JP3645895B2 - Wireless transceiver, QoS control device, and transmission data QoS control method - Google Patents

Description

  The present invention relates to a radio transceiver, and more particularly to a QoS control method and a QoS control apparatus for transmission data in a radio transceiver.

  In recent years, with the spread of the Internet and low-cost IP communication networks, the use of IP in networks has been advanced. In an IP network, data is delivered from a source to a destination according to the IP protocol. IP is a network layer (third layer) protocol in the OSI reference model, and its upper layer includes TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) in the transport layer (fourth). TCP and UDP play a role of mediating between IP and application programs. As lower IP protocols, there are data link layer (second layer) and physical layer (first layer) protocols. For example, Ethernet (registered trademark) defined by IEEE802.3 and IEEE802.11. There is a wireless LAN.

  Wireless LAN technology is also applied to wireless access that implements a subscriber network wirelessly. In an IP network, various applications (for example, WEB access, IP phone, video conference, etc.) span wireless and wired systems. It is executable. There are applications that require real-time performance, such as video distribution and IP phone, and applications that do not require real-time performance, such as file data download.

  In an IP network, in order to deliver time-critical data such as voice and video to a destination device within a certain period of time, transmission data is classified for each traffic type in the network, and the QoS (Quality of traffic) at each node device. Priority (QoS) control for data transfer is applied in consideration of service of service. As a QoS control technique in an IP network, for example, MPLS and DiffServ at the network layer level and IEEE 802.1D at the data link layer level are known.

  The MPLS is described in, for example, “Multiple Protocol Label Switching Architecture” by E. Rosen et al., RFC3031, June 2001, P8-11 (Non-patent Document 1). Further, DiffServ is described in, for example, “An Architecture for Differentiated Service” by S. Blake et al., RFC 2475, December 1998, p10-18 (Non-patent Document 2).

  IEEE 802.1D is a QoS control technique in a wired LAN. For example, a priority display label is added to the header portion of an Ethernet frame, and each bridge device queues a transfer frame according to the priority. Realize control. In IEEE802.1D, for example, as shown in the priority classification of FIG. 13, traffic is “Network Control”, “Voice”, “Video”, “Controlled Load”, “Excellent Effort”, “Best Effort”, “Background”. ”And the priority 312 for each traffic is defined.

  Network Control is traffic necessary for maintaining the network environment, and is handled with the highest priority “7”. Voice and Video, which are limited in delay time and jitter, are handled with the next highest priority “6” and “5” after Network Control. Hereinafter, priorities are set in the order of Controlled Load, Excellent Effort, Best Effort, and Background, and normal LAN traffic such as mail and WEB access is associated with Best Effort.

  On the other hand, in wireless communication, an adaptive modulation scheme has been proposed in which communication is performed at a high speed if the condition of the wireless section is good, and communication is performed at a low speed when the wireless environment is deteriorated. For example, Toyoki Ue et al., “Symbol Rate and Modulation Level-Controlled Adaptive Modulation / TDMA / TDD System for High-Bit-Rate Wireless Data Transmission”, IEEE Transaction on Vehicular Technology, Vol. 47, November 1998. (Non-patent Document 3), JP-A-10-93650 (Patent Document 1), JP-A 2002-290246 (Patent Document 2), JP-A 2002-199033 (Patent Document 3). .

  In a communication system that employs an adaptive modulation scheme for wireless section communication, the information transmission rate varies depending on the state of the wireless section. Therefore, a QoS control technique is required that can maintain a necessary network environment even if the information transmission state in the wireless section changes.

Japanese Patent Laid-Open No. 10-93650

JP 2002-290246 A JP 2002-199033 A "Multiple Protocol Label Switching Architecture", RFC3031, June 2001, P8-11 "An Architecture for Differentiated Service", RFC2475, December 1998, p10-18 “Symbol Rate and Modulation Level-Controlled Adaptive Modulation / TDMA / TDD System for High-Bit-Rate Wireless Data Transmission”, IEEE Transaction on Vehicular Technology, Vol. 47, November 1998

  When the conventional QoS control used for the above-described wired LAN is applied to the wireless communication system adopting the adaptive modulation method in the wireless section, the transmission side radio device reads the label information added to the transmission data or the header, Processing for classifying each transmission data according to the label information occurs. In this case, since it takes time to classify transmission data, there is a problem that the delay time of data transmission increases and the throughput decreases.

  If the information transmission rate in the wireless section is larger than the transmission rate of transmission data supplied to the transmitting-side wireless device, no waiting time is generated in the transmission data in principle in the wireless device. However, since the conventional QoS control is configured to classify all transmission data on the assumption that transmission waiting time on the output line occurs, a high-speed processing circuit is required for the QoS control unit. There is a problem that the cost of the apparatus becomes high.

An object of the present invention is to provide a QoS control method and a control device for a wireless transceiver that can reduce the delay time of data transmission by QoS control and improve the data throughput.
Another object of the present invention is to provide a radio transceiver capable of shortening the delay time of data transmission by QoS control and improving the data throughput.
It is still another object of the present invention to provide an adaptive modulation type radio transceiver that employs QoS control to reduce data transmission delay time and improve data throughput.

  In order to achieve the above object, a QoS control device for a radio transceiver according to the present invention includes a QoS control unit that supplies transmission data to a modulation unit of a radio transceiver in an order that considers QoS, and an information transmission state of a radio section. And a determination unit connected to the QoS control unit that determines whether or not QoS control of transmission data is necessary, and the QoS control of the transmission data by the QoS control unit depends on the information transmission state in the radio section It is characterized by being selectively executed.

One of the features of the present invention is that the QoS control unit has a first operation mode in which transmission data is output in the order of input, and a second operation mode in which transmission data is output in an order that considers QoS, This is because the first and second operation modes can be switched according to the information transmission state.
According to another aspect of the present invention, the QoS control unit includes a comparison unit that compares the information transmission rate of the wireless section with a predetermined threshold, and when the information transmission rate of the wireless section is lower than the predetermined threshold, the QoS operation mode is set. This is because the mode is switched to the second operation mode, and when the information transmission rate in the wireless section becomes a predetermined threshold value or more, the mode is switched to the first operation mode.

Still another feature of the present invention is that the QoS control unit has a plurality of QoS control modes, and switches a QoS control mode to be applied to transmission data in accordance with an information transmission rate in a radio section.
According to still another aspect of the present invention, the QoS control unit includes a QoS control mode table that defines a relationship between a range of information transmission speed in a wireless section and a QoS control mode to be applied to transmission data, and the QoS control mode By referring to the table, the QoS control mode to be applied to the transmission data is determined according to the information transmission rate of the wireless section.

  According to still another aspect of the present invention, the QoS control unit includes a priority determination table (classification table) prepared in correspondence with a specific QoS control mode defined in the QoS control mode table. The classification table defines a class of transmission data corresponding to the value of specific header information included in each transmission data, and the QoS control unit refers to the classification table and performs the specific QoS control. The class of transmission data in the mode is determined.

  According to one embodiment of the present invention, when the information transmission rate in the wireless section is equal to or higher than a predetermined threshold, the QoS control process for the transmission data is omitted, so that data transmission with minimized transmission delay in the QoS control unit is possible. Thus, the data throughput can be improved. In addition, by omitting the QoS control process that requires high speed, the wireless transmitter can have a relatively inexpensive hardware configuration.

  According to one embodiment of the present invention, the QoS control for the transmission data is executed when the information transmission rate in the radio section falls below a predetermined threshold. In this case, since there is a time margin in supplying the transmission data to the wireless transmission circuit, the transmission delay due to the QoS control processing has little influence on the throughput. In addition, since the time margin increases as the information transmission rate in the wireless section decreases, the QoS control unit is provided with a plurality of QoS control modes, and the complex QoS control is applied as the transmission rate decreases. In addition, QoS control in which the QoS control mode is switched according to the information transmission state in the wireless section is also possible.

  According to the present invention, the necessity of QoS control is determined according to the information transmission state in the wireless section, and the QoS control is selectively executed. Therefore, compared with the conventional method in which the QoS control is always executed. Thus, the transmission delay time of transmission data can be shortened and the throughput can be improved. In addition, if a method of changing the QoS control mode to be applied according to the information transmission state in the wireless section using the QoS control mode table, data transmission flexibly corresponding to the wireless environment is possible.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing an embodiment of a radio transceiver according to the present invention.
The wireless transceiver includes a data input / output unit 10, a QoS control unit 11 that is a main part of the present invention, an access control unit 12 that receives transmission data subjected to QoS control from the QoS control unit 11, a modulation / demodulation unit 13, an RF Part 14, antenna part 15, internal bus 16 and control part 20. The modulation / demodulation unit 13 employs an adaptive modulation system that makes the data transmission rate variable depending on the situation of the radio section.

  The QoS control unit 11 performs selective QoS control on the transmission data supplied from the data input / output unit 10 according to the information transmission rate of the wireless section input from the modulation / demodulation unit 13 via the signal line L13. Then, the transmission data is output to the access control unit 12 via the signal line L11. The transmission data is output from the access control unit 12 to the modem unit 13, modulated by the modem unit 13, converted to a radio frequency by the RF unit 14, and transmitted from the antenna unit 15 to the radio section.

  On the other hand, the radio signal received from the antenna unit 15 is frequency-converted by the RF unit 14, demodulated by the modem unit 13, and input to the access control unit 12 as received data. The reception data is transferred from the access control unit 12 to the data input / output unit 10 via the internal bus 16 and output as reception information.

  The control unit 20 controls the entire wireless transceiver. Here, the control unit 20, the QoS control unit 11, and the access control unit 12 are shown as individual elements. However, the QoS control unit 11 and the access control unit 12 are integrated, and the functions of the control units are combined on one processor. It may be realized by software executed on the control unit 20 or may be realized by software executed on the control unit (processor) 20.

  For example, the access control unit 12 may be configured to generate transmission data in a format defined by §17.3.2 PLCP Frame Format of IEEE Standard 802.11a. In the PLCP frame format, for example, as shown in FIG. 15, the transmission rate (modulation method) of the data field is defined by the rate bit set in the signal field. The signal field is transmitted at a fixed rate.

FIG. 2 shows a detailed view of the QoS control unit 11.
The QoS control unit 11 includes a buffer memory 111 for temporarily holding transmission data supplied from the data input / output unit 10, a priority determination processing unit (classification processing unit) 110, and a transmission queue 112 for each class. The transmission buffer memory 112 in which −0 to 112-n is formed, and the transmission data are read from the transmission buffer memory 112 in the order set in advance considering the QoS, and output to the access control unit 12 via the signal line L11. A read control unit 113, a classification processing unit 110, and a QoS control information table memory 30 referred to by the read control unit 113.

FIG. 3 is a flowchart showing the operation of the classification processing unit 110 (classification processing 1110).
The classification processing unit 110 determines whether or not transmission data has arrived at the buffer memory 111 (step 1111). When the transmission data arrives, the wireless section input from the modem unit 13 via the signal line L13 The information transmission speed x is checked (1112). When the wireless section information transmission rate x is equal to or higher than the predetermined threshold A, the QoS control process is omitted and the transmission data is stored (queued) in the default transmission queue 112-0 (1115). Here, the threshold A indicates, for example, the maximum transmission rate of transmission data input from the data input / output unit 10, and the transmission speed x ≧ threshold A indicates that the transmission data in the transmission buffer 112 is congested (waiting time). It means a state that does not occur.

  In the present invention, QoS control is executed only when the wireless section information transmission rate x is smaller than the threshold A, that is, when congestion occurs in transmission data. In this case, the classification processing unit 110 determines the transmission data class p by referring to the QoS control information table memory 30 (1113), and stores the transmission data in the transmission queue 112-p corresponding to the class p (1114). ). When one transmission data is stored in the transmission queue 112-0 or 112-p, the process returns to step 1111 and the same operation is repeated for the next transmission data.

  In this embodiment, QoS control is executed independently of the counterpart station. In this case, the information transmission rate X in the radio section is derived from, for example, the modulation scheme selected by the propagation path estimation means (propagation path estimation unit 11-1 shown in FIG. 16) omitted in FIG. When the modulation method is estimated, the information transmission rate X can be obtained from a reception level-modulation method correspondence table shown in FIG. However, QoS control may be performed according to the partner station. In this case, for example, the information transmission rate and the modulation method to be adopted by the own station may be determined from the information transmission rate X included in the received data.

FIG. 4 is a flowchart showing the operation of the read control unit 113 (read control process 1130).
The read control unit 113 determines whether or not data transmission is possible from the state of the enable signal output from the access control unit 12 to the signal line L12 (step 1131). Transmission data is sequentially read from the transmission queue of high priority in the transmission buffer memory 112, and output to the access control unit 12 via the signal line L11 (1132).

  As a method for reading transmission data in a band guaranteed for each class, for example, a token bucket method is known. In this method, a token corresponding to the bandwidth is given to each transmission queue, and data transmission is enabled during the token existence period. The token is replenished according to the guaranteed bandwidth at regular time intervals and consumed according to the data transmission amount. The read control unit 113 refers to the class-specific bandwidth allocation memory area of the QoS control information table memory 30 at regular intervals, and performs the above-described token supply and token consumption associated with data reading.

  In the present invention, the classification process executed in step 1113 of FIG. 3 can be performed in accordance with the method defined in the IEEE 802.1D described above, for example. The classification processing unit 110 reads the transmission data or the priority display label included in the header part, determines the priority p of each transmission data, and sends the transmission data to the transmission queue 112-p of the class corresponding to the priority. Queue. However, since this method is based on the premise that priority display labels are added to all transmission data, QoS control cannot be executed unless priority display labels are added to the transmission data. .

  Therefore, in one embodiment of the present invention, a priority display label is added to transmission data using a classification table in which classes are defined corresponding to values of specific header information extracted from the header portion of transmission data. Even if not, the class of each transmission data can be determined. Hereinafter, an embodiment in which a class is determined from a port number included as header information will be described.

FIG. 5 shows a case where the wireless client 20B refers to a Web page on the server 20A using a Web browser as an example of communication to which the wireless transceiver of the present invention is applied.
For example, an IP address “172.20.100.34” is assigned to the wireless client terminal 20B, and TCP and UDP are used as the transport layer 23B, TCP and UDP as the application layer 24B, and a Web browser and Telnet as the application layer 24B. SNMP (Simple Network Management Protocol) is installed above UDP. Here, TCP and UDP are identified by protocol numbers “6” and “17”, respectively, and Telnet and SNMP are identified by port numbers “23” and “161”. The Web browser is specified by a port number arbitrarily given on the client side, here “2001”.

  On the other hand, in this example, the server 20A has an IP address “172.20.100.32”, is equipped with TCP and UDP as the transport layer 23A above the IP protocol 22A, and is HTTP above the TCP as the application layer 24A. And Telnet, UDP is installed above UDP. HTTP is identified by a port number “80”.

When referring to the Web page, the Web browser of the client 20B communicates with the HTTP of the server 20A. At this time, the IP packet 400 transmitted from the client 20B to the server 20A has, for example, the header content shown in FIG.
The IP packet 400 includes a data part 40, a TCP header 41, and an IP header 43. The TCP header 41 includes a transmission source port number 411 indicating a Web browser and a destination port number 412 indicating HTTP. The IP header 43 includes a transmission source IP address 431 indicating the client 20B, a destination IP address 432 indicating the server 20A, and a protocol number 433 indicating that the applied protocol of the transport layer header 41 following the IP header is TCP. Is included.

7 shows the detailed format of the IP header 43, and FIG. 8 shows the detailed format of the TCP header 41.
The TCP header 41 includes a sequence number and other multi-item header information in addition to the transmission source port number 411 and the destination port number 412 described above. When the protocol number 433 of the IP header is “17”, the UDP header 42 shown in FIG. 9 is adopted instead of the TCP header. The UDP header 42 also includes a transmission source port number 421 and a destination port number 422 for identifying an application, and has a simpler header format than the TCP header.

  In this embodiment, in order to associate the port number extracted from the TCP (or UDP) header of the transmission packet with the class, for example, the classification table 32 corresponding to the port number shown in FIG. prepare. In the classification table 32, the value of the class 322 is defined in correspondence with the value of the port number 321 that can be applied to the TCP header or the UDP header.

  In the class determination step 1113, the classification processing unit 110 extracts the protocol number 433 from the IP header of the transmission data (transmission packet), determines the application protocol from the protocol number, and determines the transport layer header according to the application protocol. Recognizing the structure, the value of the source port number 411 (or 421) is read. Next, the port number corresponding classification table 32 shown in FIG. 10 is searched for an entry where the port number 321 matches the value of the transmission source port number of the transmission data, and the value p of the class 322 indicated by the entry The transmission data is queued in the corresponding transmission queue 112-p (1114). When the value of the transmission source port number 411 (or 421) is not registered in the classification table 32, the transmission data is queued in the default transmission queue. For example, the read control unit 113 implements predetermined QoS by reading data from the queue for each class according to the class-specific bandwidth allocation table 35 shown in FIG.

  According to the above embodiment, in a state where the data transmission rate in the modem unit 13 is equal to or higher than a predetermined threshold, that is, in a state where congestion does not occur in the transmission buffer 112, a quick data transmission without the QoS control process is performed, When the transmission rate falls below a predetermined threshold, data transmission adapted to the information transmission rate fluctuation in the wireless section is performed by selectively transmitting transmission data by QoS control corresponding to the port number (type of transmission source application). Is possible.

  In a wireless communication system, even if the information transmission rate in a wireless section decreases, for example, the minimum necessary network control such as Network Control defined by IEEE 802.1D, or between specified terminals (specific connections) specified in advance. As for communication, there is a case where it is desired to ensure communication quality. In such a case, according to the present invention, various QoS controls can be performed by preparing a plurality of types of tables in the QoS control information table memory 30 as described below.

FIG. 11 shows a QoS control mode table 33 that is referred to in order to switch the QoS control mode to be executed in accordance with the information transmission rate in the radio section.
The QoS control mode table 33 includes a QoS control mode 331 and an enable bit flag column 332 for designating a QoS control mode to be applied according to the information transmission rate of the wireless section. In this example, the enable bit flag field 332 indicates the range of the information transmission rate x in the wireless section as “x <lower threshold B”, “lower threshold B ≦ x <upper threshold A”, and “upper threshold A ≦ x”. The QoS control mode that can be applied is specified by the flag of the enable bit in each speed range.

  In the QoS control mode “802.1D”, the class is determined according to the priority display label of IEEE 802.1D. In the QoS control mode “port number”, a class is determined by the classification table 32 shown in FIG. In addition, the QoS control mode “control policy A”, for example, determines a class using a MAC address correspondence classification table 34 that specifies a class 342 corresponding to the value of the MAC address 341 as shown in FIG. To do.

  In the QoS control mode table 33 exemplified here, when “upper limit threshold A ≦ x”, the enable bit is set to the disabled state (“0”) in all QoS control modes. Therefore, when the information transmission rate x in the wireless section is equal to or higher than the upper limit threshold A, QoS control is omitted and all transmission data is queued in the default transmission queue.

  When the information transmission rate x in the wireless section is lower than the upper threshold A and equal to or higher than the lower threshold B, the QoS control mode “802.1D” and the QoS control mode “port number” are applied. Therefore, for transmission data to which 802.1D label information is added, the label information is determined to determine the class, and for transmission data having no 802.1D label information, the class is determined from the classification table 32. QoS control is executed in the following format.

  In this example, when the information transmission rate in the wireless section is lower than the lower threshold B, the QoS control mode “802.1D” and the QoS control mode “control policy A” are applied. Therefore, for transmission data to which 802.1D label information is added, the label information is determined to determine the class, and for transmission data having no 802.1D label information, the classification table 34 of the control policy A is used. QoS control is executed in the form of determining a class from

  For example, when transmitting a transmission packet in the Ethernet frame format, each transmission data has an Ethernet MAC header including the source and destination MAC addresses added before the IP header. Therefore, the classification processing unit 110 analyzes the MAC header for transmission data that does not have 802.1D label information, and the address 341 is the transmission source MAC address of the transmission data from the classification table 34 of the control policy A. Search for entries that match. When the target entry is found, the transmission data is queued in the transmission queue 112-p corresponding to the value p indicated by the class 342 of the entry. When the target entry is not found, the transmission data is queued in the default transmission queue. Queue.

  For class determination, header information other than the transmission source port number and MAC address shown in the embodiment, for example, destination port number, protocol type such as UDP, TCP, etc. may be used. Also, by specifying the MAC address and the port number, it is possible to specify the class for the specific terminal, the specific application, and the specific application. Furthermore, for example, a terminal may be identified by an address other than the MAC address, such as a source / destination IP address, and the priority of data for communication between specific terminals may be determined. In any of the above cases, a classification table indicating the correspondence between the header item to be determined and the class, and a class-specific bandwidth allocation table are prepared in the memory 30, and the QoS control mode to be applied and information transmission of the wireless section are applied. The relationship with the speed may be specified in the QoS control mode table 33. The class-specific bandwidth allocation table 35 may be provided for each corresponding QoS control mode allocation, or a different table may be used for each information transmission rate in the wireless section.

  For example, when the QoS control information table memory 30 is configured by a nonvolatile memory such as NVRAM, the various tables 31 to 35 described above are written in the memory 30 in advance when the wireless transceiver is shipped. Further, if necessary, for example, in the form of transmitting a control message included from a device such as a maintenance PC, update data is given to the corresponding wireless transceiver, and memory is stored in the control unit 20 by maintenance software prepared in advance. The update data is written in 30.

  When the memory 30 is composed of a volatile memory such as a RAM, for example, the contents of the master table are written in the ROM or nonvolatile memory included in the control unit 20, and the power of the wireless transceiver is turned on. Sometimes, the contents of the master table may be automatically copied to the memory 30. When the power is turned on, the wireless transceiver automatically communicates with the maintenance PC, and the control unit 20 may write the table contents downloaded from the maintenance PC into the memory 30. According to the latter method, even when the QoS control mode to be applied or the table contents are changed, it is possible to quickly change the function of each wireless transceiver.

Next, another embodiment of the radio transceiver according to the present invention will be described with reference to FIG.
The present embodiment is characterized in that the above-described QoS control is applied to a wireless transceiver of an adaptive modulation transmission system. The wireless transmitter / receiver of the adaptive modulation transmission method receives the signal based on the received power, the bit error rate detected when demodulating the wireless signal with the error correction code transmitted by the transmission side using an arbitrary modulation method, and other information. For example, 64QAM (64-positions Quadrature Amplitude Modulation), 16QAM (16-positions Quadrature Amplitude Modulation), QPSK (Quadrature Phase Shift Keying), BPSK (Binary (Phase Shift Keying) and an appropriate modulation method are selected from the other modulation methods, and reception processing is performed according to the modulation method.

  As shown in FIG. 16, the wireless transceiver of this embodiment includes a QoS control unit 11-2, a radio frame encoding unit 12-1, a modulation unit 13-1, a transmission RF unit 14-1, a duplexer 14, and an antenna. 15, a reception RF unit 14-2, a demodulation unit 13-2, a radio frame decoding unit 12-2, and a propagation path estimation unit 11-1.

  The transmission data is subjected to QoS control by the QoS control unit 11-2, and is input to the radio frame coding unit 12-1 after changing the transmission order. The radio frame encoding unit 12-1 divides transmission data into frame units, performs error correction encoding processing, and then adds a training bit and a guard bit to generate a radio section transmission frame. The radio section transmission frame is input to the modulation unit 13-1, modulated by a predetermined modulation method, converted to a radio frequency by the transmission RF unit 14-1, and wireless space via the duplexer 14 and the antenna unit 15. Is sent out.

  On the other hand, the radio signal received by the antenna unit 15 is input to the reception RF unit 14-2 via the duplexer 14 and converted into a baseband signal. The baseband signal is input to the demodulation unit 13-2, demodulated by a predetermined demodulation method corresponding to the modulation method on the transmission side, and then input to the radio frame decoding unit 12-2. Radio frame decoding section 12-2 performs error correction decoding processing on the received demodulated data and outputs it as received data. The propagation path estimation unit 11-1 estimates the state of the propagation path from the output signal of the demodulation unit 13-2, selects an optimal modulation scheme, and sends it to the radio frame encoding unit 12-1 and the modulation unit 13-1. On the other hand, the modulation method to be applied is designated.

  FIG. 17 shows a configuration example of an FWA (Fixed Wireless Access) system to which the wireless transceiver of the present embodiment is applied. The FWA system is composed of a base station and a plurality of terminal stations, and realizes data communication between stations by connecting the base station and each terminal station in a point-to-point (PP) format.

FIG. 18 is a sequence diagram illustrating a connection procedure between a base station and an end-to-end station that are P-P connected.
When the power is turned on, the base station starts transmission of synchronization codes and acquisition of reception synchronization. On the other hand, the terminal station starts acquisition of reception synchronization and starts transmission of a synchronization code when reception synchronization is established. When the base station captures the synchronization code from the terminal station and establishes reception synchronization, the base station starts data transmission in a predetermined data transmission frame format. The terminal station executes reception processing of the data transmission frame from the base station and starts its own data transmission in a predetermined data transmission frame format. The synchronization frame and the data transmission frame are modulated by a modulation scheme determined in advance between the base station and the terminal station. As described above, in the FWA system, after establishing synchronization between the base station and the terminal station, data is transmitted and received by a modulation scheme designated in advance.

  Here, an operation of adaptive modulation for switching the modulation scheme according to the state of the propagation path after starting data communication will be described. The propagation path estimation parameters generally include a reception level, an equalization error, and a bit error rate. For example, Patent Document 1 and Non-Patent Document 3 describe propagation path condition estimation. In the present embodiment, a case where the propagation path estimation unit 11-1 estimates the state of the propagation path from the reception level of the radio signal will be described.

  The propagation path estimation unit 11-1 periodically receives the reception level information of the reception signal from the demodulation unit 13-2, and selects an optimal modulation method with reference to the reception level-modulation method correspondence table shown in FIG. . The selected modulation method is notified to the QoS control unit 11-2, the radio frame encoding unit 12-1, and the modulation unit 13-1 by the modulation method identification code indicated in the table.

  The radio frame encoding unit 12-1 generates a data transmission frame with the modulation scheme identification code notified from the propagation path estimation unit 11-1 added thereto. The modulation unit 13-1 determines whether or not the modulation scheme identification code is updated for each frame, and when the modulation scheme identification code is different from the identification code of the currently applied modulation scheme, switches the modulation scheme from the next frame. .

  A similar modulation scheme identification code is also added to the received frame from the base station. Radio frame decoding section 12-2 extracts a modulation scheme identification code from the data frame after error correction decoding, and notifies demodulation section 13-2. The demodulation unit 13-2 stores the modulation scheme identification code notified from the radio frame decoding unit 12-2. When the modulation scheme identification code is changed, the demodulation unit 13-2 switches the demodulation scheme from the next frame to a new one. The received frame is demodulated by the demodulation method. Similarly, on the base station side, when the modulation scheme identification code added to the received frame from the terminal station is changed, the demodulation scheme is switched from the next frame.

  An example of the format of the data transmission frame is shown in FIG. The frame for data transmission includes a training bit TRN for timing synchronization, an RCB (Radio Control Block) in which a modulation system identification code (MODTYPE) and maintenance information are set, as shown in FIG. As shown in (C), a plurality of DTBs (Data Transfer Blocks) in which data traffic (transmission data) is set and guard bits G indicating a delimiter between frames are included.

The radio frame encoding unit 12-1 uses the MODTYPE field prepared in the RCB of each transmission frame to transmit the modulation scheme identification code notified from the propagation path estimation unit 11-1 to the partner station (in this example, the base station). Bureau). The RCB does not need to be transmitted every frame, and may be transmitted, for example, every several frames or whenever the modulation method is changed. In this case, in a frame in which RCB is omitted, DTB can be transmitted instead of RCB. As a synchronization code at the time of capturing the synchronization, for example, a bit string scrambled with 0 may be used.
In the propagation path estimation unit 11-1, in order to suppress frequent switching of the modulation method due to the variation of the reception level, an optimum modulation method is selected from the average value of the reception level in a predetermined period as necessary. Also good. Further, the error correction state in the radio frame decoding unit 12-2 may be reflected in the propagation path state estimation.

  In the present embodiment, application to a wireless system in which a base station and a terminal station are connected by P-P has been described. However, in the present invention, a base station and a terminal station are connected by P-MP (Point to Multi Point). It can also be applied to other wireless systems.

  In the present embodiment, it is desirable that the radio base station be installed at a position that can be seen from each terminal station. However, when a new base station is arranged, the influence on the existing base station that is already in operation is avoided as much as possible. Therefore, the installation position needs to be examined sufficiently in advance. However, even if the position is determined to be optimal in the prior examination, there may be a case where a new base station having an effect is found when actually placed. In such a case, for example, an active system and a standby system are prepared in advance as base stations (or subscriber stations), and the radio communication environment is optimized by switching the system according to a control command from the management center of the network. You just have to do it. Note that a wireless system including active and standby wireless transceivers is disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-94449.

  As described above, the embodiment of the present invention has been described by taking the packet transmission to which the TCP / IP protocol is applied as an example. However, the idea of the present invention is not limited to the specific communication protocol shown in the embodiment, and other protocols are used. It can also be applied to. In the embodiment, the token bucket method is adopted. However, in the present invention, as the data read control method, another control method capable of reading the transmission data in order from the queue with the higher priority may be applied. .

The block diagram which shows one Example of the radio | wireless transmitter / receiver by this invention. The figure which shows the detail of the QoS control part 11 shown in FIG. 3 is a flowchart showing the operation of the classification processing unit 110 shown in FIG. 3 is a flowchart showing the operation of the read control unit 113 shown in FIG. The figure which shows one example of the communication to which the radio | wireless transmitter / receiver of this invention is applied. The figure which shows an example of the header content of the IP packet communicated between the client 10B and the server 10A of FIG. The figure which shows the detailed format of the IP header 43. FIG. The figure which shows the detailed format of the TCP header 41. FIG. The figure which shows the detailed format of the UDP header 42. The figure which shows an example of the classification table 32 corresponding to a port number. The figure which shows one example of the QoS control mode table. The figure which shows an example of the classification table 34 of the control policy A. The figure for demonstrating the priority division in IEEE802.1D. The figure which shows one example of the bandwidth allocation table 35 classified by class. The figure which shows the frame format of IEEE802.11a. The block diagram which shows an example of the radio | wireless transmitter / receiver of the adaptive modulation system to which the QoS control of this invention is applied. The block diagram of the FWA system to which the QoS control of this invention is applied. The sequence diagram which shows one example of the connection procedure between the base station of a point-to-point connection, and a terminal station. FIG. 17 is a diagram illustrating an example of a reception level-modulation method correspondence table referred to by the propagation path estimation unit 11-1 in FIG. The figure which shows an example of the format of the frame for data transmission.

Explanation of symbols

10: Data input / output unit, 11: QoS control unit 11, 12: Access control unit, 13: Modulation / demodulation unit, 14: RF unit, 15: Antenna unit, 16: Internal bus, 20: Control unit,
30: Memory for QoS control information table,
31: IEEE 802.1D priority determination table,
32: Classification table corresponding to port number,
33: QoS control mode table,
34: Priority determination table corresponding to MAC address,
35: Control policy A classification table 110: Classification processing unit
111: Buffer memory, 112: Transmission buffer memory,
112-0 to 112-n: class-specific transmission queue, 113: read control unit.

Claims (3)

A QoS (Quality of Service) control device used for a wireless transceiver, which is configured to control transmission of transmission data to a modulation unit of the wireless transceiver in an order considering QoS, and according to the information transmission state of the wireless section A determination unit connected to the QoS control unit for determining whether or not QoS control of transmission data is necessary,
A QoS control apparatus, wherein QoS control of transmission data by the QoS control unit is selectively executed according to an information transmission state in a radio section. A QoS (Quality of Service) control method in a wireless transceiver,
A first step of determining whether or not QoS control of transmission data is necessary according to an information transmission state of a wireless section;
If it is determined that QoS control is necessary, a second step of supplying transmission data to the modulation unit of the wireless transceiver in an order that takes QoS into account;
A QoS control method comprising: a third step of supplying transmission data to the modulation unit in the input order when it is determined that QoS control is not necessary. A wireless transceiver including a receiving unit and an adaptive modulation type transmission unit connected to an antenna, wherein the adaptive modulation type transmission unit is
A high-frequency unit connected to the antenna;
A modulation unit connected to the high-frequency unit;
A radio frame encoding unit that is connected to the modulation unit and converts transmission data into a format of a modulation scheme according to a situation of a propagation path in a radio section;
A QoS control unit for supplying transmission data to the radio frame encoding unit in an order considering QoS (Quality of Service);
A wireless transceiver having a QoS control unit for outputting transmission data in order of priority.

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