Patent Application
20120214411
1. Field
The present invention relates generally to near field communication and, more particularly, to power saving within such an environment.
2. Description of Related Art
The use of portable electronic devices and mobile communication devices has increased dramatically in recent years. Moreover, the demand for mobile devices that allow users to conduct contactless transactions is increasing. Near Field Communication technology (NFC) enables mobile devices to act as an electronic data transaction device. As one example, NFC can be used to perform contactless financial transactions such as those requiring a credit card. The user may select credit card information stored in the mobile device and perform contactless payments in a quick way by “tapping” or “waving” the mobile device in front of a contactless reader terminal. A reader terminal can read the credit card information and process a financial transaction. NFC can be coupled with an UICC (Universal Integrated Circuit Card) chip card used in mobile terminals in GSM (Global System for Mobile), UMTS (Universal Mobile Telecommunications System) or other networks to provide contactless payment transactions.
NFC technology on the other hand is being used in a wide array of applications including “fast-lane” payment at gas stations and supermarkets, for transit payments, and more. The mobile phone industry including governments have also moved forward in delivering services such as credit-card payments, Mobile Time Reporting, Smart Parking, Smart Theater for tickets with smart posters for information distribution, Information Tags in Restaurants for payment and ordering using hand-held devices, enabling Buses and Bus Stops with information and tickets, etc. This technology is already being used for services such as mobile ticketing and used to replace plastic credit and debit cards in consumers' pockets around the world.
One shortcoming, however, is unnecessary power consumption resulting in excessive battery drain, which is especially more sever in platforms that wish to enable automatic (i.e., non-user initiated) transactions requiring the NFC to perform “background polling”. The market desires as small an antenna as possible which results in a need to increase the antenna drive power and hence, power consumption, to achieve a desired link performance. Also, legacy technology standards result in relatively long activity thereby further increasing power consumption. Some solutions in the marketplace implement a “perceived” background polling each time a phone's display is turned on. There remains the need however for an improved method of reducing power regardless of whether the device implements perceived background polling or not.
Embodiments of the present invention relate to a system and method for background polling for objects that can participate in near filed communication transactions. A system for detecting the presence of a near filed communication object includes a radiator configured to radiate a magnetic field from a near field communication reader device; a detector configured to detect a loading effect on the magnetic field caused by the near filed communication object; and a decision circuit configured to determine that the near field communication object is present based on the detected loading effect. In addition, a second order algorithm can be implemented to further distinguish the presence of NFC devices in the vicinity from other loading artifacts. Only once the presence of a nearby NFC object is detected will higher power-consuming communications take place. Accordingly a power-sensitive background polling feature can be implement within the NFC architecture.
It is understood that other embodiments of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein it is shown and described only various embodiments of the invention by way of illustration. As will be realized, the invention is capable of other and different embodiments and its several details are capable of modification in various other respects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive.
Various aspects of embodiments of the invention are illustrated by way of example, and not by way of limitation, in the accompanying drawings, wherein:
The detailed description set forth below in connection with the appended drawings is intended as a description of various embodiments of the invention and is not intended to represent the only embodiments in which the invention may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring the concepts of the invention.
In the description that follows embodiments of the present invention are explained with reference to NFC technology. However, other contactless proximity/vicinity technologies are encompassed as well such as those complying with ISO 14443, JIS 6319-4, ISO15693, ISO18092/ECMA-340, for example. Also, the power saving benefit of the present invention is highlighted in some places. In addition, there is also coexistence benefits that are derived from embodiments of the present invention. Within multi-radio technology devices (e.g., integration of Bluetooth, GPS, WiFi, NFC, etc) the reduced NFC activity duty-cycle allows a reduced interference period and allows scheduling based solutions.
When an alternating current circulates in a coil of wire, two types of fields are produced: radiating and non-radiating. If the wire is small compared to the wavelength, very little energy can propagate away from the inductor in the radiating field, and the movement of energy is predominantly contained in the non-radiating field, called the reactive near field. It is called this because unless some of the energy is taken of the field by loading it, the energy is re-absorbed by the source instead of radiating out to free space. It is the reactive near field that is used by NFC.
A way to load the reactive near field is to place another inductor in proximity to the field so that the changing magnetic flux passes through the other inductor, causing a terminal voltage. The amount of coupling between the two inductors that is achieved is called the mutual inductance of the inductor pair. Instead of using this phenomenon to provide a protocol communication that energizes the other NFC device and communicating with it. (i.e., the high power consumption technique of
The device 300 includes an NFC modem 302 which is the physical structure used to facilitate communication. However, the signals are evaluated and processed by an NFC core 304 that converts the physical radio signals into meaningful data which is transmitted or received by the device 300. With reference to embodiments of the present invention, the NFC core 304 includes one functional block labeled the NFC probe 306 and one functional block labeled NFC poll 308. The general communications and other features that are used to implement the NFC protocol are depicted as the functional block labeled NFC communications 310.
The NFC poll 308 block performs the above-described polling functionality that determines the capabilities of a nearby NFC device so that communications or a transaction can occur. The NFC probe 306 block is used to implement the probing timeline depicted in
One of ordinary skill will recognize that there are functionally equivalent ways of determining the load of a nearby inductor on the magnetic field radiated by the mobile device 300. For example, the voltage across the radiating conductor can be measured at two different frequencies to determine if an object nearby is radiating at that frequency. A lower relative voltage at one frequency will indicate the presence of an inductor nearby radiating at that frequency as well. Also, the resonant frequency peak will shift somewhat when a similar resonant circuit is nearby. Additionally, the probe element could also operate so as to sense the change in current drawn from the NFC device by its antenna and its corresponding matching circuit because with NFC devices in the vicinity, this current will change. Thus, if the radiating peak shifts downward slightly from 13.56 MHz, then that likely indicates that an NFC object 312 is nearby.
In step 404, if a nearby object is detected to be present, then step 406 is performed which initiates the standard polling steps in the NFC protocol. If, however, no nearby object was detected, then the probing repeats itself after a predetermined time period (e.g., 300 mS).
Once the polling steps take place, in step 406, the two NFC devices can communicate and thereby accomplish some NFC transaction, in step 408.
The previous description is provided to enable any person skilled in the art to practice the various embodiments described herein. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments. Thus, the claims are not intended to be limited to the embodiments shown herein, but are to be accorded the full scope consistent with each claim's language, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” All structural and functional equivalents to the elements of the various embodiments described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. Also, the term “exemplary” is meant to indicate that some information is being provided as an example only as is not intended to mean that that information is somehow special or preferred. No claim element is to be construed under the provisions of 35 U.S.C. §112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.”
