KR20080096349A - System and method to improve symmetry in data transfer in llc layer of peer to peer nfc device - Google Patents

Abstract

A system and a method for improving symmetry of data transfer in an LLC layer of a peer to peer NFC(Near Field Communication) device are provided to reduce an unnecessary time and improve a data transmission rate by removing a waiting time and a suspension period. An initiator periodically transmits an SYMM frame to a target(110). If an LLC(Logical Link Control) layer does not include additional data frames, the target sets 4 bits included in a control field of the LLC UI(Unnumbered Information) frame to 0 and transmits the set bit to the initiator(120). The initiator receiving the UI frame from the target transmits the SYMM frame to the target(130). If the LLC layer includes one or more data frames of an application level, the target sets 4 bits included in the control field of the LLC UI frame to 1 and transmits the set bit to the initiator(140). The initiator transmits the SYMM frame without the waiting of the suspension period(150).

Description

METHOD AND METHOD TO IMPROVE SYMMETRY IN DATA TRANSFER IN LLC LAYER OF PEER TO PEER NFC DEVICE

The present invention relates to a method for transmitting and receiving data in short-range wireless communication, and more particularly, to a method for increasing data throughput.

Near Field Communication (NFC) is used for communication with devices located within a distance of 10 cm. In the near field communication protocol stack, the NFCIP-1 standard is used on the physical layer of ISO 14443. In NFCIP-1, devices used for short-range wireless communication can be operated in an active mode and a passive mode, a short-range wireless communication device in a transmission mode is referred to as an initiator, and a short-range wireless communication device in a reception mode is referred to as a target.

In the passive mode, the NFCIP-1 device does not have the power required to modulate the RF field it generates, and thus cannot generate a request message on its own. Communication can always be initiated only by an initiator. That is, when the initiator in the active mode transmits the request message through the RF field, the target in the passive mode is supplied with power through the RF field to drive the receiving circuit. If the initiator does not have data to transmit, the SYMM frame is transmitted periodically. The target is a response to an SYMM frame or an information frame, and inserts its data into a frame received from an initiator and transmits the data. Thus, throughput (i.e. data rate) for data transmitted from a target depends on the frequency of the I frame or SYMM frame received from the initiator.

Furthermore, in the current LLCP version, the initiator has to wait for the reception of the response frame after transmitting the request frame. Due to the reception of such a response frame, data transmission may be delayed by a response wait time (RWT). In this mechanism, unidirectional data transmission from the target is inevitably dependent on the frequency used to transmit the SYMM frame from the initiator to the target.

As a result, when data to be transmitted between NFC devices increases, a problem arises in that the data transmission rate between devices performing near field communication decreases due to unnecessary idle periods or standby periods.

In order to solve this problem, there is a need for a fundamental method that can increase the data rate between devices performing short-range wireless communication.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described point, and an object thereof is to provide a method for reducing unnecessary waiting time occurring when data is transmitted and received between short-range wireless communication devices.

In order to achieve the above object, a data transmission / reception method according to the present invention is a LLC information frame (hereinafter referred to as LLCP) layer of a peer-to-peer (NFC) near field communication (NFC) device. , I frame) is set to '0' or '1' and used as an additional data bit identifier.

When the target / initiator device transmits at least one data frame to the counterpart target / initiator device, the additional data bit is set.

At the receiving end of the I frame, if the bit is set and there is no frame transmitted by the receiver, it checks whether an additional data bit is set, and the device immediately goes without waiting time until the end of the sleep timer (SYMM timer). It is preferable to transmit the SYMM frame.

Before sending the first SYMM frame to the target, the initiator may start a sleep timer (SYMM timer) and wait for the end of the timer.

The initiator receives from the target a first response frame in which the specific bit is set to '0', and initiates an operation of the SYMM timer for SYMM frame transmission.

According to another aspect of the present invention, there is provided a method for transmitting and receiving near field communication (NFC), comprising: (a) an initiator transmitting a data frame to a target; and (b) a target from an initiator. As a response to the transmitted data frame, setting a specific bit of the LLC information frame to '0' or '1' and transmitting the same; and (c) the initiator identifies the specific bit of the response frame and correspondingly Waiting for a predetermined time or transmitting the next data bit to be transmitted without waiting.

The LLC information frame includes an information frame (I) and an unnumbered information frame (UI).

Preferably, the specific bit may be the fourth bit of the control field.

If the specific bit is set to '0' in step (b), the next frame is transmitted after waiting for a predetermined waiting time in step (c), and if the specific bit is set to '1', then (c) ), The next frame is sent immediately without waiting for the predetermined waiting time.

Preferably, the LLC information frame may be a response frame to the SYMM frame.

In the transmission and reception of data frames between short range wireless communication devices, unnecessary time can be reduced and data transmission rate can be increased by eliminating waiting time and idle periods.

In addition, the initiator can communicate with the target while scheduling transmission of the SYMM frame without waiting or idle periods, thereby improving the balance on data transmission at the LLC layer of the P2P NFC device.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, specific details such as specific components are shown, which are provided to help a more general understanding of the present invention, and it is understood that these specific details may be changed or changed within the scope of the present invention. It is self-evident to those of ordinary knowledge in Esau.

Short-range wireless communication may be performed through data transmission and reception between the initiator and the target. The initiator periodically generates and emits an RF field containing the SYMM frame. When a target is moved into the RF field area, the target is driven with an RF signal from an initiator as a power source. The target load modulates the RF signal, thereby transmitting a response frame to the SYMM frame.

1 is an exemplary diagram of an I frame structure generated according to an embodiment of the present invention, and FIG. 2 is an exemplary diagram of a UI frame structure generated according to an embodiment of the present invention. 1 and 2, an I and UI frame according to an embodiment of the present invention includes a Destination Service Access Poin (DSAP) field 10 including an address of a destination, and a Source Service Access (SSAP) including an address of a destination. Poin) field 20, control field 30 and data information fields (40, 50).

The DSAP 10, the SSAP 20, and the control field 30 are provided with the same size and structure in the I and UI frames. On the other hand, the data information fields 40 and 50 are set differently in I and UI frames. In detail, the data information field 40 included in the I frame includes a field 43 for recording a plurality of data packet units and a field for recording the sequence number of the first data packet unit transmitted among the data packet units to be transmitted ( 42). In addition, the data information field 40 of the I frame may further include a field 41 that records the number of response sequences set corresponding to the number of sequences of the last data packet unit.

The response sequence number may be set corresponding to the data packet unit finally provided among the data packet units included in the payload included in the data information field 40. The response sequence number may be a value increased by one unit than the number of finally provided data packet units. For example, suppose that the data information field 40 of an I frame is provided with three data packet units integrated, and the field 42 containing the sequence number of the first data packet unit transmitted is set to four. The sequence number of three data packet units included in the data information field 40 is sequentially assigned based on the number of sequences of the first data packet unit transmitted. Accordingly, the number of sequences of the last data packet unit in the data information field 40 may be six. In addition, the field 41 including the number of response sequences may be set to 7, which is a unit increase from 6, which is the number of sequences of the final data packet unit.

Meanwhile, the data information field 50 of the UI frame illustrated in FIG. 2 does not have a field for recording a sequence included in an I frame, but includes a plurality of data packet units.

3 shows a structure of a control field according to an embodiment of the present invention. Referring to FIG. 3, the control field 30 provided in I and the UI frame in the same manner is provided in the size of 1 byte. Commands are stored in bits 0 to 3 of the second field 31.

 The present invention adds an identifier as to whether an additional data frame has been described in the transmission queue of the transmission device. Therefore, in the present embodiment, 4 bits 32 which are not defined separately in the LLCP specification are used to identify the presence or absence of additional data in the I or UI frame. Information contained in the four bits 32 may be defined as shown in Table 1 below.

Control value Directing Information 0 Additional data frame does not exist One Additional data frame present

'0' indicates that no additional data frame is described in the transmission queue of the transmission device, and '1' indicates that no additional data frame is described in the transmission queue of the transmission device.

On the other hand, the 5 bits and 6 bits 31 provided in the control field 30 contain information indicating the type of the frame. Information contained in 5 bits and 6 bits 31 may be defined as shown in Table 2 below.

Control value Directing Information 00 supervisory 01 Unnunbered I Frame 10 I frame 11 Other

In Table 1, '00' indicates supervisory signals used to indicate or change various operating states of circuit combinations, '01' indicates that the frame is a UI frame, and '10' indicates that the frame is an I frame. Instruct. In this way, it is possible to identify whether the data frame is an I or UI frame through the 5 bits and 6 bits 31 contained in the control field 30.

Hereinafter, a data transmission and reception method according to an embodiment of the present invention will be described by using a data frame according to an embodiment of the present invention having the above-described structure.

4 is a flowchart illustrating a procedure of a data transmission and reception method according to an embodiment of the present invention. Referring to FIG. 4, in the data transmission / reception method according to an embodiment of the present invention, an initiator periodically transmits a SYMM frame 110 to a target 110 and a UI as a response to the SYMM frame periodically received from the initiator. Return the frame. In this case, if the LLC layer does not include additional data frames, the target transmits the 4-bit included in the control field of the LLC UI frame to an initiator by setting it to '0' (120).

Next, the initiator receiving the UI frame from the target again transmits the SYMM frame to the target (130).

Preferably, the initiator operates the SYMM timer by checking that 4 bits of the control field included in the received UI frame are set to '0' before performing process 130, until the operation of the SYMM timer ends. The process may include waiting 125 for a predetermined idle period.

If the LLC layer includes one or more application level data frames, the target transmits the four bits included in the control field of the LLC UI frame to an initiator by setting it to '1' (140). Then, the initiator determines that 4 bits of the control field included in the received UI frame is set to '1', and immediately transmits the SYMM frame without waiting for a separate idle period (150).

In FIG. 1, steps 150, 160, 170, and 180 may be performed in a method corresponding to steps 130 and 140.

Furthermore, the parameter of whether to support the additional bit identification proposed in the present invention may be included in the negotiation of the initial parameter, and such a method may be variously applied by those skilled in the art. Of course.

In an embodiment of the present invention, it is illustrated that the target transmits whether or not to describe the additional data frame using 4 bits of the control field included in the UI frame as a response to the frame received from the initiator. However, the present invention is not limited to this. For example, although the target transmits whether the additional data frame is described to the initiator using the UI frame, an I frame may be adopted as an alternative thereto. In addition, although the target includes the additional bit identifier in the response frame to the SYMM frame from the initiator, the additional bit identifier may be transmitted in the I and UI frames transmitted by the initiator to the target. In addition, whether or not to describe an additional data frame is described using 4 bits of the control field, but other redundant bits may be used. In addition, the transmitting device including the additional bit identifier can be both an initiator and a target.

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto, and various modifications and changes may be made by those skilled in the art to which the present invention pertains.

1 is an exemplary diagram of an I frame structure generated according to an embodiment of the present invention.

2 is an exemplary diagram of a UI frame structure generated according to an embodiment of the present invention.

3 is an exemplary view of a control field structure according to an embodiment of the present invention.

4 is a flowchart illustrating a procedure of a data transmission / reception method according to an embodiment of the present invention.

Claims (12)

In the point-to-point (P2P) Peer to Peer (PLP) Logical Link Control Protocol (LLCP) layer of a near field communication (NFC) device, A method in which a particular bit of an LLC information frame (hereinafter referred to as an I frame) is set to '0' or '1' and used as an additional data bit identifier. 2. The method of claim 1, wherein the additional data bits are set when the target / initiator device transmits at least one data frame to a counterpart target / initiator device. The apparatus of claim 1, wherein, at the receiving end of the I frame, if the bit is set and there is no frame transmitted by the receiver, it is checked whether an additional data bit is set, and the device terminates a sleep timer (SYMM timer). A method for improving the balance of data transmission, characterized by the immediate transmission of SYMM frames without waiting time. 2. The method of claim 1, wherein the initiator starts a sleep timer (SYMM timer) and waits for the end of the timer before sending the first SYMM frame to the target. The method of claim 1, And the initiator receives from the target a first response frame in which the specific bit is set to '0', and initiates an operation of the SYMM timer for SYMM frame transmission. In a communication method between a first short range wireless communication device and a second short range wireless communication device performing Near Field Communication (NFC), (a) transmitting a data frame by the first short range wireless communication device to the second short range wireless communication device; (b) the second short-range wireless communication responding to the data frame transmitted from the first short-range wireless communication device, setting a specific bit of the LLC information frame to '0' or '1' and transmitting the same; (c) the first short-range wireless communication device identifying a specific bit of the response frame, and correspondingly waiting for a predetermined time or transmitting a data bit to be transmitted next without waiting time. How to send and receive. The method of claim 6, wherein the LLC information frame comprises an information frame (I) and an unnumbered information frame (UI). 7. The method of claim 6, wherein the specific bit is a fourth bit of a control field. The method according to any one of claims 6 to 8, wherein if the specific bit is set to '0' in step (b), the next frame is transmitted after waiting for a predetermined waiting time in step (c). , And if the specific bit is set to '1', in step (c), the next frame is transmitted immediately without waiting for a predetermined waiting time. The method according to any one of claims 6 to 8, The data frame of step (a) is a SYMM frame, And the LLC information frame of step (b) is a response frame to the SYMM frame. The method of claim 9, The data frame of step (a) is a SYMM frame, And the LLC information frame of step (b) is a response frame to the SYMM frame. The method of claim 9, The first short-range wireless communication device is a short-range wireless communication device that operates as an initiator, And the second short range wireless communication device is a short range wireless communication device operating as a target.

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