DESCRIPTION
WIRELESS COMMUNICATION APPARATUS AND METHOD FOR WIRELESS
COMMUNICATION
TECHNICAL FIELD
The present invention relates to a wireless
communication apparatus and a method for wireless
communication that conform to a number of different wireless
communication systems.
BACKGROUND ART
WiMAX (Worldwide interoperability for Microwave
Access) is one of wireless broadband communication systems
being standardized in the IEEE (Institute of Electrical and
Electronic Engineers). For example, installation of a
function of a short distance wireless communication system,
such as Bluetooth (R) or WLAN (Wireless Local Aria Network),
to a mobile terminal complying with the wireless broadband
communication system such as WiMAX makes the mobile terminal
to solely perform a variety of functions.
Here, the frequency band of WiMAX and the frequency of
Bluetooth or WLAN overlap around 2.4 GHz. In other words, the
same frequency is competitively used by a number of
communication systems. For this reason, if a mobile terminal
which supports both communication of WiMAX and communication
of Bluetooth or WLAN carries out the both communication at the
same time through the overlapping frequency, one of
communications interferes with the other communication, which
may be a cause of lowering the throughput.
In order to inhibit interference among a number of
communication systems that uses the same wireless resource
(e.g., frequency, timing), one of effective solutions is to
control timings of data transmission and data reception of
respective communication systems so as not to overlap by
allocating a wireless resource to respective communication
systems through the TDM (Time Division Multiplexing) scheme.
For example, Patent Literature 1 describes a technique
of, in a mobile terminal which can transmit and receive
signals of a communication system (hereinafter sometimes
called WiMAX system) of WiMAX and signals of a communication
system (hereinafter sometimes called Bluetooth system) of
Bluetooth, transmitting and receiving the signals of the
Bluetooth system at a frame timing while the WiMAX system is
in a sleep mode.
Patent Literature 1: U.S. Patent Application Publication No.
US 2007/0232358
DISCLOSURE OF INVENTION
ISSUES TO BE SOLVED BY THE INVENTION
In a wireless communication system which carries out
data transmission and data reception through the use of
wireless frames synchronized with a base station, the base
station intensively controls allocation of wireless resource.
In this case, for example, it is inconvenient that a
mobile terminal confirming to a number of communication
systems independently decides to release a wireless resource
allocated to transmission of one of the communication systems
and to use the released resource for transmission of another
one of communication without negotiation with the base station.
To avoid this inconvenience, the base station controls
allocation of the wireless resource to a mobile terminal
communicable through a number of communication systems using
the same wireless resource (e.g., frequency) through the use
of the TDM scheme or the like such that timings of signal
transmission and receiving of the respective communication
system overlap.
However, increase in the number of mobile terminals
connected to a base station complicates management of the
wireless resource by the base station. Specifically in this
case, the base station negotiates with each individual mobile
terminal and controls the above allocation of the wireless
resource to the individual mobile terminal.
That increases processing load on the base station, so
that the throughput of communication with each mobile terminal
may be lowered.
In view of the above, the object of the embodiment to
be discussed herein is to lower possible interference in a
different approach from the conventional techniques.
Besides the above object, effects which the
configuration of the embodiment to be detailed below can
derive but which conventional technique cannot obtain can be
regarded as other objects of the present invention.
MEANS TO SOLVE THE ISSUES
For example, there is provided a wireless
communication apparatus including: a first signal
communicating unit that receives a first signal of a first
wireless communication system or transmits, based on
allocation information of a wireless communication resource
which information is transmitted in a predetermined cycle, the
first signal of the first wireless communication system; a
second signal communicating unit that receives or transmits a
second signal of a second wireless communication system
different from the first wireless communication system; and a
controller that restricts the first signal communicating unit
to transmit the first signal of the first wireless
communication system using a wireless communication resource
allocated by the allocation information while the second
signal communicating unit transmits or receives the second
signal.
EFFECTS OF THE INVENTION
It is possible to reduce possible interference among a
number of communication systems.
BRIEF DESCRIPTION OF DRAWINGS
[Fig. 1] A diagram illustrating an example of format
of a wireless frame used in a WiMAX system;
[Fig. 2] A diagram illustrating an example of a time
slot used in a Bluetooth system;
[Fig. 3] A diagram illustrating an example of
operation performed in a first embodiment;
[Fig. 4] A block diagram illustrating an example of
the configuration of a base station; and
[Fig. 5] A block diagram illustrating an example of
the configuration of a mobile station.
DESCRIPTION OF REFERENCE CHARACTERS
(base station)
101 upper layer
102 data frame processor
103 user data selector
104 scheduler
105 transmitting data generator
106 wireless resource mapping unit
107 transmitter
108 transmission and reception switch
109 antenna
110 receiver
111 receiving circuit
112 wireless quality information calculator
(mobile station)
201, 214 antenna
202, 215 transmission and reception switch
203, 216 demodulator
204 OFDMA data extracting unit
205 frame data extracting unit
206 wireless resource controller
207 MAP analyzer
208 error detector
209 retransmitting buffer
210 frame data allocating unit
211 OFDMA data allocating unit
212, 218 modulator
213, 217 timing generator
219 switch
BEST MODES FOR CARRYING OUT THE INVENTION
Hereinafter, description will now be made in relation
to a first embodiment with reference to accompanying drawings.
However, the embodiment to be detailed below is a mere example,
so there is no intention of excluding another embodiments and
variations and application of techniques that are not
mentioned in this specification. In other words, various
changes and modifications (e.g., combination of the
embodiments and the modifications) can be suggested without
departing from the spirit of the embodiment.
(1) the entire configuration of a first embodiment
(a) about WiMAX
[about Wireless frame]
As one example of communication schemes, WiMAX adopts
a communication scheme based on Orthogonal Frequency Division
Multiplexing (OFDMA).
A WiMAX system of the first embodiment uses wireless
frames defined in terms of the time axis segmented by OFDMA
symbol time and the frequency axis segmented by sub-channel
(logical set of orthogonal sub-carriers). For example, in
allocation of wireless frames, the base station segments the
time domain of a sub-channel shared by mobile terminals,
serving as examples of wireless communication apparatus, in
units of OFDMA symbol number and then dynamically allocates
the segmented sub-channel to respective mobile terminals.
To multiplex Downlink (DL) communication from a base
station to a mobile terminal (hereinafter also called "mobile
station") and Uplink (UL) communication from the mobile
terminal to the base station, Frequency Division Duplex (FDD)
scheme in which DL and UL use different frequency channels or
Time Division Duplex (TDD) scheme in which DL and UL use
different time domain on the same frequency channel.
Fig. 1 illustrates an example of the format of a TDD-
scheme wireless frame used in the WiMAX system.
In Fig. 1, the abscissa represents time (t); the
ordinate represents frequency (f); DL represents a DL sub-
frame used in downlink communication; and UL represents a UL
sub-frame used in uplink communication. TTG (Transmit /
Receive Transition Gap) and RTG (Receive / Transmit Transition
Gap) represent gaps due to transition between transmission and
reception.
The preamble in the front of the DL sub-frame is used
by each mobile terminal that transmits and receives signals to
and from a base station for synchronize with the base station.
FCH represents Frame Control Header including
information to specify the modulation scheme and the coding
scheme of the MAP information (DL-MAP, UL-MAP). By referring
the information in the FCH, the mobile terminal can correctly
demodulate and decode subsequent DL/UL-MAP. DL-MAP is
allocation information of DL Burst (frequency, timing) serving
an example of the wireless resource; and UL-MAP is allocation
information of UL Burst (frequency, timing) serving an example
of the wireless resource. DL Burst and UL Burst is a DL data
transmitting region and an UL data transmitting region,
respectively.
The allocation information (Burst Profile) of DL-MAP
and that of the UL-MAP include mapping information and
information about data transmitting schemes of the Bursts in
the DL sub-frames and the UL sub-frames, respectively.
Accordingly, the mobile terminal receives data in a region of
the DL Burst indicated by the DL-MAP and transmits data to the
base station in a region of the UL Burst indicated by the UL-
MAP. Providing that the transmission cycle defined by a DL
sub-frame and an UL sub-frame is one frame, the allocation
information of the UL-MAP may represent allocation of the UL
burst at the N-th frame (N is a natural number) or allocation
of the UL Burst at the (N+l)-th frame (or a subsequent frame).
Ranging Sub-channel is a transmitting region of a CDMA
(Code Division Multiple(sic)) Access) ranging code to be used
for ranging to adjust timing and transmitting electric power
level when the mobile terminal is establishing a connection to
the base station.
Allocation of the wireless resource is accomplished by
the mobile terminal transmitting a signal requesting a band
through which the mobile terminal communicates and the base
station mapping based on the information included in the
request signal.
[about Retransmission Control]
The WiMAX system includes a function of controlling
retransmission of data by means of Automatic Repeat Request
(ARQ) in a MAC (Medium Access Control) layer.
A receiver of data detects an error in received data
through the use of redundant bits for error detection that the
data transmitter attached to each data unit. If the receiver
detects an error in the received data or does not receive the
data, the receiver transmits a signal (NACK signal) that
requests the transmitter to retransmit, to the transmitter,
the data in which the error has been detected or the data
cannot be received by the receiver. Upon receipt of the NACK
signal, the transmitter retransmits the data for which
retransmission has been requested. If no error is detected in
the received data, the receiver transmits a signal (ACK
signal) notifying successful reception to the transmitter. In
response to receipt of the ACK signal, the transmitter
transmits another data to the receiver.
[0029] The above function of controlling retransmission makes
it possible to improve the reliability of data communication.
(b) about Bluetooth
Bluetooth carries out bidirectional communication of
data between a master and a slave, which carries out
communication under the control of the master, via TDD scheme.
For example, one second (s) is divided into 1,600 time
slots (625 us per time slot), and the time slots are allocated
time slot numbers tsO, tsl, ts2, .... The master transmits data
to the slave during, for example, even time slots while the
slave transmits data to the master during odd time slots.
Fig. 2 illustrates an example of time slot used in the
Bluetooth system. In Fig. 2, Tx and Rx represent transmitting
data and received data. As one example, the master transmits
data during time slots tsO and ts2 while the slave transmits
data during time slot tsl.
The master and the slave are independently of each
other capable of frequency hopping, that is, varying the
transmitting frequency for each data transmission.
Time slot may be a single slot in units of one slot
(625 us) and a multi slot in units of a number of slots, such
as three slots (1,875 us) or five slots (3,125 us). In a
single slot, data communication is carried out at the same
frequency throughout one slot; and in a multi slot, data
communication is carried out at the same frequency throughout
three or five slots.
Here, in Bluetooth, timing is adjusted by a clock
(counter) installed in a terminal having a Bluetooth
communication function. For example, the master and the slave
are synchronized with each other by calculating an offset of
clock values of the master and the slave and adding the offset
to either clock value.
(c) example of operation
Fig. 3 illustrates an example of operation performed
in the first embodiment.
Hereinafter, description will now be made in relation
to operation of a mobile terminal which is equipped with a
communication function of the WiMAX system (first wireless
communication system) and a communication function of the
Bluetooth system (second wireless communication system) and to
which the first embodiment is applied.
In Fig. 3, WiMAX BS (Base Station) and WiMAX MS
(Mobile Station) represent states of transmitting and
receiving signals (data) at the base station and the mobile
terminal, respectively.
"WiMAX frame" represents a wireless frame of the WiMAX
system. "DL sub-frame" represents a DL sub-frame. "UL sub-
frame" represents a UL sub-frame. Here, a set of a DL sub-
frame and a UL sub-frame is regarded as one frame and three
frames are a TDM controlling cycle. Hereinafter, the first,
the second, and the third frame in a single TDM controlling
cycle are simply called the first frame, the second frame, and
the third frame, respectively.
"Bluetooth PA (Power Amp) Enable" represents time
period during which the amplifier, such as a power amplifier,
included in a transmitting circuit in the Bluetooth'system is
enable or disable.
A period during which data transmission and reception
of the WiMAX system is restricted and during which
concurrently the Bluetooth is provided with an opportunity for
communication is defined as a Non-interfering period. In the
example of Fig. 3, the amplifier is enabled during the Non-
interfering period while is disabled during period except the
Non-interfering period. In other words, during the time slots
not included in the Non-interfering period, data transmission
of the Bluetooth system is restricted. The terms "restrict"
and "restriction" mean transmission and receiving processing
is stopped or limited (inhibited). The processing of
"limiting (inhibiting)" includes, for example, lowering the
transmitting power, that is, signal transmitting is continued
under a state of lowering the transmission power to an extent
that occurs no interference. As one example of the present
invention, the Non-interfering period is set in the first
frame of the TDM controlling cycle.
Bluetooth Slot represents time slots of the Bluetooth.
Tx represents a time slot for data transmission; Rx represents
a time slot for data reception; and Op represents an optional
time slot during which data can be transmitted and received.
A time slot with a cross (*) represents a time slot which is
not included in the Non-interfering period and during which
data transmission is inhibited.
Hereinafter, description will now be made in relation
to control over data transmission and reception at the mobile
terminal in a TDM controlling cycle.
In the first frame, the Non-interfering period is set
in the mobile terminal, and during the Non-interfering period,
the amplifier included in the transmitting circuit of the
Bluetooth system is enabled so that the data is transmitted in
the Bluetooth system.
Here, the Non-interfering period can be set so as not
overlap with a period during which Map information, to be
detailed below, in a DL sub-frame is transmitted from the base
station to the mobile terminal. This setting makes the mobile
station possible to improve the ratio of success in receiving
MAP information transmitted from the base station,
concurrently suppressing interference caused by transmitting
signals in the Bluetooth system.
Through the DL sub-frame of the first frame, the base
station transmits the MAP information to the mobile terminal
(SI). The MAP information includes information about DL-MAP
of the first frame, and UL-MAP information of the first or the
second frame. By referring the MAP information, the mobile
terminal can obtain the allocation information of the
communication region of the DL sub-frame or the UL sub-frame
of the first frame.
In succession, the base station transmits DL MAC-PDU
(DownLink Medium Access Control layer-Protocol Data Unit) #1
destined for the mobile terminal through the DL Burst region
of the DL sub-frame of the first frame (S2).
Since the Non-interfering period is concurrently set
in the mobile terminal, the amplifier included in the
transmitting circuit of the Bluetooth system is enabled, so
that data is transmitted in the time slot Tx and data is
received in the time slot Rx.
For the above, the signal including DL MAC-PDU #1
transmitted from the base station may be subjected to
interference with a Bluetooth signal transmitted at the time
slot Tx. If the interference is large enough to damage the DL
MAC-PDU #1, the mobile terminal detects an error in the data.
Through the UL sub-frame of the first frame, the
mobile terminal restricts (e.g., stops or limits transmitting
processing) data transmission of the WiMAX system, and in turn,
carries out data transmission of the Bluetooth system (S3).
This restricts the transmission of UL MAC-PDU #1, which should
be transmitted to the base station through the communication
region allocated in the same UL sub-frame. Accordingly, the
base station detects that the UL MAC-PDU #1 is not received or
that the reception of the UL MAC-PDU #1 is failed. The
restriction of data transmission of the WiMAX system in the
mobile terminal is withdrawn when the Non-interfering period
expires. In the example of Fig. 3, the Non-interfering period
expires at the end of the first frame. The timing of the
withdrawal is satisfactory any time point before the mobile
terminal receives the MAP information transmitted from the
base station in the next transmission cycle. The terms of
"withdraw" and "withdrawal" means that data transmission is
started or lowered transmission electric power is regained.
During the second and the third frames, the amplifier
included in the transmitting circuit of the Bluetooth system
is disabled, so that the data transmission of the Bluetooth
system is inhibited.
Through the DL sub-frame of the second frame, the base
station transmits MAP information about the DL sub-frame of
the second frame and the UL sub-frames of the second and the
third frames (S4) . The MAP information includes the DL-MAP of
the second frame and the UL-MAP of the second or the third
frame.
If the base station detects that the base station does
not receive the UL MAC-PDU #1 or failed in receiving the UL
MAC-PDU#1 from the mobile terminal, the base station transmits
a NACK signal for the UL MAC-PDU#1 through the DL sub-frame of
the second frame to the mobile station in order to request
retransmission of the data (S5).
If the mobile terminal detects that the mobile
terminal does not receive the DL MAC-PDU #1 or failed in
receiving the DL MAC-PDU #1 from the base station, the mobile
terminal transmits a NACK signal for the DL MAC-PDU#1 through
the UL sub-frame of the second frame to the base station in
order to request retransmission of the data (S6).
If the base station succeeds in receiving the UL MAC-
PDU#1 or the mobile station succeeds in receiving the DL MAC-
PDU#1 in the Non-interfering period, an ACK signal is returned
to the source that transmitted the data by means of the second
frame.
Due to some reason, such as processing load on the
base station and/or the mobile station, NACK and ACK signals
may be transmitted in the third frame or later.
Through the DL sub-frame of the third frame, the base
station transmits MAP information about the DL sub-frame and
the UL sub-frame of the third frame to the mobile station (S7).
The MAP information includes information about the DL-MAP of
the third frame and UL-MAP of the third frame or the first
frame of the next TDM controlling cycle.
If the base station receives the NACK signal through
the UL sub-frame of the second frame, the base station
transmits (retransmits) the DL MAC-PDU #1 to the mobile
station through the DL sub-frame of the third frame (S8) in
response to the reception of the NACK signal.
If the mobile station receives the NACK signal through
the DL sub-frame of the second frame from the base station,
the mobile terminal transmits (retransmits) the UL MAC-PDU #1
to the base station through the UL sub-frame of the third
frame (S9) in response to the reception of the NACK signal.
| The above procedure makes the mobile terminal possible
to correctly transmit or receive data of the WiMAX system,
which data has not been correctly transmitted to or received
from the base station during the Non-interfering period set in
the first frame, in the third frame or later. Furthermore,
during the Non-interfering period, data of the Bluetooth
system can be transmitted and received in a state of
inhibiting interference with signals of the WiMAX system, so
that communication throughput of the Bluetooth system can be
inhibited from lowering.
In the above example, the TDM controlling cycle is
assumed to include three frames, but is not limited to three
frames. Namely, a period set to be the Non-interfering period
and a period set to control retransmission of data of the
WiMAX system can be varied. For example, the TDM controlling
cycle may include a number of frames as many as the sum of the
frames of the Non-interfering period and frames that affords
to data retransmission control of the WiMAX system.
The above example restricts data transmission using a
UL sub-frame during the Non-interfering period in relation to
data transmission and reception of the WiMAX system at the
mobile terminal. Alternatively, data reception using the DL
sub-frame may be restricted (e.g., stop or limit reception
processing) during the same period. In other words, only
transmission may be restricted or both transmission and
reception may be restricted.
In the above example, the Non-interfering period is
set within the first frame, but alternatively may be a period
until the mobile terminal receives a NACK signal transmitted
from the base station through a DL sub-frame in the second
frame or later.
(2) an example of the configuration and the operation
of a base station used in the first embodiment
Fig. 4 is a block diagram illustrating an example of
the configuration of a base station of the first embodiment.
In Fig. 4, reference number 101 is an upper layer; 102
represents a data frame processor; 103 represents a user data
selector; 104 represents a scheduler; 105 represents a
transmitting data generator; 106 represents a wireless
resource mapping unit; 107 represents a transmitter; 108
represents a transmission and reception switch; 109 represents
an antenna; 110 represents a receiver; 111 represents a
receiving circuit; and 112 represents a wireless quality
information calculator.
The data frame processor 102 attaches a header to a
PDU forwarded from the upper layer 101, forms data to be
transmitted to each user (mobile terminal) communicating with
the base station into frames, and sends the transmitting data
in the form of frames to the user data selector 103.
The scheduler 104 controls allocation of a wireless
resource to transmit data sent to the user data selector 103
to respective mobile terminals. For example, the allocation
is accomplished in units of a frame of the transmitting data.
Information of allocation of the wireless resource by
the scheduler 104 is included in the MAP information generated
by the transmitting data generator 105. The MAP information
is mapped in the communication region (DL/UL-MAP) for the MAP
of the wireless resource in the wireless resource mapping unit
106, is modulated or otherwise processed by the transmitter
107, and is then transmitted (to the destinations) via the
antenna 109.
Data (including, for example, ACK/NACK signal and
various control messages) to be transmitted to respective
mobile terminal is mapped in respective communication regions
(DL/UL Bursts) of the wireless resource by the wireless
resource mapping unit 106 under the control of the scheduler
104, is modulated or otherwise processed by the transmitter
107, and is then transmitted (to the destinations) via the
antenna 109.
A signal received from each mobile terminal via the
antenna 109 is demodulated or otherwise processed by the
receiver 110 and is then transmitted to the receiving circuit
111. Received data included in the received signal is divided
into PDUs by the data frame processor 102 and is then
forwarded to the upper layer 101.
The receiving circuit 111 measures instantaneous
quality of the received signal and sends the measured
instantaneous quality information of the received signal of
each mobile terminal to the wireless quality information
calculator 112. The wireless quality information calculator
112 calculates the average wireless quality information for a
predetermined time period of each mobile terminal using
instantaneous quality information of the mobile terminal
received from the receiving circuit 111, and sends the average
wireless quality information to the scheduler 104. The
average the wireless quality information may be sent along
with the instantaneous quality information to the scheduler
104.
On the basis of the instantaneous quality information
and/or the average wireless quality information of each mobile
terminal sent from the wireless quality information calculator
112, the scheduler 104 allocates a wireless resource to the
respective mobile terminals.
The transmission and reception switch 108 switches
between transmission and reception such that, for example, the
antenna 109 is connected to a transmitting circuit including
the transmitter 107 during DL while the antenna 109 is
connected to the receiving circuit including the receiver 110
during UL.
(3) an example of the configuration and the operation
of a mobile terminal used in the first embodiment
Fig. 5 is a block diagram schematically illustrating an
example of the configuration of a mobile terminal according to
the first embodiment.
In the example of Fig. 5, the mobile terminal has
communication functions of a first communication system and a
second communication system exemplified by the WiMAX system
and the Bluetooth, respectively.
In the wireless unit (WiMAX wireless unit) of the
WiMAX system illustrated in Fig. 5, the reference number 201
represents an antenna; 202 represents a transmission and
reception switch; 203 represents a demodulator; 204 represents
OFDMA data extracting unit; 205 represents a frame data
extracting unit; 206 represents a wireless resource
controller; 207 represents a MAP analyzer; 208 represents an
error detector 208; 209 represents a retransmitting buffer;
210 represents a frame data allocating unit; 211 represents an
OFDMA data allocating unit; 212 represents a modulator; and
213 represents a timing generator.
In the wireless unit (Bluetooth wireless unit) of the
Bluetooth system illustrated in Fig. 5, the reference number
214 represents an antenna; 215 represents transmission and
reception switch; 216 represents a demodulator; 217 represents
a timing generator; 218 represents a modulator; and 219
represents a switch (SW).
The reference number 220 represents an upper layer
that provides various applications and others.
[0073] In the wireless unit of the WiMAX system, a signal
received through the antenna 201 is subjected orthogonal
demodulation in the demodulator 203 to be converted into a
digital signal, which is then sent to the OFDMA data
extracting unit 204. The demodulator 203 carries out
processing on the basis of timing signals which are generated
by the timing generator 213 and which are synchronized with
the base station.
The OFDMA data extracting unit 204 extracts
information about sub-carrier allocated to the mobile terminal
itself from information of respective sub-carrier obtained
through FFT (Fast Fourier Transform) on the received signal
from a time-axis signal to a freguency-axis signal under the
control of the wireless resource controller 206.
[0075] The frame data extracting unit 205 extracts
information of received data destined for the mobile terminal
itself from information extracted by the OFDMA data extracting
unit 204 under the control of the wireless resource controller
206.
Upon receipt of MAP information such as DL-MAP and UL-
MAP, the MAP analyzer 207 analyzes the received MAP
information and sends the wireless resource controller 206
allocation information of a wireless resource allocated to the
mobile terminal itself obtained by the result of the analysis.
Upon receipt of the allocation information of the
mobile terminal itself sent from the MAP analyzer 207, the
wireless resource controller 206 controls the OFDMA data
extracting unit 204, the frame data extracting unit 205, the
frame data allocating unit 210, and the OFDMA data allocating
unit 211 on the basis of the received allocation information.
During the Non-interfering period of the Fig. 3, the
wireless resource controller 206 restricts (stops or limits)
processing of the frame data allocating unit 210 and the OFDMA
data allocating unit 211. Additionally, during the Non-
interfering period, the wireless resource controller 206 may
restrict (stop or limit) the processing of the OFDMA data
extracting unit 204 and the frame data extracting unit 205.
The wireless resource controller 206 further turns
MON" the switch 219 included in the wireless unit of the
Bluetooth system during the Non-interfering period and turns
"OFF" the switch 219 during a period except of the Non-
interfering period. In other words, the wireless resource
controller 206 sends the switch 219 control signal that causes
the switch 219 to turn "OFF" during the Non-interfering period.
The received data destined to the mobile terminal
itself, which data is extracted by the frame data extracting
unit 205, is sent to the error detector 208, which then checks
the presence or the absence of an error in the received data
through the use of an error detection code, such as CRC,
attached to the received data. If no error is detected, the
same received data is forwarded to the upper layer 220. In
this case, the error detector 208 can send the frame data
allocating unit 210 a signal that instructs allocation of
transmission region to be used for transmitting an ACK signal
to the base station. Conversely, if an error is detected in
the received data, the error detector 208 sends the frame data
allocating unit 210 a signal that instructs allocation of
transmission region to be used for transmitting a signal (a
NACK signal) requesting the base station to retransmit the
same received data.
The retransmitting buffer 209 stores transmitting data
forwarded from the upper layer 209. The retransmitting buffer
209 stores transmitting data during the Non-interfering period
and, in the event of receipt of a NACK signal requesting
retransmission of data from the base station, sends the
transmitting data that the retransmitting buffer 209 is
storing to the frame data allocating unit 210 in response to
an instruction of the upper layer 220.
[0082] Under the control of the wireless resource controller
206, the frame data allocating unit 210 maps the transmitting
data on the wireless resource region allocated to the mobile
station itself, and further allocates a wireless resource to
transmit an ACK/NACK signal in responsive to the instruction
of the error detector 208.
Under the control of the wireless resource controller
206, the OFDMA data allocating unit 211 converts each sub-
carrier of the signal in which transmitting data has been
subjected to mapping by the frame data allocating unit 210
from a signal of the frequency axis to a signal to a time axis
through performing IFFT (Inverse Fast Fourier Transform), and
sends the signal obtained through the conversion to the
modulator 212.
During the Non-interfering period, processing of the
frame data allocating unit 210 and the OFDMA data allocating
unit 211 are restricted (stopped or limited) by the wireless
resource controller 206.
The signal obtained by the conversion in the OFDMA
data allocating unit 211 is converted to analog signal, which
is further subjected to orthogonal modulation, by the
modulator 212. The resultant analog signal is transmitted
through the antenna 201. The modulator 212 carries out
processing on the basis of timing signal which are generated
by the timing generator 213 and which are synchronized with
the base station.
The transmission and reception switch 202 switches
between the transmission and reception. For example, the
transmission and reception switch 202 switches a circuit such
that the antenna 201 is connected to the transmitting circuit
including the modulator 212 during UL while the antenna 201 is
connected to the receiving circuit including the demodulator
203 during DL. If antennas are provided one for each of the
transmitting circuit and the receiving circuit, the
transmission and reception switch 202 can be omitted.
The antenna 201 or the combination of the antenna 201
and the transmission and reception switch 202 can be regarded
as a first signal communication unit.
In the wireless unit of the Bluetooth, the
transmission and reception switch 215 switches between
transmitting and receiving at the antenna 214 for each time
slot. A received signal is demodulated by the demodulator 216
while the transmitting signal is modulated by the modulator
218. An exemplary modulating scheme of the Bluetooth is GFSK
(Gaussian Frequency Shift Keying). The modulator 218 and the
demodulator 216 perform on the basis of timing signals (i.e.,
clock) generated by the timing generator 217.
The switch 219 switches between ON/OFF, that is
enabling/disabling, of a non-illustrated amplifier (e.g. power
amplifier) for a transmitting signal. Under the control of
the wireless resource controller 206 of the wireless unit of
the WiMAX system, the switch 219 turns "ON" the amplifier
during the Non-interfering period while tunes "OFF" during a
period except for the Non-interfering period. Specifically,
upon receipt of a control signal from the wireless resource
controller 206, the switch 219 turns "OFF" the amplifier.
The combination of the antenna 214 and the
transmission and reception switch 215 can be regarded as a
second signal communication unit.
[0091] As described above, since the communication by the
wireless unit of the WiMAX system is restricted during the
Non-interfering period, occurrence of interference can be
stopped or inhibited, which makes it possible to inhibit the
throughput of transmitting and receiving signals in the
wireless unit of the Bluetooth system from lowering. In
contrast, since the communication by the wireless unit of the
Bluetooth system during a period except for the Non-
interfering period, data transmission of the wireless unit of
the WiMAX system which transmission has been restricted during
the Non-interfering unit can be carried out, suppressing
interfering with communication of the wireless unit of the
Bluetooth system.
(4) others
The above first embodiment assumes the second wireless
communication system coexists with the WiMAX system, that is
the first wireless communication system, to be Bluetooth. An
alternative to the second wireless communication system of the
first embodiment may be WLAN having a communication frequency
band overlapping with that of the WiMAX.
Alternatively, WLAN may be regarded as a third
wireless communication system and the first embodiment may be
applied to a case where both wireless communication systems
Bluetooth and WLAN coexist with the WiMAX. In this case, the
Non-interfering period can have communication period dedicated
to the WLAN in addition to the communication period dedicated
to the Bluetooth. Alternatively, a Non-interfering period
dedicated to the WLAN communication may be set in the TDM
controlling cycle separately from the Non-interfering period
dedicated to the Bluetooth communication.
[0094] Besides the above communication system , the first
embodiment can be applied to another system which employs a
first communication system that carries out communication
through wireless frames and which has a function of
retransmission, and a second wireless communication system
using wireless resource overlapping with wireless resource
that can be used by the first communication system.
1. A wireless communication apparatus comprising:
a first signal communicating unit that receives a
first signal of a first wireless communication system or
transmits, based on allocation information of a wireless
communication resource which information is transmitted in a
predetermined cycle, the first signal of the first wireless
communication system;
a second signal communicating unit that receives or
transmits a second signal of a second wireless communication
system different from the first wireless communication system;
and
a controller that restricts the first signal
communicating unit to transmit the first signal of the first
wireless communication system using a wireless communication
resource allocated by the allocation information while the
second signal communicating unit transmits or receives the
second signal.
2. A wireless communication apparatus according to
claim 1, wherein the controller withdraws the restriction by
the time the controller receives the allocation information
transmitted in the predetermined cycle after the controller
starts the restriction.
3. A wireless communication apparatus according to
claim 2, wherein the controller receives a request to
retransmit data which should be transmitted during the
restriction and transmits, based on the allocation information
received after the withdrawal of the restriction, the data in
response to the request.
4. A method for wireless communication, the method
comprising:
at a first signal communicating unit, receiving a
first signal of a first wireless communication system or
transmitting, based on allocation information of a wireless
communication resource which information is transmitted in a
predetermined cycle, the first signal of the first wireless
communication system;
at a second signal communicating unit, receiving or
transmitting a second signal of a second wireless
communication system different from the first wireless
communication system; and
restricting the first signal communicating unit to
transmit the first signal of the first wireless communication
system using a wireless communication resource allocated by
the allocation information while the second signal
communicating unit transmits or receives the second signal.

In order to reduce possible interference among
different communication systems, a wireless communication
apparatus includes: a first signal communicating unit that
receives a first signal of a first wireless communication
system or transmits, based on allocation information of a
wireless communication resource which information is
transmitted in a predetermined cycle, the first signal of the
first wireless communication system; a second signal
communicating unit that receives or transmits a second signal
of a second wireless communication system different from the
first wireless communication system; and a controller that
restricts the first signal communicating unit to transmit the
first signal of the first wireless communication system using
a wireless communication resource allocated by the allocation
information while the second signal communicating unit
transmits or receives the second signal.