U.S. patent application number 11/102430 was filed with the patent office on 2005-12-08 for communication system, communication method and communication apparatus.
This patent application is currently assigned to Sony Corporation. Invention is credited to Sakoda, Kazuyuki.
Application Number | 20050272458 11/102430 |
Document ID | / |
Family ID | 26586746 |
Filed Date | 2005-12-08 |
United States Patent
Application |
20050272458 |
Kind Code |
A1 |
Sakoda, Kazuyuki |
December 8, 2005 |
Communication system, communication method and communication
apparatus
Abstract
When a base station and a plurality of terminal stations
communicate with each other by radio, power control information for
instructing electric power of a signal transmitted to the base
station is multiplexed at the base station and transmission energy
is adjusted such that total transmission energy of the multiplexed
power control information becomes substantially a predetermined
value if the total transmission energy of the multiplexed power
control information is lower than the predetermined value.
Therefore, information such as power control information that
should be individually instructed to respective terminal stations
can satisfactorily be transmitted by a simple arrangement and a
simple processing.
Inventors: |
Sakoda, Kazuyuki; (Tokyo,
JP) |
Correspondence
Address: |
Jay H. Maioli
Cooper & Dunham
1185 Avenue of the Americas
New York
NY
10036
US
|
Assignee: |
Sony Corporation
|
Family ID: |
26586746 |
Appl. No.: |
11/102430 |
Filed: |
April 7, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11102430 |
Apr 7, 2005 |
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09798582 |
Mar 2, 2001 |
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6909704 |
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Current U.S.
Class: |
455/522 ;
455/69 |
Current CPC
Class: |
H04W 24/00 20130101;
H04W 52/58 20130101; H04W 48/08 20130101; H04W 52/34 20130101; H04W
88/08 20130101; H04W 88/02 20130101 |
Class at
Publication: |
455/522 ;
455/069 |
International
Class: |
H04B 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 3, 2000 |
JP |
P2000-059028 |
May 11, 2000 |
JP |
P2000-139043 |
Claims
1. A communication system in which a base station and a plurality
of terminal stations communicate by radio, comprising: a base
station having: data processing means for processing data
transmitted to each of said plurality of terminal stations;
reception power management means for providing power control
information individually prepared for the plurality of terminal
stations, wherein the power control information to each terminal
station is used to control the corresponding terminal station, so
that the corresponding terminal station increases a transmission
electric power or decreases the transmission electric power power
control information processing means for generating the power
control information for controlling a transmission of electric
power at each of said terminal stations and adjusting a
transmission energy such that a total transmission energy of
multiplexed power control information becomes substantially a
predetermined value when said total transmission energy of
multiplexed power control information is lower than a predetermined
threshold value; and transmission processing means for multiplexing
and transmitting signals processed by said data processing means
and said multiplexed power control information processed by said
power control information processing means; and said plurality of
terminal stations each have: measuring means for measuring a
communication state of a signal transmitted from said base station;
and transmission processing means for transmitting information on
said communication state measured by said measuring means by
electric power controlled based en upon said power control
information transmitted from said transmission processing means of
said base station. wherein said base station includes communication
connection setting means for rejecting a setting of a connection
with each of said plurality of terminal stations when said total
transmission energy obtained before said power control information
multiplexed by said power control information processing means of
said base station is adjusted is higher than said predetermined
threshold value.
2-6. (canceled)
7. A communication method in which a base station and a plurality
of terminal stations communicate by radio, comprising the steps of:
receiving power control information individually prepared for the
plurality of terminal stations, wherein the power control
information to each terminal station is used to control the
corresponding terminal station, so that the corresponding terminal
station increases a transmission energy or decreases the
transmission energy generating the power control information for
controlling electric power for a signal transmitted to said base
station from to said plurality of terminal stations; adjusting
transmission energy such that a total transmission energy of
multiplexed power control information becomes substantially a
predetermined value when said total transmission energy of said
multiplexed power control information is lower than a predetermined
threshold value; transmitting said multiplexed power control
information from said base station to the said plurality of
terminal stations; and rejecting a setting of a connection with one
of said terminal stations when said total transmission energy
obtained before said multiplexed power control information is
adjusted is higher than said predetermined threshold value.
8-12. (canceled)
13. A communication apparatus for communicating with a plurality of
terminal stations by radio, comprising: data processing means for
processing data transmitted to each of said terminal stations;
reception power management means for providing power control
information individually prepared for the plurality of terminal
stations, wherein the power control information to each terminal
station is used to control the corresponding terminal station, so
that the corresponding terminal station increases a transmission
electric power or decreases the transmission electric power power
control information processing means for individually generating
the power control information for controlling transmission electric
power at each of said terminal stations and adjusting a
transmission energy such that a total transmission energy of
multiplexed power control information becomes substantially a
predetermined value when said total transmission energy of said
multiplexed power control information is lower than a predetermined
threshold value; transmission processing means for multiplexing and
transmitting a signal processed by said data processing means and
said multiplexed power control information processed by said power
control information processing means; and communication connection
setting means for rejecting a setting of a connection with another
terminal station when said total transmission energy obtained
before said power control information multiplexed by said power
control information processing means is adjusted is higher than
said predetermined threshold value.
14-18. (canceled)
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention generally relates to a communication
system and a communication method suitable for use for a cellular
wireless communication system and a communication apparatus for use
in a base station of this communication system. More particularly,
this invention relates to a communication system, a communication
method and a communication apparatus suitable for use in a system
which transmits a CDMA (code division multiple access) signal by
radio, for example.
[0003] 2. Description of the Related Art
[0004] There is proposed a digital cellular wireless communication
system for effecting a data communication between a base station
and a plurality of terminal stations, in which down-link
communications are transmitted from the base station to the
terminal stations with a frame arrangement shown in FIGS. 1A and
1B. This digital cellular wireless communication system shows an
example of a transmission arrangement of a system called an HDR
(high data rate). FIG. 1A is a diagram showing a frame arrangement
in which slots of a unit length are located continuously. FIG. 1B
shows an arrangement of one slot in which there are disposed a
first data interval, a first pilot interval, a second data
interval, a third data interval, a first power control information
interval, a second pilot interval, a second power control
information interval and a fourth data interval, in that order. In
FIG. 1B, each power control information interval is shown as RPC
for simplicity.
[0005] As shown in FIG. 1B, a preamble signal is disposed at a part
of the starting portion of the first data interval. Data within the
preamble signal indicates a terminal station to which the data
within the slot is transmitted. The first to fourth data intervals
are set to be of the same duration. To be concrete, the first to
fourth data intervals are respectively set to be 464 chips, the
first and second pilot intervals are respectively set to be 96
chips, the first and second power control information intervals are
set to be 64 chips, respectively, and the length of one slot is set
to be 2176 chips, for example.
[0006] In the case of this digital cellular wireless communication
system, a data interval within one slot is allocated as an interval
for transmitting data to one terminal station. Accordingly, when
data should be transmitted from the base station to a plurality of
specific terminal stations, a plurality of terminal stations, for
example, transmit data by sequentially using one slot each. The
power control information intervals (RPC) located ahead of and
behind the second pilot interval individually transmit power
control information to respective terminal stations which are
communicating with the base station. The pilot interval is
fundamentally the interval in which data is received buy all
terminal station. This power control information is data for
designating a transmission electric power of an up-link through
which data is transmitted from each terminal station to the base
station and instructs individual terminal stations either to
increase a transmission power or decrease a transmission power.
[0007] In order to simultaneously and individually transmit the
power control information to individual terminal stations, in the
proposed system according to the related art, power control
information for each terminal station is spread by using a code
allocated to every terminal station and the power control
information thus spread for each terminal station are multiplexed
and then transmitted. The processing in which a plurality of data
thus spread by using the code corresponds to a CDMA (code division
multiple access) system processing.
[0008] FIG. 1c is a diagram showing the manner in which power
control information is transmitted in the first and second power
control information intervals. In this example, power control
information is simultaneously transmitted to six terminal stations
of users #0 to #5, and power control information for six terminal
stations are held at the same transmission electric power, spread,
multiplexed and then-transmitted.
[0009] Transmission electric powers of all signals transmitted from
the base station during each slot period are set at the same value
(fixed value), and the total transmission electric powers of the
power control information transmitted during the first and second
power control information intervals also are set to be this fixed
value. Accordingly, as shown in FIG. 1C, for example, when the
power control information is simultaneously transmitted to the six
terminal stations, a transmission electric power of each power
control information becomes 1/6 of the fixed value. While the power
control information to the six users #0 to #5 are illustrated in
the state that they are simply added for simplicity in the example
shown in FIG. 1C, in actual practice, the power control information
that has been spread by using the code is added.
[0010] In the case of this digital cellular wireless communication
system, a modulation system and a coding rate of data transmitted
from the base station during the data interval is adaptively set in
response to the communication state between the base station and
the terminal station of the called party so that even the
arrangement in which the transmission electric power is fixed as
described above can cope with the change of the wireless
communication state between the base station and the terminal
station.
[0011] FIG. 2 (formed of FIGS. 2A and 2B drawn on two sheets of
drawings to permit a use of a suitably large-scale) is a block
diagram showing an example of an arrangement of a transmission
system of a base station for transmitting data to each terminal
station with the arrangement of the frame shown in FIGS. 1A and 1B,
for example. As shown in FIG. 2, there is provided a transmission
data generating section 10 which is a circuit for generating data
transmitted to a terminal station. A reception power management
section 11 is a circuit for generating power control information
transmitted to the terminal stations. Power control information to
individual terminal stations are supplied to separate terminals
(these terminals will hereinafter be, referred to as "power control
information input terminals") 12a to 12n. A pilot channel input
terminal 13 is a terminal to which pilot data is supplied from a
pilot data setting circuit (not shown).
[0012] Transmission data generated from the transmission data
generating section 10 is supplied to a data transmission processing
section 14, in which it is subjected to processings for
transmission such as transmission coding processing, modulation
processing and interleave processing. The data processed herein is
data located in the first to fourth data intervals of the slot
arrangement shown in FIGS. 1A and 1B, and the preamble data located
at the starting portion of the first data interval also is
processed. Since data allocated in the first to fourth data
intervals are fundamentally allocated to one terminal station by
the slot unit as earlier noted, during a period in which data of
one slot is processed, the coding system and the modulation system
suited for the terminal station for effecting a communication in
that slot are set by the data transmission processing section 14
and the transmission processing is executed.
[0013] The coding system and the modulation system suitable for the
terminal station are set based on bit rate information supplied
from a data rate control section 15 to the data transmission
processing section 14. To be concrete, when data which is to be
transmitted to a terminal station of which communication state
(receiving situation at the terminal station) is satisfactory is
transmitted, transmission data is coded by a multivalued modulation
such as a 16 QAM (16-quadrature amplitude modulation) and a high
coding rate and transmitted at a high throughput. When transmission
data which is to be transmitted to a terminal station whose
communication state is not satisfactory is transmitted,
transmission data is coded at a low coding rate and a QPSK
(quadrature phase shift keying)-modulated signal is spread or
transmitted a plurality of times and thereby transmitted at a low
throughput. Transmission data (I-channel data and Q-channel data)
processed by the data transmission processing section 14 are
supplied to a channel multiplex circuit 16.
[0014] Power control information supplied to the power control
information input terminals 12a to 12n are information prepared
individually at a plurality of terminal stations with which the
base station communicate in the same period, and individual
information is separately supplied to the power control information
input terminals 12a to 12n at every terminal station. Accordingly,
power control information are generated and supplied in response to
the number of terminal stations which communicate with the base
station in the same period. Power control information supplied to
one terminal station is 1-bit information per slot. Such 1-bit
information is used to instruct the corresponding terminal station
to increase transmission electric power or to decrease transmission
electric power.
[0015] Respective power control information obtained by the power
control information input terminals 12a to 12n are supplied to
repetitive processing sections 17a to 17n, in which each 1-bit data
is broken into four-times data, i.e., 4-bit data in which 1-bit
data is repeated four times. The 4-bit power control information
per slot are respectively supplied to respective spread processing
circuits 18a to 18n, in which they are spread and modulated into
data having a predetermined-time bit rate (bit rate of 32 times) by
using a predetermined code (e.g., Walsh Code) set at every terminal
station and thereby I-channel power control information and
Q-channel power control information are obtained. Since the 4-bit
data is spread by 32 times, there may be obtained data having a
data rate of 128 chips/slot.
[0016] The data spread and modulated by the respective spread
processing circuits 18a to 18n are supplied to a symbol multiplex
circuit 19, in which they are mixed into signals of one system. The
signals thus mixed are supplied to a variable gain setting circuit
20. The variable gain setting circuit 20 adjusts the gains of the
mixed power control information in a way that the gains may become
constant values. Specifically, in the case of this example, the
gain of the signal transmitted from the base station is a
predetermined constant value. The number of data which are
multiplexed by the symbol multiplex circuit 19 is changed in
response to the number of terminal stations which are communicating
with the base station at that time. Therefore, in response to the
number of data multiplexed by the symbol multiplex circuit 19, the
variable gain setting circuit 20 generates a signal having a
constant gain by adjusting the gain of the transmission signal. The
signals whose gain has been adjusted by the variable gain setting
circuit 20 are supplied to a channel multiplex circuit 16.
[0017] Pilot data obtained by a pilot channel input terminal 13 are
all null data and hence supplied to the channel multiplex circuit
16 as they are.
[0018] The channel multiplex circuit 16 multiplexes the respective
signals supplied thereto in a time-division manner such that the
slot arrangement shown in FIG. 1B may be obtained. The signals thus
multiplexed in a time-division manner by the channel multiplex
circuit 16 are supplied to a scramble processing circuit 21. The
scramble processing circuit 21 is supplied with spread codes of
both I-channel and Q-channel set for the base station from
terminals 22i, 22q and spreads data by using these spread codes.
The spread transmission signals of the I-channel and Q-channel are
supplied to a digital-to-analog (D/A) converter 23, in which they
are converted from digital data into analog data. The analog
transmission signal is supplied to a high-frequency
(radio-frequency) circuit 24, in which it is processed as a
high-frequency signal and thereby converted into a signal having a
predetermined transmission frequency channel. Then, the signal
having the converted transmission frequency is supplied to an
antenna 25, from which it is transmitted to each terminal station
by radio.
[0019] Since the transmission signal is transmitted from the base
station to each terminal station as described above, the base
station is able to individually communicate with respective
terminal stations at the unit of slots and is able to
simultaneously transmit the power control information for
instructing the transmission state of each terminal station to all
terminal stations at every slot. With respect to the wireless
transmission of up-link information from each terminal station to
the base station, the transmission electric power can properly be
set based on the power control information transmitted from the
base station and the base station can satisfactorily receive the
signal from each terminal station. With respect to the wireless
transmission of down-link information from the base station to each
terminal station, since the coding ratio and the modulation system
are set adaptively although the transmission power is fixed to the
constant value, the transmission signal can be satisfactorily
received by any terminal station. Specifically, if each terminal
station is a mobile station, then although a distance or a
communication state between each terminal station and the base
station is changed at any time, the above processing is effected on
the transmission signals of up-link information and down-link
information respectively, whereby the transmission processing
following the change of the distance or the communication state is
set adaptively so that wireless communication can constantly be
carried out satisfactorily.
[0020] Since the power control information multiplexed and
simultaneously transmitted are spread by an individual code at
every terminal station and transmitted, each terminal station can
receive only its own power control information by despreading the
received signal with the code allocated thereto, and hence each
terminal station can receive power control information
properly.
[0021] In the above transmission system, let it be assumed that
many users (terminal stations) want a connection at the same time.
At that time, since the traffic channel of down-link transmitted
from the base station is adapted to be shared by a plurality of
users, many users can be accommodated by decreasing a time
occupying ratio per user from a principle standpoint. With respect
to the traffic channel of up-link transmitted from the terminal
station, if the transmission electric power is decreased by
decreasing the transmission bit rate per user, then the time
occupying ratio can be decreased and hence the number of users can
be increased. If a communication between the base station and the
terminal station is data communication, then data transmission
periods are generated in a burst fashion and hence there occurs a
time zone in which there exists no transmission data even though
the connection is established. Accordingly, there frequently occurs
the situation in which one base station accommodates many terminal
stations whose connections are established between them and the
base station.
[0022] In the above transmission channel, if the number of users
having connections established increases, electric power
distributed to power control information (PC information) per
channel decreases. The reason for this is as follows:
[0023] An electric power distributed to power control information
per channel, for example, is expressed as:
[0024] [Electric power of PC information per channel
(connection)]=total transmission electric power/number of
connections
[0025] Further, in order that interference by a terminal station
accommodated in an adjacent cell comprised of another base station
can be controlled, (with respect to a terminal station which will
become a large interference source terminal station), power control
information should be transmitted to a terminal station which does
not transmit and receive data between it and its own station.
Consequently, since one terminal station monopolizes power control
information intervals of transmission signals of a plurality of
base stations, there should be provided more power control
information transmission channels than the number of the
accommodated terminal stations.
[0026] In this case, since [Electric power of PC information per
channel (connection)]=total transmission power/number of channels
in power control information interval and [number of channels in
power control information]>[number of connections] are
established, there are required more channels of the power control
information intervals.
[0027] If the number of accommodated connections increases
excessively, then the number of transmitted control information
increases in response thereto and transmission electric power of
control information distributed to one channel decreases. As a
result, when the terminal station receives power control
information, there arises a problem that the terminal station
cannot receive the power control information correctly because of a
shortage of electric power. If the terminal station becomes unable
to correctly receive the power control information, then a
receiving electric power at the reception side of the up-link
cannot be kept constant. As a consequence, it is unavoidable that a
quality of an up-link network line is degraded.
SUMMARY OF THE INVENTION
[0028] In view of the aforesaid aspect, it is an object of the
present invention to provide a communication system, a
communication method and a communication apparatus in which
information such as power control information that should be
individually instructed to respective terminal stations can
satisfactorily be transmitted to all terminal stations by simple
arrangement and simple processing.
[0029] According to an aspect of the present invention, there is
provided a communication system in which a base station and a
plurality of terminal stations communicate with each other by
radio. This communication system is comprised of a base station
which is comprised of data processing means for processing data
transmitted to each of the terminal stations, power control
information processing means for individually generating and
multiplexing power control information for instructing a
transmission electric power at each of the terminal stations and
adjusting transmission energy such that total transmission energy
of multiplexed power control information becomes substantially a
predetermined value if the total transmission energy of multiplexed
power control information is lower than a predetermined threshold
value and transmission processing means for multiplexing and
transmitting signals processed by the data processing means and the
multiplexed power control information processed by the power
control information processing means and each of the terminal
station which is comprised of measuring means for measuring a
receiving situation of a signal transmitted from the base station
and transmission processing means for transmitting information of
the receiving situation measured by the measuring means by an
electric power set based on power control information transmitted
from the transmission processing means of the base station.
[0030] According to other aspect of the present invention, there is
provided a communication method in which a base station and a
plurality of terminal stations communicate with each other by
radio. This communication method is comprised of the steps of
generating power control information for instructing an electric
power of a signal transmitted to the base station from the base
station to the plurality of terminal stations, adjusting
transmission energy such that total transmission energy of
multiplexed power control information becomes substantially a
predetermined value if the total transmission energy of the
multiplexed power control information is lower than a predetermined
threshold value, and transmitting the multiplexed power control
information from the base station to the plurality of terminal
stations.
[0031] According to a further aspect of the present invention,
there is provided a communication apparatus for communicating with
a plurality of terminal stations by radio which is comprised of
data processing means for processing data transmitted to each of
the terminal stations, power control information processing means
for individually generating power control information for
instructing transmission electric power at each of the terminal
stations and adjusting the transmission energy such that total
transmission energy of multiplexed power control information
becomes substantially a predetermined value if a total transmission
energy of the multiplexed power control information is lower than a
predetermined threshold value and transmission processing means for
multiplexing and transmitting the multiplexed power control
information processed by the data processing means and a signal
processed by the power control information processing means.
[0032] According to the present invention, when a base station and
a plurality of terminal stations are communicated with each other
by radio, control information for instructing an electric power of
a signal transmitted to the base station are multiplexed from the
base station to a plurality of terminals and a transmission energy
is adjusted such that the transmission energy becomes substantially
a predetermined value if a total transmission energy of the
multiplexed power control information is lower than the
predetermined value.
[0033] According to the present invention, the total transmission
energy of the power control information multiplexed and transmitted
from the base station is adjusted to become substantially the
predetermined value and the transmission state of the power control
information becomes satisfactory.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] FIGS. 1A to 1C are explanatory diagrams showing an example
of a frame format of down-link from a base station to a terminal
station and an example of an electric power distribution according
to the related art, respectively;
[0035] FIG. 2 (formed of FIGS. 2A and 2B drawn on two sheets of
drawings so as to permit a use of a suitably large-scale) is a
block diagram showing an example of an entire arrangement of a
transmission system of a base station according to the related
art;
[0036] FIG. 3 (formed of FIGS. 3A and 3B drawn on two sheets of
drawings so as to permit a use of a suitably large-scale) is a
block diagram showing an example of an overall arrangement of a
transmission system according to an embodiment of the present
invention;
[0037] FIGS. 4A and 4B are explanatory diagrams showing an example
of a part of a slot arrangement and an example of an electric power
distribution, respectively;
[0038] FIG. 5 is a flowchart to which reference will be made in
explaining how to control a signal power and the manner in which a
new channel is accepted;
[0039] FIGS. 6A and 6B are explanatory diagrams showing the manner
in which electric power of power control information is set (when a
new channel is accepted), respectively;
[0040] FIGS. 7A and 7B are explanatory diagrams showing the manner
in which electric power of power control information is set (when a
new channel is not accepted), respectively;
[0041] FIG. 8 is a flowchart to which reference will be made in
explaining power control and the manner in which a new channel is
accepted;
[0042] FIG. 9 is a flowchart to which reference will be made in
explaining power control and the manner in which a new channel is
accepted;
[0043] FIG. 10 is an explanatory diagram showing an example of a
transmission state according to an embodiment of the present
invention; and
[0044] FIG. 11 is a block diagram showing an example of an
arrangement of a terminal station according to an embodiment of the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0045] A communication system, a communication method and a
communication apparatus according to an embodiment of the present
invention will be described below with reference to FIGS. 3 to 11.
In FIGS. 3 to 11, elements and parts identical to those of FIGS. 1A
to 1C and FIG. 2 of the related art are identified with identical
reference numerals.
[0046] In this embodiment, the present invention is applied to a
communication system in which a CDMA system wireless signal is
transmitted between the base station and a plurality of terminal
stations in a bidirectional fashion. A fundamental slot arrangement
used when a down-link signal is transmitted from the base station
to each terminal station is the same as that shown in FIG. 1B as
the example of the related art. Specifically, under the condition
that the down-link transmission from the base station to each
terminal station is based on a TDMA (time division multiple access)
system with the frame arrangement shown in FIG. 1A and in which one
slot is allocated to one terminal station, the power control
information transmission interval is applied to an HDR (high data
rate) system in which signals to a plurality of terminal stations
and which had been spread by using different spread codes for every
terminal are multiplexed. In the case of this embodiment, the
transmission processing of the power control information within the
power control information transmission interval is executed by
processings different from those of the related art.
[0047] FIG. 3 (formed of FIGS. 3A and 3B drawn on two sheets of
drawings so as to permit a use of a suitably large-scale) is a
block diagram showing an example of an arrangement of a
transmission system of a base station according to this
embodiment.
[0048] As shown in FIG. 3, transmission data outputted from the
transmission data generating section 10 is supplied to the data
transmission processing section 14, in which it is processed in a
transmission processing fashion such as a coding processing, a
modulation processing and an interleave processing. When the
transmission data is generated from the transmission data
generating section 10, transmission data to a designated terminal
station is generated based on control data generated from a control
data generating section 28. The control data generating section 28
is adapted to generate control data under control of a channel
management section 27. The channel management section 27 is a
control section which manages the base station when the base
station communicates with a specific terminal station.
[0049] When the data transmission processing section 14 processes
transmission data, suitable factors such as a coding rate, a
modulation system and the number of repeated data are adaptively
set based on bit rate information supplied from the data rate
control section 15 to the data transmission processing section 14.
This data rate control section 15 is adapted to generate bit rate
information based on information concerning a communication state
transmitted from a terminal station, for example. Information
concerning communication states transmitted from respective
terminal stations is one which results from converting the
reception state (by way of example, a level difference called a CIR
between received electric power of a desired wave and received
electric power of an interference wave) of the signal into absolute
values based on a predetermined conversion table. The following
table 1 indicates an example of a relationship among coding rates,
modulation systems and the number of repeated data which are set
when the data transmission processing section 14 transmits data to
the corresponding terminal station based on the information
concerning the communication state. The table 1 sets 11 stages of
the communication states and shows examples of data rates.
1TABLE 1 Number Value of Modu- of Communica- Measured Coding lation
repe- tion state CIR value rate system titions Data rate 0 CIR <
-7[dB] 1/4 QPSK 16 0.03125 [bit/symbol] 1 -7 [dB] < 1/4 QPSK 8
0.0625 CIR < -8 [dB] [bit/symbol] 2 -6 [dB] < 1/4 QPSK 6
0.0833 CIR < -4 [dB] [bit/symbol] 3 -4 [dB] < 1/4 QPSK 4
0.1250 CIR < -3 [dB] [bit/symbol] 4 -3 [dB] < 1/4 QPSK 3
0.1667 CIR < -2 [dB] [bit/symbol] 5 -2 [dB] < 1/4 QPSK 2
0.2500 CIR < -1 [dB] [bit/symbol] 6 1 [dB] < 1/4 QPSK 1
0.5000 CIR < 3 [dB] [bit/symbol] 7 3 [dB] < 3/8 QPSK 1 0.7500
CIR < 5[dB] [bit/symbol] 8 5 [dB] < 1/2 QPSK 1 1.0000 CIR
< 9[dB] [bit/symbol] 9 9 [dB] < 1/2 8PSK 1 1.5000 CIR < 12
[dB] [bit/symbol] 10 12 [dB] < CIR 1/2 16QAM 1 2.0000
[bit/symbol]
[0050] In this manner, the data rates are adaptively set in
response to the communication states with the respective terminal
stations. Then, the transmission data (data of I-channel and data
of Q-channel) processed by the data transmission processing section
14 are supplied to the channel multiplex circuit 16.
[0051] Power control information supplied from the receiving power
management section 11 to the power control information input
terminals 12a to 12n is information individually prepared for a
plurality of terminal stations with which the base station
communicates in the same period. For every terminal station,
individual information is separately supplied to the input
terminals 12a to 12n. Power control information to one terminal
station is information of one bit per slot. Such one-bit
information is used to instruct the corresponding terminal station
such that the corresponding terminal station increases the
transmission electric power or decreases the transmission electric
power.
[0052] Respective power control information obtained by the input
terminals 12a to 12n is respectively supplied to power control
circuits 31a to 31n and thereby converted into multivalued signals.
FIG. 3 shows the case in which respective power control information
is converted by the power control circuits 31a to 31n into 2-bit
information (2-bit parallel data) per slot in which transmission
energy setting bit is added). This transmission energy setting bit
is generated based on the bit rate information supplied from the
data rate control section 15. To be concrete, when a transmission
setting bit rate to the destination terminal station of information
handled by the power control circuit of the system is higher than a
reference rate, a bit for setting low transmission energy is added
to the power control information based on the bit rate information
from the data rate control section 15, for example. When on the
other hand a transmission setting bit rate to the destination
terminal station of information handled by the power control
circuit of the system is lower than the reference rate, a bit for
setting high transmission energy is added to the power control
information.
[0053] The power control information with transmission energy
setting bits added by the respective power control circuits 31a to
31n are respectively supplied to other repetitive processing
sections 32a to 32n, in which they are converted into data of 4
times in which the same information is repeated 4 times per slot.
The power control information converted into the data of 4 times by
the respective repetitive processing sections 32a to 32n are
respectively supplied to separate spread processing circuits 33a to
33n, in which it is spread and modulated into data of predetermined
times (32 times) by using a predetermined code (e.g., Walsh Code)
set at every terminal station and thereby power control information
of I-channel and Q-channel are obtained. The data that had been
spread and modulated by the respective spread processing circuits
33a to 33n are supplied to a symbol multiplex circuit 34, in which
they are mixed as signals of one system. As a mixing processing
executed at that time, the mixing states are adaptively set based
on transmission energy set bit information. To be concrete, based
on the transmission energy setting bit, there are changed a mixing
ratio of power control information instructed to set low a
transmission energy and a mixing ratio instructed to set a high
transmission energy. Here, the mixing ratio is such one obtained
from a signal electric power (amplitude) standpoint.
[0054] FIGS. 4A and 4B are respectively diagrams showing examples
in which mixing ratios of power control information are set. As
shown in FIG. 4A, it is assumed that first and second power control
information intervals (RPC) are located ahead of and behind the
second pilot interval. Respective data intervals are assumed to be
464 chips, a pilot interval is assumed to be 96 chips, and the
first and second power control information intervals are
respectively assumed to be 64 chips.
[0055] Let it be assumed that power control information should
simultaneously be transmitted to six terminal stations of users #0
to #5 in the power control information interval, data to the users
#0 and #1 are power control information instructed to set a high
transmission energy and data with respect to the remaining users #2
to #5 are power control information instructed to set a low
transmission energy. At that time, as shown in FIG. 4B, power
control information of the users #0, #1 are mixed in such a manner
that they become a signal electric power about twice as large as
those of the power control information for other users #2 to #5.
When it is instructed that all mixed power control information is
mixed at a low mixing ratio or at a high mixing ratio, as a result,
the mixing ratios of information become equal to each other.
[0056] Referring back to FIG. 3, the power control information
mixed into the signal of one system by the symbol multiplex circuit
34 as described above is supplied to the variable gain setting
circuit 20. The variable gain setting circuit 20 adjusts the mixed
power control information such that the total gain of the mixed
power control information becomes substantially a constant value.
Specifically, in the case of this embodiment, the gain of the
signal transmitted from the base station is a predetermined
constant value and the variable gain setting circuit 20 adjusts the
gain in such a manner that the output from the symbol multiplex
circuit 34 may become constant electric power. Since the gain
adjustment is effected on the mixed power control information,
mixing ratios (electric power ratios) of amplitudes of power
control information for respective users are still those set when
power control information are mixed by the symbol multiplex circuit
34.
[0057] The variable gain setting circuit 20 adjusts power control
information under control of a total RPC power control section 26.
Bit rate information is supplied to the total RPC power control
section 26 from the data rate control section 15. The total RPC
power control section 26 controls power control information with
reference to bit rate information. The total RPC power control
section 26 communicates with the channel management section 27 and
manages the channel setting situation based on the transmitted
state of power control information. The situation in which the
variable gain setting circuit 20 sets the total gain of the power
control information under control of the total RPC power control
section 26 will be described later on. The signal whose gain has
been adjusted by the variable gain setting circuit 20 is supplied
to the channel multiplex circuit 16.
[0058] Pilot data obtained by the pilot channel input terminal 13
are all null data and therefore supplied to the channel multiplex
circuit 16 as they are.
[0059] The channel multiplex circuit 16 multiplexes supplied
signals in a time-division manner in a way that a predetermined
slot arrangement (slot arrangement shown in FIG. 1B) may be
obtained. The power control information supplied from the variable
gain setting circuit 20 is multiplexed in such a manner that data
of each slot unit is divided into data of first half and data of
second half and the data of first half is located in the first
power control information interval and the data of the second half
is located in the second power control information interval.
[0060] The signals thus multiplexed by the channel multiplex
circuit 16 in a time-division manner are supplied to the scramble
processing circuit 21. This scramble processing circuit 21 is
supplied with the spread codes of I-channel and Q-channel set for
this base station from the terminals 22i, 22q and spreads the
transmission signals by using these spread codes. The transmission
signals of the I-channel and Q-channel are supplied to the
digital-to-analog (D/A) converter 23, in which they are converted
into an analog transmission signal. The analog transmission signal
from the D/A converter 23 is supplied to the high-frequency (RF)
circuit 24, in which it is converted into a channel signal having a
predetermined transmission frequency by a high-frequency signal
processing. The converted signal having the above transmission
frequency is transmitted from the antenna 25 by radio and thereby
transmitted to each terminal station within the area by radio.
[0061] Next, the manner in which the transmission electric power of
the power control information is controlled and the channel is
managed based on the control of the transmission electric power of
the power control information within the above base station will be
described below. The control of the transmission electric power of
the power control information is executed by the variable gain
setting circuit 20 under control of the total RPC power control
section 26. The total RCP power control section 26 instructs the
channel management section 27 in channel management in response to
the state in which the power control information is being
transmitted at that time.
[0062] An example of control of the transmission electric power of
the power control information and channel management executed by
the total RPC power control section 26 will be described below with
reference to a flowchart of FIG. 5 (this example will be referred
to as an "example 1").
[0063] Referring to FIG. 5, and the following the start of
operation, at a step 101, the total RPC power control circuit 26
detects a total gain of mixed power control information outputted
from the symbol multiplex circuit 34. It is detected at the next
decision step 102 whether or not the detected gain is lower than a
previously-set threshold value Pth. For example, as shown in FIG.
6A, when a maximum power Pmax of a transmission electric power of
power control information is set, the threshold value Pth is set to
a value which is about 75% of the maximum power Pmax. The maximum
value Pmax corresponds to an output level of power control
information adjusted by the variable gain setting circuit 20 and is
substantially a maximum electric power which falls within a
tolerance range as signals transmitted from this base station,
namely the same level as data intervals, pilot intervals etc., for
example (or an electric power slightly lower than the maximum
electric power).
[0064] If the total gain is less than the threshold value Pth as
represented by a YES at the decision step 102, then control goes to
a step 103, whereat the gain of the signal (power control
information) is increased by the variable gain setting circuit 20
and is thereby set to the maximum power Pmax. Then, the
transmission signal is transmitted at that maximum power. For
example, when the total power judged at the step 102 is lower than
the threshold value Pth as shown in FIG. 6A, the total gain is
increased by the gain increase processing at the step 103 and is
thereby set to the maximum power Pmax and supplied to the circuit
of the succeeding stage (channel multiplex circuit 16).
[0065] After the step 103 had been executed, control goes to a step
104, whereat the total RPC power control section 26 informs the
channel management section 27 of the fact that a new channel can be
accepted. The state in which a new channel can be accepted is the
state in which when a request for starting a communication between
a new terminal station, which is not communicated at present, and
the base station is issued within a communication area for
communicating this base station by radio, for example, a
communication channel can be set between the base station and the
requested terminal station.
[0066] If on the other hand the total gain is not lower than the
threshold value Pth (i.e., the total gain is higher than the
threshold value Pth) as represented by a NO at the decision step
102, then control goes to the next decision step 105, whereat it is
determined whether or not the total gain obtained at that time
exceeds the maximum power Pmax. If the total gain does not exceed
the maximum power Pmax as represented by a NO at the decision step
105, control goes to a step 106, whereat the total gain is
increased by the variable gain setting circuit 20 and is thereby
set to the maximum power Pmax. Then, the transmission signal is
transmitted at the maximum power. For example, when the total power
judged at the step 105 is lower than the maximum power Pmax and is
higher than the threshold value Pth as shown in FIG. 7A, by the
gain increasing processing at the step 106, the total gain is
increased up to the maximum power Pmax as shown in FIG. 7B and
supplied to the circuit of the succeeding stage (channel multiplex
circuit 16).
[0067] If the total gain exceeds the maximum power Pmax as
represented by a YES at the decision step 105, then control goes to
a step 107, whereat a gain of a signal (power control information)
is decreased by the variable gain setting circuit 20 and is thereby
set to the maximum power Pmax. Then, the transmission signal is
transmitted at the maximum power.
[0068] After the gain of the power control information had been
adjusted at the step 106 or 107, control goes to a step 108,
whereat a channel which transmits power control information at the
largest power is selected from the current channels set for
communication with the terminal stations by the base station and
the selected channel is disconnected. As shown in FIG. 4B, for
example, when the signal for the two terminal stations of the users
#0, #1 uses the largest power as an example of an electric power
distribution of power control information, either the channel of
the signal for the user #0 or the channel of the signal for the
user #1 is disconnected.
[0069] This channel disconnection processing is executed by an
instruction from the total RPC power control section 26 to the
channel management section 27. This disconnection is a temporary
disconnection processing and the terminal station is being placed
in the standby mode until a channel is again allocated and a
communication is resumed.
[0070] When any one channel is disconnected at the step 108,
control goes to a step 109, whereat the total RPC power control
section 26 instructs the channel management section 27 of the state
in which the acceptance of a new channel should be rejected. The
state in which the acceptance of the new channel should be rejected
is the state in which when a request for starting a communication
between a new terminal station, which is not being communicated
with the base station, and the base station is issued within a
communication area in which a terminal station is communicated with
the base station by radio, the setting of communication channel to
such request is rejected.
[0071] In this manner, when the management of the total
transmission power of the power control information transmitted
from the base station and the processing for determining whether or
not the new channel is accepted are executed, the base station can
set the new channel while maintaining a minimum power state in
which the signal from the base station can be received by each
terminal station satisfactorily. In the case of this embodiment,
the predetermined value in which the total gain is lower than the
maximum power Pmax is set to the threshold value Pth. If the gain
exceeds the threshold value, then the acceptance of the new channel
is rejected so that a margin necessary for communication can be
maintained. Specifically, if the threshold value Pth is set to a
certain level lower than the maximum power Pmax, for example, then
even when the transmission electric power of the power control
information transmitted to the terminal station should be increased
due to the movement of the position of any terminal station which
is now being communicated with the base station, the transmission
electric power of the power control information to the
corresponding terminal station can be increased so that the
communication which is now being executed can be maintained
satisfactorily. If the transmission electric power of the power
control information should increase very frequently and the total
transmission electric power obtained before the power control
information is adjusted should exceed the maximum power Pmax, the
gain has to be decreased at the step 107.
[0072] Let us consider the situation in which the communication
area is set in the cell arrangement in which a plurality of base
stations are located. If the threshold value Pth is set to a
certain level lower than the maximum power Pmax to thereby provide
a margin, then when a terminal station, which is now being
communicating within the cell comprised of other base stations, is
moved into the cell of its own station, the channel for such new
terminal station can be set by using such margin, and hence a
switching of a communication between the base stations can be
executed smoothly. The processing for setting the channel in
accordance with the movement of the terminal station from other
cell can be regarded as the setting of new channel, and the setting
of the new channel can be accepted or rejected based on the
processing at the step 104 or 109.
[0073] In the example 1 shown in the flowchart of FIG. 5, it is
determined at the decision step 105 whether or not the total
transmission electric power obtained before the power control
information is adjusted exceeds the maximum power Pmax. If it is
determined at the decision step 105 that the above total
transmission electric power exceeds the maximum power Pmax, then
control goes to the step 107, whereat the gain is decreased and set
to the maximum power Pmax. The processing for decreasing the gain
at the step 107 may not always be executed. Specifically, as shown
in a flowchart of FIG. 8 (this example will be referred to as an
"example 2"), it is determined at the decision step 105 whether or
not the total transmission electric power obtained before the power
control information is adjusted exceeds the maximum power Pmax. If
it is determined at the decision step 105 that the total
transmission electric power exceeds the maximum power Pmax, then
control directly goes to a step 108, whereat a processing for
disconnecting a channel which uses a largest power to transmit
power control information may be executed. Other steps in the
flowchart of FIG. 8 are the same as those of the flowchart of the
example shown in FIG. 5.
[0074] As shown in the flowchart of FIG. 8, if the processing for
decreasing the gain is not executed when the total transmission
electric power exceeds the maximum power Pmax, there is then the
possibility that the total transmission electric power of the power
control information will exceed the prescribed maximum power Pmax a
little. So long as the power control processing shown in the
flowchart of FIG. 8 is executed properly, the total transmission
electric power of the power control information rarely exceeds the
maximum power Pmax. Even if the total transmission electric power
of the power control information exceeds the maximum power Pmax,
the level at which the total transmission electric power of the
power control information exceeds the maximum power Pmax is very
small, which is negligible in actual practice. In particular, when
a difference (margin) between the maximum power Pmax and the
threshold value Pth is large enough, the total transmission
electric power of the power control information never exceeds the
maximum power Pmax fundamentally. Hence, the processing in the
example 2 shown in the flowchart of FIG. 8 is suitable for the
management of channel.
[0075] While a disconnected channel is simply selected from the
channel (connection) which transmits the power control information
at the maximum power when the total transmission electric power
exceeds the threshold value as described above, the present
invention is not limited thereto, and some priorities may be set to
a disconnected channel or a connected channel.
[0076] An example shown in a flowchart of FIG. 9 (this example will
be referred to as an "example 3") shows an example in which under
the condition that priorities are set to terminal stations
connections), control of the transmission electric power of the
power control information and the channel management executed by
the total RPC power control section 26 are executed. Steps in the
flowchart of FIG. 9 will be described below. In the case of this
example, let it be assumed that priorities concerning communication
are set to respective terminal stations in advance. With respect to
the priority, although there may be set two priorities such as a
terminal station with a high priority and a terminal station with a
low priority, the present invention is not limited thereto and
priorities of about 5 stages may be set. Moreover, a priority set
to one terminal station is not limited to a fixed value of one kind
and a plurality of kinds of priorities may be set at every
connection in response to the contents of communication that has
been made at that time.
[0077] Under the condition that this priority is set to every
terminal station, steps in the flowchart of FIG. 9 are executed.
Referring to FIG. 9, and following the start of operation, at a
step 201, the total RPC power control section 26 detects the total
gain of the mixed power control information outputted from the
symbol multiplex circuit 34. Then, control goes to the next
decision step 202, whereat it is determined whether or not the
detected total gain is less than the previously-set threshold value
Pth.
[0078] If the detected total gain is less than the threshold value
Pth as represented by a YES at the decision step 202, control goes
to a step 203, whereat the variable gain setting circuit 20 sets
the total gain to the maximum power Pmax by increasing the gain of
the signal (power control information) and the power control
information is transmitted at the maximum power. After the
processing at this step 203 had been executed, control goes to a
step 204, whereat the total RPC power control section 26 informs
the channel management section 27 of the fact that the new channel
can be accepted. If the total gain is not less than the threshold
value Pth (i.e., higher than the threshold value Pth) as
represented by a NO at the decision step 202, then control goes to
the next decision step 205, whereat it is determined whether or not
the total gain obtained at that time exceeds the maximum power
Pmax. If the total gain is not in excess of the maximum power Pmax
as represented by a NO at the decision step 205, then control goes
to a step 206, whereat the variable gain setting circuit 20 sets
the total gain to the maximum power Pmax by increasing the gain of
the signal (power control information) and the power control
information is transmitted at the maximum power.
[0079] If on the other hand the total gain exceeds the maximum
power Pmax as represented by a YES at the decision step 205, then
control goes to a step 207, whereat the variable gain setting
circuit 20 sets the total gain to the maximum power Pmax by
decreasing the gain of the signal (power control information) and
the power control information is transmitted at the maximum
power.
[0080] After the gain had been adjusted at the step 206 or 207,
control goes to a step 208, whereat a channel with the lowest
priority and whose transmission electric power of power control
information is largest is judged from channels with the lowest
priority of channels set by the current base station to communicate
with terminal stations and one of the judged channels is
disconnected.
[0081] Control goes to the next decision step 209, whereat it is
determined whether or not a terminal station issues a channel
connection request with a terminal station with a high priority. If
a terminal station does not issue a channel connection request with
a terminal station with a high priority as represented by a NO at
the decision step 209, control goes to a step 210, whereat the
total RPC power control section 26 informs the channel management
portion 27 of the rejection of the acceptance of the new channel.
If on the other hand a terminal station issues a channel connection
request with a terminal station with a high priority as represented
by a YES at the decision step 209, control goes to a step 211,
whereat channels whose transmission electric power of power control
information is largest are judged from channels which are not being
set to terminal stations with priorities lower than that of the
terminal station which issued the connection request and one of the
judged channels is disconnected. Then, control goes to a step 212,
at which the channel is set to the terminal station with the high
priority judged at the step 209 by using the margin of the
disconnected channel.
[0082] In this manner, when the total transmission power of the
power control information exceeds the threshold value, since the
channel is set or disconnected based on the priority set at every
terminal station, a terminal station with a higher priority is
connected to the base station with a priority. Accordingly, a
channel can be rapidly set to a terminal station with a high
importance of communication by properly setting priorities in
response to an importance of communication.
[0083] While the channel is set or disconnected based on the
priorities under the condition that transmission electric powers of
individual power control information are changed adaptively in the
steps of the flowchart shown in FIG. 9, when the transmission
electric power of the power control information is made constant,
channels may be set or disconnected based on priorities of
respective terminal stations.
[0084] While priorities are given to terminals themselves in
advance as described above, each time the terminal station issues a
communication request, a priority may be set in response to the
contents of communication and a processing may be executed based on
the priority thus set.
[0085] Next, an example of a transmission state between the base
station in which a channel is set or disconnected as described
above and each terminal station will be described with reference to
FIG. 10. Let it be assumed that a service area la in which a base
station 1 communicates with terminal stations by radio is set as
shown in FIG. 10. Then, terminal stations 2, 3 and the base station
1 are communicating with each other by radio. The terminal stations
2, 3 which had received a down-link signal S1 from the base station
1 measure the receiving situations. For example, the terminal
stations 2, 3 judge the receiving states by measuring a received
electric field strength and an error rate of received data. The
respective terminal stations 2, 3 add data of judged reception
states to up-link signals S2, S3 which are to be transmitted to the
base station 1.
[0086] When receiving the up-link signals S2, S3 from the
respective terminal stations 2, 3, the base station 1 sets the
transmission processing state of the signal S1 transmitted from the
base station 1 on the basis of the data of the reception states
contained in the received signals S2, S3, i.e., "values of
communication states" on the table 1 and the situations under which
the base station 1 is receiving the signals S2, S3. To be concrete,
"Values of communication state"=8 is transmitted as the data of the
signal S1 reception state at the terminal 2 which is close to the
base station 1 so that the reception state better than the
reference level is judged. With respect to the reception situation
under which the base station 1 is receiving the signal S2 from the
terminal station 2, the satisfactory reception state is judged. At
that time, the base station 1 sets the coding rate and the
modulation system in response to the communication state=8 on the
table 1 as the processing in which the data transmission processing
section 14 processes data transmitted to the terminal station 2.
With respect to the power control information multiplexed to the
power control information interval and which is transmitted to the
terminal station 2, a mixing ratio at the symbol multiplex circuit
34 is set to be low.
[0087] Then, "values of communication state=1" is transmitted as
data indicative of the state in which the terminal station 3
distant from the base station 1 and which exists at the peripheral
portion of the area la is receiving the signal S1 so that the
situation in which the base station 1 is receiving the signal S3
from the terminal station 3 is judged as the poor reception state.
At that time, the base station 1 sets the coding rate and the
modulation system in response to the communication state=1 on the
table 1 as the processing in which the data transmission processing
section 14 processes the data transmitted to the terminal station
3. With respect to the power control information multiplexed to the
power control information interval and which is transmitted to the
terminal station 3, its mixing ratio at the symbol multiplex
circuit 34 is set to be high.
[0088] In this manner, the power control information are
transmitted to the respective terminal stations 2, 3, whereby the
respective terminal stations 2, 3 can receive power control
information satisfactorily. Accordingly, the respective terminal
stations 2, 3 can correctly judge the contents of the power control
information wherever the respective terminal stations 2, 3 are
located in the area 1a and can correctly set the transmission
electric power as they are instructed from the base station 1.
[0089] Data of power control information is 1-bit data for
increasing or decreasing a transmission electric power, and is set
based on whether an electric power at which the base station 1
receives the signals S2, S3 is higher than or lower than the
reference level. When receiving their own power control
information, the respective terminal stations 2, 3 execute the
processing for changing the transmission electric power to the
state instructed by that power control information (i.e.,
increasing or decreasing a transmission electric power). When the
power control information is transmitted from the base station 1 to
the terminal stations 2, 3, the base station 1 can receive the
signal at the receiving electric power of substantially constant
level regardless of the position at which the signal is transmitted
within the area la. Thus, the base station can avoid the reception
level from being fluctuated due to a distance between the base
station and the terminal station.
[0090] FIG. 11 schematically shows an example of a concrete
arrangement of the terminals stations 2, 3. First, the arrangement
of the transmission system of the terminal station will be
described. As shown in FIG. 11, transmission data applied to an
input terminal 91 is supplied to a data processing section 92, in
which it is converted into data of transmission slot arrangement.
Then, the data of the transmission slot arrangement is supplied to
a modem (modulator and demodulator) section 93, in which it is
modulated into transmission modulated data. This transmission
modulated data is supplied to a radio-frequency (high-frequency)
section 94, in which it is frequency-converted into a signal of a
predetermined transmission channel and transmitted from an antenna
95 by radio.
[0091] An arrangement of a receiving system of the terminal station
will be described below. A signal of a predetermined transmission
channel is received at the antenna 95 connected to the
radio-frequency section 94. Then, the received signal is modulated
by the modem section 93 and supplied to the data processing section
92, in which data is extracted from reception slot obtained by the
modulation and the extracted data is outputted from an output
terminal 96. A data processing apparatus such as a personal
computer is connected to the input terminal 91 and the output
terminal 96. Data-processing at the data processing section 92, the
modulation and demodulation processing at the modem section 93 and
the high-frequency processing at the radio-frequency section 94 are
executed under control of a controller 97.
[0092] With the above arrangement of the terminal station, the
judgment of the receiving situation of the down-link signal is
executed by the controller 97 when the controller 97 judges the
reception electric power at the radio-frequency section 94, the
data error rate at the data processing section 92, or the like. The
data of the judged receiving situation is added to transmission
data processed by the data processing section 92. The power control
information transmitted from the base station is extracted by the
data processing section 92 and supplied to the controller 97, and
the controller 97 sets a corresponding transmission electric power
by controlling an amplification factor of an amplifier provided
within the radio-frequency section 94, or the like.
[0093] While the transmission electric power of the power control
information is controlled in two stages as described above,
according to this embodiment, information concerning the
communication state are obtained from the terminal station in the
form of information of 11 stages so that the transmission electric
power (amplitude) of the control information may be more finely
controlled (converted into multivalued data). Examples of such
control are illustrated on the following table 2. An example 1 on
this table 2 shows an example of control of 2 stages of the
amplitude (electric power) (i.e., control corresponding to the
processing at the above embodiment), and examples 2 to 5 show
controls of 11 stages.
[0094] In the case of the examples 2 and 3, Outputs of the power
control circuits 31a to 31n should be 8-bit data. In the case of
the examples 4 and 5, outputs of the power control circuits 31a to
31n should be 6-bit data, respectively.
2TABLE 2 Value of Absolute communi- amplitude value of cation
Reported data information power state rate Example 1 Example 2
Example 3 Example 4 Example 5 0 0.03125 2 127 127 31 31
[bit/symbol] 1 0.0625 2 90 90 22 22 [bit/symbol] 2 0.0833 2 78 78
20 20 [bit/symbol] 3 0.1250 2 64 64 16 16 [bit/symbol] 4 0.1667 2
55 55 14 14 [bit/symbol] 5 0.02500 1 45 45 12 12 [bit/symbol] 6
0.5000 1 32 32 8 8 [bit/symbol] 7 0.7500 1 26 26 7 7 [bit/symbol] 8
1.000 1 23 20 6 5 [bit/symbol] 9 1.5000 1 19 13 5 4 [bit/symbol] 10
2.0000 1 16 10 4 3 [bit/symbol]
[0095] When the transmission electric power of the power control
information is controlled finely as described above, the power
control information can transmitted to each terminal station more
satisfactorily. In the case of the example 1 shown on the table 2,
since the step of the transmission electric power control is 6
[dB], the multivalued signals can easily be generated from the
power control circuits 31a to 31n by shifting the bits. The values
of the amplitudes shown on the table 2 show examples of relative
ratios between the reported data rates. Values substantially
similar to the ratios shown on the table 2 are suitable values and
are not limited to the values shown on the table 2.
[0096] While the communication states such as the encoding ratio,
the modulation system and the number of repetitions are determined
with reference to the table based on the table 1 from the values of
the measured communication states (CIR values in the above example)
in the processing shown on the above table 1, these communication
processing states may be obtained by a calculation processing using
a predetermined function from the measured communication state
values. With respect to the processing shown on the table 2, while
the absolute values of the amplitudes of the power control
information are determined with reference to the table based on the
table 2 from the reported data rates, the present invention is not
limited thereto and the absolute values of the amplitudes of the
power control information may be determined by a calculation
processing using a predetermined function from the reported data
rates.
[0097] While the present invention is applied to the slot
arrangement in which the power control information intervals are
located ahead of and behind the pilot interval as described above,
the present invention is not limited thereto and can be applied to
other slot arrangements. For example, a similar processing can be
applied to the case in which only one power control information
interval is located at one slot.
[0098] While the present invention is applied to the case in which
the power control information are individually transmitted from the
base station to the respective terminal stations as described
above, the present invention is not limited thereto and other
information that should be individually transmitted to the
respective terminal stations may be transmitted in a similar
processing. When the power control information is transmitted, the
power control information is not limited to the information which
instructs the increase or decrease of the transmission power
described in the above embodiment and may be information which
issues a more detailed instruction.
[0099] While the transmission energy of the power control
information is adaptively set at every terminal station as
described above, the present invention is not limited thereto. That
is, under the condition that the transmission energies of the power
control information to the respective terminal stations are set to
be equal, even when the number of channels is changed in accordance
with the number of terminal stations which communicate with the
base station, the total transmission energies are adjusted to
become equal to each other and the steps on the above flowchart may
be executed.
[0100] The numerical values described in the above embodiment show
examples by way of example and are not limited to the above
examples. When the transmission energy is set based on the maximum
power Pmax and the threshold value Pth, the transmission electric
power is not strictly matched with the maximum value Pmax and the
transmission electric power may fall within a certain range based
on the maximum value Pmax, for example.
[0101] While the coding rate, the modulation system and the number
of repeated data at the data transmission processing section 14
which is the data processing means are adaptively set based on the
bit rate information outputted from the data rate control section
15 and the processing of the power control information at the power
control circuits 31a to 31n which are the power control information
processing means are set adaptively in the concrete example of the
above embodiment, the present invention is not limited thereto, and
the adaptive setting at the data transmitting means and the
adaptive setting at the power control information processing means
may be executed based on other communication state information.
[0102] While the processing described in the above embodiment is
applied to the TDMA system in which one slot is allocated to one
connection as the frame arrangement and the data transmission
system called the HDR system in which only the power control
information transmission interval within each slot is multiplexed
by the CDMA system, the processing arrangement of the present
invention is not limited thereto and can be applied to other
transmission systems. For example, other intervals than the power
control information transmission interval may be multiplexed by the
CDMA system. Moreover, when signals other than the CDMA system are
transmitted by radio, the processing arrangement according to the
present invention can be applied.
[0103] According to the present invention, the total transmission
energy of the power control information multiplexed and transmitted
from the base station is adjusted so as to become substantially the
predetermined value, and hence the transmission state of the power
control information become satisfactory. Specifically, when the
total transmission energy of the power control information, for
example, is adjusted such that it becomes the allowable maximum
value, the transmission of individual power control information to
the respective terminal stations can be maintained in the most
satisfactory state at the very tolerance. Hence, it becomes
possible to reliably transmit the power control information to each
terminal station.
[0104] In this case, when the total transmission energy obtained
before the multiplexed power control information is adjusted is
higher than the predetermined threshold value, the setting of the
connection with the new terminal station is rejected. Hence, when
there is no margin in the transmission of the power control
information, the new channel can be prevented from being set and
the transmission energy of individual power control information can
be prevented from being decreased by the setting of the new
channel. Therefore, the satisfactory transmission state of the
power control information to individual terminal stations can be
maintained.
[0105] When the setting of the connection with the new terminal
station is rejected, if the terminal station which has the new
connection setting request has the terminal station having the high
priority, then the connection with the terminal station having the
low priority is forced to end and the connection with the terminal
station having the high priority is set. Thus, without degrading
the communication quality, the communication between the base
station and the terminal station can be set satisfactorily with the
priority based on the previously-determined priority.
[0106] In the above case, when the total transmission energy
obtained before the multiplexed power control information is
adjusted is higher than the predetermined threshold value, the
connection with any terminal station currently accommodated is
forced to end, whereby the communication with a certain margin can
constantly be made and the base station can satisfactorily
communicate with individual terminal stations. For example, when
the transmission energy of the power control information should be
increased between the base station and any one terminal station
which is being communicated with the base station, the
communication has the margin obtained by the above processing.
Therefore, even when the transmission energy is set to be large in
that system, the transmission energies of individual systems can be
set so as to fall within a proper range.
[0107] Further, when the connection with any terminal station which
is now being accommodated is forced to end, the transmission
energies of the power control information to the respective
terminal stations are adaptively and individually set at every
terminal station and multiplexed. Then, since the connection which
is forced to end is selected from the connections in which the
transmission energies are set to be large, it becomes possible to
maintain relatively large margin which is obtained by forcing the
connection to end.
[0108] Furthermore, when the connection with any terminal station
which is now being accommodated is forced to end, the connection
which is forced to end is selected from the connection whose
previously-determined priority is low. Therefore, when the high
priority is set in advance to the terminal station in which a
communication with a high importance is executed, the communication
with the high importance can be maintained in the satisfactory
state.
[0109] Having described a preferred embodiment of the invention
with reference to the accompanying drawings, it is to be understood
that the invention is not limited to that precise embodiment and
that various changes and modifications could be effected therein by
one skilled in the art without departing from the spirit or scope
of the invention as defined in the appended claims.
* * * * *