Power Management for an Active RFID Tag in Credit Card Form Factor

Abstract

A system and method manages power in a dual frequency Active Radio Frequency Identification (RFID) transponder having a form factor substantially conforming to a credit card or smaller. The transponder may be conveniently carried in a customer's wallet, pocket, or purse. The transponder generally operates in a listen-only non-transmitting sleep mode in a low-power state. When entering a retail establishment, the transponder may receive an activation signal while operating in the sleep mode that activates the transponder and causes it to operate in a beacon mode. While in the beacon mode, the transponder transmits an identifier signal identifying the transponder. The identifier information may be used by a customer relationship management system within the retail establishment to provide a variety of customer management service. Subsequently, the transponder returns to the sleep mode, thereby enabling high battery life.

Description

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61/430,447 entitled “Reader Network System for Implementing Presence Management in a Physical Retail Environment” to Rolin, et al., filed Jan. 6, 2011, U.S. Provisional Application No. 61/430,450, entitled “PCB Design and Card Assembly for an Active RFID Tag in Credit Card Form Factor” to Rolin, et al., filed Jan. 6, 2011, and U.S. Provisional Application No. 61/430,451, entitled “Power Management for an Active RFID Tag in Credit Card Form Factor,” to Rolin, et al., filed Jan. 6, 2011, the contents of which are all incorporated by reference herein.

BACKGROUND

1. Field of Art

The invention generally relates to customer relationship management and more specifically to a customer relationship management in a physical retail environment.

2. Description of the Related Art

Modern society has created a plethora of ways to provide goods and services to customers. However, physical locations continue to be the predominant forums preferred by customers. Physical locations include brick and mortar establishments, i.e., those places a customer can physically go to purchase goods, receive services, etc. Whatever the type of business, be it retail stores, banks, restaurants, patio cafes, or any other type business, customers prefer to interact directly with the providers of the goods and services.

From a perspective of customer service at brick and mortar establishments, present systems lacks a mechanism to effectively service the customer based on his profile, preferences and transaction history, or at best these mechanisms are very ad-hoc and un-automated. Although basic incentive systems are commonly used, these incentives are very limited in their effectiveness because they are offered at the end of the transaction, which is too late. Furthermore, present brick and mortar locations lack the technology to track and service customers within the retail establishment.

SUMMARY

A dual frequency Active Radio Frequency Identification (RFID) transponder performs power management to achieve a battery lifetime of two years or more. The transponder is in a form factor substantially conforming to a credit card or smaller. The transponder first operates in a sleep mode that comprises a listen-only non-transmitting state of the transponder. During the sleep mode, the transponder receives an activation signal from an activator at a distance of at least 10 feet from the transponder. The activation signal activates the transponder from the sleep mode and controls the transponder to operate in a beacon mode. While operating in the beacon mode, the transponder transmits an identifier signal identifying the transponder. The identifier signal is detectable at a range of at least 20 feet from the transponder. Responsive to ending operation in the beacon mode the transponder re-enters the sleep mode.

The features and advantages described in the specification are not all inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification, and claims. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a block diagram of an In-Store Ad Network in accordance with one embodiment.

FIG. 2 is a block diagram of a store-corporate application communication system in accordance with one embodiment.

FIG. 3 is a timing diagram of a card life cycle in accordance with one embodiment.

FIG. 4 is a timing diagram of a card activation process in accordance with one embodiment.

FIG. 5 is a timing diagram of Normal Mode operation of a card in accordance with one embodiment.

FIG. 6 is a diagram illustrating an activator transmission data structure in accordance with one embodiment.

FIG. 7 is a diagram illustrating a card transmission data structure in a Beacon Mode, in accordance with one embodiment.

FIG. 8 is a timing diagram illustrating Boostrap Mode operation of a card in accordance with one embodiment.

FIG. 9 is a timing diagram illustrating Transition Mode operation of a card in accordance with one embodiment.

FIG. 10 is a timing diagram illustrating Boostrap Mode current consumption in accordance with one embodiment.

FIG. 11 is a timing diagram illustrating Transition Mode current consumption in accordance with one embodiment.

FIG. 12 is a timing diagram illustrating Normal Mode current consumption in accordance with one embodiment.

The figures depict various embodiments of the present invention for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the invention described herein.

DETAILED DESCRIPTION

Overview

A Digital In-Store Ad Network system can be used in retail environments to detect the localized presence of customers in real time. The Digital In-Store Ad Network uses this presence knowledge of customers to deliver relevant and timely offers to those customers while they are in the retail environment. This optimizes the customer's purchasing ability, increases store revenues, and increases customer loyalty. The Digital In-Store Ad Network collects and analyzes customer shopping pattern data and provides it to merchants and brand companies so they can easily optimize advertising effectiveness.

The Digital In-Store Ad Network comprises hardware and software platforms. The following description describes the hardware and operation of the Reader network installed in a store implementing the Digital In-Store Ad Network system.

Terms & Descriptions Used Herein

The following table (Table 1) provides example descriptions for terms used in the following sections. The table is intended to improve readability and clarity of the description of embodiments that follow. The terms below are not necessarily limited to the particular example definitions provided in table 1, but rather should be interpreted in view of the entire description (which may vary in between different described embodiments) and in view of their usage in the claims.

Term              Description
Activation        Process of activating a Card (causes the Beacon State)
Activation        Time period immediately following Beacon Mode expiration during which
Holdoff           Card activation is disabled.
Activation Range  Maximum separation (distance) between an Activator and Card at which
                  the Card will be successfully activated.
Activation Signal RF transmission of an Activator used to turn on (activate) Cards. The
                  activation signal contains data used by the Card to validate the activation
                  signal and to set Card behavioral options.
Activation Zone   The physical volume within which a Card will be activated. Typically
                  located at a Store or business entrance and/or exit.
Activator         Hardware device that wirelessly activates Cards upon arrival at an enabled
                  retailer.
Active RFID       RFID card that uses an internal battery for enhanced performance
Card
Anticollision     Method for avoiding or minimizing the collision of RF transmissions by
                  more than one source occupying the same frequency and physical space so
                  that each individual signal can be distinguished by a receiving device.
Base Station      Device that wirelessly receives Card read information from Readers and
                  communicates this information to a host computer to facilitate the
                  generation of offers to Cardholders through the Software Platform.
Beacon Mode       Operating state of a Card that commences upon activation. The Card
                  periodically transmits a unique ID for detection by Reader hardware.
Brand Company     The branding manufacturer that sells products in stores (a.k.a. “Brand”).
Card              Hardware device carried by a person; contains electronics to practice the
                  embodiments described. Generally has the form of a credit card.
Cardholder        Person (Consumer) who has opted into the Digital In-Store Ad Network
                  and who possesses a Card.
Collision         Simultaneous RF transmissions by more than one source occupying the
                  same frequency and physical space, which cause a receiving device to be
                  unable to distinguish the individual signals. Also referred to as “data
                  collision”.
Consumer          Individual that shops and/or purchases products in a store (becomes a
                  Cardholder upon opting-in to carry a Card).
Deep Sleep        Normal operating state of a Card in which power consumption is very low
                  and the Card does not transmit information to Readers.
Demodulation      Process of separating a modulated signal into component signals, such as
                  an RF signal (‘carrier’) and a data signal.
Digital In-Store  hardware/software system used that provides relevant offers to
Ad Network        participating Consumers while they are physically at a participating retail
                  environment.
Hotspot           Small area in a store containing Reader(s) that detect Cards within that
                  area.
ID                A numerical value assigned to and stored within each Card; the value being
                  unique to each Cardholder. The ID Number is wirelessly transmitted by a
                  Card when in the Beacon Mode for reception by Readers. Also referred to
                  as “Card ID” or “ID number”.
Listen            A state within the Sleep Mode during which the Card “listens” for
                  activation signals. Cards can be activated only when in the Listen state.
Merchant          Business in which physical sales or services are provided to a consumer.
                  Generally applies to businesses which have implemented the Digital In-
                  Store Ad Network. Also referred to store, retailer, etc.
Modulation        Process of changing one signal as a function of another signal. Often used
                  by transmitting devices to add information (data) onto an RF signal,
                  thereby ‘carrying’ the data via electromagnetic wave to a remote receiving
                  device for subsequent data extraction.
RF                Radio frequency.
RF Signal         Radio frequency energy. May be modulated to carry information (data) to
                  a receiving device. May refer to an electromagnetic wave propagating in
                  space in wireless communication systems.
RF Transmission   Generation of an RF signal. Often used to cause electromagnetic wave
                  propagation from an antenna through space in wireless communication
                  systems.
RFID              Radio Frequency Identification
Read              The process or result of wirelessly detecting and successfully decoding a
                  Card ID.
Reader            Hardware device that wirelessly receives Card IDs and relays this
                  information to the Base Station.
Read Range        Maximum separation (distance) between RF transmitting and receiving
                  devices (e.g., Card and Reader, respectively) at which the transmitted RF
                  signal can be successfully read.
Read Zone         The area within which a hotspot Reader can reliably read activated Cards.
Read Volume       General term referring to read range in 3-dimensional space. Read range
                  may vary with direction, device orientation, and presence of physical
                  objects, so read volume is not necessarily uniform or symmetrical.
Retailer          See merchant
Session Metrics   Data that describes a Cardholder's shopping history within a participating
                  retailer. This can include the time spent in the store, in each department,
                  responses to ads, and purchases.
Store             See merchant
Wake-Up           The event of Card activation, which marks the transition from a low-power
                  sleep state in the Card to a higher power activity state.
6LoWPAN           A wireless networking standard for low power wireless personal area
                  networks.

Introduction

FIG. 1 provides a high-level illustration of an embodiment of a Digital In-Store Ad Network. The Digital In-Store Ad Network is a hardware-software system that provides an integrated direct marketing solution that benefits participating product manufacturers, merchants, and consumers alike. Consumers benefit because they can receive private, relevant, and timely offers from product manufacturers and merchants while physically in the retail environment. Product manufacturers benefit by having an opportunity to market directly to consumers based upon interests they shared when opting-in to the system and enhanced with the consumer's shopping and purchasing history. Merchants benefit by better serving the needs of their customers, thereby improving customer loyalty and increasing sales. Revenue is collected from advertisers as a function of a) ads served, b) customer response to those ads, and c) offer redemption at the point of sale.

The hardware aspect of the Digital In-Store Ad Network is comprised of several distinct physical elements, each having specific functions. The hardware can be grouped into two general categories:

• • RFID-based loyalty/credit cards carried by participating consumers (Cardholders). Cards have the form factor of thin plastic credit cards, and can be left in the Cardholder's wallet, purse, or pocket during use—physical Card presentation or manipulation is not required. In FIG. 1, individual Cardholders 102 are differentiated from one another by letter. Other consumers (non-Cardholders) 104 have neither a letter nor a “card” symbol near their shoulder.
  • Hardware devices of several types are installed in the retail environment to wirelessly activate and read Novitaz RFID Cards; thereby detecting the presence of participating Cardholders. Furthermore, locations of Cardholders 102 within the store (e.g., department or product display) is determined by the spatial distribution of Readers 106 throughout the store. This hardware system delivers store presence of Cardholders 102 and activity data via the Internet 110 to secure servers that run the Software Platform 112. These hardware devices are known as Activators 108, Readers 106, and Base Stations 114; and are shown in FIG. 1.

The Software Platform 112 collects and analyzes store activity data of Cardholders 102 and then serves relevant offers to individual Cardholders 102 on their mobile phones while they are physically in a specific store 100. The Software Platform 112 is shown outside the store 100 in FIG. 1. The Software Platform 112 can match offers to the specific department or product display that the Cardholder 102 is visiting at the time. The Software Platform 112 contains many functions, which include:

• • A configurable marketing campaign tool for advertisers and merchants.
  • A Rules Engine to convert in-store shopping metrics into knowledge services, which are used by advertisers and merchants analyze the effectiveness of offers so they can maximize revenues and customer loyalty.
  • A Cardholder portal for opting-in/out, entering or changing personal data, preferences, etc.

Hardware Building Blocks of Digital In-Store Ad Network System

Consumers that opt-in are issued active RFID Cards, and become Cardholders 102. The Card contains an electronic system with antennae for wireless communication with hardware devices within an enabled store (“Store”) 100. The Card also contains an internal battery that extends the wireless communication distance to meet the requirements of the application. The circuitry within the Card is permanently encoded with an ID number that is unique to each Card (there is no ID duplication amongst the Card and Cardholder population). The ID is an abstract number and no personally-identifiable Cardholder data resides on the Card.

An important feature of the Card is its thin plastic credit card form factor, making it quite convenient and natural to carry. The Card can be produced with merchant-specific graphics so it can be offered as a loyalty card to its customers.

Another feature is that Cardholders 102 only bring their Card with them when they shop at a Store 100. Hardware is designed such that the Card can be left in the wallet, purse, pocket, etc. of a Cardholder 102—it does not have to be removed, manipulated, or presented in the store for the system to function properly. No special effort is required on the part of the Cardholder 102—they simply walk into the Store 100 and shop in a normal manner.

When a Cardholder 102 opts-in to a sponsored program, their individual Card ID Number is associated with their account in the Software Platform 112. This information is known only to the Software Platform 112 and is used to facilitate the serving of offers to individual Cardholders 102 and for collecting shopping session metrics for participating brand companies and retailers. Other than their name and cellular telephone number, Cardholders 102 provide as much or as little additional information based upon the services they wish to receive and/or their individual disclosure preferences. Additional information, if provided, can include things such as product preferences, brand preferences, etc.; and can be used to provide even more relevant offers to Cardholders 102 while they are in a participating retail establishment.

The Software Platform 112 sends relevant offers are sent to a Cardholder's mobile phone, either as a text or SMS message. Offers sent to a Cardholder's mobile phone include product information and “coupon” codes that can be used for redemption at the point of sale.

The terms “store”, “merchant”, and “retailer” are used interchangeably in this description. These terms are not meant to limit the venue or business type in which the system can be used. Others include, but are not limited to, restaurants, entertainment, service businesses, etc.

An enabled Store 100 contains several distinct installed hardware devices, referred to as Activator 108, Reader 106, and Base Station 114. The basic function of each device and its role in the Digital In-Store Ad Network system is illustrated in FIG. 1 and described below. In general, the descriptions include the presence of at least one Card (i.e., Cardholder 102).

Activator

Activators 108 are typically located only at store entrances and/or egresses, so a Store 100 may have one or more Activators 108, depending upon the size and quantity of entrance and egress areas.

The Activator 108 wirelessly “turns on” (activates) a Cardholder's Card when they enter a Store 100, causing the Card to transmit its ID number via an RF (radio frequency) signal to receiving devices (Readers 106) distributed throughout the store.

The Activator 108 transmits a Card activation signal, which is a low frequency RF signal modulated with specific data; represented by arrow waves 1 pointing away from the Activator 108 in FIG. 1. A Card that receives and decodes the Activator signal 1 is triggered, or “activated”, and begins to transmit its unique ID, which is represented by a arrow wave 2 pointing away from activated Cards. Activators 108 repeatedly transmit the activation signal 1 in order to trigger Cards entering the Store throughout the day. Activation signals 1 are typically transmitted in multiple directions, or axes, to assure reliable Card activation independent of Card orientation as they enter the Store 100 (though single-axis transmission is also possible). Once activated, Cards periodically transmit their IDs 2 for a finite period of time, and can therefore be read multiple times during the Cardholder's visit to the Store 100 without requiring re-activation.

Specific Activator operating modes & parameters can be configured via an Ethernet (wired) interface (not shown). Some configuration settings can also be selected on a PC and sent to the Activator 108 by the Base Station 114 via a 6LoWPAN wireless communication network (wave arrows 3). Other wireless and/or wired communication methods/standards could be used if desired.

Reader

At least one Reader 106 is installed in order to detect the presence of Cardholders 102 in the Store. Multiple Readers 106 can be installed throughout the Store in order to detect the presence of individual Cardholders 102 within specific sections of the Store.

A Reader 106 receives and decodes (“reads”) the ID 2 transmitted by activated Card(s) that are within its “read range”. The effective read zone of a Reader 106 is referred to as a “hotspot”. As illustrated in FIG. 1 Error! Reference source not found., the read range of a Reader 106 is sufficient to read activated Cards that are physically within individual Store departments 120 (Departments 1, 3, 4, and 5). Readers can be desensitized to restrict the read zone to a specific area, as shown in Department 2. This, for example, allows presence of a Cardholder 102 within a brand-centric display area to be known so the brand company can send relevant offers to Cardholders 102 when they are in their display area.

Though not shown, Readers 106 may be positioned near Store entrance areas in order to detect presence of Cardholders 102 at the earliest opportunity, before they travel to a store department 120. Readers 106 do not communicate information to Cards in one embodiment.

Readers 106 do not communicate with Activators 108 in one embodiment, though it is technically feasible and may have value in some systems.

Readers 106 wirelessly communicate Card read data to the Base Station 114 within the Store 100 via a 6LoWPAN wireless communication network (wave arrows 4). Specific Reader 106 operating modes & parameters can be configured via an Ethernet (wired) interface (not shown). Some configuration settings can also be selected on a PC and sent to the Reader by the Base Station via a 6LoWPAN wireless communication network (wave arrows 3). Other wireless and/or wired communication methods/standards could be used if desired.

Base Station

A single Base Station 114 is typically used in an enabled store. It wirelessly collects data (wave arrows 4) from all Readers 106 installed in the store. The Base Station 114 also sends configuration instructions 3 to Readers 106 and Activators.

Base Stations 114 wirelessly communicate with Readers 106 and Activators 108 within the Store 100 via a 6LoWPAN wireless communication network, as represented by the arrow waves 3 in FIG. 1 Error! Reference source not found. Other wireless and/or wired communication methods/standards could be used if desired. Base Stations are also capable of communication via an Ethernet (wired) interface (not shown).

The Base Station 114 does not communicate with Cards in one embodiment.

The Base Station 114 connects via Ethernet to a PC running software for local campaign management at the store level. The PC relays session metrics data via the Internet to the Software Platform 112, which in turn serves offers to Cardholders 102 and makes this data accessible to participating brand companies and merchants.

Store-Corporate Interface

An example of a Store-Corporate Interface is illustrated in FIG. 2. A Store Appliance 202 running a local software application connects to the Base Station 114, and is used to relay session metrics data to servers, which processes the data and makes it available to participating brand companies and merchants. The Store Appliance 202 is also used for Reader 106 and Activator 108 configuration, and provides an interface for store personnel.

The Store Appliance 202 runs the identification and store-engagement applications of the Digital In-Store Ad Network and communicates with the corporate appliance. The in-store session metrics are transferred from the store appliance to the corporate appliance; and the engagement plans and offers are disseminated from the corporate appliance.

Card

While not actually installed Store hardware, the Card is a hardware element of the System. It is a portable wireless identification device packaged in a credit card form factor that is carried by the Cardholder 102 to identify them upon entry to a participating Store 100.

The Card contains a sensitive antenna and receiver system designed to selectively detect low frequency RF transmissions from the Activator. When the Card is in the vicinity of the Activator 108 (Store entrance) and detects an activation signal 1, it turns on (activates) and begins transmitting its unique ID 2 at a high RF frequency through a different antenna. The Card periodically re-transmits its unique ID 2 for a finite period of time, which, for example, can approximate the typical time Cardholders 102 spend in the Store 100. Cardholder 102 presence within specific Store areas is detected by the hotspot Reader 106 in each area and then communicated to the Software Platform 112 via the Base Station 114 within the Store 100. The Software Platform 112 uses this information to serve timely and relevant offers to the Cardholder 102 and to collect Cardholder 102 shopping pattern data (“session metrics”). The Card may be re-activated upon the Cardholder's next entry into a participating Store 100.

The Card contains a thin battery that powers the receiver and transmitter circuitry to achieve the activation range and read range needed for this application. Special methods are employed in the Card and the System to minimize battery drain, thereby maximizing Card life.

Card communication pathways are wireless only in one embodiment; there is no wired interface. In one embodiment, the Card receives information only from Activators 108, and sends information only to Readers 106. The Card utilizes one data structure and frequency (125 kHz) for the link with Activators, and a different data structure and frequency (433.92 MHz) for the link with Readers. The dual-frequency approach and choice of frequencies facilitate optimal performance for Card activation and for Card reading.

The Card does not communicate with Base Stations in one embodiment.

Operating Frequencies

The Activator 108 transmits a low RF frequency (125 kHz) magnetic field, which can be easily detected by the low-frequency (LF) receiving system of the Card. This frequency was chosen to maximize activation signal detection even when the Card is positioned against the Cardholder's body or buried in the Cardholder's purse surrounded by metal objects and fluids (which significantly impact performance at very high frequencies such as UHF (e.g., 900 MHz)).

Card reply transmissions, however, occur at 433.92 MHz—a much higher frequency than the activation signal. This high frequency will carry farther than a low frequency signal will. 433.92 MHz is less sensitive to the attenuating effects of metal or liquid objects positioned near the Card compared to 900 MHz. Furthermore, the battery-powered transmitter in the Card boosts the power of the Card ID transmission to overcome the attenuating effects of any objects that may be in close proximity to the Card, increasing read reliability in the reader network.

The large frequency separation enables performance optimization of receive and transmit functions within the Card without adverse interactions between the two subsystems. Finally, the large frequency separation between Activator 108 transmission and the Reader 106 receive band prevents interference between them—a Reader 106 positioned near an Activator 108 will not be overwhelmed by the Activator 108 transmissions, allowing it to clearly receive Card transmissions.

Reader data is sent to the Base Station 114 at a third carrier frequency of 2.4 GHz, making this communication link immune to Activator and Card transmissions. This same 2.4 GHz radio link is also used by the Base Station 114, Reader 106, and Activator 108 for configuration purposes.

System Operation

Unlike passive RFID cards, the Card contains a battery to facilitate long system communication distances. The battery powers detection circuitry to increase the sensitivity to Activator RF transmissions, enabling an activation range (distance) of several meters. The battery also powers circuitry that boosts Card transmission signal, which enables a read range of several meters (usually greater than activation range). The battery also powers circuitry that provides enhanced functionality not possible with passive RFID tag technology. The battery-powered Card technology, multi-frequency design, and overall system operation deliver the functionality and range required of the Digital In-Store Ad Network application.

Only a small and very thin battery will fit in a credit card form factor, significantly limiting battery energy storage capacity. Card longevity is an important characteristic that is a direct function of battery life, so the Card/Activators 108/Readers 106 are carefully designed to minimize power consumption and achieve a battery life of 2+ years.

FIG. 3 shows the different phases comprising the life cycle of a Card from its manufacture to its end of life (EOL) 314. Card life begins at time T_o when the battery is connected 302 to the Card electronics assembly 306 during the manufacturing process 304. When this occurs, the Card automatically begins operations to guarantee proper initialization and allow testing to occur during the remainder of the manufacturing process (Bootstrap 308 and Transition Modes 310). These processes are controlled by hardware and firmware that resides in the Card electronics assembly, and last for approximately 12 hours. The Card automatically transitions from each mode to the next, and the Card spends virtually its entire operational life in the Normal Mode 312. Card life (t_uFE) ends when the battery is discharged to a voltage below the minimum operational threshold of the Card electronics (battery depleted 322).

There are two operational sub-modes of the Normal Mode 312 shown in FIG. 3 Error! Reference source not found.; the Sleep Mode 316 (S) and the Beacon Mode 318 (B). The Card is naturally in the Sleep Mode 316, which is a very low power consumption state, and only leaves the Sleep Mode 316 when “woken up” by an Activator 320 (symbolized by the circled A with an arrow). The Card switches to the Beacon Mode 318 upon activation for a fixed period of time, during which the Card periodically transmits its ID for reception by Reader(s). At the end of this relatively short fixed period of time, the Card automatically reverts to the Sleep Mode 316 and remains there until it receives another activation signal during a future Store visit.

FIG. 4 illustrates the Card activation process. The physical Store 100 is shown at the top of the figure (side view). The Card is initially outside the Store 100 and is moving in a path through the entrance and into the Store 100. The Card is exposed to the signal transmitted by the Activator 108 while in the entrance area, or Activation Zone 402, defined by the intersection of the angled dashed lines from the Activator 108 and the movement path of the Card.

Electrical signals as a function of time are represented below the Store diagram. Activator transmission packets 404 are shown to illustrate the time-space nature of the activation signal in the Store entrance. The Activator 108 transmits a single activation data packet every 33 ms (T_AP), with no signal transmission in between packets. The duration of each Activator transmission is approximately 20 ms (t_AT). The activation repetition rate is sufficiently high to provide several activation packets per Card as it passes through the entrance area of the Store 100, increasing activation reliability. This also ensures that all Cards entering the Store 100 throughout the day are reliably activated.

As the Card approaches the Store entrance, the Card begins to pick up the activation signal, as shown by the Activation Signal Strength 406 in Card waveform. The activation signal strength 406 received by the Card increases as the Card moves closer to the Activator 108. The received signal strength is greatest when the Card is well within the Activation Zone 402, and then begins to decrease as the Card moves out of the Activation Zone 402 and into the Store 100. The horizontal dashed line intersecting the received signal strength represents the minimum amplitude required by the Card to accurately receive and validate the activation signal. The received packets numbered 1, 2, 3, and 4 all have sufficient strength to be properly detected by the Card.

Packet number 1 is the first ‘valid’ activation packet received by the Card. The Card Mode 408 waveform illustrates the Card being activated at the end of Activator packet number 1, causing the Card to switch from the Sleep Mode 316 to the Beacon Mode 318. Activation triggers the random time delay t_BD1, after which the Card transmits one ID packet for receipt by Reader(s) 106. At the end of the first Card ID transmission, the Card switches to a low power state and waits for a relatively long fixed time delay t_BS, followed by a shorter random time delay t_BD2, and then transmits another ID packet. The line between each Card transmission is broken to indicate a different time scale—the magnitude of delay between Card transmissions is much greater than the duration of an individual Card ID transmission (t_BT). Card ID transmission takes about 14 ms, while the total delay between Card ID transmissions is on the order of 13 seconds. The Card continues to repeat ID transmissions with a different random delay t_BDn preceding each ID packet transmission, until the Beacon Mode duration expires (not shown). The Beacon Mode 318 duration is a fixed time, and can be set to a specific length by the Activator 108, thereby allowing customized behavior as a function of the type of store and typical Cardholder 102 shopping habits.

Greater detail of operation in the Normal Mode 312 is shown in FIG. 5. The Sleep Mode 316 is composed of constantly repeating Sleep Frames (SF), which last for a fixed period of time, tSF (227.5 ms). Cards do not transmit when in the Sleep Mode 316. Each Sleep Frame is composed of two states; the longest duration state being called Deep Sleep. The Deep Sleep state is the lowest power state, and lasts for the fixed duration t_SD (182 ms). When the Deep Sleep timer expires, the Card switches to the Listen state, which lasts for the fixed duration t_SL (45.5 ms). During the Listen state, the Card power consumption increases slightly to “listen” for activation signals. At the end of the Listen state, the Card automatically reverts to the Deep Sleep state. The Deep Sleep/Listen cycle repeats continuously until the Card detects a valid activation signal during a Listen state period. When a valid activation signal is detected, the Card switches to the Beacon Mode 318.

Detail B of Error! Reference source not found. FIG. 5 illustrates Card reception of a valid activation signal during the Listen state by the circled A with an arrow. This truncates the Listen state and switches the Card to the Beacon Mode 318, beginning with the Pre-Tx (transmission) Delay; which has a randomly-generated duration. At the end of the Pre-Tx Delay, the Card transmits one ID packet (Tx), which lasts for duration t_BT. Card ID transmission is the highest power state of the Card, but fortunately is quite short in duration (−14 ms). At the end of the Card ID transmission, the Card switches to a much lower power, fixed-duration, quiet state (Beacon Sleep), t_BS. At the end of the Beacon Sleep period, a new random Pre-Tx Delay is generated, followed by the second Card ID transmission. Each full sequence composed of a Beacon Sleep period, Pre-Tx Delay, and Card ID transmission is referred to as a Beacon Frame (t_BF). This process repeats until the Beacon Mode duration expires (t_BM). The Beacon Mode 318 duration is a fixed period, but the number of Card transmissions that occur during that time are partially a function of the variable Pre-Tx Delay that occurs before each transmission. The Card cannot be re-activated while in the Beacon Mode 318, which is part of the low-power design of the invention.

At the end of the Beacon Mode 318, the Card returns to the Sleep Mode 316. The Activation Holdoff period, t_AH, begins at this transition, and lasts for a fixed period of time. During the Activation Holdoff, the Card will not re-activate even if in an Activation Zone. This is useful to prevent re-activation if Cardholders linger at a Store entrance, or if they accidentally leave their Card in the Store near an activator (preserves battery life). The Activation Holdoff is a parameter transmitted by the Activator 108, allowing the Activator to set t_AH to suit the type of store and typical Cardholder 102 shopping habits.

Anticollision in the Reader Network

The random Pre-Tx Delay is used as an anticollision mechanism to minimize the chance of simultaneous Card transmissions when two or more Cards enter the Store 100 at the same time. Simultaneous Card transmissions within a hotspot cannot be accurately received by a Reader 106. If only the first Card ID transmission following activation was preceded by the Pre-Tx Delay and then a fixed time spacing was used thereafter to maintain temporal spacing between Cards, it would avoid data collision for only a brief period because those Cardholders 102 diverge from one another and move independently throughout the Store 100. Different combinations of Cardholders 102 will be present in different Hotspots over time, and this is unpredictable. By randomizing the delay before each Card ID transmission, the chance of simultaneous transmissions is minimized. If Card transmissions do overlap within a hotspot, the chances are high that an overlap will not occur in subsequent ID transmissions because each Card will chose a different delay time before transmitting. Variations to this method and other anticollision schemes can be used in the invention, but are not described in this document.

Content of Activator and Card Transmissions

Error! Reference source not found. FIG. 6 details the data contained in the Activator transmission. Each Activator 108 transmission packet begins with a Preamble 602, which is a continuous tone at 125 kHz for a fixed duration (2.56 ms in the present embodiment). The remainder of the Activator transmission is also at 125 kHz (LF carrier), but is ASK modulated with Manchester encoded data summarized by FIG. 6. The Preamble 602 is followed by fixed-content Start Gap 606 and Header fields 608. The Preamble 602, Start Gap 606, and Header fields 608 enable the Card to recognize and synchronize to the activation signal. The Wake-Up ID field 610 follows the Header 608, and is a specific code that must be validated by the Card to confirm it has received a valid activation signal. The Activator ID 612 is a variable data field used to set specific behavioral options in the Card for that activation event. The duration of the Activator transmission, t_AT, is 20.56 ms in the present embodiment.

The Card transmits a 433.92 MHz signal that is ASK modulated with Manchester encoded data as summarized in FIG. 7 Error! Reference source not found. Each ID packet begins with a fixed-data Preamble field 702 followed by a Start Bit 704, which enable the Reader 106 to recognize and synchronize to the Card transmission. Next, the unique Card ID field 706 is transmitted, followed by the Activator ID field 708. The Activator ID field 708 transmitted by the Card is identical the Activator ID received from the Activator 108. The Activator ID 708 can contain a parameter that identifies the specific Activator that activated the Card for use by the System.

The Card transmission packet ends with the CRC field 710, which is calculated based upon the preceding data transmitted, and is subsequently used by the Reader 106 to detect errors in the signal it receives. The duration of the Card transmission, t_BT, is 14.125 ms in the present embodiment. The Card retransmits this packet on a variable time interval that is the sum of the random pre-transmission time delay (10 ms to 1000 ms) and a fixed time (11.6 s). The Card continues to transmit packets at this variable interval for a fixed period of time, t_BM, which can be set as a default value or in accordance with a parameter in the activation signal. The Beacon Mode duration (t_BM) can range from three packets to 2 hours in the present invention. The Card returns to the Sleep Mode when the Beacon Mode times out.

Optimization of Card Behavior for the Reader Network

Stores come in all shapes and sizes, and Cardholder shopping behavior can vary from store to store because of differences in products, services, or environment. For example, Cardholder visit duration in a large department store will likely be longer than a Cardholder visit to a very small store.

To accommodate these and other differences, Card behavior can be modified in a number of ways. Specific Card behavior can be established during the manufacturing process or at the time of Card issuance. Setting Card behavior upon activation, however, is ideal because it provides an adaptive, real time method that can be tailored to the specific needs of each retail environment and typical Cardholder behavior within those environments. This optimizes performance for Cardholders, Retailers, and Brands alike without requiring the Cardholder to carry multiple Cards.

To accomplish this, a portion of the data encoded into the activation signal contains configuration information that is decoded by the Card to set its behavior following activation. Card configuration settings can be established via software on a host PC and an Ethernet connection to the Activator. Wireless configuration through the Base Station is also possible so settings can be easily modified after installation without having to connect cables to the Activator.

A few examples of Card configuration parameters are listed below, but do not represent the entire range of possibilities—other parameters can be envisioned while remaining within the scope of the invention. The preferred embodiment allows predefined parameter sets to be selected from a limited list for data compactness. Other embodiments are envisioned that would allow adjustment of individual parameters with greater resolution, and remain within the scope of the invention. It is also envisioned that configurations could instruct Cards could to alter their behavior as a function of time or other parameters.

Examples of Card behavioral configuration parameters:

• • Beacon State time duration
    • Can range from a few seconds to two hours
    • Short duration useful in small stores with short Cardholder visits
    • Long duration useful in large stores with long Cardholder visits
  • Number of Card ID transmissions during Beacon State
    • Useful for very short Beacon duration
    • Useful in cases where repeated reading is undesired
  • Activation Holdoff time (default is zero)
    • Sets time after Beacon expiration during which Card activation is disabled
    • Reduces battery drain if a Card is accidentally left in the Store.
    • Minimizes unwanted re-activation when a departing Cardholder lingers in the entrance/egress area (i.e., within range of an Activator).
  • Activator ID (Card passes this value through to Readers as part of its ID)
    • Enables Store to know at which entrance a Card was activated.
    • Card behavior can be a function of the Activator ID

TABLE 2
ACTIVATOR ID BYTE USAGE
				Activ-
Activator		Beacon		ation
ID	Val-	Duration		Holdoff
(3 bits)	ues	(3 bits)	Value/Result	(2 bits)	Value/Result
0	0	0	1 Tx packet	0	~0
1	1	1	3 Tx packets	1	~30 seconds
2	2	2	~15 minutes	2	~60 seconds
3	3	3	~30 minutes	3	~300 seconds
4	4	4	~45 minutes
5	5	5	~60 minutes
6	6	6	~90 minutes
7	7	7	~120 minutes

Activation holdoff is defined as a period of time immediately following the expiration of the Beacon Mode, and during which the card cannot be activated.

Other behavioral options can be implemented in this way, but will require a larger Activator ID field or alteration of the above description (not described in this document). This basic capability provides a powerful yet flexible way to modify Card behavior, alter anticollision characteristics, etc. Care must be given, however, to maintain low power consumption.

Power Management

As previously stated, the Card has very little physical space for a battery. A special lithium metal thin-film battery with a storage capacity of 25 mA-Hr (milliampere-hours) is used in the present embodiment of the invention. The fully charged battery has a nominal terminal voltage of 3.0V, and the minimum operational threshold of the Card electronics is 2.2V. When the battery voltage drops below 2.2V, the Card will cease to function properly. This occurs at the end of t_LIFE as shown in FIG. 3. Power management techniques are used to maximize the functional life of the Card.

As shown in FIG. 3, the Card begins its life in the Bootstrap Mode 308, which is a process designed to ensure proper initialization. The Bootstrap Mode 308 has a fixed duration of t_MM, which is approximately 30 seconds in the present embodiment of the invention. The Card cannot be activated and has no external functionality during the Bootstrap Mode 308. Operations that occur in the Bootstrap Mode 308 are illustrated in FIG. 8. When the battery is connected 802, a power on reset (PoR) occurs 804, thus triggering the Bootstrap Mode 308. The Card then enters an extremely low power sleep state 806 for the fixed duration of t_MS, approximately 5.8 seconds. Reset pulse RB1 is automatically generated (t_MR) at the end of the sleep state 806, which retriggers the sleep state timer for another t_MS period. Reset pulse RB₂ occurs at the end of the second sleep period 806, causing another cycle to begin. This sleep/reset process repeats, storing the reset count in Card memory in each cycle. When five resets have accumulated in memory, Card firmware validates the process and exits the Bootstrap Mode 308. This ensures that intermittent battery connections during assembly do not cause improper Card initialization. The extremely low current and short duration of the Bootstrap Mode 308 results in negligible charge consumption from the battery.

The Card automatically enters the Transition Mode 310 when the Bootstrap Mode 308 completes successfully. Transition Mode 310 duration is defined by t_TM, which is approximately 12 hours in one embodiment. The Transition Mode 310 is a special low-power limited functionality mode designed to enable efficient Card testing during the remainder of the production process. The activity that occurs during the Transition Mode 310 is illustrated in FIG. 9. The sequence of events is similar to the Bootstrap Mode 308 except that the Card can be activated during the Listen period 904, t_TL, which is approximately 5.8 seconds in one embodiment. Like the Bootstrap Mode 308, a short reset pulse is generated at the end of the Listen period 904. When the reset count in memory equals the value preset in Card firmware (R_TF), the Card automatically exits the Transition Mode 310. In one embodiment, R_TF=7,448; yielding a t_TM of approximately 12 hours. If the Card receives an activation signal during a Listen frame 904, it will transmit one ID packet and then return to the Listen/Reset cycle. The Card will not respond to an activation signal that occurs during a reset pulse. The Transition Mode 904 allows Card functionality and ID transmission to be wirelessly tested. The Card spends the vast majority of the time in the low-power Listen state 904 while in the Transition Mode 310, and replies only when activation signals occur; minimizing energy usage. The Card consumes significantly more current during ID transmission, but this energy is quite low because of the short transmission time (˜14 ms, see FIG. 6). Because the Transition Mode lasts for a relatively short and fixed period of time, it consumes very little energy from the battery. The Card automatically enters the Normal Mode 312 at the end of the Transition Mode 310 and remains in the Normal Mode 310 until battery charge is depleted. Operation in the Normal Mode 310 has been previously described (refer for example to FIG. 3 and FIG. 4).

Energy Usage and Card Life

Battery capacity is specified in terms of current-time product, often expressed in units of milliampere-hours, or mA-Hr. For convenience reasons, this will be referred to as energy. The small thin-film battery used in the present embodiment of the invention has a capacity of only 25 mA-Hr. When the battery charge is depleted, the Card will cease to operate; making low power consumption a crucial factor in delivering a successful product to Cardholders and Advertisers.

Next, the energy consumed during each operating mode is described and calculated. This will show how the design of the Card/Activator/Reader System results in slow battery drain and long Card life.

Energy Consumed in the Bootstrap Mode

A current-time characteristic of the Bootstrap Mode 308 is illustrated in FIG. 10. The values of these parameters in one embodiment are:

• • I_MS=420 nA t_MS=5,800 sec
  • I_MR=1.2 mA t_MR=3.0 msec

The energy for each Sleep period is: I_MS*t_MS=2.436 μA-sec

The energy for each Reset pulse is: I_mR*T_MR=3.600 μA-sec

The energy in each Sleep/Reset cycle is the sum of these two figures and there are a total of five Sleep/Reset cycles, so total energy consumed in the Bootstrap Mode is:

E_BS=5(2.436 μA-sec+3.6 μA-sec)=30.18 μA-sec

Converting to units of mA-Hr: E_BS÷3,600 sec/Hr=8.38 nA-Hr total

Bootstrap Mode energy consumption is 0.000033% of the rated battery capacity (25 mA-Hr).

Energy Consumed in the Transition Mode

The current-time characteristic of the Bootstrap Mode is illustrated in FIG. 11.

The values of these parameters in one embodiment are:

I_TL=3.5 μA t_TL=5,800 sec

I_TR=1.2 mA t_TR=3.0 msec

The energy for each Sleep period is: I_TL*t_TL=20.30 μA-sec

The energy for each Reset pulse is: I_TR*T_TR=3.60 μA-sec

The energy in each Listen/Reset cycle is the sum of these two figures and there are a total of 7,448 Listen/Reset cycles, so total energy consumed in the Transition Mode is:

E_TM=7,448(20.3 μA-sec+3.6 μA-sec)=178 mA-sec

Converting to units of mA-Hr: E_TM÷3,600 sec/Hr=49.45 μA-Hr total

Bootstrap Mode energy consumption is 0.2% of the rated battery capacity (25 mA-Hr).

Energy Consumed in the Normal Mode

The current-time characteristic of the Normal Mode is illustrated in FIG. 12.

Sleep Mode duration is determined by the time between activations, while Beacon Mode duration is a parameter set by the Activator. Both values will vary greatly as a function of Cardholder shopping patterns and Store types, so typical values have been chosen for the purposes of energy calculations:

t_BM=1 hour (duration of each Beacon Mode cycle in the Card)

t_SM=1 week−t_BM=167 hours (time interval between Card activations)

Sleep Mode current and time parameters of one embodiment:

I_SD=420 nA (DC battery current consumed during the Deep Sleep state)

t_SD=182 ms (time duration of the Deep Sleep state within one Sleep Frame)

I_SL=3.5 μA (DC battery current consumed during the Listen state)

t_SL=45.5 ms (time duration of the Listen State within one Sleep Frame)

t_SF=227.5 ms (time duration of one Sleep Frame)

Beacon Mode current and time parameters of one embodiment:

I_BS=600 nA (battery current consumed during non-transmission periods [sleep])

t_BS=11.6 sec (fixed portion of the time interval between ID transmissions)

t_BD=variable (random Pre-Tx Delay, ranges from 10 to 1400 ms—use 1000 ms for calculations)

I_BT=9.00 mA (battery current consumed during the Transmit state)

t_BT=14 ms (time duration of a single ID packet transmission)

t_BF=variable (time duration of one Beacon Frame; varies per random delay time)

Sleep Mode Energy Calculation

The energy for each Deep Sleep period is: I_SD*t_SD=76.44 nA-sec

The energy for each Listen period is: ISL*TSL=159.25 nA-sec

The number of Sleep Frames in a typical Sleep Mode cycle (time between activations) is:

(167 hrs*(3,600 s/hr))÷t_SF=2.643×10⁶ Sleep Frames

The energy consumed in one Sleep Mode cycle is:

E_SM(cycle)=(2.643×10⁶)*(76.44 nA-sec+159.25 nA-sec)=622.93 mA-sec/week

Converting to units of mA-Hr: E_SM(cycle)÷3,600 sec/Hr=173 μA-Hr/week

Beacon Mode Energy Calculation

The energy for each Beacon Delay period is: I_BS*t_BD(avg)=600 nA-sec

The energy for each Beacon Sleep period is: I_BS*t_BS=6.96 μA-sec

The energy for each Beacon Transmit period is: I_BT*t_BT=126 gA-sec

The average delay period between transmissions is t_BS+t_BD(avg)=13.6 sec

The average Beacon Frame duration, t_BF(avg)=t_BSt_BD(avg)+t_BT=13.614 sec

The number of Beacon Frames in a typical Beacon Mode cycle is:

(1 hr*(3,600 s/hr))÷t_BF(avg)=273.5≈274 Beacon Frames

The energy consumed in one Beacon Mode cycle is:

E_BM(cycle)=(274)*(600 nA-sec+6.96 μA-sec+126 μA-sec)=36.60 mA-sec/week

Converting to units of mA-Hr: E_BM(cycle)÷3,600 sec/Hr=10.17 μA-Hr/week

Total Normal Mode Energy Calculation

The sum of typical Sleep Mode and Beacon Mode energy per cycle (one week) is:

E_SM(cycle)+E_BM(cycle)=173 μA-Hr+10.17 μA-Hr=183.17 μA-Hr/week

Weekly energy consumption in the Normal Mode is 0.73% of the rated battery capacity (25 mA-Hr).

Battery Life Calculation

Battery life is determined by the battery capacity divided by the energy used.

Parameter Summary:

• • Battery Capacity=25.00 mA-hr
  • E_MM=8.38 nA-H
  • E_TM=49.45 μA-Hr
  • E_SM(cycle)=173 μA-Hr/week
  • E_BM(cycle)=10.17 μA/week

$\begin{array}{c}\mathrm{Battery}\mathrm{life}=\left(\mathrm{Battery}\mathrm{Capacity}-E_{\mathrm{MM}}-E_{\mathrm{TM}}\right)÷\left(E_{\mathrm{SM}\left(\mathrm{cycle}\right)}+E_{\mathrm{BM}\left(\mathrm{cycle}\right)}\right)\\ =\left(25.00\mathrm{mA}-\mathrm{Hr}-8.38\mathrm{nA}-H-49.45\mu A-\mathrm{Hr}\right)÷\\ \left(173\mu A-\mathrm{Hr}\text{/}\mathrm{wk}+10.17\mu A-\mathrm{Hr}\text{/}\mathrm{wk}\right)\\ =136.215\mathrm{weeks}\\ =2.6195\mathrm{years}\\ \approx 2.62\mathrm{years}\end{array}$

The battery life consumed by the Bootstrap and Transition Modes combined is negligible (2 days):

Battery Life=Battery Capacity÷(E_SM(cycle)+E_BM(cycle)) ignores Bootstrap & Transition energy

=25.00 mA-Hr÷183.17 μA-Hr/week=136.485 weeks≡2.6247 years

So 2.6247 yrs−2.6195 yrs=0.0052 yrs≡1.9 days

For all intents and purposes, Card life is determined by Normal Mode energy consumption. For the preceding typical use case example, nearly 95% of battery energy is consumed in the Sleep sub-Mode. The Sleep Mode is also the natural mode of the Card, and is a good area of focus for energy reduction.

Card life could be extended, for example, by reducing the current consumed in the Listen state and/or the Deep Sleep state of the Sleep Mode. Since great effort has already been made to minimize these currents, this might be difficult to accomplish. Energy use can be reduced more easily, however, through Card firmware revisions (or option settings) that increase the Deep Sleep duration and/or reduce the Listen state duration. Increasing the Deep Sleep state duration from 182 ms to 227.5 ms (and therefore the Sleep Frame to 273 ms) would reduce Sleep Mode energy use from to 173 μA-Hr/week to 155.9 μA-Hr/week; increasing battery life from 2.6 to 2.9 years (about 3.5 months). Such changes, however, might adversely impact Card activation reliability because of the reduced opportunity to activate the Card (e.g., when the Card moves quickly through a small Activation Zone).

Reduced Beacon Mode duration will positively impact Card life, though not as strongly. In fact, many Cardholder Store visits may actually use much shorter Beacon Mode durations. Even if the Beacon Mode duration set by the Activator is typically only 15 minutes instead of one hour, Beacon Mode energy consumption would reduce from 10.17 μA-Hr/week to 2.54 μA-Hr/week; increasing Card Life from 2.62 years to 2.73 years (about 40 days). Decreasing transmit current will also have a positive impact on Card life, but may adversely impact read range; and must be considered carefully.

Other Considerations to Achieving Long Card Life

Other factors must be considered in the Card design to ensure that Card life is maximized. If, for example, Card transmit current consumption (I_BT) was higher than previously described, but lasted for a shorter duration to maintain equivalent energy usage; Card life may still be reduced. The battery has a finite source resistance, which gradually increases over time as the battery discharges and ages. The current consumed by the Card electronics flows through this internal source resistance, reducing the voltage available to actually power the Card electronics. When the instantaneous battery voltage available to Card electronics drops below the minimum operating threshold of the Card electronics, the Card will shut off, or truncate the operation it was going to perform. This is most likely to occur when the Card transitions from the low current Beacon Sleep state (I_BS) to the high current Beacon Transmit state (I_BT).

So, special effort is given to the Card design to minimize current consumption in all operational phases in the Card. Also, special care is given to battery specification and selection to achieve low internal source resistance and low source resistance degradation properties. Such design choices can reduce the strength of the signal transmitted by the Card, so special effort is also given to Reader design to maximize sensitivity to Card signals.

Batteries meeting these requirements are not commonly available. In addition to small area, extremely low thickness, desired terminal voltage, high storage capacity, low source resistance, and low degradation due to aging, the battery must also be capable of withstanding the pressures and temperatures of the hot lamination process without significant degradation in any of these critical properties. The design of the Card electronics, components & materials used, manufacturing processes, and Activator and Reader System design each play critical roles in the successful production of a high-performance and long-lasting product.

Various embodiments described above may be implemented using computer program modules, applications, or software for providing functionality described herein. In such implementations, computer program instructions and/or other logic are used to provide the specified functionality. Thus, a module or application can be implemented in hardware, firmware, and/or software. In one embodiment, program modules or applications formed of executable computer program instructions are stored in a non-transitory computer-readable storage medium, loaded into a memory, and executed by one or more processors to carry out the functions described herein.

The present invention has been described in particular detail with respect to a limited number of embodiments. Those of skill in the art will appreciate that the invention may additionally be practiced in other embodiments. The system may be implemented via a different combination of hardware and software from that described. Also, the particular division of functionality between the various system components described herein is merely exemplary, and not mandatory; functions performed by a single system component may instead be performed by multiple components, and functions performed by multiple components may instead be performed by a single component.

Finally, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter. Accordingly, the disclosure of the present invention is intended to be illustrative, but not limiting, of the scope of the invention.

Claims

1. A computer-implemented method for managing power in a dual frequency Active Radio Frequency Identification (RFID) transponder in a form factor substantially conforming to a credit card or smaller, the method comprising:

operating in a sleep mode, the sleep mode comprising a listen-only non-transmitting state of the transponder;

receiving, during the sleep mode, an activation signal from an activator at a distance of at least 10 feet from the transponder, the activation signal for activating the transponder from the sleep mode and controlling the transponder to operate in a beacon mode;

while operating in the beacon mode, transmitting an identifier signal identifying the transponder, the identifier signal detectable at a range of at least 20 feet from the transponder; and

responsive to ending operation in the beacon mode, re-entering the sleep mode.

2. The method of claim 1, wherein the transponder draws power from a thin film battery having a storage capacity of at least 25 mAH (milli-ampere-hours).

3. The method claim 1, wherein the transponder operates with a nominal terminal voltage of approximately 3 Volts.

4. The method of claim 1, wherein the transponder has a minimum operational threshold voltage of approximately 2.2 Volts.

5. The method of claim 1, further comprising:

controlling the transponder to operate in a bootstrap mode after an initial power-on of electronics of the transponder.

6. The method of claim 5, wherein transponder remains in the bootstrap mode for a fixed time duration.

7. The method of claim 5, wherein the transponder cannot be activated to enter the beacon mode while in the bootstrap mode.

8. The method of claim 5, further comprising:

detecting connection of battery terminals of the transponder to electronics of the transponder; and

entering the bootstrap mode responsive to the detection.

9. The method of claim 5, wherein controlling the transponder to operate in the bootstrap mode further comprises:

(a) entering a sleep state for a fixed time duration;

(b) generating a reset pulse after the fixed time duration of the sleep state;

(c) incrementing a reset count responsive to the reset pulse; and

(d) repeating steps (a)-(c) responsive to the reset count being less than a programmed count.

10. The method of claim 9, further comprising:

exiting the bootstrap mode when the reset count reaches the programmed count.

11. The method of claim 1, further comprising:

controlling the transponder to operate in a transition mode following completion of a bootstrap mode executed upon an initial power-on of the transponder, wherein at least one function of the transponder is limited in the transition mode.

12. The method of claim 11, wherein controlling the transponder to operate in the transition mode further comprises:

(a) entering a listen state for a fixed time duration;

(b) generating a reset pulse after the fixed time duration of the listen state;

(c) incrementing a reset count responsive to the reset pulse; and

(d) repeating steps (a)-(c) responsive to the reset count being less than a programmed count.

13. The method of claim 12, further comprising:

receiving the activation signal while the transponder is in the listen state; and

transmitting the identifier signal representing the identifier of the transponder responsive to the receiving the activation signal during the listen state.

14. The method of claim 1, further comprising:

controlling the transponder to operate in a normal mode following completion of a bootstrap mode and a transition mode, the bootstrap mode initiated upon an initial power-on of the transponder, and the transition mode initiated upon completion of the bootstrap mode, wherein operating in the normal mode comprises cycling between operating in the sleep mode and operating in the beacon mode.

15. The method of claim 14, wherein the transponder operates in the sleep mode for substantially more time than the transponder operates in the beacon mode over a lifetime of the transponder.

16. The method of claim 15, wherein operating in the sleep mode comprises:

consuming less than 173 micro-ampere-hour per week of operation in the sleep mode.

17. The method of claim 15, wherein operating in the sleep mode comprises:

cycling between a deep sleep state and a listen state, wherein the transponder can detect the activation signal in the listen state and does not detect the activation signal in the deep sleep state.

18. The method of claim 17, wherein the deep sleep state consumes 420 nano-amperes or less of current per cycle.

19. The method of claim 17, wherein cycling between the deep sleep state and the listen state comprises operating in the deep sleep state for 182 microseconds or less per cycle.

20. The method of claim 17, wherein cycling between the deep sleep state and the listen state comprises operating in the listen state for 46 microseconds or less per cycle.

21. The method of claim 17, wherein operating in the beacon mode comprises executing a series of beacon frames, wherein executing each beacon frame comprises:

operating in a beacon delay state for a delay duration randomly generated for each beacon delay state;

executing a beacon transmit comprising transmitting a packet representing the identifier of the transponder; and

operating in a beacon sleep period for a fixed duration.

22. The method of claim 21, wherein each beacon frame has a duration less than or equal to 13.614 seconds.

23. The method of claim 21, wherein the series of beacon frames during one cycle of the beacon mode comprises 274 or fewer frames.

24. The method of claim 1, wherein operating in the beacon mode comprises 10.17 micro-ampere-hours or less per week.

25. The method of claim 1, wherein further comprising consuming 183.17 micro-ampere-hours or less per week and achieving a battery life of at least two years.

26. A computer-readable storage medium storing computer-executable program instructions for execution by one or more processors, the instructions when executed causing the one or more processor to perform steps including:

controlling a transponder to operate in a sleep mode, the sleep mode comprising a listen-only non-transmitting state of the transponder;

receiving, during the sleep mode, an activation signal from an activator at a distance of at least 10 feet from the transponder, the activation signal for activating the transponder from the sleep mode and controlling the transponder to operate in a beacon mode;

while controlling the transponder to operate in the beacon mode, transmitting an identifier signal identifying the transponder, the identifier signal detectable at a range of at least 20 feet from the transponder; and

responsive to ending operation in the beacon mode, controlling the transponder to re-enter the sleep mode.

27. The computer-readable storage medium of claim 26, further comprising instructions for controlling the transponder to operate in a bootstrap mode following initial power-on of the transponder, the instructions for controlling the transponder to operate in the bootstrap mode including instructions for:

(a) entering a sleep state for a fixed time duration;

(b) generating a reset pulse after the fixed time duration of the sleep state;

(c) incrementing a reset count responsive to the reset pulse; and

(d) repeating steps (a)-(c) responsive to the reset count being less than a programmed count.

28. The computer-readable storage medium of claim 26, further comprising instructions for controlling the transponder to operate in a transition mode following completion of a bootstrap mode executed upon initial power-on of the transponder, the instructions for controlling the transponder to operate in the transition mode comprising instructions for:

(a) entering a listen state for a fixed time duration;

(b) generating a reset pulse after the fixed time duration of the listen state;

(c) incrementing a reset count responsive to the reset pulse; and

(d) repeating steps (a)-(c) responsive to the reset count being less than a programmed count.

29. The computer-readable storage medium of claim 26, further comprising instructions for controlling the transponder to operate in a normal mode following completion of a bootstrap mode executed upon initial power-on of the transponder and a transition mode executed upon completion of the normal mode, the instructions for controlling the transponder to operate in the normal mode comprising instructions for: cycling between operating in the sleep mode and operating in the beacon mode.

30. A dual frequency Active Radio Frequency Identification (RFID) transponder in a form factor substantially conforming to a credit card or smaller, the transponder including:

a processor; and

a computer-readable storage medium storing computer-executable program instructions for execution by the processor, the instructions for: operating in a sleep mode, the sleep mode comprising a listen-only non-transmitting state of the transponder; receiving, during the sleep mode, an activation signal from an activator at a distance of at least 10 feet from the transponder, the activation signal for activating the transponder from the sleep mode and controlling the transponder to operate in a beacon mode; while operating in the beacon mode, transmitting an identifier signal identifying the transponder, the identifier signal detectable at a range of at least 20 feet from the transponder; and responsive to ending operation in the beacon mode, re-entering the sleep mode.