CN102932449B - The LLC sublayer condition control method of Dedicated Short Range Communications, and board units - Google Patents

Abstract

The present invention relates to a kind of LLC sublayer condition control method and board units of Dedicated Short Range Communications, of intelligent transportation field.Under nothing is connected with affirmation mode, when the order PDU that the LLC sublayer of roadside unit receives application layer in an idle state sends request, this order PDU is sent to board units by media access control sublayer, enter wait state subsequently, after receiving the correct response pdus of board units, get back to idle condition; When the LLC sublayer of board units receives the order PDU of roadside unit transmission in the ready state, according to the order PDU received, after selectivity carries out state transitions process from the various states transfer processing preset, get back to ready state.Wherein various state transitions situation is set in conjunction with specific event and action by standardized event and action, and the process of these state transitions is divided into: normal response process; Delayed response process; Exception response process; And retransmit response process.

Description

The LLC sublayer condition control method of Dedicated Short Range Communications, and board units

Technical field

The present invention relates to electric non-stop toll (the Electronic Toll Collection of intelligent transportation system, be called for short ETC) systems technology field, particularly relate to a kind of Dedicated Short Range Communications, (DSRC for ETC system, Dedicated Short RangeCommunications, be called for short DSRC) logic link control (LLC, Logic Link Control) the sublayer condition control method of agreement and board units.

Background technology

Along with highway mileage open to traffic constantly increases, the continuous progress of toll collection technique, a lot of provinces and cities of China have all built highway electric non-stop toll) system.Compared with manual toll collection mode, electric non-stop toll can improve speed greatly, reduces vehicle queue waiting time, alleviates traffic congestion situation and reduces toxic emission.

The core feature of ETC system (or claims roadside unit by the ETC antenna of charge station, Road Side Unit, be called for short RSU) and the vehicle that misses the stop on install vehicle carried electronic label (or title board units, On Board Unit, be called for short OBU) realize charging transaction by the mode of radio communication, communication protocol adopts dedicated short-range communication.

Dedicated Short Range Communications, is one of important basic communication protocol in intelligent transport system field, is widely used in road electric non-stop toll, Vehicular traffic information service, traffic information collection, and the field such as vehicle public safety service.In May, 2007, the serial Dedicated Short Range Communications, national standard of China issuing and implementation GB/T 20851, the electronic toll system and the product that meet this standard are afterwards widely used.

The traffic model of DSRC agreement forms primarily of application layer, data link layer and physical layer, wherein data link layer is mainly used in setting up between communication entity and communicates reliably, by medium access control (MAC, MediaAccess Control) sublayer and logic link control (LLC, Logic Link Control) sublayer composition.The major function of media access control sublayer comprises the encapsulation of Frame/remove stage makeup and costume, the addressing of frame and identification, the reception of frame and transmission, the management of link and the error control etc. of frame, LLC sublayer is then for generation of the bidding protocol data cell (PDU for transmitting, Protocol Data Unit) and response pdus, and explain the order PDU and response pdus that receive.

The DSRC standard existed in the world at present mainly contains Europe, the U.S., Japan and four kinds, China.The European standard committee (CEN) DSRC " the ENV 12795 data link layer " pre-standard of promulgating in 1997, the service primitive that should realize LLC sublayer and protocol procedures element have carried out some and have described, and with reference to " IEEE 802.2: logic link control (LLC) ", the state machine of DSRC LLC sublayer is described, but it describes and imperfection, the efficiency realized by it is also not fully up to expectations.For those reasons, CEN is when promulgating formal DSRC data link layer standard EN 12795 in 2004, the state machine eliminating LLC sublayer describes, thus makes received text more refining, clear, but the logic no longer realized LLC sublayer and function make Uniform provisions.Within 2007, China has promulgated electronic charging DSRC national standard, based on same reason, does not also explain to the specific implementation of LLC sublayer.In Chinese Industrial Standards (CIS), board units adopts two-piece type electronic tag, and be namely made up of vehicle carried electronic label and IC-card two parts, wherein IC-card service speed is lower.In this case, will inevitably occur such problem: roadside unit is given an order, need board units to respond, and include very complicated encryption and decryption operation in the process of now board units execution roadside unit order, response speed is slower.If according to European pre-standard or Nippon Standard, need regulation T3 ~ T3+T4a period in return response data, this be Chinese national standard low speed IC-card institute irrealizable.Therefore, the standard of other countries or pre-standard can not be applicable to the situation of China completely.Low speed data implementation is clearly given to this in the present invention.

Patent of invention CN101848233A proposes the logical link control method based on LLC sub layer of on board unit of Chinese standard ETC system, wherein have employed special logic to realize LLC sublayer according to Chinese national standard.But, there is such defect in CN101848233A: the logical link control method wherein proposed is only the LLC control of substate method of board units, and do not specify the LLC control of substate method of roadside unit, and imperfect therefore, and, this control method adopts special logic to realize, and comparatively simply, and is not suitable for carrying out comparatively complicated control.

Summary of the invention

For the problems referred to above of the prior art, the present invention is based on the design standard of other countries and the GB of China, the LLC sublayer logical link control method of above-mentioned two kinds of standards propose further supplementary and perfect, propose the board units LLC control of substate method of applicable CNS (being called for short " GB ") and the complete scheme of roadside unit LLC control of substate method, simultaneously, often there are for the board units response of China the actual conditions postponed in this control method, proposes effective solution.In addition, this control method not only can carry out Design and implementation by hardware (chip), and can be realized by software, can realize comparatively complicated controlling functions, and for minimizing somersault and power consumption significant.

The invention provides a kind of LLC sublayer condition control method of Dedicated Short Range Communications, of intelligent transportation field.It not only can adapt to the slower national conditions of the response speed of two-piece type electronic tag board units, and not only can carry out Design and implementation by hardware (chip) but also can have been realized by software, comparatively complicated controlling functions can be realized, and for minimizing somersault and power consumption significant.

The board units that the Dedicated Short Range Communications, that present invention also offers a kind of intelligent transportation field uses.The LLC sublayer of this board units is designed to, even if can not return the situation of response data in time, also this situation can be informed to roadside unit, and very fast when meeting with a response data response data is supplied to roadside unit.

According to an aspect of the present invention, a kind of LLC sublayer condition control method of the Dedicated Short Range Communications, for intelligent transportation field is provided.Wherein, connect without under affirmation mode in nothing, the LLC sublayer of roadside unit and board units receives the order PDU of the other side in the ready state during via MAC layer, this order PDU is transferred to application layer to be processed by application layer, and, when the order PDU receiving application layer sends request, send this order PDU by media access control sublayer.Under nothing is connected with affirmation mode, when the order PDU that the LLC sublayer of roadside unit receives application layer in an idle state sends request, this order PDU is sent to board units by media access control sublayer, enter wait state subsequently, after receiving the correct response pdus of board units, get back to idle condition; When the LLC sublayer of board units receives the order PDU of roadside unit transmission via media access control sublayer in the ready state, according to the order PDU received, after selectivity carries out state transitions process from the various states transfer processing preset, get back to ready state.Wherein, various state transitions situation is set in conjunction with specific event and action by standardized event and action, different response pdus is beamed back respectively to roadside unit, the process of these state transitions is divided into: normal response process, wherein, the LLC sublayer of board units can processing command PDU in time; Delayed response process, wherein, the LLC sublayer of board units can processing command PDU, but response speed is slower; Exception response process, wherein, the reception of order PDU is wrong, or the LLC sublayer of board units can not processing command PDU; And retransmit response process, wherein, order PDU is retransferring of a upper order be conveyed through, and, wherein, the LLC sublayer of described roadside unit is according to current residing state, the order PDU received from application layer and the response pdus received from board units, and process according to the various states transfer case preset, various state transitions situation is set in conjunction with specific event and action by standardized event and action.Wherein, described standardized event and action are event primitive and the primitive acts of regulation in DSRC GB GB/T 20851.2-2007.

According to a further aspect in the invention, a kind of board units of the Dedicated Short Range Communications, for intelligent transportation field is provided.This board units is divided into physical layer, data link layer and application layer, and data link layer comprises LLC sublayer and media access control sublayer, and wherein, LLC sublayer comprises: interface unit, for carrying out data transmission with media access control sublayer and application layer; Control unit, for the operation of control LLC sublayer; And buffer cell.Wherein, connect without under affirmation mode in nothing, under the control of the control unit, when the LLC sublayer of described board units receives the order PDU of roadside unit via interface unit from MAC layer in the ready state, via interface unit, this order PDU is transferred to application layer to be processed by application layer, further, when the order PDU receiving application layer via interface unit sends request, this order PDU is sent via interface unit by media access control sublayer.Under nothing is connected with affirmation mode, when the LLC sublayer of described board units receives the order PDU of roadside unit transmission via interface unit from media access control sublayer in the ready state, under the control of the control unit, according to the order PDU received, after selectivity carries out state transitions process from the various states transfer processing preset, get back to ready state; Wherein, various state transitions process is set in conjunction with specific event and action by standardized event and action, different response pdus is beamed back respectively to roadside unit, the process of these state transitions is divided into: normal response process, wherein, the LLC sublayer of board units can processing command PDU in time; Delayed response process, wherein, the LLC sublayer of board units can processing command PDU, but processing speed is slower; Exception response process, wherein, the reception of order PDU is wrong, or the LLC sublayer of board units can not processing command PDU; And retransmit response process, wherein, order PDU is retransferring of a upper order be conveyed through.Wherein, described standardized event and action are the event primitive and primitive acts that specify in DSRC GB GB/T 20851.2-2007.

According to above-mentioned LLC sublayer condition control method, or according to above-mentioned board units, wherein, the delayed response process of board units comprises following process: occurring event RECEIVE_ACn_CMD (SQC=V (RI), P=1, INFO<>NULL), RECEIVE_STATUS ()=OK and ACCESS () <>OK time, namely, when the order PDU received retransmits order, need to fetch data from board units, information field is not empty, the information field of order PDU receives successfully, and the order PDU response data of asking still unavailable time, take action DELETE_SAVE_BUFFER, REPLY_INDICATION (LSDU=INFO), with SEND_ACn_RSP (SQR=1-SQC, F=1, C=OK, R=NE, LSDU=NULL), namely the data stored in buffer cell are deleted in the LLC sublayer of board units, send the data in order PDU to application layer, data in the information field of response pdus are set to sky, and described responsive state designator is set to instruction response data not yet submit to, simultaneously, LLC sublayer waits for that application layer provides data.

And, wherein, the LLC sublayer of board units is after sending the data in order PDU to application layer, wait for that application layer provides data, until there is event REPLY_UPDATE_REQUEST, namely application layer notifies to LLC sublayer that the data of asking are ready and indicates LLC sublayer to store this data, action SAVE:=GIVEN_LSDU and REPLY_UPDATE_STATUS_INDICATION is taked in LLC sublayer after being notified, namely receive the data of asking and described data are stored in buffer cell, and notifying that application layer upgrades.

According to the complete control method that LLC sublayer of the present invention condition control method is a kind of applicable Chinese national standard, and it can tackle the actual conditions that China's board units often exists operating lag, and there will not be mistake.

Board units according to the present invention is the board units of existing regulation in a kind of applicable Chinese national standard, even if response data can not be returned in time, this situation also can be informed to roadside unit by time, and very fast when meeting with a response data response data is supplied to roadside unit.

Accompanying drawing explanation

Fig. 1 is the synoptic chart of board units and roadside unit communication system.

Fig. 2 is the structural representation of board units LLC sublayer.

Fig. 3 is the state transition diagram of LLC1 assembly.

Fig. 4 is the state transition diagram of LLC3 receiving unit.

Fig. 5 is the state transition diagram of LLC3 sending assembly.

Embodiment

The present invention makes based on the relevant regulations in DSRC GB GB/T 20851.2-2007, and therefore, the understanding of the present invention, can carry out with reference to GB/T 20851.2-2007.

See Fig. 1, the invention provides a kind of LLC sublayer condition control method of the Dedicated Short Range Communications, for intelligent transportation field.Here, the information exchange between board units OBU and roadside unit RSU, has two kinds of patterns: without connecting without affirmation mode (Class1); Affirmation mode (type 3) is connected with nothing.Class1 operating provision one has the nothing connection of minimal protocol complexity without the service of validation testing, that is, do not confirm when board units and roadside unit receive information.Class1 operational order is also called UI(unnumbered information) order.Type 3 operating provision nothing is connected with the data cell Exchange Service of validation testing, and it allows a website to ask again response while transmission data, that is, need to confirm when board units and roadside unit receive information.Type 3 operational order and response are also called ACn command and response.

According to this control method, connect without under affirmation mode in nothing, the LLC sublayer of roadside unit and board units receives the order PDU of the other side in the ready state during via MAC layer, this order PDU is transferred to application layer to be processed by application layer, and, when the order PDU receiving application layer sends request, send this order PDU by media access control sublayer.Under nothing is connected with affirmation mode, when the order PDU that the LLC sublayer of roadside unit receives application layer in an idle state sends request, this order PDU is sent to board units by media access control sublayer, enter wait state subsequently, after receiving the correct response pdus of board units, get back to idle condition; When the LLC sublayer of board units receives the order PDU of roadside unit transmission via media access control sublayer in the ready state, according to the order PDU received, after selectivity carries out state transitions process from the various states transfer processing preset, get back to ready state; Wherein, the various state transitions process of the LLC sublayer of described board units are set in conjunction with specific event and action by standardized event and action, different response pdus is beamed back respectively to roadside unit, the process of these state transitions is divided into: normal response process, wherein, the LLC sublayer of board units can processing command PDU in time; Delayed response process, wherein, the LLC sublayer of board units can processing command PDU, but processing speed is slower; Exception response process, wherein, the reception of order PDU is wrong, or the LLC sublayer of board units can not processing command PDU; And retransmit response process, wherein, order PDU is retransferring of a upper order be conveyed through, and, wherein, the LLC sublayer of described roadside unit is according to current residing state, the order PDU received from application layer and the response pdus received from board units, and be set with various states transfer case, various state transitions situation is set in conjunction with specific event and action by standardized event and action.

And, see Fig. 2, the invention provides a kind of board units of the Dedicated Short Range Communications, for intelligent transportation field, this board units is divided into physical layer, data link layer and application layer, data link layer comprises LLC sublayer and media access control sublayer, wherein, LLC sublayer comprises: interface unit, for carrying out data transmission with media access control sublayer and application layer; Control unit, for the operation of control LLC sublayer; And buffer cell.Wherein, connect without under affirmation mode in nothing, under the control of the control unit, when the LLC sublayer of described board units receives the order PDU of roadside unit via interface unit from MAC layer in the ready state, via interface unit, this order PDU is transferred to application layer to be processed by application layer, further, when the order PDU receiving application layer via interface unit sends request, this order PDU is sent via interface unit by media access control sublayer.And, under nothing is connected with affirmation mode, when the LLC sublayer of described board units receives the order PDU of roadside unit transmission via interface unit from media access control sublayer in the ready state, under the control of the control unit, according to the order PDU received, after selectivity carries out state transitions process from the various states transfer processing preset, get back to ready state.Wherein, various state transitions process is set in conjunction with specific event and action by standardized event and action, different response pdus is beamed back respectively to roadside unit, the process of these state transitions is divided into: normal response process, wherein, the LLC sublayer of board units can processing command PDU in time; Delayed response process, wherein, the LLC sublayer of board units can processing command PDU, but processing speed is slower; Exception response process, wherein, the reception of order PDU is wrong, or the LLC sublayer of board units can not processing command PDU; And retransmit response process, wherein, order PDU is retransferring of a upper order be conveyed through.

Below the structure of this control method and board units LLC sublayer is specifically described.

1, without connecting without affirmation mode (Class1)

Connect without under affirmation mode in nothing, the LLC sublayer of roadside unit and board units receives the order PDU of the other side in the ready state during via MAC layer, this order PDU is transferred to application layer to be processed by application layer, and, when the order PDU receiving application layer sends request, send this order PDU by media access control sublayer.

Specifically, owing to not confirming the information received without under affirmation mode without connecting, therefore comparatively simple without the control under affirmation mode without connection, its control method can be regarded as and undertaken by Class1 assembly (can be described as again " without connection without affirmation mode assembly "): this assembly is responsible for ordering according to the request transmission types 1 of application layer; Process the Class1 order received from media access control sublayer, and handed to application layer.

In LLC sublayer, Class1 assembly is responsible for send/receive all types 1LPDU(logical protocol data cell for certain particular link address).According to the request of LLC user, Class1 assembly sends UI order PDU(protocol Data Unit) to one (being present in upstream or downstream link) or multiple (being only present in down link) far-end SAP(service access unit), nationality is to transmit a service data unit.After receiving UI order PDU, far-end SAP is without the need to confirming.

The state-transition table of Class1 assembly is as shown in table 1, co-exists in two states transfer case.

Table 1: Class1 component states transfer table

READY(is ready) be the unique states of Class1 assembly.In this case, SAP can receive the order PDU with transmission types 1.The state transition diagram of this assembly as shown in Figure 2.

State transitions in upper table is described as follows:

State transitions 1: Class1 assembly receives an opposite end LSAP(Connection Service accessing points) the UI order of sending

PDU, and transferred to application layer.

State transitions 2: Class1 assembly receives application layer UI order and sends request, and send this order by media access control sublayer.

Event in upper table and action are event primitive and the primitive acts of regulation in DSRC GB GB/T 20851.2-2007, only provide schematic illustration here.Event description is as follows:

(1) RECEIVE_UI:MAC sublayer delivers a MA-DATA.indication primitive to LLC sublayer, wherein contains UI order PDU.

(2) UNITDATA_REQUEST: application layer delivers a DL-UNITDATA.request primitive to LLC sublayer.

Action description in upper table is as follows:

(1) UNITDATA_INDICATION: the DL-UNITDATA.indication primitive comprising LSDU to application layer transmission one, the content of this LSDU is equal to the UI order PDU information field corresponding with it received before this.

(2) TRANSMIT_UI: transmit the MA-DATA.request primitive that one comprises UI order PDU to media access control sublayer.At RSU end, response request (Response Request) parameter of DL-UNITDATA.request service primitive should by the RR Parameter transfer of F-MA-DATA.request service primitive to media access control sublayer.

2, without being connected with affirmation mode (type 3)

Under nothing is connected with affirmation mode, when the order PDU that the LLC sublayer of roadside unit receives application layer in an idle state sends request, this order PDU is sent to board units by media access control sublayer, enter wait state subsequently, after receiving the correct response pdus of board units, get back to idle condition; When the LLC sublayer of board units receives the order PDU of roadside unit transmission via media access control sublayer in the ready state, after carrying out certain state transitions process, get back to ready state.Wherein, the LLC sublayer of described board units is according to the order PDU received, be set with various states transfer case, various state transitions situation is set in conjunction with specific event and action by standardized event and action, the process of these state transitions is divided into: normal response process, wherein, the LLC sublayer of board units can respond to order PDU in time; Delayed response process, wherein, the LLC sublayer of board units can respond to order PDU, but response speed is slower; Exception response process, wherein, the reception of order PDU is wrong, or the LLC sublayer of board units can not processing command PDU; And retransmit response process, wherein, order PDU is retransferring of a upper order be conveyed through.And, wherein, the LLC sublayer of described roadside unit is according to current residing state, from the order PDU of application layer reception and the response pdus from board units reception, be set with various states transfer case, various state transitions situation is set in conjunction with specific event and action by standardized event and action.

The control method of type 3 can regard as by type 3 sending assembly and type 3 receiving unit (can be described as again " and without be connected with affirmation mode sending assembly and without being connected with affirmation mode receiving unit ") carry out.In ETC DSRC standard, in order to simplify the realization of system, usually according to the equipping rules of " master slave mode ", only allow RSU initiatively to send ACn order, the ACn order that OBU can only send according to RSU responds.We are called for short this pattern is " the DSRC pattern of simplification ".Like this, only present pattern 3 sending assembly in RSU, only present pattern 3 receiving unit in OBU.Therefore, type 3 sending assembly can be described as again " RSU assembly ", and type 3 receiving unit can be described as again " OBU assembly ".Type 3 receiving unit is responsible for processing the type 3 received from media access control sublayer orders, and the response of return type 3 is to the person of sending of this order.At RSU end, LLC is that each dedicated link address (each OBU in corresponding communication zone) provides independently type 3 receiving unit.At OBU end, LLC can only have type 3 receiving unit at synchronization.Type 3 sending assembly is responsible for ordering according to the request transmission type 3 of application layer, and the type 3 that process receives from media access control sublayer responds.At RSU end, LLC is that each dedicated link address (each OBU in corresponding communication zone) provides independently type 3 sending assembly.At OBU end, LLC can only have type 3 sending assembly at synchronization.

2.1 type 3 receiving units (OBU assembly)

Type 3 receiving unit is responsible for distally LLC and is received ACn order, and returns corresponding ACn and respond.Each dedicated link address of ordering PDU corresponding with received type 3 has type 3 receiving unit, and this assembly only has a kind of state, namely READY(is ready) state.LLC can type of receipt 3PDU in this condition, and confirms it.The state transition diagram of this assembly as shown in Figure 3.

LLC is when responding, and according to the regulation of DSRC GB, the necessary operation of each state transition process all will complete in certain time interval (link samsara time T3).

All state informations of assembly are included in state variable.During the state of the order PDU that the inspection of each receiving unit repeats or previous receipt, all use oneself receiving sequence state variable V (RI) and reception success or failure state variable V (RB).

At OBU end, have and only have type 3 receiving unit.

The LLC sublayer of board units is according to the order PDU received, be set with various states transfer case, various state transitions situation is set in conjunction with specific event and action by standardized event and action, and its process can be divided into: normal response process, delayed response process, exception response process and re-transmission response process.

2.1.1 normal response process

When board units LLC sublayer can in time processing command PDU, OBU assembly carries out normal response process.

Normal response process comprises following state transitions:

State transitions 1: this state transitions is that RSU sends the routine operation (the DL-DATA-ACK primitive specified in use standard) of data to OBU.

State transitions 2: this state transitions be exchanges data between RSU and OBU (INFO<>NULL) routine operation (from state in ENV 12795 and ARIB STD-T75 different), INFO is the data sending to OBU.DSRC agreement specify only two kinds of data delivery service between RSU and OBU: 1. confirm connectionless-mode data delivery service (DL-DATA-ACK)---and RSU sends out data to OBU; 2. connectionless-mode data exchange service (DL-REPLY) is confirmed---RSU says the word data to OBU, and fetches response data from OBU.Do not allow RSU only to fetch data (INFO=NULL) from OBU, therefore must limit INFO<>NULL.In day Europe superscript standard, there is mistake in this, specify that INFO can not be sky, the regulation of this and China GB GB/T 20851.2-2007 requires and incompatible.When using application layer retransmission data request command to complete delayed response, SAVE operation only returns " Processing " conditional code from application layer to LLC sublayer.

More particularly, there is event RECEIVE_ACn_CMD (SQC=V (RI), P=0, INFO<>NULL) and RECEIVE_STATUS ()=OK time, namely, when the order PDU received retransmits order, without the need to fetch data from board units and information field for empty, and when ordering the information field of PDU to receive successfully, action DATA_ACK_INDICATION and SEND_ACn_RSP (SQR=1-SQC is taked in the LLC sublayer of board units, F=0, C=OK, R=NR, LSDU=NULL), namely, the LLC sublayer of board units sends the data message in order PDU to application layer, and the data in the information field of response pdus are set to sky, empty confirmation Frame is sent to roadside unit, and

There is event RECEIVE_ACn_CMD (SQC=V (RI), P=1, INFO<>NULL), RECEIVE_STATUS ()=OK and ACCESS ()=OK time, namely, when the order PDU received retransmits order, need to fetch data from board units, information field is not empty, the information field of order PDU receives successfully, and the order PDU response data of asking exist and available time, action DELETE_SAVE_BUFFER is taked in the LLC sublayer of board units, REPLY_INDICATION (LSDU=INFO), SAVE:=GIVEN_LSDU, REPLY_UPDATE_STATUS_INDICATION and SEND_ACn_RSP (SQR=1-SQC, F=1, C=OK, R=OK, LSDU=SAVE), the data stored in the LLC sublayer delete buffer of i.e. board units, send the data in order PDU to application layer, data application layer provided are stored in described buffering area, notice application layer upgrades, data in the information field of the data being stored in buffering area responsively PDU are sent back to roadside unit, and the responsive state designator in the state subdomain of the information field of response pdus is set to indicate and has comprised asked data.

About the various functions of the such as ACCESS () here occurring and will occur hereinafter, the event of such as RECEIVE_ACn_CMD and action and the parameters such as parameters and such as SEND_ACn_RSP, simply illustrate in the lump at this, its detailed description can see the relevant regulations in DSRC GB GB/T 20851.2-2007.

(A) power function describes

The return value of following function function is used for the value limiting or provide protocol action to event.

(1) RECEIVE_STATUS (): returning the result of the order PDU information field received is successfully or the instruction of failure, namely returns CCCC part in the LLC status field of this order of response.

(2) ACCESS (): whether the response (LSDU) that return command PDU asks is current can use, namely returns RRRR part in the LLC status field of this order of response.

(B) event description

In the state transition table of receiving unit, event is assert by following condition.Only have ready conditions as true time just confirms that this event occurs.

(1) REPLY_UPDATE_REQUEST: application layer delivers a DL-REPLY-UPDATE.request primitive to LLC sublayer.

(2) RECEIVE_ACnCMD (SQC, P, INFO): media access control sublayer delivers a MA-DATA.indication primitive to LLC sublayer, wherein comprises an ACn order PDU.

8th bit of the command sequence bit SQC(LLC control domain in LLC control domain, that is n-bit) be " 0 " when PDU is AC0 order, be " 1 " when PDU is AC1 order.There is following possible parameter value in present event:

The value of SQC=V (RI) SQC equals V (RI) state variable of this receiving unit or this V (RI) shape

State variable does not exist.This shows that order PDU is not the order retransferred, but

The order transmitted first.

V (RI) state variable of SQC<>V (RI) this receiving unit exists, and unequal with the value of SQC.

This shows that order PDU is the order retransferred.The LLC sublayer of board units exists

After receiving a PDU order first, the V of self (RI) state variable can be put

For the radix-minus-one complement of the SQC in PDU order, therefore, if this PDU order is weighed

New transmission, V (RI) state variable of the LLC sublayer of that board units exist and also with

SQC in this PDU order is different, and this just shows that order PDU retransfers

Order.

P bit in P=0 LLC control domain is " 0 ".This show order PDU be roadside unit to

Board units sends data.

P bit in P=1 LLC control domain is " 1 ".This shows that order PDU is roadside unit

With board units swap data.

Information field in INFO=NULL order is empty (length is 0).

Information field non-NULL in INFO<>NULL order.

Information field in INFO order is empty (=NULL), or non-NULL (<>NULL).

(3) RECEIVE_STATUS ()=OK: the information field in order PDU receives successfully and can be delivered to user.

(4) RECEIVE_STATUS () <>OK: the information field in order PDU takes defeat and maybe can not be delivered to user.

(5) ACCESS ()=OK: the order PDU response LSDU that ask exists and available.

(6) ACCESS () <>OK: the response LSDU that order PDU asks does not exist; Or this LSDU exists but cannot access.

(C) action description

(1) SAVE:=GIVEN_LSDU: left in the SAVE buffering area of LLC sublayer by the LSDU that DL-REPLY-UPDATE.request primitive provides, makes it be in transmission ready state.The position of SAVE buffering area is associated with LSAP in this primitive, and new LSDU will replace this LSAP any LSDU held before this.

(2) SEND_ACn_RSP (SQR, F, C, R, LSDU): deliver a MA-DATA.request primitive to media access control sublayer, wherein comprises an ACn response pdus.

8th bit of the response sequence bit SQR(LLC control domain in LLC control domain, that is n-bit) be " 0 " when PDU is AC0 response, be " 1 " when PDU is AC1 response.There is following parameter value in this action:

SQR=1-SQC SQR is set to the SQC radix-minus-one complement received.

The F bit of F=0 LLC control domain is set to " 0 ".

The F bit of F=1 LLC control domain is set to " 1 ".

The CCCC part of C=OK LLC state subdomain is set to code " OK "

(receiving successfully).

The CCCC part of C=RECEIVE_STATUS () LLC state subdomain is set to

The return value of RECEIVE_STATUS power function.

The CCCC part of C=V (RB) LLC state subdomain is set to and receives

V (RB) state variable of ordering the link address of PDU to be correlated with

Value.

The RRRR part of R=NR LLC state subdomain is set to code " NR "

(not asking to respond LSDU).

The RRRR part of R=NE LLC state subdomain is set to code " NE "

(not submitting response LSDU to).Indicate by this state, road

Side unit can know clearly that asked data are not yet ready, still

Need to wait for.

The RRRR part of R=RS LLC state subdomain is set to code " RS " (no

Can perform or unactivated service).Indicate by this state, road

Side unit can know clearly that sent order PDU is not yet

The function of enabling, does not still support at present.

The RRRR part of R=OK LLC state subdomain is set to code " OK "

(response data comprises).Indicate by this state, trackside list

Unit can know clearly that asked data are included in response

In PDU.

The RRRR part of R=ACCESS () LLC state subdomain is set to ACCESS merit

The return value of energy function.

LSDU subdomain during LSDU=NULL LLC responds is empty (length is 0).

LSDU subdomain in LSDU=SAVE response contains and is kept at this LSAP's

The LSDU being in ready state in SAVE buffering area.

Note: in RSU, for OBU response medium slot should follow ACn order closely after distribute immediately.

(3) DATA_ACK_INDICATION:LLC sublayer comprises the DL-DATA-ACK.indication primitive of LSDU to application layer transmission one, and this LSDU is the order PDU information field received.

(4) REPLY_INDICATION (LSDU): a DL-REPLY.indication primitive is transmitted to application layer in LLC sublayer.There is following parameter value in this action:

LSDU=INFO transmits a LSDU to application layer, and this LSDU is the order PDU received

Information field (this territory may be empty).

LSDU=NULL transmits an empty LSDU to application layer.

(5) a DL-REPLY-UPDATE-STATUS.indication primitive is transmitted to application layer in REPLY_UPDATE_STATUS_INDICATION:LLC sublayer.

(6) V (RI) :=1-SQC: V (RI) state variable in receiving unit is set to the radix-minus-one complement of SQC in the order PDU received.

(7) V (RB) :=OK: V (RB) state variable of receiving unit is set to code " OK " (receiving successfully).

(8) V (RB) :=RECEIVE_STATUS (): V (RB) state variable of receiving unit is set to the return value of RECEIVE_STATUS power function.

(9) DELETE_SAVE_BUFFER: delete the data in SAVE buffering area, or mark data are wherein " use/invalid ".Known in conjunction with above and following state-transition table, state transitions 2,3 time, namely receive roadside unit when needing non-re-transmissions of swap data to order, this action is taked in the LLC sublayer of board units.Thus, previous asked error in data can be avoided to send to roadside unit.

2.1.2 delayed response process

Can processing command PDU in the LLC sublayer of board units, but processing speed is comparatively slow, and when can not complete within the link samsara time specified, OBU assembly carries out delayed response process.

Delayed response process comprises following state transitions:

State transitions 3: this state transitions occurs when using ACn order to occur delayed response, now asked data still unavailable (unripe).With mark Europe superscript and day in state unlike, use DL-REPLY.indication primitive herein, instead of DL-DATA-ACK.indication primitive.Reason is, be RSU will with OBU swap data, what RSU end sent is DL-REPLY.requeset instruction, according to national standard, OBU holds the nature be used to indicate should be that DL-REPLY.indication(when sending instructions under application layer, clear stipulaties is had, the 6.2.4.8 data flow con-trol see APP layer standard) to flow control parameters FlowControl.This just meets the link samsara of the regulation of standard " general introduction of 9.2.2 reciprocal process ", and should not use DL-DATA-ACK.indication.In addition, the RRRR part of LLC status field is designated as " response LSDU never (by upper strata) submits to ", i.e. R=NE, and thus, delayed response appears in notice roadside unit, meanwhile, waits for that application layer provides data.

State transitions 4:LLC sublayer receives a DL-REPLY-UPDATE request of sending from LLC sublayer user (APP layer), and a LSDU is preserved, for transfer request after a while in request LLC sublayer.

When state transitions " delayed data response ", the data of application layer notice previous Request are ready, and are stored in the SAVE buffering area of LLC sublayer.According to the difference of specific implementation, OBU will utilize the ACn command request of next re-transmission or utilize a UI order to send the data being stored in SAVE buffering area.

More particularly, there is event RECEIVE_ACn_CMD (SQC=V (RI), P=1, INFO<>NULL), RECEIVE_STATUS ()=OK and ACCESS () <>OK time, namely, when the order PDU received retransmits order, need to fetch data from board units, information field is not empty, the information field of order PDU receives successfully, and the order PDU response data of asking still unavailable time, take action DELETE_SAVE_BUFFER, REPLY_INDICATION (LSDU=INFO), with SEND_ACn_RSP (SQR=1-SQC, F=1, C=OK, R=NE, LSDU=NULL), the data stored in the LLC sublayer delete buffer of i.e. board units, send the data in order PDU to application layer, data in the information field of response pdus are set to sky, and described responsive state designator is set to instruction response data not yet submit to.Simultaneously, LLC sublayer waits for that application layer provides data, until there is event REPLY_UPDATE_REQUEST, namely application layer notifies to LLC sublayer that the data of asking are ready and indicates LLC sublayer to store this data, action SAVE:=GIVEN_LSDU and REPLY_UPDATE_STATUS_INDICATION is taked in LLC sublayer after being notified, namely receive the data of asking and described data are stored in the buffer, and notifying that application layer upgrades.

Here, when ordering the PDU response data of asking still unavailable, the data stored in the LLC sublayer delete buffer of board units, or mark data are wherein " use/invalid ".Like this, previous asked error in data can be avoided to send to roadside unit.Further, in response pdus, responsive state designator is set to instruction response data and not yet submits to by the LLC sublayer of board units, indicate by this state, roadside unit can know clearly that asked data are not yet ready, still needs to wait for, and can not make error understanding to response data.Meanwhile, when application layer to notify that to LLC sublayer the data of asking are ready, LLC sublayer after the data are stored, can utilize the next ACn command request that retransmits or utilize a UI order to send the data being stored in SAVE buffering area.Like this, even if can not return response data in time, this situation also can be informed to roadside unit by the LLC sublayer of board units in time, and very fast when meeting with a response data response data is supplied to roadside unit.

According to above state transitions 2,3,4 visible, according to type 3 receiving unit of the present invention, i.e. OBU assembly, can tackle the situation of roadside unit requirement swap data well.In this case, the past data that first the LLC sublayer of board units of the present invention stores in delete buffer, then the response data received from application layer is stored in the buffer, can guarantee thus to send to the data of roadside unit to be the data that roadside unit is asked, avoid previous error in data to send to roadside unit.And, when board units cannot return institute's request msg in time, the LLC sublayer of board units notifies that in response pdus roadside unit response data is not yet submitted to, and very fast when data can be met with a response response data being supplied to roadside unit, this is also that other prior aries institutes are irrealizable.

About delayed response process, applicant has carried out explanation specifically in another application, and those skilled in the art can carry out reference.

2.1.3 exception response process

When order the wrong or board units of the reception of PDU LLC sublayer can not processing command PDU, OBU assembly carries out exception response process.

Exception response process comprises following state transitions:

State transitions 5: represent that OBU have received synchronous (Re-Synchronisation) order again.DSRC protocol realization does not support this kind of command mode, therefore carries out mistake instruction with this response.Here, the RRRR of LLC status field part is set to be designated as unrealized or unactivated service, i.e. R=RS.And in Japan, European standard, R=NR is set with reference to the regulation of IEEE 802.2, represent " success does not ask to respond LSDU ", and do not comprise this function in DSRC agreement, therefore the standard regulation here in Japan and Europe is incorrect.

State transitions 6,7,9: these three transfers all belong to abnormal conditions, because the order received is wrong (RECEIVE_STATUS () <>OK), likely RSU have issued the instruction of mistake, is likely occurred mistake in order data transmitting procedure.In these three kinds of situations, board units returns to roadside unit the response that instruction exists reception mistake.

State transitions 8: this state transitions is the situation that RSU only obtains data (INFO=NULL) from OBU, this DSRC protocol realization does not support this state transitions, therefore carry out mistake instruction with this response, the RRRR part of LLC status field is designated as unrealized or unactivated service, i.e. R=RS.

More particularly, when there is event RECEIVE_STATUS () <>OK, namely when taking defeat to the information field of order PDU, action SEND_ACn_RSP (SQR=1-SQC, F=0, C=RECEIVE_STATUS () are taked in the LLC sublayer of board units, R=NR, LSDU=NULL), namely in the response pdus sent to roadside unit, the accepting state designator in the state subdomain of information field is set to take defeat; Further,

There is event RECEIVE_STATUS ()=OK and RECEIVE_ACn_CMD (INFO=NULL) time, but namely when board units to order PDU information field receives successfully information field be sky time, board units takes action SEND_ACn_RSP (SQR=1-SQC, F=0, C=OK, R=RS, LSDU=NULL), namely, in the response pdus sent to roadside unit, the service of being set to by the responsive state designator in the state subdomain of information field not yet activates.This is the situation that DSRC agreement is not supported.

2.1.4 retransmit response process

When the order PDU received is retransferring of the order be once conveyed through, OBU assembly carries out re-transmission response process.

Retransmit response process and comprise following state transitions:

State transitions 10: receive and retransmit order (repetition of state transitions 1 or state transitions 5), confirms Frame by the DLL causing repeating transmission one empty.

State transitions 11: receive and retransmit order (repetition of state transitions 2), the responsive data frame of carrying the data of asking to some extent will be retransmitted.

State transitions 12: receive and retransmit order (repetition of state transitions 3 or state transitions 8), confirms Frame by the DLL causing repeating transmission one empty.

More particularly, there is event RECEIVE_ACn_CMD (SQC<>V (RI), P=0, INFO) time, namely when ordering PDU for re-transmission order and without the need to fetching data from board units, action SEND_ACn_RSP (SQR=1-SQC is taked in the LLC sublayer of board units, F=0, C=V (RB), R=NR, LSDU=NULL), be set to sky by the data in the information field of response pdus, send empty confirmation Frame to roadside unit;

There is event RECEIVE_ACn_CMD (SQC<>V (RI), P=1, INFO) and ACCESS ()=OK time, namely when order PDU is for retransmitting order and needing to fetch data from board units, and the order PDU response data of asking exist and available time, then action REPLY_INDICATION (LSDU=NULL) and SEND_ACn_RSP (SQR=1-SQC is taked in the LLC sublayer of board units, F=1, C=V (RB), R=OK, LSDU=SAVE), namely empty data are transmitted to application layer, data in the information field of the institute's request msg being stored in buffering area responsively PDU are sent back to roadside unit, and responsive state designator is set to indicate and has comprised asked data, and

There is event RECEIVE_ACn_CMD (SQC<>V (RI), P=1, INFO) and ACCESS () <>OK time, namely when order PDU is for retransmitting order and needing to fetch data from board units, and the order PDU response data of asking still unavailable time, then action SEND_ACn_RSP (SQR=1-SQC is taked in the LLC sublayer of board units, F=1, C=V (RB), R=NE, LSDU=NULL), sky is set to by the data in the information field of response pdus, empty confirmation Frame is sent to roadside unit.

2.2 type 3 sending assemblies (RSU assembly)

Type 3 sending assembly is responsible for transmitting ACn order PDU to a far-end LLC, is also responsible for receiving response pdus simultaneously, and resends order PDU when not receiving response.

Have and confirm that connectionless type 3 agreement allows each special SAP ¹there is (being not yet identified) order PDU of " not completing ".Sending assembly uses the transmission sequence state variable V (SI) of oneself to determine LLC control domain code for once new transmission, or the validity of inspection response LLC control domain code.

The number of RSU sending assembly should to operate the OBU number carrying out communicating identical with type of service in communication zone 3.

Each sending assembly has three kinds of states: IDLE, WAIT_A and WAIT_R, i.e. idle state, wait acknowledge state and wait data mode.Under IDLE state, sending assembly can process the request from application layer, sends a new order PDU.Under WAIT_A and WAIT_R state, this assembly can only distally receive response or carry out data re-transmission in case of overtime by LLC.Under WAIT_A state, sending assembly waits for the confirmation of the type 3 called by DL-DATA-ACK.request primitive previously transmitted being ordered to PDU, namely expects the confirmation received not with response data.Under WAIT_R state, sending assembly waits for the confirmation of the type 3 called by DL-REPLY.request primitive previously transmitted being ordered to PDU, namely expects the confirmation received with response data.The state transition diagram of this assembly as shown in Figure 4.

The LLC sublayer of roadside unit is according to current residing state, from the order PDU of application layer reception and the response pdus from board units reception, be set with various states transfer case, various state transitions situation is set in conjunction with specific event and action by standardized event and action.The process of this assembly can be divided into: normal transmission processing, normally receive process, resend process, abnormal reception processes and failure handling.

2.2.1 normal transmission processing

The LLC sublayer of roadside unit sends the order PDU transmitted from application layer in an idle state to board units through media access control sublayer, carry out wait acknowledge state subsequently or wait for data mode, this is the normal transmission processing of RSU assembly.

Normal transmission processing comprises following state transitions:

State transitions 1: this state transitions only transmits data for RSU to OBU.

State transitions 2: this state transitions is for RSU and with exchanging (transmit and fetch) data between OBU.

More particularly, in an idle state, when there is event DATA_ACK_REQUEST, namely when application layer instruction sends data to board units, action SEND_ACn_CMD (SQC=V (SI), P=0) is taked in the LLC sublayer of roadside unit), namely send order PDU to board units, this order PDU indicates and sends data, enters wait acknowledge state subsequently; And

In an idle state, when there is event REPLY_REQUEST, namely when application layer instruction is with board units swap data, action SEND_ACn_CMD (SQC=V (SI) is taked in the LLC sublayer of roadside unit, P=1)), namely send order PDU, this order PDU to board units and indicate swap data, enter wait data mode subsequently.

About event and action and the parameters such as parameters and such as SEND_ACn_CMD of the such as RECEIVE_ACn_RSP here occurring and will occur hereinafter, simply illustrate in the lump at this, its detailed description can see the relevant regulations in DSRC GB GB/T 20851.2-2007.

(A) event description

In the state transition table of sending assembly, event is assert by following condition.Only have ready conditions as true time just confirms that this event occurs.

(1) DATA_ACK_REQUEST: application layer delivers a DL-DATA-ACK.request primitive to LLC sublayer.

(2) REPLY_REQUEST: application layer delivers a DL-REPLY.request primitive to LLC sublayer.

(3) RECEIVE_ACn_RSP (SQR, R, LSDU): media access control sublayer delivers a MA-DATA.indication service primitive to LLC sublayer, wherein comprises ACn response pdus.

There is following parameter value in present event:

SQR=V (SI) SQR is equal with V (SI) state variable of this sending assembly.This shows response pdus

There is frame timing error.

V (SI) state variable of SQR<>V (SI) SQR and this sending assembly is unequal.This shows response

The frame sequential of PDU is correct.

In the state subdomain of the response pdus that R=OK receives, RRRR part is designated as " OK "

State (indicating it to comprise response data).

In the state subdomain of the response pdus that R<>OK receives, RRRR part is designated as except " OK "

Outer other states (instruction does not wherein comprise response data).

LSDU subdomain in LSDU=NULL response is empty (length is 0).

LSDU subdomain non-NULL in LSDU<>NULL response.

(4) ACK_TIMER_EXPIRED: confirmation timer (namely corresponding to the timer of specific dedicated link address) the time-out be associated with this sending assembly.

(5) RETRY_COUNT<N11: the retransmission count of this sending assembly is less than logical links Parameter N 11.Logical links Parameter N 11 is the maximum number of times of transmission allowed.

(6) RETRY_COUNT>=N11: the retransmission count of this sending assembly is more than or equal to logical links Parameter N 11.

(B) action description

(1) SEND_ACn_CMD (SQC, P): transmit a MA-DATA.request service primitive to media access control sublayer, wherein comprises ACn order PDU.

There is following parameters value in this action:

SQC is set to the value of this sending assembly V (SI) state variable by SQC=V (SI).If V (SI)

State variable does not exist, then create the V (SI) that a value is " 0 "; Otherwise make

With V (SI) currency.

The P bit reset of P=0 order.This shows that order PDU is that roadside unit is to vehicle-mounted list

Unit sends data.

The P bit set of P=1 order.This shows that order PDU is roadside unit and vehicle-mounted list

Unit's swap data.

RR parameter in MA-DATA.request service primitive should be set to " 1 ", in order to distribute a dedicated uplink window.This window will be used for the response message transmitting expection.

(2) RESEND_OLD_CMD: transmit a MA-DATA.request service primitive to media access control sublayer, this primitive comprises the nearest ACn order PDU transmitted by this sending assembly.

RR parameter in MA-DATA.request service primitive should be set to " 1 ", in order to distribute a dedicated uplink window.This window will be used for the response message transmitting expection.

(3) START_ACK_TIMER: the confirmation timer starting this sending assembly.

(4) CANCEL_ACK_TIMER: the confirmation timer cancelling this sending assembly.

(5) DATA_ACK_STATUS_INDICATION (STATUS): transmit a DL-DATA-ACK-STATUS.indication service primitive to application layer.There is following parameter value in this action:

STATUS=UNSUCCESSFUL STATUS state parameter is set to instruction and does not become

Merit confirmation of receipt.

STATUS=STATUS_SUBFIELD STATUS state parameter is set to the sound received

Answer the state returned in PDU.

(6) REPLY_STATUS_INDICATION (STATUS, LSDU): transmit a DL-REPLY-STATUS.indication service primitive to application layer.There is following parameter value in this action:

STATUS=UNSUCCESSFUL STATUS state parameter is set to instruction and does not successfully connect

Receive and confirm.

STATUS=STATUS_SUBFIELD STATUS state parameter is set to the response received

The state returned in PDU.

STATUS=PE STATUS state parameter is set to PE state, and (agreement is wrong

By mistake).

LSDU=NULL data parameters LSDU is empty.

Comprise by accordingly in LSDU=GIVEN_LSDU data parameters LSDU

The LSDU that MA-DATA.indication service primitive provides.

(7) V (SI) :=1-V (SI): by V (SI) the state variable negate of this sending assembly.

(8) RETRY_COUNT:=0: the retransmission counter of this sending assembly is set to " 0 ".

(9) RETRY_COUNT:=RETRY_COUNT+1: the value of the retransmission counter of this sending assembly is added 1.

(10) REPORT_STATUS (ILLEGAL_LSDU): report layer management entity, have received the LSDU that does not meet type 3LLC agreement.

2.2.2 normally receive process

The LLC sublayer of roadside unit, in wait acknowledge state or under waiting for data mode, receives the normal response pdus from board units, returns idle condition subsequently, and this is the normal reception process of RSU assembly.

Normal reception process comprises following state transitions:

State transitions 3: receive the order acknowledgement frame not with response data, the order sent in state transitions 1 is successfully completed.

State transitions 4: receive the order acknowledgement frame with response data, the order sent in state transitions 2 is successfully completed.

More particularly, event RECEIVE_ACn_RSP (SQR<>V (SI) is there is under wait acknowledge state, LSDU=NULL) time), namely when to receive from the data of board units be empty response pdus, action DATA_ACK_STATUS_INDICATION (STATUS=STATUS_SUBFIELD) is taked in the LLC sublayer of roadside unit, by the state transfer returned in response pdus to application layer, enter idle condition subsequently, and

Event RECEIVE_ACn_RSP (SQR<>V (SI) is there is under wait data mode, R=OK) time), namely when receive from board units responsive state designator instruction comprised the response pdus of asked data time, action REPLY_STATUS_INDICATION (STATUS=STATUS_SUBFIELD is taked in the LLC sublayer of roadside unit, LSDU=GIVED_LSDU)), pass to application layer by the state returned in response pdus and response data, enter idle condition subsequently.

2.2.3 process is resend

The LLC sublayer of roadside unit resends first previous order PDU in wait acknowledge state or under waiting for data mode to board units, still remains on wait acknowledge state or wait data mode subsequently, and what this was RSU assembly resends process.

Resend process and comprise following state transitions:

State transitions 5: confirm timer expiry, resend the order sent in state transitions 1.If N11=1, then fill order is not retransmitted.

State transitions 6: confirm timer expiry, resend the order sent in state transitions 2.If N11=1, then fill order is not retransmitted.

More particularly, in wait acknowledge state or under wait data mode, when there is event ACK_TIMER_EXPIRED and RETRY_COUNT<N11 time, namely when wait-for-response PDU stand-by period time-out and not yet reach allow transmission times time, action RESEND_OLD_CMD is taked in the LLC sublayer of roadside unit, namely resend first previous order PDU to board units, still remain on wait acknowledge state subsequently or wait for data mode.

Process is received 2.2.4 abnormal

The LLC sublayer of roadside unit receives abnormal response pdus, enters idle condition subsequently or remains on wait acknowledge state or wait for data mode, and this exception being RSU assembly receives process.

Abnormal reception process comprises following state transitions:

State transitions 7: this state transitions can not occur, because just effective when only receiving the response of ACn order under WAIT_R or WAIT_A state.

State transitions 8: contain the data that should not exist in the order acknowledgement frame received: LSDU<>NULL, and the state before transfer is WAIT_A.

State transitions 9: the response frame timing error (SQR mistake) received, this frame is abandoned.

State transitions 10: receive order acknowledgement frame, the order sent in state transitions 2 completes, but does not obtain asked data.

State transitions 11: the response frame timing error (SQR mistake) received, this frame is abandoned.

More particularly, when there is event RECEIVE_ACn_RSP in an idle state, when namely receiving the response pdus of board units, any action is not carried out in the LLC sublayer of roadside unit, remains on idle condition;

Event RECEIVE_ACn_RSP (SQR<>V (SI) is there is under wait acknowledge state, LSDU<>NULL)), when namely receiving data from board units for empty response pdus, action DATA_ACK_STATUS_INDICATION (STATUS=PE) and REPORT_STATUS (ILLEGAL_LSDU) is taked in the LLC sublayer of roadside unit, namely notify application layer protocol mistake and report that layer management entity have received the response data of protocol error, enter idle condition subsequently, and

Event RECEIVE_ACn_RSP (SQR<>V (SI) is there is under wait data mode, R<>OK) time), namely when receive from the responsive state designator in the response pdus of board units do not indicate comprised asked data time, action REPLY_STATUS_INDICATION (STATUS=STATUSSUBFIELD is taked in the LLC sublayer of roadside unit, LSDU=NULL)), data by the state returned in response pdus and sky pass to application layer, enter idle condition subsequently, and

In wait acknowledge state or when there is event RECEIVE_ACn_RSP (SQR=V (SI)) under waiting for data mode, during the response pdus frame timing error namely received, any action is not carried out in the LLC sublayer of roadside unit, remains on wait acknowledge state or waits for data mode.

2.2.5 failure handling

The LLC sublayer of roadside unit is in the transmission times specified and fail within the time to obtain confirmation response, and notify unsuccessfully to application layer, this is the failure handling of RSU assembly.

Failure handling comprises following state transitions:

State transitions 12: meet with a response not yet when having reached the maximum number of retransmissions of order, now stops the repeating transmission of ACn order.

State transitions 13: the maximum retransmission device number of times having reached order meets with a response not yet, now stops the repeating transmission of ACn order.

More particularly, wait acknowledge state or wait for there is event ACK_TIMER_EXPIRED under data mode and RETRY_COUNT>=N11 time, namely wait-for-response PDU stand-by period time-out and reached allow transmission times time, action DATA_ACK_STATUS_INDICATION (STATUS=UNSUCCESSFUL is taked in the LLC sublayer of roadside unit, LSDU=NULL), namely transmit unsuccessfully to application layer notice, enter idle condition subsequently.

Conclusion

Above labor and explanation are carried out to the finite state transfer design of the LLC sublayer in DSRC communication.State transitions according to LLC sublayer of the present invention designs, not only can adapt to the application characteristic that the response speed of two-piece type electronic tag board units is slower, and the method not only can have been carried out Design and implementation by hardware (chip) but also can have been realized by software, comparatively complicated controlling functions can be realized, and for minimizing somersault and power consumption significant.

Claims (14)

1. for a LLC sublayer condition control method for the Dedicated Short Range Communications, of intelligent transportation field, wherein,

Connect without under affirmation mode in nothing, the LLC sublayer of roadside unit and board units receives the order PDU of the other side in the ready state during via MAC layer, this order PDU is transferred to application layer to be processed by application layer, and, when the order PDU receiving application layer sends request, send this order PDU by media access control sublayer; Further,

Under nothing is connected with affirmation mode, when the order PDU that the LLC sublayer of roadside unit receives application layer in an idle state sends request, this order PDU is sent to board units by media access control sublayer, enter wait state subsequently, after receiving the correct response pdus of board units, get back to idle condition; When the LLC sublayer of board units receives the order PDU of roadside unit transmission via media access control sublayer in the ready state, according to the order PDU received, after selectivity carries out state transitions process from the various states transfer processing preset, get back to ready state; Wherein, the various state transitions process of the LLC sublayer of described board units are set in conjunction with specific event and action by standardized event and action, and beam back different response pdus respectively to roadside unit, these state transitions process are divided into:

Normal response process, wherein, the LLC sublayer of board units can processing command PDU in time;

Delayed response process, wherein, the LLC sublayer of board units can processing command PDU, but processing speed is slower;

Exception response process, wherein, the reception of order PDU is wrong, or the LLC sublayer of board units can not processing command PDU; And

Retransmit response process, wherein, order PDU is retransferring of a upper order be conveyed through,

And, wherein, the LLC sublayer of described roadside unit is according to current residing state, from the order PDU of application layer reception and the response pdus from board units reception, process according to the various states transfer case preset, various state transitions situation is set in conjunction with specific event and action by standardized event and action;

Wherein, the state transitions process of the LLC sublayer of roadside unit is divided into:

Normal transmission processing, wherein, the LLC sublayer of roadside unit sends the order PDU transmitted from application layer in an idle state to board units through media access control sublayer, carries out wait acknowledge state subsequently or waits for data mode;

Normal reception process, wherein, the LLC sublayer of roadside unit, in wait acknowledge state or under waiting for data mode, receives the normal response pdus from board units, returns idle condition subsequently;

Resend process, wherein, the LLC sublayer of roadside unit resends first previous order PDU in wait acknowledge state or under waiting for data mode to board units, still remains on wait acknowledge state subsequently or waits for data mode;

Extremely receive process, wherein, the LLC sublayer of roadside unit receives abnormal response pdus, enters idle condition subsequently or remains on wait acknowledge state or wait for data mode; And

Failure handling, wherein, the LLC sublayer of roadside unit notifies unsuccessfully to application layer.

2. LLC sublayer according to claim 1 condition control method, wherein, described standardized event and action are event primitive and the primitive acts of regulation in DSRC GB GB/T 20851.2-2007.

3. LLC sublayer according to claim 1 and 2 condition control method, wherein, the normal response process of board units LLC sublayer comprises following process:

There is event RECEIVE_ACn_CMD (SQC=V (RI), P=0, INFO<>NULL) and RECEIVE_STATUS ()=OK time, namely, when the order PDU received retransmits order, without the need to fetch data from board units and information field for empty, and when ordering the information field of PDU to receive successfully, action DATA_ACK_INDICATION and SEND_ACn_RSP (SQR=1-SQC is taked in the LLC sublayer of board units, F=0, C=OK, R=NR, LSDU=NULL), namely, the LLC sublayer of board units sends the data message in order PDU to application layer, and the data in the information field of response pdus are set to sky, empty confirmation Frame is sent to roadside unit, and

There is event RECEIVE_ACn_CMD (SQC=V (RI), P=1, INFO<>NULL), RECEIVE_STATUS ()=OK and ACCESS ()=OK time, namely, when the order PDU received retransmits order, need to fetch data from board units, information field is not empty, the information field of order PDU receives successfully, and the order PDU response data of asking exist and available time, action DELETE_SAVE_BUFFER is taked in the LLC sublayer of board units, REPLY_INDICATION (LSDU=INFO), SAVE:=GIVEN_LSDU, REPLY_UPDATE_STATUS_INDICATION and SEND_ACn_RSP (SQR=1-SQC, F=1, C=OK, R=OK, LSDU=SAVE), the data stored in the LLC sublayer delete buffer of i.e. board units, send the data in order PDU to application layer, data application layer provided are stored in described buffering area, notice application layer upgrades, data in the information field of the data being stored in buffering area responsively PDU are sent back to roadside unit, and the responsive state designator in the state subdomain of the information field of response pdus is set to indicate and has comprised asked data.

4. LLC sublayer according to claim 3 condition control method, wherein, the delayed response process of board units comprises following process:

There is event RECEIVE_ACn_CMD (SQC=V (RI), P=1, INFO<>NULL), RECEIVE_STATUS ()=OK and ACCESS () <>OK time, namely, when the order PDU received retransmits order, need to fetch data from board units, information field is not empty, the information field of order PDU receives successfully, and the order PDU response data of asking still unavailable time, take action DELETE_SAVE_BUFFER, REPLY_INDICATION (LSDU=INFO), with SEND_ACn_RSP (SQR=1-SQC, F=1, C=OK, R=NE, LSDU=NULL), the data stored in the LLC sublayer delete buffer of i.e. board units, send the data in order PDU to application layer, data in the information field of response pdus are set to sky, and described responsive state designator is set to instruction response data not yet submit to, simultaneously, LLC sublayer waits for that application layer provides data.

5. LLC sublayer according to claim 4 condition control method, wherein, the LLC sublayer of board units is after sending the data in order PDU to application layer, wait for that application layer provides data, until there is event REPLY_UPDATE_REQUEST, namely application layer notifies to LLC sublayer that the data of asking are ready and indicates LLC sublayer to store this data, action SAVE:=GIVEN_LSDU and REPLY_UPDATE_STATUS_INDICATION is taked in LLC sublayer after being notified, namely receive the data of asking and described data are stored in the buffer, and notify that application layer upgrades.

6. LLC sublayer according to claim 1 and 2 condition control method, wherein, the exception response process of the LLC sublayer of board units comprises following process:

When there is event RECEIVE_STATUS () <>OK, namely when taking defeat to the information field of order PDU, action SEND_ACn_RSP (SQR=1-SQC is taked in the LLC sublayer of board units, F=0, C=RECEIVE_STATUS (), R=NR, LSDU=NULL), namely, in the response pdus sent to roadside unit, the accepting state designator in the state subdomain of information field is set to take defeat;

There is event RECEIVE_STATUS ()=OK and RECEIVE_ACn_CMD (INFO=NULL) time, but namely when board units to order PDU information field receives successfully information field be sky time, board units takes action SEND_ACn_RSP (SQR=1-SQC, F=0, C=OK, R=RS, LSDU=NULL), namely, in the response pdus sent to roadside unit, the service of being set to by the responsive state designator in the state subdomain of information field not yet activates.

7. LLC sublayer according to claim 1 and 2 condition control method, wherein, the re-transmission response process of the LLC sublayer of board units comprises following process:

There is event RECEIVE_ACn_CMD (SQC<>V (RI), P=0, INFO) time, namely when ordering PDU for re-transmission order and without the need to fetching data from board units, action SEND_ACn_RSP (SQR=1-SQC is taked in the LLC sublayer of board units, F=0, C=V (RB), R=NR, LSDU=NULL), be set to sky by the data in the information field of response pdus, send empty confirmation Frame to roadside unit;

There is event RECEIVE_ACn_CMD (SQC<>V (RI), P=1, INFO) and ACCESS ()=OK time, namely when order PDU is for retransmitting order and needing to fetch data from board units, and the order PDU response data of asking exist and available time, then action REPLY_INDICATION (LSDU=NULL) and SEND_ACn_RSP (SQR=1-SQC is taked in the LLC sublayer of board units, F=1, C=V (RB), R=OK, LSDU=SAVE), namely empty data are transmitted to application layer, data in the information field of the institute's request msg being stored in buffering area responsively PDU are sent back to roadside unit, and responsive state designator is set to indicate and has comprised asked data, and

There is event RECEIVE_ACn_CMD (SQC<>V (RI), P=1, INFO) and ACCESS () <>OK time, namely when order PDU is for retransmitting order and needing to fetch data from board units, and the order PDU response data of asking still unavailable time, then action SEND_ACn_RSP (SQR=1-SQC is taked in the LLC sublayer of board units, F=1, C=V (RB), R=NE, LSDU=NULL), sky is set to by the data in the information field of response pdus, empty confirmation Frame is sent to roadside unit.

8. LLC sublayer according to claim 1 and 2 condition control method, wherein, the state transitions of the LLC sublayer of board units is 12 kinds.

9. LLC sublayer according to claim 1 condition control method, wherein, the normal transmission processing of the LLC sublayer of roadside unit comprises following process:

In an idle state, when there is event DATA_ACK_REQUEST, namely when application layer instruction sends data to board units, action SEND_ACn_CMD (SQC=V (SI) is taked in the LLC sublayer of roadside unit, P=0)), namely send order PDU, this order PDU instruction to board units and send data, enter wait acknowledge state subsequently; And

In an idle state, when there is event REPLY_REQUEST, namely when application layer instruction is with board units swap data, action SEND_ACn_CMD (SQC=V (SI) is taked in the LLC sublayer of roadside unit, P=1)), namely send order PDU, this order PDU to board units and indicate swap data, enter wait data mode subsequently.

10. LLC sublayer according to claim 1 condition control method, wherein, the normal reception process of the LLC sublayer of roadside unit comprises following process:

Event RECEIVE_ACn_RSP (SQR<>V (SI) is there is under wait acknowledge state, LSDU=NULL) time), namely when to receive from the data of board units be empty response pdus, action DATA_ACK_STATUS_INDICATION (STATUS=STATUS_SUBFIELD) is taked in the LLC sublayer of roadside unit, by the state transfer returned in response pdus to application layer, enter idle condition subsequently, and

Event RECEIVE_ACn_RSP (SQR<>V (SI) is there is under wait data mode, R=OK) time), namely when receive from board units responsive state designator instruction comprised the response pdus of asked data time, action REPLY_STATUS_INDICATION (STATUS=STATUS_SUBFIELD is taked in the LLC sublayer of roadside unit, LSDU=GIVED_LSDU)), pass to application layer by the state returned in response pdus and response data, enter idle condition subsequently.

11. LLC sublayer according to claim 1 condition control methods, wherein, the process that resends of the LLC sublayer of roadside unit comprises following process:

In wait acknowledge state or under wait data mode, when there is event ACK_TIMER_EXPIRED and RETRY_COUNT<N11 time, namely when wait-for-response PDU stand-by period time-out and not yet reach allow transmission times time, action RESEND_OLD_CMD is taked in the LLC sublayer of roadside unit, namely resend first previous order PDU to board units, still remain on wait acknowledge state subsequently or wait for data mode.

12. LLC sublayer according to claim 1 condition control methods, wherein, the exception of the LLC sublayer of roadside unit receives process and comprises following process:

When there is event RECEIVE_ACn_RSP in an idle state, when namely receiving the response pdus of board units, any action is not carried out in the LLC sublayer of roadside unit, remains on idle condition;

Event RECEIVE_ACn_RSP (SQR<>V (SI) is there is under wait acknowledge state, LSDU<>NULL)), when namely receiving data from board units for empty response pdus, action DATA_ACK_STATUS_INDICATION (STATUS=PE) and REPORT_STATUS (ILLEGAL_LSDU) is taked in the LLC sublayer of roadside unit, namely notify application layer protocol mistake and report that layer management entity have received the response data of protocol error, enter idle condition subsequently, and

Event RECEIVE_ACn_RSP (SQR<>V (SI) is there is under wait data mode, R<>OK) time), namely when receive from the responsive state designator in the response pdus of board units do not indicate comprised asked data time, action REPLY_STATUS_INDICATION (STATUS=STATUS_SUBFIELD is taked in the LLC sublayer of roadside unit, LSDU=NULL)), data by the state returned in response pdus and sky pass to application layer, enter idle condition subsequently, and

In wait acknowledge state or when there is event RECEIVE_ACn_RSP (SQR=V (SI)) under waiting for data mode, during the response pdus frame timing error namely received, any action is not carried out in the LLC sublayer of roadside unit, remains on wait acknowledge state or waits for data mode.

13. LLC sublayer according to claim 1 condition control methods, wherein, the failure handling of the LLC sublayer of roadside unit comprises following process:

Wait acknowledge state or wait for there is event ACK_TIMER_EXPIRED under data mode and RETRY_COUNT>=N11 time, namely wait-for-response PDU stand-by period time-out and reached allow transmission times time, action DATA_ACK_STATUS_INDICATION (STATUS=UNSUCCESSFUL is taked in the LLC sublayer of roadside unit, LSDU=NULL), namely transmit unsuccessfully to application layer notice, enter idle condition subsequently.

14. LLC sublayer according to claim 1 condition control methods, wherein, the state transitions of the LLC sublayer of roadside unit is 13 kinds.