There is a strong market need for an indoor electronic positioning system that can provide one-meter accuracy or better. Mobile retail applications for smartphones are one of the biggest revenue drivers behind this need, allowing users to, among other things, determine what is currently on sale in the aisle of the store they are in, determine which items from their shopping list are sold in the aisle they are walking in, or simply to obtain information about a nearby product or display.
One indoor positioning technique that has become popular recently leverages the Bluetooth® Low Energy (BLE) wireless standard for indoor proximity detection. Apple, Inc. has published a standard for so-called “iBeacons”—low-powered, low-cost BLE transmitters that can notify nearby iOS® 7 devices of their presence. This technology enables a smart phone or other device to perform actions when in close proximity to an iBeacon. One application is to help smartphones determine their precise position. With the help of an iBeacon, a smartphone's software can pinpoint its own location in a store. The vision was for retail store management to place numerous small, coin-cell battery-powered iBeacon emitters in various positions throughout the store (e.g. every 6-10 feet along each aisle). Each iBeacon would periodically (typically once per second) broadcast a BLE advertisement message containing its universally unique identifier (UUID), and smartphones moving around the store could locate themselves by listening for the iBeacon transmissions and determining their position by looking up the UUID of the closest (i.e., producing the largest received signal strength) iBeacon in a database. A similar BLE-based proximity sensing technique has been introduced for Android® smartphone devices.
There are a number of challenges with Apple's original vision: (1) retail store owners do not like to replace batteries, (2) installing discrete iBeacons in a retail store leaves them prone to theft or damage, (3) there is no centralized way to configure or control the iBeacons, to update their firmware, to change their operating parameters (e.g., Tx beacon interval, Tx power, etc.) or to run health checks to ensure they're working properly, (4) the iBeacons all transmit at the same frequencies but are not time-synchronized, so some of their transmissions will interfere with one another.
Another challenge concerns battery life on the smartphone. Since the iBeacons run off of a small battery, they can send out BLE advertisements no more frequently than once per second without emptying their batteries too quickly. This means that the smartphone needs to keep its receiver powered on with a very high duty cycle (at least 50%) to hear a sufficient number of the iBeacon transmissions to ensure a reasonable location update rate (e.g., once per two seconds on average). This high of a receiver duty cycle will have a significant negative impact on the smartphone's battery life.
The skilled artisan will understand that the drawings, described below, are for illustration purposes only. The drawings are not intended to limit the scope of the present teachings in any way.
Before one or more embodiments of the present teachings are described in detail, one skilled in the art will appreciate that the present teachings are not limited in their application to the details of construction, the arrangements of components, and the arrangement of steps set forth in the following detailed description or illustrated in the drawings. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.
Various embodiments are presented herein for a cable assembly. The cable assembly integrates a DC power supply and a plurality of BLE radios such that one or more cable such assemblies can be arranged/positioned along the aisles of a retail store or in other similar environments. The BLE radios are powered from either an IEEE 802.3af/at-powered local area network (LAN) switch or from an AC outlet, so that there is no need to replace batteries of the cable assembly. This integrated cable approach makes it easy to hide the cable in or alongside the shelving units or other structures in deployment environment to avoid theft or damage. Each cable assembly has an integrated central processing unit (CPU) and a serial data bus to configure and control the BLE radios, and can communicate with other networking equipment such as a centralized web sever on a network via IEEE 802.3 wired Ethernet or a Wi-Fi® wireless local area network (WLAN). The serial data bus and network connectivity also allows the cable assemblies to time-synchronize their BLE transmissions in order to minimize interference. The centralized control capability also allows for centralized configuration and control, health checking and firmware updates for all deployed BLE radios. Finally, since battery life is not a concern for the cable assembly presented herein, the BLE radios can be configured to transmit BLE advertisements much more frequently than their battery powered counterparts, allowing the smartphones and user devices to scan less frequently and thus conserve battery life.
The CU 110 may take the form of a long (up to 300 feet), flat cable containing one or more conductors 155 for DC power, one or more conductors 150 for ground and low-speed serial data that is passed between the microprocessor 170 and the BLE modules 130-133. Each BLE module is typically small but flat—typically 9×12×1 mm. Thus, the CU 110 may be flat instead of round—and may contains one or more system-of-chips (SoCs) to implement that BLE MAC, PHY and RF portions, a voltage regulator, an RF front-end, and a 2.4 GHz antenna. The one or more conductors 150 for serial data bus are used to carry messages and data between the microprocessor 170 and the BLE modules.
The antenna (not shown) associated with each BLE module can either be omnidirectional or directional. Using directional antennas that are aimed toward the center of each aisle could help the mobile user device determine on which aisle (i.e., which side of the cable assembly) the mobile user device is located.
One potential challenge with the design of the CU 110 is the voltage drop in Vcc in the conductor(s) 155 along the length of the cable. An effective way to mitigate this issue is to source a high DC voltage at the output of the DC/DC converter 165 so that it is just high enough to power the last BLE module 130 at the end of the longest planned CU. A fixed resistor can be used between the Vcc line 155 and the Vcc input to the BLE modules that are closer to the DC/DC converter 165 in order to limit the input voltage to the BLE modules. The closer the BLE module is to the DC/DC converter 165, the larger the required voltage drop and hence the larger the resistor value for the resistor to be used.
The PCM 120 and CU 110 can be integrated together into one physical structure as shown in
One useful alternative to the PCM 340 shown in
The mobile devices 640 and 641 are typically battery-powered mobile wireless user devices such as smartphones or table computer device that contain a BLE chipset as well as 802.11/Wi-Fi and cellular chipsets.
Referring again to
The BLE modules 130-133 can be configured as either BLE emitters or sensors. In emitter mode, the BLE modules transmit BLE advertisements periodically at some interval specified by the CPU 170 of PCM 120. The mobile reports the UUID and received signal strength (RSS) of the closest (i.e., having max RSS) emitter to the server, and the server reports back the location coordinates of that emitter. An improved location estimate can be obtained if instead of reporting the RSS of the closest emitter, the mobile device reports the UUID and RSS for all “detectable” BLE emitters (i.e., above the mobile device's receive noise floor). This will allow the server to triangulate on the mobile device's position using the relative positions and received signal strengths from the multiple BLE emitters. The mapping of the UUID and RSSs to the location can also be performed on the mobile device instead of the server provided that it is equipped with a table containing the physical location and UUID of each emitter.
In a sensor mode, the BLE modules are configured to continually scan their receivers, looking for BLE advertisements sent from the mobile device. When a sensor hears an advertisement, it passes the mobile UUID and RSS of the received advertisement to the location server through the CPU and MAC/PHY 170 of the PCM 120. The server can then estimate the location of the mobile (using either triangulation or a nearest-sensor approach) and periodically pass the location information back to the mobile device by sending it a message over the local Wi-Fi or cellular internet network.
After receiving the health check response from the CPU, the server sends back a message directing it to put the BLE modules into emitter mode, transmitting beacons once per 100 ms, for example. The CPU directs each of the modules to begin an emitter mode session using a 100 ms beacon interval, and the modules begin transmitting the beacons. The mobile device detects one or more of the beacons, and sends a Location Request message to the server containing the UUID and RSS for each of its received beacons. The server then responds with Location Response message containing the estimated position of the mobile device.
As described above, each cable assembly has tight control over transmission made by each of its BLE modules. Since each cable assembly can communicate on the store's network via a LAN or Wi-Fi connection, it is possible to time synchronize all of the cable assemblies (as well as all of the BLE modules on all of the cable assemblies) in the store to a common timebase in order to minimize interference. For example, the cable assemblies could use the Network Time Protocol (NTP) to synchronize their clocks to one global time base, and use time-division multiple access (TDMA) to arbitrate their transmissions so as to minimize the likelihood that any two cable assemblies that are in close physical proximity to one another transmit their BLE advertisements (or any other BLE information) at the same time and on the same frequency.
An alternative to the cable assembly design of
In summary, in accordance with one embodiment, a cable assembly is provide that includes a cable; one or more radio transceivers spaced along the length of the cable; and a first set of one or more conductors within the cable to supply DC power and ground to the one or more radio transceivers. The cable assembly may further include a second set of one or more conductors within the cable to carry communication and control signals to the one or more radio transceivers.
In one form, the cable assembly may include a first connector at one end of the cable, the first connector configured to connect to an external device from which the DC power, ground, the communication signals and control signals are supplied to the one or more radio transceivers via the first and second sets of one or more conductors. Moreover, a second connector may be provided at the other end of the cable, the second connector configured to provide DC power, ground, communications and control signals to the radio transceivers on another cable assembly.
The external device (e.g., power conditioning module) includes: a control processor that supplies the control signals to the one or more radio transceivers via the second set of one or more conductors, a network interface port, a network media access control/physical layer MAC/PHY processor that carries local area network (LAN) data between the control processor and a LAN via the network interface port, and a power converter circuit that obtains DC power and ground signals from the network interface port for supply to the one or more radio transceivers via the first set of one or more conductors. The control processor, network interface port, network MAC/PHY processor and power converter circuit are contained within a housing that is connected to the cable.
In one form, the cable assembly further includes: a control processor that supplies the control signals to the one or more radio transceivers via the second set of one or more conductors, a network interface port, a network media access control/physical layer MAC/PHY processor that carries local area network (LAN) data between the control processor and a LAN via the network interface port, and a power converter circuit that obtains DC power and ground signals from the network interface port for supply to the one or more radio transceivers via the first set of one or more conductors.
In another form, the cable assembly further includes: a control processor that supplies the control signals to the one or more radio transceivers via the second set of one or more integrated conductors, an AC power cable and plug, a wireless local area network (WLAN) transceiver, a WLAN MAC/PHY processor that carries local area network (LAN) data between the control processor and a LAN via the WLAN transceiver, and an AC-to-DC converter that converts AC power from the AC power cable to DC power and supplies the DC power and ground to the one or more radio transceivers via the first set of one or more integrated conductors.
In accordance with another embodiment, a cable assembly is provided that comprises: a cable; a radio transceiver; a control processor; a plurality of switched antennas spaced along the length of the cable; one or more integrated conductors within the cable that connect the control processor to a control port on each of the plurality of switched antennas, and one or more integrated transmission lines within the cable that connect the radio transceiver to each of the switched antennas. The control processor configures the plurality of switched antennas so that the radio transceiver is connected to only one of the plurality of switched RF antennas at a time. The radio transceiver may be a Bluetooth Low Energy transceiver that transmits using a different universally unique identifier (UUID) depending to which of the plurality of switched antennas the radio transceiver is connected, and the control processor and radio transceiver may be contained within a housing that is connected to the cable.
In accordance with another embodiment, a system is provided comprising: a plurality of cable assemblies, each cable assembly comprising: a cable; one or more radio transceivers spaced along the length of the cable; and a first set of one or more conductors within the cable to supply DC power and ground to the one or more radio transceivers; at least one network switch connected to the plurality of cable assemblies, wherein the network switch enables network connectivity to the one or more radio transceivers of each cable assembly; and a server configured to be in network communication with the plurality of cable assemblies and to track locations of one or more mobile wireless user devices with respect to respective radio transceivers in each of the plurality of cable assemblies.
Each of the radio transceivers in the system emits a wireless signal that includes an identifier, and wherein a mobile wireless user device detects the wireless signal from one or more radio transceivers, obtains the identifier contained in the detected wireless signal, and sends to the server a report the identifier and received signal strength of the wireless signal detected from one or more radio transceivers. Each of the radio transceivers in each cable assembly is a Bluetooth Low Energy transceiver. The server computes a location of the mobile wireless user device based on the report. The server may send to each of the radio transceivers a message directing each radio transceiver to operate in an emitter mode such that each radio transceiver emits a beacon on a periodic basis.
The above description is intended by way of example only. Various modifications and structural changes may be made therein without departing from the scope of the concepts described herein and within the scope and range of equivalents of the claims.
This application claims the benefit of U.S. Provisional Patent Application No. 61/876,301 filed Sep. 11, 2013, the entirety of which is incorporated herein by reference.
Number | Date | Country | |
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61876301 | Sep 2013 | US |