Description
Title of Invention
SP253830W000
BASE STATION, TERMINAL APPARATUS, COMMUNICATION CONTROL
5 METHOD AND RADIO COMMUNICATION SYSTEM
Technical Field
[0001 ]
The present invention relates to a base station, a terminal apparatus, a
10 communication control method, and a radio communication system.
Background Art
[0002]
In Long Term Evolution-Advanced (LTE-A), which is the next-generation
15 cellular communication standard that is discussed in Third Generation Partnership
Project (3GPP), introduction of technology called carrier aggregation (CA) has been
studied. The carrier aggregation is technology that forms a communication channel
between a user equipment (UE) and a base station (BS, or evolved Node B (eNB)) by
aggregating a plurality of frequency bands that are supported in LTE, for example,
20 and thereby improves communication throughput . Each frequency band included in
one communication channel that is formed by the carrier aggregation is called a
component carrier (CC). The bandwidths of frequency bands that are available in
LTE are 1.4 MHz, 3.0 MHz, 5.0 MHz, 10 MHz, 15 MHz, and 20 MHz.
Accordingly, if five bands of 20 MHz are aggregated as component carriers, a
25 communication channel of 100 MHz in total can be formed.
[0003]
Component carriers that are included in one communication channel in the
carrier aggregation are not necessarily contiguous to one another in the frequency
direction. The mode in which component carriers are arranged contiguous to one
30 another in the frequency direction is called a contiguous mode. On the other hand,
the mode in which component carriers are arranged not contiguous to one another is
2/33
called a non-contiguous mode.
[0004]
SP253830W000
Further, in the carrier aggregation, the number of component carriers in an
uplink and the number of component carriers in a downlink are not necessarily equal.
5 The mode in which the number of component carriers in an uplink and the number of
component carriers in a downlink are equal is called a symmetric mode. On the
other hand, the mode in which the number of component carriers in an uplink and the
number of component carriers in a downlink are not equal is called an asymmetric
mode. For example, in the case of using two component carriers in an uplink and
10 three component carriers in a downlink, it can be called asymmetric carrier
aggregation.
[0003]
Further, in LTE, any one of frequency division duplex (FDD) and time
division duplex (TDD) can be used as duplex operation. Because the direction of a
15 fink (uplink or downlink) of each component carrier does not change in time in FDD,
FDD is better suited to the carrier aggregation compared to TDD.
[0006]
The carrier aggregation technology is described in, for example, Non-Patent
Literature 1.
20
Citation List
Non-Patent Literature
[0007]
Non-Patent Literature 1: "LTE-Advanced and the Evolution to 40 Cellular
25 Systems" [online], [searched on January 5, 2010], Internet
.
Summary of Invention
Technical Problem
30 [0008]
If the carrier aggregation technology is used, as described above, radio
3/33
SP253830WOOD
communication can be performed in higher throughput compared to the past.
However, under current circumstances in which many users use radio
communication services such as packet-based voice calls and real-time video
delivery, further contrivances to improve communication characteristics are needed
5 to maintain a high service quality level. In the framework of IEEE802.11n, for
example, improving data communication characteristics by interleaving a series of
data signals between two channels having the bandwidth of 20 MHz is proposed.
However, the interleave between channels in IEEE802.11n is a static interleave
following an operation preset for an RF circuit. According to the technique of such
10 an interleave, if quality of a portion of channels deteriorates or a channel with less
available resources is present, expected characteristics may not be obtained. If a
technology .that adaptively interleaves in accordance with communication channel
conditions, by contrast, communication characteristics can be improved more
reliably in radio communication accompanied by carrier aggregation.
15 [0009]
Thus, the present invention provides a novel and improved base station
capable of interleaving adaptively in accordance with communication channel
conditions in radio communication accompanied by carrier aggregation, a terminal
apparatus, a communication control method, and a radio communication system.
20
Solution to Problem
[0010]
According to an embodiment of the present invention, there is provided a
base station performing radio communication with a terminal apparatus on a
25 communication channel formed by integrating a plurality of component carriers, the
base station including: a quality acquisition unit that acquires channel quality of the
communication channel for each of the component carriers; and an interleaver that
interleaves data signals transmitted on the communication channel in accordance
with at least one of the channel quality acquired by the quality acquisition unit and
30 available situations of communication resources for each of the component carriers.
[0011]
4/33
SP253830W000
When each of the data signals transmitted on the communication channel is
classified into one of two or more classes in accordance with service quality
requirements, the interleaver may mix, into one component carrier, a plurality of the
data signals each of which is classified into the two or more classes.
5 [0012]
When each of the data signals transmitted on the communication channel is
classified into one of two or more classes in accordance with service quality
requirements, the interleaver may frequency-interleave the data signal classified into
one class between the plurality of component carriers in accordance with at least one
10 of the channel quality acquired by the quality acquisition unit and the available
situations of communication resources.
[0013]
The interleaver may not distribute bits of the data signals classified into the
class in which the relatively high service quality is required to the component carrier
15 that does not maintain a predetermined quality level.
[0014]
The interleaver may distribute bits of each of the data signals to one or more
component carriers having available resources exceeding a certain ratio present
therein and maintaining a predetermined quality level.
20 [0015]
When bits of the data signal classified into one class are distributed to two
or more component carriers, a percentage of distribution of bits may be decided in
accordance with at least one of the channel quality for each of the component carriers
and the available situations of communication resources.
25 [0016]
When each of the data signals transmitted on the communication channel is
classified into one of two or more classes in accordance with service quality
requirements, the interleaver may mix, into one resource block, a plurality of the data
signals each of which is classified into the two or more classes.
30 [0017]
The interleaver may further time4nterleave each of the data signals.
5/33
[0018]
5P253830W000
The interleaver may further space-interleave each of the data signals by
using a plurality of antennas.
[0019]
5 According to another embodiment of the present invention, there is provided
a terminal apparatus performing radio communication with a base station on a
communication channel formed by integrating a plurality of component carriers, the
terminal apparatus including: a radio communication unit that transmits/receives data
signals interleaved in accordance with at least one of channel quality of the
10 communication channel for each of the component carriers and available situations
of communication resources for each of the component carriers to/from the base
station.
[0020]
According to another embodiment of the present invention, there is provided
15 a communication control method to control radio communication with a terminal
apparatus on a communication channel formed by integrating a plurality of
component carriers from a base station, the method including the steps of: acquiring
channel quality of the communication channel for each component carrier; judging,
for each component carrier, available situations of communication resources
20 allocated to the radio communication; and interleaving data signals transmitted on
the communication channel in accordance with at least one of the channel quality and
the available situations of communication resources.
[002l]
According to another embodiment of the present invention, there is provided
25 a radio communication system containing a base station and a terminal apparatus that
perform radio communication with each other on a communication channel formed
by integrating a plurality of component carriers, wherein the base station includes: a
quality acquisition unit that acquires channel quality of the communication channel
for each of the component carriers; and an interleaver that interleaves data signals
30 transmitted on the communication channel in accordance with at least one of the
channel quality acquired by the quality acquisition unit and available situations of
6/33
SP253830W000
communication resources for each of the component carriers, and the terminal
apparatus includes a radio communication unit that receives the data signals
interleaved by the interleaver of the base station from the base station.
5 Advantageous Effects of Invention
[0022]
As described above, a base station, a terminal apparatus, a communication
control method, and a radio communication system according to the present
invention can adaptively interleave in accordance with communication channel
10 conditions.
Brief Description of Drawings
[0023]
[Fig. 1] Fig. 1 is a schematic diagram showing an overview of a radio
15 communication system according to an embodiment.
[Fig. 2] Fig. 2 is an explanatory view exemplifying the configuration of
communication resources.
[Fig. 3] Fig. 3 is an explanatory view illustrating configuration examples of data
packets.
20 [Fig. 4] Fig. 4 is a block diagram exemplifying the configuration of a terminal
apparatus according to an embodiment.
[Fig. 5] Fig. 5 is a block diagram exemplifying the configuration of a base station
according to an embodiment.
[Fig. 6] Fig. 6 is a block diagram exemplifying a detailed configuration of a radio
25 communication unit according to an embodiment.
[Fig. 7A1 Fig. 7A is an explanatory view illustrating a first example of interleave
processing according to an embodiment.
[Fig. 7B] Fig. 7B is an explanatory view illustrating a second example of the
interleave processing according to the embodiment.
30 [Fig. 7C] Fig. 7C is an explanatory view illustrating a third example of the interleave
processing according to the embodiment.
%/33
5P253830W000
[Fig. 8] Fig. 8 is an explanatory view illustrating a first pattern of mapping between
component carriers and QoS classes.
[Fig. 9] Fig. 9 is an explanatory view illustrating a second pattern of the mapping
between component carriers and QoS classes.
5 [Fig. l0A] Fig. 1OA is an explanatory view illustrating a first example of a third
pattern of the mapping between component carriers and QoS classes.
[Fig. I OB] Fig. l OB is an explanatory view illustrating a second example of the third
pattern of the mapping between component carriers and QoS classes.
[Fig. 1OC] Fig. 10C is an explanatory view illustrating a third example of the third
10 pattern of the mapping between component carriers and QoS classes.
[Fig. 10D] Fig. 1OD is an explanatory view illustrating a fourth example of the third
pattern of the mapping between component carriers and QoS classes.
Description of Embodiments
15 [0024]
Hereinafter, preferred embodiments of the present invention will be
described in detail with reference to the appended drawings. Note that, in this
specification and the drawings, elements that have substantially the same function
and structure are denoted with the same reference signs, and repeated explanation is
20 omitted.
[0025]
" Description of Embodiments "will be described in the following order:
1. Overview of Radio Communication System
1-1. Overall Image of System
25 1-2. Configuration of Communication Resources
1-3. Classification of Service Quality Requirements
2. Configuration Example of Apparatus According to An Embodiment
2-1. Configuration Example of Terminal Apparatus
2-2. Configuration Example of Base Station
30 2-3. Configuration Example of Interleave Processing
2-4. Mapping Between Component Carriers and Classes
8/33
3. Conclusion
[0026]
SP253830W000
<1. Overview of Radio Communication System>
[1-1. Overall Image of System]
5 Fig. 1 is a schematic diagram showing an overview of a radio
communication system 1 according to an embodiment of the present invention.
Reference to Fig. 1 shows that the radio communication system 1 includes one or
more terminal apparatuses 100 and a base station 200.
[0027]
10 The terminal apparatus 100 is positioned inside a cell 202 in which radio
communication services are provided by the base station 200. The terminal
apparatus 100 performs data communication with another terminal apparatus inside
or outside the cell 202 via the base station 200 on a communication channel formed
by combining a plurality of component carriers (that is, by carrier aggregation).
15 The base station 200 provides communication services to the terminal apparatuses
100 positioned inside the cell 202 on a communication channel formed by combining
a plurality of component carriers. The base station 200 can also communicate with
other base stations via a backbone link (for example, the X2 interface). Further, the
base station 200 can also communicate with an upper node such as Serving-Gateway
20 (S-GW) and MME via, for example, the S l interface.
[0028]
[1-2. Configuration of Communication Resources]
Fig. 2 shows the configuration of communication resources in LTE as an
example of the configuration of communication resources to which the present
25 invention can be applied. Reference to Fig. 2 shows that communication resources
in LTE are divided into individual radio frames having the length of 10 msec in a
time direction. Further, one radio frame contains 10 subframes and one subframe is
formed of two slots of 0.5 ms. In LTE, the subframe is the unit in which
communication resources are allocated to each terminal apparatus in the time
30 direction. The unit is called a Resource Block. One Resource Block contains 12
sub-carriers in a frequency direction. That is, one Resource Block contains a size of
9/33
SP253830WO00
1 msec x 12 subcarriers in a time-frequency region. If the bandwidth and the time
length are the same, throughput of data communication grows with an increasing
number of Resource Blocks allocated for data communication. In the radio
communication system 1 shown in Fig. 1, the base station 200 decides allocation of
5 communication resources to each of the terminal apparatuses 100. For example, the
base station 200 delivers scheduling information to the terminal apparatus 100 on a
broadcast channel of a downlink.
[0029]
[1-3. Classification of Service Quality Requirements]
10 In the radio communication system 1, each data signal transmitted on the
above communication channel classified into one of two or more classes in
accordance with service quality requirements (hereinafter, referred to as QoS
(Quality of Service) requirements) of traffic . Two or more classes in accordance
with QoS requirements may be, for example, four classes (hereinafter, referred to as
15 QoS classes) shown in Table 1. In Table 1, the class name, attribute examples
concerning QoS requirements of the class, and examples of corresponding services
are shown for each of the four QoS classes.
[0030]
[Table 1]
Table 1. Example of classification
Class name Attribute examples Service examples
concerning QoS
requirements
Conversational Error rate VoIP
Transfer delay Video conference
Guaranteed bit rate
Streaming Error rate Real-time video delivery
Transfer delay
Guaranteed bit rate
Interactive Error rate Web access
Database search
Background Error rate E-mail
SMS
20
[0031]
10/33
SP253830W000
First, the first QoS class is the "Conversational" class. For traffic of the
"Conversational" class, as an example, three attributes of the error rate, transfer delay,
and guaranteed bit rate are defined as QoS requirements to be met.
[0032]
5 The error rate can be expressed as, for example, an SDU (Service Data Unit)
error ratio or a residual bit error ratio. The SDU error ratio represents the ratio of
SDUs in which an error is detected to transmitted SDUs. The residual bit error ratio
is the ratio of bits that are not detected on the receiving side to transmitted data bits.
The transfer delay is a delay amount permitted during transmission. The guaranteed
10 bit rate refers to the bit rate guaranteed to terminal apparatuses by the radio
communication system 1. Instead of the guaranteed bit rate (or in addition to the
guaranteed bit rate), the maximum bit rate may be used.
[0033]
As is understood from Table 1, the radio communication system I schedules
15 communication resources for traffic belonging to the "Conversational" class so that
the error rate, transfer delay, and guaranteed bit rate do not fall below predetermined
reference values. Examples of services corresponding to the "Conversational" class
include the VoIP (Voice over IP) and video conference.
[0034]
20 The second QoS class is the "Streaming" class. Also for traffic of the
"Streaming" class, three attributes of the error rate, transfer delay, and guaranteed bit
rate are defined as QoS requirements to be met. However, reference values of QoS
requirements concerning these attributes may be different from reference values in
the "Conversational" class. Examples of services corresponding to the "Streaming"
25 class include real-time video delivery.
[0035]
The third QoS class is the "Interactive" class. For traffic of the
"Interactive" class, for example, only the error rate is defined as QoS requirements to
be met. Examples of services corresponding to the "Interactive" class include Web
30 access and database search.
[0036]
11/33
5P253830W000
The fourth QoS class is the "Background" class. Also for traffic of the
"Background" class, for example, only the error rate is defined as QoS requirements
to be met. However, the reference value of the error rate may be different from the
reference value in the "Interactive" class. Examples of services corresponding to
the "Background" class include the E-mail and SMS (Short Messaging Service).
[0037]
Classification of QoS classes shown in Table 1 is only an example. For
example, independent QoS classes for control signaling such as IMS (Information
Management Signaling) may be defined. Stringent (or high-priority) QoS
10 requirements can be imposed on QoS classes for control signaling than on the above
QoS classes for data signals. Into which of these QoS classes to classify each data
signal is decided by, for example, individual service applications and is indicated in,
for example, the header of a data packet.
[0038]
15 Fig. 3 is an explanatory view illustrating configuration examples of data
packets that can be transmitted by the radio communication system 1. Reference of
Fig. 3 shows four data packets 4a, 4b, 4c, and 4d.
[0039]
The data packet 4a is constituted of a header section and a data section.
20 The data section of the data packet 4a contains data bits of the class Ci. For
example, the class Ci may be one of C1="Conversational", C2="Streaming", and
C3="Interactive", and C4="Background". That is, in this case, the data packet 4a is
a packet having only a data signal of a single class.
[0040]
25 The data section of the data packet 4b contains data bits of the class Ci and
the class Cj. For example, the class Cj may also be one (but is different from the
class Ci) of C1="Conversational", C2=" Streaming", and C3="Interactive", and
C4="Background". Thus, data bits of different QoS classes may be contained in
one data packet mixedly.
30 [0041]
The data packet 4c is a data packet distributed over a plurality of MIMO
12/33
SP253930W000
(Multiple Input Multiple Output) streams. The data section of the first MIMO
stream among these streams contains data bits of the class Ci. The data section of
the second MIMO stream contains data bits of the class Cj. Thus, data bits of
different QoS classes may be contained in each of the data packets distributed over
5 the plurality of MIMO streams. Further, like the data packet 4d, data bits of two or
more different QoS classes may be contained in each of data packets distributed over
a plurality of MIMO streams.
[0042]
In the present embodiment, the radio communication system 1 performs
10 radio communication accompanied by carrier aggregation in an environment in
which data signals of the plurality of QoS classes can be mixed. Data signals
transmitted between the terminal apparatus 100 and the base station 200 are
adaptively interleaved depending on communication channel conditions, as will be
described in detail in the next paragraph.
15 [0043]
<2. Configuration Example of Apparatus According to An Embodiment>
[2-1. Configuration Example of Terminal Apparatus]
Fig. 4 is a block diagram exemplifying the configuration of the terminal
apparatus 100 according to the present embodiment. Reference to Fig. 4 shows that
20 the terminal apparatus 100 includes a radio communication unit 110, a signal
processing unit 150, a control unit 160, and a measuring unit 170.
[0044]
(Radio communication unit)
The radio communication unit 110 performs radio communication with the
25 base station 200 on a communication channel formed by integrating a plurality of
component carriers by using the carrier aggregation technology. Data signals
transmitted to or received from the base station 200 are, as will be further described
below, data signals interleaved in accordance with channel quality for each
component carrier or available situations of communication resources for each
30 component carrier.
[0045]
13/33
SP253830W000
For example, as shown in Fig. 4, the radio communication unit 110 includes
an interleaver 112 and a deinterleaver 114. The interleaver 112 interleaves bit
strings of a data signal input from the signal processing unit 150 under the control of
the control unit 160. Then, the radio communication unit 110 sends out a data
5 signal interleaved by the interleaver 112 onto a communication channel to the base
station 200. On the other hand, the deinterleaver 114 deinterleaves bit strings of a
data signal received via a communication channel to the base station 200 under the
control of the control unit 160. Then, the radio communication unit 110 outputs a
data signal deinterleaved by the deinterleaver 114 to the signal processing unit 150.
10 [0046]
(Signal processing unit)
The signal processing unit 150 performs'signal processing such as decoding
and error corrections on a data signal input from the radio communication unit 110.
Then, the signal processing unit 150 outputs a processed data signal to an upper layer.
15 The signal processing unit 150 also performs signal processing such as encoding on a
data signal input from an upper layer. Then, the signal processing unit 150 outputs
a processed data signal to the radio communication unit 110.
[0047]
(Control unit)
20 The control unit 160 controls functions of the terminal apparatus 100 as a
whole by using a processing unit such as a CPU (Central Processing Unit) and DSP
(Digital Signal Processor). For example, the control unit 160 controls the timing of
data communication by the radio communication unit 110 according to scheduling
information received by the radio communication unit 110 from the base station 200.
25 The control unit 160 also causes the measuring unit 170 to measure channel quality
of each component carrier (more suitably, each Resource Block in each component
carrier) by using a reference signal from the base station 200 to transmit a channel
quality report to the base station 200 via the radio communication unit 110. The
control unit 160 also receives control information about mapping between each
30 component carrier and the QoS class of each data signal from the base station 200 via
the radio communication unit 110. The control information may be the same
14/33
SP253830W000
information as the above scheduling information or different information. Then, the
control unit 160 controls processing of the interleaver 112 or the deinterleaver 114 of
the radio communication unit 110 according to the control information.
[0048]
5 (Measuring unit)
The measuring unit 170 measures channel quality by using a reference
signal from the base station 200, for example, under the control of the control unit
160. A measurement result by the measuring unit 170 is converted into a
predetermined format by the control unit 160 and transmitted to the base station 200
10 via the radio communication unit 110. A measurement result of the channel quality
is used for mapping between each component carrier and the QoS class of each data
signal in the base station 200.
[0049]
[2-2. Configuration Example of Base Station]
15 Fig. 5 is a block diagram exemplifying the configuration of the base station
200 according to the present embodiment. Reference to Fig. 5 shows that the base
station 200 includes a radio communication unit 210, an interface unit 250, a storage
unit 260, a quality acquisition unit 268, a control unit 270, and a QoS management
unit 280.
20 [0050]
(Radio communication unit)
The radio communication unit 210 performs radio communication with the
terminal apparatus 100 on a communication channel formed by integrating a plurality
of component carriers by using the carrier aggregation technology. The radio
25 communication unit 210 includes an interleaver 212 and a deinterleaver 214. The
interleaver 212 interleavs bit strings of a data signal input from the interface unit 250
under the control of the control unit 270. Then, the radio communication unit 210
sends out a data signal interleaved by the interleaver 212 onto a communication
channel to the terminal apparatus 100. On the other hand, the deinterleaver 214
30 deinterleaves bit strings of a data signal received via a communication channel to the
terminal apparatus 100 under the control of the control unit 270. Then, the radio
15/33
SP253830W000
communication unit 210 outputs a data signal deinterleaved by the deinterleaver 214
to the interface unit 250.
[0051]
Fig. 6 is a block diagram exemplifying a detailed configuration of the radio
5 communication unit 210. Reference to Fig. 6 shows that the radio communication
unit 210 includes an antenna 216, an LNA (Low Noise Amplifier) 220, a plurality of
down-converters 222a to 222c, a plurality of filters 224a to 224c, a plurality of ADC
(Analogue to Digital Converter) 226a to 226c, a demodulation unit 228, the
deinterleaver 214, the interleaver 212, a modulation unit 230, a plurality of DAC
10 (Digital to Analogue Converter) 232a to 232c, further a plurality of filters 234a to
234c, a plurality of up-converter 236a to 236c, a synthesizer 238, a PA (Power
Amplifier) 240, and an antenna 242.
[0052]
When a radio signal transmitted from the terminal apparatus 100 is received,
15 the antenna 216 outputs the received signal to the LNA 220. The LNA 220
amplifies the received signal. The down-converter 222a and the filter 224a separate
a baseband signal of a first component carrier (CC l) from the received signal
amplified by the LNA 220. Then, the separated baseband signal is converted into a
digital signal by the ADC 226a and output to the demodulation unit 228. Similarly,
20 the down-converter 222b and the filter 224b separate a baseband signal of a second
component carrier (CC2) from the received signal amplified by the LNA 220. Then,
the separated baseband signal is converted into a digital signal by the ADC 226b and
output to the demodulation unit 228. Also, the down-converter 222c and the filter
224c separate a baseband signal of a third component carrier (CC3) from the
25 received signal amplified by the LNA 220. Then, the separated baseband signal is
converted into a digital signal by the ADC 226c and output to the demodulation unit
228. Subsequently, the demodulation unit 228 generates a data signal by
demodulating the baseband signal of each component carrier and outputs the data
signal to the deinterleaver 214. The deinterleaver 214 deinterleaves the data signal
30 input from the demodulation unit 228 and outputs the deinterleaved data signal to the
signal processing unit 250.
16/33
[0053]
SP253830W000
If a data signal is input from the signal processing unit 250, the interleaver
212 interleaves the data signal and outputs the interleaved data signal to the
modulation unit 230. The modulation unit 230 modulates the data signal input from
5 the interleaver 212 to generate a baseband signal for each component carrier. The
baseband signal of the first component carrier (CC1) among these baseband signals
is converted into an analog signal by the DAC 232a. Then, a frequency component
corresponding to the first component carrier of a transmission signal is generated by
the filter 234a and the up-converter 236a from the analog signal. Similarly, the
10 baseband signal of the second component carrier (CC2) is converted into an analog
signal by the DAC 232b. Then, a frequency component corresponding to the
second component carrier of the transmission signal is, generated by the filter 234b
and the up-converter 236b from the analog signal. Also, the baseband signal of the
third component carrier (CC3) is converted into an analog signal by the DAC 232c.
15 Then, a frequency component corresponding to the third component carrier of the
transmission signal is generated by the filter 234c and the up-converter 236c from the
analog signal. Subsequently, frequency components corresponding to the three
generated component carriers are synthesized by the synthesizer 238 to form a
transmission signal. The PA 240 amplifies the transmission signal and then outputs
20 the transmission signal to the antenna 242. Then, the antenna 242 transmits the
transmission signal to the terminal apparatus 100 as a radio signal.
[0054]
The radio communication unit 110 of the terminal apparatus 100 shown in
Fig. 4 is configured in the same manner as the configuration of the radio
25 communication unit 210 of the base station 200 described by using Fig. 6, though
requirements such as processing performance are different.
[0055]
In Fig. 6, an example in which the radio communication unit 210 handles
three component carriers is described, but the number of component carriers handled
30 by the radio communication unit 210 may be two or four or more. Also in Fig. 6,
an example in which the radio communication unit 210 has one receiving antenna
17/33
SP253830W000
216 and one transmitting antenna 242 is described. However, the radio
communication unit 210 may be configured to have a plurality of the receiving
antennas 216 and a plurality of the transmitting antennas 242 to handle a plurality of
MIMO (Multiple Input Multiple Output) streams.
5 [0056]
(Interface unit)
Returning to Fig. 5, the description of the example of the configuration of
the base station 200 will continue. The interface unit 250 mediates communication
between the radio communication unit 210, the control unit 270, and the QoS
10 management unit 280 and an upper node via, for example, the Si interface illustrated
in Fig. 1. The interface unit 250 mediates communication between the radio
communication unit 210, the control unit 270, and the Q,oS management unit 280 and
other base stations via, for example, the X2 interface illustrated in Fig. 1.
[0057]
15 (Storage unit)
The storage unit 260 holds CC management data indicating which
component carrier is used by each terminal apparatus to perform communication for
each terminal apparatus belonging to the cell of the base station 200 by using a
storage medium such as a hard disk and semiconductor memory. The CC
20 management data can be updated by the control unit 270 when a new terminal
apparatus participates in the cell of the base station 200 or an existing terminal
apparatus changes the component carrier. Therefore, the control unit 270 can know
which component carrier the terminal apparatus 100 muses by referring to the CC
management data.
25 [0058]
The storage unit 260 also holds QoS data indicating attribute values such as
the error rate, transfer delay, and guaranteed bit rate for each QoS class to be met by
traffic. The QoS data is used to decide mapping between each component carrier
and the QoS class of each data signal when communication resources are scheduled.
30 [0059]
(Quality acquisition unit)
18/33
SP253830W000
The quality acquisition unit 268 acquires channel quality for each
component carrier of communication channels to the terminal apparatus 100. For
example, the quality acquisition unit 268 may acquire a channel quality report
transmitted from the terminal apparatus 100 via the radio communication unit 210.
5 Instead, the quality acquisition unit 268 may acquire channel quality for each
component carrier by measuring the power level, error rate and the like of a received
signal in the radio communication unit 210. The quality acquisition unit 268
outputs the value of channel quality of each component carrier to the control unit 270.
[0060]
10 (Control unit)
The control unit 270 controls functions of the base station 200 as a whole by
usinga processing unit such as a CPU and DSP. For example, the control unit 270
schedules communication resources for data transmission by the terminal apparatus
100 based on attribute values for each QoS class to be met by traffic notified from
15 the QoS management unit 280. At this point, the control unit 270 decides mapping
between each component carrier and the QoS class of each data signal in accordance
with channel quality for each component carrier acquired by the quality acquisition
unit 268 and available situations of communication resources for each component
carrier. Three typical patterns (six variations) of such mapping will further be
20 described later by citing examples.
[0061]
The control unit 270 controls interleave processing by the interleaver 212 or
deinterleave processing by the deinterleaver 214 of a data signal transmitted on a
communication channel to the terminal apparatus 100 in accordance with a result of
25 mapping between each component carrier and the QoS class of each data signal.
Three examples of the configuration of interleave processing by the interleaver 212
will further be described later by citing examples.
[0062]
(QoS management unit)
30 The QoS management unit (also called a QoS manager) 280 commonly
manages QoS requirements to be met by traffic by using, for example, QoS data held
19/33
SP253830W000
by the storage unit 260. The QoS management unit 280 notifies the control unit
270 of QoS requirements for data signals to be scheduled before communication
resources being scheduled. If there is a possibility that QoS requirements are not
met, the QoS management unit 280 may negotiate with other base stations or an
5 upper node so that QoS requirements can be met by changing the path of RAN
(Radio Access Network) or utilizing a wire link.
[0063]
Instead of being arranged in the base station 200, the QoS management unit
280 may be arranged in an upper node of the base station 200. The upper node of
10 the base station 200 is a node corresponding to, for example, a serving gateway or
MME.
[0064]
[2-3. Configuration Example of Interleave Processing]
Next, three examples of the configuration of interleave processing by the
15 interleaver 212 will be described by using Figs . 7A to 7C. Incidentally, deinterleave
processing by the deinterleaver 214 can be configured as processing in the opposite
direction of the interleave processing. From the viewpoint of avoiding redundancy
of description, a detailed description of deinterleaveprocessing is omitted.
[0065]
20 (First example)
First, reference to Fig. 7A shows the configuration of the interleaver 212a
that frequency-interleaves (CC-interleaves) a data signal among a plurality of
component carriers . In the example of Fig. 7A, the interleaver 212a interleaves first
to sixth bits equally one bit after another among three component carriers. As a
25 result, the first and fourth bits are distributed to the first component carrier, the
second and fifth bits are distributed to the second component carrier, and the third
and sixth bits are distributed to the third component carrier.
[0066]
If, for example, available resources exceeding a certain ratio are present and
30 a plurality of component carriers maintaining a predetermined quality level is
available, the control unit 270 may equally distribute each data signal among such
20/33
SP253830WO00
component carriers regardless of the QoS class. Accordingly, interleave control is
simplified to reduce the load of processing and also an effect of improved link
characteristics by interleaving can be expected. Also, for example, the control unit
270 may not distribute a data signal classified into a class in which relatively high
5 service quality is required to a component carrier, among the three component
carriers, that does not maintain the predetermined quality level. The class in which
relatively high service quality is required may be, for example, the "Conversational"
class or the " Streaming" class shown in Table 1. Accordingly, an effect of improved
link characteristics by interleaving can be expected from a data signal on which
10 stringent (or high-priority) QoS requirements are imposed while avoiding risk of
violating QoS requirements. The control unit 270 can cause the interleaver 212 to
perform the above interleave processing by, for example, outputting a control signal
Sla to the interleaver 212.
[0067]
15 (Second example)
Reference to Fig. 7B shows the configuration of the interleaver 212b that
time-interleaves (bit-interleaves) before a data signal being frequency-interleaved.
In the example of Fig. 7B, the order of the first to fourth bits is rearranged to the
order of the fourth, first, third, and second bits. Then, these four bits are frequency-
20 interleaved among three component carriers. As a result, the fourth and second bits
are distributed to the first component carrier, the first bit is distributed to the second
component carrier, and the third bit is distributed to the third component carrier.
[0068]
Thus, by performing the time-interleave, in addition to the frequency-
25 interleave, for example, a weakened effect of improved characteristics by frequencyinterleaving
when the number of available component carriers is smaller (for
example, than a predetermined reference value) can be compensated for. Available
component carriers mean, for example, component carriers maintaining a
predetermined quality level and having sufficient available communication resources.
30 Therefore, if, for example, the number of available component carriers is judged to
fall below the predetermined reference value, the control unit 270 may cause the
21/33
interleaver 212b to time-interleave each data signal.
[0069]
SP253830W000
The pattern of rearranging bits in the time-interleave is, for example,
defined as communication specifications in advance. Accordingly, for example, bit
5 strings interleaved by the interleaver 212 of the base station 200 can be deinterleaved
by the deinterleaver 114 of the terminal apparatus 100.
[0070]
(Third example)
Reference to Fig. 7C shows the configuration of the interleaver 212c that
10 space-interleaves (stream-interleaves to a plurality of MIMO streams) after a data
signal being frequency-interleaved. In the example of Fig. 7C, the first to sixth bits
are equally interleaved one bit after another among three component carriers. As a
result, the first and fourth bits are distributed to the first component carrier, the
second and fifth bits are distributed to the second component carrier, and the third
15 and sixth bits are distributed to the third component carrier. Further, among bits
distributed to the first component carrier, the first and fourth bits are distributed to
different MIMO streams. Similarly, among bits distributed to the second
component carrier, the second and fifth bits are distributed to different MIMO
streams. Also, among bits distributed to the third component carrier, the third and
20 sixth bits are distributed to different MIMO streams.
[0071]
Thus, also by performing the space-interleave, in addition to the frequencyinterleave,
for example, a weakened effect of improved characteristics by frequencyinterleaving
when the number of available component carriers is smaller (for
25 example, than a predetermined reference value) can be compensated for. Therefore,
if, for example, the number of available component carriers is judged to fall below
the predetermined reference value, the control unit 270 may cause the interleaver
212c to space-interleave each data signal to a plurality of MIMO streams using a
plurality of MIMO antennas.
30 [0072]
The pattern of distributing bits to MIMO streams in the space-interleave is,
22/33
SP253830W000
for example, defined as communication specifications in advance. Accordingly, for
example, bit strings interleaved by the interleaver 212 of the base station 200 can be
deinterleaved by the deinterleaver 114 of the terminal apparatus 100.
[0073]
5 The frequency-interleave, time-interleave, and space-interleave described by
using Figs. 7A to 7C are not limited to combinations described herein and can be
used in any combination. For example, the interleaver 212 may be configured to
perform all of the frequency-interleave, time-interleave, and space-interleave. Also,
other processing may be interposed between the interleave processing. For example,
10 it is clear that encoding processing or the like may be performed in the timing
between the time-interleave and the frequency-interleave or between the frequencyinterleave
and the space-interleave.
[0074]
[2-4. Mapping Between Component Carriers and Classes]
15 Next, typical patterns of mapping between each component carrier and the
QoS class of each data signal will be described by using Figs. 8 to l OD.
[0075]
(First pattern)
Fig. 8 is an explanatory view illustrating a first pattern (pattern P1) of
20 mapping between each component carrier and the QoS class of each data signal.
The first pattern is a pattern that can be adopted when a data signal to be transmitted
contains data bits of a single QoS class.
[0076]
Reference to Fig. 8 shows that the data signal contains only data bits
25 belonging to the class Cl. The control unit 270 of the base station 200 distributes
such data bits equally or non-equally among component carriers. In the example of
Fig. 8, Resource Blocks in the component carriers CC1, CC2, CC3 are scheduled
non-equally in the ratio of 3:2:1 respectively. Such a ratio can be decided in
accordance with channel quality of each component carrier or available situations of
30 resource (for example, more bits are distributed to a component carrier in good
quality or a component carrier with more available resources).
23133
[0077]
SP25383OW000
(Second pattern)
Fig. 9 is an explanatory view illustrating a second pattern (pattern P2) of
mapping between each component carrier and the QoS class of each data signal.
5 The second pattern is a pattern that can be adopted when a data signal to be
transmitted contains data bits of a plurality of QoS classes.
[0078]
Reference to Fig. 9 shows that the data signal contains data bits belonging to
the classes Cl, C2, C3. The control unit 270 of the base station 200 distributes
10 these data bits to each component carrier so that data bits classified into different
classes are transmitted on, mutually different component carriers. If, for example,
QoS requirements of the class Cl are the most stringent (the highest priority), the
control unit 270 allocates data bits belonging to the class Cl to the component carrier
CC1 in the best channel quality. Also, the control unit 270 allocates data bits
15 belonging to the class C2 whose QoS requirements are the second most stringent (the
second highest priority) to the component carrier CC2 in the second best channel
quality. Further, the control unit 270 allocates data bits belonging to the class C3
whose QoS requirements are the most lax to the remaining component carrier CC3.
According to the second pattern described above, only data signals belonging to one
20 QoS class are transmitted on one component carrier and thus, costs needed for QoS
management are reduced.
[0079]
(Third pattern)
Figs. IOA to 1OD are explanatory views illustrating a third pattern of
25 mapping between each component carrier and the QoS class of each data signal.
The third pattern is, like the second pattern, a pattern that can be adopted when a data
signal to be transmitted contains data bits of a plurality of QoS classes . In the third
pattern, however, data bits classified into mutually different classes are distributed to
the common component carrier. Four variations of the third pattern, that is, patterns
30 P3a to P3d will be described one by one below.
[0080]
24/33
SP253830W000
Reference to Fig. 10A (pattern Pia) shows that the data signal contains data
bits belonging to the classes Cl, C2, C3. The control unit 270 of the base station
200 distributes these data bits to each component carrier in the same ratio. That is,
the ratio of data bits distributed to the component carrier CC1 and belonging to the
5 classes Cl, C2, C3 is equal to the ratios for the component carriers CC2, CC3.
According to the pattern P3a, the distribution of data bits can be decided by the
common ratio and thus, mapping processing is simplified and processing costs for
scheduling can be reduced. Moreover, due to an effect of the frequency-interleave,
better link characteristics can be obtained when compared with a case when data bits
10 belonging to the same class are simply distributed to the same component carrier.
[0081]
Referenceto Fig. I OB (pattern P3b) shows that the data signal contains data
bits belonging to the classes Cl, C2, C3. The control unit 270 of the base station
200 distributes these data bits in a ratio different from component carrier to
15 component carrier. In the example of Fig. 10B , data bits belonging to the classes
Cl, C2, C3 are distributed to the component carrier CCl. On the other hand, only
data bits belonging to the class Cl are distributed to the component carrier CC2.
Also, only data bits belonging to the classes C2, C3- are distributed to the component
carrier CC3 . According to the pattern P3b, the quantity of communication
20 resources allocated to each component carrier can be increased or decreased in
accordance with stringency (priority level) of QoS requirements . Therefore, more
flexible scheduling is enabled in order to meet the QoS requirements.
[0082]
Reference to Fig. 10C (pattern P3c) shows that the data signal contains data
25 bits belonging to the classes Cl, C2, C3. The control unit 270 of the base station
200 distributes these data bits to one component carrier . The pattern P3c can be
adopted when channel quality of one component carrier is far better than channel
quality of other component carriers and sufficient resources are available.
[0083]
30 Reference to Fig. IOD (pattern P3d) shows that the data signal contains data
bits belonging to the classes Cl, C2, C3. The control unit 270 of the base station
25/,33
SP253830W000
200 distributes these data bits in a ratio different from component carrier to
component carrier. In the pattern Pad, in contrast to the pattern P3b shown in Fig.
10B, the control unit 270 distributes data bits belonging to different classes to one
Resource Block. In the example of Fig. 10D, data bits belonging to the classes Cl,
5 C2, C3 are distributed to the component carrier CC2. Then, data bits belonging to
the classes Cl, C2 are distributed to a Resource Block RBI of the component carrier
CC2. Also, data bits belonging to the classes Cl, C3 are distributed to a Resource
Block RB2 of the component carrier CC2. According to the pattern P3d, more
flexible scheduling is enabled in accordance with quality in units of Resource Blocks.
10 [0084]
(Selection of mapping patterns)
When scheduling communication resources, the control unit 270 can make a
selection of which pattern of the above patterns to adopt in accordance with
variations in channel quality of each component carrier or available situations of
15 resources for each component carrier. Table 2 shows an example of selection
criteria of the mapping pattern. Here, a case when a data signal to be transmitted
contains data bits of a plurality of QoS classes will mainly be described.
[0085]
[Table 2]
Table 2. Exam le of selection criteria of the mapping pattern
Available Variations in quality
situations of All CCs meet Some CCs do not meet
resources predetermined criteria predetermined criteria
All CCs meet Case 1-1 Case 1-2
predetermined (Single class > P1 ) Pattern P3d
criteria A plurality of classes
Pattern P2 or Pia
Some CCs do Case 2-1 Case 2-2
not meet Pattern P3b Pattern P3c
predetermined
criteria
20
[0086]
In Table 2, available situations of resources are evaluated based on, for
example, the availability of resources for each component carrier. Variations in
26/33
SP253830W000
quality are evaluated based on, for example, channel quality for each component
carrier obtained through a channel quality report.
[0087]
As available situations of resources, for example, it is assumed that the
5 availability falls short of a predetermined ratio (that is, sufficient resources are
available) for all component carriers. Further, if channel quality of all component
carriers exceeds predetermined criteria, the control unit 270 can select the pattern P2
or the pattern P3a (case 1-1). Among these patterns, if it is desirable, for example,
to reduce costs needed for QoS management, the pattern P2 is selected. If it is
10 desirable, instead, to improve link characteristics, the pattern P3a may be selected.
[0088]
If available situations of resources are similar to the case 1-1 and a
component carrier whose channel quality does not meet predetermined criteria is
present, the control unit 270 can select the pattern P3d (case 1-2).
15 [0089]
If a component carrier whose availability exceeds predetermined criteria
(that is, sufficient resources are not available) is present and channel quality of all
component carriers exceeds predetermined criteria, the control unit 270 can select the
pattern P3b (case 2-1). If available situations of resources are similar to the case 2-
20 1 and a component carrier whose channel quality does not meet predetermined
criteria is present, the control unit 270 can select the pattern P3c (case 2-2).
[0090]
The control unit 270 of the base station 200 decides mapping between each
component carrier and the QoS class of each data signal based on the selection
25 criteria as an example. Then, the control unit 270 transmits control information
concerning the mapping to the terminal apparatus 100 via the radio communication
unit 210. The control information concerning the mapping may be, for example,
scheduling information delivered on a control channel or broadcast channel of a
downlink. The control information concerning mapping suitably represents
30 mapping between a Resource Block contained in each component carrier and the
QoS class of each data signal transmitted in the Resource Block. The control
27/33
SP253830W000
information concerning mapping may also contain, for example, identification code
that can identify the pattern of the adopted mapping and the pattern of interleaving.
Accordingly, the control unit 160 of the terminal apparatus 100 can control the
interleaver 112 or the deinterleaver 114 of the radio communication unit 110
5 according to the control information transmitted from the base station 200. The
control unit 270 also controls the interleaver 212 or the deinterleaver 214 of the radio
communication unit 210 in accordance with mapping between each component
carrier and the QoS class of each data signal.
[0091]
10 <5. Conclusion
Heretofore, the radio communication system 1 according to an embodiment
of the: present invention has been described by using Figs. 1 to l OD. According to
the present embodiment, a data signal transmitted on a communication channel
formed by carrier aggregation technology is interleaved in the base station 200 in
15 accordance with channel quality for each component carrier and available situations
of communication resources for each component carrier. That is, interleaving is
performed adaptively in accordance with communication channel conditions and thus,
the certainty with which an effect of interleaving can be enjoyed is increased. As a
result, communication characteristics are improved to be able to maintain a high
20 service quality. Because the frequency-interleave, time-interleave, and spaceinterleave
are used complementarily, the service quality level can be maintained even
in situations when an effect of the frequency-interleave between component carriers
cannot be expected much.
[0092]
25 It does not matter whether a sequence of processing according to an
embodiment described herein is realized by hardware or software. If a sequence of
processing or a portion thereof is performed by software, a program constituting the
software is stored in a hard disk or a storage medium such as a semiconductor
memory and is read into a RAM (Random Access Memory) during execution before
30 being executed by a processing unit such as a CPU and DSP.
[0093]
28/33
SP253830W000
The preferred embodiments of the present invention have been described
above with reference to the accompanying drawings, whilst the present invention is
not limited to the above examples, of course. A person skilled in the art may find
various alternations and modifications within the scope of the appended claims, and
5 it should be understood that they will naturally come under the technical scope of the
present invention.
Reference Signs List
[0094]
10 1
100
110
160
200
15 210
212
214
268
270
20 280
Radio communication system
Terminal apparatus
Radio communication unit
Control unit
Base station
Radio communication unit
Interleaver
Deinterleaver
Quality acquisition unit
Control unit
QoS management unit
29/33

CLAIMS
SP253830W000
Claim 1
A base station performing radio communication with a terminal apparatus
on a communication channel formed by integrating a plurality of component carriers,
5 the base station comprising:
a quality acquisition unit that acquires channel quality of the communication
channel for each of the component carriers; and
an interleaver that interleaves data signals transmitted on the communication
channel in accordance with at least one of the channel quality acquired by the quality
10 acquisition unit and available situations of communication resources for each of the
component carriers.
Claim 2
The base station according to claim 1, wherein each of the data signals
15 transmitted on the communication channel is classified into one of two or more
classes in accordance with service quality requirements, and
the interleaver mixes, into one component carrier, a plurality of the data
signals each of which is classified into the two or more classes.
20 Claim 3
The base station according to claim 1, wherein each of the data signals
transmitted on the communication channel is classified into one of two or more
classes in accordance with service quality requirements, and
the interleaver frequency-interleaves the data signal classified into one class
25 between the plurality of component carriers in accordance with at least one of the
channel quality acquired by the quality acquisition unit and the available situations of
communication resources.
Claim 4
30 The base station according to claim 2, wherein the interleaver does not
distribute bits of the data signals classified into the class in which the relatively high
30/33
SP253830W000
service quality is required to the component carrier that does not maintain a
predetermined quality level.
Claim 5
5 The base station according to claim 2, wherein the interleaver distributes
bits of each of the data signals to one or more component carriers having available
resources exceeding a certain ratio present therein and maintaining a predetermined
quality level.
10 Claim 6
The base station according to claim 2, wherein when bits of the data signal
classified into one class are distributed to two or more component carriers, a
percentage of distribution of bits is decided in accordance with at least one of the
channel quality for each of the component carriers and the available situations of
15 communication resources.
Claim 7
The base station according to claim 1, wherein each of the data signals
transmitted on the communication channel is classified into one of two or more
20 classes in accordance with service quality requirements, and
the interleaver mixes, into one resource block, a plurality of the data signals
each of which is classified into the two or more classes.
Claim 8
25 The base station according to claim 2, wherein the interleaver further timeinterleaves
each of the data signals.
Claim 9
The base station according to claim 2, wherein the interleaver further space-
30 interleaves each of the data signals by using a plurality of antennas.
31/33
SP253830W000
Claim 10
A terminal apparatus performing radio communication with a base station
on a communication channel formed by integrating a plurality of component carriers,
the terminal apparatus comprising:
5 a radio communication unit that transmits/receives data signals interleaved
in accordance with at least one of channel quality of the communication channel for
each of the component carriers and available situations of communication resources
for each of the component carriers to/from the base station.
10 Claim 11
A communication control method to control radio communication with a
terminal apparatus on a communication channel formed by integrating a plurality of
component carriers from a base station, the method comprising the steps of.
acquiring channel quality of the communication channel for each
15 component carrier;
judging, for each component carrier, available situations of communication
resources allocated to the radio communication; and
interleaving data signals transmitted on the communication channel in
accordance with at least one of the channel quality and the available situations of
20 communication resources.
Claim 12
A radio communication system containing a base station and a terminal
apparatus that perform radio communication with each other on a communication
25 channel formed by integrating a plurality of component carriers,
wherein the base station includes:
a quality acquisition unit that acquires channel quality of the communication
channel for each of the component carriers; and
an interleaver that interleaves data signals transmitted on the communication
30 channel in accordance with at least one of the channel quality acquired by the quality
acquisition unit and available situations of communication resources for each of the
SP2538_i0SVO00
32/33
component carriers, and
the terminal apparatus includes a radio communication unit that receives the
data signals interleavedby the interleaver of the base station from the base station.