U.S. patent application number 10/899061 was filed with the patent office on 2004-12-30 for method for controlling transmit power in a communication system.
Invention is credited to Suzuki, Toshinori, Suzuki, Toshiro, Tsunehara, Katsuhiko, Uta, Takaki, Yano, Takashi.
Application Number | 20040266473 10/899061 |
Document ID | / |
Family ID | 18477947 |
Filed Date | 2004-12-30 |
United States Patent
Application |
20040266473 |
Kind Code |
A1 |
Tsunehara, Katsuhiko ; et
al. |
December 30, 2004 |
Method for controlling transmit power in a communication system
Abstract
The present invention provides a transmit power controlling
method for reducing an influence of incorrect control in a mobile
communication system in the CDMA mode. A likelihood of transmit
power controlling signal is generated on the basis of the transmit
power controlling signal transmitted by a radio base station and
the receiving quality, a variation amount of the transmit power is
generated on the basis of the likelihood, and the transmit power of
a mobile station is controlled on the basis of the variation
amount.
Inventors: |
Tsunehara, Katsuhiko;
(Kokubunji, JP) ; Yano, Takashi; (Kokubunji,
JP) ; Uta, Takaki; (Kokubunji, JP) ; Suzuki,
Toshiro; (Yokohama, JP) ; Suzuki, Toshinori;
(Tokyo, JP) |
Correspondence
Address: |
ANTONELLI, TERRY, STOUT & KRAUS, LLP
1300 NORTH SEVENTEENTH STREET
SUITE 1800
ARLINGTON
VA
22209-9889
US
|
Family ID: |
18477947 |
Appl. No.: |
10/899061 |
Filed: |
July 27, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10899061 |
Jul 27, 2004 |
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09786459 |
Sep 10, 2001 |
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09786459 |
Sep 10, 2001 |
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PCT/JP99/07174 |
Dec 21, 1999 |
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Current U.S.
Class: |
455/522 ;
455/135; 455/69 |
Current CPC
Class: |
H04W 52/146 20130101;
H04W 52/16 20130101; H04W 52/367 20130101; H04W 52/248 20130101;
H04W 52/10 20130101; H04W 52/246 20130101; H04W 52/08 20130101;
H04W 52/241 20130101 |
Class at
Publication: |
455/522 ;
455/069; 455/135 |
International
Class: |
H04Q 007/20; H04B
001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 21, 1998 |
JP |
10-362871 |
Claims
What is claimed is:
1. A transmit power controlling method in a code division multiple
access communication system comprising a radio base station and a
mobile station, characterized in that said radio base station
measures SIR for every said mobile station to compare each of said
measured SIRs with a target SIR given in advance, generates a
transmit power controlling signal for decreasing the transmit power
when said SIR is the target SIR or more or when said radio base
station has stopped a receiving operation for said mobile station,
generates a transmit power controlling signal for increasing the
transmit power when said SIR is less than the target SIR, and
transmits said generated transmit power controlling signal to the
mobile station.
2. A radio base station controlling transmit power of a mobile
station characterized by comprising: signal quality measuring means
for measuring signal quality of said mobile station; comparing
means for comparing the signal quality measured by said signal
quality measuring means with a predetermined value; generating
means for generating, as a result of comparison in said comparing
means, transmit power controlling information for decreasing said
transmit power when said signal quality is said predetermined value
or more and for generating transmit power controlling information
for increasing said transmit power when said signal quality is less
than said predetermined value; and transmitting means for
transmitting to said mobile station the transmit power controlling
signal generated by said generating means.
3. The radio base station according to claim 2, characterized in
that said signal quality is SIR.
4. A radio base station controlling transmit power of a mobile
station characterized by comprising: receiving means for receiving
a channel transmitted by said mobile station; controlling means for
controlling a receiving operation of said receiving means;
generating means for generating instructing information for giving
an instruction to decrease the transmit power of said mobile
station at the time when said controlling means stops the receiving
operation of said receiving means; and transmitting means for
transmitting to said mobile station the instructing information
generated by said generating means.
5. A radio base station controlling transmit power of a mobile
station characterized by comprising: receiving means for receiving
a channel transmitted by said mobile station; controlling means for
controlling a receiving operation of said receiving means;
generating means for generating instructing information for giving
an instruction to decrease the transmit power of said mobile
station when said controlling means tries to stop the receiving
operation of said receiving means; and transmitting means for
transmitting to said mobile station the instructing information
generated by said generating means before said receiving operation
is stopped.
Description
[0001] The present application is a divisional application of
application Ser. No. 09/786,459, filed Sep. 10, 2001, the contents
of which are incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to a method for controlling
transmit power in a mobile communication system, more particularly,
a method for controlling transmit power in a mobile communication
system to which a code division multiple access (CDMA) mode is
applied.
BACKGROUND OF THE INVENTION
[0003] In the CDMA mode, a plurality of mobile stations share a
same frequency band to communicate with a base station. Therefore,
in the case of a communication between a mobile station A and a
base station, for example, a signal from another mobile station B
to the base station (an undesired signal) interferes a signal sent
from the mobile station A to the base station (a desired signal) to
obstruct a communication between the mobile station A and the base
station. Similarly, the signal sent from the mobile station A
obstructs a communication between the mobile station B and the base
station.
[0004] The interference level increases relative to a receiving
level of an undesired signal wave received by the base station. The
receiving level of the undesired signal is relative to the transmit
power at the time the undesired signal is sent from a mobile
station. Thus, it is necessary for the base station to control the
transmit power from mobile stations so that the receiving level in
the base station should be always minimum essential, in order to
keep the interference level minimum. Under an ideal situation of
this control, the number of channels available for communication
becomes the largest, while the number of channels available for a
communication would decrease as the situation goes away from the
ideal.
[0005] Concerning a technology in controlling transmit power in a
CDMA mobile communication, provided a transmit power controlling
method described in IMT-2000 Study Committee, Air-interface WG, SWG
Document Title: Volume 3 Specifications of Air-Interface for 3G
Mobile System, Source: SWG, Version: 0-4.0, Date: Dec. 18, 1997
issued by DENPA SANGYOUKAI, for example (referred to as "W-CDMA
mode", hereinafter). A transmit power controlling method in the
W-CDMA mode will be described below. In the description, an
upstream direction means a direction of sending signals from a
mobile station to a base station and a downstream direction means a
direction of sending signals from a base station to a mobile
station.
[0006] A base station measures a signal to interference power ratio
(SIR) of a signal sent from a mobile station in the upstream
direction to transmit a transmit power controlling signal in
accordance with the measured SIR. A structural diagram of a
conventional base station is shown in FIG. 29. A signal received by
an antenna 210 passes through a circulator 211 to take a process of
modulating a base band signal and a process of receiving at a
high/middle frequency in a radio module for receiving 212. The base
station carries out processes of synchronous capturing and reverse
spreading of the received signal in synchronous capturing/reverse
spreading circuits 213a to 213n in which a parameter is set for
each mobile station, since the received signal is a multiplex
signal from a plurality of mobile stations (referred to as MSa to
MSn). The signal output from the capturing/reverse spreading
circuits 213a to 213n is input to detecting potions 214a to 214n,
respectively, to take a detecting process such as compensation for
a phase rotation. The signal output from the detecting portions
214a to 214n is input to demodulating portions 215a to 215n,
respectively, to take an error controlling process such as
de-interleave and Viterbi decoding, and then, are used as received
data.
[0007] On the other hand, the signal output from the
capturing/reverse spreading circuits 213a to 213n is input to an
upstream channel SIR measuring portion 221 through signal lines
220a to 220n, respectively. The upstream channel SIR measuring
portion 221 measures SIR of the received signal input through the
signal lines 220a to 220n, respectively (referred to as SIRa to
SIRn), to input the SIRa to SIRn to an upstream channel transmit
power controlling signal generating portion 222 through the signal
lines 230a to 230n.
[0008] The upstream channel transmit power controlling signal
generating portion 222 compares SIRa to SIRn with target SIRs given
for MSa to MSn in advance by a controlling portion 500 (referred to
as T-SIRa to T-SIRn) to generate transmit power controlling signals
(TPCa to TPCn) for MSa to MSn. The controlling portion 500 is an
element that controls a whole base station and that transmits
various signals to each element in the base station. In FIG. 29,
signal lines are omitted other than the line to the upstream
channel transmit power controlling signal generating portion 222 in
order to simplify the diagram. A structure of the controlling
portion/the upstream channel transmit power controlling signal
generating portion 222 is shown in FIG. 30. The upstream channel
transmit power controlling signal generating portion 222 comprises
transmit power controlling signal generating portions 222a to 222n
whose inputs are SIRi and T-SIRi and whose outputs are TPCi. The
added character "i" denotes one of characters "a" to "n". A
structure of a transmit power controlling signal generating portion
222i is shown in FIG. 31. A comparator 223i compares SIRi and
T-SIRi input through a signal line 230i to generate a signal that
selects 0 in a selector 224i in the case of SIRi.gtoreq.T-SIRi, and
a signal that selects 1 in the selector 224i in the case of
SIRi<T-SIRi. The selector 224i selects either 0 or 1 in
accordance with an output from the comparator 223i to output it as
TPCi through a signal line 231i. The TPCi=0 is a signal that
instructs a mobile station to reduce the transmit power. On the
contrary, TPCi=1 is a signal that instructs a mobile station to
increase the transmit power.
[0009] Frame forming portions 225a to 225n shown in FIG. 29 form
transmission data to MSa to Msn, the data which took an error
controlling process such as fold-encoding and interleave in
encoding portions 222a to 222n, and the transmit power controlling
signals TPCa to TPCn, which are input from the upstream channel
transmit power controlling signal generating portion 222, into
frames in accordance with a format defined in the system. Spreading
circuits 223a to 223n carry out a spectrum spreading process for
outputs from the frame forming portions with a parameter
corresponding to MSa to MSn. An adding circuit 226 adds
transmission signals in order to multiplex signals for MSa to MSn.
The transmission signals output from the adding circuit 226 are
transmitted from the antenna 210 after passing through a radio
module for transmission 224 and a circulator 211.
[0010] A mobile station MSi receives the aforementioned transmit
power controlling signal TPCi to change the transmit power in
accordance with a result of demodulation. A structure of a
conventional mobile station is shown in FIG. 32. A signal received
by the antenna 10 passes through a circulator 11 to take a process
of demodulating a base band signal and a process of receiving at a
high/middle frequency in a radio module for receiving 12.
[0011] A mobile station carries out processes of synchronous
capturing and spectrum reverse spreading of the received signal in
a synchronous capturing/reverse spreading circuit 13 in which a
parameter is set for a channel being used in the mobile station,
since the received signal is a multiplex signal in a plurality of
channels. The signal output from the synchronous capturing/reverse
spreading circuit 13 takes a detecting process such as compensation
for a phase rotation in a detecting portion 14 and takes an error
controlling process such as de-interleave and Viterbi decoding in
demodulating portion 15, so as to be used as received data.
[0012] After output from the detecting portion 14, the received
transmit power controlling signal passes through a signal line 16
and is input to a transmit power controlling signal determining
portion 40. The transmit power controlling signal determining
portion 40 determines whether the received transmit power
controlling signal is "0" or "1". The transmit power controlling
signal determining portion 40 generates a controlling signal, which
selects "-1 dB", for example, as an output for a selector 41 when
the result of determining the transmit power controlling signal is
"0", and generates a controlling signal, which selects "+1 dB", for
example, as an output for the selector 41 when the result of
determining is "1", to send the controlling signal to the selector
41.
[0013] The selector 41 outputs either "+1 dB" or "-1 dB", for
example, as a variation amount of the transmit power in accordance
with a controlling signal input from the transmit power controlling
signal determining portion 40.
[0014] A transmit power calculating portion 19 determines the
changed transmit power, using the variation amount of the transmit
power input from the selector 41 and the current transmit power
input from a transmit power maintaining circuit 20. That is, the
changed transmit power is increased by 1 dB from the current
transmit power when the selector inputs "+1 dB", and it is
decreased by 1 dB from the current transmit power when the selector
contrary inputs "-1 dB".
[0015] The transmission signal takes an error controlling process
such as, for example, fold-encoding and interleave, in the encoding
portion 22 to form a frame of a format defined in the system in a
frame forming portion 25, and then, takes a spectrum spreading
process in a spreading circuit 23. A variable gain amplifier 21
amplifies transmission signals at a proper gain so that the signals
could be transmitted at the designated transmit power from the
transmit power calculating portion 19. The transmission signal
output from the variable gain amplifier 21 passes through the radio
module for transmission 24 and the circulator 11, and then, is
transmitted from the antenna 10.
[0016] An example of a change of the transmit power of a mobile
station in the case that the mobile station performs the above
operation is shown as a solid line 62 in FIG. 33. The horizontal
axis 60 shows the time, while the vertical axis 61 shows the
transmit power of the mobile station. Results 83a to 83e of
determining the transmit power controlling signal received at the
times 120 to 124 are also shown in the horizontal axis 60. As shown
in FIG. 33, the mobile station operates so as to increase the
transmit power by 1 dB at the times 122 and 124 when the result of
determining the controlling signal is "1" and so as to decrease the
transmit power by 1 dB at the times 120, 121 and 123 when the
result of determining the controlling signal is "0".
[0017] There are two problems solved by the invention as described
below.
[0018] First, there is a large possibility that the received
transmit power controlling signal would result in being demodulated
with an error, when the quality of receiving the transmit power
controlling signal in a mobile station is bad. In this case, the
conventional method that the demodulated result is determined
either "0" or "1" increases the possibility that the transmit power
controlling signal is incorrectly determined to be a value
different from the proper value.
[0019] In the case that the transmit power controlling signal,
which should be determined to be "1", is incorrectly determined to
be "0", namely, in the case that a mobile station incorrectly
decreases the transmit power at the time when the transmit power
should be increased, the quality of a signal received from the
above mobile station would deteriorate in the base station. This
causes the quality of a communication to be deteriorated, and
furthermore, causes a communication to be cut off.
[0020] To the contrary, in the case that the transmit power
controlling signal, which should be determined to be "0", is
incorrectly determined to be "1", namely, in the case that a mobile
station incorrectly increases the transmit power at the time when
the transmit power should be decreased, the interference amount by
the above mobile station to another mobile station would increase
in the base station. Therefore, deterioration of the communication
quality and cut-off of a communication occur in the other mobile
station. This means, at the same time, that the number of mobile
stations available for a communication would decrease, and as a
result, the communication capacity of the whole system will be
reduced.
[0021] Moreover, the aforementioned deterioration of the
communication quality and reduction of the communication capacity
of the system appear more significantly, when the result of
determining the transmit power controlling signal, whose receiving
quality is bad, is biased to either "0" or "1" due to such as a
component of direct current offset contained in a receiver in a
mobile station.
[0022] Secondly, when a receiving operation stops earlier than a
transmitting operation as a controlling sequence in the base
station upon cutting off a communication, that is, an operation of
the synchronous capturing/reverse spreading circuit 213i (i=1, 2, .
. . , n) stops earlier than that of the upstream channel SIR
measuring portion 221 in FIG. 29, it is considered that the
operation of the upstream channel SIR measuring portion 221 would
become unstable, since the upstream channel SIR measuring portion
221 tries to get SIRi from the output of the synchronous
capturing/reverse spreading circuit 213i whose operation has
stopped. In this case, an improper transmit power controlling
signal TPCi is generated to be transmitted from the base station to
the mobile station MSi. The mobile station MSi may perform
transmission with an excessive transmit power, as a result of
controlling the transmit power in accordance with the
above-mentioned improper transmit power controlling signal TPCi. In
this case, the interference amount by a signal of the mobile
station MSi to another mobile station increases in the base
station. Thus, the deterioration of the communication quality and
cut-off of a communication occur in the other mobile station. This
reduces the communication capacity of the whole system, like the
first problem.
SUMMARY OF THE INVENTION
[0023] In order to solve the first problem, a structure according
to the present invention is arranged so that a radio base station
transmits a transmit power controlling signal for controlling
transmit power of a mobile station, and that said mobile station
calculates a likelihood of said transmit power controlling signal
on the basis of the received transmit power controlling signal and
the receiving quality to calculate a variation amount of the
transmit power on the basis of said likelihood, so that the
transmit power of the mobile station would be controlled on the
basis of the variation amount.
[0024] Further, in order to solve the first problem, the invention
is characterized in that said likelihood is calculated by further
adding a perch receiving quality of a signal transmitted by said
radio base station; that the perch receiving quality of a signal
transmitted by said radio base station is compared with the
receiving quality of a transmit power controlling signal so that it
is determined that a call is cut off in a channel being received
when only the receiving quality of the channel being received is
deteriorated and it is determined that a receiving condition is no
longer proper due to a mobile station being in shade or the like
when the both of the receiving qualities are deteriorated at the
same time; and that the likelihood is calculated on the basis of a
result of the determination.
[0025] In order to solve the first problem, the invention is also
characterized in that, when an absolute value of the likelihood of
said transmit power controlling signal is large, an upper limit
value and a lower limit value of the transmit power of a mobile
station are updated and maintained so that the transmit power of
said mobile station is limited between said upper limit value and
said lower limit value.
[0026] In order to solve the first problem, the invention is also
characterized in that an average value of the transmit power of a
mobile station is calculated, and that the transmit power of said
mobile station is switched on the basis of the size of said
likelihood so as to be said calculated average transmit power of
the mobile station or transmit power of the mobile station that is
calculated on the basis of said likelihood.
[0027] In order to solve the first problem, the invention is
characterized in that open loop transmit power is calculated on the
basis of the receiving quality or the receiving power of another
channel different from a channel being used, and that the transmit
power of said mobile station is switched on the basis of the size
of said likelihood so as to be said calculated open loop transmit
power or transmit power of the mobile station that is calculated on
the basis of said likelihood.
[0028] In order to solve the first problem, the invention is
characterized in that said transmit power controlling signal is a
signal comprising two values, and that said likelihood is
calculated so that an absolute value of the likelihood would be
large when the receiving quality is good and so that an absolute
value of the likelihood would be small when the receiving quality
is bad.
[0029] In order to solve the first problem, the invention is
characterized in that the transmit power is increased when said
likelihood is a first reference value or more, that the transmit
power is maintained when said likelihood is less than said first
reference value and the second reference value or more, and that
the transmit power is decreased when said likelihood is less than
said second reference value.
[0030] In order to solve the first problem, the invention is
characterized in that the transmit power is increased when said
likelihood is said first reference value or more, that the transmit
power is toggle-controlled when said likelihood is less than said
first reference value and said second reference value or more, and
that the transmit power is decreased when said likelihood is less
than said second reference value.
[0031] In order to solve the first problem, the invention is
characterized in that the transmit power is increased when said
likelihood is said first reference value or more, that a variation
amount of the transmit power is made to be the power corresponding
to said likelihood when said likelihood is less than said first
reference value and said second reference value or more, and that
the transmit power is decreased when said likelihood is less than
said second reference value.
[0032] In order to solve the first problem, a mobile station
according to the invention comprises: receiving means for receiving
transmit power controlling information transmitted by a radio base
station; measuring means for measuring the receiving quality of a
wave transmitted by said radio base station; likelihood generating
means for generating a likelihood of said transmit power
controlling information on the basis of the transmit power
controlling information received by said receiving means and the
receiving quality measured by said measuring means; variation
amount generating means for generating a variation amount of the
transmit power on the basis of the likelihood generated by said
likelihood generating means; and controlling means for controlling
the transmit power of a mobile station on the basis of the
variation amount generated by said variation amount generating
means.
[0033] In order to solve the first problem, a mobile station
according to the invention further comprises perch receiving
quality measuring means for measuring the receiving quality of a
perch signal transmitted by said radio base station, wherein said
likelihood generating means generates a likelihood with the
receiving quality measured by said perch receiving quality
measuring means taken into a consideration.
[0034] In order to solve the first problem, in a communication
system according to the invention, a radio base station comprises:
transmit power controlling information generating means for
generating transmit power controlling information for controlling
the transmit power of a mobile station; and transmitting means for
transmitting the transmit power controlling information generated
by said transmit power controlling information generating means,
and a mobile station comprises: receiving means for receiving the
transmit power controlling information transmitted by said transmit
means; measuring means for measuring the receiving quality of a
wave transmitted by said radio base station; likelihood generating
means for generating a likelihood of said transmit power
controlling information on the basis of the transmit power
controlling information received by said receiving means and the
receiving quality measured by said measuring means; variation
amount generating means for generating a variation amount of the
transmit power on the basis of the likelihood generated by said
likelihood generating means; and controlling means for controlling
the transmit power of a mobile station on the basis of the
variation amount generated by said variation amount generating
means.
[0035] In order to solve the second problem, the invention is
characterized in that a radio base station measures SIR for every
said mobile station to compare each of said measured SIRs with a
target SIR given in advance, generates a transmit power controlling
signal for decreasing the transmit power when said SIR is the
target SIR or more or when said radio base station has stopped a
receiving operation for said mobile station, generates a transmit
power controlling signal for increasing the transmit power when
said SIR is less than the target SIR, and transmits said generated
transmit power controlling signal to the mobile station.
[0036] In order to solve the second problem, the invention is
characterized by a radio base station controlling transmit power of
a mobile station comprising: signal quality measuring means for
measuring signal quality of said mobile station; comparing means
for comparing the signal quality measured by said signal quality
measuring means with a predetermined value; generating means for
generating, as a result of comparison in said comparing means,
transmit power controlling information for decreasing said transmit
power when said signal quality is said predetermined value or more
and for generating transmit power controlling information for
increasing said transmit power when said signal quality is less
than said predetermined value; and transmitting means for
transmitting to said mobile station the transmit power controlling
signal generated by said generating means. The above signal quality
is SIR or the like.
[0037] In order to solve the second problem, according to the
invention, a radio base station controlling transmit power of a
mobile station comprises: receiving means for receiving a channel
transmitted by said mobile station; controlling means for
controlling a receiving operation of said receiving means;
generating means for generating instructing information for giving
an instruction to decrease the transmit power of said mobile
station at the time when said controlling means stops the receiving
operation of said receiving means; and transmitting means for
transmitting to said mobile station the instructing information
generated by said generating means.
[0038] In order to solve the second problem, according to the
invention, a radio base station controlling transmit power of a
mobile station comprises: receiving means for receiving a channel
transmitted by said mobile station; controlling means for
controlling a receiving operation of said receiving means;
generating means for generating instructing information for giving
an instruction to decrease the transmit power of said mobile
station when said controlling means tries to stop the receiving
operation of said receiving means; and transmitting means for
transmitting to said mobile station the instructing information
generated by said generating means before said receiving operation
is stopped.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] FIG. 1 shows a structure of a mobile station according to
the invention.
[0040] FIG. 2 shows a structure of a transmit power controlling
signal likelihood calculating portion according to the
invention.
[0041] FIG. 3 shows a likelihood calculating method according to
the invention.
[0042] FIG. 4 shows a structure of a transmit power variation
amount calculating portion according to the invention.
[0043] FIG. 5 shows an example of an operation of a likelihood
determining portion according to the invention.
[0044] FIG. 6 shows an example of a change of transmit power of a
mobile station according to the invention.
[0045] FIG. 7 shows a structure of a transmit power variation
amount calculating portion according to the invention.
[0046] FIG. 8 illustrates an operation of a toggle portion
according to the invention.
[0047] FIG. 9 illustrates an operation of a likelihood determining
portion according to the invention.
[0048] FIG. 10 shows an example of a change of transmit power of a
mobile station according to the invention.
[0049] FIG. 11 shows a structure of a transmit power variation
amount calculating portion according to the invention.
[0050] FIG. 12 illustrates an operation of a transmit power
variation amount calculating portion according to the
invention.
[0051] FIG. 13 shows an example of a change of transmit power of a
mobile station according to the invention.
[0052] FIG. 14 shows a structure of a mobile station according to
the invention.
[0053] FIG. 15 shows a structure of a transmit power variation
amount calculating portion according to the invention.
[0054] FIG. 16 illustrates an operation of a likelihood determining
portion according to the invention.
[0055] FIG. 17 shows a structure of a transmit power controlling
portion according to the invention.
[0056] FIG. 18 shows a structure of a transmit power limit value
calculating portion according to the invention.
[0057] FIG. 19 shows an example of a change of transmit power
according to the invention.
[0058] FIG. 20 shows a structure of a mobile station according to
the invention.
[0059] FIG. 21 shows a structure of a transmit power selecting
portion according to the invention.
[0060] FIG. 22 illustrates an operation of a likelihood determining
portion according to the invention.
[0061] FIG. 23 shows a structure of a transmit power selecting
portion according to the invention.
[0062] FIG. 24 shows a structure of a likelihood selecting portion
according to the invention.
[0063] FIG. 25 shows a structure of a base station according to the
invention.
[0064] FIG. 26 shows a structure of an upstream channel transmit
power controlling signal generating portion according to the
invention.
[0065] FIG. 27 shows a structure of the transmit power controlling
signal generating portion according to the invention.
[0066] FIG. 28 illustrates an operation of a selector 235i
according to the invention.
[0067] FIG. 29 shows a structure of a conventional base
station.
[0068] FIG. 30 shows a structure of an upstream channel transmit
power controlling signal generating portion according to the
invention.
[0069] FIG. 31 shows a structure of a conventional transmit power
controlling signal generating portion.
[0070] FIG. 32 shows a structure of a conventional mobile
station.
[0071] FIG. 33 shows a conventional varying state of transmit
power.
[0072] FIG. 34 shows a structure of a receiving quality calculating
portion using perch receiving quality.
[0073] FIG. 35 shows a communication system to which the present
invention is applied.
BEST MODE FOR CARRYING OUT THE INVENTION
[0074] FIG. 35 shows a communication system according to the
present invention. The communication system according to the
invention includes a base station 3500 and mobile stations 3501 to
3503. The mobile station 3501 is located close to the base station
3500 with its line state stable, so that an error of power
controlling bit would be few and power controlling would not be out
of control. The mobile station 3502, however, has an obstacle 3504
such as a building on the way to the base station 3500, although it
is located close to the base station. Therefore, the obstacle 3504
greatly attenuates the wave from the base station 3500, which may
cause an error of the power controlling bit and the power control
to be out of control. Further, the mobile station 3503 is located
far away from the base station 3500, so that attenuation or
interference of the wave may cause an error of the power
controlling bit and the power control to be out of control. The
invention provides a much more stable communication system, in
which the power control itself would not be out of control even
when a mobile station is in a condition that an error of the power
controlling bit easily occurs.
[0075] FIG. 1 shows a structure of a mobile station of a first
embodiment. Elements corresponding to those of a conventional
mobile station shown in FIG. 32 are marked with the same reference
number.
[0076] A received signal is processed in an antenna 10, a
circulator 11, a radio module for receiving 12, a synchronous
capturing/reverse spreading circuit 13 and a detecting portion 14,
respectively, before being input to a transmit power controlling
signal likelihood calculating portion 30 via a signal line 16.
[0077] The transmit power controlling signal likelihood calculating
portion 30 calculates likelihood of a transmit power controlling
signal on the basis of the receiving quality of the received
transmit power controlling signal and a determined result of "0" or
"1". A structure of the transmit power controlling signal
likelihood calculating portion 30 is shown in FIG. 2. A transmit
power controlling signal 0/1 determining portion 40 determines
whether the received transmit power controlling signal is "0" or
"1".
[0078] A receiving quality calculating portion 50 calculates the
receiving quality of the received transmit power controlling signal
to output it to a likelihood calculating portion 51. Basically, the
receiving power, SIR, or the like, which is measured on the instant
upon receiving the transmit power controlling signal, should be
used as receiving quality calculated by the receiving quality
calculating portion 50. On the other hand, a long time integral
operation is required to accurately observe the receiving power or
the SIR. In the case that the above-mentioned receiving power or
the SIR integrated for a long time (referred to as a long time
integral value, hereinafter) is used for transmit power
controlling, which is required to be performed at high speed, it is
considered that the controlling delay would be increased, so that
the transmit power cannot properly controlled. Therefore, the
receiving quality calculating portion 50 calculates the receiving
quality of the transmit power controlling signal, using the above
transmit power controlling signal and the result of integrating the
receiving power or the SIR of a signal received at the time close
to receiving the above transmit power controlling signal (referred
to as a short time integral value, hereinafter).
[0079] Using the short time integral value may cause an incorrect
calculation of the receiving quality when the short time integral
value is used for calculating the receiving quality as it is, since
an error of the short time integral value is considered to be
large. Therefore, the receiving power calculating portion 50 may
compare the long time integral value with the short time integral
value, for example, so as to output the bad receiving quality when
the difference of the both values is large.
[0080] The receiving quality calculating portion 50 also may
perform the following operation in order to estimate that a
receiving condition of a channel being received is no longer proper
due to cutting off a call or being in shade. A mobile station
measures the receiving power or SIR of a channel, which is always
transmitted from the base station like a perch channel in the
W-CDMA mode, for example, and whose transmit power is known
(referred to as perch receiving quality, hereinafter). A structure
of the receiving quality calculating portion in this case is shown
in FIG. 34. A perch receiving quality measuring portion 300
measures the above perch receiving quality. A comparing portion 301
compares the above-mentioned short time integral value and the
perch receiving quality obtained by the perch receiving quality
measuring portion 300. A receiving quality determining portion 302
determines, in accordance with a comparing result at the comparing
portion 301, that a call has been cut off in the channel being
received when only the receiving quality of the channel being
received is deteriorated, and that the receiving condition is no
longer proper due to such a situation that a mobile station is in
shade when the both is deteriorated at the same time, and then,
outputs a bad receiving quality.
[0081] The likelihood calculating portion 51 calculates the
likelihood of the above transmit power controlling signal on the
basis of the result of determining in the transmit power
controlling signal 0/1 determining portion 40 and the result of
calculating in the receiving quality calculating portion 50. An
example of a relation between the likelihood and the results of
determining in the transmit power controlling signal 0/1
determining portion 40 and of calculating in the receiving quality
calculating portion 50 is shown by a bent line 150 in FIG. 3. The
result of calculating the likelihood shown in FIG. 3 will be
described below. It is defined that the likelihood is a positive
value when the result of determining the transmit power controlling
signal is 1. On the other hand, it is defined that the likelihood
is a negative value when the result of determining is 0. Further,
it is defined that an absolute value of the likelihood is large
when the receiving quality is good, while the absolute value of the
likelihood is small when the receiving quality is bad.
[0082] The likelihood of the transmit power controlling signal
calculated in the above method is input to a transmit power
variation amount calculating portion 31 in FIG. 1. The transmit
power variation amount calculating portion 31 calculates the
variation amount of the transmit power on the basis of the
likelihood of the input transmit power controlling signal. A
structure of the transmit power variation amount calculating
portion 31 in the first embodiment is shown in FIG. 4. A likelihood
determining portion 70 generates a controlling signal for selecting
either "+1 dB (increase)", "-1 dB (decrease)" or "0 dB (no
change)", for example, as the variation amount of the transmit
power on the basis of the likelihood of the transmit power
controlling signal input from the transmit power controlling signal
likelihood calculating portion 30 to output the generated signal to
a selector 71. An example of an operation of the likelihood
determining portion 70 in the first embodiment is shown in FIG. 5.
The likelihood determining portion 70 outputs to the selector 71 a
controlling signal such that "+1 dB" is selected in the selector
71, when the likelihood of the transmit power controlling signal to
be input exists within an area 100, which is .alpha.+ or more.
Similarly, the likelihood determining portion 70 outputs to the
selector 71 a controlling signal such that "0 dB" is selected, when
the likelihood of the transmit power controlling signal to be input
exists within an area 101, which is .alpha.- or more and less than
.alpha.+, and the likelihood determining portion 70 outputs a
controlling signal such that "-1 dB" is selected, when the
likelihood of the transmit power controlling signal to be input
exists within an area 102, which is less than .alpha.-. The
selector 71 selects the transmit power variation amount in
accordance with the controlling signal from the likelihood
determining portion 70 to output the variation amount to the
transmit power calculating portion 19 shown in FIG. 1.
[0083] The transmit power calculating portion 19 shown in FIG. 1
calculates the transmit power, as same as the case of the
conventional mobile station, on the basis of the variation amount
of the transmit power input from the transmit power variation
amount calculating portion 31 and of the current transmit power
input from the transmit power maintaining circuit 20. The
transmission signal processed in the encoding portion 22 and the
spreading circuit 23 is amplified so as to be transmitted at the
aforementioned transmit power in the variable gain amplifier 21,
and then, passes through the radio module for transmission 24 and
the circulator 11 to be transmitted from the antenna 10.
[0084] An example of a change of transmit power of a mobile station
in the case that the mobile station performs an operation in the
first embodiment is shown as a solid line 63 in FIG. 6. As shown in
FIG. 6, the mobile station operates so that the variation amount of
the transmit power would be 0 dB, that is, the transmit power would
not be changed, for a time 103 in which the likelihood of the
transmit power controlling signal is .alpha.- or more and less than
.alpha.+.
[0085] Next, an operation of a mobile station of the second
embodiment will be described. A structure of the mobile station in
the second embodiment is shown in FIG. 1 as same as that in the
first embodiment. In the second embodiment, a structure of the
transmit power variation amount calculating portion 31 is different
from that of the first embodiment. The structure of the transmit
power variation amount calculating portion 31 in the second
embodiment is shown in FIG. 7. Elements corresponding to those of
the transmit power variation amount calculating portion 31 in the
first embodiment are marked with the same reference number.
[0086] The likelihood determining portion 70 generates a
controlling signal for selecting either "+1 dB (increase)", "-1 dB
(decrease)" or "toggle portion 72 (toggle operation)", for example,
as a variation amount of the transmit power on the basis of the
likelihood of the transmit power controlling signal input from the
transmit power controlling signal likelihood calculating portion 30
to output the generated signal to the selector 71. An operation of
the toggle portion 72 is shown in FIG. 8.
[0087] The toggle portion 72 outputs "-1 dB" in the case of the
input of "+1 dB", and "+1 dB" in the case of the input of "-1 dB".
An example of an operation of the likelihood determining portion 70
in the second embodiment is shown in FIG. 9. The likelihood
determining portion 70 outputs to the selector 71 a controlling
signal such that "+1 dB" is selected in the selector 71, when the
likelihood of the transmit power controlling signal to be input
exists within an area 100, which is .alpha.+ or more. Similarly,
the likelihood determining portion 70 outputs to the selector 71 a
controlling signal such that "toggle portion 72" is selected, when
the likelihood of the transmit power controlling signal to be input
exists within an area 101, which is .alpha.- or more and less than
.alpha.+, and the likelihood determining portion 70 outputs a
controlling signal such that "-1 dB" is selected, when the
likelihood of the transmit power controlling signal to be input
exists within an area 102, which is less than .alpha.-.
[0088] The selector 71 selects the transmit power variation amount
in accordance with the controlling signal from the likelihood
determining portion 70 to output the variation amount to the
transmit power calculating portion 19 shown in FIG. 1. The
operation thereafter to the transmission of the transmission signal
from the antenna 10 is same as that of the first embodiment.
[0089] An example of a change of transmit power of a mobile station
in the case that a mobile station performs an operation in the
second embodiment is shown as a solid line 64 in FIG. 10. As shown
in FIG. 10, the mobile station operates so that the variation
amount of the transmit power would repeat "+1 dB" and "-1 dB"
alternately, during a time 103 in which the likelihood of the
transmit power controlling signal is .alpha.- or more and less than
.alpha.+.
[0090] Next, an operation of a mobile station of the third
embodiment will be described. A structure of the mobile station in
the third embodiment is shown in FIG. 1 as same as the first and
second embodiments. In the third embodiment, a structure of the
transmit power variation amount calculating portion 31 is different
from that of the first and second embodiments. The structure of the
transmit power variation amount calculating portion 31 in the third
embodiment is shown in FIG. 11. A likelihood-transmit power
variation amount converting portion 73 converts the likelihood of
the transmit power controlling signal input from the transmit power
controlling signal likelihood calculating portion 30 into the
transmit power variation amount. An example of an operation of the
likelihood-transmit power variation amount converting portion 73 is
shown as a line 74 in FIG. 12. In FIG. 12, the likelihood-transmit
power variation amount converting portion 73 outputs "+1 dB", for
example, to the transmit power calculating portion 19 as a transmit
power variation amount, when the likelihood of the transmit power
controlling signal to be input is .alpha.+ or more. Similarly, the
likelihood-transmit power variation amount converting portion 73
outputs "-1 dB", for example, to the transmit power calculating
portion 19 as a transmit power variation amount, when the
likelihood of the transmit power controlling signal to be input is
less than .alpha.-. The likelihood-transmit power variation amount
converting portion 73 outputs a transmit power variation amount,
which varies as shown as the line 74 in FIG. 12, for example, to
the transmit power calculating portion 19 in accordance with the
likelihood of the transmit power controlling signal. The operation
thereafter to the transmission of the transmission signal from the
antenna 10 is same as that of the first embodiment.
[0091] An example of a change of transmit power of a mobile station
in the case that the mobile station performs an operation in the
third embodiment is shown as a solid line 65 in FIG. 13. As shown
in FIG. 13, the mobile station controls the transmit power so that
the variation amount of the transmit power would be a value smaller
than "+1 dB" and "-1 dB" during the time 103 in which the
likelihood of the transmit power controlling signal is .alpha.- or
more and less than .alpha.+.
[0092] A structure of the mobile station in the fourth embodiment
is shown in FIG. 14. Elements corresponding to a structure of the
mobile stations shown in FIGS. 32 and 1 are marked with the same
reference number. The likelihood of the transmit power controlling
signal calculated in the transmit power controlling signal
likelihood calculating portion 30 is input to the transmit power
variation amount calculating portion 31, as same as in the first
embodiment.
[0093] A structure of the transmit power variation amount
calculating portion 31 in the fourth embodiment is shown in FIG.
15. The likelihood determining portion 130 generates a controlling
signal for selecting either "+1 dB (increase)" or "-1 dB
(decrease)", for example, as a variation amount of the transmit
power on the basis of the likelihood of the transmit power
controlling signal input from the transmit power controlling signal
likelihood calculating portion 30 to output the generated signal to
a selector 131. An example of an operation of the likelihood
determining portion 130 in the fourth embodiment is shown in FIG.
16. The likelihood determining portion 130 outputs to the selector
131 a controlling signal such that "+1 dB" is selected in the
selector 131, when the likelihood of the transmit power controlling
signal to be input exists within an area of 0 or more. On the other
hand, the likelihood determining portion 130 outputs to the
selector 131 a controlling signal such that "-1 dB" is selected,
when the likelihood of the transmit power controlling signal to be
input exists within an area less than 0. The selector 131 selects
the transmit power variation amount in accordance with the
controlling signal from the likelihood determining portion 130 to
output the variation amount to the transmit power calculating
portion 19 shown in FIG. 14. The transmit power calculating portion
19 calculates the transmit power of the mobile station as same as
in the first embodiment.
[0094] The transmit power limiting portion 32 compares the transmit
power calculated in the transmit power calculating portion 19 and
the transmit power limit value calculated inside the transmit power
limiting portion 32 to control the transmit power of the mobile
station. A structure of the transmit power limiting portion 32 is
shown in FIG. 17. The transmit power input from the transmit power
calculating portion 19 is input to a transmit power limit value
calculating portion 90 and a comparing portion 91. An example of an
operation of the transmit power limit value calculating portion 90
is shown in FIG. 18. In the transmit power limit value calculating
portion 90, the likelihood of the transmit power controlling signal
input from the transmit power controlling signal likelihood
calculating portion 30 is first compared with thresholds .beta.-
and .beta.+. When the likelihood of the transmit power controlling
signal cannot establish a relation .apprxeq.-.ltoreq.(likelih- ood)
<.beta.+, that is, when the absolute value of the likelihood of
the transmit power controlling signal is large, the upper limit
value TXPU of the transmit power and the lower limit value TXPL of
the transmit power are updated. According to this operation, the
upper and lower limit values of the transmit power of the mobile
station are calculated when the absolute value of the likelihood of
the transmit power controlling signal is large, that is, when the
receiving quality of the transmit power controlling signal is good,
while the upper and lower limit values of the transmit power of the
mobile station are maintained when the absolute value of the
likelihood of the transmit power controlling signal is small, that
is, when the receiving quality of the transmit power controlling
signal is bad.
[0095] The comparing portion 91 shown in FIG. 17 compares the
transmit power input from the transmit power calculating portion 19
and the upper and lower limit values of the transmit power input
from the transmit power limit value calculating portion 90. The
comparing portion 91 changes the transmit power into TXPU to output
it to the transmit power maintaining circuit 20 and the variable
gain amplifier 21 shown in FIG. 14, when the transmit power input
from the transmit power calculating portion 19 is larger than the
upper limit value TXPU of the transmit power input from the
transmit power limit value calculating portion 90. On the other
hand, the comparing portion 91 changes the transmit power into TXPL
to output it to the transmit power maintaining circuit 20 and the
variable gain amplifier 21 shown in FIG. 14, when the transmit
power input from the transmit power calculating portion 19 is
smaller than the lower limit value TXPL of the transmit power input
from the transmit power limit value calculating portion 90.
Further, the comparing portion 91 outputs the transmit power input
from the transmit power calculating portion 19 to the transmit
power maintaining circuit 20 and the variable gain amplifier 21
shown in FIG. 14, as it is, when the transmit power input from the
transmit power calculating portion 19 is between TXPU and TXPL. The
operation thereafter to the transmission of the transmission signal
from the antenna 10 is same as that of the first embodiment.
[0096] An example of a change of transmit power of a mobile station
in the case that the mobile station performs an operation in the
fourth embodiment is shown as a solid line 66 in FIG. 19. As shown
in FIG. 19, the upper limit value TXPU and the lower limit value
TXPL of the transmit power of the mobile station are maintained at
a certain value during the time 103 in which the likelihood of the
transmit power controlling signal is .alpha.- or more and less than
.alpha.+. In the example shown in FIG. 19, the transmit power of
the mobile station is limited not so as to be less than the lower
value TXPL of the transmit power during the time 103.
[0097] In the fourth embodiment, the transmit power variation
amount calculating portion 31 may have a structure shown in the
first to third embodiments.
[0098] A structure of a mobile station in the fifth embodiment is
shown in FIG. 20. Elements corresponding to a structure of the
mobile stations shown in FIGS. 32 and 1 are marked with the same
reference number. The likelihood of the transmit power controlling
signal calculated in the transmit power controlling signal
likelihood calculating portion 30 is input to the transmit power
variation amount calculating portion 31, as same as in the first
embodiment. The transmit power variation amount calculating portion
31 may have any structure and operation of the transmit power
variation amount calculating portion 31 described in the first to
fourth embodiments. The variation amount of the transmit power
calculated in the transmit power variation amount calculating
portion 31 is input to the transmit power calculating portion
19.
[0099] The transmit power calculating portion 19 calculates the
transmit power of the mobile station as same as in the first
embodiment.
[0100] The transmit power calculated in the transmit power
calculating portion 19 is input to a transmit power selecting
portion 33. The transmit power selecting portion 33 selects the
transmit power in accordance with the likelihood of the transmit
power controlling signal input from the transmit power controlling
signal likelihood calculating portion 30.
[0101] A structure of the transmit power selecting portion 33 in
the fifth embodiment is shown in FIG. 21. A likelihood determining
portion 140 generates a controlling signal for selecting as the
transmit power either the transmit power input from the transmit
power calculating portion 19 or the transmit power input from a
transmit power averaging portion 142 on the basis of the likelihood
of the transmit power controlling signal input from the transmit
power controlling signal likelihood calculating portion 30, and
outputs the generated signal to a selector 141. An example of an
operation of the likelihood determining portion 140 in the fifth
embodiment is shown in FIG. 22. The likelihood determining portion
140 outputs to the selector 141 a controlling signal such that the
transmit power input from the transmit power calculating portion 19
is selected in the selector 141, when the likelihood of the
transmit power controlling signal to be input exists within an area
104, which is .gamma.+ or more, or an area 106, which is less than
.gamma.-, namely, when the receiving quality of the received
transmit power controlling signal is good. On the other hand, the
likelihood determining portion 140 outputs to the selector 141 a
controlling signal such that the transmit power input from the
transmit power averaging portion 142 is selected, when the
likelihood of the transmit power controlling signal to be input
exists within an area 105, which is .gamma.- or more and less than
.gamma.+, namely, when the receiving quality of the received
transmit power controlling signal is bad. The selector 141 selects
the transmit power in accordance with the controlling signal from
the likelihood determining portion 140 to output the transmit power
to a transmit power maintaining circuit 20 and a variable gain
amplifier 21 shown in FIG. 20. The transmit power averaging portion
142 calculates an average value of the transmit power to be input
so as to output the average value to the selector 141.
[0102] The operation thereafter to the transmission of the
transmission signal from the antenna 10 is same as that of the
first embodiment.
[0103] Next, an operation of a mobile station of the sixth
embodiment will be described. A structure of the mobile station in
the sixth embodiment is shown in FIG. 20 as same as that in the
fifth embodiment. In the sixth embodiment, a structure of the
transmit power selecting portion 33 is different from that of the
fifth embodiment. The structure of the transmit power selecting
portion 33 in the sixth embodiment is shown in FIG. 23. A
likelihood determining portion 150 generates a controlling signal
for selecting as the transmit power either the transmit power input
from the transmit power calculating portion 19 or the transmit
power input from an open loop transmit power calculating portion
152 on the basis of the likelihood of the transmit power
controlling signal input from the transmit power controlling signal
likelihood calculating portion 30, and outputs the generated signal
to a selector 151. An example of an operation of the likelihood
determining portion 150 in the sixth embodiment is shown in FIG.
24. The likelihood determining portion 150 outputs to the selector
151 a controlling signal such that the transmit power input from
the transmit power calculating portion 19 is selected in the
selector 151, when the likelihood of the transmit power controlling
signal to be input exists within an area 107, which is .delta.+ or
more, or an area 109, which is less than .delta.-, namely, when the
receiving quality of the received transmit power controlling signal
is good.
[0104] On the other hand, the likelihood determining portion 150
outputs to the selector 151 a controlling signal such that the
transmit power input from the open loop transmit power calculating
portion 152 is selected, when the likelihood of the transmit power
controlling signal to be input exists within an area 108, which is
.delta.- or more and less than .delta.+, namely, when the receiving
quality of the received transmit power controlling signal is bad.
The selector 151 selects the transmit power in accordance with the
controlling signal from the likelihood determining portion 150 to
output the transmit power to the transmit power maintaining circuit
20 and the variable gain amplifier 21 shown in FIG. 20.
[0105] The open loop transmit power calculating portion 152 uses
the receiving quality, the receiving power and the like of a
channel different from the channel being used for a communication
such as a perch channel in the W-CDMA mode, for example, so as to
estimate the attenuation amount between a mobile station and a base
station, and calculates the transmit power of the mobile station,
which meets the receiving quality required in the base station. The
open loop transmit power calculating portion 152 outputs the
calculated transmit power to the selector 151.
[0106] The operation thereafter to the transmission of the
transmission signal from the antenna 10 is same as that of the
first embodiment.
[0107] A structure of a base station in the seventh embodiment is
shown in FIG. 25. Elements corresponding to a structure of a
conventional base station shown in FIG. 29 are marked with the same
reference number. A received signal is measured for SIR (SIRa to
SIRn) per a mobile station (MSa to MSn) in the upstream channel SIR
measuring portion 221 to be input through signal lines 230a to 230n
into an upstream channel transmit power controlling signal
generating portion 250 as same as in the conventional base
station.
[0108] The upstream channel transmit power controlling signal
generating portion 250 generates a transmit power controlling
signal for MSa to MSn (referred to as TPCa to TPCn) on the basis of
a comparison result between SIRa to SIRn and a target SIR, which is
given in advance from a controlling portion 501 for MSa to MSn
(referred to as T-SIRa to T-SIRn), and of RXa to RXn, which are a
controlling signal showing whether a receiving operation is
performed for a signal transmitted from the MSa to MSn and which
are input from the controlling portion 501. The controlling portion
501 is further provided with a function for supplying the upstream
channel transmit power controlling signal generating portion 250
with RXa to RXn, in addition to a function same as the controlling
portion 500 of the conventional base station shown in FIG. 29. When
a normal communication is carried out between MSi (i=a, . . . , n)
and the base station, RXi (i=a, . . . , n) is a signal whose
content indicates that a receiving operation is going on for the
signal transmitted from MSi. On the other hand, when a normal
communication cannot be maintained between MSi and the base station
due to an influence of such as being in shade, so that the base
station stops receiving a signal from MSi, RXi is a signal whose
content indicates that the receiving operation is not performed for
the signal transmitted from MSi.
[0109] A structure of the upstream channel transmit power
controlling signal generating portion 250 is shown in FIG. 26. The
upstream channel transmit power controlling signal generating
portion 250 comprises transmit power controlling signal generating
portions 250a to 250n whose inputs are SIRi, T-SIRi and RXi and
whose outputs are TPCi. The added character "i" denotes one of
characters "a" to "n". A structure of a transmit power controlling
signal generating portion 250i is shown in FIG. 27. A comparator
254i compares SIRi input through a signal line 230i and T-SIRi to
generate a signal that selects 0 (a signal instructing to decrease
the transmit power) in a selector 251i in the case of
SIRi.gtoreq.T-SIRi, and a signal that selects 1 (a signal
instructing to increase the transmit power) in the selector 251i in
the case of SIRi<T-SIRi. The selector 251i selects 0 or 1 in
accordance with an output from the comparator 254i to output it
through a signal line 252i to a selector 253i. The selector 253i
determines the transmit power controlling signal TPCi in accordance
with the signal RXi indicating whether a receiving operation is
going on or not. An operation of the selector 253i is shown in FIG.
28. The selector 253i selects a signal input as the transmit power
controlling signal TPCi through a signal line 252i, when RXi is a
signal indicating that a receiving operation is going on. On the
contrary, the selector 253i selects 0 (a signal instructing to
decrease the transmit power) as the transmit power controlling
signal TPCi when RXi is a signal indicating that a receiving
operation has been stopped.
[0110] The transmit power controlling signals TPCa to TPCn for MSa
to MSn generated in the above method are input through signal lines
231a to 231n into frame forming portions 225a to 225n to take
processes similar to the case of the conventional base station
before being transmitted from the antenna 210.
[0111] A mobile station according to the invention does not cause
an error in controlling the transmit power even in the case of
receiving the transmit power controlling signal, which includes an
error in receiving. That is, transmission at excessive transmit
power due to incorrect control or out-of control can be prevented,
so that the number of subscribers contained in a system can be
increased, compared with the conventional case. Further, the power
supply of a mobile station can be saved since the transmission is
not carried out at excessive transmit power.
[0112] According to the radio base station according to the
invention, it can be possible to prevent a mobile station from
transmitting at excessive transmit power by controlling the mobile
station not to transmit an improper transmit power controlling
signal after stopping a receiving operation for the signal to be
transmitted. Thus, deterioration of the communication quality due
to an error in controlling power can be avoided and the subscriber
capacity of a whole system can be significantly improved.
* * * * *