KR101234905B1 - Method and apparatus of emulation in wireless data communication network - Google Patents

Abstract

The present invention relates to a method and apparatus for emulating a plurality of virtual devices such that one physical system has a plurality of unique device IDs.

A terminal device connected to a wireless network through at least one access point supporting at least one wireless standard according to the present invention includes: a plurality of virtual terminals implemented in the device for communicating with the access point; A physical layer processor for receiving a frame from an access point and transmitting the frame to an LMAC layer processor, and transmitting a frame transmitted from the lower MAC layer to the access point, from the physical layer processor An interfacing providing an interface between the lower MAC layer processing unit and the lower MAC layer processing unit and the virtual terminals by checking a receiving address of a received frame and checking whether the receiving address corresponds to a receiving address of the terminal. Means;

Wireless LAN, Virtual LAN, IEEE 802.11, Medium Access Control (MAC), Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA)

Description

Emulation method and apparatus thereof in wireless data communication network {METHOD AND APPARATUS OF EMULATION IN WIRELESS DATA COMMUNICATION NETWORK}

1 is a diagram illustrating a network configuration of a general wireless LAN,

2 is a diagram illustrating an interval and a waiting window of data frames in a typical WLAN;

FIG. 3 illustrates the settings of a Request To Send (RTS) / Clear To Send (CTS) / Data / ACK frame and a Network Allocation Vector (NAV) used in a typical wireless LAN.

4 is a diagram illustrating a basic structure of a frame used in a MAC protocol layer of a general wireless LAN of the IEEE 802.11 scheme;

FIG. 5 is a diagram illustrating a relationship between virtual STAs and APs using an emulator implemented according to an embodiment of the present invention; FIG.

6 is a conceptual diagram illustrating a process of performing communication by accessing a plurality of APs to virtual STAs implemented in one terminal using VISTA proposed by the present invention;

7 is a block diagram of VISTA, which is an emulator for emulating a wireless data communication system according to an embodiment of the present invention;

8A is a block diagram of a lower MAC layer processing unit according to a first embodiment of the present invention;

8B is a configuration diagram of an address array table according to a first embodiment of the present invention;

9 is a block diagram of a lower MAC layer processing unit according to a second embodiment of the present invention;

10 is a flowchart illustrating a method for transmitting a frame received in a lower MAC (LMAC) to virtual STAs according to an embodiment of the present invention.

The present invention relates to an emulation method and apparatus for measuring performance in a communication system, and more particularly, to an emulation method and apparatus for measuring performance of a wireless data communication system by implementing virtual terminals in one test equipment in a wireless data communication system. will be.

In general, emulation refers to a technique that uses a special program or mechanical method to make a hardware or software function the same as other hardware or software.

The wireless data communication system is a system developed for a case where a fixed wired network cannot be connected to a terminal. Representative examples of such a wireless data communication system include a mobile communication system, a wireless LAN, Wibro, a mobile ad hoc, and the like.

Among the wireless data communication systems, the most actively developed communication technology in the world is wireless LAN technology. WLAN is a flexible data communication system implemented as an extension or alternative to wired LAN. Wireless LAN uses radio frequency (RF) or infrared technology to transmit or receive data over the air without cable connection, access to the Internet by accessing an access point (AP), and between users Networking is possible. An example of the wireless LAN system may include the Institute of Electrical and Electronics Engineers (IEEE) 802.11 based WiFi (Wireless Fidelity).

In the following specification, an IEEE 802.11 based wireless LAN system will be described as an example, and the terms and the conventional techniques mentioned in the present specification are described in detail in ISO / IEC 8802-11, "Local And Metropolitan Area Networks: Wireless LAN", 1999 Edition. It is.

1 is a diagram illustrating a network configuration of a general wireless LAN. The unit network 100 as shown in FIG. 1 is called a basic service set (BSS), and includes one AP 102 and a plurality of terminals (STAs) 104. The AP 102 includes a DS (Distribution System) that is connected to a wired network or another BSS as shown by reference numeral 106 so that STAs within the BSS can communicate with an external network. As such, the network in which the AP 102 corresponding to the base station configures the BSS is referred to as an 'infrastructure' network. In addition to the infrastructure network, IEEE 802.11 can be configured as an independence basic service set (IBSS) or ad-hoc network, which forms a network between STAs without an AP 102 and can directly exchange data. to be.

Currently, the most widely used wireless LAN devices are in accordance with the IEEE 802.11 Wireless LAN standard, which is a physical layer (PHY) and media access control of the AP 102 and the STA 104. It describes the detailed specifications for the MAC layer. There are various PHY layers, such as frequency-hopping spread spectrum (FHSS), direct sequence spread spectrum (DSSS), infrared (IR), or orthogonal frequency division multiplexing (OFDM). Refers to an RF (Radio Frequency) unit for transmitting and receiving a portion and a radio wave. The MAC layer is a logical layer that operates almost regardless of the type of PHY layer. Authentication, Subscription, Deauthentication, Disassociation, Distribution, Integration, and Privacy ), Reassociation, and delivery of MAC Service Data Unit (MSDU).

The IEEE 802.11 MAC uses a technology called carrier sense multiple access with collision avoidance (CSMA / CA) in a manner that a plurality of terminals use a shared medium called wireless medium (WM) to control access to the shared medium. This technique is a type of time division multiple access (TDMA), that is, a time division multiple access scheme, in which a plurality of terminals use the same frequency band but allow each terminal to transmit and receive a frame through WM at different times. Detailed functions for implementing CSMA / CA of IEEE 802.11 MAC include a Distributed Coordination Function (DCF) and a Point Coordination Function (PCF). Among them, PCF is an option, and most of the products to date do not support this function.

DCF, which is the core of the IEEE 802.11 based MAC protocol, checks whether the WM is occupied before transmitting the data when multiple wireless terminals access the WM, and if the medium is idle, avoid collision. It is a medium approach that transmits after random backoff for random time, but uses MAC-level acknowledgment and retransmission. At this time, the time interval between the data frames occupying the WM should comply with the specification.

FIG. 2 is a diagram illustrating an interval and a standby window of data frames in a typical WLAN, and FIG. 3 is a request to send (RTS) / clear to send (CTS) / data / ACK frame and a NAV (used in a typical WLAN). Network Allocation Vector) is shown. Prior to data transmission, the transmitting terminal sets and transmits an NAV value indicating the occupancy period on the radio channel to the RTS. The receiving side confirms that there is a communication request to itself, and sends a CTS to confirm the response. When the sender receives the CTS response, it starts to transmit the prepared data and waits for an ACK from the receiver after the transmission is completed. If there is no error in the received data, the receiver sends an ACK to the transmitter to inform that the data has been successfully received.

Referring to FIG. 2, in the IEEE 802.11 standard, a time interval between the data frames is referred to as an inter-frame space (IFS), and the time interval is a short inter-frame space (SIFS) 200 according to a length, and a PIFS ( PCF Inter-Frame Space (202), DCF Inter-Frame Space (DIFS) 204, and not shown, but divided into Extended Inter-Frame Space (EIFS).

Among these, the SIFS 200 is an interval used when a receiving terminal requests a response immediately from a device having a receiver address (RA) of a frame and corresponding to a transmitter address (TA), and the other terminal. It has the effect of occupying WM first. A representative example in which the SIFS 200 is used is a case in which a MAC Protocol Data Unit (MPDU) frame set as itself, that is, a receiving terminal, is transmitted, and an acknowledgment (ACK) frame is transmitted to a device corresponding to a TA. ) And the ACK frame 302 is spaced as much as the SIFS (200).

3 shows the ACK frame 302 from the destination device 306 to the source device 304 after the SIFS 200 after the data frame 300 from the source device 304 to the destination device 306 is completed. An example of transmitting is shown.

4 is a diagram illustrating a basic structure of a frame used in a MAC protocol layer of a general wireless LAN of the IEEE 802.11 scheme.

In FIG. 4, the frame control field 400 indicates the version of the MAC protocol and the type of frame. The type of the frame is largely divided into a management frame, a control frame, and a data frame, and each of the frames is subdivided into subtypes. The Duration / ID field 402 mainly records time information about how long WM will be occupied after this frame, and the Address Fields 404 are RA addresses. ), TA (Transmitter Address), DA (Destination Address) and SA (Source Address). Here, the address (Address) is the same structure as the MAC address of the Ethernet, for example, six bytes of data, all Ethernet devices have a unique MAC address. In FIG. 4, a recipient address RA for receiving a frame is stored in the address 1 408 field. Finally, the Frame Check Sequence (FCS) field records the results of the Cyclic Redundancy Code (CRC) calculation for the end of the frame body from the frame control field 400, so that the receiver calculates the CRC in the same way. It is used to check whether the frame contents are deformed while being transmitted by comparing with the FCS field value attached to the.

The wireless data communication technology such as the above-described wireless LAN is one of the most actively developed communication technologies worldwide. In particular, the wireless LAN field has an explosive increase in the user base since the commercial product was recently released, especially in the IEEE 802.11 standard. In addition, wireless communication technology in the MAN or WAN field is rapidly progressing. As a result, numerous companies and research institutes are developing wireless data communication equipment, and educational institutions such as universities are taking courses on these technologies.

However, despite the development of such wireless data communication technology, there is a lack of a basis for experiments or training for acquiring wireless communication technology or for operation test of a developed communication protocol. An IEEE 802.11 WLAN having the thickest user layer will be described with reference to FIG. 1 as an example.

 Several wireless terminals (station STAs), such as notebook computers, connect to an access point (AP) connected to a wired network to use the Internet. Referring to FIG. 1, one commercial AP 102 may simultaneously associate at least 10 to as many as 100 or more STAs 104 according to a model. However, it is very difficult to actually mobilize 100 or more STAs for the boundary condition or stress test of the AP. Nevertheless, the AP 102 installed in a public place may have a large number of concurrent subscribers, and even in such a case, it is necessary to maintain a high level of reliability. For example, the AP developer must prepare a large number of STAs to test the operation when the maximum STAs accessible to the AP are simultaneously connected. Since typical STAs are notebook computers, it is actually very difficult to mobilize them for more than a few decades. Even if many test STAs are provided, it is more difficult to artificially manipulate each STA to generate an event to be tested in the AP.

The present invention provides an emulation apparatus and method for testing the operation of a system in a wireless data communication system.

The present invention provides an apparatus and method capable of emulating a plurality of data communication virtual terminals with a terminal having one physical layer in a wireless data communication system.

A terminal device connected to a wireless network through at least one access point supporting at least one wireless standard according to the present invention includes: a plurality of virtual terminals implemented in the device for communicating with the access point; A physical layer processor for receiving a frame from an access point and transmitting the frame to an LMAC layer processor, and transmitting a frame transmitted from the lower MAC layer to the access point, from the physical layer processor An interfacing means for providing an interface between the lower MAC layer processing unit and the virtual terminals by examining a receiving address of a received frame and checking whether the receiving address corresponds to a receiving address of the terminal; It includes.

A method for connecting to a wireless network through at least one access point supporting at least one wireless standard according to the present invention includes: implementing at least one virtual terminal to test the performance of the wireless data communication system; Receiving a data frame from the access point, checking whether a receiver address of the received data frame is the same as a MAC address of the implemented virtual terminals, and if the check result is the same, And transmitting an ACK frame to the point.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same components in the figures represent the same numerals wherever possible. Specific details are set forth below, which are provided to aid a more general understanding of the present invention. In describing the present invention, when it is determined that description of related known functions or configurations may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

First, the concept of the present invention will be briefly described below before describing the present invention. The present invention relates to a MAC protocol in a communication network that transmits and receives data wirelessly between one base station and a plurality of terminals. In a wireless area network (WAN) and similar applications, a method and apparatus are provided for providing a basis for emulating a plurality of data communication virtual terminals with a terminal having one network card. When the emulator proposed in the present invention is defined as VISTA, the virtual STAs implemented in the VISTA may have a plurality of MAC addresses.

The apparatus for emulating a plurality of data communication virtual terminals as a terminal having a single physical layer as in the present invention can be directly used for testing a real operating situation at low cost in a communication network as well as wireless network test software or wireless network analysis. It can be applied as hardware for software or as a development toolkit required to implement a standard MAC protocol or a new MAC protocol. FIG. 5 illustrates a virtual STA using an emulator implemented according to an embodiment of the present invention. Is a diagram illustrating a relationship between the APs and the AP.

In the present specification, for convenience of description, the name of the emulator proposed by the present invention will be referred to as VISTA (Virtual Station). Herein, the UEs virtually implemented in the VISTA will be referred to as a 'virtual STA', and the virtual STA may be a standard MAC layer protocol, a wireless network analysis tool, or a test tool for testing an AP or other STAs. Can lose.

The virtual STA may be an application program implemented in software to be implemented in another computer connected to the inside of the emulator or a wired network.

In FIG. 5, ten virtual STAs 500a to 500e and 502a to 502e are emulated using two VISTAs 500 and 502. Each of the VISTAs 500 and 502 may be operated in a notebook computer that can access a general wireless LAN or a wireless terminal that performs a similar function, and may be directly implemented in the AP 102 for testing.

Since there is no limit to the number of virtual STAs that can access one VISTA, tens or more virtual STAs can be emulated in one VISTA. When only one VISTA is used, emulation is performed using a plurality of VISTAs as shown in FIG. 5 because contention of the wireless section cannot be induced.

FIG. 6 is a diagram conceptualizing a process in which virtual STAs implemented in one UE access a plurality of APs and perform communication using VISTA proposed in the present invention.

FIG. 6 illustrates a case in which three virtual STAs 600a, 600b, and 600c are emulated using one VISTA 600 to access different BSSs 602, 604, and 606. This type of connection is necessary when one terminal joins multiple virtual LANs and uses different network services.

For example, Basic Service Set (BSS) 1 (602) is a guest LAN that is open to outsiders, BSS 2 (604) is a LAN for Office Automation (OA) Intranet, and BSS 3 (606) is a LAN for research and development. Let's assume If the configuration is as described above, each WLAN is classified according to its purpose. Using a wireless terminal with VISTA functionality, users can simultaneously access BSS 1 (602), BSS 2 (604), and BSS 3 (606) and, if necessary, public sites connected to the guest LAN without reconfiguring network information. You can update the information or test the development system by connecting to the Intranet and conducting office-related processing. Of course, at this time, the virtual emulation clients of the VISTA terminal are connected to each BSS with different security level, so that the network itself is not leaked except for the VISTA client connected to the same level from other terminals in one BSS. This has the advantage of maintaining security. Here, the virtual emulation client refers to a virtual network interface from a network user's point of view, which allows a user to simultaneously connect to multiple networks of different security levels using a single wireless network card. .

In addition, by using the multiple virtual terminal emulation capability of the present invention, it is possible to simultaneously use a single wireless terminal connected to different wireless LAN or WLAN according to the needs of security or performance. For example, a user can access an office network using a single wireless terminal card having a VISTA function and perform research and development by accessing a secure infrastructure network at the same time while viewing general business. That is, according to an exemplary embodiment of the present invention, a user may connect and use one WLAN card to several virtual LANs simultaneously. This enables access control at the network level depending on whether the terminal is connected to each wireless VLAN or not.

This logical network configuration can be considered regardless of the RF channel configuration. In particular, when multiple APs configure different BSSs on the same RF channel, a system having only one RF transceiver may simultaneously connect to multiple WLANs by applying the VISTA function.

In addition, in FIG. 6, the concept of VISTA is applied only to the STA, but may also be applied to the AP. That is, VISTA can be configured to emulate a plurality of APs in one hardware system, and can be applied to a wireless LAN system development test and a plurality of independent BSSs.

7 is a block diagram of a VISTA 700 which is an emulator for emulating a wireless data communication system according to an embodiment of the present invention. The emulator 700 proposed by the present invention includes a baseband processor (BBP) 702b and an RF unit 702a in a wireless communication device such as an STA described above. Low MAC layer processing unit 704 and the physical layer for processing a time critical portion such as SIFS (eg, 16 microseconds in 11a and 10 microseconds in 11b / 11g) of the MAC layer protocols. Terminal matching to allow multiple virtual STAs to simultaneously access the I / O agent 706 and the I / O agent 706 for directly controlling hardware such as the processor 702 and the lower MAC layer processor 704. A unit (Station Coordinator: STACO) 708, each component will be described in detail below.

In FIG. 7, the emulator VISTA 700 includes four parts. First, a frequency down conversion of the signal received from the AP 102 or a frequency up conversion of the baseband signal to be transmitted to the AP 102 is performed based on a signal received from the RF unit 702a. A physical layer (PHY) processor 702 including a baseband processor (BBP) 702b for converting to a band, and a LMAC (Low MAC) implemented for a time critical part of the MAC protocol I / O agent 706 directly controlling the layer processor, the PHY processor 702, and the LMAC layer processor 704 and the virtual STA 710 virtually generated by the VISTA 700 input / output packets requested for transmission. A terminal matching unit (STACO) 708 for transmitting to the agent 706.

In FIG. 7, the terminal matching unit 708, the input / output agent 706, the PHY layer processing unit 702, and the LMAC layer processing unit 704 are all implemented in one independent target system such as a wireless notebook computer. In practice, the terminal matching unit 708 may operate in another computer host connected through a network. That is, the remote terminal may include an input / output agent, a PHY layer processing unit 702, and an LMAC layer processing unit 704 so that the terminal matching unit operates in a terminal connected through a network such as Ethernet.

Then, a block configuration of VISTA according to an embodiment of the present invention will be described in detail below.

The physical (PHY) layer processing unit 702, which includes the RF unit 702a and the BBP unit 702b, is a physical layer of a standard standard, which conforms to all kinds of physical layers defined in the IEEE 802.11 standard, that is, 2.4 conforming to 802.11 and 802.11b. Frequency Hopping (FH) or Direct Sequence Spread Spectrum (DSSS) and Infra-Red (IR) methods in the GHz band, Orthogonal Frequency Division Multiplexing (OFDM) in the 5 GHz band according to 802.11a, and 2.4 GHz in accordance with 802.11g It includes all Physical (PHY) layers in accordance with High Rate DSSS (HR / DSSS) and Extended Rate PHYs (OFDM-OFDM) and DSSS-OFDM schemes of bands and other wireless communication standards. Accordingly, the configuration of the physical (PHY) layer processing unit 702 varies depending on which standard standard VISTA is applied to, and FIG. 7 assumes that the device operates according to the IEEE 802.11a standard.

The lower MAC (LMAC) layer processing unit 704 implements a part of a sub layer that is responsible for channel access protocol processing among MAC protocol layers, and requires a fast processing speed among MAC protocols, and a MAC layer and a PHY layer not shown. It is in charge of the interface between the processing units 702. The LMAC layer processing unit 704 is responsible for transmitting an ACK frame as an example of processing the MAC protocol. This means that when the terminal A and B communicate with each other when the terminal A determines the destination of the specific frame as the terminal B and the terminal B normally receives the specific frame, the terminal B implements the LMAC in the terminal B. The layer processor responds with a short ACK frame to inform the terminal A of the normal reception result of the specific frame.

In this case, the ACK frame must be transmitted from the terminal B (receiving side) to the terminal A (transmitting side) after a designated short time of the SIFS 200 shown in FIGS. 2 and 3 from the end of the first received frame. In the IEEE 802.11a standard, the SIFS is set to 16 microseconds.

The SIFS 200 time includes a time required for the data frame to pass through the PHY layer processor 702, a time for the ACK frame to pass through the PHY layer processor 702, and a time used by the LMAC layer processor 704. do. The LMAC layer processing unit 704 calculates a cyclic redundancy code (CRC) for the data frame received during the remaining period of time to determine whether it is intact during transmission, and determines whether the recipient address (RA) of the frame is its own address. After comparing and determining whether the frame type needs to respond with an ACK, an ACK frame should be transmitted when an ACK response is required. RA is recorded in Address 1 in FIG. The RA of the received frame refers to the MAC addresses of the virtual STAs 710 virtually implemented in the VISTA 700. The MAC addresses of the virtual STAs 710 are stored in an address storage unit to be described below. That is, a separate physical MAC address is assigned to each virtual STA, so that the VISTA system has a plurality of MAC addresses. For this reason, the LMAC layer processing unit 704 according to the embodiment of the present invention should check whether the plurality of MAC addresses match.

One of the essential parts of the present invention is that the LMAC layer processing unit 704 compares the RA of the frame received from the radio and checks whether the received frame corresponds to its own address. While all the conventional network devices have one unique address, the VISTA according to the embodiment of the present invention has a plurality of addresses, and thus acts like several independent network devices. The LMAC layer processing unit The configuration of 704 will be described with reference to FIGS. 8 and 9 below.

 The input / output agent 706 directly controls and initializes the PHY layer processing unit 702 and the LMAC layer processing unit 704 and initializes the LMAC layer processing unit 704 with a frame requested to be transmitted from the STACO 708. It is transmitted to the WM through, and serves to deliver the frame received from the LMAC layer processing unit 704 to the STACO (708). In this way, appropriate frame queues (not shown) are managed to perform transmission (TX) and reception (RX) so that frames requested for transmission or received frames are not lost. This part may correspond to a network device driver in a general network device, but the difference is that it does not directly handle the work corresponding to the MAC protocol. In other words, if an IEEE 802.11 standard network device driver receives an Ethernet frame request from a higher layer and transforms it into an IEEE 802.11 MAC frame format, or transmits it by creating a higher management frame and transmitting the received management frame, The input / output agent 706 serves as an interface for delivering a frame between the terminal matching unit 708 and the LMAC layer processing unit 704. As such, since the input / output agent 706 has only a simple input / output function, the virtual STAs may directly perform the MAC protocol.

The STACO 708 serves to connect the plurality of virtual STAs to the input / output agent 706, to exchange frames between clients connected to the plurality of virtual STAs, and the plurality of virtual STAs When each frame is to be transmitted through the input / output agent 706, a different time is allocated to synchronize the input / output agent 706 so as not to receive several transmission requests at one time. Here, STA refers to a wireless terminal / network interface defined in the IEEE 802.11 / Wi-Fi standard, and a client refers to a computer using a wireless network interface card.

In addition, the STACO 708 supports a filtering function for the connection between the virtual STAs and the AP or each of the virtual STAs. For example, the virtual STA 1 may specify to receive only the management frame and the virtual STA 2 to receive only the data frame. This function helps the virtual STA to be easily written not only as a terminal but also as wireless network analysis software or automated standard device testing software. Application software such as a virtual STA calls the STACO 708 by calling API (Application Programming Interface) functions provided by the STACO 708 for connection, filtering, or setting an event flag. Easy to use

Implementing this can actually be done by using multiple address array tables, or by masking a portion of a total of six bytes of addresses so that any value can be determined for the masked portion. There can be several ways. Hereinafter, the lower MAC layer processing in the present invention will be described with reference to two embodiments. First, in the first embodiment, the lower MAC layer processor 704 compares a receiver address of a data frame received from the physical (PHY) layer processor 702 with an address stored in an address array table and checks whether the frame corresponds to itself. . In a second embodiment, the lower MAC layer processing unit 704 masks some bits of a receiver address of a data frame received from the physical layer processing unit 702, and masks an address of its own STA. Comparing one bit will be described as a second embodiment.

8A is a block diagram of the LMAC layer processing unit 704 according to the first embodiment of the present invention. 8B is a configuration diagram of an address array table 806 according to the first embodiment of the present invention.

First, the input / output interface 800 is responsible for the interface with the PHY layer processing unit 702 and transfers the data frame received from the physical layer processing unit 702 to the control unit 802, or the ACK frame generated by the control unit 802. Is transmitted to the physical layer processing unit 702.

The controller 802 transfers the RA stored in address 1 of the address field 404 of the MAC header of the data frame received from the input / output interface 800 to the receiver address comparison unit 804. Control to check whether the address of the data frame is clearly correct. If a data frame other than the address corresponding to itself is received or if the CRC result frame is damaged, the data frame is discarded and if the address corresponds to the address, the ACK frame is transmitted or the received frame is processed.

The recipient address comparison unit 804 compares the address of the RA received from the physical layer processing unit 702 with the address array table 806 in which a plurality of six-byte addresses, such as reference number 808, is stored. It checks whether it is the same as one of the addresses stored in the address array table 806 and transmits the check result to the controller 802.

9 is a block diagram of the LMAC layer processing unit 704 according to the second embodiment of the present invention.

In FIG. 9, the same reference numerals are used for the same parts as the above description of the drawings.

The controller 900 transfers the RA stored in the address 1 408 of the address field 404 of the MAC header of the data frame received from the input / output interface 800 to the receiver address comparison unit 904. Control to check whether the address of the received data frame matches its address. The recipient address comparison unit 904 compares the address stored in the address storage unit 902 where the address table corresponding to the MAC address of the virtual STA with the recipient address RA received from the controller 900, or stores the address. Some bits of the address stored in the block 902 are masked and stored in the mask register 906. If bit information of a corresponding position among the masked address and the address of the received frame is the same, the bit is stored in the mask register 906. I think that. That is, the recipient address comparison unit 904 compares a portion of the RA received from the controller 900 with a masked portion of the mask register 906, and receives the masked portion from the control unit 900 as a result of the comparison. If a given RA matches, it is recognized as the address corresponding to it. Masking in the present invention means an operation of ANDing binary "1" by the corresponding number of bits to compare only a part of address bits of virtual STAs stored in the address storage unit 902, that is, to select only a portion of interest. . For example, if the original data is 010100101 and bit masking with 000001111, the result is 000000101. In other words, the masking only sees the contents of the bits of interest among the entire address bits and recognizes them as its own addresses if the contents match.

In the mask register 906, the recipient address comparison unit 904 masks a part of the address stored in the address storage unit 902, and the masked address is stored. In more detail, the receiver address comparison unit 904 of the lower MAC layer processing unit 704 may use the addresses '010100101' and '00001111 to mask only the lower 4 bits of the addresses' '010100101' of the virtual STAs. AND is associated with AND, and the result value '0101' is stored in the mask register 906. When the lower 4 bit information of the addresses of the frames received from the physical layer processor 702 coincides with '0101', it is recognized that the received frames are correctly received by the virtual STAs. That is, the lower 4 bits are the bits of interest, and if the lower 4 bits of the address of the received frame is '0101', it is recognized as its own address.

8 and 9 are clearly different from the monitoring (or capture) technique using "promiscuous mode" or "pattern matching" provided by general commercial network devices. Unlike the passive monitoring technique, VISTA performs active processing such as ACK and CTS, thus creating the same traffic conditions as the actual network conditions.

The lower MAC layer processor 704 may be implemented in software or hardware. In the present invention, the lower MAC layer processor 704 is implemented in hardware for convenience of description.

Similarly, in the above-described embodiment, the Ethernet MAC address of 6 bytes in length is used as the unique identification number of the network device. However, even if the address is changed, the basic concept that one network device has multiple unique identification numbers is the same. Can be applied. That is, the same concept can be applied to a network having a 20 byte length such as an IP network address.

10 is a flowchart illustrating a method for transmitting a frame received by a lower MAC (LMAC) layer processor 704 to virtual STAs according to an embodiment of the present invention.

First, in step 1000, the LMAC layer processor 704 receives a data frame from the physical layer 702 and performs a CRC calculation on the received data frame in step 1002 to check whether the received frame is damaged in step 1004. do.

In step 1004, if the received frame is damaged, the LMAC layer processing unit 704 proceeds to step 1006 and discards the received data frame. On the other hand, if the frame is not lost in step 1004, in step 1008, the LMAC layer processing unit 704 checks whether the frame receiver address is the same as its own address, and if not, proceeds to step 1006 to receive the received datagram. Discard. In step 1008, it is determined whether the destination address of the received frame is the same as its own address. In step 1008, as in the first embodiment, the receiver address of the received frame and the addresses stored in the address array table 806 may be compared to determine whether the address is the same receiver address, and as shown in FIG. 9. According to an exemplary embodiment, a part of the received frame may be compared with the masked part to check whether the corresponding frame is a data frame corresponding to the masked part. Herein, the RA of the received frame means MAC addresses of virtual STAs virtually implemented in VISTA. The MAC addresses of these virtual STAs are stored in the address storage unit 902 described above. That is, a separate physical MAC layer address is assigned to each virtual STA, and therefore, since the VISTA system has a plurality of MAC layer addresses, the LMAC layer processing unit 704 according to an embodiment of the present invention is assigned to the plurality of MAC addresses. Checks for a match.

In step 1010, the LMAC layer processor 704 determines whether to transmit an ACK frame in response to the received data frame. If the ACK frame needs to be transmitted in step 1010, the LMAC layer processing unit 704 proceeds to step 1012 and transmits the ACK frame.

As described above, in the present specification, the embodiment has been described as being applied to the IEEE 802.11 Wireless LAN standard so that the operation principle and technology can be accurately and easily understood. However, the present invention provides a data frame using a short response frame called an acknowledgment (ACK). It can be applied to all systems using the MAC protocol of the method of acknowledging the reception of the.

As described above, the present invention relates to a virtual STA emulator capable of substituting several STAs with one device having an AP level of complexity, and the virtual STAs are implemented in software to be implemented in an emulator or other computers connected to a wired network. The virtual STA may be driven and a plurality of virtual STAs may be performed in one computer.

As described above, according to the present invention, the virtual STAs may be implemented in software and run on other computers connected to the inside of the emulator or a wired network. And the cost of creating a test environment.

In addition, according to the present invention, the developer and operator can verify the reliability of the product to the customer since it is possible to check in advance whether the communication protocol implemented by the developer operates in an actual communication system or is compatible with commercial products.

Claims (16)

An emulation apparatus in a wireless data communication system, The emulation device is connected to the wireless network through at least one access point supporting at least one wireless standard, The emulation device, A plurality of virtual terminals, implemented to communicate with the access point; A physical (PHY) layer processor configured to receive a frame from the access point and transmit it to a lower MAC (LMAC) layer processor and to transmit the frame transmitted from the lower MAC (LMAC) layer processor to the access point; A lower MAC (LMAC) layer processing unit configured to check a receiving address of the frame received from the physical layer processing unit to check whether the receiving address corresponds to a receiving address of the terminal; And And interfacing means configured to provide interfacing between the lower MAC layer processor and the virtual terminals. The method according to claim 1, The interfacing means, The physical (PHY) layer processing unit and the lower MAC (LMAC) layer processing unit, and controls the transmission of the transmitted frame to the lower MAC (LMAC) layer processing unit, and received from the lower MAC (LMAC) layer processing unit And an input / output agent configured to send a frame to the virtual terminals. 3. The method of claim 2, The interfacing means, The virtual terminal configured to perform communication with the access point and the input / output agent is connected to the virtual terminal, so that the virtual terminals can transmit and receive frames through the input / output agent Emulation apparatus further comprising a terminal matching unit, configured to control the frame transmission order of the terminals. The method of claim 3, The terminal matching unit emulates different transmission times for each terminal when the virtual terminals transmit frames. The method according to claim 1, The lower MAC layer processing unit, And transmitting an acknowledgment (ACK) frame if the received frame is normal. 6. The method of claim 5, The lower MAC layer processing unit, And an input / output interface for interfacing with the physical layer processing unit. The method according to claim 6, The lower MAC layer processing unit, Emulation apparatus further comprises an address storage means for storing the addresses corresponding to the virtual terminals. 8. The method of claim 7, The lower MAC layer processing unit, And a receiver address comparison unit which compares an address field of a frame received through the input / output interface with an address stored in the address storage means. The method of claim 8, The lower MAC layer processing unit, The receiver address RA stored in the address field of the MAC header of the frame received from the input / output interface is transferred to the receiver address comparison unit, and the receiver address and the address storage means of the received frame are checked as a result of the receiver address comparison unit. And a control unit for transmitting an acknowledgment (ACK) message to the input / output interface if the addresses stored in the addresses of the same match. 8. The method of claim 7, The lower MAC layer processing unit, And a mask register for masking some bits of the address stored in the address storing means as an address of the virtual terminal. The method of claim 10, The lower MAC layer processing unit, And a receiver address comparison unit for checking whether the masked address stored in the address storing means and the bit information of the corresponding position among the addresses of the received data frame are the same. 12. The method of claim 11, The lower MAC layer processing unit, And a control unit which transmits a receiver address (RA) of the data frame received from the input / output interface to the receiver address comparison unit to control whether the address of the received data frame corresponds to the address of the virtual terminals. Device. An emulation method in a wireless data communication system for connecting to a wireless network through at least one access point supporting at least one wireless standard, the method comprising: The method comprises: Implementing at least one virtual terminal to test the performance of the wireless data communication system; Receiving a data frame from the access point; Checking whether a receiver address of the received data frame is the same as a MAC address of the implemented virtual terminals; And And if the address is the same, sending an acknowledgment (ACK) frame to the access point. 14. The method of claim 13, And performing a cyclic redundancy check (CRC) on the received data frame. 14. The method of claim 13, The step of checking whether the receiver address of the received data frame is the same as the MAC address of the virtual terminals, And comparing whether bit information of a corresponding position among the masked addresses of the virtual terminals and the address of the received data frame is the same. 14. The method of claim 13, The step of checking whether the receiver address of the received data frame is the same as the MAC address of the virtual terminals, And comparing a recipient address (RA) stored at an address of an address field of a MAC header of the received frame with an address stored at an address of an address array table.

Images