the most significant bit of the plurality of
bits, thereby making the most significant bit less susceptible to
errors in a propagation path than other bits of the plurality of bits.
9. A base station apparatus that performs radio communication with at least
one communication terminal apparatus in a communication system, said
base station apparatus comprising:
a receiver (112) that receives a notification signal transmitted from
the communication terminal apparatus as claimed in claim 1,
a measurement section (115) that measures reception powers of
the notification signals,
a detector (116) that detects reception powers of notification
signals being larger than a predetermined threshold value, and
a determination section (101) that determines an allocation of
downlink communication resource using information in said
notification signals for which a reception power higher than the
predetermined threshold has been detected.
10.The base station apparatus as claimed in claim 9, comprising:
a calculator (501) that calculates a detection rate of said detector,
and
a transmitter (109) that transmits a control signal instructing the
communication terminal apparatus to rewrite a table based on a
result of comparison of a rate of detection and a predetermined
threshold value.
11. A base station apparatus that performs radio communication with at least
one communication terminal apparatus in a communication system, said
base station apparatus comprising;
a receiver (112) that receives a notification signal transmitted from
the communication terminal apparatus as claimed in claim 1,
a measurement section (301) that measures the likelihood of the
notification signal, the likelihood indicates the reliability of the
information of the notification signal,
a detector (302) that detects a notification signal whose likelihood
is larger than the predetermined threshold value, and
a determination section (101) that determines an allocation of
downlink communication resource using information of the
notification signal whose likelihood is larger than said
predetermined threshold value.
12.The base station apparatus as claimed in claim 11, comprising:
a calculator (501) that calculates a detection rate of said detector,
and
a transmitter (109) that transmits a control signal instructing the
communication terminal apparatus to rewrite a table based on a
result of comparison of the detection rate and a predetermined
threshold value.
13.A radio communication method between a base station apparatus and at
feast one communication terminal apparatus in a communication system,
the method comprising:
a communication terminal apparatus measures downlink channel
quality and transmits a notification signal having information
indicating the measured downlink channel quality to a base station
apparatus, and
the base station apparatus allocates downlink communication
resource to the communication terminal apparatus based on the
information in said notification signal,
wherein the communication terminal apparatus protects the
information in the notification signal by making the information less
susceptible to errors in a propagation path.
14.The radio communication method as claimed in claim 13, wherein the
communication terminal apparatus increases / decreases the protection
level of said notification signal in case the measured downlink channel
quality increases / decreases.
15.The radio communication method as claimed in claim 13, wherein the
communication terminal apparatus controls the transmission power of a
pilot signal and transmits said notification signal at a transmission power
level higher than the transmission power level of the pilot signal in case
the measured downlink channel quality is good, and at a transmission
power level lower than the transmission power level of the pilot signal in
case the measured downlink channel quality is poor.

A communication mode determining section (201) determines the communication mode on the basis of the CIR measured by a CIR measuring section (219). The DRC signal generator (202) generates a DRC signal of the number corresponding to the communication mode. A DRC power control section (205) refers to a transmission power table (206) showing the correspondence between the DRC number and the transmission power and increases the transmission power more for a DRC signal having a better line quality of the downstream line on the basis of the transmission power of a pilot signal outputted from a pilot power control section (209).

Documents:

in-pct-2002-431-kol-abstract.pdf

in-pct-2002-431-kol-claims.pdf

in-pct-2002-431-kol-correspondence.pdf

in-pct-2002-431-kol-description (complete).pdf

in-pct-2002-431-kol-drawings.pdf

in-pct-2002-431-kol-examination report.pdf

in-pct-2002-431-kol-form 1.pdf

in-pct-2002-431-kol-form 18.pdf

in-pct-2002-431-kol-form 2.pdf

in-pct-2002-431-kol-form 3.pdf

in-pct-2002-431-kol-form 5.pdf

in-pct-2002-431-kol-gpa.pdf

in-pct-2002-431-kol-granted-abstract.pdf

in-pct-2002-431-kol-granted-claims.pdf

in-pct-2002-431-kol-granted-correspondence.pdf

in-pct-2002-431-kol-granted-description (complete).pdf

in-pct-2002-431-kol-granted-drawings.pdf

in-pct-2002-431-kol-granted-examination report.pdf

in-pct-2002-431-kol-granted-form 1.pdf

in-pct-2002-431-kol-granted-form 13.pdf

in-pct-2002-431-kol-granted-form 18.pdf

in-pct-2002-431-kol-granted-form 2.pdf

in-pct-2002-431-kol-granted-form 3.pdf

in-pct-2002-431-kol-granted-form 5.pdf

in-pct-2002-431-kol-granted-gpa.pdf

in-pct-2002-431-kol-granted-others.pdf

in-pct-2002-431-kol-granted-reply to examination report.pdf

in-pct-2002-431-kol-granted-specification.pdf

in-pct-2002-431-kol-granted-translated copy of priority document.pdf

in-pct-2002-431-kol-reply to examination report.pdf

in-pct-2002-431-kol-specification.pdf

in-pct-2002-431-kol-translated copy of priority document.pdf


Patent Number 236140
Indian Patent Application Number IN/PCT/2002/431/KOL
PG Journal Number 40/2009
Publication Date 02-Oct-2009
Grant Date 30-Sep-2009
Date of Filing 03-Apr-2002
Name of Patentee PANASONIC CORPORATION
Applicant Address 1006, OAZA KADOMA, KADOMA-SHI, OSAKA
Inventors:
# Inventor's Name Inventor's Address
1 MIYOSHI KENICHI 11-4-1305, NOKENDAIHIGASHI, KANAZAWA-KU, YOKOHAMA-SHI, KANAGAWA 236-0058
2 KATO OSAMU 5-45 G302, SHONANTAKATORI, YOKOSUKA-SHI, KANAGAWA 237-0066
3 AIZAWA JUNICHI 9-20, SAKAIGIHONCHO, HODOGAYA-KU, YOKOHAMA-SHI, KANAGAWA 240-0033
PCT International Classification Number H04Q 7/38,H04B 7/26
PCT International Application Number PCT/JP2001/06654
PCT International Filing date 2001-08-02
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2000-234420 2000-08-02 Japan
2 2000-285405 2000-09-20 Japan