U.S. patent application number 12/092229 was filed with the patent office on 2010-05-06 for transmission and reception bandwidth setting method, mobile terminal, and base station in radio communication system defining a plurality of signal bandwidths.
This patent application is currently assigned to NTT DOCOMO, INC.. Invention is credited to Hiroyuki Atarashi, Kenichi Higuchi, Mamoru Sawahashi.
Application Number | 20100112951 12/092229 |
Document ID | / |
Family ID | 38005961 |
Filed Date | 2010-05-06 |
United States Patent
Application |
20100112951 |
Kind Code |
A9 |
Higuchi; Kenichi ; et
al. |
May 6, 2010 |
Transmission and Reception Bandwidth Setting Method, Mobile
Terminal, and Base Station in Radio Communication System Defining a
Plurality of Signal Bandwidths
Abstract
In a radio communication system defining a plurality of
bandwidths, mobile terminals of kinds respectively corresponding to
the plurality of bandwidths are accommodated in the system, and a
minimum transmission bandwidth of the plurality of bandwidths is
set as a transmission bandwidth of a downlink common channel. Or,
every mobile terminal accommodated in the radio communication
system is provided with a capability for processing a bandwidth
equal to or greater than a predetermined value, and equal to or
more than two transmission bandwidths that are equal to or less
than a predetermined value are set as a transmission bandwidth of a
downlink common channel. In the latter case, the mobile terminal
identifies a bandwidth of a received downlink common channel.
Inventors: |
Higuchi; Kenichi; (Kanagawa,
JP) ; Atarashi; Hiroyuki; (Kanagawa, JP) ;
Sawahashi; Mamoru; (Kanagawa, JP) |
Correspondence
Address: |
OSHA LIANG L.L.P.
TWO HOUSTON CENTER, 909 FANNIN, SUITE 3500
HOUSTON
TX
77010
US
|
Assignee: |
NTT DOCOMO, INC.
Tokyo
JP
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20080318527 A1 |
|
|
US 20090149129 A2 |
June 11, 2009 |
|
|
Family ID: |
38005961 |
Appl. No.: |
12/092229 |
Filed: |
October 31, 2006 |
PCT Filed: |
October 31, 2006 |
PCT NO: |
PCT/JP2006/322209 PCKC 00 |
371 Date: |
August 4, 2008 |
Current U.S.
Class: |
455/42 |
Current CPC
Class: |
H04L 5/003 20130101;
H04W 74/0816 20130101; H04L 5/0058 20130101; H04W 72/04 20130101;
H04B 1/707 20130101 |
Class at
Publication: |
455/42 |
International
Class: |
H04B 1/00 20060101
H04B001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 31, 2005 |
JP |
2005-317572 |
Claims
1. A method for setting a transmission and reception bandwidth in a
radio communication system defining a plurality of bandwidths,
comprising: accommodating mobile terminals of kinds respectively
corresponding to the plurality of bandwidths to the radio
communication system; and setting a minimum transmission bandwidth
of the plurality of bandwidths as a transmission bandwidth of a
downlink common channel.
2. A method for setting a transmission and reception bandwidth in a
radio communication system defining a plurality of bandwidths,
comprising: providing a processing capability of a bandwidth equal
to or greater than a predetermined value to every mobile terminal
accommodated in the radio communication system; and setting equal
to or greater than two transmission bandwidths equal to or less
than the predetermined value as transmission bandwidths of a
downlink common channel.
3. The transmission and reception band setting method as claimed in
claim 2, further comprising a step of identifying a bandwidth of a
received downlink common channel in the mobile terminal.
4. A method for setting a transmission and reception bandwidth in a
radio communication system defining a plurality of bandwidths,
comprising: accommodating mobile terminals of kinds respectively
corresponding to the plurality of bandwidths to the radio
communication system; and setting bandwidths respectively
corresponding to the plurality of bandwidths as bandwidths of a
pilot channel and as bandwidths of a data channel that are
transmitted from the mobile terminal using an uplink.
5. A method for setting a transmission and reception bandwidth in a
radio communication system defining a plurality of bandwidths,
comprising: accommodating mobile terminals of kinds respectively
corresponding to the plurality of bandwidths to the radio
communication system regarding transmission bandwidths of a data
channel transmitted using an uplink; and providing a processing
capability of a transmission bandwidth equal to or greater than a
predetermined value to every mobile terminal accommodated in the
radio communication system regarding transmission bandwidths of a
pilot channel transmitted using an uplink.
6. A method for setting a transmission and reception bandwidth in a
radio communication system defining a plurality of bandwidths,
comprising: providing capability for processing a transmission
bandwidth equal to or greater than a predetermined value, as a
transmission bandwidth of a pilot channel and a data channel for an
uplink, to every mobile terminal accommodated in the radio
communication system; and selecting a transmission bandwidth of the
pilot channel and the data channel within a range of a maximum
transmission bandwidth of the mobile terminal according to a
bandwidth used by the base station in the radio communication
system.
7. The transmission and reception bandwidth setting method as
claimed in claim 4, comprising: setting the transmission bandwidth
of the pilot channel to be wider than the transmission bandwidth of
the data channel in the uplink.
8. The transmission and reception bandwidth setting method as
claimed in 7, comprising: measuring a channel state on a frequency
axis using a received pilot channel in a base station in the radio
communication system to assign a transmission band of an uplink
data channel to the mobile terminal based on the channel state.
9. A method for setting a transmission and reception bandwidth in a
radio communication system defining a plurality of bandwidths,
comprising: setting a transmission bandwidth of an uplink collision
permissible channel transmitted from any mobile terminal in the
radio communication system to be a minimum transmission bandwidth
of the plurality of bandwidths.
10. A method for setting a transmission and reception bandwidth in
a radio communication system defining a plurality of bandwidths,
comprising: setting a transmission bandwidth of an uplink collision
permissible channel transmitted from any mobile terminal in the
radio communication system within a range of a predetermined
bandwidth greater than a minimum transmission bandwidth of the
plurality of bandwidths.
11. The transmission and reception bandwidth setting method as
claimed in claim 9, wherein the base station in the radio
communication system specifies a transmission band of an uplink
collision permissible channel transmitted by the mobile station
within a range of a bandwidth used by the base station.
12. The transmission and reception bandwidth setting method as
claimed in claim 9, wherein the base station in the radio
communication system predetermines a bandwidth used for receiving
an uplink collision permissible channel transmitted from the mobile
station within a range of a bandwidth used by the base station.
13. The transmission and reception bandwidth setting method as
claimed in claim 12, comprising: changing the bandwidth used for
receiving the uplink collision permissible channel within a range
of a bandwidth used by the base station as appropriate.
14. The transmission and reception bandwidth setting method as
claimed in claim 10, wherein the mobile station randomly changes
the band for transmitting the collision permissible channel within
a range of a bandwidth used by the base station which the mobile
station tries to access.
15. A mobile terminal apparatus used in a radio communication
system defining a plurality of bandwidths, comprising: a control
unit configured to set transmission bandwidths of an uplink pilot
channel and an uplink data channel that are transmitted to a base
station to perform channel generation control according to the
established transmission bandwidths.
16. The mobile terminal apparatus as claimed in claim 15, wherein
the control unit sets an uplink transmission bandwidth so as to
transmit the uplink pilot channel using a bandwidth wider than that
of the uplink data channel.
17. A mobile terminal apparatus used in a radio communication
system defining a plurality of bandwidths, comprising: a capability
for processing a bandwidth, of the plurality of bandwidths, equal
to or greater than a predetermined value; and a reception bandwidth
control unit configured to identify a bandwidth of a downlink
common channel received from any base station in the radio
communication system to control processes of a received signal
according to the identified bandwidth.
18. A base station used in a radio communication system defining a
plurality of bandwidths, comprising: a reception unit configured to
receive pilot channels of a first bandwidth from a plurality of
mobile terminals; a measurement unit configured to measure channel
states on a frequency axis based on the received pilot channels;
and a transmission band assignment unit configured to assign a
transmission band of a data channel using a second bandwidth
narrower than the first bandwidth to each mobile terminal based on
the measurement result.
19. The transmission and reception bandwidth setting method as
claimed in claim 5, comprising: setting the transmission bandwidth
of the pilot channel to be wider than the transmission bandwidth of
the data channel in the uplink.
20. The transmission and reception bandwidth setting method as
claimed in claim 6, comprising: setting the transmission bandwidth
of the pilot channel to be wider than the transmission bandwidth of
the data channel in the uplink.
Description
TECHNICAL FIELD
[0001] The present invention relates to a base station, a mobile
terminal, and a signal transmission and reception method used in a
radio communication system in which a plurality of different signal
bandwidths are defined.
BACKGROUND ART
[0002] As a successor of W-CDMA and HSDPA, a communication scheme
called Evolved UTRA (E-UTRA) is being studied. The E-UTRA is a
radio access scheme that supports a plurality of bandwidths in an
extensible manner, and that supports bandwidths from 1.25 MHz up to
20 MHz while maintaining compatibility with the existing 3G
scheme.
[0003] In the existing W-CDMA, a single bandwidth of 5 MHz is
supported in a same system, channels of uplink (from base station
to terminal) and downlink (terminal to base station) are allocated
so that data to be transferred is transmitted.
DISCLOSURE OF THE INVENTION
Problem to be Solved by the Invention
[0004] In contrast, in a system corresponding to E-UTRA, a
plurality of bandwidths are defined in a same system, and different
bandwidths are supported according to base stations or carriers.
That is, a state occurs in which bandwidths being used are
different according to systems (cells in a system of a same carrier
under certain circumstances) provided by each carrier. In such a
state, it is necessary that every mobile terminal can connect to
any base stations having different bandwidths.
[0005] In addition, a maximum transmission and reception bandwidth
that the mobile terminal can support at a minimum is an important
problem since it has an influence not only on implementation and
configuration of the terminal but also on configuration of a
physical channel corresponding to a synchronization channel (SCH)
or a broadcast channel (BCH).
[0006] In addition, it becomes important to set transmission
bandwidths of a collision permissible channel used when initially
accessing any base stations, from the mobile terminal, that use
different bandwidths, and a pilot channel and a data channel that
are transmitted from the mobile terminal to any base station.
[0007] Thus, an object of the present invention is to provide a
method for setting a proper bandwidth in a downlink and a method
for setting a proper bandwidth in an uplink in a radio
communication system in which a plurality of bandwidths are
defined.
[0008] In addition, an object is to provide configuration of the
mobile terminal and configuration of the base station according to
the bandwidth setting method.
Means for Solving the Problem
[0009] To realize the above-mentioned object, on the premise that a
plurality of bandwidths are defined in a radio communication
system, the present invention provides a reception bandwidth
setting method of a common channel in a downlink, a transmission
bandwidth setting method of a pilot channel and a data channel in
an uplink, the scheduling, and a transmission bandwidth setting
method of a collision permissible channel in an uplink, for each of
the following cases:
[0010] (1) A case in which mobile terminals of all kinds
corresponding to the plurality of bandwidths are prepared; and
[0011] (2) A case in which a maximum bandwidth equal to or greater
than a given value is set to every mobile terminal.
[0012] In a first aspect, as a first method for setting a bandwidth
of a common channel in a downlink, a method for setting a
transmission and reception bandwidth in a radio communication
system defining a plurality of bandwidths is provided, and the
method includes:
[0013] (a) accommodating mobile terminals of kinds respectively
corresponding to the plurality of bandwidths to the radio
communication system; and
[0014] (b) setting a minimum transmission bandwidth of the
plurality of bandwidths as a transmission bandwidth of a downlink
common channel.
[0015] As a second method, a method for setting a transmission and
reception bandwidth in a radio communication system defining a
plurality of bandwidths is provided, and the method includes:
[0016] (a) providing a processing capability of a bandwidth equal
to or greater than a predetermined value to every mobile terminal
accommodated in the radio communication system; and
[0017] (b) setting equal to or greater than two transmission
bandwidths equal to or less than the predetermined value as
transmission bandwidths of a downlink common channel.
[0018] In a second aspect, as a first method for setting bandwidths
of a pilot channel and a data channel in an uplink, a method for
setting a transmission and reception bandwidth in a radio
communication system defining a plurality of bandwidths is
provided, and the method includes:
[0019] (a) accommodating mobile terminals of kinds respectively
corresponding to the plurality of bandwidths to the radio
communication system; and
[0020] (b) setting bandwidths respectively corresponding to the
plurality of bandwidths as bandwidths of a pilot channel and as
bandwidths of a data channel that are transmitted from the mobile
terminal using an uplink.
[0021] As a second method, a method for setting a transmission and
reception bandwidth in a radio communication system defining a
plurality of bandwidths is provided, and the method includes:
[0022] (a) accommodating mobile terminals of kinds respectively
corresponding to the plurality of bandwidths to the radio
communication system regarding transmission bandwidths of a data
channel transmitted using an uplink; and
[0023] (b) providing a processing capability of a transmission
bandwidth equal to or greater than a predetermined value to every
mobile terminal accommodated in the radio communication system
regarding transmission bandwidths of a pilot channel transmitted
using an uplink.
[0024] As a third method, a method for setting a transmission and
reception bandwidth in a radio communication system defining a
plurality of bandwidths is provided, and the method includes:
[0025] (a) providing capability for processing a transmission
bandwidth equal to or greater than a predetermined value, as a
transmission bandwidth of a pilot channel and a data channel for an
uplink, to every mobile terminal accommodated in the radio
communication system; and
[0026] (b) selecting a transmission bandwidth of the pilot channel
and the data channel within a range of a maximum transmission
bandwidth of the mobile terminal according to a bandwidth used by
the base station in the radio communication system.
[0027] In the first to third methods, the transmission bandwidth of
the pilot channel is preferably set to be wider than the
transmission bandwidth of the data channel in the uplink.
[0028] In a third aspect, as a first method for setting a
transmission bandwidth of a collision permissible channel in an
uplink, a method for setting a transmission and reception bandwidth
in a radio communication system defining a plurality of bandwidths
is provided, and the method includes:
[0029] (a) setting a transmission bandwidth of an uplink collision
permissible channel transmitted from any mobile terminal in the
radio communication system to be a minimum transmission bandwidth
of the plurality of bandwidths.
[0030] As a second method, a method for setting a transmission and
reception bandwidth in a radio communication system defining a
plurality of bandwidths is provided, and the method includes:
[0031] (a) setting a transmission bandwidth of an uplink collision
permissible channel transmitted from any mobile terminal in the
radio communication system within a range of a predetermined
bandwidth greater than a minimum transmission bandwidth of the
plurality of bandwidths.
[0032] In any method, the base station in the radio communication
system may specify a transmission band of an uplink collision
permissible channel transmitted by the mobile station within a
range of a bandwidth used by the base station.
[0033] Or, the base station in the radio communication system may
predetermine a bandwidth used for receiving an uplink collision
permissible channel transmitted from the mobile station within a
range of a bandwidth used by the base station.
[0034] Or, the base station may randomly change the band for
transmitting the collision permissible channel within a range of a
bandwidth used by the base station which the mobile station tries
to access.
[0035] In a fourth aspect, a mobile terminal apparatus used in a
radio communication system defining a plurality of bandwidths is
provided. The mobile terminal apparatus includes:
[0036] (a) a control unit configured to set transmission bandwidths
of an uplink pilot channel and an uplink data channel that are
transmitted to a base station to perform channel generation control
according to the established transmission bandwidths.
[0037] In a preferred configuration example, the control unit sets
an uplink transmission bandwidth so as to transmit the uplink pilot
channel using a bandwidth wider than that of the uplink data
channel.
[0038] In a fifth aspect, a mobile terminal apparatus used in a
radio communication system defining a plurality of bandwidths
includes:
[0039] (a) a capability for processing a bandwidth, of the
plurality of bandwidths, equal to or greater than a predetermined
value; and
[0040] (b) a reception bandwidth control unit configured to
identify a bandwidth of a downlink common channel received from any
base station in the radio communication system to control processes
of a received signal according to the identified bandwidth.
[0041] In a sixth aspect, a base station used in a radio
communication system defining a plurality of bandwidths is
provided. The base station includes:
[0042] (a) a reception unit configured to receive pilot channels of
a first bandwidth from a plurality of mobile terminals;
[0043] (b) a measurement unit configured to measure channel states
on a frequency axis based on the received pilot channels; and
[0044] (c) a transmission band assignment unit configured to assign
a transmission band of a data channel using a second bandwidth
narrower than the first bandwidth to each mobile terminal based on
the measurement result.
EFFECT OF THE INVENTION
[0045] According to the present invention, a proper transmission
and reception bandwidth can be set in the downlink and the uplink
in a radio communication system defining a plurality of
bandwidths.
BRIEF DESCRIPTION OF THE DRAWINGS
[0046] FIG. 1 is a diagram for explaining a radio communication
system supporting a plurality of bandwidths on which the present
invention is predicated;
[0047] FIG. 2 is a diagram for showing a downlink bandwidth setting
method in a case for accommodating mobile terminals of kinds
corresponding to all bandwidths supported by the radio
communication system in the system shown in FIG. 1;
[0048] FIG. 3A is a diagram for showing a downlink bandwidth
setting method in a case for providing a capability for supporting
a maximum transmission bandwidth equal to or greater than a given
value to every mobile terminal in the system shown in FIG. 1;
[0049] FIG. 3B is a diagram for showing a downlink bandwidths
setting method in a case when providing a capability for supporting
a maximum transmission bandwidth equal to or greater than a given
value to every mobile terminal in the system shown in FIG. 1;
[0050] FIG. 4 is a diagram for showing an uplink bandwidth setting
method in a case when accommodating mobile terminals of kinds
corresponding to all bandwidths supported by the radio
communication system in the system shown in FIG. 1;
[0051] FIG. 5A is a diagram for showing an uplink bandwidth setting
method in a case when providing a capability for supporting a
maximum transmission bandwidth equal to or greater than a given
value to every mobile terminal in the system shown in FIG. 1;
[0052] FIG. 5B is a diagram for showing an uplink bandwidth setting
method in a case when providing a capability for supporting a
maximum transmission bandwidth equal to or greater than a given
value to every mobile terminal in the system shown in FIG. 1;
[0053] FIG. 5C is a diagram for showing an uplink bandwidth setting
method in a case when providing a capability for supporting a
maximum transmission bandwidth equal to or greater than a given
value to every mobile terminal in the system shown in FIG. 1;
[0054] FIG. 6A is a diagram showing an example for transmitting a
pilot channel using a bandwidth wider than that of a data channel
in an uplink;
[0055] FIG. 6B is a diagram showing an example for transmitting a
pilot channel using a bandwidth wider than that of a data channel
in an uplink;
[0056] FIG. 7A is a diagram for explaining a method for performing
uplink scheduling based on a received pilot channel in a base
station;
[0057] FIG. 7B is a diagram for explaining a method for performing
uplink scheduling based on a received pilot channel in a base
station;
[0058] FIG. 7C is a diagram for explaining a method for performing
uplink scheduling based on a received pilot channel in a base
station;
[0059] FIG. 8 is a block diagram showing an example of a
transmitter configuration of a mobile terminal used by a radio
communication system supporting a plurality of bandwidths;
[0060] FIG. 9 is a block diagram showing an example of a receiver
configuration of a mobile terminal used by a radio communication
system supporting a plurality of bandwidths;
[0061] FIG. 10 is a block diagram showing a configuration example
of a base station in a case when performing uplink scheduling;
[0062] FIG. 11A is a diagram for explaining a method for
transmitting a collision permissible channel in an uplink;
[0063] FIG. 11B is a diagram for explaining a method for
transmitting a collision permissible channel in an uplink.
DESCRIPTION OF REFERENCE SIGNS
[0064] 10 mobile terminal [0065] 10a transmitter of the mobile
terminal [0066] 10b receiver of the mobile terminal [0067] 21 pilot
channel/data channel transmission bandwidth control unit of the
mobile terminal [0068] 50 reception bandwidth control unit of the
mobile terminal [0069] 60 base station [0070] 61 pilot channel
reception unit [0071] 62 channel state measurement unit [0072] 63
data channel transmission band assignment unit
PREFERRED EMBODIMENTS FOR CARRYING OUT THE INVENTION
[0073] Before describing the preferred embodiments, an overview of
the radio communication system on which the present invention is
based is described with reference to FIG. 1. The present invention
is predicated on a system in which a plurality of bandwidths are
defined in a same system. Therefore, transmission bandwidths of the
downlink and reception bandwidths of the uplink are different
according to base stations (or carriers). Every mobile terminal
should connect to any of base stations having different bandwidths
while moving.
[0074] In FIG. 1, the radio communication system includes base
stations 1-5 using different transmission bandwidths that are 20
MHz, 10 MHz, 5 MHz, 2.5 MHz and 1.25 MHz, for example. The
transmission frequency bandwidth used by each base station is
determined based on a frequency spectrum that each carrier can use.
Assuming that there are a plurality of bandwidths in such a same
system, in order to connect the mobile terminal 10 to any base
station, following items should be considered:
[0075] (1) Transmission of a common channel from a base station to
a mobile station in the downlink, and setting of a maximum
bandwidth of a mobile terminal 10;
[0076] (2) Transmission of a pilot channel and a data channel in
the uplink, and scheduling for them; and
[0077] (3) Transmission of collision permissible type channel in
the uplink. In the following, each of them are described.
[0078] <Transmission of Common Channel and Setting of Maximum
Bandwidth of the Mobile Terminal in the Downlink>
[0079] In the downlink of the radio communication system that
supports a plurality of transmission bandwidths, following two
methods can be considered as methods for setting bandwidths such
that the mobile terminal 10 can receive the common (physical)
channel from any base station. That are methods of:
[0080] (i) Preparing mobile terminals 10 of all kinds that
correspond to all of the bandwidths supported by the system, and
transmitting the downlink common (physical) channel using a minimum
bandwidth in the plurality of bandwidths supported by the system,
or
[0081] (ii) Setting a maximum bandwidth that every mobile terminal
10 should support as a minimum value, and transmitting the downlink
common (physical) channel using equal to or more than two
bandwidths that are equal to or less than the bandwidth of the
minimum value.
[0082] In the first method, for example, as shown in FIG. 1, when
the radio communication system supports five kinds of bandwidths,
five kinds of mobile terminals 10 that are a mobile terminal
supporting 1.25 MHz, a mobile terminal supporting 2.5 MHz, a mobile
terminal supporting 5 MHz, a mobile terminal supporting 10 MHz, and
a mobile terminal supporting 20 MHz are prepared, and they are
accommodated in the system.
[0083] In this case, since there is a mobile terminal 10 that can
receive only a signal of the signal bandwidth of 1.25 MHz, every
base station transmits a physical channel corresponding to a common
channel such as the synchronization channel (SCH) and the broadcast
channel (BCH) using a bandwidth of 1.25 MHz that is the smallest
bandwidth in the system irrespective of a bandwidth of the system
used in the cell.
[0084] In the second method, every mobile terminal has at least a
given maximum bandwidth. For example, every mobile terminal 10 is
designed to have a bandwidth of 5 MHz at least, or a bandwidth of
10 MHz at least.
[0085] According to this method, since every mobile terminal 10
that is accommodated in the system can support a maximum bandwidth
that is equal to or greater than a given value, it is only
necessary that the base station transmits the common channel using
a bandwidth equal to or less than the given maximum bandwidth in a
plurality of bandwidths defined in the system.
[0086] FIG. 2 is a diagram for explaining the first method (i) for
setting the downlink signal bandwidth in more detail. As shown in
the left side of FIG. 2, the radio communication system supports
five different kinds of system bandwidths depending on cells and
accommodates mobile terminals 10 of kinds that correspond to all
bandwidths. In this case, as shown in the right side of FIG. 2, the
transmission bandwidth of the common channel (SCH, BCH, and the
like) in each cell is 1.25 MHz in accordance with the smallest
bandwidth in the system irrespective of system bandwidth that the
cell can use.
[0087] According to this scheme, every kind of mobile terminal 10
can receive a common channel from a base station even though the
mobile terminal 10 moves to any cell.
[0088] In addition, since every base station transmits the
synchronization channel or the broadcast channel using the same
minimum signal bandwidth, methods of demodulation and decoding of
the common channel in the mobile terminal 10 becomes simple and
unified. In addition, since terminals of the existing W-CDMA scheme
and UMTS (W-CDMA)/GMS dual mode terminals have a 5 MHz downlink
physical channel receiving capability, there is an advantage of
commonality between the existing systems and the new system so that
it can be considered that dual mode of both systems can be easily
realized.
[0089] FIGS. 3A and 3B are diagrams for describing the second
method (ii) for setting the downlink signal bandwidth in more
detail. In the example of FIG. 3A, the maximum bandwidth that every
mobile terminal 10 should support at the minimum is set to be 5
MHz, and in the example of FIG. 3B, it is set to be 10 MHz.
[0090] In FIG. 3A, the left side indicates five kinds of bandwidths
that the system supports, and the right side indicates signal
bandwidths used for each base station to transmit the common
channel when every mobile terminal 10 has the maximum bandwidth of
5 MHz at the minimum. A base station (carrier) that uses a
bandwidth of 1.25 MHz transmits the common channel using the
bandwidth. A base station that uses a bandwidth of 2.5 MHz
transmits the common channel using 2.5 MHz or 1.25 MHz. Since the
mobile terminal 10 supports a bandwidth of 5 MHz at the minimum,
the mobile terminal 10 can receive the common channel from the base
station in either case.
[0091] Base stations using bandwidths of 5 MHz, 10 MHz and 20 MHz
transmit the common channel using 5 MHz in accordance with the
maximum bandwidth of the minimum value kept in every mobile
terminal 10. Since the common channel is transmitted using the
bandwidth of 5 MHz, high diversity effect can be obtained.
Therefore, reception quality when the mobile terminal 10 receives
the channel. In addition, dual mode with the existing W-CDMA can be
easily realized.
[0092] In the system of FIG. 3A, since the downlink common channel
is transmitted using 5 MHz or 1.25 MHz (or 2.5 MHz) according to
the base station, it is necessary to set more than one kind of
format of the common channel in the radio communication system. In
addition, it is necessary to detect and identify the bandwidth of
the common channel before demodulating and decoding SCH or BCH in
the mobile terminal 10. As a method for realizing this, there is a
method in which the base station reports information on the
bandwidth used for transmitting the common channel such as SCH and
BCH to the mobile terminal 10 beforehand by separately preparing a
control channel of 1.25 MHz, for example. Alternatively, a
configuration may be adopted in which when information of a band of
1.25 MHz in SCH or BCH is decoded and when it is recognized that
there is SCH or BCH of 5 MHz band based on the decoded information,
information of the band of 5 MHz is decoded again. Alternatively, a
configuration may be adopted in which the mobile terminal 10
estimates the parameter (bandwidth) using a blind method.
[0093] As to FIG. 3B, although FIG. 3B is similar to FIG. 3A, since
every mobile terminal 10 supports the maximum reception bandwidth
of 10 MHz at the minimum, a base station using a 5 MHz bandwidth
transmits the common channel using 5 MHz, and a base station using
a bandwidth of 10 MHz or 20 MHz transmits the common channel using
10 MHz that is the reception bandwidth of the minimum value of the
mobile terminal 10. Also in this case, the mobile terminal 10 has a
function of identifying the bandwidth of the common channel. That
is, in the same way as the example of FIG. 3A, the bandwidth of the
downlink common channel is identified by reporting bandwidth
information using a control channel of the lowest bandwidth (1.25
MHz, for example) supported by the system or by estimating
bandwidth using the blind method.
[0094] According to the method of FIG. 3, since every mobile
terminal 10 has the maximum reception bandwidth equal to or greater
than a given level, kinds and performance of mobile terminals 10
can be unified. In addition, improvement of reception quality due
to diversity effect can be expected.
[0095] By the way, in the examples shown in FIGS. 3A and 3B,
although SCH and BCH are transmitted using a same bandwidth, it is
not necessary to use the same bandwidth. For example, a base
station having a bandwidth of 2.5 MHz may transmit BCH using 2.5
MHz and transmit SCH using 1.25 MHz.
[0096] <Transmission Bandwidth and Transmission Schedule in
Uplink>
[0097] Next, transmission bandwidths of a pilot channel and a data
channel in the uplink, and the scheduling are described. As methods
for setting bandwidths for transmitting a pilot channel and a data
channel to any base station by the mobile terminal 10 in the uplink
of the radio communication system, there are the following two
methods like the case of the downlink common channel. That is:
[0098] (i) Preparing mobile terminals 10 of kinds corresponding to
all bandwidths supported by the system; or
[0099] (ii) Setting a maximum bandwidth that every mobile terminal
10 should support as a minimum value.
[0100] FIG. 4 shows a method for setting transmission bandwidth of
the uplink when the first method is adopted, that is, when mobile
terminals 10 of kinds corresponding to all bandwidths are
accommodated. The left side shows five kinds of bandwidths
supported by the radio communication system. The center section
shows maximum bandwidths, for transmitting a data channel from the
mobile terminal 10, that can be processed in the corresponding
cell. The right side shows transmission bandwidths of a pilot
channel from the mobile terminal 10 that can be processed in the
corresponding cell.
[0101] Since all kinds of mobile terminals 10 corresponding to a
plurality of kinds of maximum transmission bandwidths from 1.25 MHz
to 20 MHz are accommodated in the uplink, each mobile terminal 10
transmits, to any base station, within a range of a bandwidth
supported by the own mobile terminal, a pilot signal and a data
signal according to a system bandwidth supported by the base
station. For example, in a cell using a bandwidth of 2.5 MHz, a
mobile terminal 10 supporting a bandwidth of 5 MHz transmits the
pilot signal or the data signal using 2.5 MHz of the 5 MHz. When
the mobile terminal 10 moves to a cell using a bandwidth equal to
or greater than 5 MHz, the mobile terminal 10 transmits the pilot
signal or the data signal using a bandwidth of 5 MHz.
[0102] By the way, it is desirable that the mobile terminal 10 that
supports a bandwidth equal to or greater than 2.5 MHz transmits a
pilot channel using a bandwidth greater than that used for a data
channel. For example, as shown in FIG. 6A, the pilot channel is
transmitted using 2.5 MHz, and the data channel is transmitted
using 1.25 MHz.
Alternatively, as shown in FIG. 6B, the pilot channel is
transmitted using 5 MHz, and the data channel is transmitted using
2.5 MHz. By adopting such a configuration, the base station side
can perform scheduling according to a channel state (SIR and the
like) on the frequency axis using the received pilot channel.
Details of the scheduling using the pilot channel are described
later.
[0103] FIGS. 5A-5C show a method for setting the uplink
transmission bandwidth when the second method is adopted, that is,
when a maximum transmission bandwidth as minimum value is set for
every mobile terminal 10. In the example shown in FIG. 5A, although
every mobile terminal 10 supports 5 MHz at the minimum for
transmitting the pilot channel, maximum transmission bandwidths for
the data channel (and control channel) are set in accordance with
all kinds of bandwidths. On the other hand, in the example of FIG.
5B, every mobile terminal 10 supports a transmission bandwidth of 5
MHz at the minimum for both of the pilot channel and the data
channel. In the example of FIG. 5C, every mobile terminal 10
supports a transmission bandwidth of 10 MHz at the minimum for both
of the pilot channel and the data channel.
[0104] In the example of FIG. 5A, as to transmission of a data
channel, mobile terminals 10 of kinds corresponding to all
bandwidths supported by the system are prepared. But, as to
transmission of pilot channel, the maximum bandwidth of at least 5
MHz is kept for every mobile terminal 10. For example, as shown in
FIG. 6B, in a cell that supports a bandwidth equal to or greater
than 5 MHz, the mobile terminal 10 transmits a pilot channel using
5 MHz, and transmits a data channel using a bandwidth of 2.5 MHz
according to scheduling from the base station. In a cell supporting
2.5 MHz, as shown in FIG. 6A, a pilot channel is transmitted using
2.5 MHz of the 5 MHz, and a data channel is transmitted using a
bandwidth of 1.25 MHz according to scheduling of the base
station.
[0105] FIGS. 7A-7C are diagrams for describing scheduling using the
pilot channel. It is assumed that every mobile terminal 10 can use
a maximum transmission bandwidth of 5 MHz at the minimum for
transmitting the pilot channel. As shown in FIG. 7A, each of mobile
terminals of users 1-4 transmits a pilot channel using a bandwidth
of 5 MHz in a cell (step 1).
[0106] As shown in FIG. 7B, when the base station receives pilot
signals from the users 1-4, the base station measures channel
states of the mobile terminals 10 of each user on the frequency
axis (step 2). For example, the pilot channel from the mobile
terminal of the user 1 indicates a good channel state in the first
half part of the 5 MHz bandwidth. The pilot channel of the user 2
indicates the peak in a side a little lower than the center of the
5 MHz bandwidth. The pilot channel of the user 3 indicates a good
channel state in the latter half part of the 5 MHz bandwidth.
[0107] As shown in FIG. 7C, based on the measured channel states,
the base station assigns data channels of bandwidths each narrower
than the pilot channel on the frequency axis to the users 1, 2 and
3. In the example of FIG. 7C, the base station assigns first 1.25
MHz of the 5 MHz bandwidth to the user 1, assigns next 1.25 MHz to
the user 2, and assigns the latter half 2.5 MHz to the user 3. At
this time, there is no assignment for user 4. The bandwidth to be
assigned for transmission of the data channel for each user can be
determined based on information (capability) of a maximum
transmission bandwidth of terminal transmitted from the mobile
terminal. The mobile terminal of each user transmits the data
channel using a band narrower than that of the pilot channel based
on an assignment instruction from the base station (step 3).
[0108] Accordingly, even though a mobile terminal has low
capability for transmitting the data channel, a predetermined
maximum transmission bandwidth (5 MHz, for example) is kept for
every mobile terminal 10 as to transmission of the pilot channel,
and the bandwidth for transmitting the data channel is set to be
smaller than that so that efficient scheduling according to channel
states becomes possible. As a result, throughput of the system
improves.
[0109] Returning to FIG. 5B, in this example, every mobile terminal
10 has a maximum transmission bandwidth of 5 MHz at least for both
of the pilot channel and the data channel. In the example of FIG.
5C, every mobile terminal 10 has a maximum transmission bandwidth
of 10 MHz at least for both of the pilot channel and the data
channel. In either case, like the case of FIG. 5A, the base station
can perform transmission scheduling of the data channels in bands
each narrower than that of the pilot channel based on received
pilot channels, so that throughput of the system can be
improved.
[0110] FIG. 8 is a block diagram showing a transmitter 10a of the
mobile terminal 10. A baseband unit of the transmitter 10a
includes, as a data channel processing system, a channel coding
unit 21 for coding transmission data that is input, a data
modulation unit 22 and a band limit filter 23, and includes, as a
pilot channel processing system, a pilot signal generation unit 24
and a band limit filter 25.
[0111] When uplink scheduling is performed in the base station like
the case shown in FIGS. 7A-7C, the mobile terminal 10 transmits a
pilot channel and a data channel of different bandwidths. In this
case, a pilot channel/data channel transmission bandwidth control
unit 31 controls the transmission bandwidths of the pilot channel
and the data channel within a range of the maximum reception
bandwidth of the base station that is reported by a downlink
control channel. As methods for control, there are a method of
setting transmission bandwidth of the data channel based on the
transmission bandwidth specified by the scheduling from the base
station using the method shown in FIGS. 7A-7C, and a method of
setting transmission bandwidths of the pilot channel and the data
channel selected by the control unit 31 itself.
[0112] Each of a pilot channel signal and a data channel signal on
which baseband processing has been performed is received by a D/A
converter 26 of the IF unit so as to pass through an IF filter 27.
When transmission bandwidths of the pilot and the data are
different, the bandwidth of the IF filter 27 is adjusted to the
transmission bandwidth of the pilot. Output of the IF filter 27 is
received by an up converter 28 of the RF unit so as to be converted
to a RF frequency according to an uplink transmission frequency
band that is set. By the way, a part of this function may be
performed by the baseband unit. The RF-converted signal passes
through the RF filter 29. When transmission bandwidths of the pilot
and the data are different, the bandwidth of the RF filter 27 is
adjusted to the transmission bandwidth of the pilot. Output of the
RF filter 27 is amplified by a power amplifier 30. Since
transmission power of the data channel is larger than that of the
pilot channel, the size of the power amplifier is determined
according to the transmission bandwidth of the data channel. The
amplified transmission signal is transmitted from the transmission
antenna.
[0113] FIG. 9 is a block diagram of a receiver 10b of the mobile
terminal 10. A RF signal received by the antenna passes through a
low noise amplifier (LNA) 41 and a RF filter 42, and is converted
into an intermediate frequency by a down converter 43 in the RF
unit. Next, in the IF unit, the signal passes through an IF filter
44 and is converted into an analog signal by a D/A converter 45. In
the baseband unit, the signal is filtered, demodulated and decoded
by a band limit filter 46, a data demodulation unit 47 and a
channel decoding unit 48. When the maximum reception bandwidth of 5
MHz is kept in every mobile terminal 10 at the minimum, dual mode
operation with the existing W-CDMA is easy for the RF filter 42 and
the IF filter 44.
[0114] In addition, when a maximum reception bandwidth equal to or
greater than a given value is kept for the mobile terminal 10,
since a bandwidth of the common channel received from a base
station is different according to a bandwidth used in the cell, it
is necessary to perform filtering, demodulation and decoding
processes in accordance with the bandwidth. A reception bandwidth
control unit 50 supplies a control signal for performing settings
according to the reception bandwidth to the band limit filter 46,
the data demodulation unit 47 and the channel decoding unit 48. The
reception bandwidth control unit 50 performs control based on
bandwidth information reported by a downlink control channel, for
example. Alternatively, although not shown in the diagram, a
parameter estimation unit may be provided to estimate the
bandwidth.
[0115] FIG. 10 is a block diagram showing a configuration example
of a base station used in a radio communication system that
supports a plurality of bandwidth. The base station 60 includes a
pilot signal reception unit 61 for receiving a pilot signal of a
first bandwidth from the mobile terminal 10, a channel measurement
unit 62 for measuring a channel state of each mobile terminal on
the frequency axis based on the received pilot channel, and a data
channel transmission bandwidth assignment unit 63 for assigning a
transmission band of a data channel using a second bandwidth that
is narrower than the first bandwidth to each of mobile terminals
based on the measurement result.
[0116] This configuration of the base station is useful when a
configuration is adopted in which every mobile terminal has a
maximum transmission bandwidth equal to or greater than a given
value. This is because uplink scheduling can be performed based on
the pilot channel as shown in FIG. 7.
[0117] <Setting of Collision Permissible Channel in the
Uplink>
[0118] FIGS. 11A and 11B are diagrams for describing a transmission
method of an uplink collision permissible channel when the mobile
terminal 10 accesses a base station initially in a radio
communication system supporting a plurality of bandwidths. When the
mobile terminal initially accesses the base station, the mobile
terminal transmits a collision permissible channel such as a
reservation channel and a random access channel based on the
premise of the possibility of collision. When the radio
communication system supports a plurality of bandwidth, it is
necessary to consider the transmission method of the collision
permissible channel since bandwidths used by base stations and
capabilities of mobile terminals are different.
[0119] FIG. 11A shows a method for setting a minimum bandwidth
(1.25 MHz, for example) supported by the radio communication system
to be a bandwidth of the collision permissible channel. Since the
bandwidth of the collision permissible channel is uniformly
determined, every base station receives the collision permissible
channel using a same method, so that system design becomes easy.
This method may be applied to a case for accommodating mobile
terminals of kinds supporting all bandwidths supported by the
system, and also applied to a case for setting a maximum
transmission bandwidth equal to or greater than a minimum value for
every mobile terminal.
[0120] In the example of FIG. 11A, the base station can use a
bandwidth of 20 MHz. When accessing the base station initially,
every mobile terminal (A, B, C) transmits the collision permissible
channel using 1.25 MHz that is the minimum bandwidth of the
system.
[0121] As a method for transmitting the collision permissible
channel, there are methods of:
[0122] (1) Specifying, to the mobile terminal, using a control
channel and the like, a band by which transmission of the collision
permissible channel is allowed in the whole bandwidth used by the
base station;
[0123] (2) In the base station, determining beforehand a band, in
the whole bandwidth, by which transmission of the collision
permissible channel is allowed;
[0124] (3) In the mobile terminal side, randomly determining a band
for transmitting the collision permissible channel within a range
of the bandwidth used by the base station which the mobile station
tries to access.
[0125] In the first method, the base station assigns bandwidths,
that are unoccupied as a result of scheduling, for example, to the
terminals A, B and C as transmission bandwidths of the collision
permissible channel.
[0126] In the second method, a reception permissible bandwidth of
the uplink collision channel is determined beforehand as shown in
the arrows of both directions so that reception is performed within
the band. In this case, a configuration may be adopted in which the
reception permissible bandwidth of the uplink collision permissible
channel is shifted to another band on the frequency axis every
predetermined time within a range of the whole bandwidth used by
the base station. Accordingly, while the collision permissible
channel is received within a range of a given narrow band, wide
band effect can be obtained.
[0127] In the third method, the mobile terminal randomly determines
the transmission band of the uplink collision permissible
channel.
[0128] In the example shown in FIG. 11B, the mobile terminal A-C
transmits the uplink collision permissible channel within a range
of a predetermined bandwidth greater than the minimum bandwidth of
the system, for example, within a range of the bandwidth of 5 MHz.
Also in this case, any one of the methods of (1) transmitting using
a band specified from the base station, (2) transmitting within a
range of a reception permissible bandwidth determined by the base
station beforehand, and (3) determining randomly by the mobile
terminal can be used. By the way, in the examples shown in FIGS.
11A and 11B, although the bandwidth assigned to the uplink
collision permissible type channel is set to be small compared with
the bandwidth of the system, the whole bandwidth of the system may
be assigned as the band of the uplink collision permissible type
channel depending on circumstances. Further, the bandwidth assigned
to the collision permissible type channel is determined depending
on a size of the system bandwidth, a number of mobile terminals
accessing using the uplink, and a size of information amount
necessary for the collision permissible type channel. In addition,
when the bandwidth assigned for the uplink collision permissible
type channel is greater than a band used for actually transmitting
the collision permissible type channel, the mobile terminal
performing accesses using the collision permissible type channel
can perform transmission by temporally changing the frequency of
the collision permissible type channel to be transmitted. In this
case, improvement of communication quality can be realized due to
frequency diversity effect.
[0129] Although the present invention is described based on
preferred embodiments, the present invention is not limited to
these examples, and various modifications and addition can be made
for a person skilled in the art.
[0130] The present application claims priority based on Japanese
patent application No. 2005-317572, filed in the JPO on Oct. 31,
2005 and the entire contents of the Japanese patent application is
incorporated herein by reference.
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