CN106572429B

CN106572429B - Bidirectional communication system for logistics tracking

Info

Publication number: CN106572429B
Application number: CN201610878739.1A
Authority: CN
Inventors: 黄成达; 庄辉翔; 姜新; 苏升
Original assignee: Ospicon Co ltd
Current assignee: Aokang Co Ltd
Priority date: 2016-10-08
Filing date: 2016-10-08
Publication date: 2022-05-17
Anticipated expiration: 2036-10-08
Also published as: CN106572429A

Abstract

The present invention provides a method of operating a two-way communication system between a plurality of communication devices, the communication devices comprising at least one communication controller and a plurality of nodes, including a first node. The method comprises the following steps: periodically broadcasting a beacon signal from the communications controller via a channel of the first host during a broadcast interval, the beacon signal including a first address of the communications controller. The method further comprises the following steps: the first node periodically scans for beacon signals of the first host. The first node, upon detecting the beacon signal, transmits an identification payload to the communications controller. The communications controller, upon receiving the identification payload, sends a reply signal to the first node.

Description

Bidirectional communication system for logistics tracking

[ technical field ] A method for producing a semiconductor device

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

[ background of the invention ]

Conventional logistics tracking systems based on RFID technology may be implemented by active RFID tags or passive RFID tags. Known active RFID tags have their own power source and transmitter so that the tag can broadcast a signal. The performance of active RFID tags includes a wider read range and greater storage capacity than passive RFID tags. However, in order to obtain a more powerful read range and storage capability, higher power supply power requirements are required. Typically, active RFID tags are powered by long-life batteries, which can last for years, but eventually require battery replacement.

Two different types of active RFID tags are known, which are transponders (transponders) and beacons (beacons). Active RFID transponders communicate only when an interrogation signal from a reader is present, so that power can be conserved when tags are out of reader coverage, contributing to extended battery life. Active RFID transponders are commonly used in security docking controls and toll booth payment systems.

The beacon, which is an active RFID tag, periodically transmits identification information at user-defined intervals, and the RFID reader captures the signal via an antenna and determines the location of the tag using back-end software. 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 reach a read range of 100 meters in an ideal outdoor environment.

All of these additional functions will result in increased costs. The price of an active RFID tag depends on the ability of the tag 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 have made iBeacon-compliant hardware transmitters, commonly referred to as beacons, a BLE device that broadcasts its identification code to nearby portable electronic devices. iBeacon technology enables smart phones, tablets, and other devices to perform certain operations when they are in proximity to an iBeacon tag. Upon detecting the iBeacon tag, the mobile phone may activate the relevant mobile application according to a contextual search (contextual search) using the received iBeacon information and location information. In this example, different iBeacon tags can activate different mobile applications 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 will be captured by a reader with a compatible application or operating system. The identification code and data sent therewith may be used to determine the physical location of the device, customer tracking, or trigger a location-based operation on the device, such as checking in to a social media, or pushing a notification.

However, if BLE iBeacon is used for active RFID applications, some obstacles need to be overcome. Some limitations of the iBeacon scheme currently used for active RFID applications are:

1. the BLE standard provides 40 frequency channels. Of which only three broadcast channels (37, 38 and 39) can be used for iBeacon applications. Without signal collision, a maximum of 400 slots can be generated (according to the iBeacon broadcast interval 100ms, and an advertisement packet time of about 0.75 ms, i.e., (100/0.75) × 3 broadcast channels). For applications where tag readers are to read potentially thousands of active RFID tags, the iBeacon scheme using BLE is not feasible because the probability of signal collisions increases as the number of iBeacon tags increases.

2. The iBeacon scheme continues to broadcast regardless of the presence of a tag reader. This results in wasted battery power, shortened battery life, and increased replacement rates of active RFID tags, thereby increasing use costs. Furthermore, under FAA regulations, it is required to prohibit RF signal transmission from devices on an airplane in flight, and therefore RFID using this broadcasting scheme will not be allowed to be applied on an airplane.

3. The iBeacon scheme does not have reliable data interaction between the tag and the reader. Tags using the iBeacon scheme do not know whether the tag reader has successfully acquired its data because the reader will not send a reply to the tag. The tag has to continuously broadcast its data periodically.

4. The iBeacon scheme has no data security as any BLE device is able to sniff (sniff) and hear the data broadcast by the tag.

Therefore, for active RFID applications, it is necessary to use BLE technology in an enhanced manner to take advantage of its low cost and low power consumption, while overcoming the disadvantages of the conventional iBeacon scheme.

Furthermore, it would be preferable if the tag reader could read an unlimited number of tags within its coverage. It would be advantageous if a tag reader could quickly and reliably extract an identification payload (identification payload) from a 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 address these needs.

[ SUMMARY OF THE INVENTION ]

The invention is characterized by the characterizing portions 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 comprises the following steps: periodically broadcasting a beacon signal from said communications controller during a broadcast interval via a channel of a first host; the beacon signal includes a first address of the communication controller. The method also comprises the following steps: the first node periodically scans for a beacon signal of the first host, transmits an identification payload to the communications controller upon detection of the beacon signal by the first node, and transmits a reply signal to the first node upon receipt of the identification payload by the communications controller.

According to a preferred embodiment, the reply signal further comprises an instruction instructing the first node to perform at least one subsequent operation. One of the subsequent operations is that the first node enters sleep mode for a specified period of time. The other of which subsequently operates is that the first node is powered down.

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

According to a preferred embodiment, said first node enters a sleep mode for a second sleep time if said acknowledgement signal is not received within a predetermined time after sending said identification payload. In particular, the first sleep duration is longer than the second sleep duration.

According to a preferred embodiment, the communications controller broadcasts the beacon signal periodically over a plurality of time slots during the same broadcast interval via other channels on the first host having different broadcast frequencies.

According to a preferred embodiment, the communication controller periodically broadcasts at least one further beacon signal containing at least one further address of the communication controller on a channel of the second host during the same broadcast interval. The broadcast frequency of the same channel in different hosts is the same. According to yet another preferred embodiment, the communication controller comprises at least two hosts, each host periodically broadcasting three beacon signals; each host contains a different address for the communication controller and the broadcast frequency of the same channel on different hosts is the same.

According to a preferred embodiment, the communication controller comprises 8 hosts, and for one broadcast channel, the beacon signals of the 8 hosts are broadcast by the communication controller using different time slots, the total broadcast time being equal to or less than 30% of the broadcast interval time.

According to a preferred embodiment, a beacon signal of said first host is followed by a (following) beacon signal of said second host having the same broadcast frequency during a broadcast period within a broadcast period time.

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 predetermined time interval.

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

According to a preferred embodiment, the first node sends the identification payload to the communications controller upon detecting the beacon signal and only detecting that a beacon signal is present on the same channel during the next broadcast interval.

According to a preferred embodiment, when the signal strength of a beacon signal received by a first node is low, the first node will immediately connect to the address of the communication controller from which it received the beacon signal. Otherwise, the first node will be connected to an alternative address of said 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, a two-way communication system for logistics tracking is provided. 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 at a fixed broadcast interval time via a channel of the first host. The beacon signal includes a first address of the communication controller. The first node periodically scans for the beacon signal of the at least one host. The first node, upon detecting the beacon signal, transmits an identification payload of the first node to the communications controller. The communication controller sends a reply 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; periodically broadcasting, by the communications controller via a channel of the first host, a beacon signal at a fixed broadcast interval time, the beacon signal including a first address of the communications controller; wherein the first node periodically scans for beacon signals 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; the communication controller sends a reply signal to the first node upon receipt of the identification payload.

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

In particular, the two-way communication system for logistics tracking further comprises a remote server for collecting and recording 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 communications controller and a plurality of inventory-related nodes, including a first node; periodically broadcasting, by the communications controller via a channel of the first host, a beacon signal at a fixed broadcast interval time, the beacon signal including a first address of the communications controller; wherein the first node periodically scans for beacon signals on the first node; wherein the first node transmits an identification payload of the first node to the communications controller upon detecting a beacon signal; wherein said communications controller sends a reply signal to said first node upon receipt of said identification payload.

According to a fifth aspect of the present invention, there is provided a communications controller in a data network, the data network further comprising a plurality of nodes including a first node, the communications controller comprising: a processor, a memory for providing code to said processor, and an interface controlled by said processor: the communications controller periodically broadcasts a beacon signal at a fixed broadcast interval time via a channel of the first host, the beacon signal including a first address of the communications controller, and sends a reply signal to the first node upon receiving the identification payload from 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 communications controller and a plurality of nodes, including the first node. The first node comprises: a processor, a memory for providing code to said processor, and an interface controlled by said processor: the first node periodically scans a beacon signal broadcast by a first host of the communication controller and sends an identification payload to the communication controller after detecting the beacon signal, the first node enters a sleep mode after receiving a response signal and lasts for a first sleep time, and enters the sleep mode and lasts for a second sleep time if the first node fails to receive the response signal within a preset time after sending the identification payload.

[ description of the drawings ]

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

FIG. 1 is a system diagram of one embodiment of the present invention.

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

FIG. 3 is a block diagram of a tag of one embodiment of the present invention.

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

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

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

Fig. 6 is a signal diagram of a tag scanning window for detecting broadcast advertising beacons during a scanning phase in accordance with one embodiment of the invention.

Fig. 7 is a timeline of a tag wakeup period during a scan phase according to one embodiment of the invention.

FIG. 8 is a flowchart of the steps performed by the tag during the join phase in accordance with one embodiment of the present invention.

Fig. 9 is a schematic diagram of a logistics system application of one embodiment of the present invention.

[ detailed description of the invention ]

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

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

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

Standard bluetooth low energy applications for reading broadcast information are broadcasting information to smart phones, tablets and other devices using the iBeacon scheme. However, the bluetooth low energy standard has only 3 broadcast channels. In active RFID applications, the iBeacon scheme cannot be adopted since it can only provide 400 broadcast slots at most (according to 100ms iBeacon broadcast interval and 0.75 ms iBeacon packet transmission time). Although there are theoretically a maximum of 400 broadcast slots, the success rate of acquiring an intact broadcast beacon is greatly reduced because channel collisions can occur when there are a very large number of tags (e.g., thousands) in the coverage area. In addition, the iBeacon method is unreliable because it lacks an acknowledgement signal after data is received. Also, since the iBeacon scheme is a method that employs continuous broadcasting, the battery life of the tags cannot be optimized, and when a large number of tags are gathered together, the collision problem still exists. Furthermore, under FAA regulations, it is required to prohibit RF signal transmission from devices on an airplane in flight, and therefore RFID using this broadcasting scheme will not be allowed to be applied to an airplane.

FIG. 1 depicts a logistics tracking system 100 of 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, etc. The

tags

120, 121, and 122 are self-powered and periodically wake up from a sleep mode to detect the presence of the tag reader 110, thereby establishing wireless communication and sending identification data to the tag reader 110. The tag reader 110 records the identification data received from the

tags

120, 121 and 122 and transmits the data to other readers or a central monitoring station via a network (not shown). This data may be used to monitor the location of the objects associated with

tags

120, 121, and 122, and may also be used to generate messages that display object location information. Data transmission between the

tags

120, 121, 122 and the tag reader 110 is performed in a reliable and secure manner. According to one embodiment of the present invention, BLE topology is used to support reading a large number of tags within a spatial coverage area centered on the tag reader 110 with a radius of up to 50 meters.

Fig. 2 depicts a hardware block diagram of a tag reader 200 according to one embodiment of the invention. Tag reader 200 includes a processor 210 having an operating system and control software, processor 210 communicating with BLE beacon communicator 220 to establish wireless communication with a tag (not shown), tag reader 200 further including a cellular data adapter 230 and a WLAN module 240

Fig. 3 depicts a hardware block diagram of a tag 300 according to one embodiment of the invention. Tag 300 includes a controller 310 in communication with BLE communicator 320. Through BLE communicator 320, tag 300 is able to establish wireless communication with a tag reader (not shown) and thereby be able to scan for beacon signals and transmit identification signals, while receiving reply signals and commands and the like. The controller 310 controls the operation of the tag 300 in different modes, such as a scan mode, a connection mode, and a 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 a tag reader 410 and a tag 420 according to one embodiment of the invention. The tag reader 410 broadcasts the beacon signal 401 on an advertising channel of one BLE host with the identity of the broadcaster. As defined by the BLE standard, one BLE host contains 3 broadcast channels, namely channels 37, 38 and 39. If the broadcast interval time is set to 20 milliseconds, a maximum of 3 beacon signals can be transmitted every 20 milliseconds, which means that a total of 150 beacons per second are broadcast by each BLE host. The broadcast protocol and the broadcast status 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 is periodically woken up and detects the presence of a beacon signal 401 from the beacon reader 410 during a scanning interval. The scan interval (wake-up duration) 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 receiving the identification payload, the tag reader 410 transmits a response packet 403(acknowledgement packet) to the tag 420 to confirm receipt. The channel configuration in the broadcast procedure and the connection setup procedure will be further described as follows.

According to one embodiment of the invention BLE channels 37, 38 and 39 are allocated for broadcast and connection setup purposes. In particular, BLE may be used in Limited discovery Mode (BLE Limited discovery Mode) by setting a "Limited flag" on the connectible message packet, thereby enabling channels 37, 38 and 39 to operate in the broadcast phase and the connection setup phase. 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.

In the broadcast phase, the channels 37, 38, 39 are set as broadcast channels, allowing only downlink communication. The tag reader 410 sends a connectible message packet over the channels 37, 38, 39. In the connection setup phase, the channels 37, 38, 39 are set to support two-way communication.

On the tag side, a limited discovery process is used to find any nearby tag readers 410 that are operating in a limited discovery mode. When the tag reader 410 is found, the tag 420 attempts to connect with it. According to the BLE standard, the connection setup procedure is performed over these 3 broadcast channels 37, 38, 39. After completing the connection, the tag reader 410 and tag 420 will exchange data (e.g., identification payload) over one available channel of the 37 data channels (0-36) defined by the BLE standard. The connection setup procedure is discussed in detail in the bluetooth technical manual specification v4.0, volume 6, section 4.4.4 (start-up state and connection state).

After the connection setup, all data transmissions (e.g., identification payloads) on the data channels (0-36) will be established according to the GATT configuration on the L2CAP connection. The connection may be encrypted to enhance 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 invention, the reply packet 403 also includes a control byte that allows the tag reader to instruct the tag 420 to perform a subsequent action. For example, to optimize tag power consumption, the control byte may indicate a preset sleep duration before the tag 420 wakes up to detect the broadcast beacon again. In another example, the control byte may indicate that the tag is powered off.

According to one embodiment of the invention, the tag reader may be powered by an AC power source, in which case power consumption considerations are less important. Fig. 5a is a signal diagram of the broadcast beacon duration and interval times for a tag reader having

multiple hosts

510, 520, etc. in accordance with one embodiment of the present invention. The BLE beacon communicator on the tag reader comprises a group of 8 independent BLE host modules, and 3 LSB bits in bluetooth addresses of the BLE host modules are different and are fixed to be 0-7 (as shown in fig. 1 and 2). The channel of each BLE host module (e.g., 510) independently broadcasts a unique beacon ID (e.g., 511) within a minimum interval time 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 has the same frequency as the channel 37 of the second host 520. Beacons of different hosts on the same advertising channel preferably do not overlap in the time domain to avoid interference with each other. From the 3 beacons (511, 512, 513) per BLE host every 20 milliseconds, each BLE host may broadcast 150 beacons per second. With 8 BLE hosts, the tag reader has a total of 1200 beacon broadcasts per second. Therefore, the chance of a tag successfully connecting to one available channel of the 8 BLE host channels 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 scanned depends on the detection time required when the maximum number of tags are present within the tag reader coverage.

According to one embodiment of the invention, the beacon packet duration is about 750 microseconds, and the broadcast interval time is set to 20 milliseconds, so that at most 20/0.75 × 3 ═ 80 broadcast channels can be provided, i.e. theoretically 80 BLE broadcast slots can be used. However, since there is a possibility that collisions may occur between beacons using the same time slot, it is preferable 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, an 8x 3/80-30% broadcast time slot is utilized. As the number of tag readers in the coverage area increases, the optimal balance between high tag reading rate and low beacon collision rate can be achieved by increasing the broadcast interval time to more than 20 milliseconds so that the utilization of the broadcast slots remains at 30% or less for each broadcast channel, thereby keeping the beacon collision probability at a reasonably low level.

According to another embodiment of the present invention, when one tag reader has 16 BLE hosts, the broadcast slot utilization per broadcast channel can be as high as 60% without creating significant beacon collision problems. Setting the broadcast interval time of each host to 20 milliseconds as an optimal configuration enables the beacon collision probability to be at a reasonably low level, thereby achieving the best balance between high tag read rates and low beacon collision rates.

For most typical use cases, it is sufficient to achieve a reasonable read rate when a tag reader has 8 hosts and the broadcast interval time for each host is set to 20 milliseconds to achieve 30% broadcast slot utilization (for each broadcast channel). On the other hand, for scenarios where a relatively large number of tags need to be detected at the fastest read rate, a 60% broadcast slot utilization of 16 hosts (for each broadcast channel) is the best implementation.

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

Fig. 5b is a signal diagram of a broadcast beacon duration and time interval for a tag reader having

multiple hosts

510, 520, etc. according to another embodiment of the present invention. The beacon order of the same channel on different host modules is correlated in the time domain such that one host module 510 is separated by a preset time between the first beacon 515 on channel 37 (first broadcast frequency) and the first beacon 516 on channel 37 (same first broadcast frequency) of another host module 520. In other words, beacons on the same broadcast channel of different hosts are separated by a preset time.

Fig. 6 shows a signal diagram of a tag scanning window for detecting broadcast beacons during a scanning phase according to an embodiment of the invention. The beacon detection rate depends on the scan interval period time 610 and the scan window duration 620 of the tag. 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 that a beacon will not be detected because the tag may scan within a time window in which no beacon is present. On the other hand, a longer scan window time has a large impact on the power consumption of the tag, since the power consumption is closely related to the length of time the radio circuit has to be switched on. The scan interval period time 610 and scan window duration 620 parameters determine how often and for how long a scanner device (e.g., tag) will listen for potential broadcast beacon packets. As with the broadcast interval, these values have a profound effect on power consumption, as they are directly related to the length of time that the radio circuit must be turned on.

One consideration in system design is to conserve tag power consumption (low duty cycle RF activity) because it is desirable to use a small size battery, such as a button cell, for ease of mounting on the cargo. Power consumption is not an issue for the reader since the reader is typically operated in a fixed location and therefore can be connected to an external power source. For this reason, the reader may assume a more powerful CPU and higher duty cycle RF activity. The tag's scan interval cycle time 610 and scan window duration 620 may be set to optimize its battery life while increasing the rate of tag detection by adjusting the tag reader's aggressive broadcast time interval (every 20 milliseconds at the fastest).

According to one embodiment of the invention, a beacon broadcast duration is approximately 750 microseconds. The broadcast beacons of channels 37, 38 and 39 are transmitted continuously. The total broadcast time of these 3 beacons is approximately 750 microseconds × 3 ═ 2.25 milliseconds. To optimize the battery life of the tag, the scan window duration of the tag may be set to 3 milliseconds and scanned at a cycle of waking up once every 2 seconds (i.e., a scan interval cycle time of every 2 seconds). Since 3 milliseconds can cover the duration of 3 broadcast advertising beacons, there is enough opportunity for a tag to detect one of the broadcast beacons of one of the tag readers (with 8 BLE hosts).

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

FIG. 7 is a timing diagram of a tag wakeup period during a scan phase according to one embodiment of the invention. The tag needs to be able to detect the beacon ID of the tag reader in order to initiate a connection with that particular 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 goes back to sleep until the end of the scan cycle interval. During the scanning phase, only the receiving 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 that tag battery life is extended and that RFID tag applications can be turned on in the aircraft. In the cabin, without the tag reader, the tag 300 will not detect the beacon ID, and therefore the tag will enter a sleep phase and will not turn on the transmitter circuitry to send the identification payload throughout the flight. In another embodiment, the tag will not enter a sleep phase, but rather is set to enter a scan phase in which the transmitter circuitry 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 may be implemented.

According to one embodiment of the present invention, it may be possible to ensure that there is sufficient BLE master to be accessed by the tag by increasing the number of tag readers (i.e. increasing the ratio between the reader and the number of tags that need to be read) and uploading a single tag payload to the tag reader. The faster the tag sends its payload, the faster it goes to sleep, thereby extending battery life. More BLE hosts (more tag readers) and fewer connection retries will increase the battery life of the tag.

According to one embodiment of the invention, a tag reader has 8 masters whose broadcast beacon interval period is optimally set to 20 milliseconds times the number of tag readers to maintain 30% broadcast slot utilization (for each broadcast channel).

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

Setting a longer broadcast interval period for broadcast packets can reduce the probability of beacon collisions, but will also reduce the rate at which tags are discovered and connected. This requires a balance between the number of host channels and the period of the broadcast interval for the tag detection rate. According to one embodiment of the invention, 20 milliseconds is chosen as the shortest broadcast interval period to achieve 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 wake-up interval period during which the tag periodically scans for the tag reader beacon ID. When a coin cell battery is used, the optimal value for the wake-up interval period 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 discovers the tag reader, it proceeds to step 704 to send an identification payload and enters sleep mode. While the wake-up interval time is set to several minutes so that other tags have more opportunities to connect with the tag reader. Once the set sleep time is over, the tag will wake up and execute step 705, again scanning for broadcast beacons.

FIG. 8 is a flow chart of the steps performed by a tag during the connection phase in accordance with one embodiment of the present invention. To establish a connection, the tag first scans for BLE hosts on the tag reader that have detected a beacon, beginning at step 801. This extra scanning step is to ensure that the host is still available and not occupied by other device connections before the connection.

According to an embodiment of the present invention, the scanning window and the scanning interval period are both set to 30 ms, and the total time is 90 ms, so as to allow the tag to complete scanning all 3 broadcast channels of a specific BLE host (step 803-808). If the beacon has not been detected at the end of the 90 millisecond time, step 810 is entered and the tag will repeat the scanning process in a random manner for the remaining 7 of the 8 BLE hosts of the tag reader. If a beacon is successfully detected, the tag will proceed to step 809 to send a connection request to the BLE host, and then finish sending the payload to the tag reader (step 812). If the beacon is not successfully detected after all 8 hosts of the tag reader have been tried (step 811), the tag will go to step 813 to sleep and wake up after 2 seconds to detect the broadcast beacon again.

Setting the scanning window and the scanning interval period to the same value, according to one embodiment of the present invention, will enable BLE tags to continuously scan on 3 advertising channels of the same host. Initially, the broadcaster (reader) and the scanner (tag) may not be on the same channel. This is also why 3 broadcast channel time intervals need to be considered when setting the total scan time. According to the BLE technical manual specification, a random time shift (time shift) is added to the broadcast packet start time during each broadcast period, thereby avoiding persistent collisions of broadcast packets between different hosts. According to one embodiment of the present invention, 20 ms times 3 is not set as the total scan time, but 30 ms times 3 is used to match the time shift requirement. The scan protocol and scan state time are described in detail in the bluetooth technical manual specification v4.0, volume 6, section 4.4.3.

According to another embodiment of the present invention, the tag may be set to sleep for an adjustable sleep time or enter a power-off state by a control byte in the reply packet of the tag reader. When the tag has successfully sent its identification payload to the tag reader, the tag reader will send a reply packet containing a control byte to the tag to confirm the receipt. The control byte is internally provided with a wake-up time for setting the label or a parameter for indicating the shutdown of the label. After the tag successfully sends the identification payload, the tag is set to enter a longer wake-up interval time, so that the situation that the tag and other tags compete to access a BLE host of the tag reader can be effectively avoided. The value of the tag wake-up interval may 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 tag, the tag reader may also use the tag ID to determine transit time as tagged goods leave the warehousing area and are transported by land, sea, or air. The tag reader may query the central server using a cellular data network or WiFi to determine its current location, while the time that the tagged item is sensed by the tag reader of the next warehousing area to which the tagged item is to be delivered, to determine the shortest transit time for the tagged item. When the tagged item has reached its final destination, the tag reader will instruct the tag to shut down so that power is not consumed during its return to the original tag distribution. In the logistics supply chain, it is estimated that tags require only 15% of the time for an active scanning tag reader. By using the tag reader to control the sleep time and shutdown sequence of the tag, the battery life of a button cell operated tag can be extended to 4-6 years before the battery needs to be replaced or the tag replaced. Therefore, the running cost of the active RFID BLE label system using the invention is very economical and practical.

Fig. 9 is a schematic diagram of an application of a logistics system 900 in accordance with one embodiment of the present invention. Depending on the application of the active RFID system, in one embodiment of the invention, the tag 902 may be set to wake up or be turned off for the same/longer time interval. In another embodiment of the invention, the tag 902 may be configured to wake continuously when an active RFID tracking system is used to detect the dwell time/transfer of the tracked cargo. 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 itinerary and schedule of the tagged items, such as when the items are detected in an airport warehouse and moved to a shipping warehouse for shipment to another location. At the shipping station, the tag reader 903 may set the tag 904 to sleep continuously for the time it is in flight or transported to the destination, thereby extending the battery life of the tag.

When the tagged item has reached its destination, the tag reader at the arrival area can set the tag to power off so that the tag can extend battery life, be turned back on after being returned to the item distribution center, and be assigned to another item for system tracking.

According to another embodiment of the invention, the tag will calculate the Received Signal Strength Indication (RSSI) from the strength of the received broadcast packet beacon signal transmitted by the host of the tag reader.

In the case where there are thousands of tags within the coverage of the tag reader, the tags will compete to be able to securely connect to the 8 BLE hosts of the tag reader. When the tag scans a beacon of the tag reader, a bluetooth address of the specific BLE broadcast channel is obtained, and the rest BLE broadcast channels on the tag reader can be deduced through mapping of the corresponding bluetooth address. Along with the RSSI data information of the detected beacon, the tag can determine whether the tag reader is far away or close.

More specifically, the RSSI value and bluetooth LSB fixed address of the tag reader may be used to enable the tag to perform random tag reader channel connection, thereby enabling efficient use of the BLE channel of the tag reader 8 BLE hosts. When there are a large number of tags within the tag reader coverage, the chances of multiple tags detecting the beacon of the same particular BLE host are large, especially when some BLE hosts have RF transmitters that transmit stronger signals than other channels. If multiple tags attempt to connect to the same BLE host, it is likely that most tags will fail and the attempt will be repeated. This will result in the channel being occupied (channel sounding) and multiple retries will shorten 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 (LSB of BLE host, fixed to 0-7), deduce from the bluetooth address of the currently broadcast beacon 8 BLE hosts are available and attempt to connect. The tag may also determine whether the tag reader is far away from or close to the tag based on the RSSI value of the detected beacon.

Using the RSSI and bluetooth address information of the detected beacon, the tag can choose two methods of securely connecting to the tag reader. If the RSSI value is good, it means that the tag is close to the reader. At this time, the tag can use a random channel connection method, and randomly use any one of 8 bluetooth addresses of the tag reader for connection, thereby reducing channel occupation (the tag attempts 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 is selected for retry according to a random hash algorithm. This process will continue until all 8 BLE hosts have been attempted, or the identification payload of the tag is successfully sent to the tag reader. Thus, it is possible to prevent tags from competing with each other to acquire the same channel connection, thereby improving the success rate of connecting tag readers.

On the other hand, if the RSSI value of the detected beacon is not good, indicating that the tag may not connect to other hosts, the tag will only use the currently detected BLE host to set up the connection, and will not retry the other 7 BLE hosts to connect. This avoids shortening battery life by attempting to connect to other BLE hosts that may not be able to connect.

While the invention has been described in conjunction with various embodiments, it is to be understood that the invention is not limited to those embodiments, but is also amenable to various substitutions, modifications and changes by those skilled in the art without departing from the scope of the invention. For example, the tag reader may be implemented by software, which is executed by a handset or processor.

Claims

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;

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.