JP2008035366A - Method of communication between radio base station and radio network controller, radio base station, and radio network controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow the variation of the propagation speed in a wired section to follow up the variation of the propagation speed in a radio section of a radio communication system. <P>SOLUTION: A control Cell generator 62 sends a controlling ATM cell having required speed information of each communication channel multiplexed with a channel identification signal to a radio network controller 52. A control Cell generator 63 of the radio network controller 52 acquires required speed information of a wired line of each channel. A speed decision/assembly processor 64 and a data signal assembly processor control the transmission speed of data on each channel of the wired line, based on the output interval and the PDU number of each channel. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a communication method, a radio base station, and a radio network control device in a radio communication system including a radio terminal device, a radio base station, and a radio network control device.

  HSDPA (High Speed Downlink Packet Access) is adopted as a communication method of a wireless communication system such as a mobile phone. HSDPA realizes high-speed wireless communication by adaptively switching the coded modulation system according to the wireless environment between the wireless base station and the wireless terminal. Specifically, when the reception condition is poor, select a stable but slow QPSK (Quadrature Phase Shift Keying) modulation method and a coding method with large error correction capability.When the reception condition is good, a faster 16QAM (16 Quadrature Amplitude Modulation) Select a modulation method and a coding method with a small error correction capability. In HSDPA, the wireless transmission rate is changed in the range of 0 to 14 Mbps every 2 ms according to the wireless environment of the wireless terminal.

  Patent Document 1 discloses that in a mobile communication environment in which a radio band allocated to a mobile device is dynamically changed, high throughput can be obtained by quickly controlling the data transmission speed of the transmitter in accordance with the change of the radio band. Is described. Specifically, when communication is performed using TCP (Transmission Control Protocol), identification information (for example, a sequence number of a TCP segment) of a data unit transmitted from the base station to the mobile device is notified to the transmitter. The transmitter estimates the TCP segment retention amount in the base station from the sequence number of the TCP segment that has been transmitted to the mobile device, and controls the transmission speed of the TCP segment according to the estimated retention amount.

  Patent Document 2 describes that in a communication device that relays ATM cells, a plurality of flows having a specific attribute are grouped and flow control is performed in units of groups.

  Here, FIG. 17 shows a conventional wireless communication system that uses ATM cells to transmit data in a wired section between a wireless base station (BTS) 11 and a wireless network controller (RNC) 12. To explain.

This wireless communication system includes a wireless base station 11 that transmits and receives wireless signals to and from the wireless terminal 13 and a wireless network control device 12 that is connected to the network 14.
The radio base station 11 includes a buffer 21 that stores voice signals and the like of a plurality of communication channels, a radio state determination unit 22 that determines a radio state of the radio terminal 13, a scheduling unit 23 that controls a read schedule of the buffer 21, And a coding unit 24 that converts the signal read from the buffer 21 into a radio signal of a predetermined modulation scheme and coding scheme and transmits the radio signal.

  In addition, the radio base station 11 includes a flow control unit 25 that performs flow control for controlling the communication speed of the wired section for each channel based on buffer information indicating the data retention state of the buffer 21, radio status information, and scheduling information; A control cell generating unit 26 that generates a control ATM cell including required speed information of a wired section for each channel is provided.

  The wireless network control device 12 determines the communication speed based on the control cell receiver 27 that receives the control ATM cell and the requested speed information of the control ATM Cell, and determines the speed for instructing the assembly of the ATM cell for the data signal An assembly processing unit 28 and a data signal assembly processing unit 29 that transmits ATM cells at a communication speed instructed by the speed determination / assembly processing unit 28.

Here, a method for controlling the communication speed in the wired section of the conventional wireless communication system will be described.
The flow control unit 25 of the radio base station 11 outputs the requested speed information of each communication channel to the control cell generation unit 26 as a control signal. The control cell generator 26 multiplexes a control signal (requested speed information), an ATM header (Header), a channel (CH) header, and an SC header to generate a control ATM cell for each channel to generate a radio network controller. 12 to send.

  FIG. 18 is a diagram showing a format of a conventional control ATM cell. The control ATM cell 31 includes a 5-byte ATM header, a 3-byte SC header, a 3-byte channel header for channel identification, a 5-byte control signal, and a 37-byte spare area.

  The control cell receiver 27 of the radio network controller 12 filters the channel header of the control ATM cell 31 and the ATM header to extract the control ATM cell of the specific channel and obtains the requested rate information of the specific channel. To do.

  The speed determination / assembly processing unit 28 determines the required speed of each channel and instructs the data signal assembly processing unit 29 about the data transmission speed. The data signal assembly processing unit 29 transmits data to the radio base station 11 at the instructed communication speed.

  By the way, in the wireless communication system of the HSDPA system, the wireless transmission speed changes in the range of 0 to 14 Mbps according to the wireless environment of the wireless terminal. Therefore, transmission of data in the wired section between the wireless network control device 12 and the wireless base station 11 is performed. If the speed is not changed according to the transmission speed of the wireless section, a signal flows into the buffer 21 of the wireless base station 11 at a speed equal to or higher than the transmission speed of the wireless section, and the residence time of the data in the buffer 21 increases. There is a possibility that the buffer 21 overflows. Alternatively, when the transmission speed of the wired section is slower than the transmission speed of the wireless section, the data in the buffer 21 may be exhausted.

  Therefore, in the current wireless communication system, the requested rate information is transmitted to the wireless network device 12 from the wireless base station 11 every 100 ms, with the requested speed information being put in the control ATM cell of each channel.

Here, the maximum transmission rate of the control ATM cell 31 when the wireless transmission speed of the wireless terminal 13 is changed in units of 2 ms will be considered.
Assuming that the maximum number of channels CH is 192 and the wireless transmission rate fluctuation time Tc [ms] is 2 ms, the maximum transmission rate Rate of the control ATM cell can be expressed by the following equation.

Rate = (ATM cell [bit] × CH) / Tc = (53 × 8 [bit] × CH) / Tc
= (424 × 192) [bit] / 2 [ms] ≈40.7 [Mbps]
That is, in order to control the transmission rate for 192 channels in the wired section in units of 2 ms, a band of 40.7 Mbps is required for transmitting the control ATM cell. Therefore, the current control method cannot control the transmission speed of the wired section in units of 2 ms.

The invention disclosed in Patent Document 1 controls the transmission speed of the wired network by estimating the TCP segment retention amount of the wireless base station, and does not attempt to increase the communication speed control of the wired section. .
2005-244480 No. 2000-244521

  An object of the present invention is to make a change in communication speed in a wired section follow a change in communication speed in each channel in a wireless section of a wireless communication system.

  A communication method between a radio base station and a radio network control apparatus according to an embodiment of the present invention includes a radio terminal apparatus, a radio base station, and a radio network control apparatus, and the radio base station and the radio network control apparatus are wired to each other. A communication method in a wireless communication system connected with a wireless communication system, wherein required communication speed information of a plurality of communication channels of the wired line is multiplexed on a control ATM cell, and the wired line is transmitted from the wireless base station to the wireless network control device. And the communication speed of each communication channel of the wired line is controlled based on the requested communication speed information of each communication channel of the control ATM cell.

  According to this communication method, the number of control ATM cells transmitted from the wireless base station to the wireless network control device in order to control the communication speed of each communication channel of the wired line can be reduced. Thereby, since the transmission cycle of the control ATM cell can be shortened, the change in the communication speed of the wired line can be quickly followed by the change in the communication speed in the wireless section.

  In the communication method according to the above invention, each communication channel of the wired line is based on a reception environment of a radio signal of the wireless terminal device and data retention information of a storage unit that stores data to be transmitted to the plurality of wireless terminal devices. The requested communication speed is calculated.

  With this configuration, it is possible to appropriately control the communication speed of each communication channel of the wired line based on the change in the reception environment of the wireless terminal device and the change in the data retention information in the storage unit. Further, since the change in the communication speed of the wired line can be made to follow the change in the communication speed in the wireless section, data overflow and data depletion in the storage unit can be prevented. In addition, the margin of the storage capacity of the storage unit can be reduced.

  In the communication method, the required communication speed of each communication channel of the wired line is calculated based on data retention information in a storage unit that stores data to be transmitted to the plurality of wireless terminal devices.

  By configuring in this way, for example, the wireless base station can determine the required communication speed of the wired line by monitoring the retention amount or retention time of the data in the storage unit. Can be simplified.

  ADVANTAGE OF THE INVENTION According to this invention, the change of the communication speed of a wired line can be made to track rapidly the change of the communication speed of a radio area.

Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of a wireless communication system according to a first embodiment of this invention.
The wireless communication system of the embodiment described below is, for example, a high speed downlink packet access (HSDPA) wireless communication system, and adaptively uses a modulation method and an error correction coding method according to the wireless environment of the wireless terminal. Has been switched to. Further, the wireless transmission speed of each wireless terminal is changed in the range of 0 to 14 Mbps every 2 ms depending on the wireless environment and access state of the wireless terminal.

In the description of FIG. 1, the same blocks as those of the conventional wireless communication system of FIG.
The radio communication system according to the first embodiment includes a plurality of radio terminal devices 53, a radio base station (BTS: Base Transceiver Station) 51, and a radio network controller (RNC: Radio Network Controller) connected to a network 54. 52. The wireless base station 51 and the wireless network control device 52 are connected by a wired line, and communication on the wired line is performed using ATM cells.

  The radio base station 51 includes a buffer (storage unit) 21 that stores data (voice data, image data, etc.) of a plurality of communication channels (hereinafter referred to as channels), a coding unit 24, and a radio state determination unit 22. The scheduling unit 23, the flow control unit 61, and the control cell generation unit 62.

  The flow control unit (communication speed calculation unit) 61 performs scheduling such as radio state information (information indicating the radio environment of the radio terminal 53) obtained from the radio state determination unit 22 and a read rate of data output from the scheduling unit 23. Based on the information (indicating the communication speed of the wireless section) and the buffer information indicating the data retention state of the buffer 21, the required communication speed of the wired section in which the data retention time of the buffer 21 is a predetermined value or less is set. The requested communication speed information indicating the calculated communication speed (hereinafter referred to as request speed information) is output to the control cell generator 62 as a control signal.

  The control cell generation unit 62 multiplexes the request rate information of the plurality of channels output from the flow control unit 61 to assemble a control ATM cell and transmit it to the radio network control device 52. As a result, one virtual path for transmitting control information for controlling the communication speed of a plurality of channels of wired lines is set between the wireless base station 51 and the wireless network control device 52.

  The wireless network control device 52 includes a control cell receiving unit 63 that obtains control information of each channel from the control ATM cell, and a speed determination / assembly processing unit 64 that determines a requested rate of each channel and indicates a data transmission rate. And a data signal assembly processing unit 65 that assembles data received from the network 54 into an ATM cell and transmits the data to the radio base station 51 at a predetermined speed.

  The scheduling unit 23 of the radio base station 51, the flow control unit 61, the control cell generating unit 62, the control cell receiving unit 63 of the radio network control device 52, and the like are realized by software.

FIG. 2 is a block diagram of the main parts of the radio base station 51 and the radio network controller 52.
The flow controller 61 is provided for the number of channels, and outputs a control signal (requested speed information) of each channel to the control cell generator 62.

  The control cell generator 62 generates an ATM header, SC header, and control channel header of the control ATM cell, multiplexes the control signal and channel identification signal of each channel, and stores the multiplexed signal in the control ATM cell. 52. The control ATM generation unit 62 includes control information assembling processes for the number of channels for multiplexing the control information of each channel.

  The control cell receiving unit 63 of the wireless network control device 52 filters the control ATM cell received by the ATM header and the control channel header, and further filters the channel by the channel identification signal to obtain a control signal of a specific channel. . The control cell receiving unit 63 includes control signal acquisition processing for the number of channels to be filtered by the ATM header and channel identification signal of each channel.

  Based on the requested speed information of each channel output from the control cell receiver 63, the determination unit 64a of the speed determination / assembly processing unit 64 outputs the output interval and MAC (Media Access Control) -d layer PDU (Protocol Data Unit). The number is instructed to the output interval counter 64b and the output PDU number control unit 64c. The output interval counter 64b counts time and outputs an enable signal EN to the output PDU number control unit 64c every time the target value is reached. Each time the enable signal EN is output, the output PDU number control unit 64c assembles an ATM cell of the requested number of PDUs and transmits it to the radio base station 51.

  FIG. 3 is a diagram illustrating a format of the control ATM cell 68 according to the first embodiment. FIG. 3 shows the contents of the control ATM cell when transmitting control signals for 15 channels.

  The control ATM cell 68 is composed of a plurality of ATM cells. The header of the first control ATM cell 68 includes a 5-byte ATM header, a 3-byte SC (or CPS) header, and a 3-byte control channel. Contains the header. The payload stores control information for seven channels, each of which includes a 1-byte channel identification signal and a 5-byte control signal.

  Since the second control ATM cell 68 does not require a 3-byte control channel header indicating that it is a control ATM, control information for 7 channels (consisting of a channel identification signal and a control signal) is included in the payload. The control information for a total of 7.5 channels including the channel identification signal of the next channel and the control signal for 2 bytes is stored.

The third control ATM 68 stores the remaining 3 bytes of control information of the channel in which some data is stored in the previous control ATM cell.
Control ATM transmitted from the radio base station 51 to the radio network controller 52 by storing control information of a plurality of channels in an area that was not used in the conventional control ATM cell as described above. The number of cells can be greatly reduced.

  As shown in FIG. 4, the SC header includes a channel identifier CID (Channel Identifier), a payload length LI (Length Indicator), a UUI (User-to User Indication) indicating the presence / absence of divided transmission, and header error check information HEC. (Header Error Control).

  Next, processing contents on the radio base station 51 side of the first embodiment will be described with reference to the flowchart of FIG. The flowchart of FIG. 5 shows the processing contents of the flow control unit 61 and the control cell generation unit 62 of the radio base station 51.

  The flow control unit 61 of the radio base station 51 has acquired a transmission request signal for the requested rate information (control signal) of the radio section from the radio network control device 52, or the transmission cycle (for example, 2 ms cycle) of the control ATM cell. Is determined (FIG. 5, S11).

  When the transmission request signal of the requested rate information is acquired or when the transmission period of the control ATM cell is reached, the process proceeds to step S12 to create a channel control header that is identification information of the control ATM cell. In this first embodiment, as shown in FIG. 3, since the control channel header is 3-byte data, “3” is set in the counter count that counts the number of bytes of data multiplexed in the control ATM cell. To do.

  Next, channel information specifying a channel is collected (S13), and information indicating the radio state (wireless environment) of the radio terminal to which the channel is assigned is collected (S14). Further, the allocation frequency of data transmission allocated to each user at a cycle of 2 ms is collected (S15).

  Next, the maximum transmission rate of the radio section of the designated channel is calculated (S16). The maximum transmission rate of the wireless section is obtained by multiplying the average transmission rate of a specific user (wireless terminal) calculated from the wireless state by the allocation frequency.

  Next, buffer information is acquired (S17), and the dwell time (hereinafter referred to as buffer dwell time) of the transmission data buffer 21 is calculated (S18). The buffer residence time is calculated by dividing the average usage of the buffer 21 by the maximum transmission rate.

  Next, the required transmission rate (number of PDUs, output interval) of the wired section is calculated from the maximum transmission rate of the wireless section and the buffer retention time (retention information) of the corresponding communication channel (S19). The required transmission rate of the wired section is calculated by multiplying the maximum transmission rate of the wireless section by a coefficient determined by the buffer residence time. The reason why the coefficient determined by the buffer residence time is multiplied by the maximum transmission rate of the wireless section is to change the requested transmission rate of the wired section according to the buffer residence time. For example, when the buffer residence time is greater than or equal to a predetermined value, the maximum transmission rate is multiplied by a coefficient smaller than 1 to slow down the request transmission rate in the wired section and shorten the residence time of the buffer 21.

  The control cell generation unit 62 determines whether there is a difference between the requested transmission rate of the wired section of the corresponding channel at the previous control timing and the requested transmission rate of the wired section calculated by the flow control unit 61 this time. (S20).

  If there is a difference between the previous and current request transmission rates (S20, NO), the process proceeds to step S21, where a channel identification signal designating a specific channel is created and stored in the control ATM cell. For example, when the data length of the channel identification signal is 1 byte as shown in FIG. 3, "1" is set to the value of the counter count that counts the number of bytes of data stored in the control ATM cell in the process of step S21. to add.

  Next, the requested transmission rate (number of PDUs and output interval) of the wired section is stored in the control ATM cell (S22). For example, if the control signal is composed of 5-byte data as shown in FIG. 3, the value of the counter count for counting the data stored in the control ATM cell is set to “5” in the process of step S22. Is added.

  Next, it is determined whether or not the value of the counter count is “45” or more (S23). The processing in step S23 determines whether or not there is a vacancy in the remaining 45-byte area obtained by subtracting 5 bytes of the ATM header and 3 bytes of the SC header from the 53-byte ATM cell.

  When the value of the counter count is less than “45” (S23, NO), that is, when there is a new area for storing the channel identification signal and the requested speed information in the control ATM cell, the process proceeds to step S27, and all the setting targets are set. It is determined whether or not the processing for storing the requested speed information of the current channel has been completed.

When the request speed information storage process is not completed (S27, NO), the process returns to step S13, the channel information of the next channel is acquired, and the above-described process is repeated.
On the other hand, if it is determined in step S23 that the value of the counter count is “45” or more (S23, YES), that is, if there is no empty space in the 45-byte area of the control ATM cell, the process proceeds to step S24, where the ATM header Is stored in the control ATM cell. Further, an SC header is created and stored in the control ATM cell (S25). Further, the remainder when the value of the counter count is divided by “45” is set in the counter count. Thereafter, the process proceeds to step S27, and it is determined whether or not the setting of the requested speed information for the wired sections of all the channels to be set has been completed.

When the setting of all the channels to be set is completed (S27, YES), the process proceeds to step S28 and the created control ATM cell is transmitted.
6 (A) and 6 (B) are flowcharts showing processing contents on the radio network control device 52 side, and FIG. 6 (A) shows processing contents of the control cell receiving unit 63 and the speed determination / assembly processing unit 64. FIG. 6B shows the processing contents of the speed determination / assembly processing unit 64 and the data signal assembly processing unit 65.

  The control cell receiving unit 63 determines whether an ATM cell has been received (FIG. 6A, S31). When the ATM cell is received (S31, YES), the process proceeds to step S32, where the ATM cell and the control channel header are filtered to determine whether the ATM cell is a cell to be received. If the ATM cell is not a reception target cell, the process returns to step S31, and the ATM cell reception process is repeated.

  When it is determined that the ATM cell is a reception target (S32, YES), the process proceeds to step S33, and payload information is acquired. In the payload of the control ATM cell, a control signal (requested speed information) is stored in association with the channel identification signal as shown in FIG.

  Next, it is determined whether or not there is a cell having the same frame as the received control ATM cell (S34). If there is a control ATM cell of the same frame (S34, NO), the process returns to step S31 to receive the subsequent ATM cell.

  When there is no other cell in the same frame (S34, YES), the process proceeds to step S35, and a channel for obtaining the requested rate information from the control ATM cell is set (S35). Next, it is determined whether or not the same channel information (channel identification signal) as the set channel has been acquired (S36). If the same channel information as the set channel is acquired (S36, YES), the process proceeds to step S37, and the transmission rate of the request data (PDU number, output interval) stored in association with the channel identification signal is transmitted. Update the number of PDUs and the output interval of PDUs.

  Next, it is determined whether collection of requested speed information for the number of set channels has been completed (S38). If collection of requested speed information for the number of set channels has not been completed (S38, NO), the process returns to step S35 to obtain requested speed information for the next channel.

  If it is determined in step S38 that acquisition of requested speed information for the number of set channels has been completed (S38, YES), the process proceeds to step S39, and the update of the transmission rate of the wired section is terminated.

  If the speed determination / assembly processing unit 64 acquires the requested speed information of a specific channel (FIG. 6B, S41), it determines whether the value of the output interval counter 66 has reached the target value (S42). ). When the value of the output interval counter reaches the target value (S42, YES), the process proceeds to step S43 to instruct transmission of the number of PDUs based on the requested speed information. Then, the data signal assembly processing unit 65 assembles and transmits an ATM cell having the designated number of PDUs (S44).

Here, the maximum transmission rate when the requested rate information of a plurality of channels is multiplexed and transmitted in the control ATM cell in the first embodiment will be described.
When the period for changing the transmission rate of the wired section is Tc and the number of communication channels is CH, the maximum transmission rate Rate of the control ATM cell can be expressed by the following equation.

When the number of channels CH is 7 or less (CH ≦ 7)
Rate = ATM cell [bit] / Tc = 53 × 8 [bit] / Tc = 424/2 [ms]
= 0.212 [Mbps]
When the number of channels CH is larger than 7 (CH> 7)
Rate = (ATM cell [bit] / Tc) × (1 + roundup {(CH−7) /7.55}
Roundup is an operation for obtaining a value obtained by rounding up the number after the decimal point.

If the maximum number of channels CH is 192 channels and the period Tc is 2 ms, the maximum transmission rate Rate of the control ATM cell is given by the following equation.
Rate = (53 × 8 [bit] / Tc) × {1 + roundup {(192-7) /7.5}
= (424 [bit] / 2 [ms]) × {1 + roundup (24.66)
= (424 [bit] / 2 [ms]) × 26 = 5.512 [Mbps]
Therefore, according to the communication method of the first embodiment, the maximum transmission rate in the case where the required speed information of the wired section for 192 channels is transmitted to the wireless network control device 52 every 2 ms is 5.512 [Mbps]. It is possible to secure a sufficient communication band in the wired section that can be used for data transmission.

  According to the first embodiment described above, the control speed information transmitted from the radio base station 51 to the radio network controller 52 is multiplexed by transmitting the request speed information of the wired sections of a plurality of channels to the control ATM cell. The number of ATM cells can be reduced. As a result, the transmission speed of the wired section can be controlled at the same period as the period for controlling the transmission speed of the wireless section (for example, 2 ms), so that the change of the transmission speed of the wired section can be quickly changed to the change of the transmission speed of the wireless section. Can be followed. Note that the cycle for controlling the transmission speed of the wired section does not have to be the same as the cycle of changing the transmission speed of the wireless section when the dwell time of the buffer 21 can be ensured to be a predetermined time or less.

Next, FIG. 7 is a diagram illustrating a configuration of a wireless communication system according to the second embodiment, and FIG. 8 is a block diagram of main parts of the wireless base station 71 and the wireless network control device 72.
In the second embodiment, the flow control unit 81 of the radio base station 71 monitors the amount of data stored in the buffer 21, and the number of request PDUs in the wired section of each channel (request (Communication speed) is calculated, and the number of requested PDUs of a plurality of channels is multiplexed and transmitted in a control ATM cell.

  The wireless communication system according to the second embodiment includes a plurality of wireless terminals 53, a wireless base station 71, and a wireless network control device 72. In the following description, the same reference numerals are assigned to the same blocks as those in the conventional wireless communication system in FIG. 17 and their descriptions are omitted. The basic functions of the radio base station 71 and the network control device 72 are the same as those in the first embodiment shown in FIG.

  7 and 8, the flow control unit 81 of the radio base station 71 calculates the number of requested PDUs of the MAC-d layer of each channel based only on the buffer information indicating the average residence time of data in the buffer 21.

  The control cell generation unit 82 acquires the requested PDU number and channel identification signal of each channel output from the flow control unit 81, and uses the acquired request PDU number and channel identification signal of the MAC-d layer of each channel for control ATM. The cell is multiplexed, and further added with an ATM header, SC header, control channel header, etc., and transmitted to the radio network controller 72. This control ATM cell is transmitted at a minimum period of 2 ms, and one virtual path for transmitting the control ATM cell is set between the radio base station 71 and the radio network controller 72.

  The control cell receiving unit 83 of the radio network controller 72 filters the received ATM cell with the ATM header and the control channel header, and further filters with the channel identification signal to obtain the control signal (number of requested PDUs) of each channel. To do.

  The speed determination / assembly processor 84 controls the number of PDUs output from the data signal assembly processor 85 based on the number of requested PDUs of each channel output from the control cell receiver 83.

  FIG. 9 is a diagram illustrating a format of the control ATM cell 88 according to the second embodiment. FIG. 9 shows the contents of the control ATM cell 88 when transmitting control signals for 23 channels.

  The control ATM cell 88 is composed of a plurality of ATM cells, and a 5-byte ATM header, a 3-byte SC header, and a 3-byte control channel header are stored in the header of the first control ATM cell 88. ing. The payload stores control information for 21 channels, each of which includes a 1-byte channel identification signal and a 1-byte control signal.

  Since the second control ATM cell 88 does not require a 3-byte control channel header indicating that it is a control ATM, control information for 22 channels (consisting of a channel identification signal and a control signal) is included in the payload. Control information for 22.5 channels in total of 1-byte channel identification signals of the next channel is stored.

The payload of the third control ATM 88 stores a 1-byte control signal of a channel in which a part of data is stored in the previous control ATM cell.
By generating the control ATM cells in the format as described above, the number of control ATM cells transmitted from the radio base station 71 to the radio network control device 72 can be further reduced as compared with the first embodiment. As a result, the communication band of the wired section that can be used for data transmission can be made wider.

  Next, the processing content on the radio base station 71 side of the second embodiment will be described with reference to the flowchart of FIG. The flowchart of FIG. 10 shows the processing contents of the flow control unit 81 and the control cell generation unit 82 of the radio base station 71. In the following description, the same processes as those in the flowchart of FIG.

The processing in steps S11 to S13 in FIG. 10 is the same as the processing in the flowchart in FIG.
If the flow control unit 81 of the radio base station 71 acquires the buffer information indicating the average residence time of the data in the buffer 21 in step S14, the flow control unit 81 calculates the number of request PDUs in the wired section in the next step S51.

The control cell generation unit 82 determines whether or not there is a difference between the request PDU count of the previous wired section and the current request PDU count (S52).
If there is a difference between the previous and current request PDU numbers (S52, YES), the process proceeds to step S53, where a channel identification signal for a specific channel is created and stored in the control ATM cell. For example, when the data length of the channel identification signal is 1 byte as shown in FIG. 9, "1" is set to the value of the counter count that counts the number of bytes of data stored in the control ATM cell in the process of step S53. to add.

  Next, the calculated number of requested PDUs in the wired section of the specific channel is stored in the control ATM cell (S54). For example, when the number of requested PDUs is represented by 1-byte data as shown in FIG. 9, the value of the counter count that counts the data stored in the control ATM cell is “1” in the process of step S54. Is added.

  Next, it is determined whether or not the value of the counter count is “45” or more (S23). The processing in step S23 determines whether or not there is a vacancy in the remaining 45-byte area obtained by subtracting 5 bytes of the ATM header and 3 bytes of the SC header from the 53-byte ATM cell. The processing in steps S24 to S28 is the same as the processing in FIG.

  Next, FIGS. 11A and 11B are flowcharts showing processing contents on the radio network control device 72 side, and FIG. 11A shows processing of the control cell receiving unit 83 and the speed determination / assembly processing unit 84. FIG. 11B shows the processing contents of the speed determination / assembly processing unit 84 and the data signal assembly processing unit 85.

The processing in steps S31 to S36 in FIG. 11A is the same as the processing in steps S31 to S36 in FIG.
In step S36, the speed determination / assembly processing unit 84 determines whether or not the same channel identification signal as the set channel is acquired from the control ATM cell, and if the same channel identification signal is acquired (S36, YES), the process proceeds to step S56, the number of request PDUs stored in association with the channel identification signal in the control ATM cell is acquired, and the number of PDUs in the wired section of the corresponding channel is updated with the acquired number of request PDUs.

  Next, it is determined whether or not the collection of the required number of PDUs for the set number of channels has been completed (S57). If collection of the number of requested PDUs for the number of set channels has not been completed (S57, NO), the process returns to step S35 to acquire the number of requested PDUs for the next channel.

  If it is determined in step S57 that acquisition of the number of requested PDUs for the number of set channels has been completed (S57, YES), the process proceeds to step S58, and the update process for the number of requested PDUs in the wired section is completed.

  When the speed determination / assembly processing unit 84 acquires the number of requested PDUs for a specific channel in step S61 of FIG. 11B, in step S62, the speed determination / assembly processing unit 84 instructs transmission of the data signal with the number of requested PDUs. . The data signal assembly processing unit 85 assembles and transmits an ATM cell of the data signal with the instructed number of PDUs (S63).

  Here, in the second embodiment, a description will be given of the maximum transmission rate of the control ATM cell when the requested PDU number of a plurality of channels is transmitted on one or a plurality of control ATM cells.

When the period for changing the transmission rate of the wired section is Tc and the number of communication channels is CH, the maximum transmission rate Rate of the control ATM cell can be expressed by the following equation.
When the number of channels CH is 21 or less (CH ≦ 21)
Rate = ATM cell [bit] / Tc = 53 × 8 [bit] / Tc = 424/2 [ms]
= 0.212 [Mbps]
When the number of channels CH is greater than 21 (CH> 21)
Rate = (ATM cell [bit] / Tc) × (1 + roundup {(CH-21) /22.5}
If the number of channels CH is 192 channels and the period Tc is 2 ms, the maximum transmission rate Rate can be expressed by the following equation.

Rate = (53 × 8 [bit] / Tc) × {1 + roundup {(192-21) /22.5}
= (424 [bit] / 2 [ms]) × {1 + roundup (7.6)
= (424 [bit] / 2 [ms]) × 9 = 1.9 [Mbps]
Therefore, according to the communication method of the second embodiment, the maximum transmission rate when a control ATM cell multiplexed with the required speed information of the wired section for 192 channels is transmitted at a cycle of 2 ms is 1.9 [Mbps]. It is sufficient, and the communication bandwidth of the wired line that can be used for data transmission can be sufficiently secured.

  According to the second embodiment described above, the control ATM cell to be transmitted from the radio base station 51 to the radio network controller 52 is multiplexed by multiplexing the number of request PDUs in the wired section of a plurality of channels in the control ATM cell. The number of cells can be reduced. Thereby, the transmission speed of the wired section can be controlled at the same period as the period (for example, 2 ms) in which the transmission speed of the wireless section changes. Accordingly, it is possible to quickly follow the change in the transmission speed of the wired section to the change of the transmission speed of the wireless section. In addition, since the transmission speed of the wired section can quickly follow the change of the transmission speed of the wireless section, it is not necessary to increase the storage capacity margin of the buffer 21, and the size of the buffer 21 can be made smaller than before.

In the second embodiment, the flow controller 81 only needs to monitor the data retention time (or retention amount) of the buffer 21, so that the flow control is simplified.
In the second embodiment, only the data retention state of the buffer 21 is monitored, and the transmission rate between individual wireless terminals is not taken into consideration. Therefore, the cycle Tc for controlling the transmission rate in the wired section is It is desirable to set the cycle to be the same as or close to the cycle (for example, 2 ms) for changing the transmission rate of the wireless section.

  In the second embodiment described above, the maximum number of PDUs of control ATM cells transmitted at a period of 2 ms is 255, so the control signal is 1 byte, but a control signal of 2 bytes or more is transmitted. May be. Alternatively, when the maximum value of the number of PDUs is larger than 255, the accuracy of the data of the number of PDUs is reduced. For example, when “2” is transmitted as the number of PDUs, the radio network controller side multiplies “2”. The number of PDUs may be calculated, and data for the calculated number of PDUs may be transmitted. By doing so, the maximum value of the control signal can be increased without increasing the number of bits of the control signal.

  Next, FIG. 12 is a diagram showing the configuration of the wireless communication system according to the third embodiment of the present invention, and FIG. 13 is a block diagram of the main parts of the wireless base station 91 and the wireless network control device 92. In the third embodiment, the flow control unit 101 monitors only the retention information in the buffer 21, and stores the request speed information (number of requested PDUs) of the wired section of each channel in the order of the channel number in the control ATM cell. It is intended to be transmitted.

  The wireless communication system according to the third embodiment includes a plurality of wireless terminals 53, a wireless base station 91, and a wireless network control device 92. In the following description, the same reference numerals are assigned to the same blocks as those in the conventional wireless communication system in FIG. 17 and the description thereof is omitted. The basic functions of the radio base station 91 and the network control device 92 are the same as those of the first embodiment in FIG.

  12 and 13, the flow control unit 101 of the radio base station 91 acquires buffer information indicating the average residence time of data in the buffer 21, and generates a control cell using the number of request PDUs in the wired section of each channel as control information. To 102.

  The control cell generation unit 102 acquires the control information (number of requested PDUs) of each channel output from the flow control unit 101, and stores the acquired number of requested PDUs in the ATM control cell in the order of channel numbers.

  The control cell receiving unit 103 of the wireless network control device 92 filters the received ATM cell with the ATM header and the control channel header, and filters the control ATM cell storage location to control each channel (the number of requested PDUs). ) To get.

  The speed determination / assembly processing unit 104 controls the number of PDUs output from the data signal assembly processing unit 105 based on the number of requested PDUs of each channel output from the control cell receiving unit 103.

FIG. 14 is a diagram illustrating a format of the control ATM cell 108 according to the third embodiment.
The control ATM cell 108 is composed of a plurality of ATM cells, and a 5-byte ATM header, a 3-byte SC header, and a 3-byte control channel header are stored in the header of the first control ATM cell 108. ing. The payload stores control signals for 42 channels in order from the 1-byte control signal (number of requested PDUs) of the first channel.

  Since the second control ATM cell 108 does not require a 3-byte control channel header indicating that it is a control ATM, control signals for 45 channels are stored in the payload. Similarly, control signals for 45 channels are stored in the third, fourth,... Control ATM cells 108.

  By generating the control ATM cells 108 in the format as described above, the number of control ATM cells 108 transmitted from the radio base station 91 to the radio network controller 92 can be further reduced as compared with the second embodiment. . Thereby, it is possible to sufficiently secure the communication band of the wired section used for data transmission.

Next, processing contents on the radio base station 91 side and processing contents on the radio network control apparatus 92 side according to the third embodiment will be described with reference to the flowcharts of FIGS. 15 and 16.
The flowchart of FIG. 15 shows the processing contents of the flow control unit 101 and the control cell generation unit 102 of the radio base station 91. In the following description, the same processes as those in the flowchart of FIG.

The processing in steps S11 to S12 in FIG. 15 is the same as the corresponding step in the flowchart in FIG.
If the flow control unit 101 of the radio base station 91 collects channel identification information in step S13, in step S71, whether or not the channel is an unconfigured channel in which the transmission rate of the radio section has not been changed. Determine whether.

When the target channel is an unset channel (S71, YES), the process proceeds to step S72, and the process proceeds to step S72, where “0” is set as the number of request PDUs in the wired section.
On the other hand, when the target channel is not an unset channel (S71, NO), the process proceeds to step S74, and buffer information indicating the average residence time of data in the buffer 21 is acquired. In the next step S75, the number of requested PDUs in the wired section is calculated based on the data retention time in the buffer 21.

  After step S72 or S75, “0” or the calculated request PDU count is stored in the control ATM cell as the request PDU count of the corresponding channel. At this time, the number of request PDUs for each channel is stored in the order of channel numbers.

  The processing in steps S23 to S27 in FIG. 15 is the same as the processing in the corresponding steps in FIG. When the update of the number of requested PDUs of all channels is completed, a control ATM cell is transmitted in step S28.

Next, FIG. 16 shows processing contents of the control cell receiving unit 103 and the speed determination / assembly processing unit 104 of the wireless network control device 92.
The process of steps S31 to S34 in FIG. 16 is the same as the process of the corresponding step in FIG.

  When the speed determination / assembly processing unit 104 acquires the nth request PDU number of the control ATM cell in step S81, in the next step S82, the request PDU number of the corresponding channel is set to the request PDU number acquired this time. change.

In the next step S83, it is determined whether or not the requested PDU counts of all the channels of the control ATM cell have been collected.
If the request PDU counts of all channels have been collected (S83, YES), the process proceeds to step S84, and the control information update process is terminated.

Then, the speed determination / assembly processing unit 104 and the data signal assembly processing unit 105 execute the same processing as the processing in the flowchart of FIG.
The speed determination / assembly processor 104 instructs transmission of data signals with the required number of PDUs of the corresponding channel, and the data signal assembly processor 85 assembles and transmits ATM cells of the specified number of PDUs.

Here, in the third embodiment, a description will be given of a maximum transmission rate when a plurality of requested PDU numbers of channels are multiplexed and transmitted in a control ATM cell.
When the number of channels CH is 192 channels and the period for changing the transmission rate of the wired section is Tc, the maximum transmission rate Rate of the control ATM cell can be expressed by the following equation.

Rate = (ATM cell [bit] / Tc) × {1 + roundup {(CH−42) / 45}
= (53 × 8 [bit] / Tc) × {1 + roundup {(192-42) / 45}
= (424 [bit] / 2 [ms]) × {1 + roundup (3.33)
= (424 [bit] / 2 [ms]) × 5 = 1.06 [Mbps]
Therefore, according to the communication method of the third embodiment, the maximum transmission rate of the control ATM cell when transmitting the requested speed information (number of PDUs) of the wireless section for 192 channels every 2 ms is 1.06 [ Mbps], and the communication band of the wired section of the data signal can be made wider than in the second embodiment.

  According to the third embodiment described above, the radio base station 91 to the radio network controller 92 is configured by multiplexing the number of request PDUs for controlling the transmission speeds of the wired sections of a plurality of channels in the control ATM cell. The number of control ATM cells to be transmitted can be reduced. As a result, the transmission speed of the wired section can be controlled at the same period as the period for controlling the transmission speed of the wireless section (for example, 2 ms), so that the change of the transmission speed of the wired section can be quickly changed to the change of the transmission speed of the wireless section. Can be followed. In this way, by making the transmission speed of the wired section quickly follow the transmission speed of the wireless section, it is possible to prevent the data retention time of the buffer 21 from exceeding a predetermined value. Further, it is possible to prevent the data in the buffer 21 from being exhausted.

In the third embodiment, the flow control unit 101 only needs to monitor the data retention time in the buffer 21, so that the flow control is simplified.
This third embodiment is suitable for the case where the number of channels is relatively small because it is necessary to transmit the control ATM cell storing the requested rate information of all channels every cycle (for example, every 2 ms). . Depending on the number of channels, the communication direction of the second embodiment and the communication method of the third embodiment may be used properly.

  The configurations of the radio base station and the radio network control device are not limited to those shown in the embodiments, and may be other configurations. Further, the wireless communication system is not limited to the HSDPA method, and can be applied to other types of wireless communication.

(Supplementary note 1) A communication method in a wireless communication system comprising a wireless terminal device, a wireless base station, and a wireless network control device, wherein the wireless base station and the wireless network control device are connected by a wired line,
Requested communication speed information of a plurality of communication channels of the wired line is multiplexed on a control ATM cell and transmitted from the wireless base station to the wireless network control device via the wired line,
A communication method between a radio base station and a radio network controller, which controls the communication speed of each communication channel of the wired line based on the requested communication speed information of each communication channel of the control ATM cell.
(Additional remark 2) Based on the reception environment of the radio signal of the said radio | wireless terminal apparatus, and the staying information of the data of the memory | storage part which memorize | stores the data transmitted to several said radio | wireless terminal apparatus, the required communication speed of each communication channel of the said wired circuit A communication method between the radio base station and the radio network controller according to appendix 1, wherein
(Supplementary note 3) The wireless base station and the wireless unit according to supplementary note 1, wherein the required communication speed of each communication channel of the wired line is calculated based on data retention information in a storage unit that stores data to be transmitted to a plurality of the wireless terminal devices. A communication method with a network control device.
(Supplementary Note 4) Multiple control information including a set of channel identification information for identifying the communication channel and the requested communication rate information indicating the requested communication rate of the communication channel on the wired line is multiplexed in the control ATM cell. A communication method between the radio base station according to appendix 1 and the radio network control device,
(Supplementary note 5) The radio base station and radio according to supplementary note 1, wherein only the requested communication rate information indicating the requested communication rate on the wired line of the communication channel is multiplexed and transmitted to the control ATM cell in the order of the number of the communication channel. A communication method with a network control device.
(Supplementary note 6) The communication method between the radio base station and the radio network control device according to supplementary note 1, wherein channel identification information of the communication channel and the requested PDU number of the ATM cell are multiplexed and transmitted to the control ATM cell.
(Supplementary note 7) The communication method between the radio base station and the radio network control device according to supplementary note 1, wherein the radio communication system performs radio communication between the radio terminal device and the radio base station by an HSDPA method.
(Supplementary note 8) A wireless base station of a wireless communication system comprising a wireless terminal device, a wireless base station, and a wireless network control device, wherein the wireless base station and the wireless network control device are connected by a wired line,
A radio base station having a control cell transmission unit that multiplexes requested communication speed information of a plurality of communication channels in the wired line with a control ATM cell and transmits the information from the radio base station to the radio network control device via the wired line.
(Additional remark 9) It has a communication speed calculation part which calculates the required communication speed of a plurality of communication channels of the above-mentioned wired line,
9. The radio base station according to appendix 8, wherein the control cell transmission unit multiplexes and transmits the requested communication rate information of the plurality of communication channels of the wired line calculated by the communication rate calculation unit to the control ATM cell.
(Additional remark 10) Based on the reception environment of the radio signal of the said radio | wireless terminal apparatus, and the retention information of the data of the memory | storage part which memorize | stores the data transmitted to several said radio | wireless terminal apparatus, the required communication speed of each communication channel in the said wired line A communication speed calculation unit for calculating
9. The radio base station according to appendix 8, wherein the control cell transmission unit multiplexes and transmits the requested communication rate information of a plurality of communication channels calculated by the communication rate calculation unit to the control ATM cell.
(Additional remark 11) Additional remark 8 which has a communication speed calculation part which calculates the request | requirement communication speed of each communication channel of the said wired line based on the retention information of the data of the memory | storage part which memorize | stores the data transmitted to several said wireless terminal device. Wireless base station.
(Supplementary note 12) The control cell transmission unit includes a plurality of pieces of control information including a set of channel identification information for identifying the communication channel and the requested communication speed information indicating the requested communication speed on the wired line of the communication channel. 9. The radio base station according to appendix 8, wherein the radio base station multiplexes and transmits the control ATM cell.
(Supplementary note 13) A wireless network control device of a wireless communication system comprising a wireless terminal device, a wireless base station, and a wireless network control device, wherein the wireless base station and the wireless network control device are connected by a wired line,
A control ATM cell multiplexed with required communication speed information of a plurality of communication channels in the wired line is received via the wired line, and the required communication speed information of the plurality of communication channels is received from the received control ATM cell. A control cell receiver for extracting
A radio network control apparatus comprising: a cell transmission unit that controls a communication rate of an ATM cell for data to be transmitted to the radio base station based on the requested communication rate information of each communication channel extracted from the control ATM cell .
(Supplementary Note 14) A communication control program used for a wireless communication system including a wireless terminal device, a wireless base station, and a wireless network control device, wherein the wireless base station and the wireless network control device are connected by a wired line. ,
Processing for multiplexing required communication speed information of a plurality of communication channels in the wired line in a control ATM cell and transmitting the information from the wireless base station to the wireless network control device via the wired line;
A communication control program for causing a computer to execute processing for controlling the communication speed of each communication channel of the wired line based on the requested communication speed information of each communication channel of the control ATM cell.
(Additional remark 15) The process which calculates the required communication speed of the said wired circuit is based on the reception environment of the radio signal of the said radio | wireless terminal apparatus, and the retention information of the data of the memory | storage part which memorize | stores the data transmitted to the said several radio | wireless terminal apparatus. 15. The communication control program according to appendix 14, wherein the required communication speed of each communication channel of the wired line is calculated based on.

It is a figure which shows the structure of the radio | wireless communications system of 1st Embodiment. 1 is a block diagram of a radio base station and a radio network control device according to a first embodiment. FIG. It is a figure which shows the format of the ATM cell for control of 1st Embodiment. It is a figure which shows the structure of SC header. It is a flowchart which shows the process by the side of the wireless base station of 1st Embodiment. FIGS. 6A and 6B are flowcharts illustrating processing on the radio network control device side according to the first embodiment. It is a figure which shows the structure of the radio | wireless communications system of 2nd Embodiment. It is a block diagram of a radio base station and a radio network controller of the second embodiment. It is a figure which shows the format of the ATM cell for control of 2nd Embodiment. It is a flowchart which shows the process by the side of the wireless base station of 2nd Embodiment. 11, (A) and (B) are flowcharts showing processing on the radio network control apparatus side of the second embodiment. It is a figure which shows the structure of the radio | wireless communications system of 3rd Embodiment. It is a block diagram of a wireless base station and a wireless network control device of the third embodiment. It is a figure which shows the format of the ATM cell for control of 3rd Embodiment. It is a flowchart which shows the process by the side of the wireless base station of 3rd Embodiment. It is a flowchart which shows the process by the side of the radio | wireless network control apparatus of 3rd Embodiment. It is a figure which shows the structure of the conventional radio | wireless communications system. It is a figure which shows the format of the conventional ATM cell for control.

Explanation of symbols

51, 71, 91 Wireless base station 52, 72, 92 Wireless network controller 53 Wireless terminal 61, 81, 101 Flow controller 62, 82, 102 Control Cell generator 63, 83, 103 Control Cell receiver 64, 84, 104 Speed determination / assembly processing unit 65, 85, 105 Data signal assembly processing unit

Claims (5)

A communication method in a wireless communication system comprising a wireless terminal device, a wireless base station, and a wireless network control device, wherein the wireless base station and the wireless network control device are connected by a wired line,
Requested communication speed information of a plurality of communication channels of the wired line is multiplexed on a control ATM cell and transmitted from the wireless base station to the wireless network control device via the wired line,
A communication method between a radio base station and a radio network controller, which controls the communication speed of each communication channel of the wired line based on the requested communication speed information of each communication channel of the control ATM cell.   A request communication speed in the wired line of each communication channel is calculated based on a reception environment of a wireless signal of the wireless terminal device and data retention information of a storage unit that stores data to be transmitted to the plurality of wireless terminal devices. A communication method between the radio base station according to Item 1 and the radio network controller.   2. The radio base station and radio network control device according to claim 1, wherein the required communication speed of each communication channel of the wired line is calculated based on data retention information in a storage unit that stores data to be transmitted to a plurality of the radio terminal devices. How to communicate with. A wireless base station of a wireless communication system comprising a wireless terminal device, a wireless base station, and a wireless network control device, wherein the wireless base station and the wireless network control device are connected by a wired line,
A radio base station having a control cell transmission unit that multiplexes requested communication speed information of a plurality of communication channels in the wired line to a control ATM cell and transmits the information from the radio base station to the radio network controller via the wired line . A wireless network control device of a wireless communication system comprising a wireless terminal device, a wireless base station, and a wireless network control device, wherein the wireless base station and the wireless network control device are connected by a wired line,
A control ATM cell multiplexed with required communication speed information of a plurality of communication channels in the wired line is received via the wired line, and the required communication speed information of the plurality of communication channels is received from the received control ATM cell. A control cell receiver for extracting
A radio network control apparatus comprising: a cell transmission unit that controls a communication rate of an ATM cell for data to be transmitted to the radio base station based on the requested communication rate information of each communication channel extracted from the control ATM cell .

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