JP2003273922A - Wireless communication device and wireless packet communication method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve the transmission quality of data requiring real-time property. SOLUTION: An application unit 110 notifies an MCS selection unit 180 of a required transmission rate required for transmitting real-time application data. Channel quality estimating section 170 estimates radio channel quality such as CIR from a pilot signal multiplexed on a radio channel.
The MCS selection unit 180 compares the radio channel quality estimation value estimated by the channel quality estimation unit 170 with the application unit 1
The MCS is selected based on the required transmission rate of the transmission data notified from 10. Multiplexing section 190 transmits transmission data output from IP control section 130 and MCS selecting section 180
And the information on the selected MCS.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a wireless communication device and a wireless communication method, and more particularly to a wireless communication device and a wireless communication method for performing downlink high-speed packet transmission.

[0002]

2. Description of the Related Art Conventionally, for example, HSDPA (High Speed D
In a downlink high-speed packet transmission system such as ownlink packet access, the base station device transmits a pilot signal through a common pilot channel (CPICH: Common PIlot CHannel). The wireless communication terminal apparatus receives the pilot signal and, for example, CIR (Carrier to Inter
(Channel Ratio) and other channel quality information are reported to the base station apparatus, and the base station apparatus transmits a transmission rate (MCS: Modulation Coding Scheme) including a modulation method and a coding rate according to the channel quality based on the reported CIR. Then, the packet is transmitted to the plurality of wireless communication terminal devices according to the scheduling.

FIG. 5A shows three wireless communication terminal devices A.
C shows the time change of CIR reported from C to C, and the curve 10 shows the CIR reported from the wireless communication terminal A,
The curve 20 is the CI reported from the wireless communication terminal B.
R and the curve 30 are C reported from the wireless communication terminal device C.
Each IR is shown. The base station device uses this CIR
The MCS for transmitting a packet is selected from among MCSs 1 to 6 having different modulation schemes and coding rates based on the above. The MCS1 is selected when the CIR is low, and is composed of the modulation method and the coding rate that give the lowest transmission rate.
6 is selected when the CIR is high, and is composed of a modulation method and a coding rate that maximizes the transmission rate. When transmitting a packet, the base station device selects the MCS having the highest transmission rate according to the reported CIR. Regarding the selection of the wireless communication terminal device that transmits the packet, for example, in the case of a scheduling algorithm such as round robin, the wireless communication terminal device A, the wireless communication terminal device B, and the wireless communication terminal device C transmit the packets in this order. Therefore, the packet is transmitted to each wireless communication terminal device by the MCS with the circled number in FIG. 5B.

[0004]

However, in the conventional downlink high-speed packet transmission method, when an MCS having a high transmission rate is selected and a packet is transmitted, the packet is transmitted at a predetermined packet error rate (PER). , Packet retransmission causes transmission delay,
For example, there is a problem that the quality is deteriorated when transmitting a packet such as a voice or moving image packet that requires real-time property.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wireless communication apparatus and a wireless communication method capable of improving the transmission quality of data that requires real-time processing.

[0006]

A wireless communication apparatus according to the present invention includes an acquisition unit for acquiring a required transmission rate required for transmitting data in real time, and an apparatus for transmitting data at the obtained required transmission rate. And a determining unit that determines the coding rate and the modulation method.

According to this structure, in order to determine the coding rate and the modulation method that satisfy the required transmission rate for transmitting data in real time, the maximum transmission rate that can be transmitted is determined from the conditions such as line quality. By transmitting data with a coding rate and a modulation method that result in a low transmission rate, the error rate of data transmission can be reduced and the occurrence of retransmission can be suppressed, and the delay of real-time application data can be suppressed and real-time application data can be suppressed. It is possible to improve the transmission quality of data required to be transmitted.

In the radio communication apparatus of the present invention, the deciding means decides a minimum coding rate and a modulation method that satisfy the acquired required transmission rate.

According to this structure, since the minimum coding rate and the modulation method satisfying the required transmission rate are determined, the transmission rate is lower than the maximum transmission rate determined by the conditions such as the line quality and the required transmission rate. By transmitting data at a coding rate and a modulation method that achieves a transmission rate that satisfies the transmission rate, it is possible to reduce the error rate of data transmission and suppress the occurrence of retransmission, and suppress the occurrence of delay in real-time application data. However, it is possible to improve the transmission quality of data that requires real-time processing.

The radio communication apparatus of the present invention has a configuration further comprising reporting means for reporting the coding rate and the modulation scheme determined by the determining means.

According to this structure, since the determined coding rate and modulation scheme are reported, the data from the data transmission source is reported by reporting the determined coding rate and modulation scheme to the data transmission source. In transmission, it is possible to reduce the error rate of data transmission and suppress the occurrence of retransmission, and suppress the occurrence of delay of real-time application data without changing the configuration of the data source,
It is possible to improve the transmission quality of data that requires real-time property.

[0012] The wireless communication apparatus of the present invention has a configuration further comprising a transmitting unit for transmitting data at the coding rate and the modulation method determined by the determining unit.

According to this structure, since the data is transmitted with the determined coding rate and modulation method, the data transmission source reduces the error rate of data transmission and suppresses the retransmission request from the data transmission destination. Therefore, it is possible to suppress the occurrence of delay of real-time application data and improve the transmission quality of data that requires real-time property.

A radio communication terminal apparatus of the present invention has a configuration having any one of the above radio communication apparatuses.

According to this structure, the same function and effect as those of the wireless communication device described above can be realized in the wireless communication terminal device.

A radio communication base station apparatus of the present invention has a configuration having any one of the above radio communication apparatuses.

According to this structure, the same operation and effect as those of the above-described wireless communication device can be realized in the wireless communication base station device.

The wireless communication method of the present invention comprises a step of acquiring a required transmission rate required for transmitting data in real time, an encoding rate and a modulation method for transmitting data at the obtained required transmission rate. And a determining step.

According to this method, in order to determine the coding rate and the modulation method that satisfy the required transmission rate for transmitting data in real time, the maximum transmittable transmission rate determined from the conditions such as the line quality is used. By transmitting data with a coding rate and a modulation method that result in a low transmission rate, the error rate of data transmission can be reduced and the occurrence of retransmission can be suppressed, and the delay of real-time application data can be suppressed and real-time application data can be suppressed. It is possible to improve the transmission quality of data required to be transmitted.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The essence of the present invention is that even when the wireless line condition is good and data can be transmitted at a high transmission rate,
That is, the data is transmitted at the minimum transmission rate that satisfies the required transmission rate of the transmitted data.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following, a downlink high-speed packet transmission method will be described as an example of data transmission.

FIG. 1 shows an IP according to an embodiment of the present invention.
It is a figure which shows an example of the wireless communication system containing a network. The wireless communication system shown in the figure includes a wireless communication terminal device 100, a base station device 200, and an IP network 30.
0, a fixed terminal device 400, and a server 500. Packets that are required to have real-time characteristics, such as voice and moving images, transmitted from the fixed terminal device 400 and the server 500 are received by the base station device 200 via the IP network 300, and the base station device 200 wirelessly communicates with the wireless communication terminal device 100. Wirelessly transmitted to.

FIG. 2 is a block diagram showing the configurations of radio communication terminal apparatus 100 and base station apparatus 200 in the above radio communication system.

In FIG. 2, the wireless communication terminal device 100 is shown.
Is an application unit 110, UDP (User Datagra
m Protocol) control unit 120, IP control unit 130, retransmission control unit 140, wireless transmission / reception unit 150, wireless resource control unit 160, line quality estimation unit 170, MCS (Modulation C)
oding scheme) selecting section 180 and multiplexing section 190.

The application section 110 is a real-time application section such as voice or moving picture. When transmitting real-time application data such as voice or moving picture, the application section 110 outputs the application data to the UDP control section 120. In addition, the application unit 110 notifies the MCS selection unit 180 of the required transmission rate required to transmit the real-time application data. UD
The P control unit 120 divides the data output from the application unit 110 into a predetermined size, adds a UDP header including a source port number, a destination port number, etc., and outputs the data to the IP control unit 130. . Further, the UDP control unit 120 removes the UDP header of the received data and then outputs the data to the application unit 110. I
The P control unit 130 adds an IP header including a source address and a destination address to the data output from the UDP control unit 120, and outputs the data to the multiplexing unit 190. Further, the IP control unit 130 removes the IP header of the received data and then outputs it to the UDP control unit 120. The retransmission control unit 140 divides the data output from the multiplexing unit 190 into a predetermined size at the time of data transmission, for example, CR
An error detection code such as C (Cyclic Redundancy Check) is added and output to the wireless transmission / reception unit 150. Further, the retransmission control unit 140 detects an error in the received packet by using an error detection code such as CRC at the time of receiving the data, and when there is no error, combines the predetermined packets and
Output to the control unit 130. At the time of data transmission, radio transmitting / receiving section 150 performs radio transmission processing such as encoding and modulation on transmission data, and then transmits the data via an antenna. Further, the wireless transmission / reception unit 150 performs wireless reception processing such as demodulation and decoding on the received data when receiving the data. The radio resource control unit 160 controls the retransmission control unit 140 and the radio transmission / reception unit 150. The channel quality estimation unit 170 estimates the wireless channel quality such as CIR from the pilot signal multiplexed on the wireless channel. The MCS selection unit 180 selects an MCS from the wireless channel quality estimation value estimated by the channel quality estimation unit 170 and the required transmission rate of the transmission data notified from the application unit 110 by a method described later. Multiplexing unit 190
Is the transmission data output from the IP control unit 130 and the MC
Information regarding the MCS selected by the S selection unit 180 is multiplexed.

On the other hand, the base station apparatus 200 includes a radio transmission / reception section 210, a retransmission control section 220, and a MAC (Medium Access Coordinate).
control unit 230, wireless resource control unit 240, I
The P control unit 250 and the link layer control unit 260 are included.

Radio transmitting / receiving section 210 performs a predetermined radio processing on a packet transmitted / received via an antenna.
During data transmission, retransmission control section 220 divides the data output from IP control section 250 into a predetermined size, adds an error detection code such as CRC, and outputs the data to radio transmission / reception section 210. In addition, the retransmission control unit 220
At the time of data reception, for example, an error detection code such as CRC is used to detect an error in the received data. If there is no error, a predetermined packet is combined and output to the IP control unit 250. The MAC control unit 230 is a wireless communication terminal that transmits data on a shared channel from information about MCS reported from a plurality of wireless communication terminal devices including the wireless communication terminal device 100 accommodated in the base station device 200 and a predetermined scheduling algorithm. Select a device. At this time, M reported from the selected wireless communication terminal device
Use CS. The wireless resource control unit 240 controls the retransmission control unit 220, the MAC control unit 230, and the wireless transmission / reception unit 210. The IP control unit 250 refers to the destination address of the packet sent from the link layer control unit 260 to determine the destination wireless communication terminal, and based on the result, determines whether or not the corresponding wireless communication terminal in the retransmission control unit 220 is Send data to the buffer. For received packets,
The packet is transmitted via the link layer control unit 260 to the transfer destination specified by the destination address in the IP header of the received packet. The link layer control unit 260 controls a wired link between the base station and the IP network, and exchanges packets with a fixed terminal device or a server (not shown).

Next, the operations of radio communication terminal apparatus 100 and base station apparatus 200 configured as described above will be explained with reference to FIG. Here, the operation from when the wireless communication terminal apparatus 100 receives the pilot signal to when the base station apparatus 200 transmits a packet sent from a fixed terminal apparatus or the like (not shown) to the wireless communication terminal apparatus 100 will be described. .

First, the data including the known pilot signal has a transmission mode of the retransmission control unit 2 of the base station apparatus 200.
After setting the transparent mode (the mode in which the destination is not specified and the retransmission is not performed) by the wireless communication unit 20, the wireless transmission / reception unit 210 sets, for example, CPICH (Common PIl).
ot CHannel) etc. are used for transmission.
The data including the transmitted pilot signal is received by the wireless transmission / reception unit 150 of the wireless communication terminal device 100,
Predetermined radio reception processing is performed and a pilot signal is output to channel quality estimation section 170.

Then, as shown in FIG. 3, the channel quality estimator 170 performs C based on the known pilot signal.
Channel quality such as IR is estimated (ST1000). The estimated line quality is notified to the MCS selection unit 180, and the required transmission rate for transmitting real-time application data is determined by the application unit 110.
Is notified to MCS selection section 180 (ST110
0). The notification of the required transmission rate may be performed only when the session of the application is started or only when the required transmission rate of the application is changed.

Then, the MCS selecting section 180 has an MCS (hereinafter, referred to as a coding rate) and a modulation method which have a coding rate and a modulation method which are the maximum transmission rate that can be transmitted in the notified channel quality.
"MCS1") is determined (ST1200).
Further, MCS selecting section 180 determines an MCS (hereinafter, referred to as “MCS2”) having a coding rate and a modulation scheme that is the lowest transmission rate that satisfies the notified required transmission rate (ST1300). Then, the MCS selecting section 180 compares the sizes of MCS1 and MCS2 (ST1400), and if MCS1 is larger,
MCS2 is selected as the MCS for transmitting data (ST1500). On the other hand, when the MCS1 is smaller, the line quality is poor and the data cannot be transmitted by the MCS having the coding rate and the modulation scheme that satisfy the required transmission rate. Therefore, for example, the data transmission from the base station apparatus 200 to the wireless communication terminal apparatus 100 is performed. Scheduling is changed so that the number of times of allocation is increased (ST1600).

When the MCS1 is larger, the MCS2 having the minimum transmission rate satisfying the required transmission rate is selected even if the line quality is good, and the selected MCS2 is selected.
The information regarding the output is output to the multiplexing unit 190. And
The multiplexing unit 190 multiplexes the transmission data with information about the MCS2, and the wireless transmission / reception unit 150 performs predetermined wireless transmission processing and then transmits the information via the antenna.

The transmission data is received by the wireless transmission / reception unit 210 of the base station apparatus 200 via the antenna, and the information about the multiplexed MCS2 is the MAC control unit 23.
0 is notified. Then, the MAC control unit 230 causes the wireless communication terminal device 10 accommodated in the base station device 200.
MCS reported from a plurality of wireless communication terminal devices including 0
Information and a predetermined scheduling algorithm, a wireless communication terminal device that is a partner station that transmits data using a shared channel shared by a plurality of wireless communication terminal devices is selected, and information on the selected wireless communication terminal measures is Is notified to the retransmission control unit 220, and
The MCS information reported from the wireless communication terminal device is
The wireless transmission / reception unit 210 is notified. Here, the wireless communication terminal device 100 is selected as a partner station to which data is transmitted, and the information of the wireless communication terminal device 100 is retransmitted by the retransmission control unit 220.
M notified to the user and reported from the wireless communication terminal device 100.
It is assumed that the wireless transmission / reception unit 210 is notified of information regarding CS2.

When data is transmitted from the base station device 200 to the wireless communication terminal device 100, the transmission data is
The wireless transmission / reception unit 210 encodes and modulates with the coding rate and modulation method of MCS2, and transmits to the wireless communication terminal apparatus 100 by using the shared channel via the antenna. At this time, M of the transmission data
Since the MCS2 is used as the CS, the coding rate and the modulation method that achieve the minimum transmission rate that satisfies the required transmission rate of the data to be transmitted are used, and the error rate in wireless communication can be reduced. it can.

FIG. 4 is a diagram showing an example of the relationship between the channel quality and the data error rate in a plurality of MCSs. In FIG. 4, the horizontal axis indicates the CIR which is the line quality,
The vertical axis represents the PER (Packet Error Rate) which is the error rate when transmitting packet data. A curve 610 shows the relationship between CIR and PER in the MCS having the highest transmission rate, and a curve 620 shows CIR and P in the MCS having the second highest transmission rate.
The curve 630 shows the relationship between CIR and PER at the third highest MCS as the transmission rate, and the curve 640 shows the relationship between CIR and PER at the lowest MCS as the transmission rate. There is.

When the CIR estimated by the channel quality estimation unit 170 of the wireless communication terminal apparatus 100 is a value of A or less, the PER of the packet to be transmitted is set to a curve 640 so that the PER of the packet is equal to or less than a predetermined target value T. MCS shown is MCS
1 is selected by the MCS selection unit 180, and similarly, when the CIR is A or more and B or less, the MCS indicated by the curve 630 is selected as MCS1 and the CIR is B.
If it is greater than or equal to C, then the MCS represented by curve 620 is selected as MCS1, and if the CIR is greater than or equal to C, then the MCS represented by curve 610 is MCS.
Selected as 1.

Here, when the CIR estimated by the channel quality estimating section 170 is x, the MCS selecting section 180
Selects the MCS indicated by the curve 620 as MCS1 that can transmit packets at the maximum transmission rate while satisfying the target value T of PER. On the other hand, assuming that the MCS indicated by the curve 630 is selected by the MCS selection unit 180 as the MCS2 satisfying the required transmission rate for transmitting the real-time application data, the information about this MCS2 is reported to the base station apparatus 200. Then, the base station device 200 receives the reported M
A packet for the wireless communication terminal device 100 is transmitted by CS2. As a result, the PER can be reduced by P _{x as} compared with the case where MCS1 is selected.

As described above, according to the present embodiment, the wireless communication terminal apparatus estimates the wireless channel quality, determines the MCS that is the highest transferable rate in the estimated wireless channel quality, and at the same time. , Determining the MCS that is the minimum transmission rate that satisfies the required transmission rate of the data to be transmitted, and if the MCS based on the required transmission rate is lower as the transmission rate, reports the information regarding the MCS, and the base station device Since the data is transmitted by the reported MCS, it is possible to reduce the error rate in the data transmission without changing the configuration of the base station device, and reduce the occurrence of retransmission even when transmitting the real-time application data. As a result, it is possible to suppress the occurrence of data delay and improve the transmission quality of packets that require real-time processing. Door can be.

In the present embodiment, the minimum MCS that satisfies the required transmission rate is selected in the wireless communication terminal apparatus, but the wireless communication terminal apparatus transmits the line quality and the required transmission rate to the base station apparatus. The base station apparatus may be configured to report and select the minimum MCS that satisfies the required transmission rate based on the channel quality and the required transmission rate.

[0040]

As described above, according to the present invention,
It is possible to improve the transmission quality of packets that require real-time processing.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a configuration of a wireless communication system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing configurations of a wireless communication terminal apparatus and a base station apparatus according to one embodiment.

FIG. 3 is a flowchart showing an MCS selection operation according to one embodiment.

FIG. 4 is a diagram showing an example of a relationship between channel quality and data error rate according to an embodiment.

FIG. 5 is a diagram for explaining data transmission by conventional MCS selection.

[Explanation of symbols]

110 Application Department 120 UDP control unit 130, 250 IP controller 140, 220 retransmission control unit 150, 210 Wireless transceiver 160, 240 Radio resource control unit 170 Channel quality estimation unit 180 MCS selector 190 Multiplexer 230 MAC control unit 260 link layer control unit

Continued front page    (72) Inventor Yuji Oie             3-8-19 Aoyama, Dazaifu City, Fukuoka Prefecture (72) Inventor Hiroyuki Koga             950-2 Nakazai, Iizuka City, Fukuoka Prefecture (72) Inventor Takahiro Shoji             3-1, Tsunashima-Higashi 4-chome, Kohoku-ku, Yokohama-shi, Kanagawa             Matsushita Communication Industry Co., Ltd. (72) Inventor Osamu Kato             3-1, Tsunashima-Higashi 4-chome, Kohoku-ku, Yokohama-shi, Kanagawa             Matsushita Communication Industry Co., Ltd. F-term (reference) 5K030 GA11 HA08 HB01 HB02 JL01                       JT01 JT04 JT09 KA19 LA07                 5K067 AA21 AA23 BB02 BB21 CC08                       DD11 DD51 EE02 EE10 EE16                       FF02

Claims (7)

[Claims] 1. An acquisition unit for acquiring a required transmission rate required for transmitting data in real time, and a determining unit for determining a coding rate and a modulation method for transmitting data at the obtained required transmission rate. A wireless communication device comprising: 2. The wireless communication apparatus according to claim 1, wherein the determining unit determines a minimum coding rate and a modulation scheme that satisfy the acquired required transmission rate. 3. The wireless communication apparatus according to claim 1, further comprising reporting means for reporting the coding rate and the modulation scheme determined by the determining means. 4. The wireless communication apparatus according to claim 1, further comprising a transmitting unit that transmits data at the coding rate and the modulation scheme determined by the determining unit. 5. A wireless communication terminal device comprising the wireless communication device according to claim 1. Description: 6. A wireless communication base station device comprising the wireless communication device according to claim 1, claim 2, or claim 4. 7. A step of obtaining a required transmission rate for transmitting data in real time, and a step of determining a coding rate and a modulation method for transmitting data at the obtained required transmission rate. A wireless communication method comprising.