CN106572429B - Bidirectional communication system for logistics tracking - Google Patents

Abstract

The present invention provides a method of operating a two-way communication system between a plurality of communication devices, the communication devices including at least one communication controller and a plurality of nodes, including a first node. The method includes the step of periodically broadcasting a beacon signal from the communications controller, via a channel of the first host, within a broadcast interval, the beacon signal containing a first address of the communications controller. The method also includes: the first node periodically scans the beacon signal of the first host. Upon detecting the beacon signal, the first node sends an identification payload to the communications controller. Upon receipt of the identification payload, the communications controller sends an acknowledgement signal to the first node.

Description

Two-way communication system for logistics tracking

【Technical field】

The present invention relates to a logistics management method using a two-way wireless communication system, and in particular to a method for monitoring the location of goods based on active RFID technology using low-power RFID tags and a handshake communication protocol.

【Background technique】

The traditional logistics tracking system based on RFID technology can be implemented by active RFID tags or passive RFID tags. Known active RFID tags have their own power source and transmitter, enabling the tag to broadcast a signal. Compared with passive RFID tags, the performance of active RFID tags includes wider read range and stronger storage capacity. However, for greater read range and storage capabilities, higher power requirements are required. Typically, active RFID tags are powered by long-life batteries that can last for years, but eventually need to be replaced.

Two different types of active RFID tags are known, transponders and beacons. Active RFID transponders only communicate when there is an interrogation signal from a reader, so when the tag is out of range of the reader, it saves power and helps prolong battery life. Active RFID transponders are commonly used for security access control and toll booth payment systems.

Beacons used as active RFID tags transmit identification information periodically at user-set intervals, while an RFID reader captures the signal through an antenna and uses back-end software to determine the tag's location. Active RFID tags of this type are commonly used in real-time location systems (RTLS), which are common in outdoor transportation yards and throughout the supply chain. Some active RFID tags can achieve a read range of 100 meters in ideal outdoor environments.

All these extra features will lead to an increase in cost. The price of an active RFID tag depends on the tag's ability to withstand harsh conditions and other important functions of the tag.

Bluetooth Low Energy (BLE) technology is a known wireless system suitable for active RFID applications. iBeacon is a BLE-based protocol developed by Apple, and many vendors make iBeacon-compatible hardware transmitters, which are commonly referred to as beacons, a BLE device that broadcasts its identification code to nearby portable electronic devices. iBeacon technology enables smartphones, tablets and other devices to perform certain actions when they are near an iBeacon tag. Once an iBeacon tag is detected, the mobile phone uses the received iBeacon information and location information to activate the associated mobile application based on a contextual search. In this example, different iBeacon tags can activate different mobile applications in order to provide promotional or advertising campaign information to users using mobile phones.

iBeacon uses BLE's proximity sensor technology to broadcast a universally unique identification code that is captured by a reader with a compatible app or operating system. The identifier and data sent with it can be used to determine the physical location of the device, customer tracking, or to trigger a location-based action on the device, such as a social media check-in, or push notifications.

However, some hurdles need to be overcome if BLE's iBeacon is to be used for active RFID applications. Some limitations of current iBeacon solutions for active RFID applications are:

1. The BLE standard provides 40 channels. Only three of these broadcast channels (37, 38 and 39) can be used for iBeacon applications. In the case of no signal collision, a maximum of 400 time slots can be generated (100ms broadcast interval according to iBeacon, and about 0.75ms advertising packet time, ie (100/0.75)×3 broadcast channels). For applications where the tag reader needs to read potentially thousands of active RFID tags, the iBeacon solution using BLE is not feasible because the probability of signal collision increases with the number of iBeacon tags.

2. The iBeacon solution will continue to broadcast regardless of whether there is a tag reader. This will result in wasted battery power, shorten battery life, and increase the replacement rate of active RFID tags, thereby increasing the cost of use. In addition, under the FAA regulations, it is required to prohibit the transmission of RF signals by equipment on the aircraft in flight, so RFID using this broadcast scheme will not be allowed to be applied on the aircraft.

3. The iBeacon solution does not have reliable data interaction between tags and readers. A tag using the iBeacon scheme does not know whether the tag reader has successfully acquired its data because the reader does not send a reply to the tag. Therefore the tag has to continuously broadcast its data periodically.

4. The iBeacon scheme has no data security, because any BLE device can sniff and hear the data broadcast by the tag.

Therefore, for active RFID applications, it is necessary to use BLE technology in an enhanced way to take advantage of its low cost and low power consumption while overcoming the shortcomings of traditional iBeacon solutions.

Furthermore, it would be preferable if the tag reader could read an unlimited number of tags within its coverage. It would be better if the tag reader could quickly and reliably extract the identification payload from the tag. It would be even better if the battery life of the tag could be extended to last for many years.

The present invention will satisfy these needs.

【Summary of Invention】

The invention is characterized by the characterizing parts of the independent claims. Other embodiments of the invention are also described in the independent claims.

According to a first aspect of the present invention, there is provided a method of operating a two-way communication system between a plurality of communication devices, the two-way communication system comprising at least one communication controller and a plurality of nodes including a first node. The method includes: periodically broadcasting a beacon signal from the communication controller via a channel of the first host within a broadcast interval; the beacon signal includes the first address of the communication controller. The method further includes: the first node periodically scans the beacon signal of the first host, and once the first node detects the beacon signal, the first node sends an identification payload To the communications controller, once the communications controller receives the identification payload, it sends an acknowledgement signal to the first node.

According to a preferred embodiment, the reply signal further contains instructions instructing the first node to perform at least one subsequent operation. One of the subsequent operations is that the first node enters a sleep mode for a specified period of time. Another of the subsequent operations is that the first node is shut down.

According to a preferred embodiment, after receiving the response signal, the first node enters a sleep mode for a first sleep time.

According to a preferred embodiment, after the first node sends the identification payload, if the first node does not receive the response signal within a predetermined time, the first node enters a sleep mode and lasts for the second sleep mode time. In particular, the first sleep duration is longer than the second sleep duration.

According to a preferred embodiment, the communication controller periodically broadcasts the beacon signal in multiple time slots via other channels with different broadcast frequencies on the first host within the same broadcast interval.

According to a preferred embodiment, the communication controller periodically broadcasts at least another beacon signal on a channel of the second host at the same broadcast interval, which includes at least another beacon signal of the communication controller. an address. The broadcast frequency of the same channel in different hosts is the same. According to yet another preferred embodiment, the communication controller includes at least two hosts, and each host periodically broadcasts three beacon signals; each host contains different addresses of the communication controller, and the same channel on different hosts The broadcast frequency is the same.

According to a preferred embodiment, the communication controller includes 8 hosts, and for a broadcast channel, the communication controller broadcasts the beacon signals of the 8 hosts using different time slots, and the total broadcast time is equal to or less than 30% of the broadcast interval.

According to a preferred embodiment, within one broadcast period, a beacon signal of the first host is followed immediately by a beacon signal of the second host having the same broadcast frequency within one broadcast period .

According to a preferred embodiment, the beacon signal of the first host and the beacon signal of the second host having the same frequency are separated by a preset time interval.

According to a preferred embodiment, the communication controller includes 16 hosts. For one broadcast channel, the beacon signals of the 16 hosts are broadcast by the communication controller using different time slots, and the total broadcast time is equal to or less than 60% of the broadcast interval.

According to a preferred embodiment, once the first node detects the beacon signal and only detects that the beacon signal appears on the same channel within the next broadcast interval, the first node sends the identification payload to all the communication controller.

According to a preferred embodiment, when the signal strength of the beacon signal received by the first node is low, the first node will immediately connect to the address of the communication controller to which it received the beacon signal. Otherwise, the first node will be connected to an alternate address of the communication controller.

According to a preferred embodiment, the communication controller is a tag reader and the plurality of nodes are tags. In particular, the two-way communication system is a Bluetooth Low Energy system. The beacon signal is set to a limited discovery mode.

According to a second aspect of the present invention, there is provided a two-way communication system for logistics tracking. The communication system includes at least one communication controller and a plurality of nodes, including a first node. The communication controller periodically broadcasts a beacon signal according to a fixed broadcast interval via a channel of the first host. The beacon signal includes a first address of the communications controller. The first node periodically scans for the beacon signal of the at least one host. The first node sends an identification payload of the first node to the communication controller upon detecting the beacon signal. The communications controller sends an acknowledgement signal to the first node upon receipt of the identification payload.

According to a third aspect of the present invention, there is provided a two-way communication system for logistics tracking, comprising at least one communication controller and a plurality of inventory-related nodes, including a first node; the communication controller via a first host computer a channel that periodically broadcasts a beacon signal according to a fixed broadcast interval, the beacon signal containing the first address of the communication controller; wherein the first node periodically scans the first host beacon signal on; wherein once the first node detects the beacon signal, it sends the identification payload of the first node to the communication controller; once the communication controller receives the identification payload, send an acknowledgement signal to the first node.

In particular, the two-way communication system for logistics tracking further includes a local server for collecting and recording the presence information of the plurality of nodes from the communication controller.

In particular, the two-way communication system for logistics tracking further includes a remote server for collecting and recording the presence information of the plurality of nodes from the communication controller.

According to a fourth aspect of the present invention, there is provided a data network for logistics tracking, comprising at least one communication controller and a plurality of inventory-related nodes, including a first node; the communication controller via a first host computer A channel that periodically broadcasts a beacon signal according to a fixed broadcast interval, and the beacon signal contains the first address of the communication controller; wherein the first node periodically scans the first node for a beacon signal; wherein upon detecting the beacon signal, the first node sends an identification payload of the first node to the communication controller; wherein upon receiving the identification payload, the communication controller, A reply signal is sent to the first node.

According to a fifth aspect of the present invention, there is provided a communication controller in a data network, the data network further comprising a plurality of nodes including a first node, the communication controller comprising: a processor, a the memory of the processor, and an interface controlled by the processor: the communication controller periodically broadcasts a beacon signal at a fixed broadcast interval via a channel of the first host, the beacon The signal contains the first address of the communications controller, and upon receipt of the identification payload from the first node, an acknowledgement signal is sent to the first node.

According to a sixth aspect of the present invention, there is provided a first node in a data network, the data network further comprising a communication controller and a plurality of nodes including the first node. The first node includes: a processor, a memory providing code to the processor, and an interface controlled by the processor: the first node periodically scans for a first host controlled by the communication controller The broadcast beacon signal, and after detecting the beacon signal, an identification payload is sent to the communication controller, and the first node enters the sleep mode after receiving the response signal, and continues for the third During a sleep time, if the first node fails to receive a response signal within a preset time after sending the identification payload, it enters the sleep mode and lasts for the second sleep time.

【Description of drawings】

Specific embodiments of the present invention will now be described with reference to the following drawings.

FIG. 1 is a schematic diagram of a system according to an embodiment of the present invention.

FIG. 2 is a schematic block diagram of a tag reader according to an embodiment of the present invention.

FIG. 3 is a schematic block diagram of a tag according to an embodiment of the present invention.

Figure 4 is a message flow diagram between a tag reader and a tag according to one embodiment of the present invention.

Figure 5a is a signal schematic diagram of broadcast beacon duration and interval for a tag reader with multiple hosts according to one embodiment of the present invention.

Figure 5b is a signal schematic diagram of broadcast beacon duration and interval of a tag reader with multiple hosts according to another embodiment of the present invention.

FIG. 6 is a signal schematic diagram of a tag scanning window for detecting a broadcast advertisement beacon in a scanning phase according to an embodiment of the present invention.

FIG. 7 is a timeline of a tag wake-up period during a scan phase according to one embodiment of the present invention.

FIG. 8 is a flowchart of the steps performed by the tag in the connection phase according to an embodiment of the present invention.

FIG. 9 is a schematic diagram of the application of a logistics system according to an embodiment of the present invention.

[Detailed description of the invention]

The present invention provides an improved logistics tracking method. Although various embodiments of the present invention have been described below, the present invention is not limited to these embodiments, and variations of these embodiments are intended to fall within the scope of the present invention, which is limited by the claims.

The present invention can be applied in conjunction with any wireless communication system, such as Bluetooth Low Energy (BLE), Bluetooth, ANT, ANT+, ZigBee, Wi-Fi, and Near Field Communication (NFC) standards, among others.

According to one embodiment of the present invention, BLE technology is used in an enhanced manner for active RFID applications, thereby taking advantage of its low cost and low power consumption, while overcoming the shortcomings of the traditional iBeacon approach.

A standard Bluetooth low energy application for reading broadcast information uses the iBeacon scheme to broadcast information to smartphones, tablets and other devices. However, the Bluetooth Low Energy standard has only 3 broadcast channels. In active RFID applications, since the iBeacon scheme can only provide up to 400 broadcast time slots (according to the iBeacon broadcast interval of 100 milliseconds and the iBeacon packet transmission time of 0.75 milliseconds), it cannot be used. Although there are theoretically a maximum of 400 broadcast time slots, since channel collisions may occur when there are a very large number of tags (such as thousands) in the coverage area, the success rate of obtaining a complete broadcast beacon will be greatly increased. reduce. In addition to this, the iBeacon method is also unreliable because it lacks an acknowledgement signal after data is received. Also, since the iBeacon scheme adopts the method of continuous broadcasting, the battery life of the tags cannot be optimized, and the conflict problem still exists when a large number of tags are gathered together. Moreover, under the FAA regulations, it is required to prohibit the transmission of RF signals from the equipment on the aircraft in flight, so RFID using this broadcast scheme will not be allowed to be applied on the aircraft.

FIG. 1 depicts a logistics tracking system 100 according to one embodiment of the present invention. The logistics tracking system 100 includes a communication controller, such as a tag reader 110, and a plurality of nodes, such as tags 120, 121, 122, and the like. Tags 120 , 121 and 122 are self powered and periodically wake up from sleep mode to detect the presence of tag reader 110 , establish wireless communication, and send identification data to tag reader 110 . Tag reader 110 records identification data received from tags 120, 121 and 122 and transmits the data to other readers or a central monitoring station via a network (not shown). This data can be used to monitor the location of objects associated with tags 120, 121, and 122, and can also be used to generate messages showing object location information. The data transfer between the tags 120, 121, 122 and the tag reader 110 takes place in a reliable and secure manner. According to one embodiment of the present invention, BLE topology technology is used to support the reading of a large number of tags within a spatial coverage area with a radius of up to 50 meters centered on the tag reader 110 .

FIG. 2 depicts a schematic diagram of hardware modules of a tag reader 200 according to an embodiment of the present invention. Tag reader 200 includes a processor 210 having operating system and control software, processor 210 communicates with BLE beacon communicator 220 to establish wireless communication with tags (not shown), tag reader 200 Also includes cellular data adapter 230 and WLAN module 240

FIG. 3 depicts a schematic diagram of hardware modules of a tag 300 according to an embodiment of the present invention. Tag 300 includes a controller 310 that communicates with BLE communicator 320 . Through the BLE communicator 320, the tag 300 can establish wireless communication with a tag reader (not shown in the figure), thereby being able to scan for beacon signals, send identification signals, and receive response signals and instructions, etc. The controller 310 controls the operation of the tag 300 in different modes, such as scan mode, connection mode and sleep mode. The functions of the controller 310 may be implemented by hardware logic or software executed by a processor.

FIG. 4 shows a message flow diagram between tag reader 410 and tag 420 according to one embodiment of the present invention. The tag reader 410 broadcasts the beacon signal 401 as a broadcaster on the advertising channel of a BLE host. As defined by the BLE standard, a BLE host contains 3 broadcast channels, namely channels 37, 38 and 39. If the broadcast interval is set to 20ms, then a maximum of 3 beacons can be sent every 20ms, which means that each BLE host broadcasts a total of 150 beacons per second. The broadcast protocol and broadcast state timing are explained in detail in the Bluetooth Technical Manual Specification v4.0 Volume 6, Section 4.4.2. On the other hand, the tag 420 wakes up periodically and detects the presence of the beacon signal 401 from the beacon reader 410 within a scan interval. The scan interval (wake-up time) depends on how quickly the tag 420 is detected by the tag reader 410, and the expected battery life of the tag 420.

Once the beacon signal is detected by the tag 420, the tag 420 initiates a connection with the tag reader 410, sending its identification payload 402 to the tag reader 410. In response to receipt of the identification payload, the tag reader 410 will transmit an acknowledgement packet 403 to the tag 420 to acknowledge receipt. The channel configuration during the broadcast process and connection setup process will be further described below.

According to one embodiment of the present invention, BLE channels 37, 38 and 39 are allocated for broadcast and connection setup purposes. Specifically, in BLE Limited Discoverable Mode (BLE Limited Discoverable Mode), by setting the "limited flag" on the connectable message packet, the BLE limited discovery mode can be used, so that channels 37, 38 and 39 can be used in the broadcast phase and The connection setup phase runs. The limited discovery mode on the GAP layer is discussed in detail in the Bluetooth Technical Manual Specification v4.0 Volume 3 Section 9.2.3.

During the broadcast phase, channels 37, 38, 39 are set as broadcast channels, allowing only downlink communication. Tag reader 410 transmits connectable message packets on channels 37 , 38 , 39 . During the connection setup phase, the channels 37, 38, 39 are set up to support bidirectional communication.

On the tag side, a limited discovery process is used to find any nearby tag readers 410 operating in limited discovery mode. When a tag reader 410 is found, the tag 420 attempts to connect with it. According to the BLE standard, the connection setup process is carried out through these 3 broadcast channels 37, 38, 39. After completing the connection, tag reader 410 and tag 420 will exchange data (eg, identification payloads) on one of the 37 data channels (0-36) available as defined by the BLE standard. The connection setup process is discussed in detail in the Bluetooth Technical Manual Specification v4.0, Volume 6, Section 4.4.4 (Startup State and Connection State).

After connection setup, all data transfers (eg, identification payloads) on data channels (0-36) will be established according to the GATT configuration on the L2CAP connection. The connection can be encrypted for enhanced security. The communication protocol after connection setup is discussed in detail in the Bluetooth Technical Manual Specification v4.0 Volume 3 Part F Attribute Protocol (ATT) and Part G Generic Attribute Configuration (GATT).

According to another embodiment of the present invention, the response packet 403 also includes a control byte that allows the tag reader to instruct the tag 420 to perform subsequent actions. For example, to optimize tag power consumption, the control byte may indicate a preset sleep duration before the tag 420 will wake up to detect broadcast beacons again. In another example, the control byte may instruct the tag to shut down.

According to one embodiment of the invention, the tag reader may be powered by AC power, in which case power consumption considerations are less important. Figure 5a is a signal schematic diagram of broadcast beacon duration and interval time of a tag reader having multiple hosts 510, 520, etc., according to one embodiment of the present invention. The BLE beacon communicator on the tag reader consists of a set of 8 independent BLE host modules, the 3 LSB bits in the Bluetooth address of these BLE host modules are different and fixed to 0-7 (see Figure 1 and Figure 1). 2). Each channel of the BLE host module (eg 510) independently broadcasts a unique beacon ID (eg 511) within the minimum interval of 20 milliseconds defined by the BLE standard. The same broadcast channel on different hosts has the same frequency. For example, the channel 37 of the first host 510 and the channel 37 of the second host 520 have the same frequency. It is better not to overlap the beacons of different hosts on the same advertising channel in the time domain to avoid mutual interference. Based on 3 beacons (511, 512, 513) every 20 ms per BLE host, there can be 150 beacons broadcast per second per BLE host. With 8 BLE hosts, there are a total of 1200 beacon broadcasts per second in the tag reader. Thus, the chances of a tag successfully connecting to one of the eight BLE host channels available on the tag reader can be greatly improved. The ratio of the number of tag readers with 8 independent BLE hosts to the number of tags being scanned depends on the detection time required when the maximum number of tags is present within the range of the tag reader.

According to an embodiment of the present invention, the duration of the beacon packet is about 750 microseconds, and the broadcast interval is set to 20 milliseconds, so a maximum of 20/0.75×3=80 broadcast channels can be provided, that is, 80 BLE channels can be used theoretically Broadcast time slot. However, due to the possibility of collisions between beacons using the same time slot, it is best to limit the number of tags within the coverage area. In the case of only one tag reader (with 8 hosts), for each broadcast channel, 8x3/80=30% of the broadcast time slots are utilized. When the number of tag readers in the coverage increases, the broadcast interval can be increased to more than 20 milliseconds, so that the utilization of the broadcast slot remains at 30% or less for each broadcast channel, This keeps the beacon collision probability at a reasonably low level, thereby achieving an optimal balance between high tag read rates and low beacon collision rates.

According to another embodiment of the present invention, when a tag reader has 16 BLE hosts, the broadcast slot utilization rate of each broadcast channel can be as high as 60% without causing obvious beacon collision problems. Setting the broadcast interval of each host to 20 ms as the optimal configuration can keep the beacon collision probability at a reasonably low level, thus achieving the best balance between high tag read rate and low beacon collision rate.

For most typical use cases, when a tag reader has 8 hosts, each host's broadcast interval is set to 20ms to achieve 30% broadcast slot utilization (for each broadcast channel) , it is enough to get a reasonable read rate. On the other hand, 60% broadcast slot utilization (for each broadcast channel) of 16 hosts is the best implementation for scenarios that require detection of a relatively large number of tags at the fastest read rate.

According to one embodiment of the present invention, the beacon order of the same channel on different host modules is correlated in the time domain, so that one host module 510 is on channel 37 (at the first broadcast frequency) within one broadcast cycle time. The first beacon 511 on is followed by a first beacon 514 on channel 37 (the same first broadcast frequency) by another host module 520 within one broadcast period. In other words, beacons on the same broadcast channel from different hosts will follow one after the other.

FIG. 5b is a signal schematic diagram of broadcast beacon duration and time interval of a tag reader with multiple hosts 510, 520, etc., according to another embodiment of the present invention. The order of beacons for the same channel on different host modules is correlated in the time domain such that the first beacon 515 of one host module 510 on channel 37 (the first broadcast frequency) is on channel with another host module 520. 37 (same first broadcast frequency) between the first beacons 516, separated by a preset time. In other words, beacons on the same broadcast channel of different hosts are separated by a preset time.

FIG. 6 shows a signal schematic diagram of a tag scanning window for detecting broadcast beacons in a scanning phase according to an embodiment of the present invention. The beacon detection rate depends on the scan interval period 610 of the tag and the scan window duration 620 . Setting different scan window durations 620 changes the probability that the tag will detect a beacon. A longer scan window time ensures that beacons are detected earlier, while a shorter scan window time increases the chance of undetected beacons, because tags may appear at a time when no beacons are present. scan in the window. On the other hand, a longer scan window time has a huge impact on the power consumption of the tag, because power consumption is closely related to the length of time the wireless circuit must be turned on. The scan interval period time 610 and scan window duration 620 parameters determine how often and how often a scanner device (eg, tag) will listen for potential broadcast beacon packets. As with the broadcast interval, these values have a profound impact on power consumption because they are directly related to the length of time the radio must be turned on.

A consideration when designing the system is to save the power consumption of the tag (low duty cycle RF activity), this is because the tag is best to use a small size battery, such as a coin cell battery, for easy installation on the cargo. Power consumption is not an issue for the reader because the reader usually operates in a fixed location and can therefore be connected to an external power source. For this reason, the reader can take on more powerful CPUs and higher duty cycles of RF activity. The tag's scan interval cycle time 610 and scan window duration 620 can be set to optimize its battery life, while increasing the rate of tag detection by adjusting the tag reader's aggressive broadcast interval (up to every 20 milliseconds).

According to one embodiment of the present invention, a beacon broadcast duration is approximately 750 microseconds. The broadcast beacons for channels 37, 38 and 39 are sent continuously. The total broadcast time of these 3 beacons is approximately 750 microseconds x 3 = 2.25 milliseconds. To optimize the battery life of the tag, the tag's scan window duration can be set to 3 milliseconds and scanned with a wake-up cycle of every 2 seconds (i.e., every 2-second scan interval cycle time). Since 3 milliseconds can cover the duration of 3 advertising beacons, the tag has enough chance to detect one of the advertising beacons of one of the tag readers (with 8 BLE hosts).

It is also possible that the scanning window duration of the tag does not coincide with the broadcast beacon slot. In this case the tag will sleep, wake up after 2 seconds to scan for broadcast beacons again. According to the broadcast beacon interval of each BLE host of the tag reader of 20ms, 8 BLE hosts will occupy a slot time of 2.25ms×8=18ms. In particular when there are many tags within range of a tag reader, the probability that a tag with a 3ms scan window duration will detect a beacon from at least one of the tag readers (with 8 BLE hosts) will very high. Once a tag detects a tag reader's broadcast beacon, it considers a tag reader present. The next step for the tag is to progress from the scan phase to the connect phase, which is further described in Figure 8 below.

FIG. 7 is a timing diagram of a tag wake-up period in a scan phase according to an embodiment of the present invention. The tag needs to be able to detect the tag reader's beacon ID in order to initiate a connection to that specific BLE host of the tag reader. At step 701, the tag periodically wakes up to detect the presence of a beacon signal containing a beacon ID. If no beacon signal is detected, the tag proceeds to step 702 and returns to a sleep state until the end of the scan cycle interval. During the scan phase, only the receive circuit of the tag 300 is turned on to detect the beacon ID, while the transmitter of the tag 300 is turned off. This is important to ensure extended tag battery life and open RFID tag applications on an airplane. In the cabin, since there is no tag reader, the tag 300 will not detect the beacon ID, so the tag will go to sleep and the transmitter circuit will not be turned on to send the identification payload throughout the flight. In another embodiment, the tag will not enter a sleep phase, but rather be set to enter a scan phase in which the transmitter circuit is turned off. Since the transmitter circuit of the tag 300 is always off during flight, it complies with FAA regulations and can be used in the cabin. To optimize the battery life of the tag, at least one of the following methods can be implemented.

According to an embodiment of the present invention, by increasing the number of tag readers (that is, increasing the ratio between readers and the number of tags that need to be read), it is possible to ensure that enough BLE hosts can be accessed by tags, and upload a single tag payload to the tag reader. The faster a tag sends its payload, the faster it goes to sleep, extending battery life. More BLE hosts (more tag readers) and fewer connection retries will improve the battery life of the tag.

According to one embodiment of the present invention, the tag reader has 8 hosts, and its broadcast beacon interval period is optimally set to 20 milliseconds multiplied by the number of tag readers to maintain 30% broadcast slot utilization (for each for a broadcast channel).

According to another embodiment of the present invention, the tag reader has 16 hosts, and its broadcast beacon interval period is set to 20 milliseconds multiplied by the number of tag readers to maintain 60% broadcast slot utilization (for each for a broadcast channel).

Setting a longer broadcast interval of broadcast packets can reduce the probability of beacon collision, but it will also reduce the rate at which tags are discovered and connected. This requires a balance between the number of host channels and the advertising interval period for the tag detection rate. According to one embodiment of the present invention, 20 milliseconds is chosen as the shortest broadcast interval period to obtain the fastest possible tag detection rate while the beacon collision probability is at a reasonably low level.

According to another embodiment of the present invention, the battery life of the tag can be optimized by adjusting the wakeup interval period in which the tag periodically scans the tag reader beacon ID. When using a coin cell battery, the optimal value for the wake-up interval period used to scan for beacon IDs is 2 seconds. At step 703, the tag wakes up from sleep mode and starts scanning for beacon IDs. When the tag finds the tag reader, it proceeds to step 704, sends the identification payload, and enters sleep mode. Also the wake-up interval is set to a few minutes so that other tags have more chances to connect with the tag reader. Once the set sleep time expires, the tag will wake up and perform step 705 to scan for broadcast beacons again.

FIG. 8 is a flow chart of the steps performed by the tag in the connection stage according to an embodiment of the present invention. To establish a connection, the tag first starts at step 801 by scanning the tag reader for BLE hosts that have detected beacons. This extra scan step is to ensure that the host is still available and not occupied by other device connections before connecting.

According to one embodiment of the present invention, both the scan window and scan interval period are set to 30ms for a total time of 90ms to allow the tag to complete scanning all 3 broadcast channels of a particular BLE host (steps 803-808). If the beacon is still not detected at the end of 90 milliseconds, the process goes to step 810, and the tag will repeat the scanning process for the remaining 7 of the 8 BLE hosts of the tag reader in a random manner. If a beacon is successfully detected, the tag will proceed to step 809, send a connection request to the BLE host, and then complete sending the payload to the tag reader (step 812). If after trying all 8 hosts of the tag reader, there is still no successful beacon detection (step 811), then the tag will proceed to step 813 to sleep and wake up after 2 seconds to detect broadcast beacons again .

According to an embodiment of the present invention, setting the scanning window and the scanning interval to the same value will enable the BLE tag to continuously scan on the three advertising channels of the same host. At first, the broadcaster (reader) and scanner (tag) may not be on the same channel. This is why 3 broadcast channel time intervals need to be considered when setting the total scan time. According to the BLE technical manual specification, during each broadcast cycle, a random time shift is added to the broadcast packet start time, thereby avoiding continuous collision of broadcast packets between different hosts. According to an embodiment of the present invention, instead of setting 20 milliseconds multiplied by 3 as the total scan time, 30 milliseconds multiplied by 3 is used to meet the time shift requirement. The scan protocol and scan state time are detailed in the Bluetooth Technical Manual Specification v4.0 Volume 6 Section 4.4.3.

According to another embodiment of the present invention, through the control byte in the response packet of the tag reader, the tag can be set to sleep for an adjustable sleep time, or enter a shutdown state. When the tag has successfully sent its identification payload to the tag reader, the tag reader will send an acknowledgement packet containing a control byte to the tag to acknowledge receipt. In the control byte, there are parameters to set the wake-up time of the tag or instruct the tag to shut down. After the tag successfully sends its identification payload, setting the tag to enter a longer wake-up interval will effectively prevent the tag from competing with other tags to access the BLE host of the tag reader. The value of the tag wake-up interval can be determined by the tag reader according to its preset target. Typically, the wake-up time default is at least 5 minutes. To better manage the battery life of the tags, the tag reader can also use the tag ID to determine transit time when the tagged item leaves the storage area and is transported by land, sea or air. The tag reader can use a cellular data network or WiFi to query the central server to determine its current location, and the time of the tagged item is sensed by the tag reader in the next storage area where the tagged item is to be delivered, to determine its current location. Determine the minimum transit time for labeled goods. When the tagged item has reached its final destination, the tag reader instructs the tag to shut down so that no power is consumed during its return to the original tag distribution. In the logistics supply chain, it is estimated that only 15% of the time tags are actively scanned by tag readers. By using a tag reader to control the sleep time and shutdown sequence of the tag, the battery life of a tag running on a coin cell battery can be extended to 4-6 years before battery replacement or tag replacement is required. Therefore, the operating cost of an active RFIDBLE tag system utilizing the present invention is very economical in practical application.

FIG. 9 is a schematic diagram of the application of a logistics system 900 according to an embodiment of the present invention. Depending on the application of the active RFID system, in one embodiment of the invention, the tag 902 can be set to wake up or be turned off at the same/longer interval. In another embodiment of the present invention, the tag 902 may be set to wake continuously when an active RFID tracking system is used to detect dwell time/transfer of tracked goods. When the tag readers 901, 903 are connected to a back-end system 905, the back-end system 905, by collecting this information, can know the travel and schedule of the tagged cargo, such as when the cargo is detected at an airport In the warehouse, when it is moved to the dispatch warehouse for transport to another location. At the shipping station, the tag reader 903 can set the tag 904 to sleep continuously for the duration of the flight or transport to the destination, thereby extending the battery life of the tag.

When the tagged shipment has reached its destination, the tag reader in the arrival area can set the tag off so that the tag can extend battery life, be turned on again after being sent back to the cargo distribution center, and be assigned to another item to track the system.

According to another embodiment of the present invention, the tag will deduce a received signal strength indication (RSSI) based on the received strength of the broadcast packet beacon signal transmitted by the host of the tag reader.

When there are thousands of tags within range of the tag reader, the tags will compete to be able to securely connect to the tag reader's 8 BLE hosts. When the tag scans a beacon of the tag reader, it obtains a Bluetooth address of the specific BLE broadcast channel. By mapping the corresponding Bluetooth address, the remaining BLE broadcast channels on the tag reader can be inferred. . Along with the RSSI data information of the detected beacon, the tag can determine whether the tag reader is moving away or approaching.

More specifically, the tag reader's RSSI value and the Bluetooth LSB fixed address can be used to enable the tag to perform random tag reader channel connection, so as to effectively utilize the BLE channels of the tag reader's eight BLE hosts. When a large number of tags are within range of a tag reader, there is a high chance that multiple tags will detect the same beacon of a particular BLE host, especially when some BLE hosts have a stronger RF transmitter than others. Time. If multiple tags try to connect to the same BLE host, it is likely that most tags will fail, and the attempts will be repeated. This will result in channel hogging, and multiple retries will reduce the battery life of the tag. To reduce this "channel occupancy" behavior, the tag will use the Bluetooth address pre-assigned to the tag reader (the LSB of the BLE host, which is fixed to 0-7), to deduce the available 8 based on the Bluetooth address of the currently broadcasting beacon BLE host and try to connect. The tag can also determine whether the tag reader is far away or close to the tag based on the RSSI value of the detected beacon.

Using the RSSI and Bluetooth address information of the detected beacons, the tag can choose between two methods of securely connecting to the tag reader. If the RSSI value is good, it means that the distance between the tag and the reader is very close. At this time, the tag can use the random channel connection method, and use any one of the 8 Bluetooth addresses of the tag reader to connect randomly, thereby reducing the channel occupation (the tag tries to connect to the same host). In particular, the tag will first connect using the currently detected BLE host. If the connection is unsuccessful, a different BLE host will be selected for retry according to the random hash algorithm. This process continues until all 8 BLE hosts have been tried, or the tag's identification payload has been successfully sent to the tag reader. In this way, tags competing with each other for the same channel connection can be avoided, thereby increasing the success rate of connecting tag readers.

On the other hand, if the RSSI value of the detected beacon is not good, it means that the tag may not be able to connect to other hosts. At this time, the tag will only use the currently detected BLE host to set up the connection without retrying the other 7 BLE hosts. to connect. This avoids shortening battery life by trying to connect to other BLE hosts that may not be connected.

Although the present invention has been described in conjunction with different embodiments, it should be understood that the present invention is not limited to these embodiments, and is also applicable to those skilled in the art to make substitutions to these embodiments without departing from the scope of the present invention, Improvements and changes. For example, a tag reader can be implemented by software, by setting the cell phone or processor to execute the software.

Claims (23)

1. A method of operation of a two-way communication system between a plurality of communication devices, the communication devices including at least one communication controller (410) and a plurality of nodes, including a first node (420), the method comprising:

periodically broadcasting (401) a beacon signal (511) from said communications controller (410) over a broadcast interval via a channel of a first host (510), said beacon signal (511) including a first address of said communications controller (410);

the first node (420) periodically scanning for the beacon signal (511) broadcast on the first host (510);

-transmitting an identification payload (402) from said first node (420) to said communications controller (410) upon detection of said beacon signal (511) by said first node (420); and

-sending a reply signal (403) to said first node (420) upon receipt of said identification payload by said communication controller (410);

wherein the communication controller (410) periodically broadcasts at least one further beacon signal on a channel of a second host (520) containing at least one further address of the communication controller (410) within the same broadcast interval time, wherein the broadcast frequency of the same channel on different hosts (510, 520) is the same.

2. A method of operating a two-way communication system according to claim 1, wherein the communication controller (410) broadcasts the beacon signal periodically in a plurality of time slots via other channels (512, 513) of different broadcast frequencies on the first host (510) during the same broadcast interval.

3. A method of operating a two-way communication system according to claim 1, wherein a beacon signal (511) of the first host (510) within a broadcast cycle time is followed by a beacon signal (514) of the second host (520) on the same broadcast frequency within a broadcast cycle time;

wherein the beacon signal (515) of the first host (510) and the beacon signal (516) of the second host (520) having the same broadcast frequency are separated by a predetermined time interval.

4. A method of operating a two-way communication system according to claim 3, wherein the communication controller (410) comprises at least 2 hosts (510, 520), each of the hosts (510, 520) periodically broadcasting 3 beacon signals, wherein the hosts (510, 520) contain different addresses of the communication controller (410), the broadcast frequency of the same channel on different hosts (510, 520) being the same.

5. A method of operating a two-way communication system according to claim 3, wherein the communication controller (410) comprises 8 hosts, and for one broadcast channel, the beacon signals of the 8 hosts are broadcast by the communication controller (410) using different time slots, the total broadcast time being equal to or less than 30% of the separation time.

6. Method of operating a two-way communication system according to claim 1, wherein the identification payload (402) is transmitted to the communication controller (410) after the first node (420) has detected the beacon signal (511) and only after it has again detected the presence of the beacon signal on the same channel within the next broadcast time interval.

7. A method of operating a two-way communication system according to claim 3, wherein the first node (420) will connect immediately to the address of the communication controller from which it received a beacon signal when the signal strength of the beacon signal (511) received by the first node (420) is low, otherwise the first node (420) connects to an alternative address of the communication controller.

8. The method of operation of a two-way communication system according to claim 1, wherein the communication controller is a tag reader, the plurality of nodes are tags;

wherein the two-way communication system is a Bluetooth Low energy system;

wherein the beacon signal (511) is set to a limited discovery mode.

9. A two-way communication system for logistics tracking, comprising:

at least one communication controller; and

a plurality of inventory-related nodes, including a first node;

wherein the communications controller periodically broadcasts a beacon signal during a broadcast time interval via a channel of a first host, wherein the beacon signal contains a first address of the communications controller;

wherein the first node periodically scans for the beacon signal on the first host;

wherein the first node transmits an identification payload of the first node to the communications controller upon detecting the beacon signal; and

wherein said communications controller, upon receipt of said identification payload, sends an acknowledgement signal to said first node;

wherein the communications controller periodically broadcasts at least one further beacon signal on a channel of the second host containing at least one further address of the communications controller during the same broadcast interval, wherein the broadcast frequency of the same channel on different hosts is the same.

10. A two-way communication system according to claim 9, wherein the communication controller periodically broadcasts the beacon signal in a plurality of time slots via other channels of different broadcast frequencies on the first host during the same broadcast interval.

11. A two-way communication system according to claim 9, wherein a beacon signal by the first host during a broadcast cycle time is immediately followed by a beacon signal by the second host at the same broadcast frequency during a broadcast cycle time;

wherein the beacon signal of the first host and the beacon signal of the second host having the same broadcast frequency are separated by a predetermined time interval.

12. A two-way communication system according to claim 10, wherein the communication controller comprises at least 2 hosts, each of which periodically broadcasts 3 beacon signals, wherein the hosts contain different addresses of the communication controller, the broadcast frequency of the same channel on different hosts being the same.

13. The two-way communication system of claim 10, wherein the communication controller contains 8 hosts whose beacon signals are broadcast by the communication controller using different time slots for one broadcast channel, the total broadcast time being equal to or less than 30% of the interval time.

14. The two-way communication system of claim 10, further comprising a local server or a remote server for collecting and recording presence information of the plurality of nodes from the communication controller.

15. A communication controller comprising

A processor;

a memory for providing code to said processor; and

a beacon communicator controlled by said processor, said beacon communicator including at least one host for:

periodically broadcasting a beacon signal at a broadcast interval via a channel of a first host, said beacon signal including a first address of said communications controller;

sending a reply signal to the first node upon receipt of the identification payload from the first node;

wherein the communications controller periodically broadcasts at least one further beacon signal on a channel of the second host containing at least one further address of the communications controller during the same broadcast interval, wherein the broadcast frequency of the same channel on different hosts is the same.

16. The communications controller of claim 15, wherein the beacon signal is broadcast periodically in a plurality of time slots during the same broadcast interval time via other channels of different broadcast frequencies on the first host.

17. The communications controller of claim 15, wherein a beacon signal of the first host in a broadcast period is immediately followed by a beacon signal of the second host at the same broadcast frequency in a broadcast period time;

wherein the beacon signal of the first host and the beacon signal of the same broadcast frequency on the second host are separated by a predetermined time interval.

18. The communications controller of claim 15, wherein the communications controller comprises at least 2 hosts, each of which periodically broadcasts 3 beacon signals, wherein the hosts contain different addresses for the communications controller, the broadcast frequencies of the same channel on different hosts being the same.

19. The communications controller of claim 15, wherein said communications controller comprises 8 hosts, each host being assigned a different address; for one broadcast channel, the beacon signals of the 8 hosts are broadcast by the communications controller using different time slots, with a total broadcast time equal to or less than 30% of the interval time.

20. The communications controller of claim 15, wherein the communications controller is a tag reader.

21. A first node comprising:

a processor;

a memory for providing code to said processor; and

a communicator controlled by the processor to:

periodically scanning for a beacon signal broadcast by a first host of a communication controller, the beacon signal including a first address of the communication controller; and

transmitting an identification payload to said communications controller upon detection of said beacon signal;

wherein when the signal strength of the beacon signal received by the first node is low, the first node will immediately connect to the address of the communications controller to which it received the beacon signal, otherwise the first node will be connected to an alternate address of the communications controller.

22. A first node according to claim 21, wherein the identification payload is transmitted to the communications controller after the first node detects the beacon signal and only after detecting again that the beacon signal is present on the same channel within the next broadcast time interval.

23. The first node of claim 21, wherein the first node is a tag.

Images