# Patent

## Title
Time-domain reflectometry used to provide biometric authentication

## Abstract

An electronic device includes one or more Time-Domain Reflectometor (TDR) channels and a security block embedded at a silicon or software level to measure human electrical impedance and characteristics for biometric identification and provide biometric authentication.

## Background
Most multi-user operating systems include an authorization or access security process to protect computer resources by only allowing those resources to be used by consumers that have been granted authority to use them. When a consumer tries to use a resource, the authorization process checks that the consumer has been granted permission to use that resource. Resources may include individual files, data, computer programs, computer devices and functionality provided by computer applications. Permissions have generally been defined in some type of security policy application.
As technological developments permit compression of voice, video, imaging, and data information, the transfer of larger amounts of data have greatly increased the need to protect the integrity of the data and the data transfers by improving security measures in evolving applications. Therefore, improved circuits and methods for granting authorization and protecting data are needed.



BRIEF DESCRIPTION OF THE DRAWINGS
The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which:
FIG. 1 is a diagram that illustrates a portable device that is capable of executing an algorithm using time-domain reflectometry to provide biometric identification and authentication in accordance with the present invention;
FIG. 2 illustrates the use of time-domain reflectometry to provide characteristics for biometric identification;
FIG. 3 illustrates the outgoing step pulse and the returning echoes in the time-domain reflectometry used to provide biometric authentication; and
FIG. 4 illustrates a flow diagram that may be used to implement the algorithm using the time-domain reflectometry for biometric authentication.



It will be appreciated that for simplicity and clarity of illustration, elements illustrated in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals have been repeated among the figures to indicate corresponding or analogous elements.
DETAILED DESCRIPTION
In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present invention.
The embodiment illustrated in FIG. 1 shows a wireless communications device 10 that includes one or more radios to allow communication with other over-the-air communication devices. Communications device 10 may operate as a cellular device or a device that operates in wireless networks such as, for example, Wireless Fidelity (Wi-Fi) that provides the underlying technology of Wireless Local Area Network (WLAN) based on the IEEE 802.11 specifications, WiMax and Mobile WiMax based on IEEE 802.16-2005, Wideband Code Division Multiple Access (WCDMA), and Global System for Mobile Communications (GSM) networks, although the present invention is not limited to operate in only these networks. The radio subsystems collocated in the same platform of communications device 10 provide the capability of communicating in an RF/location space with other devices in a network.
It should be noted that the present invention is not limited to wireless applications and may be used in a variety of products. For instance, the claimed subject matter may be incorporated into desktop computers, laptops, MP3 players, cameras, communicators and Personal Digital Assistants (PDAs), medical or biotech equipment, automotive safety and protective equipment, automotive infotainment products, etc. However, it should be understood that the scope of the present invention is not limited to these examples.
The simplistic embodiment illustrates the coupling of antenna(s) to the transceiver 12 to accommodate modulation/demodulation. In general, analog front end transceiver 12 may be a standalone Radio Frequency (RF) discrete or integrated analog circuit, or transceiver 12 may be embedded with a processor as a mixed-mode integrated circuit where the processor processes functions that fetch instructions, generate decodes, find operands, and perform appropriate actions, then stores results. The processor may include baseband and applications processing functions and utilize one or more processor cores 20 and 22 to handle application functions and allow processing workloads to be shared across the cores. The processor may transfer data through an interface 26 to memory storage in a system memory 28.
Traditionally Time-Domain Reflectometry (TDR) techniques have been employed in a variety of applications that include determining the characteristics of electrical lines; measuring the moisture of unsaturated soils; detecting fluids for leak and pollution discovery; measuring water pressures and water levels for hydrological purposes; monitoring deformation and stability of mine slopes and structures, among other applications. However, in accordance with the present invention TDR techniques have been employed and shown in the embodiment for communications device 10 to facilitate biometric measurements that are pertinent to applications having identity authentication systems. Specifically, time-domain reflectometry & security block 14 enables measurements to generate an impedance profile of selected objects.
Time-domain reflectometry consists of feeding an impulse of current or voltage into TDR channels 16 and then observing that reflected energy by reflectometry & security block 14. This may be done in parallel for the individual channels or it may be done synchronously. TDR channels 16 include multiple conductors to supply a fast-rise pulse and receive the resultant reflections from selected target locations. By analyzing the magnitude, deviation, and shape of the reflected waveform the electrical differences, the discontinuities and the waveform variations provide a pattern to uniquely identify the target object. Specifically, TDR & security block 14 enables a short pulse of energy and analyzes the echo return to reveal details of the reflecting object which are captured to generate impedance mismatches and an impedance profile.
FIG. 2 illustrates that in this example embodiment time-domain reflectometry provides a direct look at hand characteristics. TDR & security block 14 enables the pulse and characterizes the reflected voltage waves to reveal the characteristic impedance of desired locations on the hand as indicated by TDR contact 202, TDR contact 204, TDR contact 206, TDR contact 208 and TDR contact 210. Although FIG. 2 shows a hand to illustrate the use of finger print scanners, other types of example applications may include thermal hand imagers, retinal scanners and facial recognition systems. The processor may execute the proper software to perform, for example, an Inverse Fast Fourier Transform (IFFT) in generating a digital representation of the reflected pulse from the incident pulse. The processor compares the digitized reflected waveform to a database that may be stored in system memory 28, or alternatively, a database accessible to communications device 10 through external communications. Various waveform correlation algorithms may be employed to determine whether or not a given measurement matches a waveform in the authentication database, and if so, to what degree of confidence. This allows for varying degrees of authentication quality and may also prompt the system user for additional modes of authentication.
Note that in some embodiments the comparison of the digitized reflected waveform to the stored database may be performed by the processor, or alternatively, by an external server with access to the stored database. Once the processor of communications device 10 or the external server determines a match, authentication is indicated and the user may be granted additional permission rights. Thus, the TDR techniques provide a digitized reflected waveform biometrics characterization that may be compared with records in a stored database and the comparison results may be applied to personal security and authentication.
In an alternate embodiment, Optical Time Domain Reflectometor techniques may be used to provide a short intense laser pulse and the reflected light analyzed for light loss, degree of backscatter and reflection of light. The TDR analysis begins with the propagation of a step or impulse of energy and the subsequent observation of the energy reflected by the system to determine the reflected light characteristics analyzed to establish the hand characteristics. By analyzing characteristics such as, for example, magnitude, duration and shape of the reflected waveform, the nature of the impedance variation in the reflected light may be determined. This technique may be applied to one of the hands, eyes, to a portion of skin or other biometric target. The illuminating laser would be relatively low amplitude for safety but still provide an amplitude sufficient for modern optical and OTDR receivers to discern.
FIG. 3 illustrates the waveform of the outgoing step pulse and the returning echoes for a TDR system. An examination of the time delay and wave shape of the echoes present allows a record of discontinuities and characteristics of the hand. In this embodiment five TDR channels are illustrated by the five TDR contacts used to uniquely characterize individual patterns for the hand of a person. The characteristics of the electrical path are very different from finger to finger and from person to person. The characteristic waveforms from different TDR channels may be compared with a database of stored waveforms in a database to determine authentication.
FIG. 4 is a flowchart that in accordance with various embodiments of the present invention illustrates an algorithm that uses a TDR method of identifying characteristic waveforms to provide security in various operations. Thus, method 400 may be used in a computer system that supports a single processing engine, or a system having multiple processing cores or multiple security domains to protect secrets that applications are allowed to use. Method 400 determines an authorization to permit an association between the processing cores or security domains and a designated set of secrets for all commands sent to the processing device.
In some embodiments, method 400, or portions thereof, is performed by a controller, a processor, or an electronic system, embodiments of which are shown in the various figures. Method 400 is not limited by the particular type of apparatus, software element, or system performing the method. The various actions in method 400 may be performed in the order presented, or may be performed in a different order. Further, in some embodiments, some actions listed may be omitted from method 400.
Method 400 is shown beginning at block 402 in which a pulse is sent out using TDR techniques by communication device 10. Block 404 shows that the TDR digitizes reflections from the incident pulse. Block 406 shows that the host processor compares the digitized reflected waveform to a database. Block 408 shows that the host processor determines authentication based on the comparison of the digitized reflected waveform to the stored database.
By now it should be apparent that embodiments of the present invention allow high-performance biometric authentication that may be used in applications such as, for example, finger print scanners, thermal hand imagers, retinal scanners and facial recognition, among others. By using a TDR & security block embedded at a silicon level, TDR techniques may be integrated into a trusted platform module that may be used in a variety of platforms in mobile devices to provide scanner or imaging methods for biometric authentication. Without requiring an imager, a clean sensor, or any other proprietary hardware, the TDR & security block may be instantiated in a variety of form factors including mobile phones, handheld PDA's, laptops, keyboards, mice, etc. Thus, in accordance with the present invention TDR data may be taken to measure human impedance and characteristics for biometric identification.
While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

## Claims

1. A device comprising:
a time-domain reflectometry (TDR) and security block within a processor, the TDR and security block arranged to execute TDR techniques to obtain a digitized reflected waveform to measure human impedance and characteristics for biometric identification, analyze one or more of a magnitude and a shape of the digitized reflected waveform, and match the digitized reflected waveform to a record in an authentication database to provide biometric authentication, wherein the record uniquely identifies a person.

2. The device of claim 1 wherein the TDR and security block is embedded at a silicon level of the device, wherein the device is a portable device.

3. The device of claim 1 wherein the TDR and security block conducts a short pulse of energy and analyzes an echo return to reveal details of a reflecting object.

4. The device of claim 3 wherein the TDR and security block analyzes the echo return to generate impedance mismatches and an impedance profile.

5. A communications device comprising:
a memory storage; and
a processor to execute time-domain reflectometry (TDR) techniques arranged to obtain a digitized reflected waveform, generate a biometrics characterization by analyzing one or more of a magnitude and a shape of the digitized reflected waveform, and compare the digitized reflected waveform with records in the memory storage to determine biometric identification used for personal security by the communications device, wherein each of the records uniquely identifies a person.

6. The communications device of claim 5 wherein the process further executes TDR techniques to conduct a short pulse of energy to an object and analyzes a reflected waveform to reveal details of the object.

7. The communications device of claim 6 wherein the memory storage is to store an impedance profile for the reflected waveform from the object.

8. The communications device of claim 7 wherein the impedance profile is compared to a stored database to determine a match condition that determines the biometric identification.

9. A method executed by a device having memory storage and a processor comprising:
executing time-domain reflectometry (TDR) by conducting a short pulse of energy from the processor from a TDR interface;
analyzing an echo returned to the TDR interface to reveal details of a reflecting object, wherein analyzing the echo comprises analyzing one or more of a magnitude and a shape of a digitized reflected waveform; and
comparing records in an authentication database in the memory storage with a digitized characterization of the details of the reflecting object to determine a match condition, wherein each of the records uniquely identifies a person.

10. The method of claim 9 further including:
using the match condition for personal security by the device to provide biometric authentication.

11. The method of claim 10 further including:
using the TDR interface in the processor to provide multiple TDR channels that conduct the short pulse and receive the echo that is used in determining the biometric authentication.

12. The method of claim 9 further including:
using the multiple TDR channels to generate a biometrics characterization from scanning finger prints.

13. The method of claim 9 further including:
using the multiple TDR channels to generate a biometrics characterization from thermal hand images.

14. The method of claim 9 further including:
using the multiple TDR channels to generate a biometrics characterization from retinal scans.

15. The method of claim 9 further including:
using the multiple TDR channels to generate a biometrics characterization from facial scans.