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Decreased Power Consumption of Location Systems

IP.com Disclosure Number: IPCOM000244561D
Publication Date: 2015-Dec-21
Document File: 2 page(s) / 107K

Publishing Venue

The IP.com Prior Art Database

Abstract

Location sensors have been designed to accommodate tens of thousands of tags as it has been thought that eventually systems would scale to a plethora of inexpensive tags and few sensors. The sensors were made to be sophisticated to enable the tag technology cost to be driven down with volume. To that end, tags blink randomly and sensors are always-on and listening.

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Decreased Power Consumption of Location Systems

     A significant impediment to sales of location systems is the cost of installing the sensors themselves. Specifically for outdoors, the installation of the wires are more expensive then the sensors as it typically requires trenching which is both costly and interrupts customer business during the trenching process. Wireless LANs and wireless time synchronization have been deployed; however, a power source is still required. Solar power is another option for powering the sensors, but the hardware is often more expensive than the sensors themselves given that the current sensor power consumption is around 11 watts.

     Location sensors have been designed to accommodate tens of thousands of tags as it has been thought that eventually systems would scale to a plethora of inexpensive tags and few sensors. The sensors were made to be sophisticated to enable the tag technology cost to be driven down with volume. To that end, tags blink randomly and sensors are always-on and listening.

     Another design point for location systems is to be able to achieve 99% probability of location whenever a tag blinked. This, in turn, drove a 99.7% probability of detection at each sensor. Ultimately, this design point implies that, on average, no more than 10% to 20% of airtime (referred to as capacity) is consumed by tag blinks. Specifically, in some cases, the transmission time of a typical tag may be on the order of 1 millisecond. At 10% to 20% capacity, no more than 100 to 200 blinks per second would be allowed at any site. Generally, when a tag wakes up to blink it actually transmits 4 individual messages, so that 10%-20% capacity means no more than 25 to 50 tags per second waking up and blinking. At an average of 4 minutes between each blink, up to 12,000 tags per sensor area can be accommodated.

     Some large sites have up to 40,000 tags and the systems can function appropriately. However, there are many more potential sites with fewer than 1,000 tags, with capacity under 1%, on the entire facility that are difficult to sell due to the cost of running wires or solar power. For these types of sites (e.g., tractor trailer yards), a method to significantly reduce power consumption of each sensor would enable a less costly solar solution and open the door to the sale.

     Through various means, proposed herein are methods of reducing power consumption of location systems. In some embodiments, matching the duty cycle of the sensor with that of the tag can provide a significant benefit. For example, if a sensor were to turn on precisely at the time of a known tag transmission and shutdown at the end of the transmission, the average power consumption would be 1%-10% of what current consumption is: e.g. 110mW-1.1W instead of 11W. Knowing the precise time of transmission is a technological hurdle in this embodiment.

     Embodiments of the present invention include multiple proposed system architectures and/or enhancements to...