WO2012136019A1

WO2012136019A1 - Radio frequency identification system based communication method, apparatus and system

Info

Publication number: WO2012136019A1
Application number: PCT/CN2011/076088
Authority: WO
Inventors: 吴奇; 徐运; 刘金栋; 汪旭光
Original assignee: 中兴通讯股份有限公司
Priority date: 2011-04-02
Filing date: 2011-06-22
Publication date: 2012-10-11
Also published as: CN102737207A; CN102737207B

Abstract

A radio frequency identification system based communication method, apparatus and system are disclosed, which are used for implementing bi-directional communication between an electronic tag and a reader in the radio frequency identification system, saving battery power consumption in an active electronic tag, and guaranteeing communication stability between the electronic tag and the reader. Wherein, the method includes: receiving data frames sent by the reader in the current checking period, analyzing the data frames and extracting frame sequence numbers from preset fields, calculating waiting time required for the current checking period to enter into a channel idle state based on the extracted frame sequence numbers, selecting one timeslot from timeslots included in the current checking period when determining the reader is in the channel idle state, and transmitting messages to the reader based on the selected timeslot.

Description

Communication method, device and system based on radio frequency identification system

The present invention relates to the field of radio frequency identification, and in particular, to a communication method, device and system based on a radio frequency identification system. Background technique

At present, application systems based on Radio Frequency Identification (RFID) technology are widely used in the field of intelligent transportation. The RFID technology utilizes the radio frequency signal based on the spatial coupling transmission characteristic to realize the automatic recognition of the object in a non-contact manner. An RFID system generally includes a reader and an electronic tag, wherein the reader is a device that reads electronic tag information. The reader performs data transmission and reception in units of counting cycles, that is, an inventory period includes two stages of transmitting data and receiving data. According to different application scenarios, the number of transmitting data frames and the time slots included in one inventory period are included. The numbers are not the same.

Taking the route identification system of the expressway as an example, the RFID system is composed of a roadside base station (dedicated reader), a lane reader, and an electronic tag. At the entrance of the highway, the electronic tag is initialized by the lane reader; on the highway, the electronic tag interacts with the roadside base station and saves the necessary path information; at the highway exit, the electronic tag reads through the lane The card device reports the already stored path information for data processing. However, the communication between the roadside base station and the electronic tag is unidirectional, that is, only the roadside base station sends the path information to the electronic tag. With the continuous changes in market demand and the development of RFID technology, it is an inevitable trend to realize two-way communication between the roadside base station and the electronic tag.

In the time-based communication system, if two-way communication between the roadside base station and the electronic tag is implemented, channel idle detection is required, that is, the idle time period of the roadside base station in the current inventory period is determined to be selected during the idle time period. The slot transmits the information of the electronic tag to the roadside base station. Traditional The method performs channel idle detection based on Received Signal Strength Indication (RSSI), that is, the electronic tag monitors the strength of the received carrier signal, that is, RSSI, in real time, and determines that the channel is idle when determining that the RSSI is lower than the set threshold. status. However, the method is not applicable to active electronic tags. First, the detection of RSSI requires that the radio frequency circuit of the electronic tag is always in the radio frequency receiving state, and the energy consumption of the electronic tag battery is large; secondly, the detection of the RSSI is easily exposed to the outside world. Environmental interference affects the accuracy of the test results and reduces the stability of the RFID system communication. Summary of the invention

In view of the above, the present invention provides a communication method, device and system based on a radio frequency identification system for realizing two-way communication between an electronic tag and a reader in a radio frequency identification system, and saving battery energy consumption of the active electronic tag. Ensure the stability of communication between the electronic tag and the reader.

To solve the above technical problem, the specific technical solution provided by the embodiment of the present invention is as follows: A communication method based on a radio frequency identification system, including:

Receiving a data frame sent by the reader during the current inventory period;

Parsing the data frame and extracting a frame number from a predetermined field, calculating a duration of waiting for the current inventory period to enter a channel idle state based on the extracted frame number, and determining that the reader is a channel idle state, from the current Selecting one time slot from the time slots included in the inventory period;

A message is sent to the reader based on the selected time slot.

Before receiving the data frame sent by the reader in the current inventory period, the method further includes: presetting the format of the data frame sent by the reader, and presetting the frame number of the data frame in a predetermined field in the data frame.

And calculating, according to the extracted frame sequence number, a duration that the current inventory period needs to wait for entering the channel idle state, including: sending a time occupied by a single data frame according to a total time of sending and occupying in the current inventory period, and a predetermined field from the data frame The extracted frame number, and the time to wait for entering the channel idle state. When determining that the reader is in the channel idle state, selecting one time slot from the time slots included in the current inventory period includes: determining a number of time slots in the channel idle state in the current inventory period, and generating according to the number of time slots A random number, selecting a time slot corresponding to the random number.

When the random number is generated according to the number of time slots, the method includes: determining, according to the number of time slots, the number of bits occupied by the random number, and initializing the random number; determining whether the number of times of capturing reaches the number of bits occupied by the random number, if not reaching random Counting the number of bits, shifting the random number to the left by one bit, starting the timer and capturing the high frequency clock based on the low frequency clock, and using the value of the lowest bit of the captured data as the lowest bit of the random number And adding the number of captures to 1 and then determining whether the number of captures reaches the number of bits occupied by the random number; if the number of bits occupied by the random number is reached, the time slot corresponding to the random number is selected.

A communication device based on a radio frequency identification system, comprising:

a radio frequency chip, configured to receive a data frame sent by the reader during a current inventory period, and send a message to the reader based on a time slot selected by the central processing unit;

a central processing unit, configured to parse a data frame received by the radio frequency chip, and extract a frame serial number from a predetermined field, calculate a duration of waiting for the current inventory period to enter a channel idle state, and determine that the reader is In the channel idle state, one time slot is selected from the time slots included in the current inventory period.

Before the radio frequency chip receives the data frame sent by the reader in the current inventory period, the format of the data frame sent by the reader is preset, and the frame number of the data frame is preset in a predetermined field in the data frame.

The central processor calculates, according to the extracted frame sequence number, a duration that the current inventory period needs to wait for entering the channel idle state, specifically: time required for sending a single data frame according to the total time of transmission in the current inventory period, and the data from the data The frame number extracted from the predetermined field of the frame, and the time to wait for entering the channel idle state.

The central processor determines from the current inventory period packet when determining that the reader is in a channel idle state One time slot is selected, which is specifically: determining the number of time slots in the channel idle state in the current inventory period, and generating a random number according to the number of the time slots, and selecting the time slot corresponding to the random number.

The central processor generates a random number according to the number of time slots, specifically: determining, according to the number of time slots, the number of bits occupied by the random number, and initializing the random number; determining whether the number of times of capturing reaches the number of bits occupied by the random number, and if If the number of bits occupied by the random number is not reached, the random number is shifted to the left by one bit, the timer is started, and the high frequency clock is captured based on the low frequency clock, and the lowest bit of the captured data is used as the lowest bit of the random number. The value of the bit, and the number of times of the capture is incremented by one to determine whether the number of times of the capture reaches the number of bits occupied by the random number; if the number of bits occupied by the random number is reached, the time slot corresponding to the random number is selected.

A radio frequency identification based communication system, comprising:

a reader, configured to send a data frame to the electronic tag, and receive the message sent by the electronic tag; the electronic tag is configured to receive the data frame sent by the reader during the current inventory period, parse the data frame, and extract the frame serial number from the predetermined field And calculating, according to the extracted frame sequence number, a duration that the current inventory period needs to wait for entering the channel idle state, and determining that the reader is a channel idle state, selecting a time slot from the time slots included in the current inventory period, and A message is sent to the reader based on the selected time slot.

Based on the foregoing technical solution, in the embodiment of the present invention, after receiving the data frame sent by the reader in the current inventory period, the electronic tag parses the data frame and extracts the frame serial number from the predetermined field, and then calculates the current inventory period based on the extracted frame serial number. The length of time to wait for entering the channel idle state, and after waiting for the duration, determining that the reader is in the channel idle state, selecting the time slot to send a message to the reader, thereby implementing two-way communication between the electronic tag and the reader, and It does not increase the energy consumption of the active electronic tag on the battery, ensures the stability of communication between the electronic tag and the reader, and does not need to change the original hardware structure of the radio frequency communication system, and is simple to implement. DRAWINGS

1 is a schematic structural diagram of a radio frequency identification system according to an embodiment of the present invention;

2 is a schematic structural diagram of an electronic tag according to an embodiment of the present invention;

3 is a schematic flowchart of a communication method based on a radio frequency identification system according to an embodiment of the present invention; FIG. 4 is a schematic diagram of a composition of a check cycle of a reader according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of a format of a data frame generated by a reader in an embodiment of the present invention. detailed description

In order to realize the two-way communication between the electronic tag and the reader in the RFID system, and to save the battery energy consumption of the active electronic tag and ensure the stability of the communication between the electronic tag and the reader, the embodiment of the present invention provides a radio frequency based A communication method, apparatus, and system for identifying a system. The method is: the electronic tag receives a data frame sent by the reader during the current inventory period, parses the data frame, and extracts a frame serial number from a predetermined field, and calculates a duration to wait for the current inventory period to enter the channel idle state based on the extracted frame serial number, and When it is determined that the reader is in the channel idle state, one time slot is selected from the time slots included in the current inventory period, and a message is sent to the reader based on the selected time slot.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in FIG. 1, in the embodiment of the present invention, the RFID system is mainly composed of a reader 101 and an electronic tag 102, wherein

The reader 101 is configured to send a data frame to the electronic tag 102, and receive a message sent by the electronic tag 102;

The electronic tag 102 is configured to receive a data frame sent by the reader 101 during a current inventory period, parse the data frame, and extract a frame serial number from a predetermined field, and calculate, according to the extracted frame serial number, a duration that the current inventory period needs to wait for entering the channel idle state, When it is determined that the reader 101 is in the channel idle state, one slot is selected from the slots included in the current inventory period, and a message is transmitted to the reader 101 based on the selected slot.

As shown in FIG. 2, the electronic tag 102 mainly includes a central processing unit 201, a radio frequency chip 202, The battery and its peripheral circuit 203 and the antenna 204. In the embodiment of the present invention, the radio frequency chip 202 transmits the data frame sent by the reader in the current inventory period to the central processing unit 201 through the antenna 204, and sends a message to the reader based on the time slot selected by the central processing unit 201; The processor 201 is configured to parse the data frame and extract a frame sequence number from the predetermined field, and calculate, according to the extracted frame sequence number, a duration that the current inventory period needs to wait for entering the channel idle state, and when determining that the reader is in the channel idle state, the current inventory period includes One time slot is selected in the time slot; the radio frequency chip 202 is configured to send a message to the reader through the antenna 204 based on the selected time slot. The battery and its peripheral circuit 203 are used to supply power to the central processing unit 201.

Based on the above system architecture, as shown in FIG. 3, in the embodiment of the present invention, the detailed method flow for communication based on the radio frequency identification system is as follows:

Step 301: Receive a data frame sent by the reader during the current inventory period.

As shown in FIG. 4, the number of data frames and the number of time slots included in an inventory period of the reader are different according to the application scenario. In the embodiment of the present invention, an inventory period is set to include N. Data frames and time slots. In the embodiment of the present invention, before the electronic tag receiving reader sends the data frame in the current inventory period, the electronic tag needs to be configured as a timed wake mode, that is, parameters required for configuring the timed wake mode for the electronic tag, for example, sleep duration and wakeup. duration.

Preferably, in the electronic tag, before the radio frequency chip receives the data frame sent by the reader during the current inventory period, the central processor configures the radio frequency chip to be in a timed wake mode, and the central processor sends a control command to the radio frequency chip. The radio frequency chip is placed in a timed wake state to receive data frames transmitted by the reader during the current inventory period in the timed wake state.

Wherein, each time the electronic tag enters the timed wake state, the time of receiving the data frame sent by the reader for the first time in the timed wake state is recorded.

Step 302: Parse the data frame and extract a frame sequence number from the predetermined field, calculate a duration to wait for the current inventory period to enter the channel idle state based on the extracted frame sequence number, and determine that the reader is a channel. In the idle state, one slot is selected from the slots included in the current inventory period.

In the embodiment of the present invention, the format of the data frame sent by the reader is defined as shown in FIG. 5. After the original information field, that is, the frame header information and the reader information, a new field is added to save the current data in the added field. The frame number of the frame. Preferably, the added field is 2 bytes.

After parsing the data frame and extracting the frame number from the predetermined field, calculating a duration of waiting for the current inventory period to enter the channel idle state, specifically: sending the total time occupied by the current inventory period, sending the time occupied by the single data frame, and The frame number extracted from the predetermined field of the data frame, and the time to wait for the channel to idle.

The total time occupied by the current inventory cycle is 7; the time taken to send a single data frame is 7>, the time of receiving the data frame sent by the reader is 7:, and the frame number extracted from the predetermined field of the data frame is Then the formula for calculating the start time 进入] of entering the channel idle state is as follows:

T _{i =} T + T - N _f xT _f , then the time to wait for the idle state of the incoming channel is further calculated as: = 7· -7; = Γ - N _f xT _f .

In the embodiment of the present invention, in the electronic tag, the total time occupied by the central processor according to the current inventory cycle is 7; the time occupied by sending a single data frame is 7>, and the frame number extracted from the predetermined field of the data frame. For N, , calculate the time Δη to wait for entering the channel idle state, and according to the setting of the internal timer of the central processing unit, the radio frequency chip is in a sleep state, real-time monitoring the internal timer of the central processing unit, and in the timer After the set time has elapsed, it is determined that the idle state of the current inventory cycle is entered.

In the embodiment of the present invention, the number of time slots in the channel idle state in the current inventory period is determined, and the random number is generated according to the number of the time slots, and the random number is selected. The number of corresponding time slots.

If the number of time slots included in an inventory cycle is N _s , where each time slot occupies 7:, the start time of the message sent by the electronic tag to the reader Γ „ is: T _u = Ti + random^ ~ N _s , xT _s .

Preferably, when a random number is generated according to the number of time slots included in an inventory period, the high frequency clock can be captured based on a low frequency clock inside the central processing unit to generate a random number. Specifically, determining the number of bits occupied by the random number according to the number of time slots included in an inventory period, and initializing the random number; and determining whether the number of times of the capture reaches the number of bits occupied by the random number, and if the number of bits occupied by the random number is not reached, Move the random number to the left by one bit, start the timer and capture the high frequency clock based on the low frequency clock, take the value of the lowest bit of the captured data as the value of the lowest bit of the random number, and add 1 to the number of captures. It is determined again whether the number of acquisitions reaches the number of bits occupied by the random number; if the number of bits occupied by the random number is reached, the time slot corresponding to the random number is selected to send a message to the reader.

For example, if the number of slots included in an inventory cycle is 7, the number of bits occupied by the random number is 3, and the random number is initialized to zero. When the number of captures is determined to be zero, the random number is shifted to the left by one bit, and the start is performed. The timer captures the high frequency clock based on the low frequency clock. If the lowest bit of the captured data is 1, the lowest bit position of the random number is 1 and the number of captures is increased by 1 (the number of captures is 1); If the number of captures is 1, the random number is shifted to the left by one bit, the timer is started, and the high frequency clock is captured based on the low frequency clock. If the lowest bit of the captured data is 0, the lowest bit position of the random number is 0. , and increase the number of captures by 1 (the number of captures is 2); to determine the number of captures is 2, the random number is shifted to the left by one bit, the timer is started, and the high frequency clock is captured based on the low frequency clock, if the captured data is the lowest If the bit is 1, the lowest bit position of the random number is 1 and the number of captures is increased by 1 (the number of captures is 3); then the number of captures is 3, and the random number is occupied. The number of bits, a random number is generated, and the random number represented in binary as 101, that is 5, the fifth slot from the start to send information to the reader.

Step 303: Send a message to the reader based on the selected time slot.

In practical applications, after generating the random number Random, the waiting time Δ7 is calculated according to the random number; and the timer inside the central processing unit is configured to be Δ7 according to the waiting time; while waiting for Δ71 Long after sending a message to the reader.

Based on the foregoing technical solution, in the embodiment of the present invention, by adding a field in a data frame of the reader, and placing a frame number of the data frame in the added field, the electronic tag transmits the data frame in the current inventory period of the reader. After that, the data frame is parsed and the frame number is extracted from the predetermined field, and then the length of time that the current inventory period enters the channel idle state is calculated based on the extracted frame number, and after waiting for the duration, when the reader is determined to be the channel idle state, the selection is performed. The time slot sends a message to the reader, thereby realizing the two-way communication between the electronic tag and the reader, and does not increase the energy consumption of the battery by the active electronic tag, thereby ensuring the stability of communication between the electronic tag and the reader. . In addition, the technical solution provided by the embodiment of the present invention does not need to change the original hardware structure of the radio frequency communication system, and the implementation is simple. The spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and modifications of the invention

Claims

Claim

A communication method based on a radio frequency identification system, characterized in that it comprises:

Receiving a data frame sent by the reader during the current inventory period;

A message is sent to the reader based on the selected time slot.

2. The method according to claim 1, wherein the receiving reader before the data frame sent in the current inventory period further comprises:

Presetting the format of the data frame sent by the reader, and presetting the frame number of the data frame in a predetermined field in the data frame.

The method according to claim 1, wherein the calculating, based on the extracted frame number, a duration of waiting for the current inventory period to enter the channel idle state, includes:

The time taken to send a single data frame according to the total time of transmission in the current inventory period, and the frame number extracted from the predetermined field of the data frame, to calculate the waiting time for entering the channel idle state.

The method according to claim 1, 2 or 3, wherein, when determining that the reader is in a channel idle state, selecting a time slot from the time slots included in the current inventory period includes: determining a current inventory The number of time slots in the channel idle state in the period, and generates a random number according to the number of time slots, and selects the time slot corresponding to the random number.

The method according to claim 4, wherein when the random number is generated according to the number of time slots, the method includes:

Determining, according to the number of time slots, the number of bits occupied by the random number, and initializing the random number; determining whether the number of times of capturing reaches the number of bits occupied by the random number, and if the number of bits occupied by the random number is not reached, shifting the random number to the left by one bit Bit, start timer and based on low frequency clock to high frequency The clock is captured, and the value of the lowest bit of the captured data is used as the value of the lowest bit of the random number, and the number of times of capture is incremented by one to determine whether the number of times of capture reaches the number of bits occupied by the random number;

If the number of bits occupied by the random number is reached, the time slot corresponding to the random number is selected.

6. A communication device based on a radio frequency identification system, comprising:

7. The apparatus according to claim 6, wherein the format of the data frame sent by the reader is preset in the data frame before the radio frequency chip receives the data frame sent by the reader in the current inventory period. The frame number of the data frame is preset in a predetermined field.

The device according to claim 6, wherein the central processor calculates, according to the extracted frame number, a duration that the current inventory period has to wait for entering the channel idle state, specifically: according to the total number of transmissions occupied in the current inventory period Time, the time taken to transmit a single data frame, and the frame number extracted from the predetermined field of the data frame, to calculate the time to wait for entering the channel idle state.

The device according to claim 6, 7 or 8, wherein the central processor selects a time slot from the time slots included in the current inventory period when determining that the reader is in the channel idle state, specifically :

Determining the number of time slots in the channel idle state in the current inventory period, and generating a random number according to the number of the time slots, and selecting the time slot corresponding to the random number.

10. The apparatus of claim 9, wherein the central processor is time dependent The number of slots generates a random number, which is specifically:

Determining, according to the number of time slots, the number of bits occupied by the random number, and initializing the random number; determining whether the number of times of capturing reaches the number of bits occupied by the random number, and if the number of bits occupied by the random number is not reached, shifting the random number to the left by one bit Bit, start the timer and capture the high frequency clock based on the low frequency clock, take the value of the lowest bit of the captured data as the value of the lowest bit of the random number, and add 1 to the number of captures to determine whether the number of captures is again The number of bits occupied by the random number is reached;

11. A radio frequency identification based communication system, comprising: