U.S. patent application number 13/090821 was filed with the patent office on 2011-08-11 for mobile communication system.
This patent application is currently assigned to PANASONIC CORPORATION. Invention is credited to Takahisa Aoyama, Katsuhiko Hiramatsu, Osamu Kato, Kenichi Miyoshi, Atsushi Sumasu.
Application Number | 20110195669 13/090821 |
Document ID | / |
Family ID | 26595457 |
Filed Date | 2011-08-11 |
United States Patent
Application |
20110195669 |
Kind Code |
A1 |
Miyoshi; Kenichi ; et
al. |
August 11, 2011 |
MOBILE COMMUNICATION SYSTEM
Abstract
A mobile communication system which is capable of, when carrying
out mobile communication using a shared channel, increasing in
efficiency of transmission timing of the data transmission rate
request value to prevent wasteful power consumption and hence
reduce power consumption. A mobile station apparatus of the mobile
communication system measures CIR of the received signal from a
base station apparatus at a CIR measuring section, and decides the
data transmission rate request value corresponding to the measured
CIR value at a rate request value deciding section. Also, it
detects an error of the received signal at a CRC section, and, when
no error is found, calculates a difference between the average data
transmission rate from a base station apparatus and the data
transmission request value at a rate request value transmission
controlling section. Then, it transmits the data transmission rate
request value to the base station apparatus only when the obtained
difference is larger than a threshold value.
Inventors: |
Miyoshi; Kenichi;
(Yokohama-shi, JP) ; Hiramatsu; Katsuhiko;
(Yokosuka-shi, JP) ; Aoyama; Takahisa;
(Yokosuka-shi, JP) ; Sumasu; Atsushi;
(Yokosuka-shi, JP) ; Kato; Osamu; (Yokosuka-shi,
JP) |
Assignee: |
PANASONIC CORPORATION
Osaka
JP
|
Family ID: |
26595457 |
Appl. No.: |
13/090821 |
Filed: |
April 20, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12495673 |
Jun 30, 2009 |
7953029 |
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13090821 |
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11049728 |
Feb 4, 2005 |
7573838 |
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12495673 |
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10069375 |
Feb 25, 2002 |
6889041 |
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PCT/JP2001/005395 |
Jun 25, 2001 |
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11049728 |
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Current U.S.
Class: |
455/67.11 |
Current CPC
Class: |
H04W 28/22 20130101;
H04W 52/0245 20130101; H04W 72/1284 20130101; H04W 52/24 20130101;
Y02D 30/70 20200801; H04W 52/0229 20130101; Y02D 70/00 20180101;
H04W 52/0258 20130101; H04W 72/12 20130101; H04W 24/00 20130101;
H04W 52/26 20130101 |
Class at
Publication: |
455/67.11 |
International
Class: |
H04W 24/08 20090101
H04W024/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 26, 2000 |
JP |
2000-232268 |
Jul 5, 2000 |
JP |
2000-204222 |
Claims
1. A mobile station apparatus comprising: a receiver that receives
a signal from a base station; a measuring section that measures a
reception quality of the received signal; a determining section
that determines a reception quality value based on the reception
quality; and a transmitter that periodically transmits the
reception quality value to the base station and voluntarily
transmits the reception quality value to the base station before
the next periodic transmission when the previously transmitted
reception quality value is different from the current reception
quality value to be transmitted, wherein: the transmitter
voluntarily transmits no reception quality value to the base
station before the next periodic transmission when the previously
transmitted reception quality value is the same as the current
reception quality value to be transmitted.
2. A receiving method comprising: receiving a signal from a
transmitter; measuring a reception quality of the received signal;
determining a reception quality value based on the reception
quality; periodically transmitting the reception quality value to
the transmitter; and voluntarily transmitting the reception quality
value to the transmitter before the next periodic transmission when
the previously transmitted reception quality value is different
from the current request value, wherein: voluntary transmits no
reception quality value to the base station before the next
periodic transmission when the previously transmitted reception
quality value is the same as the current reception quality value.
Description
[0001] This is a continuation application of application Ser. No.
12/495,673 filed Jun. 30, 2009, which is a continuation application
of application Ser. No. 11/049,728 filed Feb. 4, 2005, which is a
continuation application of application Ser. No. 10/069,375 filed
Feb. 25, 2002, which is a national stage of PCT/JP2001/005395 filed
Jun. 25, 2001, which is based on Japanese Patent Application No.
2000-232268 filed Jun. 26, 2000, and Japanese Patent Application
No. 2000-204222 filed Jul. 5, 2000, the entire contents of each of
which are incorporated by reference herein.
TECHNICAL FIELD
[0002] The present invention relates to a mobile communication
system, and to a base station apparatus and a mobile station
apparatus constituting the same.
BACKGROUND ART
[0003] As one of the standards for the mobile communication system,
there is a standard called CDMA2000. To CDMA2000 is applied HDR
(High Data Rate) which uses a dedicated frequency band for data
communication in addition to a dedicated frequency band for voice
communication. In HDR, a shared channel in which the dedicated
frequency band (channel) for data communication is shared by a
plurality of users is used.
[0004] The shared channel is defined as a channel in which data
transmission rate (hereinafter, simply referred to as "rate") is
appropriately changeable, and the same frequency is used by a
plurality of mobile station apparatuses wherein only one mobile
station apparatus that has been selected by a base station
apparatus is permitted to use exclusively the frequency in
time-sharing mode to carry out data communication.
[0005] In a conventional mobile communication system, which uses
such shared channel as described above, first, a plurality of
mobile station apparatuses receive a pilot burst signal transmitted
from a base station apparatus. Then, each mobile station apparatus
measures CIR (Carrier to Interference Ratio), which represents the
reception quality, based on the received pilot burst signal, and
transmits a rate request value according to the CIR measurement
value to the base station apparatus. At this time, transmission of
the rate request value is carried out from every mobile station
apparatus within the communication area at the same timing. Then,
the base station apparatus, on receiving the rate request value
from each mobile station apparatus, selects a mobile station
apparatus to which data is to be transmitted based on the received
rate request values, and transmits the data to the relevant mobile
station apparatus at a rate of the rate request value received from
the selected mobile station apparatus.
[0006] However, in the conventional system, since the data is
transmitted only to the mobile station apparatus that has been
selected by the base station apparatus, the mobile station
apparatus, even when it transmits the rate request value, can not
receive the data unless it is selected by the base station
apparatus, and thus needs to transmit the rate request value
continuously until it is selected by the base station
apparatus.
[0007] That is to say, when the rate request value transmitted from
the mobile station apparatus is smaller than a rate assigned to the
data transmission by the base station apparatus, the relevant
mobile station apparatus is rarely selected but nevertheless needs
to transmit the rate request value continuously, thus resulting in
a problem of useless electric power consumption for that continuous
period of time. Since the power consumption for the transmission in
the mobile station apparatus is large, a battery runs out earlier
due to useless power consumption.
[0008] Further, when the mobile station apparatus is in a
standstill or moving at a low speed, the mobile station apparatus
transmits every time the same rate request value, even though CIR
fluctuates little. Therefore, in this case also, there is such a
problem of useless electric power consumption.
[0009] DISCLOSURE OF THE INVENTION
[0010] It is an object of the present invention to provide a mobile
communication system that is capable of, when carrying out mobile
communication using a shared channel, increasing in efficiency of
transmission timing of the data transmission rate request value to
prevent wasteful power consumption and hence reduce power
consumption.
[0011] According to an aspect of the invention, a mobile
communication system comprises a mobile station apparatus that
transmits data transmission rate request value, and a base station
apparatus that selects the mobile station apparatus to which data
is transmitted based on the data transmission rate request value
received from the mobile station apparatus and transmits data to
the selected mobile station apparatus at the data transmission rate
request value received from the selected mobile station apparatus,
wherein the mobile station apparatus comprises first receiving
means for receiving an average data transmission rate transmitted
from the base station apparatus, measuring means for measuring
quality of the received signal from the base station apparatus,
deciding means for deciding the data transmission rate request
value based on the reception quality measured by the measuring
means, first calculating means for calculating a difference between
the data transmission rate request value decided by the deciding
means and the average data transmission rate received by the first
receiving means, judging means for judging whether or not the
result of calculation by the first calculating means is equal to or
larger than a reference value, and first controlling means for
making the data transmission rate request value decided by the
deciding means he transmitted to the base station apparatus when it
is judged by the judging means that the result of calculation by
the first calculating means is equal to or larger than the
reference value, and wherein the base station apparatus comprises
second receiving means for receiving the data transmission rate
request value transmitted from the mobile station apparatus,
selecting means for selecting the mobile station apparatus to which
data is transmitted based on the data transmission rate request
value received by the second receiving means, second calculating
means for calculating an average of a data transmission rate for
transmitting data to the mobile station apparatus selected by the
selecting means as the average data transmission rate, and second
controlling means for making the average data transmission rate
calculated by the second calculating means be transmitted to the
mobile station apparatus.
[0012] According to another aspect of the invention, a mobile
communication system comprising a mobile station apparatus that
transmits data transmission rate request value, and a base station
apparatus that selects the mobile station apparatus to which data
is transmitted based on the data transmission rate request value
received from the mobile station apparatus and transmits data to
the selected mobile station apparatus at the data transmission rate
request value received from the selected mobile station apparatus,
wherein the mobile station apparatus comprises first measuring
means for measuring quality of the received signal from the base
station apparatus, deciding means for deciding the data
transmission rate request value based on the reception quality
measured by the first measuring means, first storing means for
storing the data transmission rate request value decided by the
deciding means, first judging means for comparing the previous data
transmission rate request value stored in the first storing means
and the latest data transmission rate request value, and judging
whether or not both thereof are different from each other, and
controlling means for making the latest data transmission rate
request value be transmitted to the base station apparatus when it
is judged by the first judging means that the previous data
transmission rate request value and the latest data transmission
rate request value are different from each other, and wherein the
base station apparatus comprises second measuring means for
measuring quality of the received signal from the mobile station
apparatus, receiving means for receiving the data transmission rate
request value transmitted from the mobile station apparatus, second
storing means for storing the data transmission rate request value
received by the receiving means by relating it to the mobile
station apparatus, second judging means for judging, when there is
any mobile station apparatus the data transmission rate request
value of which has not been received this time by the receiving
means, as for the relevant mobile station apparatus, whether or not
the reception quality measured by the second measuring means is
equal to or larger than a reference value, and control means for
using, when it is judged by the second judging means that the
measured value of the reception quality is equal to or larger than
the reference value, as for the relevant mobile station apparatus,
the previous data transmission rate request value stored in the
second storing means as the data transmission rate request value to
be used for selecting the mobile station apparatus to which data is
transmitted.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a block diagram illustrating a constitution of a
mobile communication system according to a first embodiment of the
present invention;
[0014] FIG. 2 is a block diagram illustrating a constitution of a
base station apparatus in the mobile communication system according
to the first embodiment of the present invention;
[0015] FIG. 3 is a block diagram illustrating a constitution of a
mobile station apparatus in the mobile communication system
according to the first embodiment of the present invention;
[0016] FIG. 4 is a block diagram illustrating a constitution of a
base station apparatus in a mobile communication system according
to a second embodiment of the present invention;
[0017] FIG. 5 is a block diagram illustrating a constitution of a
mobile station apparatus in the mobile communication system
according to the second embodiment of the present invention;
[0018] FIG. 6 is a diagram used for illustrating transmission
timing of the rate request value in the mobile station apparatus of
the mobile communication system according to the second embodiment
of the present invention; and
[0019] FIG. 7 is a diagram used for illustrating transmission
timing of the rate request value in a mobile station apparatus of a
mobile communication system according to a third embodiment of the
present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0020] Embodiments of the present invention will be described below
in detail with reference to accompanying drawings.
First Embodiment
[0021] FIG. 1 is a block diagram illustrating a constitution of a
mobile communication system according to a first embodiment of the
present invention.
[0022] This mobile communication system includes, as shown in FIG.
1, a base station apparatus 101 and a plurality of mobile station
apparatuses 102. The base station apparatus 101 and the mobile
station apparatus 102 carry out radio communication using a shared
channel in HDR applied to CDMA2000.
[0023] The base station apparatus 101 includes, as shown in FIG. 2,
an antenna 201 for transmitting/receiving common use, an RF (Radio
Frequency) section 202, a multiplexing section 203, four
modulating/spreading sections 204, 205, 206 and 207, a
despreading/demodulating section 208, a dedicated channel coding
section 209, a MAC (Medium Access Control) channel assembling
section 210, a TPC (Transmit Power Control) generating section 211,
a radio resource controlling section 212, an average rate
calculating section 214, a broadcast channel assembling section 215
and a buffering section 216.
[0024] The mobile station apparatus 102 includes, as shown in FIG.
3, an antenna 301 for transmitting/receiving common use, an RF
section 302, a despreading/demodulating section 303, a CRC (Cycle
Redundancy Check) section 304, a disassembling section 305, a CIR
(Carrier to Interference Ratio) measuring section 306, a rate
request value deciding section 307, a rate request value
transmission controlling section 308, a multiplexing section 309
and a modulating/spreading section 310.
[0025] Next, the operation of the mobile communication system
having the constitution as described above will be described.
[0026] First, the base station apparatus 10 modulates and spreads a
pilot burst signal in the modulating/spreading section 204.
[0027] Then, the modulated and spread pilot burst signal is
multiplexed with other various signals that have been modulated and
spread (for example, an average rate signal assigned to the shared
channel, which will be described later, etc.) in the multiplexing
section 203, subjected to predetermined transmission processing
such as up-conversion etc. in the RF section 202, and then
transmitted as a radio signal via antenna 201.
[0028] After that, the mobile station apparatus 102 receives via
antenna 301 the signal transmitted as a radio signal from the base
station apparatus 101. The signal received by antenna 301 is
subjected to predetermined reception processing such as
down-conversion etc. in the RF section 302, and outputted to the
despreading/demodulating section 303.
[0029] Then, the received signal inputted from the RF section 302
is despread and demodulated in the despreading/demodulating section
303, and outputted to the CRC section 304 and the CIR measuring
section 306.
[0030] Then, CIR of the pilot burst signal included in the despread
and demodulated received signal is measured in the CIR. measuring
section 306. The measured. CIR value is outputted to the rate
request value deciding section 307.
[0031] Then, in the rate request value deciding section 307, a rate
corresponding to the measured CIR value is selected from the
previously stored data transmission rates, and outputted to the
rate request value transmission controlling section 308 as the
mobile station's own rate request value.
[0032] On the other hand, CRC check on the received signal which
has been despread and demodulated is performed in the CRC section
304, and, as a result of the CRC check, when no error is detected,
the received signal is outputted to the disassembling section 305.
When error is detected, the received signal is not outputted to the
disassembling section 305.
[0033] Then, in the disassembling section 305, on receiving the
despread and demodulated received signal from the CRC section 304,
the received signal is disassembled to pick out the average rate
signal broadcasted by the base station apparatus 101. The average
rate signal thus obtained is outputted to the rate request value
transmission controlling section 308.
[0034] Then, in the rate request value transmission controlling
section 308, the difference between the own rate request value
decided in the rate request value deciding section 307 and the
average rate signal broadcasted by the base station apparatus 101
is obtained, and only when the obtained difference is larger than
the previously set threshold value (reference value), the rate
request value is outputted to the multiplexing section 309. That is
to say, when the difference between the rate request value and the
average rate is not more than the threshold value, the rate request
value is not outputted to the multiplexing section 309 (that is, it
is not transmitted to the base station apparatus 101).
[0035] Then, the rate request value inputted to the multiplexing
section 309 is multiplexed with its own transmission signal (for
example, a pilot symbol signal for controlling the transmit power,
etc.) in the multiplexing section 309. This multiplexed signal is
modulated and spread in the modulating/spreading section 301,
subjected to the predetermined. transmission processing such as
up-conversion etc., and then transmitted as a radio signal via
antenna 301.
[0036] After that, the base station apparatus 101 receives via
antenna 201 the signal transmitted as a radio signal from the
mobile station apparatus 102. The signal received via antenna 201
is subjected to the predetermined reception processing such as
down-conversion etc. in the RF section 202, and outputted to the
despreading/demodulating section 208.
[0037] Then, the received signal inputted from the RF section 202
is despread and demodulated in the despreading/demodulating section
208, and outputted to the TPC generating section 211 and the radio
resource controlling section 212.
[0038] Then, a TPC signal for controlling transmit power of the
mobile station apparatus 102 is generated according to the pilot
symbol signal included in the despread and demodulated received
signal in the TPC generating section 211. The generated TPC signal
is assembled into a MAC channel in the MAC channel assembling
section 210, modulated and spread in the modulating/spreading
section 206, and outputted to the multiplexing section 203.
[0039] On the other hand, the mobile station apparatus 102 to which
the data is transmitted is selected in the radio resource
controlling section 212 based on the rate request value included in
the received signal that has been despread and demodulated.
Specifically, for example, the rate request values from the
respective mobile station apparatuses 102 are compared, and the
mobile station apparatus 102 that has the largest rate request
value is selected. This selection result is outputted to the
buffering section 216 and the dedicated channel coding section 209.
In addition, the radio resource controlling section 212 outputs a
signal that specifies the modulating mode (for example, QPSK, 16
QAM, 64 QAM, etc.) to the modulating/spreading section 205.
[0040] Furthermore, the criterion of selecting the mobile station
apparatus 102 is not limited to the example described above. For
example, in order to allow every mobile station apparatus 102 to
carry out communication, such selection may be adopted that the
mobile station apparatus 102 which has a small rate request value
is selected. However, in this case, the average data transmission
rate (throughput) of the base station apparatus 101 is
decreased.
[0041] Then, in the buffering section 216, the transmission data
for the selected mobile station apparatus 102 is read out. To the
read out transmission data is given destination information for the
relevant mobile station apparatus 102 in the dedicated channel
coding section 209. The data to which the destination information
is given is modulated in accordance with the specified modulating
mode and spread in the modulating/spreading section 205, and then
outputted to the multiplexing section 203.
[0042] Moreover, the radio resource controlling section 212 outputs
information on the rate that has been used for data transmission to
the selected mobile station apparatus 102 sequentially to the
average rate calculating section 214.
[0043] Then, the average value (average rate) of the rates that
have been used for data transmission to the selected mobile station
apparatus 102 is calculated in the average rate calculating section
214. The average rate signal is assembled as broadcast channel
information in the broadcast channel assembling section 215,
modulated and spread in the modulating/spreading section 207, and
then outputted to the multiplexing section 203.
[0044] The respective signals described above and outputted to the
multiplexing section 203 (TPC signal, transmission data with
destination information, average rate signal and pilot burst
signal) are multiplexed in the multiplexing section 203, subjected
to the predetermined transmission processing such as up-conversion
etc. in the RF section 202, and then transmitted as a radio signal
via antenna 201.
[0045] After that, the mobile station apparatus 102 receives the
signal from the base station apparatus 101, and when its own
destination information is included in that received signal,
receives the succeeding transmission data.
[0046] Therefore, according to the mobile communication system of
this embodiment, since the mobile station apparatus 1102 transmits
the rate request value to the base station 101 only when no error
exists in the received signal and when the difference between the
rate request value and the average rate is larger than a threshold
value, it is not necessary to transmit the rate request value all
the time like the conventional art, and it is possible to increase
in efficiency of transmission timing of the data transmission rate
request value to prevent wasteful power consumption and hence
reduce power consumption in a mobile communication using a shared
channel.
Second Embodiment
[0047] FIG. 4 is a block diagram illustrating a constitution of a
base station apparatus in a mobile communication system according
to a second embodiment of the present invention, FIG. 5 is a block
diagram illustrating a constitution of a mobile station apparatus
in the mobile communication system according to the second
embodiment. The base station apparatus and the mobile station
apparatus of the mobile communication system have the same basic
structure as the base station apparatus and the mobile station
apparatus in the first embodiment shown in FIG. 2 and FIG. 3
respectively, so that the identical component elements are given
with the same reference numeral and their description will be
omitted.
[0048] The base station apparatus 401 shown in FIG. 4 includes, in
addition to the antenna 201, the RF section 202, the multiplexing
section 203, the three modulating/spreading section 204, 205 and
206, the despreading/demodulating section 208, the dedicated
channel coding section 209, the MAC channel assembling section 210,
the TPC generating section 211 and the buffering section 216 as
described above, a radio resource controlling section 402 and a SIR
(Signal to Interference Ratio; the ratio of desired signal power to
interference signal power) measuring section 403 which are
essential elements of this embodiment.
[0049] The mobile station apparatus 501 shown in FIG. 5 includes,
in addition to the antenna 301, the RF section 302, the
despreading/demodulating section 303, the CRC section 304, the CIR
measuring section 306, the rate request value deciding section 307,
the multiplexing section 309 and the modulating/spreading section
310 as described above, a rate request value transmission
controlling section 502 which is an essential element of this
embodiment.
[0050] Next, the operation of the mobile communication system
having the constitution as described above will be described. As
for the parts that are the same as those in the first embodiment,
the description thereof will be omitted or just briefly
described.
[0051] First, the base station apparatus 401 multiplexes the pilot
burst signal that has been modulated and spread with other signals
that have been modulated and spread, and transmits the multiplexed
signals as a radio signal.
[0052] After that, the mobile station apparatus 501, on receiving
the signal transmitted from the base station apparatus 401,
measures CIR of the pilot burst signal in the CIR measuring section
306, decides a rate request value corresponding to the measured CIR
value in the rate request value deciding section 307 and outputs
the decided rate request value to the rate request value
transmission controlling section 502. The rate request value
transmission controlling section 502 has a function of storing the
rate request value.
[0053] Then, the rate request value transmission controlling
section 502, utilizing the function of storing the rate request
value, compares the present rate request value from the rate
request value deciding section 307 with the previous rate request
value, and only when the present rate request value is different
from the previous rate request value, outputs the present rate
request value to the multiplexing section 309. That is to say, when
the present rate request value is the same as the previous rate
request value, the present rate request value is not outputted to
the multiplexing section 309 (that is, it is not transmitted to the
base station apparatus 401).
[0054] Then, the multiplexing section 309 multiplexes, when the
rate request value is inputted from the rate request value
transmission controlling section 502, the input rate request value
with its own transmission signal which includes the pilot symbol
signal for controlling the transmit power, and then transmits the
multiplexed signals as a radio signal. On the contrary, when the
rate request value is not inputted, only the pilot symbol signal
for controlling transmission power is transmitted as a radio
signal.
[0055] After that, the base station apparatus 401 receives the
signal transmitted as a radio signal from the mobile station
apparatus 501, processes the received signal in the despreading
/demodulating section 208, and then outputs the processed received
signal to the TPC generating section 211, the radio resource
controlling section 402 and the SIR measuring section 403.
[0056] Then, when the rate request value is included in the
received, signal, similar to the radio resource controlling section
212 in the first embodiment, the radio resource controlling section
402 selects the mobile station apparatus 102 to which the data is
transmitted based on the rate request value. Specifically, for
example, the rate request values from the respective mobile station
apparatus 102 are compared and the mobile station apparatus 102
that has the largest rate request value is selected. Then, the
transmission data for the selected mobile station apparatus 501 is
read out in the buffering section 216, and to this read out
transmission data is given destination information for the relevant
mobile station apparatus 501 in the dedicated channel coding
section 209.
[0057] On the contrary, when the rate request value is not included
in the received signal, i.e., when the rate request value is not
received but only the pilot symbol signal is received, the radio
resource controlling section 402 inputs the measured SIR value of
the received signal from the SIR measuring section 403, and decides
whether or not the input measured SIR value is equal to or larger
than a preset threshold value (reference value), that is, whether
or not the reception quality is equal to or higher than the preset
quality. As a result, when the measured SIR value is equal to or
larger than the threshold value, the radio resource controlling
section 402 decides that the mobile station apparatus 501 did not
transmit rate request value this time since its value was the same
as the previous rate request value, and, as for the relevant mobile
station apparatus 501, performs the above-mentioned selection
(selection of the mobile station apparatus 501 from which the data
is transmitted) using the rate request value that has been
previously received.
[0058] Therefore, according to the mobile communication system of
this embodiment, since the mobile station apparatus 501 transmits
the latest rate request value to the base station 401 only when the
latest rate request value is different from the previous rate
request value, and the base station apparatus 401 selects the
mobile station apparatus to which the date is transmitted using the
rate request value previously received when the base station
apparatus 401 dose not receive the rate request value this time
from the mobile station apparatus 501 and when the measured SIR
value of the received signal is equal to or larger than the
threshold value, it is not necessary for the mobile station
apparatus to transmit the rate request value all the time like the
conventional art, and it is possible to increase in efficiency of
transmission timing of the data transmission rate request value to
prevent wasteful power consumption and hence reduce power
consumption in a mobile communication using a shared channel.
[0059] Further, since SIR value is used as a reception quality, the
base station apparatus 401 can measure correctly the quality of the
received signal, and perform the above-mentioned selection
correctly.
Third Embodiment
[0060] A third embodiment is the case where the mobile station
apparatus transmits the rate request value to the base station
apparatus 401 even if there is no change in the rate request value,
when such a state has been continued for a predetermined period of
time that the mobile station apparatus does not transmit the latest
rate request value to the base station apparatus 401 since the
latest rate request value is the same as the previous rate request
value in the second embodiment.
[0061] FIG. 6 is a diagram used for illustrating transmission
timing of the rate request value in the mobile station apparatus
501 of the second embodiment, wherein FIG. 6A shows an example of
the rate request value decided by the mobile station apparatus 501,
FIG. 6B shows an example of the rate request value transmitted from
the mobile station apparatus 501, and FIG. 6C shows an example of
the rate request value recognized by the base station apparatus 401
when an error has occurred.
[0062] In the second embodiment, as shown in FIG. 6B, the rate
request value is transmitted only when the rate request value has
changed. At this time, for example, when the rate request value
("4") which corresponds to the frame F1 immediately before the rate
request value becomes not to change is transmitted from the mobile
station apparatus 501 to the base station apparatus 401, and when
the rate request value is erroneously recognized by the base
station apparatus 401 (for example, "4".fwdarw."5") as shown in
FIG. 6C, then consequently the erroneous rate request value is
continuously recognized by the base station apparatus 401 during
the period D1 until the rate request value is transmitted again.
Accordingly, the base station apparatus 401 selects the target to
which the data is transmitted (mobile station apparatus 501) based
on the erroneous rate request value until the rate request value
changes next time, so that there is a possibility that the
above-mentioned selection may not be made correctly during the
period D1 where the rate request value does not change.
[0063] So, in this embodiment, the mobile station apparatus
(hereinafter, the mobile station apparatus in this embodiment is
given with a reference number "501a") transmits the rate request
value to the base station apparatus 401 even if there is no change
in the rate request value, when such a state has been continued for
a predetermined period of time that the mobile station apparatus
does not transmit the rate request value. That is, even when there
is no change in the rate request value, the rate request value is
retransmitted to the base station apparatus 401 at a predetermined
period.
[0064] FIG. 7 is a diagram corresponding to FIG. 6 and used for
illustrating transmission timing of the rate request value in the
mobile station apparatus 501a of this embodiment, wherein FIG. 7A
shows an example of the rate request value decided by the mobile
station apparatus 501a, FIG. 7B shows an example of the rate
request value transmitted by the mobile station apparatus 501a, and
FIG. 7C shows an example of the rate request value recognized by
the base station apparatus 401 when an error has occurred.
[0065] In this embodiment, even in a period when the rate request
value does not change, for example, as shown in FIG. 7B, in the
case where such a state that the rate request value is not
transmitted for four frames successively, the rate request value is
bound to be transmitted at the fifth frame (in the example of FIG.
7, frame F6 and frame F11) even when there is no change in the rate
request value. That is to say, the rate request value is
transmitted at a period of five frames. Accordingly, as shown in
FIG. 7C, even when the rate request value corresponding to the
frame immediately before the rate request value becomes not to
change (in the example of FIG. 7, frame F1) is erroneously
recognized by the base station apparatus 401, the same rate request
value is transmitted from the mobile station apparatus 501a at a
period of five frames, so that the base station apparatus 401 is
able to recognize the correct rate request value and to correct the
error of the rate request value promptly as long as the above rate
request value is received correctly. That is, the time (duration)
when erroneous information is held is reduced from D1 to D2
(D1=D2+D3). Here, the durations D1 and D2 denote durations when the
base station apparatus 401 misrecognizes the rate request value and
the duration D3 denotes a duration when the base station apparatus
recognizes the rate request value correctly.
[0066] Therefore, according to the mobile communication system in
this embodiment, since the mobile station apparatus 501a transmits
(retransmits) the rate request value to the base station apparatus
401 at a predetermined period even if there is no change in the
rate request value, when such a state has been continued for a
predetermined period of time that the mobile station apparatus 501a
does not transmit the rate request value, the period of time when
an erroneous rate request value is held in the base station
apparatus 401 can be reduced, and the base station apparatus 401
can select promptly and correctly the target to which the data is
transmitted.
[0067] Further, although the period of retransmitting the rate
request value is five frames in this embodiment, it is not limited
to this. The period for retransmission of the rate request value is
changeable appropriately depending on the propagation conditions.
For example, when the propagation conditions change drastically, by
reducing the period of retransmission, and when the propagation
conditions do not change so drastically, by elongating the period
of retransmission, respectively, the power consumption of the
mobile station apparatus 501a can be reduced and the
above-mentioned selection in the base station apparatus 401 can be
carried out more correctly.
[0068] Furthermore, although the present invention is applicable,
particularly to the shared channel used in HDR which is applied to
CDMA2000, it is not limited to this, for example, the same is also
applicable to a desired adaptive modulation system in which a base
station apparatus transmits data at a data transmission rate
requested by a mobile station apparatus.
[0069] This application is based on the Japanese Patent Application
No. 2000-232268 filed on Jun. 26, 2000, and the Japanese Patent
Application No. 2000-204222 filed on Jul. 5, 2000, entire content
of which is expressly incorporated by reference herein.
INDUSTRIAL APPLICABILITY
[0070] The invention is applicable to a mobile communication
system, and a base station apparatus and a mobile station apparatus
constituting the same.
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