CN1925481B - Wireless Local Area Network Device and Its Frame Sequence Numbering Method - Google Patents

Abstract

A frame serial number numbering method is used for serial numbering the data units used by the wireless local area network, which includes the following steps: receiving data units and their receiving workstation addresses and transmission rates (TXRate); and different receiving workstation addresses and different The data units of the transmission rate are serial numbered separately. The present invention also provides a wireless local area network device. When the wireless local area network device uses the method of the present invention to transmit data, its corresponding receiving device can use the method of the present invention to calculate the frame error rate of the wireless local area network device at different transmission rates.

Description

Wireless Local Area Network Device and Its Frame Sequence Numbering Method

【Technical field】

The present invention relates to a wireless local area network, in particular to a wireless local area network device and its frame serial number numbering method.

【Background technique】

The Institute of Electrical and Electronics Engineers (IEEE) standard-802.11 defines the main structure of the Media Access Control (MAC) frame format, which includes three types: data frame, management frame and control frame. As shown in FIG. 1 and FIG. 2 , they are a MAC data frame 100 and a MAC management frame 200 respectively. Each of the data frame 100 and the management frame 200 includes a sequence control field 160 , 260 . The sequence control fields 160 and 260 respectively include two subfields: a segment number (SegmentNumber) field 161 and 261 and a sequence number (Sequence Number, hereinafter referred to as SN) field 162 and 262. Wherein, the sequence number is the sequence number of the MAC Service Data Unit (MAC Service Data Unit, hereinafter referred to as MSDU) or MAC Management Protocol Data Unit (MAC Management Protocol Data Unit, hereinafter referred to as MMPDU) carried by the frame. Each MSDU or MMPDU has a sequence number whose value starts from 0 to 4095.

In the traditional method, no matter MSDU or MMPDU, the serial number of the data unit transmitted by the transmitting device is always accumulated, and the sequence number is accumulated to 4095 and then starts from the beginning. But generally speaking, transmission devices have different transmission rates for the three different frames of IEEE 802.11. Management frames and control frames are usually transmitted at the basic rate, while data frames are usually transmitted at the highest supported transmission rate.

In addition, the general transmitting device will use whether the receiving device responds to the Acknowledgment signal (ACK signal) as the calculation basis for its frame error rate, and some devices use this as the basis for whether the transmission rate is slowed down. But in the following cases, the frame error rate cannot be obtained by the receiving end.

The first situation is that the broadcast frame or some management frames do not require the receiving device to respond to the ACK signal, so the transmitting device cannot know whether the transmitted frame reaches the receiving device successfully.

The second case is: No-ACK (no-acknowledgment) collision problem, a frame transmitted by a device supporting no-ACK does not require the receiving device to respond with an ACK.

Under the above circumstances, the transmitting device cannot calculate its frame error rate according to whether the receiving device responds to the ACK signal, and even in the same environment, other receiving devices cannot use the sequence number to calculate their frame error rate.

【Content of invention】

The wireless local area network device provided in the embodiment of the present invention includes a medium access control layer protocol module for serializing the data units used by the wireless local area network. The MAC layer protocol module includes a list module and a sequence number module. The list module is used to provide the transmission rate of the data unit according to the receiving workstation address of the data unit. The serial number numbering module is used for serial numbering the data units with different receiving workstation addresses and different transmission rates. The serial numbering module includes a counting module library, a first selection module and a second selection module. The counting block library includes several counting blocks. The first selection module is used to receive the data unit and its receiving workstation address, and select at least one counting module from the counting module library according to the receiving workstation address of the data unit, respectively for data units with different transmission rates serial number. The second selection module is used to select a counting module from the counting modules selected by the first selection module according to the current transmission rate of the data unit, and to serialize the data unit.

The frame serial number numbering method provided in the embodiment of the present invention includes the following steps: receiving a data unit and its receiving workstation address and transmission rate; The step of separately serializing the data units of the receiving workstation address and different transmission rates includes the following steps: selecting at least one counting module according to the receiving workstation address of the data unit, for serializing the data units of different transmission rates; and The current transmission rate of the data unit selects a counting module from the above counting modules, and is used to encode the serial number of the data unit.

The wireless local area network device of the present invention serializes the data units with different receiving workstation addresses and different transmission rates separately, and applies the serial numbers to the serial number field of the frame formed by the data units, so that the corresponding receiving device checks the different transmission rates The frame check field of the received frame can calculate the number of correct frames, and then by analyzing the serial number field of the frame received at different transmission rates, the total number of frames received can be calculated, so that the number of frames received at different transmission rates can be calculated frame error rate.

【Description of drawings】

Figure 1 is the MAC data frame format defined by IEEE 802.11.

Figure 2 is the MAC management frame format defined by IEEE 802.11.

FIG. 3 is a structural diagram of a wireless communication system in an embodiment of the present invention.

FIG. 4 is a block diagram of an embodiment of the wireless LAN device of the present invention.

FIG. 5 is a flow chart of data processing by the wireless LAN device of the present invention.

Fig. 6 is a flow chart of the frame sequence number numbering method of the MAC layer protocol module of the present invention.

FIG. 7 is a block diagram of another embodiment of the wireless LAN device of the present invention.

【Detailed ways】

The Open System Interconnect Reference Model (hereinafter referred to as the OSI model) divides the network communication protocol system into seven layers. The bottom layer of the system is the physical layer (Physical Layer, hereinafter referred to as PHY), which defines the medium, transmission method and wiring method. The second layer of the system is the Data Link Layer (Data Link Layer), which defines how to ensure the correct transmission of data, and adds relevant information fields to the data to form a frame. The data link layer includes two sublayers, namely: Logical Link Control (hereinafter referred to as LLC) layer, responsible for sending data to the physical layer correctly, and media access control (Media Access Control, hereinafter referred to as MAC) ) layer, responsible for controlling and connecting the physical medium of the physical layer. The third layer of the system is the network layer (Network Layer), which is responsible for data routing (Routing), including converting addresses, finding the best path and managing traffic. The fourth layer of the system is the transport layer (TransportLayer), which ensures the order and correctness of data arrival. The fifth layer of the system is the session layer (SessionLayer), which defines link dialogue, error handling and logical address name conversion. The sixth layer of the system is the Presentation Layer, which deals with data formats, including format conversion, encryption and decryption, compression and restoration. The seventh layer of the system is the application layer (Application Layer), which defines the interfaces and functions for application program access, as well as directory services and file access.

The IEEE 802.11 standard defines the protocol specifications of the physical layer and the MAC layer, allowing wireless LAN and wireless device manufacturers to establish interoperable network devices within a certain range. The MAC layer of IEEE 802.11 must be compatible with the LLC layer to facilitate mutual operation.

Figure 1 is the MAC data frame format defined by IEEE 802.11. MAC data frame 100 includes: frame control field 110, duration/identifier field 120, address 1 field 130, address 2 field 140, address 3 field 150, sequence control field 160, address 4 field 170, frame body field 180, and frame Check field 190. The sequence control field 160 includes two subfields: a segment number (Segment Number) field 161 and a sequence number field (Sequence Number, SN) 162. Figure 2 is the MAC management frame format defined by IEEE 802.11. The MAC management frame 200 includes: frame control field 210 , duration/identifier field 220 , address 1 field 230 , address 2 field 240 , address 3 field 250 , sequence control field 260 , frame body field 280 and frame check field 290 . The sequence control field 260 includes two subfields: a segment number field 261 and a sequence number field 262 .

As shown in Figures 1 and 2, the address 1 domains 130 and 230 are the receiving workstation address (ReceiverAddress, RA) domain, that is, the MAC service data unit (MAC Service Data Unit, MSDU) or MAC management protocol data unit ( MAC Management Protocol Data Unit, MMPDU) receiving workstation address. The receiving station address is composed of 48 bits. Different receiving station addresses correspond to different receiving stations. The address "FF:FF:FF:FF:FF:FF" is the broadcast address. The sequence control field 160 , 260 includes two subfields: a segment number field 161 , 261 and a sequence number field 162 , 262 . The sequence number is the sequence number of the MSDU or MMPDU carried by the frame. Each MSDU or MMPDU has a sequence number whose value ranges from 0 to 4095.

FIG. 3 is a structural diagram of a wireless communication system in an embodiment of the present invention. In this embodiment, the wireless communication system includes a plurality of wireless LAN devices 1000 , 2000 and 3000 . In this embodiment, the wireless LAN device 1000 transmits data to a plurality of wireless LAN devices 2000, 3000, and can transmit broadcast data.

FIG. 4 is a block diagram of an embodiment of the wireless LAN device 1000 of the present invention. In this embodiment, the wireless LAN device 1000 includes: a high layer protocol module 1100 , a MAC layer protocol module 1200 and a physical layer protocol module 1300 . The high-level protocol module 1100 is used to execute the functions of the protocol layers such as application layer, presentation layer, conversation layer, transport layer, network layer and LLC layer in OSI, convert the transmitted data into MSDU, and transmit the MSDU and its receiving workstation address to MAC layer protocol module 1200.

The MAC layer protocol module 1200 includes: a data interface 1210 , a serial number numbering module 1220 , a MAC processing module 1230 and a list module 1240 . The list module 1240 includes a receiving station address (RA) and transmission rate (TX Rate) list, which is used to provide the transmission rate of the data unit according to the receiving station address of the data unit. The data interface 1210 is used to receive the MSDU and the address of the receiving workstation from the high layer protocol module 1100 and transmit it to the serial number module 1220 . The MAC processing module 1230 is used to generate an MMPDU and its receiving workstation address according to management requirements, and send it to the sequence numbering module 1220 . The MAC processing module 1230 also provides the current transmission rate to the sequence number module 1220 according to the list module 1240 .

The serial numbering module 1220 is used for separately numbering the data units with different receiving workstation addresses and different transmission rates. In this embodiment, the serial number numbering module 1240 receives the MSDU and its receiving workstation address from the data interface 1210, receives the MMPDU and its receiving workstation address from the MAC processing module 1230, and receives the current transmission rate from the MAC processing module 1230. To serial number the received MSDU and MMPDU.

The serial number numbering module 1220 includes: a first selection module 1221 , a second selection module 1222 , a counting module library 1223 , a judging module 1224 and a setting module 1225 . The counting module library 1223 provides multiple counting modules, for example: a first counting module 1223a, a second counting module 1223b . . . an Nth counting module 1223n. The first selection module 1221 is used to receive the data unit and its workstation address, and select at least one counting module from the counting module library 1223 according to the receiving workstation address of the data unit, to serialize the data units with different transmission rates respectively. In this embodiment, the first selection module 1221 receives the MSDU and its receiving workstation address from the data interface 1210, and receives the MMPDU and its receiving workstation address from the MAC processing module 1230. Select at least one counting module from the library 1223, and inform the second selection module 1222 of the selected counting module. The second selection module 1222 is configured to select a counting module from the counting modules selected by the first selection module 1221 according to the transmission rate of the data unit, for serializing the data unit. In this embodiment, the second selection module 1222 selects a counting module from the counting modules selected by the first selection module 1221 according to the current transmission rate provided by the MAC processing module 1230, and is used to encode the received data unit serial number. The judging module 1224 is used for judging whether the serial number programmed by the counting module selected by the second selecting module 1222 is less than a preset boundary value. If so, the setting module 1225 sets the serial number of the received data unit to the serial number compiled by the counting module; if not, the setting module 1225 sets the serial number of the received data unit to the default serial number . The setting module 1225 is also used to update the counting module library 1223 .

The MAC processing module 1230 is used for applying the sequence number set by the setting module 1225 to the data unit. In this embodiment, the MAC processing module 1230 adds relevant information domains to MSDU and MMPDU to form a MAC agreement data unit (MAC Protocol Data Unit, MPDU), that is, a frame, and serial number module 1220 compiles the MSDU and MMPDU The sequence number of is applied to the sequence number field of the formed MPDU (such as the sequence number field 161, 162 shown in FIG. 1 and FIG. 2 above).

The physical layer protocol module 1300 is used to add another related information field to the MPDU formed by the MAC layer protocol module 1200 to form a physical layer protocol data unit (PHY Protocol dataUnit, PPDU), and transmit the PPDU.

FIG. 5 is a flow chart of data processing by the wireless LAN device 1000 of the present invention. In this embodiment, when the wireless LAN device 1000 transmits data to multiple wireless LAN devices 2000, 3000, and transmits broadcast data, the transmitted data must be processed by the OSI seven-layer protocol before being transmitted.

In step S500, the high-level protocol module 1100 processes the transmitted data, executes the functions of protocol layers such as application layer, presentation layer, conversation layer, transport layer, network layer and LLC layer in OSI, and converts the transmitted data into MSDU , and transmit the MSDU and the address of the receiving workstation to the MAC layer protocol module 1200 .

In step S502, the MAC layer protocol module 1200 receives the MSDU and its receiving workstation address from the high layer protocol module 1100, and generates an MMPDU and its receiving workstation address according to management requirements. The MAC layer protocol module 1200 adds relevant information fields such as frame control to the received MSDU and the generated MMPDU to form an MPDU, and sends the formed MPDU to the physical layer protocol module 1300 . The specific operation process is shown in Figure 6.

In step S504, the physical layer protocol module 1300 receives the MPDU from the MAC layer protocol module 1200, adds another relevant information field to the MPDU to form a PPDU, and then sends the PPDU.

Fig. 6 is a flow chart of the method for numbering the frame sequence number of the MAC layer protocol module of the present invention.

In step S600 , the data interface 1210 receives the MSDU and its receiving station address (RA) from the high layer protocol module 1100 , and transmits it to the first selection module 1221 of the serial numbering module 1220 . The MAC processing module 1230 generates an MMPDU and its receiving station address (RA) according to management requirements, and sends it to the first selection module 1221 of the serial numbering module 1220 . The generated MMPDU helps to connect before connecting, or as a notification of disconnection after connecting.

In step S602, after the first selection module 1221 receives the data unit MSDU and its receiving station address, and the data unit MMPDU and its receiving station address, select at least one from the counting module library 1223 according to the receiving station address of the received data unit The counting modules are respectively used to serialize the data units of different transmission rates. It should be noted that the number of counting modules is determined according to the type of transmission rate. In this embodiment, the address of the receiving workstation of the received data unit indicates that the data unit is to be transmitted to the wireless LAN device 2000. Both the wireless LAN devices 1000 and 2000 support four transmission rates of 11Mbps, 5.5Mbps, 2Mbps, and 1Mbps. Therefore, , need to select four counting modules. In other implementations, if the WLAN device 1000, 2000 can support more transmission rates, the number of counting modules is selected accordingly. If the received data unit indicates that the data unit is to be transmitted to other WLAN devices, then select other counting modules accordingly.

In step S604, the MAC processing module 1230 provides the current transmission rate to the second selection module 1222 according to the list module. The second selection module 1222 selects a counting module from the counting modules selected by the first selection module 1222 according to the provided current transmission rate. In this embodiment, the counting module selected by the second selection module 1222 according to the provided current transmission rate is the first counting module 1223a.

In step S606, the first counting module 1223a encodes the serial number (SN) of the received data unit according to a function. In this embodiment, the function is F(x)=4x+1, where x is defined as the sequence of data units transmitted to the wireless LAN device 2000 at the current transmission rate, so the data units transmitted to the wireless LAN device 2000 at the current transmission rate The sequence number of the first data unit is 5, the second is 9, and so on. In other implementations, the above functions may be other linear functions or other types of functions.

In step S608, the judging module 1224 judges whether the serial number (SN) programmed by the first counting module 1223a is smaller than a preset boundary value. In this embodiment, the preset boundary value is 4096.

If it is less than the preset boundary value, in step S610, the setting module 1225 sets the serial number of the data unit as the serial number (SN) programmed by the first counting module 1223a. In this embodiment, the serial number of the data unit is set as the serial number programmed by the first counting module 1223a.

If it is not less than the preset boundary value, step S612 is executed, and the setting module 1225 sets the serial number of the data unit as a predetermined serial number. In this embodiment, the predetermined sequence number is 0.

In step S614, the setting module 150 updates the counting modules in the counting module library 1223 according to the setting result in step S610 or S612. In this embodiment, the setting module 1225 updates the first counting module 1223a. The setting module 1225 transmits the data unit and its receiving workstation address and programmed serial number to the MAC processing module 1230 .

In step S616, the MAC processing module 1230 receives the data unit and its receiving workstation address and the programmed serial number, and adds relevant information domains such as frame control to the received data unit to form an MPDU, and sets the data unit 1225 to the data The sequence number set by the unit is applied to the sequence number field of the formed MPDU, and then the MPDU is sent to the physical layer protocol module 1300 .

FIG. 7 is a block diagram of another embodiment of the wireless local area network device of the present invention. In this embodiment, in the MAC layer protocol module 1200, the difference from the above-mentioned embodiments is that the MAC processing module 1230 first receives the MSDU and the address of the receiving workstation from the high-level protocol module 1100 through the data interface 1210, and generates an MMPDU according to management requirements and its receiving workstation address. The MAC processing layer 1230 adds the relevant information fields to the received MSDU and the generated MMPDU to form an MPDU, and sends it to the sequence numbering module 1220 . In this embodiment, the added related information field includes a sequence number field, so the sequence number numbering module 1220 updates the sequence number field of the formed MPDU.

In other implementation manners, the relevant information field added by the MAC processing module 1230 does not include the sequence number field, and the numbering module 1220 codes the sequence number field on the formed MPDU. Then, the serial number numbering module 1220 transmits the formed MPDU to the physical layer protocol module 1300 . The functions of other constituent elements of this embodiment are the same as those of the previous embodiment, so they will not be repeated here.

The wireless local area network device of the present invention serializes the data units of different receiving workstation addresses and different transmission rates separately, and applies them to the serial number field of the formed MPDU, and the corresponding receiving device checks the frame verification of the MPDU received at different transmission rates Field (FCS) can calculate the correct number of MPDUs, and then by analyzing the serial number fields of MPDUs received at different transmission rates, the total number of MPDUs received can be calculated, so that the error rate of MPDUs at different transmission rates can be obtained ( Frame Error Rate, FER), that is, the frame error rate, its calculation formula is:

FER = number of wrong MPDUs/total number of received MPDUs;

That is, FER=(total number of received MPDUs−number of correct MPDUs)/total number of received MPDUs.

Therefore, the relationship between transmission rate (TX Rate) and frame error rate (FER) can be determined. The receiving device reports the relationship between the transmission rate and FER to the transmitting device, which can be used as a reference factor for the transmitting device to adjust the transmission rate. In this embodiment, the function of the first counting module 1223a used by the serial number numbering module 1220 is F(x)=4x+1. Therefore, if the serial number does not exceed 4095, the total number of received MPDUs can be calculated by the following mathematical formula:

The total number of received MPDUs=(SN of the last MPDU-SN of the first MPDU)/4+1;

If the sequence number exceeds 4095, calculate the number of MPDUs received by segmenting from 0-4095, and then sum them up to calculate the total number of MPDUs received. Thus, the FER at different transmission rates can be calculated.

Claims (12)

1. A frame sequence numbering method is used to sequence the data unit used by the wireless local area network, and it is characterized in that the frame sequence numbering method comprises: Receive data units and their receiving station addresses and transmission rates; and Separate serial numbers for data units with different receiving workstation addresses and different transmission rates, including: Selecting at least one counting module according to the address of the receiving workstation of the data unit, for serializing data units with different transmission rates; and A counting module is selected from the above-mentioned counting modules according to the current transmission rate of the data unit, and is used for serializing the data unit. 2. The frame sequence numbering method as claimed in claim 1, wherein the data unit comprises a media access control management protocol data unit and a media access control service data unit. 3. The frame serial number numbering method as claimed in claim 1, characterized in that: the step of separately numbering the data units of different receiving workstation addresses and different transmission rates also includes the following steps: judging whether the serial number programmed by the counting module selected according to the transmission rate of the data unit is smaller than a preset boundary value; and If it is smaller than the preset boundary value, set the serial number of the data unit as the serial number programmed by the counting module selected according to the transmission rate of the data unit. 4. The frame serial number numbering method as claimed in claim 3, characterized in that: it further comprises the following steps: if the serial number compiled by the counting module selected according to the transmission rate of the data unit is not less than the preset boundary value, then set the serial number of the data unit as the default serial number. 5. The method for numbering frame serial numbers as claimed in claim 1, further comprising the step of: applying the programmed serial numbers to said data units. 6. The frame sequence numbering method according to claim 1, characterized in that: the quantity of at least one counting module selected according to the address of the receiving workstation of the data unit is determined according to the type of transmission rate. 7. A wireless local area network device, comprising a media access control layer protocol module, used to serialize the data units used by the wireless local area network, characterized in that the media access control layer protocol module includes: a list module, configured to provide a transmission rate of the data unit according to the receiving workstation address of the data unit; and The serial number numbering module is used to serialize the data units with different receiving workstation addresses and different transmission rates separately, and the serial number numbering module includes: Counting module library, including multiple counting modules; The first selection module is used to receive the data unit and its receiving workstation address, and select at least one counting module from the counting module library according to the receiving workstation address of the data unit, respectively for data with different transmission rates unit serial number; and The second selection module is configured to select a counting module from the counting modules selected by the first selection module according to the current transmission rate of the data unit, and to serialize the data unit. 8. The wireless local area network device as claimed in claim 7, wherein the data unit comprises a media access control management protocol data unit and a media access control service data unit. 9. The wireless local area network device as claimed in claim 7, wherein: the serial number numbering module further includes a judging module for judging whether the serial number edited by the counting module selected by the second selection module is less than a preset Set the boundary value. 10. The wireless local area network device as claimed in claim 9, wherein the serial number numbering module further comprises a setting module for setting a serial number for the data unit according to the determination result of the determination module. 11. The wireless local area network device according to claim 10, wherein the serial number numbering module further includes a media access control processing module for applying the serial number set by the setting module to the data unit. 12. The wireless local area network device as claimed in claim 7, wherein the number of at least one counting module selected by the first selection module is determined according to the type of transmission rate.

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