JP5239477B2 - Radio base station apparatus and communication method thereof - Google Patents

Description

  The present invention relates to a radio communication system, and more particularly to a radio packet communication using a TCP and a radio base station apparatus.

  The importance of mobile communications has increased and the demand for data transfer over wireless connections has also increased. However, the bandwidth of wireless communication lines is scarce and is a limited resource. In addition, there is a possibility that the bandwidth fluctuates at a high speed due to a fading drop or shadowing. Particularly for an application using TCP (Transmission Control Protocol) as a transport protocol, a negative result may be brought about. For example, when a long delay occurs in a wireless communication circuit, a TCP congestion avoidance mechanism is activated, so that the bandwidth becomes narrower and the end user can enjoy only low performance. Therefore, there are many advantages if the available radio resources can be used efficiently.

  As a conventional technique for efficiently using radio resources in an application using TCP, for example, a technique described in Patent Document 1 is known. A conventional radio base station apparatus will be described with reference to FIG. 1 and FIG.

  FIG. 1 shows the overall configuration of a wireless communication system. This system includes a radio base station apparatus 900, a mobile station apparatus 200, an upper layer processing apparatus 300 connected to the radio base station apparatus 900, a network 400, and a server 500. A TCP processing unit exists in the server 500, and an application program operates. A session is set between the mobile station apparatus 200 and the server 500 via the wireless base station apparatus 900 by TCP. When the mobile station apparatus 200 receives information from the server 500, the mobile station apparatus returns an acknowledgment (reception notification) to indicate reception quality. At that time, the transmission / reception processing unit 250 inside the mobile station apparatus 200 converts the acknowledgment into a high-frequency signal and transmits it to the radio base station apparatus 900.

  FIG. 6 shows the internal structure of a conventional radio base station apparatus 900. In FIG. 6, a radio frequency signal received by an antenna 901 is converted into a baseband band received signal s902 in a radio unit 902. The demodulator 903 has a function of demodulating uplink data channel data from s902 and calculating a soft decision value s903a. The demodulation function includes despreading on received data and calculation for demodulating a complex signal into soft decision data. The demodulator 903 also has a function of calculating uplink control channel data s903b from the received signal s902. The uplink data channel decoding unit 904 and the uplink control channel decoding unit 905 have a function of performing error correction decoding on s903a and s903b, respectively. The uplink data channel decoding unit 904 is configured by, for example, a turbo decoder, and the uplink control channel decoding unit 905 is configured by, for example, a Viterbi decoder of a convolutional code. During the operation of the uplink data channel decoding unit 904, the decoding result s905b of the uplink control channel decoding unit 905 is used.

  Outputs s904 and s905a from the uplink data channel decoding unit 904 and the uplink control channel decoding unit 905 are output to the MAC conversion unit 906 and the scheduler 911, respectively. Of these, s904 is data called a PDU (Protocol Data Unit) and having a size matching the data amount of the wireless section. The MAC conversion unit 906 has a function of assembling a MAC frame by concatenating or dividing PDUs for each radio frame. The MAC frame is output to the upper layer processing apparatus 300.

  The scheduler 911 is based on downlink CQI (Channel Quality Indicator) information included in the uplink channel decoding result s905a and the data accumulation amount s912b in the input buffer 912 in the radio frame at the time when the data flows into the scheduler 911. The downlink radio resource to be allocated to the mobile station apparatus is determined and notified to the downlink data channel coding unit 914 through s911c. For the CQI information, for example, an average value of SIR (Signal to Interference Ratio) is used.

  The scheduler 911 has a function of outputting the downlink data channel coding information to the downlink control channel coding unit 913 by s911b. The downlink data channel encoding unit 914 has a function of performing error correction encoding of the downlink control channel and the downlink data channel by using s911b as the downlink data channel encoding information. The encoded data s913 and s914 are input to the modulation unit 915. Based on the control information s911a from the scheduler 911, the modulation unit 915 has a function of allocating each channel in the downlink transmission signal to a frequency resource to form a transmission signal. The functions include modulation coding and spreading processing. Output data s915 from the modulation unit 915 is output to the radio unit 902, converted into a high frequency signal, and then transmitted from the antenna 901.

  The input buffer 912 has a function of accumulating data coming from the higher layer processing apparatus 300 for each radio frame. The input buffer 912 includes a control device having the following functions (1) and (2). That is, (1) a function of outputting the accumulated data in the buffer 912 to the PDU conversion unit 916 for each radio frame, and (2) a function of notifying the scheduler 911 of the accumulated data amount in the buffer by s912b for each radio frame. is there.

  The PDU conversion unit 916 has a function of converting a MAC frame into a PDU.

Next, the operation of a radio communication system including the above-described conventional radio base station apparatus 900 will be described.
When the mobile station apparatus 200 transmits a data transmission request to the radio base station apparatus 900, the radio base station apparatus 900 receives the request and transmits the received request to the server 500 via the upper layer 300 and the network 400. . When receiving the request, the server 500 transmits the requested object or file to the radio base station apparatus 900. When receiving the requested object or file, the radio base station apparatus 900 stores the requested object or file in the input buffer 912, and transmits the acknowledgment to the server 500, thereby receiving the server 500. To be notified. By doing so, the risk that the TCP congestion control mechanism is used can be reduced. The object or file stored in the input buffer 912 is transmitted to the mobile station apparatus 200 under the control of the scheduler 911.
JP-T-2006-503493

  However, in a communication system using a conventional radio base station apparatus, if the transmission rate in the downlink radio section continues to exceed the reception processing rate of the application program 270, the movement immediately after the transmission rate exceeds the reception processing rate. The station apparatus 200 reduces the window size (the size of a packet that can be transferred at one time without receiving an acknowledgment) in the TCP segment to be transmitted, and controls the amount of downlink data. Here, since the TCP segment reaches the application on the radio base station side and it takes a long time to reduce the amount of downlink data, there is a problem that the TCP buffer overflow on the mobile station apparatus side easily occurs. When the TCP buffer overflow occurs, the TCP segment transmitted in the downlink is lost, so that the TCP segment is retransmitted, resulting in a decrease in throughput and a data delay.

  The time until the downlink data amount is reduced is that the remaining TCP buffer in the TCP processing unit 260 on the mobile station apparatus side is placed on the TCP segment as a window size, and the base station starts from the time when uplink transmission is performed. This is the time it takes for data transmitted from the server TCP processing unit to reach the wireless base station device 900 once it reaches the server 500 via the station device 900.

  The present invention has been made in view of the above points, and an object of the present invention is to shorten the elapsed time from the reduction of the TCP window size to the reduction of the downlink data amount in the mobile station apparatus, and to retransmit the TCP segment. An object of the present invention is to provide a radio base station apparatus that prevents generation, throughput reduction, and data delay.

In order to achieve the above object, the present invention can transfer data received from a server to a client via a wireless communication line by a transport protocol at a time without receiving a reception notification. Parameter extraction means for extracting a parameter related to the packet size from information received from the client, storage means for storing the number of allowable occupied resource blocks corresponding to the parameter, the extracted parameter, and the storage means Instructing means for determining the number of allowable occupied resource blocks at the time of data transmission based on the relationship between the parameter and the number of allowable occupied resource blocks at the time and instructing data transmission with the number of allowable occupied resource blocks as the number of occupied resource blocks at the time of data transmission It is characterized by comprising.

Further, the present invention provides a parameter related to a packet size that can be transferred at a time without receiving a reception notification in a wireless base station device that transfers data received from a server to a client via a wireless communication line by a transport protocol. Extracting from the information received from the client, instruction means for instructing data transmission based on the extracted parameter, a buffer for accumulating data received from the server, a control device, And the controller is configured to output the data accumulated in the buffer and stop outputting the data accumulated in the buffer when a stop instruction is received from the instruction means. A function for accumulating data received from the server, and a data accumulated in the buffer. A function for measuring the amount of data, and a function for notifying the instruction means of the data amount, wherein the instruction means is a required resource block required for transmitting the data amount notified from the control device. The number is calculated, the allowable occupied resource block number at the time of data transmission is compared with the required resource block number, and if the required resource block number exceeds the allowable occupied resource block number at the time of data transmission, the required A data transmission instruction is performed using the number of resource blocks as the number of occupied resource blocks during data transmission .

Further, the present invention is a communication method in a radio base station apparatus for transferring data received from a server to a client via a radio communication line by a transport protocol, and the parameter extraction means of the radio base station apparatus includes: A parameter related to a packet size that can be transferred at a time without receiving a reception notification is extracted from information received from the client, and the instruction unit of the radio base station apparatus stores the number of allowable occupied resource blocks according to the parameter Based on the relationship between the parameter in the storage means and the number of allowed occupied resource blocks and the extracted parameter, the number of allowed occupied resource blocks at the time of data transmission is determined, and the number of allowed occupied resource blocks is the number of occupied resource blocks at the time of data transmission. A data transmission instruction is performed as follows.

  According to the present invention, the window size of the TCP buffer on the mobile station device side can be grasped in the radio base station device, and the amount of data transmitted from the radio base station device is controlled using the window size. Compared with the prior art, the amount of data to be transmitted can be controlled in a short time. Therefore, even when the downlink data rate in the radio section exceeds the application processing rate on the mobile station device side, the probability of the TCP buffer overflow on the mobile station device side can be reduced, and the loss of the TCP segment and the accompanying retransmission and delay are avoided. can do.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an overall configuration diagram showing an embodiment of a radio communication system in which a radio base station apparatus of the present invention is used. This system includes a radio base station apparatus 100, a mobile station apparatus 200, an upper layer 300 connected to the radio base station apparatus 100, a network 400, and a server 500. A TCP processing unit exists in the server 500, and an application program operates. A session is set between the mobile station apparatus 200 and the server 500 via the wireless base station apparatus 100 by TCP. When the mobile station apparatus 200 receives information from the server 500, the mobile station apparatus returns an acknowledgment to indicate reception quality. At that time, the transmission / reception processing unit 250 inside the mobile station apparatus 200 converts the acknowledgment into a high-frequency signal and transmits it to the radio base station apparatus 100.

  FIG. 2 shows an internal structure of the radio base station apparatus 100 as an embodiment of the present invention. In FIG. 2, the radio frequency signal received by the antenna 101 is converted by the radio unit 102 into a received signal s102 in the baseband. The demodulator 103 has a function of demodulating uplink data channel data from s102 and calculating a soft decision value s103a. The demodulation function includes despreading on received data and calculation for demodulating a complex signal into soft decision data. The demodulator 103 also has a function of calculating uplink control channel data s103b from the received signal s102. Uplink data channel decoding section 104 and uplink control channel decoding section 105 have a function of performing error correction decoding on s103a and s103b, respectively. The uplink data channel decoding unit 104 is configured by, for example, a turbo decoder, and the uplink control channel decoding unit 105 is configured by, for example, a Viterbi decoder of a convolutional code. During the operation of the uplink data channel decoding unit 104, the decoding result s105b of the uplink control channel decoding unit 105 is used.

  Outputs s104 and s105a from uplink data channel decoding section 104 and uplink control channel decoding section 105 are output to MAC conversion section 106 and scheduler 111 (instruction means), respectively. Of these, s104 is generally called PDU and is data having a size matching the data amount of the wireless section. The MAC conversion unit 106 has a function of assembling a MAC frame by concatenating or dividing PDUs for each radio frame. The MAC frame is output to the upper layer processing apparatus 300 and the TCP window extraction unit 110 (parameter extraction means). The TCP window extraction unit 110 has a function of extracting window size information from the MAC frame s106 based on the format of FIG. In FIG. 3, the value in parentheses is the number of bytes. Returning to FIG. 2, the TCP window extraction unit 110 outputs the window size s 110 to the scheduler 111.

  The scheduler 111 is based on the downlink CQI information included in the uplink channel decoding result s105a, the TCP window size s110, and the data accumulation amount s112b in the input buffer 112 in the radio frame at the time when the data flows into the scheduler 111. The downlink radio resource to be allocated to is determined and notified to the downlink data channel encoding unit 114 by s111c. For the CQI information, for example, an average value of SIR is used.

  In addition, a scheduler (storage means) is provided that is attached to the scheduler 111 and stores the relationship between the window size W and the allowable occupied RB (Resource Block) number in FIG. The scheduler 111 has a function of determining the maximum value of radio resources to be allocated to the mobile station apparatus based on the relationship between the window size W stored in the memory and the allowable occupied RB number. Here, the allowable number of occupied RBs is the frequency bandwidth of the transmission signal to the mobile station apparatus to be transmitted. The larger the value, the higher the transmission rate in the wireless section. In FIG. 4, if the window size W is not less than 0 and less than W0, the allowable occupied RB count is set to 0 in the radio frame. That is, the downlink data channel is not transmitted. If the window size W is greater than or equal to W0 and less than W1, the allowable occupied RB number is increased according to the window size W, and the occupied RB number is determined within a range smaller than the occupied RB number. If the window size W is equal to or greater than W1, the number of occupied RBs is not limited to the maximum value that can be assigned as the number of occupied RBs. The values of W0 and W1 are adjusted to appropriate values according to W_MAX (the maximum value of the TCP window size on the mobile station apparatus side).

  Returning to FIG. 2, the scheduler 111 also has a function of outputting to the input buffer 112 an instruction to stop outputting data to the downlink data channel encoding unit 114 by s 111 d. The stop instruction is an instruction to accumulate the difference in the input buffer 112 when the data amount of the MAC frame s120 that has flowed in from the upper layer in the current wireless frame exceeds the number of occupied RBs.

  The scheduler 111 has a function of outputting the downlink data channel coding information to the downlink control channel coding unit 113 by s111b. The downlink control channel encoding unit 113 and the downlink data channel encoding unit 114 have a function of performing error correction encoding of the downlink control channel and the downlink data channel, respectively. The encoded data s113 and s114 are input to the modulation unit 115. Based on the control information s111a from the scheduler 111, the modulation unit 115 has a function of allocating each channel in the downlink transmission signal to a frequency resource to form a transmission signal. The functions include modulation coding and spreading processing. Output data s115 from the modulation unit 115 is output to the radio unit 102, converted into a high-frequency signal, and then transmitted from the antenna 101.

  Note that the scheduler 111 may have a function of limiting the modulation scheme and coding rate in addition to the function of determining the allowable occupied RB count. That is, it is a function for obtaining an allowable range of a method to be used and a value, and setting radio parameters within the range.

  The input buffer 112 has a function of accumulating data coming from the upper layer processing apparatus 300 for each radio frame. A control device attached to the input buffer 112 and having the following functions (1) to (4) is provided. That is, (1) a function of measuring the amount of data stored in the input buffer 112 at a time after the data coming from the upper layer processing apparatus 300 flows for each radio frame, and (2) the buffer 112 for each radio frame. A function for notifying the amount of stored data to the scheduler 111 by s112b, (3) a function for outputting the stored data in the buffer 112 to the PDU conversion unit 116 for each radio frame, and (4) for each radio frame by the scheduler 111 to s111d. When receiving a stop instruction, the function stores the data after the instruction reception time in the input buffer 112 without outputting the data to the PDU conversion unit 116.

  The PDU conversion unit 116 has a function of converting a MAC frame into a PDU.

Next, the operation of the radio communication system including the radio base station apparatus 100 described above will be described.
When mobile station apparatus 200 transmits a data transmission request to radio base station apparatus 100, radio base station apparatus 100 receives the data transmission request. Then, the received data transmission request is transmitted to the server 500 via the upper layer 300 and the network 400. When receiving the data transmission request, the server 500 transmits the requested object or file to the radio base station apparatus 100. After receiving the requested object or file, the radio base station apparatus 100 stores the object or file in the input buffer 112 and transmits an acknowledgment to the server 500. This notifies the server 500 that the object or file has been received. By doing so, the risk that the TCP congestion control mechanism is used can be reduced. The object or file stored in the input buffer 112 is transmitted to the mobile station apparatus 200 under the control of the scheduler 111.

FIG. 5 is a flowchart showing the operation of the radio base station apparatus 100.
First, the TCP window extraction unit 110 extracts the window size W from the MAC frame s106 (step S1). Next, the scheduler 111 obtains the allowable occupied RB number (hereinafter referred to as the allowable RB number) from W (step S2). Specifically, as described above, if W is 0 or more and less than W0 in FIG. 4, the allowable RB number is set to 0 in the radio frame. If W is greater than or equal to W0 and less than W1, the allowable RB number is increased according to W, and the allowable RB number is determined within a range smaller than the occupied RB number. If W is greater than or equal to W1, the allowable RB number does not limit the maximum value that can be assigned as the occupied RB number.

  The scheduler 111 also obtains the number of RBs required to transmit Q from the buffer data accumulation amount Q reported by the control device of the input buffer 112 (hereinafter referred to as the required number of RBs) (step S2). Specifically, Q is divided by the amount of data that can be transmitted by one RB number, and a value obtained by rounding up the decimal point is set as the required RB number.

  Next, the scheduler 111 compares the required RB number with the allowable RB number (step S3). If the required RB count exceeds the allowable RB count, the scheduler 111 performs rewriting so as to use the allowable RB count as the required RB count (step S4).

  Next, when the control device of the input buffer 112 outputs to the PDU conversion unit 116 the amount of data that can be transmitted using the required number of RBs, the scheduler 111 outputs the output from the input buffer 112 to the control device. An instruction to stop is given (step S5). This process means that, of the transmission data that has flowed into the input buffer 112, data surplus from the transmittable data amount is accumulated. The amount of data in the input buffer 112 increases until the time when the TCP processing unit existing in the server 500 in FIG. 1 recognizes the decrease in the window size and the amount of data flowing into the input buffer 112 in FIG. 2 decreases. After that, if the window size increases again, the scheduler 111 allocates a wider band radio resource, so that the amount of data stored in the input buffer 112 decreases.

  Next, the downlink data channel encoder 114 and the modulator 115 are notified that the number of occupied RBs of radio resources used by the downlink data channel is the required number of RBs (step S6). Then, using the required number of RBs, downlink data channel encoding section 114 encodes the data flowing from input buffer 112 to form s113, and outputs the result to modulation section 115. Modulation section 115 forms output data s115 from downlink data channel encoded data s114 and downlink control channel encoded data s113, and outputs this to radio section 102. As a result, a radio frequency signal s101 is output from the radio unit 102, and data is transmitted from the antenna 101 to the mobile station apparatus 200.

  As described above, according to the present embodiment, the TCP window extraction unit 110 is provided in the radio base station apparatus 100 so that the window size W of the TCP buffer on the mobile station apparatus side can be grasped. Thus, the amount of data transmitted from the radio base station apparatus 100 is controlled. As a result, even when the downlink data rate in the radio section exceeds the application processing rate on the mobile station device side, the data amount corresponding to the window size is transmitted at the time when the radio base station device 100 receives the acknowledgement. The probability of TCP buffer overflow on the mobile station apparatus side can be reduced, and loss of TCP segments and accompanying retransmissions and delays can be avoided.

  As described above, the embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the scope of the present invention. It is possible to

It is a block diagram which shows the whole structure of the radio | wireless communications system containing a radio base station apparatus. It is a block diagram which shows the structure of the radio base station apparatus by one Embodiment of this invention. It is a figure which shows the format of a TCP header. It is a figure which shows the relationship between window size W and the number of allowable occupation RBs. It is a flowchart explaining operation | movement of a scheduler. It is a block diagram which shows the structure of the conventional radio base station apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100, 900 ... Wireless base station apparatus 101, 901 ... Antenna 102, 902 ... Radio | wireless part 103, 903 ... Demodulator 104, 904 ... Uplink data channel decoding part 105, 905 ... Uplink control channel decoding part 106, 906 ... MAC conversion part DESCRIPTION OF SYMBOLS 110 ... TCP window extraction part 111,911 ... Scheduler 112,912 ... Input buffer 113,913 ... Downlink control channel encoding part 114,914 ... Downlink data channel encoding part 115,915 ... Modulation part 116,916 ... PDU conversion part DESCRIPTION OF SYMBOLS 200 ... Mobile station apparatus 250 ... Transmission / reception processing part 260 ... TCP processing part 270 ... Application program 300 ... Upper layer processing apparatus 400 ... Network 500 ... Server s101, s901 ... High frequency signal s102, s902 ... Reception data s103a, s9 3a ... soft decision value s103b, s903b ... uplink control channel data s104, s904 ... PDU
s105a, s105b, s905a, s905b Uplink control channel decoding result s106, s906 ... MAC frame s110 ... Window size s111a, s911a ... Transmission signal formation control s111b, s911b ... Downlink data channel coding information writing control s111c, s911c ... To mobile station apparatus Value of radio resource to be allocated s111d ... data output control s112a, s912a ... data s112b, s912b ... accumulated data amount in buffer s113, s913 ... data after downlink control channel encoding s114, s914 ... data after downlink data channel encoding s115, s915 ... Output data s116, s916 ... PDU
s120, s920 ... MAC frame

Claims (8)

In a wireless base station device that transfers data received from a server to a client via a wireless communication line by a transport protocol,
A parameter extracting means for extracting, from the information received from the client, a parameter related to a packet size that can be transferred at one time without receiving a reception notification;
Storage means for storing the number of allowable occupied resource blocks according to the parameter;
Based on the extracted parameters , the relationship between the parameters in the storage means and the number of allowable occupied resource blocks, the number of allowable occupied resource blocks at the time of data transmission is determined, and the number of allowable occupied resource blocks is determined as the occupied resource at the time of data transmission An instruction means for instructing data transmission as the number of blocks ;
A radio base station apparatus comprising:   The radio base station apparatus according to claim 1, wherein the transport protocol is TCP.   The radio base station apparatus according to claim 2, wherein the parameter is a window size in TCP. The radio base station apparatus according to any one of claims 1 to 3 , further comprising a buffer that accumulates data received from the server. A control device,
The control device has a function of outputting data stored in the buffer;
A function of stopping output of data stored in the buffer when a stop instruction is received from the instruction means, and storing data received from the server in the buffer;
A function of measuring the amount of data stored in the buffer;
A function of notifying the instruction means of the data amount;
The radio base station apparatus according to claim 4, further comprising: The instructing means calculates the number of required resource blocks required for transmitting the data amount notified from the control device,
Compare the number of allowable occupied resource blocks at the time of data transmission and the required number of resource blocks,
When the required resource block number exceeds the allowable occupied resource block number at the time of data transmission,
The radio base station apparatus according to claim 5 , wherein a data transmission instruction is performed with the number of required resource blocks as the number of occupied resource blocks at the time of data transmission.   In a wireless base station device that transfers data received from a server to a client via a wireless communication line by a transport protocol,
  A parameter extracting means for extracting, from the information received from the client, a parameter related to a packet size that can be transferred at one time without receiving a reception notification;
  Instruction means for instructing data transmission based on the extracted parameters;
  A buffer for accumulating data received from the server;
  A control device;
  Comprising
  The control device has a function of outputting data stored in the buffer;
  A function of stopping output of data stored in the buffer when a stop instruction is received from the instruction means, and storing data received from the server in the buffer;
  A function of measuring the amount of data stored in the buffer;
  A function of notifying the instruction means of the data amount;
  Comprising
  The instructing means calculates the number of required resource blocks required for transmitting the data amount notified from the control device,
  Compare the number of allowable occupied resource blocks at the time of data transmission and the required number of resource blocks,
  When the required resource block number exceeds the allowable occupied resource block number at the time of data transmission,
  A data transmission instruction is made with the required number of resource blocks as the number of occupied resource blocks during data transmission.
  A radio base station apparatus. A communication method in a radio base station apparatus for transferring data received from a server to a client via a radio communication line by a transport protocol,
The parameter extraction means of the radio base station apparatus extracts parameters related to a packet size that can be transferred at a time without receiving a reception notification from information received from a client,
The instructing means of the radio base station apparatus is configured to allow for data transmission based on the relationship between the parameter in the storage means for storing the allowable occupied resource block number corresponding to the parameter and the allowable occupied resource block number and the extracted parameter A communication method characterized in that the number of occupied resource blocks is determined, and a data transmission instruction is performed with the allowable number of occupied resource blocks as the number of occupied resource blocks during data transmission .

Images