Patent Application
20150271642
1. Field of the Invention
The invention relates generally to wireless networks.
2. State of the Prior Art
In wireless networks the problem of allocating transmission rights to subsets of network users or devices at each time and under different channel qualities is generally known as a scheduling problem. It arises in wireless environments because of three main reasons related to the fundamental properties of the wireless medium. Specifically, scheduling is mandatory since in wireless environments (i) communication resources are shared among geographically separated users, (ii) transmissions may interfere with each other, and (iii) transmissions undergo impairments, such as fading, attenuation, etc.
The scheduling issues at any given time are about identifying the user that are allowed to transmit and their corresponding transmission power levels and rates. Often, a delay mechanism may be used to control traffic in a wireless network. For instance, each sensor may be on a fixed interval timer for transmissions. An interval for one timer may be different than an interval for another timer. In this manner, a transmitter can have a certain probability of having its transmission go through occasionally or semi-regularly, if not always. This type of scheduling accordingly may lead to communication collisions. The number of collisions is statistically related to the number of sensors in a particular network. Naturally, even a system with just two sensors, where those two sensors have different timing, will result in collisions.
Additional objects, advantages, and novel features of the invention are set forth in part in the description that follows and others will become apparent to those skilled in the art upon examination of the following description and figures or may be learned by practicing the invention.
To achieve the foregoing and other objects in accordance with the purposes of the present invention, as embodied and broadly described herein, an embodiment of the invention may therefore comprise a method of locating a sensor in a network comprising a plurality of sensors and a base unit, the method comprising via a location device, emitting a signal detectable by at least one of the plurality of sensors, activating a microphone in the at least one of the plurality of sensors, via a user, moving the device from a first location to a second location, via the at least one of the plurality of sensors, detecting the signal emitted by the location device, the via the at least one of the plurality of sensors, transmitting a responsive signal to indicate proximity of the locating device to the at least one of the plurality of sensors.
An embodiment of the invention may further comprise a method of locating a sensor in a network comprising a plurality of sensors and a base unit, the method comprising via at least one of the plurality of sensors, emitting a location signal, via the location device, detecting the location signal, displaying a location metric related to the detected location signal on the location device, via a user, moving the location device from a first location to a second location, if the second location is closer to the at least one of the plurality of sensors than the first location, via the location device, communicating with the at least one of the plurality of sensors to modify the location signal, and via the at least one of the plurality of sensors, modifying the location signal.
An embodiment of the invention may further comprise a system for locating a sensor in a network, the system comprising a base unit, a mobile location device enabled to transmit a signal, and a plurality of sensors comprising a microphone wherein each sensor is enabled to detect the signal transmitted by the location device and to transmit a responsive signal to indicate proximity of the mobile location device, wherein the responsive signal varies in strength depending on the proximity of the mobile location device to a sensor that is transmitting the responsive signal.
An embodiment of the invention may further comprise a system of locating a sensor in a network, the system comprising a plurality of sensors wherein each of the plurality of sensors is enabled to emit a location signal and modify the location signal pursuant to a command, and a mobile location device enabled to detect the location signal, display a location metric related to the detected location signal and command a sensor of the plurality of sensors to modify the location signal pursuant to the location metric.
An embodiment of the invention may further comprise a method of estimating battery life in a wireless device in a network comprising a plurality of sensors and a base, the method comprising via the base, the base comprising a computing device, calculating the total number of clock cycles that one of the plurality of sensors has been awake, and calculating the power consumption of the one of the plurality of sensors according to a predefined algorithm.
An embodiment of the invention may further comprise a method of optimizing power in a wireless network, the network comprising a plurality of wireless sensors and a base unit, the method comprising by the base unit, calculating a power metric for each of the sensors of the plurality of wireless sensors, for each sensor of the plurality of wireless sensors, establishing a signal route for transmissions that utilizes the least power according to the power metric, scheduling an awake time for each sensor in the plurality of sensors in a unique time slot during a predefined period of time.
An embodiment of the invention may further comprise method of optimizing placement of sensors in a wireless network, the network comprising a plurality of wireless sensors and a base unit, the method comprising, via a user, placing a first of the plurality of sensors in a placement mode, via the first of said plurality of sensors, emitting a human perceptible signal wherein the signal indicates one of a signal quality and an estimated battery life for the sensor, via the user, and mounting the sensor.
The accompanying drawings, which are incorporated in and form a part of the specification, illustrate the preferred embodiments of the present invention, and together with the written description and claims, serve to explain the principles of the invention. In the drawings:
An embodiment of the invention comprises a scheduled communication system. A plurality of sensors are enabled to communicate to a central hub or communications center. Each of the sensors may be given a defined time slot in which to communicate. A routing table may be used to define the time slots for each of the sensors. The use of defined time slots aids in the prevention of sensor interference with each other. For instance, instead of a sensor having a random periodic communications schedule, each sensor will be schedule so that no other sensor is communicating at the same time. As an example, if a first sensor communicates every third of a second and a second sensor communicates every half second, then there will be an interference every second. It is noted that this is an example of interference using a very simple periodic scheme. Those skilled in the art will understand that variable periods may be used or other more complicated schemes. However, the probability of interference does not vanish, or go to zero, with more complicated schemes. The embodiments of the invention, however, eliminate the probability of interference.
The use of scheduling of sensors in defined time slots also preserves power, by reducing power usage, of the scheduled sensors. This may be especially important in the case where a sensor needs to act as a repeater. As is understood by those skilled in the art, a repeater is a device that receives a signal and retransmits it at a higher level or higher power. This may include transmitting a signal to the other side of an obstruction, so that the signal can cover longer distances. Based on a defined schedule, a sensor will know when to wake up and receive power from another device. As such, a sensor can be asleep much longer. Each sensor will have an internal clock that is precisely synchronized with a base station to allow accurate time slices. Synchronization in conjunction with defined scheduling allows for a larger number of sensors to communicate in a given time period. Accordingly, it is possible that only one sensor at a time is awake and communicating. Wake up times will be staggered according to the schedule. This provides the mentioned energy savings as well as a reliability of information. As more sensors are added to a network, coverage improves and additional paths due to synchronization and scheduling increase reliability. There is no increase in signal conflict, or interference, due to the scheduling of sensor transmissions and associated awake times. Throughout this description, the base unit may be described as a base station, which terms are used interchangeably.
It is understood that in order for accurate scheduling of sensor activity, that the wireless network needs to synchronize the clocks of the sensors, which will reside in a chip or other device in the sensor. Transmission changes take time. A ‘start time’ beacon, or signal will be initiated by a base unit. After a period of time, for instance two or three minutes, a ‘stop beacon’, or signal, will be sent by the base unit. The time between the beacons is used to synchronize the clocks of the sensors. The time between the beacons is several orders of magnitude longer than the maximum latency of a transmission and therefore the transmission latency can be assumed to be zero, respectively. Each sensor must have an accurately synchronized time clock. The base station will send out a synchronization signal. After a significantly longer period of time than the latency of the transmission, the base unit will send out a second signal. The time between the two signals is known. This allows for an accurate synchronization.
As noted throughout this description, battery life of a sensor is an aspect that requires monitoring. A low battery needs to be serviced to ensure continued proper operation of a sensor. A wireless network may indicate battery life based on the battery voltage. However, with certain types of batteries, such as lithium, the voltage levels may be relatively constant until the battery is less than 10% charged, for example. In an embodiment of the invention, the total amount of energy drawn from a battery is monitored. This may be accomplished by tracking the total clock cycles that a sensor is awake and the known power use of a sensor. A method of quantifying energy is provided in this description. The calculation will include the time, power of transmissions, time of transmissions. It is understood that other factors which may indicate battery usage at a certain level may be used. The total battery power available in a battery may be used as an amount against which to compare the power used. When a new battery is placed in a sensor, the battery level can be reset in a base to a predefined level based on the type of battery used and known characteristics of a battery used. The system may also sense an initial level of a battery and use the sensed level of a battery against the determined power usage of a sensor.
In an embodiment of the invention, each of the plurality of sensors will be able to connect to a base station. The base station is enabled to update each of the wireless sensors. The update will be accomplished via a wireless network. It is understood that in a large facility, the ability to locate and interact with sensors is not often easy. Many times, sensors are located in hard to access locations and may require the movement of large equipment. The ability to update the wireless sensors eliminates this physical task of locating the sensors.
In addition to wireless updating of sensors, sensors may also need to be serviced physically nonetheless. In an embodiment of the invention, locating the sensors is a primary task to such service. It is understood that this service may include battery replacement, repair or other service that is understood in the art. In an embodiment of the invention, a portable device, such as a smart phone or similar specialized device, is utilized to hone in on the location of each particular sensor. An initial step is for the device, or smart phone, to command a sensor to be located. This command, and receipt by the sensor, will initiate a transmission by the sensor. The device, or smart phone, is enabled to detect the relative amplitude of the signal that it then receives from the sensor. The device, or smart phone, is further enabled to display the relative amplitude of the signal that it is receiving. This allows a user to move in an area and determine when it is closer to a sensor. The sensor locations are more easily determined in this manner. A smart phone is a mobile phone with more advanced computing capability and connectivity than a basic feature phone. A smart phone may operate on an operating system that allows utilization of features such as a touchscreen computer, including web browsing, Wi-Fi, and 3rd-party apps and accessories. It is understood that smart phones and accompanying applications may allow for a smart phone to receive and transmit a variety of different known signal types, read barcodes and process data.
In a related embodiment of the invention, a sensor may have an LED (Light Emitting Diode) indicator and audible alarm. The LED and audible alarm may be utilized in the sensor location process. For instance, upon receipt of a command from the device 220, or base station, the sensor 210 may be commanded to illuminate a small LED to provide a more prominent visual alert. Further, the sensor 210 may be commanded by the device 220, or base station, to produce an audible alarm. The audible alarm from the sensor 210 is used similarly to the LED indicator to provide ease in location. The audible alarm and LED indicator can be used together or separately. For instance, a device 220, or base station, can command that a sensor 210 activate its LED indicator. If the LED indicator is unsatisfactory in locating the sensor 210, the device 220, or base station, can command that a sensor 210 activate its audible alarm. As is understood, the LED indicator and the audible alarm may be activated simultaneously. Also, a user with a mobile device 220 may directly control the activation of the LED and audible alarm. The user, through the use of an App, can command the base station to produce whichever alert is desired. The use of alerts can be used independently, or in conjunction with the location signal discussed above. It is understood that the location signal, while similar to the audible alert, is operationally different. The location signal of a sensor 210 will produce a signal in a form that is sensible by the device 220. That signal may be a Radio Frequency (RF) signal or an ultrasonic signal. Those skilled in the art will understand that other types of signals are useable by a sensor and transceiver and the embodiments of the invention are not limited to an RF or ultrasonic signal. These may include, but are not limited to, Near Field Communications (NFC). Those skilled in the art will understand that NFC is a set of standards for smartphones and similar devices to establish radio communication with each other by touching them together or bringing them into proximity with each other. NFC can include a variety of protocols and data exchange formats and are based on existing radio-frequency identification (RFID) standards. NFC may be used to instantly pair a sensor and a device. The pairing may be disabled automatically on both the sensor and the device once the desired task has been completed. Further, as is understood by those skilled in the art, RF signaling techniques may use triangulation methodologies. Triangulation is a process by which the location of a radio transmitter can be determined by measuring either the radial distance, or the direction, of the received signal from two or three different points. Triangulation is sometimes used in cellular communications to pinpoint the geographic position of a user.
If a sensor is located a user can scan the associated barcode. A configuration page associated with the identified sensor is displayed on the device or to a connected display. The configuration page can list a variety of information related to the sensor. The information can include configuration status (whether an update is required), battery status, transmission history and any other type of information that is useful to a user.
In an embodiment of the invention, a wireless network is not limited to a designated set of sensors. Any number of new devices is connectable. When a new device is connected, a protocol will be utilized for recognizing that a new device is connected. The protocol and communications from a new sensor will include what type of sensor it is and what its capabilities are. The network is enabled to accommodate any type of system. In the event that a device is connected to a network that is new to the system, the system can identify the type of sensor that it is and download any necessary software needed to work with the sensor.
A network is provided which allows forward compatibility. This is similar to USB (Universal Serial Bus) which does not need to know every device that will ever be connected to it. Forward compatibility or upward compatibility (sometimes confused with extensibility) is a compatibility concept for systems design, as is backward compatibility. Forward compatibility aims at the ability of a design to gracefully accept input intended for later versions of itself. The concept can be applied to entire systems, electrical interfaces, telecommunication signals, data communication protocols, file formats, and computer programming languages. A standard supports forward compatibility if older product versions can receive, read, view, play or execute the new standard. The applicability of a forward compatible system with new versions requires not only the respecting of the older version by the designers of the newer version but additionally some agreement on future design features with the design freeze of current versions. The introduction of a forward compatible technology implies that old devices partly can understand data generated by new devices. A base unit in a network can query a new sensor to determine the new sensor's capabilities without manual configuration. This includes the ability of one physical sensor to appear to the network as multiple devices, similar to endpoints in a USB standard.
As is noted above, in the use of systems with wireless sensors, the battery life of batteries in the sensors can be impactful. For instance, in a system with a hundred or more sensors, a short average battery life would result in extensive man-hours locating and replacing batteries. As such, prolonging the battery life in a sensor reduces. Several factors are impactful on battery life. Those factors may include, but are not limited to 1) the amount of time that a sensor is awake to transmit and receive communications (Ta), 2) the transmission power of the wireless radio in a sensor (Pt), 3) the amount of time that it takes for a sensor to transmit and receive data (Tt), and 4) the update frequency of a sensor (TO, which may be set according to preferences of a user. The Ta, Pt, Tt and Tf of a sensor are adjustable parameters.
The transmission power (Pt) required in a sensor is proportional to the distance between two nodes. This may include any objects that may be blocking the transmission path. Blockages naturally increase the required transmission power. The greater the transmission power of a sensor, the greater the drain on a battery per transmission. The time awake (Ta) depends on a number of variables. For instance, a sensor may be being utilized as a repeater. In such a case, the sensor must be awake for longer periods of time in order to receive data from other sensors and then re-transmit that data to a base station. A sensor being used as a repeater can be battery powered or mains powered. Mains power is when an AC adapter is connected to the sensor that draws power from a power line in a building. A sensor being used as a repeater with accessible mains power is optimized differently than a sensor being used as a repeater with only battery power. The time awake (Ta) needs to be balanced with the transmission power (Pt) and the update frequency (TO. A base station will coordinate all network routes and automatically configure a static routing table. In an embodiment of the invention, the amount of energy of a sensor is calculated as follows:
E=[(Pt*Tt)+Ta]*Tf
Energy equals product of the transmission frequency and, the product of the transmission power and the transmission time, plus the sensor awake time.
In an embodiment of the invention, fault detection and fault tolerance are accounted for in a network 700. As noted herein, the network 700 may be optimized for low power consumption as discussed in connection with
In both of the examples of rerouting of signals based on a failure, or tolerance, of sensor S1701, the signals from a single sensor are rerouted. Either sensor S1701 is rerouted to accommodate a weak or blocked signal, for example, or sensor S4704 is rerouted to accommodate a failure of sensor S1701. However, in some cases more than one sensor may be rerouted. As an example, sensor S1701 may indicate that its battery is low and in need of replacement. This may be the same situation mentioned above where sensor S1701 needed to be rerouted to lower the transmission power to conserve its battery life, for example. As noted in this description, a sensor's power consumption may be increased if that sensor acts as a repeater. Accordingly, both sensor S1701 and sensor S4704 may be rerouted to sensor S2702. This saves battery power for sensor S1701 on two fronts. First, sensor S1701 need transmit a shorter distance to sensor S2702 than previously to the base 720. Also, sensor S1701 need no longer act as a repeater for sensor S4704 since sensor S4704 is also rerouted. While the system is generally optimized for low power consumption, such optimization may be dynamic to account for fault detection and tolerance.
To determine if a new route is required for a particular node, as explained above, a simple timeout is used. If a base unit does not receive an expected signal from a sensor, the base unit will determine a different route based on the methods and systems disclosed herein.
Not shown in
The indications to the user of signal quality or estimated batter life, or both, may be communicated by one or more methods. For instance, the sensor being placed by the user may emit an audible tone that varies in frequency (tone) for either signal quality or estimated battery life. The sensor may also emit an audible tone that varies in period proportional to the signal quality or estimated batter life. The sensor may also emit an audible tone that varies in amplitude proportional to signal quality or estimated batter life. The sensor may also be provided with a light, such as an LED, that blinks with a frequency proportional to signal quality or estimated batter life. The sensor may also be provided with a visible light, such as an LED, that changes color in proportion to signal quality or estimated batter life. It is noted that a combination of audible and visual indications may also be provided by a sensor. Or, sensors may be provided with a means to switch from one type of indicator to another type of indicator depending on environmental conditions, such as noisy environments that disallow easy perception of audible tones or very bright environments that may disallow easy perception of visual indicators.
Indicators at a mobile device or at a computer may also be provided to a user. A display on such a device may provide, for example, a graph, bar or line, with relation to time. An audible or visual indicator, such as those mentioned above, may also be emitted from such a device.
In regard to the example locations in
The above example may also be used in connection with a mobile device or computer. The user may place the sensor in “placement mode” as indicated above. The user may then open a sensor page on a mobile device or computer. The user will move the sensor around in a trial and error manner described above. The mobile device will display a real-time signal quality or estimated batter life indicator. The sensor may be sensor S1 and may be using sensor S2 as a repeater. The display on the mobile device or computer may show the signal quality or estimated batter life of the current sensor, S1, as well as the signal quality or estimated batter life of the sensor, S2, being used as a repeater.
It is understood that all of the example sensors, S1-S14, may not be actually placed in a real life scenario. One or more, or all of the sensors may be placed as shown. For example, sensors S14 and S11 may be placed first and may provide sufficient coverage for a portion of the shown area 1000. Second level sensors such as S9 and S10 may then be placed using the first placed sensors as repeaters, or may communicate directly with the base unit 1020. Successively, sensors may be placed until sufficient coverage of an area is accomplished. The communications scheme of the sensors, S1-S14, in the event that all are placed as shown, may result in a time schedule and routing scheme as shown in
The foregoing description is considered as illustrative of the principles of the invention. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and process shown and described above. Accordingly, resort may be made to all suitable modifications and equivalents that fall within the scope of the invention. The words “comprise,” “comprises,” “comprising,” “include,” “including,” and “includes” when used in this specification are intended to specify the presence of stated features, integers, components, or steps, but they do not preclude the presence or addition of one or more other features, integers, components, steps, or groups thereof.
| Number | Date | Country | |
|---|---|---|---|
| 61968914 | Mar 2014 | US |
