KR100560742B1 - apparatus and method of processing MSDU in wireless LAN - Google Patents

Abstract

The present invention relates to a method and apparatus for processing a frame in a wireless LAN, wherein a terminal transmitting a frame through a wireless medium according to IEEE 802.11 does not transmit only one frame in one frame transmission opportunity obtained by the terminal. If the frame temporarily stored in the queue and the newly created data have the same source address, destination address, routing information priority, and service class, the payload field of the frame temporarily stored in the queue and the payload field of the newly created data Merge generates one merge frame, transmits a merge frame generated at its own frame transmission opportunity, and transmits a plurality of MSDUs at one transmission opportunity.

IEEE 802.11, Frame, Merge, LLC Logical Link Control Protocol Data Unit (PDU), Physical Layer Convergence Procedure (PLCP)

Description

Method and apparatus for processing Mac service data unit in wireless LAN {apparatus and method of processing MSDU in wireless LAN}             

1 is a view for explaining each hierarchical structure of IEEE 802.11 applied to the present invention.

2 is a flowchart illustrating a message exchange between MAC, PLCP, and PMD when transmitting a frame based on IEEE 802.11 to which the present invention is applied.

3 is a block diagram illustrating a configuration of an apparatus for processing a packet in a wireless LAN according to a preferred embodiment of the present invention.

4 is a flowchart illustrating a method of processing data received by a Mac processor according to an exemplary embodiment of the present invention.

5 is a view for explaining that the pulse processing unit applied to the present invention performs an insulation treatment.

FIG. 6 is a flowchart for explaining the flow of a method for determining whether or not a Mac processor temporarily merges a frame temporarily stored in a queue with a newly generated frame according to the present invention; FIG.

FIG. 7 is a flowchart illustrating a flow of a method in which a mac processor merges one or more frames according to a preferred embodiment of the present invention. FIG.

8 is a view for explaining the structure of a merge frame according to an embodiment of the present invention.

9 is a view for explaining the structure of a frame control field applied to the present invention.

<Explanation of symbols for the main parts of the drawings>

10: host 11: host processor

20: frame processing apparatus 21: central processing unit

21a: Mac processor 21b: PLCP processor

22: cue 23: wireless interface unit

The present invention relates to a method and apparatus for processing a frame in a wireless LAN, and more particularly, when a wireless LAN terminal conforming to IEEE 802.11 has a transmission opportunity and transmits a frame temporarily stored in a queue through a wireless medium, A method and apparatus for processing a frame in a WLAN for merging and transmitting a plurality of frames in a transmission opportunity of the present invention.

IEEE 802.11 is a widely used wireless LAN standard, and defines protocols for the physical layer and medium access control (MAC) constituting the wireless LAN.

This protocol allows devices such as laptops, desktop personal computers (PDAs), personal digital assistants (PDAs) to use the wireless LAN function, and the requirements of the MAC and physical layers defined in the standard. With a wireless LAN adapter (Adapter) that satisfies the matter, it is possible to access the wireless LAN service by accessing the wireless LAN while maintaining compatibility with other devices.

The adapter of each terminal processes the WLAN physical layer corresponding to Layer 1 and the MAC layer corresponding to Layer 2.

In general, the WLAN adapter receives a Protocol Data Unit (PDU) from the upper layer of the MAC layer, processes it as a MAC frame, and temporarily stores the data in a transmission queue (TX_Queue) provided inside the adapter. do.

When the WLAN adapter temporarily stores a frame to be transmitted in the transmission queue, the Mac attempts to transmit the temporarily stored frame, but when the medium to transmit the frame is already busy, That is, when the transmission delay of each terminal becomes longer, a newly received frame is input to the transmission queue at a higher layer, and as a result, a plurality of MAC frames are temporarily stored in the transmission queue and exist in a standby state.

When a wireless LAN adapter has a transmission opportunity according to a distributed coordination function (DCF) method that transmits a frame due to contention or a point coordination function (PCF) method that transmits a frame by polling, it is temporarily placed in a queue. The first frame stored in the queue is transmitted through a wireless medium in the form of an IEEE 802.11 frame.

However, in the current technology, one IEEE 802.11 frame can be transmitted at one transmission opportunity. Therefore, if N frames are temporarily stored in a transmission queue, all frames can be transmitted only after having N transmission opportunities.

In addition, in the past, the traffic of the WLAN was mainly data, but recently, traffic that requires real time, such as voice signals or video signals, is increasing.

In order to be able to perform a traffic application requiring such real-time, a reliable physical channel implementation of a wireless LAN system is required.

In addition, the terminal having the frame to be transmitted should be able to access the wireless medium and transmit the frame with an appropriate transmission delay.

In addition, when a mobile terminal connected to a wireless LAN having an infrastructure structure is in communication with a terminal connected to a wired LAN, a user's voice is transmitted from the mobile terminal to a WLAN access point. The delay may be expressed by Equation 1 below.

Voice delay_air = Packetization delay + Queuing delay + MAC delay

Here, 'Voice delay_air' is a delay that occurs when voice traffic is transmitted to a WLAN access point through a wireless LAN, and 'Packetization delay' is a time when an analog voice signal is generated in the application layer. Delay that occurs when voice traffic is generated and transmitted to Layer 6.

This 'packetization delay' delay depends on the type of voice codec that converts an analog voice signal into voice traffic.

Table 1 below describes 'Packetization delay' according to the type of voice codec.

Codec Bit Rate (Kb / s) frame duration (ms) G.711 64 0 G.729A 8 10 G.723.1 MP-MLQ 6.3 30 G.723.1 ACELP 5.3 30

As described in Table 1, frame duration depends on the type of voice codec, and this frame duration affects Voice delay_air.

That is, when the analog voice signal is coded according to the voice codec 'G.729A', a 'Packetization delay' of '10 ms' occurs, and when the analog voice signal is coded according to the voice codec 'G.723.1 MP-MLQ', 'Packetization delay' of 30ms' occurs.

In addition, the 'Queuing delay' is a delay in which the MAC inputs the received frames from the upper layer to the transmission queue and temporarily stores them until the transmission order of the stored frames is ranked first.

In addition, the 'MAC delay' is a delay that takes place until the transmission is started by the terminal occupies the wireless medium after the frame is temporarily stored in the transmission queue, and its own transmission rank becomes 1st.

The 'MAC delay' refers to a time delay occurring according to the MAC protocol, and includes a time delay due to collision between different terminals.

Assuming that the processing delay occurring through the protocol from Layer 6 to Layer 3 in the 'Voice delay_air' determined by Equation 1 is negligibly small, when transmitting voice traffic in the WLAN The largest portion of the time delay that occurs is the time delay that occurs in the wireless section.

In other words, if each item affects 'Voice delay_air', the 'MAC delay' is shorter than the packetization delay and the packetization delay (that is, before the new frame is entered). If the frame temporarily stored in the 1st transmission priority has a successful transmission opportunity, it can be seen that the 'Queuing delay' becomes '0'.

However, if the packetization delay is set to the minimum (Minimum = Packetization delay_min) to reduce the 'Voice delay_air' delay, the period in which the frame is input to the transmission queue has the same value as the 'Packetization delay_min'.

In order for the Mac to transmit the frame in order not to cause a problem, it has to have a transmission opportunity at the same period as 'Paketization delay_min'.

If the MAC does not have a transmission opportunity in the same period as 'Paketization delay_min', frames in the transmission queue are stacked over time in the transmission queue.

In addition, as the frames input to the transmission queue later in time have a higher 'Queuing delay', the voice call service using the wireless LAN is limited.

In order to prevent such increase in 'queuing delay', 'MAC delay' should be smaller than 'Packetization delay'.

However, in the DCF mode commonly used in WLAN, when a certain amount of load is applied to the wireless medium, the 'MAC delay' is increased to tens of ms or hundreds of ms. As a result, the existing wireless system has a problem that the number of terminals being accessed is strictly limited despite the bandwidth.

That is, as the wireless medium becomes in a high load condition, the 'MAC delay' of each terminal becomes longer, and the 'MAC delay' of the terminal becomes longer than the average period of the frame in which the upper layer enters the MAC layer. If so, a plurality of frames are stacked in the transmission queue of the terminal, so that the 'Queuing delay' increases as the frame is temporarily stored at the rear of the transmission queue.

This increase in 'queuing delay' limits the implementation of services requiring real time.

Therefore, the present invention was devised to solve the above problems, and if the MAC of the WLAN has a frame transmission opportunity, it does not transmit one frame received from a higher layer through a wireless medium, but rather is a part of the IEEE 802.11 protocol. It is an object of the present invention to provide a method and apparatus for processing a frame in a wireless LAN that can provide a wireless LAN service more efficiently by transmitting a plurality of traffics at a single transmission opportunity without departing from the range.

An apparatus for processing a frame in a wireless LAN according to an aspect of the present invention for achieving the above object is, when the LLC Logical Link Control Protocol Data Unit (PDU) is received from a higher layer, the frame waiting to be transmitted is stored The MAC processor generates a merge frame by merging the frame, the payload field of the received LLC PDU, and adds a Physical Layer Convergence Procedure (PLCP) preamble and a PLCP header to the received LLC PDU. When generating and acquiring a frame transmission opportunity according to IEEE 802.11, a PLCP processing unit for transmitting the PLCP frame through the wireless medium, and a queue for temporarily storing the PLCP frame generated by the PLCP processing unit.

When the LLC PDU is received from a higher layer, the MAC processing unit determines whether a frame is stored in the queue, and as a result of the determination, as a result of the determination, if the frame is stored in the queue, A merge determination unit that determines whether the stored frames and the received LLC PDUs can be merged; and when it is determined that the frames and the LLC PDUs can be merged according to the determination result of the merge determination unit, A merge processing unit for merging payload fields of the LLC PDU to generate a merge frame, a header setting unit for resetting a predetermined field value of a header of the merge frame generated by the merge processing unit, and temporarily storing the merge field in the queue, and the merge determination unit in a queue. If it is determined that the frame is not stored, it encapsulates the MAC header in the received LLC PDU and stores it temporarily in the queue. And a processing unit.

In addition, the PLCP processing unit according to the present invention, when the MAC processing unit acquires a frame transmission opportunity while generating the merge frame, the control unit provides a control signal to hold the job of generating the merge frame, the queue It is characterized by transmitting a frame having a transmission first rank among the frames temporarily stored in the.

On the other hand, the method for processing a frame in a wireless LAN according to another aspect of the present invention, when the LLC PDU is received from a higher layer, determining whether the frame is stored in the queue (Queue), the determination result, the queue If the frame is not stored in the encapsulation MAC header (Header) to the received LLC PDU, and temporarily stored in the queue, and as a result of the determination, if the frame is stored in the queue, Determining whether the stored frame and the received LLC PDU can be merged; and when the determination result, the stored frame and the received LLC PDU are mergeable, performing a merge operation to generate a merge frame. And resetting the header of the generated merge frame to temporarily store the queue in a queue, and when obtaining a frame transmission opportunity according to IEEE 802.11, the frame temporarily stored in the queue through a medium. And a step of transmitting.

The determining of whether the frame and the LLC PDU can be merged according to the present invention may include: identifying a message used to transmit the frame and a component of the message used to transmit the LLC PDU; Determining whether the components of each message are identical or not, and if the component of each message is not the same, determining that the frame and the LLC PDU cannot be merged. If the same, the merge payload value, which is the sum of the payload field value of the frame, the boundary value of the payload field, and the payload field value of the LLC PDU, and the boundary value of the payload field, is less than a predetermined bit value. And determining that the merge payload value is larger than the predetermined bit value, the frame and the LLC PDU cannot be merged. End result, if the combined payload value is less than the predetermined bit value, characterized in that it comprises the step of determining that the frame and the LLC PDU to merge possible.

Hereinafter, a method and a device for processing a frame in a WLAN according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a view for explaining each hierarchical structure of IEEE 802.11 applied to the present invention.

FIG. 1 illustrates a hierarchical structure applied to IEEE 802.11. The hierarchical structure of IEEE 802.2 can be easily divided into a data link layer and a physical layer, and the data link layer is a MAC (Media). The access layer may be divided into an access control layer and a logical link control (LLC) layer, and the physical layer may be divided into a physical layer convergence procedure (PCLP) layer and a physical medium dependent (PMD) layer.

The physical layer may correspond to Layer 1, which is the lowest layer of the OSI, and the MAC layer and the LLC layer, which is higher, may correspond to Layer 2.

Each layer having such a structure exchanges messages between layers adjacent to each other, thereby making it possible to use a service provided by a lower layer among the two layers.

First, the message exchange between the MAC layer and the LLC layer, the following three messages provided by the MAC layer is used.

First, the 'MA-UNITDATA.request' message serves to deliver a local service entity unit (MSDU) to a local LLC entity to one or more peer LLC entities.

The parameter of the 'MA-UNITDATA.request' message has the following structure.

MA-UNITDATA.request (

                     source address,

                     destination address,

                     routing information,

                     data,

                     priority,

                     service class

                     )

The 'Source Address' (SA) is the address of the MAC sub-layer object to which the MSDU is delivered, and the individual address of the 'Destination Address' (DA) MAC sub-layer object or the MAC sub-layer object. Group address.

'Routing information' is a transmission path of a frame to be transmitted, and has a null value in IEEE 802.11.

'Data parameter' indicates an MSDU to be transmitted by the MAC sublayer.

In addition, the 'Priority parameter' indicates a priority to be applied to the frame when transmitting the frame. In IEEE 802.11, only two values, 'Contention' or 'Contention Free' are used.

'Service class parameter' is a service class required when transmitting a frame, and has only two values of 'ReorderableMulticast' or 'StrictlyOrdered' in IEEE 802.11.

Secondly, the 'MA-UNITDATA.indication' message functions to send an MSDU from a MAC sublayer entity to one or more LLC sublayer entities.

The component of this 'MA-UNITDATA.indication' message has the following structure.

MA-UNITDATA.indication (

                        source address,

                        destination address,

                        routing information,

                        data,

                        reception status,

                        priority,

                        service class

                        )

'Source address' is the address specified in the 'Source address field' of the received frame, and 'Destination address' is the individual address or MAC of the MAC sub-layer object specified in the 'Destination address field' of the received frame. Group address of the sub-layer entity.

In addition, 'Routing information' indicates a transmission path used when transmitting data, and always has a null value in IEEE 802.11.

'Data parameter' specifies the MSDU received by the Local MAC entity.

In addition, the 'Reception status parameter' indicates whether the reception of the frame was successful or failed.

In addition, 'Priority parameter' indicates a priority used when transmitting data, and in IEEE 802.11, may have only two values, 'Contention' or 'Contention Free'.

'Service class parameter' indicates a receive service class used when transmitting data, and in IEEE 802.11, may have only two values of 'ReorderableMulticast' or 'StrictlyOrdered'.

Third, the 'MA-UNITDATA-STATUS.indication' message provides the LLC sub-layer with the status information of the previously generated 'MA-UNITDATA.request primitive'.

The component of this 'MA-UNITDATA-STATUS.indication' message has the following structure.

MA-UNITDATA-STATUS.indication (

                               source address,

                               destination address,

                               transmission status,

                               provided priority,

                               provided service class

                               )

'Source address' indicates the address of the MAC sublayer object specified in the corresponding 'MA-UNITDATA.request' message, and 'Destination address' indicates the MAC sublayer specified in the corresponding 'MA-UNITDATA.request' message. Represents an individual or group address of an object.

The 'transmission status parameter' provides status information to the local LLC entity, and the 'provided priority parameter' indicates a priority used when transmitting data.

In addition, 'Provided service class parameter' indicates a service class used when transmitting data.

2 is a flowchart illustrating a message exchange between MAC, PLCP, and PMD when transmitting a frame based on IEEE 802.11 to which the present invention is applied.

In order to start the transmission of the PLCP Protocol Data Unit (PPDU) from the MAC, the transmission start is allowed according to the MACS Carrier Sense Multiple Access / Collision Avoidance (CSMA / CA) method. admission).

In this case, physical collision sensing depends on the 'PHY-CCA.indicate message provided from the physical (PHY) layer to the MAC layer, and logical collision sensing is performed by the MAC. It takes care of itself.

When the channel for transmitting data is in the 'Clear' state, the Mac first generates a 'PHY-TXSTART.request (TXVECTOR)' message and transmits the message to the PHY PLCP.

The 'TXVECTOR' message is a 'Parameter List' that includes a number of elements, and the elements belonging to it are 'SIGNAL (DATARATE)', 'SERVICE', 'LENGTH' and PLCP header information. Information such as 'TX_ANTENNA' and 'TXPWR_LEVEL' which are required for PHY PMD.

Also, based on the information included in 'PHY-TXSTART.request (TXVECTOR)', PHY PLCP sets up antenna, transmission rate, RF output size, etc. necessary for data transmission, and sends 'PMD_TXSTART.request' message. Create and send to PHY PMD.

By this 'PMD_TXSTART.request' message, the PHY PMD starts to scramble and begin to transmit a 'PLCP Preamble'.

When the transmission of the 'PLCP Preamble' is completed, data transmission starts from the MAC to the physical layer by the successive exchange of 'PHY-DATA.request (DATA)' and 'PHY-DATA.confirm'. .

Data transmission between PHY PLCP and PHY PMD is done by 'PMD_DATA.request' message, and frame transmission generates 'PHY-TXEND.request' message in MAC or 'LENGTH Field' of 'PLCP Header' Data transmission ends when the transmission of all bits of the MPDU is completed according to the information.

3 is a block diagram illustrating a configuration of an apparatus for processing a frame in a wireless LAN according to a preferred embodiment of the present invention.

Referring to FIG. 3, the frame processing apparatus 20 according to the present invention includes a central processing unit 21, a queue 22, and a wireless interface unit 23, and the central processing unit 21 includes a pulse processing unit 21a. ) And the PLCP processing unit 21b.

The host 10 is a device capable of receiving a wireless LAN service provided by the frame processing apparatus 20, and the host processor 11 is a central processing unit of such a host.

That is, the host 10 is an upper layer of the MAC layer and exchanges a frame with the frame processing apparatus 20 to receive a wireless LAN service.

The queue 22 temporarily stores frames received from the host 10 for transmission over the wireless medium. That is, the queue 22 temporarily stores until the frame of the MAC layer is transmitted to the physical layer.

The air interface unit 23 interfaces for transmitting the frames temporarily stored in the queue 22 via the wireless medium. That is, it functions as a sub-layer of the Physical Medium Dependent (PMD), a modulator / transformer, a frequency converter, and a radio frequency (RF) circuit for transmitting / receiving a frame. ) May be included.

When the frame is received from the host 10, the CPU 21 temporarily stores the frame in the queue 22 and transmits the frame through the wireless medium.

The PLCP processing unit 21b of the central processing unit 21 performs a physical-layer convertgence procedure to transmit a frame received from the host 10 through a wireless medium. That is, the PLCP preamble and the PLCP header are added to transmit the frame received from the host 10 through the physical layer, and transmitted through the air interface unit 23.

The MAC processing unit 21a of the central processing unit 21 processes the MAC protocol, and exchanges frames with the host 10.

4 is a flowchart illustrating a method of processing data received by a Mac processor according to an exemplary embodiment of the present invention.

First, the MAC processor 21a receives an LLC protocol data unit (PDU) from the host 10 corresponding to the upper layer LLC layer (S 1).

That is, when the 'MA-UNITDATA.request' message is received from the host 10, the MAC processing unit 21a checks whether there is a frame that is temporarily stored in the queue 22 and waiting for transmission (S 2).

As a result of the check, when there is no frame temporarily stored in the queue 22, the MAC processing unit 21a encapsulates the LLC PDU received from the host 10 (S3).

5 is a view for explaining that the pulse processing unit applied to the present invention performs the insulation process.

As shown in FIG. 5, in order to transmit a frame from a MAC to a PHY, the MPDU is converted into a PLCP preamble including a 'SYNC' field and a 'SFD' field, and a 'SIGNAL' field and a 'SERVICE' field. It should be encapsulated with a PLCP header consisting of a field, a 'LENGTH' field and a 'CRC' field.
At this time, the 'SYNC' field is a field for synchronizing the bit timer between the sender / receiver, and the 'SFD' field is a field indicating the start of the actual data and the synchronization is terminated by a start of frame delimiter.

delete

Then, the Mac processor 21a temporarily stores the encapsulated frame in the queue 22 (S4).

On the other hand, when there is a frame temporarily stored in the queue 22, the MAC processing unit 21a determines whether the frame temporarily stored and the newly received LLC PDU can be merged (S5). If a plurality of frames are temporarily stored in the queue 22, the MAC processing unit 21a first determines whether the frames can be merged with the newly received LLC PDUs sequentially from a frame having a high transmission rank.

FIG. 6 is a flowchart illustrating a method of determining whether a MAC processor, which is applied to the present invention, may temporarily merge a frame temporarily stored in a queue and a newly received LLC PDU.

Referring to FIG. 6, the MAC processor 21a receives a 'MA-UNITDATA.request' message used to transmit an LLC PDU from a host 10, which is a higher layer (S 5a).

Then, whether the parameters of the received 'MA-UNITDATA.request' message and the 'MA-UNITDATA.request' message used to transmit the LLC PDU stored temporarily in the queue 22 are the same. It is determined whether or not (S 5b).

At this time, the MAC processor 21a determines whether the 'MA-UNITDATA.request' message components used to transmit each LLC PDU are the same as the 'source address' of each 'MA- UNITDATA.request' message. It determines whether the elements of 'destination address', 'routing information', 'priority' and 'service class' are the same.

As a result of the determination, when the elements of the message 'MA-UNITDATA.request' are not the same, it is determined that merging is impossible (S 5c).

On the other hand, if it is determined that the components of each 'MA-UNITDATA.request' message are the same, the MAC processing unit 21a size of the payload field of the frame temporarily stored in the queue 22. The size of each newly received LLC PDU is determined, and it is determined whether the sum of the size of each MSDU plus 15 bits is smaller than 2304 bytes (S 5d).

In this case, adding the '15' bit value to the size value of each MSDU is to indicate the size of each merged MSDU when one or more MSDUs are merged.

The determination of whether the sum of the values of the MSDUs plus the '15' bit value is smaller than the '2304' bytes is to determine whether one or more MSDUs can be merged and transmitted in one frame.

As a result, if the sum of the values of the MSDU plus 15 bits is greater than 2304 bytes, it is determined that the frame temporarily stored in the queue and the newly received LLC PDU cannot be merged (S 5c). ).

On the other hand, if the sum of the values of each MSDU plus 15 bits is smaller than 2304 bytes, the frame temporarily stored in the queue 22 and the newly received LLC PDU are merged in IEEE 802.11. Since it does not violate the defined one frame agreement, it is determined that the merge is possible (S 5e).

In addition, the MAC processor 21a determines whether the frame temporarily stored in the queue 22 and the newly received LLC PDU can be merged, and if it is determined that the frames cannot be merged (S 5c), the newly received frame is determined. Encapsulation is performed on the LLC PDU (S 3), and temporarily stored in the queue 22 (S 4).

On the other hand, if it is determined that the temporarily stored frame and the newly received LLC PDU can be merged, the corresponding frames are merged (S6). When a plurality of frames are stored in the queue 22, the MAC processing unit 21a may determine whether or not the frames can be merged with a newly received LLC PDU from a frame having a high transmission rank.

FIG. 7 is a flowchart illustrating a flow of a method in which a mac processor merges one or more frames according to a preferred embodiment of the present invention.

Referring to FIG. 7, if it is determined that a frame temporarily stored in the queue 22 and a newly received LLC PDU can be merged with each other, the MAC processing unit 21a temporarily stores the last element (that is, temporarily stored in the queue 22). last element) is copied (S10). The mac processor 21a copies the last element of the frame determined to be mergeable.

At this time, the element to be copied is a frame temporarily stored in the queue 22 without the FCS field.

The MAC processor 21a stores the copied last element in a new element (S 11), calculates a bit value of the new LLC PDU received from the upper layer, and stores it as a new_size variable ( S 12).

The bit value of the payload field of the new element is calculated and stored as an old_size variable (S 13).

In addition, a '15' bit field specifying the length of the MSDU is added to the front of the payload field of the new element, and the '15' bit value is added to the old_size variable and stored (S 14).

At this time, the MAC processing unit 21a determines whether the last element temporarily stored in the queue 22 is a frame that has already been merged and generated. Since the '15' bit field specifying the length has been added, the '15' bit value is not added to the old_size variable.

In addition, a '15' bit field indicating a size of the newly received LLC PDU is added to the end of the payload field of the new element, and the '15' bit value is added to the new_size variable and stored (S15).

The value stored as the new_size variable is allocated to the '15' bit field located behind the payload field of the new element, and the payload field of the last element and the newly received LLS PDU are merged (S16).

In addition, the persistent / ID field value of the new element is set, and the floating field value is reset (S17).

That is, since the new element is a frame generated by merging one or more MCUs, the persistent / ID field and the floating field value are set and specified.

Then, the last element temporarily stored in the queue 22 is replaced with the merged new element (S18).

8 is a view for explaining the structure of a merge frame according to an embodiment of the present invention.

Referring to FIG. 8, an IEEE 802.11 frame (a) includes a frame control field, a duration / ID field, a plurality of address fields, a payload field, and sequence control. ) Field and frame check sequence (FCS).

As shown in the figure, the payload fields (b) of the merged and generated frame add '15' bits before the MAC service data unit (MSDU) # 1, and then add '15' bits before the MSDU # 2. Add and merge.

Subsequently, a '15' bit may be added before the next MSDU #N to merge.

In this case, a '15' bit added before each MSDU is a bit field indicating the length of the corresponding MSDU. That is, when merging each MSDU, since the receiver cannot know the start and end of one MSDU, the '15' bit indicating the length of the MSDU is added before each MSDU to indicate the start and end of the MSDU. It is preferable.

9 is a view for explaining the structure of a frame control field applied to the present invention.

Referring to FIG. 9, the frame control field of a frame conforming to the IEEE 802.11 may include a protocol version field, a type field, a sub type field, a to DS field, a from DS field, and an additional fragment (more). frag field, retry field, power management field (PwrMgt) field, more data field, web (WEP) field, and order.

For a brief discussion of each field below, the protocol version field indicates the 802.11 Mac version that the frame is using, and the type and float fields indicate the type of frame that the frame is using.

The To DS and From DS fields indicate the purpose in the distributed system of the corresponding frame, and the additional fragment field indicates whether the corresponding frame is fragmented.

In addition, the retry field indicates whether the corresponding frame is retransmitted, the power management field is used to increase the battery life of the 802.11 adapter, the additional data field to the station operating in the power save mode (power save mode) A field used for providing reception information, a WEP field is a field for providing an encryption function in 802.11, and an order field is a field for providing an order in exchange for an additional operation by the transmitting / receiving side.

Among these frame control fields, the MAC processor 21a should set the type / subtype field to indicate that the corresponding frame includes one or more MSDUs due to merging.

Table 2 below describes an example of setting a type / type field value when one or more MSDUs are merged frames according to the present invention.

Type field value b3, b2 Type Field Value Description Floating field values b7, b6, b5, b4 Float Field Value Description 1 0 Data frames 1 1 1 1 Merged frame

As described in Table 2, by setting a type / type field value included in a frame control field of a merged and generated frame, a frame to be transmitted may specify a frame generated by merging one or more MSDUs.

Meanwhile, the case where the frame processing apparatus 20 acquires a transmission opportunity while the MAC processor 21a merges one or more MSDUs will be described.

First, when the frame to be merged is temporarily stored in the queue 22 to become the transmission priority 1, the Mac processing unit 21a merges the frame temporarily stored at the front of the queue 22 and has the transmission priority 1. When the frame processing apparatus 20 acquires a frame transmission opportunity while performing the operation, the MAC processing unit 21a terminates the merging operation during execution.

Then, the frames temporarily stored in the queue 22 and having the first transmission priority are first transmitted to the wireless medium through the air interface unit 23, and the encapsulated LLC PDUs being merged are encapsulated and queued to the queue 22. Save temporarily.

On the other hand, if the frame to be merged is temporarily stored in the queue 22, but not in the transmission first rank, that is, the MAC processing unit 21a holds the merge operation being performed and the head of the queue 22 is stored. A frame having a priority of transmission 1, which is temporarily stored in the front part, is first transmitted to the wireless medium through the air interface unit 23.

When the transmission of the frame having transmission 1 rank is completed, the held frame merging operation is performed.

In addition, when the MAC processing unit 21a completes the merge operation between the frame temporarily stored in the queue 22 and the newly received LLC PDU, the frame processing apparatus 20 transmits the frame due to contention by DCF (distributed coordination). When a transmission opportunity is acquired according to a point coordination function (PCF) method of transmitting a frame by a function method or polling, a merge frame temporarily stored in the queue 22 is transmitted.

Then, the MAC processing unit 21a of the receiving side frame processing apparatus 20 analyzes the header of the received frame to determine whether the corresponding frame is a merged frame.

At this time, the receiving side MAC processing unit 21a may determine whether the merged frame by analyzing the value of the type / sub-type field in the frame control field in the header of the received frame.

As a result, when the received frame is a merged frame, the MAC processor 21a analyzes the first '15' bit value of the payload field of the received frame to determine the length of the first MSDU.

The MS determines the first MSDU as many bits as the identified length, and then analyzes the '15' bit value to determine the length of the next MSDU.

In this way, the receiving MAC processor 21a analyzes the '15' bit in front of the MSDU included in the received merged frame, and identifies the boundary of the MSDU through the analyzed '15' bit value. Can be restored as a separate object

Although the present invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made within the technical spirit of the present invention, and such modifications and modifications belong to the appended claims. .

As described above, according to the present invention, if a wireless LAN terminal generates and temporarily stores one IEEE 802.11 frame by merging a plurality of MSDUs, and the wireless LAN terminal acquires a transmission opportunity for transmitting a frame, By transmitting IEEE 802.11 frames incorporating MSDUs, there is an effect of minimizing delays that occur until the MSDUs are temporarily stored in a queue and transmitted.

In addition, by transmitting fewer IEEE 802.11 frames than the number of MSDUs to be transmitted through the wireless medium, there is an effect of reducing the overhead generated in the WLAN system and increasing the efficiency of using the bandwidth.

In addition, since the number of times that a WLAN terminal wishing to transmit a frame through a wireless medium may participate in a competition to obtain a frame transmission opportunity may be reduced, the number of collisions that may occur in the wireless medium may be reduced, thereby increasing bandwidth utilization efficiency. Let's do it.

Claims (15)

In the apparatus for processing a frame in a wireless LAN, When a LLC Logical Link Control Protocol Data Unit (PDU) is received from a Logical Link Layer (LLC) layer, when a frame waiting to be transmitted is stored, the frame and the received LLC PDU are merged to merge a merge frame. Mac processing unit for generating a; A PLCP frame is generated by adding a PLCP (Physical Layer Convergence Procedure) preamble and a PLCP header to the received LLC PDU, and obtaining a frame transmission opportunity according to IEEE 802.11, and transmitting the PLCP frame to the PMD physical layer. Processing unit; And a queue for temporarily storing the MAC frame generated by the MAC processing unit. The method of claim 1, wherein the pulse processing unit, When the LLC PDU is received from the LLC layer, it is determined whether a frame is stored in the queue. As a result of the determination, when the frame is stored in the queue, the frame stored in the queue and the received LLC PDU are determined. A merge determination unit that determines whether or not merge can be performed; A merge processing unit for generating a merge frame by merging the payload field of the frame and the payload field of the LLC PDU when it is determined that the frame and the LLC PDU can be merged according to the determination result of the merge determination unit; A header setting unit for resetting a predetermined field value of a header of a merge frame generated by the merge processing unit and temporarily storing the predetermined field value in the queue; When the merging determination unit determines that no frame is stored in the queue, the merge determination unit includes an encapsulation processing unit for encapsulating a MAC header in the received LLC PDU and temporarily storing the MAC header in the queue. Device for processing frames in wifi. The method of claim 2, wherein the merging determination unit, A radio that determines whether the frame and the LLC PDU can be merged by determining whether a message transmitted for transmitting the frame from the LLC layer and a message used for transmitting the LLC PDU are identical. Device for processing frames in a LAN. The method of claim 2, wherein the merge processing unit, Copy each field value of the frame, add a predetermined field value indicating the payload field size of the frame and store it as a first variable, read the LLC PDU field value, and read the predetermined field value indicating the LLC PDU field size. Add, store the second variable, merge the second variable with the first variable, and generate a merge frame. The method of claim 4, wherein the merge processing unit, If the frame is a merged frame in which at least one payload field is merged, copy each field value of the merged frame and store it as a first variable, read the LLC PDU field value, and indicate a corresponding payload field size. Apparatus for processing a frame in a WLAN to add a field value, store as a second variable, and then merge the second variable to the first variable to generate a merged frame. The method of claim 2, wherein the predetermined field to be reset in the header setting unit, The apparatus for processing a frame in a wireless LAN, which is at least one of a type field and a sub-type field of the generated merged frame. The method of claim 1, wherein the pulse processing unit, When the MAC processor acquires a frame transmission opportunity while generating the merge frame, the MAC processor holds a job of generating the merge frame, and ranks transmission 1 among temporary frames stored in the queue. Device for processing frames in WiFi to transmit frames. In the method of processing a frame in a wireless LAN, When an LLC PDU is received from an upper LLC layer, determining whether a frame is stored in a queue; If the frame is not stored in the queue as a result of the determination, encapsulating a MAC header in the received LLC PDU, and temporarily storing the MAC header in the queue; Determining that the frames stored in the queue and the received LLC PDU can be merged when the frames are stored in the queue as a result of the determination; Generating a merge frame by performing a merge operation when the stored frame and the received LLC PDU can be merged as a result of the determination; And Resetting a header of the generated merge frame and temporarily storing the header in the queue; If a frame transmission opportunity is acquired according to IEEE 802.11, transmitting the frame temporarily stored in the queue via a medium. The method of claim 8, wherein the determining of whether the frame and the LLC PDU can be merged comprises: Identifying the message used to transmit the frame and the components of the message used to transmit the LLC PDU; Determining whether the elements of the identified messages are identical and determining that the frame and the LLC PDU cannot be merged when the components of the messages are not identical; As a result of the determination, when the components of the respective messages are the same, the size value of the payload field of the frame, the boundary value of the corresponding payload field, the field value of the LLC PDU, and the boundary value of the corresponding payload field Determining whether a merge payload size value that is a sum of less than a predetermined bit value is determined; As a result of the determination, if the size value of the merge payload is larger than the predetermined bit value, it is determined that the frame and the LLC PDU cannot be merged. As a result of the determination, the size value of the merge payload is larger than the predetermined bit value. If small, determining that the frame and the LLC PDU are mergeable. The method of claim 9, wherein the predetermined bit value, A method of processing a frame in a WLAN that is a payload field value of one IEEE 802.11 frame. 10. The method of claim 9, wherein the boundary value of the payload field, And a frame allocated adjacent to each merged LLC PDU to indicate a size of the LLC PDU. The method of claim 8, wherein the merging operation of the frame and the LLC PDU is performed by: In the WLAN for copying each field of the frame stored in the queue, merging the LLC PDU to the copied field to generate a merge frame, and replace the stored frame in the queue How to process frames. The method of claim 8, wherein resetting the header of the merge frame, Processing a frame in a WLAN by resetting a predetermined field value of the generated merge frame header so that a receiving side receiving the merge frame can recognize that at least one MSDU is included in a payload field of the merge frame. Way. The method of claim 13, wherein the predetermined field value, And a field value of at least one of a type field value and a sub-type field value of the merge frame header. The method of claim 8, wherein the transmission of the frame, When a frame transmission opportunity is acquired during the merging of the frame and the LLC PDU, the merging operation is held, and a frame having a transmission first priority among the frames temporarily stored in the queue is preferentially transmitted through a medium. How to process frames in wifi.

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