U.S. patent application number 09/185507 was filed with the patent office on 2001-08-16 for transmission power control method and transmission/reception apparatus.
This patent application is currently assigned to MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.. Invention is credited to UESUGI, MITSURU.
Application Number | 20010014612 09/185507 |
Document ID | / |
Family ID | 18222719 |
Filed Date | 2001-08-16 |
United States Patent
Application |
20010014612 |
Kind Code |
A1 |
UESUGI, MITSURU |
August 16, 2001 |
TRANSMISSION POWER CONTROL METHOD AND TRANSMISSION/RECEPTION
APPARATUS
Abstract
Slot quality detector 121 detects a reception level, and power
controller inversely corresponding to reception quality 122 outputs
power control information indicative of increasing transmission
power in the case where the detected reception level is higher than
a threshold value and of decreasing the transmission power in the
case where the detected quality is lower than the threshold value.
Transmission power setter 108 performs the setting of transmission
power corresponding to the power control information and provides a
control to transmit by the set power. That allows improving of a
battery saving and moderating of the specification of amplifiers in
a transmission/reception apparatus, thereby resulting in decreased
interference to signals of other users in the CDMA
communication.
Inventors: |
UESUGI, MITSURU;
(YOKOSUKA-SHI, JP) |
Correspondence
Address: |
GREENBLUM & BERNSTEIN
1941 ROLAND CLARKE PLACE
RESTON
VA
20191
|
Assignee: |
MATSUSHITA ELECTRIC INDUSTRIAL CO.,
LTD.
OSAKA
JP
|
Family ID: |
18222719 |
Appl. No.: |
09/185507 |
Filed: |
November 4, 1998 |
Current U.S.
Class: |
455/522 ;
370/342; 455/69 |
Current CPC
Class: |
H04W 52/225 20130101;
H04W 52/12 20130101; H04W 52/20 20130101; H04W 52/08 20130101 |
Class at
Publication: |
455/522 ;
370/342; 455/69 |
International
Class: |
H04B 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 13, 1997 |
JP |
9-329559 |
Claims
What is claimed is:
1. A transmission power control method comprising the steps of:
detecting a quality of a received signal; generating power control
information indicative of increasing transmission power in the case
where the detected quality is higher than a threshold value and of
decreasing said transmission power in the case where said detected
quality is lower than said threshold value; and transmitting the
power control information.
2. The transmission power control method according to claim 1, said
method further comprises a step of calculating an average of
reception power for a predetermined interval and deciding the
threshold value corresponding to the calculation result.
3. A radio communication apparatus comprising: quality detecting
means for detecting a quality of a received signal; power control
inversely corresponding to quality means for outputting power
control information indicative of increasing transmission power in
the case where the detected quality is higher than a threshold
value and of decreasing said transmission power in the case where
said detected quality is lower than said threshold value.
4. The radio communication apparatus according to claim 3, said
apparatus further comprises averaged reception power calculating
means for calculating an average of reception power for a
predetermined interval, wherein said power control inversely
corresponding to quality means decides the threshold value
corresponding to the calculation result.
5. A radio communication apparatus comprising: reception means for
receiving power control information indicative of increasing
transmission power in the case where a quality is higher than a
threshold value and of decreasing said transmission power in the
case where said quality is lower than said threshold value;
transmission power setting means for performing the setting of
transmission power corresponding to said power control information;
and transmission means for performing a transmission by the set
power.
6. The radio communication apparatus according to claim 5, said
apparatus further comprises averaged reception power calculating
means for obtaining an average of said power control information,
wherein said transmission power setting means decides the
transmission power corresponding to said calculation result.
7. A transmission/reception apparatus comprising: a receiver having
quality detecting means for detecting a quality of a received
signal, and power control inversely corresponding to quality means
for outputting power control information indicative of increasing
transmission power in the case where the detected quality is higher
than a threshold value and of decreasing said transmission power in
the case where said detected quality is lower than said threshold
value; and a transmitter having reception means for receiving said
power control information, transmission power setting means for
performing the setting of transmission power according to
corresponding to said power control information, and transmission
means for performing a transmission by the set power.
8. The transmission/reception apparatus according to claim 7, said
apparatus further comprises averaged reception power calculating
means for calculating an average of reception power for a
predetermined interval, wherein said power control inversely
corresponding to quality means decides the threshold value
corresponding to the calculation result.
9. The transmission/reception apparatus according to claim 7, said
apparatus further comprises averaged transmission power calculating
means for obtaining an average of said power control information,
wherein said transmission power setting means decides the
transmission power corresponding to said calculation result.
10. A base station apparatus having a transmission/reception
apparatus, said transmission/reception apparatus comprising: a
receiver having quality detecting means for detecting a quality of
a received signal, and power control inversely corresponding to
quality means for outputting power control information indicative
of increasing transmission power in the case where the detected
quality is higher than a threshold value and of decreasing said
transmission power in the case where said detected quality is lower
than said threshold value; and a transmitter having reception means
for receiving said power control information, transmission power
setting means for performing the setting of transmission power
corresponding to said power control information, and transmission
means for performing a transmission by the set power.
11. A communication terminal apparatus having a
transmission/reception apparatus, said transmission/reception
apparatus comprising: a receiver having quality detecting means for
detecting a quality of a received signal, and power control
inversely corresponding to quality means for outputting power
control information indicative of increasing transmission power in
the case where the detected quality is higher than a threshold
value and of decreasing said transmission power in the case where
said detected quality is lower than said threshold value; and a
transmitter having reception means for receiving said power control
information, transmission power setting means for performing the
setting of transmission power corresponding to said power control
information, and transmission means for performing a transmission
by the set power.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a transmission power
control method and a transmission/reception apparatus, which are
used in a CDMA (Code Division Multiple Access) that is a digital
radio communication and so on, capable of controlling transmission
power optimally for a battery saving in a mobile station apparatus
and so on.
[0003] 2. Description of the Related Art
[0004] In a conventional transmission/reception apparatus using a
transmission power control, the transmission power is controlled to
be increased in the case where a reception quality decreases by a
decrease of a reception level due to fading, or the like, and to be
decreased in the case of a good reception quality.
[0005] FIG. 1 is a block diagram illustrating a schematic
configuration of a conventional CDMA transmission/reception
apparatus. In FIG. 1, transmission data 1 is subjected to error
correction coding in error correction coder 2, and interleaved in
interleaver 3. Then the data is spread with a predetermined
spreading code in spreader 4, demodulated in demodulator 5,
amplified in transmission amplifier 6, and transmitted from
transmission antenna 7.
[0006] At this time, transmission amplifier 6 amplifies the
transmission power to the level set by transmission power setter 8.
This example illustrates an example of diversity reception.
Therefore, in a receiver, signals are received in first reception
antenna 11 and in second reception antenna 12, detected in first
detector 13 and in second detector 14 respectively, despread in
first despreader 15 and in second despreader 16 respectively, then
synthesized in synthesizer 17.
[0007] In the case where a plurality of paths present in a
communication link due to the effect of delayed versions and so on,
RAKE combining is also performed in synthesizer 17. The synthesized
data are deinterleaved in deinterleaver 18, subjedted to error
correction in error correction decoder 19 to obtain reception data
20.
[0008] In the receiver, slot quality detector 21 detects a slot
quality of reception data 20. In detail, at step ST1 of a flow
chart illustrated in FIG. 2, the quality of the slot (a block of
data with a certain length) is detected. At this step, as
illustrated in FIG. 3, it is decided whether or not the slot
quality (reception quality) 31 is higher than threshold value
32.
[0009] Based on the decision result, power controller corresponding
to reception quality 22 (hereinafter abbreviated as power
controller-CRQ 22) controls the transmission power to be decreased
at step ST2 in the case where reception quality (reception level)
31 is higher (better) than threshold value 32. On the other hand,
power controller-CRQ 22 controls the transmission power to be
increased at step ST3 in the case where the reception quality is
lower than the threshold value. In detail, power controller-CRQ 22
provides a control as illustrated by rectangle line 34 in FIG. 3.
Then, at step ST4, transmits power control information is
transmitted to transmission power setter 8 in a transmitter.
[0010] FIG. 3 is a diagram illustrating the control of power
controller-CRQ 22 for reverse link signals (signals transmitted
from mobile station MS to base station BS). In FIG. 3, the fading
between transmission side MS and reception side BS illustrated by
curve 36 and the transmission power of mobile side MS illustrated
by curve 38 are almost in inverse proportion.
[0011] Thus, it is possible to keep the reception quality almost
constant, thereby allowing the improvement of the error correction
ability in the case of using the error correction code having high
resistance to random errors, such as convolutional code. However,
there is a factor that a transmission power control error or
interference volume changes, interleaving are performed to make
errors further random.
[0012] According to the manner described above, the transmission
power control corresponding to the reception quality always allows
using of the minimum level of transmission power needed to keep the
quality constant, thereby resulting in a battery saving of the
mobile station. In addition, that also allows improving of system
capacity because the interference volume is decreased by
suppressing an unnecessary transmission power in the CDMA
communication system.
[0013] However, in the conventional reception/transmission
apparatus descried above, the transmission power is controlled to
be increased in the case where the reception quality decreases by
the decrease of the reception level due to the fading, or the like,
and to be decreased in the case of the good communication quality.
In the case where the reception level decreases due to the fading,
it is necessary to increase the transmission level to tens of dB to
transmit, which requires a transmission amplifier to have a large
dynamic range. However, especially in the mobile station, the
requirements for a battery life and specification on amplifiers
have become severe, which makes it difficult to use an amplifier
with the large dynamic range. In addition, the increase of the
level makes the instant interference (to signals of other users)
high in the CDMA communication.
SUMMARY OF THE INVENTION
[0014] The object of the present invention is to provide a
transmission power control method and a transmission/reception
apparatus capable of satisfying severe requirements for a batter
life and specification on amplifiers, and of decreasing
interference to signals of other users in a CDMA communication.
[0015] The present inventor was interested in the fact that an
increase of transmission power did not improve an quality to an
expected degree when a power level was decreased depending on level
variations due to fading, and found the fact that an excess
increase of the transmission power can be prevented by decreasing
the transmission power to abandon such portion of communications in
the case of level variations due to the fading, thus resulting in
the present invention.
[0016] That is, the principle of the present invention is as
follows. The transmission/reception apparatus in the reception side
detects the reception level and provides the power control to the
transmission side to increase the transmission power in the case
where the detected reception level is higher than a threshold
value, and decrease the transmission power in the case where the
detected reception level is lower than the threshold value, and the
transmission side thus performs a transmission by the power
according to the power control.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a block diagram of a conventional CDMA
transmission/reception apparatus;
[0018] FIG. 2 is a flow chart to explain an operation of the
conventional CDMA transmission/reception apparatus;
[0019] FIG. 3 is a diagram to explain a power control corresponding
to reception quality in the conventional CDMA
transmission/reception apparatus;
[0020] FIG. 4 is a block diagram of a CDMA transmission/reception
apparatus according to the first embodiment of the present
invention;
[0021] FIG. 5 is a flow chart to explain an operation of the CDMA
transmission/reception apparatus according to the above
embodiment;
[0022] FIG. 6 is a diagram to explain a power control inversely
corresponding to reception quality in the CDMA
transmission/reception apparatus according to the above
embodiment;
[0023] FIG. 7 is a block diagram of a CDMA transmission/reception
apparatus according to the second embodiment of the present
invention;
[0024] FIG. 8 is a flow chart to explain an operation of the CDMA
transmission/reception apparatus according to the above embodiment;
and
[0025] FIG. 9 is a block diagram of a CDMA transmission/reception
apparatus according to the third embodiment of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] In a transmission power control method of the present
invention, a transmission/reception apparatus in a reception side
detects a reception level, and provides a power control to the
transmission side to increase the transmission power in the case
where the detected reception level is higher than a threshold
value, and decrease the transmission power in the case where the
detected reception level is lower than the threshold value, and the
transmission side thus performs a transmission by the power
according to the power control.
[0027] According to this method, since the transmission power
control inversely corresponding to the reception quality is
performed, an averaged transmission power can be decreased, thereby
resulting in more battery saving of the transmission/reception
apparatus than conventional apparatuses and the suppressed peak
transmission power. That allows moderating of the specification of
amplifiers, especially allows reducing of a cost and power
consumption of the transmission/reception apparatus.
[0028] In addition, in this transmission power control method, it
is preferable in the reception side to calculate a long-term
reception power average and determine the threshold value
corresponding to the calculation result. By this manner, it is
possible to obtain the same effect as the manner described above,
and prevents the transmission power from decreasing according to an
attenuation due to a long-term variation, by reflecting the
calculation result of the averaged reception power.
[0029] In addition, in this transmission power control method, it
is preferable in the transmission side to calculate an average of
transmission power control information and determine the
transmission power corresponding to the calculation result. By this
manner, it is possible to obtain the same effect as the manner
described above, and perform further effective transmission power
control by calculating the averaged transmission power.
[0030] In addition, the transmission/reception apparatus of the
present invention comprises a receiver having a reception quality
detecting section for detecting the reception quality and a power
control inversely corresponding to reception quality section for
outputting power control information of increasing the transmission
power in the case where the detected reception level is higher than
the threshold value and decreasing the transmission power in the
case where the reception level is lower than the threshold value,
and also comprises a transmitter having a transmission power
setting section for setting the transmission power corresponding to
the power control information and providing a control to transmit
according to the set power.
[0031] According to the constitution, since the transmission power
control inversely corresponding to reception quality is performed,
the averaged transmission power can be decreased, thereby resulting
in more battery saving of the transmission/reception apparatus than
conventional apparatuses and the suppressed peak transmission
power. That allows moderating of the specification of amplifiers,
especially allows reducing of a cost and power consumption of the
transmission/reception apparatus.
[0032] In addition, in this transmission/reception apparatus, the
receiver comprises an averaged reception power calculating section
for calculating the long-term reception power average, and the
power control inversely corresponding to reception quality section
determines the threshold value corresponding to the calculation
result.
[0033] According to this manner, it is possible to obtain the same
effect as the manner described above, and prevents the transmission
power from decreasing according to the attenuation due to the
long-term variation, by reflecting the calculation result of the
averaged reception power.
[0034] In addition, in the transmission/reception apparatus, the
transmitter comprises an averaged transmission power calculating
section for obtaining an average of the power control information,
and the transmission power setting section determines the
transmission power corresponding to the calculation result.
According to the constitution, it is possible to obtain the same
effect as the manner described above, and perform further effective
transmission power control by calculating the averaged transmission
power.
[0035] In addition, it is preferable in the transmission/reception
apparatus that the transmitter and the receiver comprise the
constitutions to perform the CDMA communication. According to the
constitution, in the CDMA communication, it is possible to improve
the system capacity more than the conventional constitution because
the decrease of the averaged transmission power results in the
decrease of interference volume.
[0036] Hereinafter, the embodiments of the present invention are
explained with reference to attached drawings in detail.
[0037] First Embodiment
[0038] FIG. 4 illustrates a block diagram of a CDMA
transmission/reception apparatus in the first embodiment of the
present invention. In FIG. 4, transmission data 101 is subjected to
error correction coding in error correction coder 102, and
interleaved in interleaver 103. Then the data are spread with a
spreading code in spreader 104, demodulated in demodulator 105,
amplified in transmissions amplifier 106, and transmitted from
transmission antenna 107.
[0039] At this time, transmission amplifier 106 amplifies the
transmission power to the level set by transmission power setter
108. This example illustrates an example of diversity reception.
Therefore, in a receiver, signals are received in first reception
antenna 111 and in second reception antenna 112, detected in first
detector 113 and in second detector 114 respectively, despread in
first despreader 115 and in second despreader 116 respectively,
then synthesized in synthesizer 17.
[0040] In the case where a plurality of paths present in a
communication link due to the effect of delayed versions and so on,
RAKE combining is also performed in synthesizer 117. The
synthesized data are deinterleaved in deinterleaver 118, subjedted
to error correction in error correction decoder 119 to obtain
reception data 120.
[0041] In the receiver, slot quality detector 121 detects a slot
quality of reception data 120. In detail, at step ST101 of a flow
chart illustrated in FIG. 5, the quality of the slot (a block of
data with a certain length) is detected. At this step, it is
decided whether or not the slot quality (reception quality) 201 is
higher than threshold value 202.
[0042] Based on the decision result, power control inversely
corresponding to reception quality section 122 (hereinafter
abbreviated as power control-ICRQ 122) generates the power control
information so as to increase the transmission power at step ST2 as
illustrated by rectangle line 204 in FIG. 6 in the case where
reception quality (reception level) 201 is higher (better) than
threshold value 202 and to decrease the transmission power at step
ST103 in the case where the reception quality is lower than
threshold value 202. Then at step ST104, the power control
information is transmitted to transmission power setter 108 in the
transmitter.
[0043] A logic diagram of power control-ICRQ section 122
illustrated in FIG. 6 shows an example of reverse link signals
(signals transmitted from mobile station MS to base station BS).
The transmission power in mobile side MS illustrated by curve 208
indicates almost similar variations with the fading between
transmission side MS and reception side BS illustrated by curve
206.
[0044] Two kinds of reception qualities thus are available, i.e.,
extremely good reception quality and extremely poor reception
quality. In the case of using the error correction code having high
resistance to random errors, such as convolutional code, the
correction ability is hold by interleaving to make errors
random.
[0045] When the transmission power control illustrated in FIG. 6 is
performed, it is not necessary to transmit by high power in the
case where the reception level more than a certain level is kept by
the level variation due to fading. Therefore, transmission power
setter 108 controls the transmission power (under a certain power
level) not to transmit in the receiver by higher power than a
certain power level after the power level reaches the certain power
level even in the case where power control-ICRQ section 122
instructs to increase the transmission power.
[0046] The maximum MS transmission power thus is controlled under
the power level that is too high. On the other hand, in the case
where the level is under the certain level by the level variation
due to fading (the level variation due to fading is under the
certain level) it is not reasonable to transmit by compulsory high
transmission power because good enough quality may not be obtained.
In such case, the transmission power is decreased to abandon such
poor quality, thereby reducing the transmission power.
[0047] In this case, error correction decoder 119 extremely lowers
the likelihood of soft decision decoding. The case of performing
the error correction and interleaving is equivalent to the case of
puncture, and a correct demodulation is performed in the case of a
low degree of the error correction and the interleaving. Thus, by
setting in transmission power setter 108 the transmission power
with the transmission power value controlled by power
controller-ICRQ 122, the averaged transmission power and the peak
transmission power is reduced.
[0048] In a transmission of packets and so on, the packet that
could not be transmitted is retransmitted. It is supposed that the
effect of decreasing the entire transmission power is more
effective than the effect of increasing the transmission power to
retransmit, and also supposed that FER (Frame Error Rate) is less
than random errors by not performing the interleaving.
[0049] Thus, according to the first embodiment, since the
transmission power control inversely corresponding to reception
quality is performed along with interleaving, error correction and
so on, the averaged transmission power can be reduced. Therefore,
the battery saving of the mobile station is achieved more than the
conventional apparatuses and the peak transmission power is
suppressed. That allows moderating of the specification of
amplifiers, further reducing of the cost and power consumption of
the transmission/reception apparatus. In addition, it is possible
to improve the system capacity more than the conventional
constitution because the decrease of the averaged transmission
power results in the decrease of interference (volume) in the CDMA
system.
[0050] Second Embodiment
[0051] FIG. 7 illustrates a block diagram of a CDMA
transmission/reception apparatus according to the second embodiment
of the present invention. In addition, in the second embodiment of
the present invention illustrated in FIG. 7, a section
corresponding to each section in the first embodiment illustrated
in FIG. 4 is assigned the same symbol to omit the explanation.
[0052] The second embodiment illustrated in FIG. 7 is characterized
by having averaged reception power calculator 301 for calculating a
long-term variations of the reception level caused by an
attenuation of communication distance to be reflected in a
threshold value in power controller-ICRQ 302 so that the
appropriate transmission power control is performed.
[0053] That is, in the receiver, at step ST201 illustrated in the
operation flow chart of the power control inversely corresponding
to reception quality in FIG. 8, averaged reception power calculator
301 calculates, using data output from synthesizer 117, the
long-term variations of the reception level caused by the
attenuation of communication distance and so on, and updates the
threshold value of power controller-ICRQ 122 corresponding to the
calculation result. The update is performed to increase the
threshold value when the calculation value is high, which is
assumed that the attenuation is low, and to decrease the threshold
value when the calculation value is low.
[0054] Then, slot quality detector 121 detects a slot quality based
on reception data 120 at step ST202, and decides whether or not the
slot quality is higher than the threshold value.
[0055] Based on the decision result, power controller-ICRQ 122
generates the power control information indicative of increasing
the transmission power at step ST203 in the case where the
reception quality is higher (better) than the threshold value, and
of decreasing the transmission power at step ST204 in the case
where the reception quality is lower than the threshold value.
Then, at step ST205, the power control information is transmitted
to transmission power setter 108 in the transmitter.
[0056] When a cell radius is large, it is supposed that the
long-term level variation generates by a difference of
communication distance and shadowing. In such case, the
transmission power decreases as the attenuation of the long-term
variation if the threshold value of power controller-ICRQ 122 is
fixed in the same way as the first embodiment.
[0057] However, the above problem that the transmission power
decreases as the attenuation of the long-term variation is solved
in the same way as the second embodiment, where averaged reception
power calculator 301 obtains the long-term averaged reception level
to update the threshold value. The more effective transmission
control than the first embodiment is thus performed.
[0058] As described above, according to the second embodiment, it
is possible to obtain the same effect as the first embodiment, and
also cancel the effect of decreasing the transmission power as the
attenuation of the long-term variation by reflecting the
calculation result of the averaged reception power.
[0059] Third Embodiment
[0060] FIG. 9 illustrating a block diagram of a CDMA
transmission/reception apparatus according to the third embodiment
of the present invention. In addition, in the third embodiment of
the present invention illustrated in FIG. 9, a section
corresponding to each section in the second embodiment illustrated
in FIG. 7 is assigned the same symbol to omit the explanation.
[0061] The third embodiment illustrated in FIG. 9 is characterized
by having averaged transmission power calculator 401 for deciding
an averaged transmission power not to incline the control
corresponding to the power control information from power
controller-ICRQ 122 to transmit to transmission power setter 108 so
that the upper limit of the transmission power is decided.
[0062] That is, in the receiver, slot quality detector 121 detects
a slot quality of reception data 120. According to the result,
power controller-ICRQ 122 generates the power control information
indicative of increasing the transmission power in the case where
the reception quality is higher (better) than a threshold value,
and of decreasing the transmission power in the case where the
reception quality is lower than the threshold value, and transmits
the power control information to transmission power setter 108 and
averaged transmission power calculator 401 in the transmitter.
[0063] Thus, averaged transmission power calculator 401 decides the
averaged transmission power not to incline the control from power
controller-ICRQ 122 to transmit to transmission power setter 108,
thereby deciding the upper limit of the transmission power.
[0064] That is, in the transmitter, averaged transmission power
calculator 401 detects the incline of the control from power
controller-ICRQ 122, then increases the upper limit of the
transmission power of transmission power setter 108 by deciding
that the communication distance is getting bigger in the case of
(inclining to increase the power) the continuous controls
indicative of increasing the power level from power controller-ICRQ
122, and decreases the upper limit of the transmission power of
transmission power setter 108 by deciding that the communication
distance is getting smaller in the case of (inclining to decrease
the power) the continuous controls indicative of decreasing the
power level from power controller-ICRQ 122. The more effective
transmission power control is thus performed than the second
embodiment.
[0065] As described above, according to the third embodiment, it is
possible to obtain the same effect as the second embodiment, and to
perform further effective transmission power control than the
second embodiment by calculating the averaged transmission
power.
[0066] The apparatuses according to the first embodiment to the
third embodiment described above are applicable to communication
terminal apparatuses as mobile station apparatuses and base station
apparatuses in a radio communication system. In addition, the first
embodiment to the third embodiment described above explain about
the case of applying the transmission/reception apparatus of the
present invention in the CDMA communication system, however the
transmission/reception apparatus of the present invention is
applicable to the other communications besides the CDMA. In
addition, the first embodiment to the third embodiment described
above explain about the case of using the reception level as the
reception quality, however in the present invention, SNR (Signal to
Noise ratio), CNR (Carrier to Noise ratio), SIR (Signal to
Interference ratio), FER (Frame Error Rate), BER (Bit Error Rate),
etc. are applicable as the reception quality.
[0067] As appeared in the above-mentioned explanation, it is
possible in the reception/transmission apparatus to improve the
battery life and moderate the specification on amplifiers, thereby
decreasing interference to signals of other users in the CDMA
communication.
* * * * *