Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/255,813, filed Dec. 15, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to networked electronic systems, and more particularly to a system and method for determining whether components of a wireless networked system are co-located within a common room or area. 
     2. Description of the Background Art 
     Increasingly, electronic communication systems such as audio or video conferencing systems are utilizing wireless networks to link system components such as microphones, speakers, and the like. Wireless networks offer the substantial benefit of eliminating cables and associated connectors and allow component devices to be easily and freely positioned relative to each other. Additionally, wireless networks allow system components to be easily rearranged to suit the needs of the user. 
     A disadvantage associated with wireless communication systems is the potential for unintended dissemination of confidential or sensitive information. In a conference setting, it is desirable to limit access to the conference information only to conference participants. To facilitate this need, conference systems are typically located in a fully enclosed space such as a conference room. However, most commercially available wireless networked communication systems employ radio frequency (RF) signals to transmit data between and among the various system components. These RF signals may easily penetrate walls, ceilings, and other room barriers, and thus be inadvertently transmitted to components outside of the present communication system (e.g., a component of another wireless system located in a second conference room). Data transmission of RF signals outside of the immediate conference room may result in an unintentional and undesirable disclosure of proprietary or sensitive information, and also allows interception by eavesdroppers or industrial spies, thereby compromising confidentiality. 
     One method of preventing the inadvertent dissemination of confidential information is to encrypt transmissions between the system components. Alternatively, the carrier frequencies used for transmitting conference data may be varied. However, such solutions are generally difficult to implement, expensive, and/or may require user intervention. 
     Accordingly, there is a need for a system and method for determining whether wireless networked components are co-located within a common room or area. There is a more specific need for a system and method for discriminating between co-located conference components and external (out-of-room) components, which does not require operator intervention. 
     SUMMARY 
     The present invention provides a system and method for determining whether wireless networked devices are co-located within a conference or other room, and discriminating against those which are not co-located. In one embodiment, components of a wireless conferencing system are each provided with an acoustic sensor or similar instrument for detecting ambient or specially generated acoustic signals, and responsively generating signals representative of the detected sounds. These representative signals concurrently generated by each of the conferencing system components are transmitted via radio frequency to a signal analysis processor (SAP), which compares the signals to a reference signal (which is typically a signal generated by a component known to be located within the conference room) for co-location. The SAP may be embodied in any of the system components or in a separate device designated for the discrimination analysis. The SAP may utilize any one of a number of well-known signal comparison techniques, including correlated envelope energy analysis, harmonic frequency energy comparison, and cross-correlation analysis. 
     Since sound is attenuated by walls and other barriers, representative signals generated by components located outside of the conference room will not match the reference signal. Upon a determination that the representative signal received from a system component does not match the reference signal and thus is not co-located, a base station of the conferencing system (which manages communications to and from the various components) discriminates against the non co-located component to prevent subsequent date transmissions to or from the non co-located component. 
     Alternative embodiments of the invention may employ comparative analysis of other types of ambient or specially generated energy detected at each of the conference system components, wherein the ambient or specially generated energy is of a form (e.g., infrared energy) which does not readily penetrate conference room walls or similar barriers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view of an exemplary environment where embodiments of the present invention may be implemented; 
         FIG. 2  is a block diagram of an exemplary base station and remote device of the present invention; 
         FIG. 3  is a block diagram of an exemplary alternative base station and remote device of the present invention; 
         FIG. 4  is a diagram of signal waveform comparisons; 
         FIG. 5  is a flowchart showing the steps of a method for co-location discrimination analysis, according to the present invention; and 
         FIG. 6  is a flowchart of an alternative method for co-location discrimination analysis, according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  depicts components of an exemplary wireless communication system  100  for conducting meetings between persons or groups of persons located remotely from each other. The communication system  100  may comprise, but is not limited to, a video conferencing or audio conferencing system of the type sold by Polycom, Inc. of Milpitas, Calif. The communication system  100  includes a base station  102  having primary system circuitry configured to receive and process conference data. Additionally, base station  102  may be configured to manage communications with other conferencing systems (e.g., video conferencing systems located at other sites) over conventional circuit or packet switched networks, such as a public switched telephone network or the Internet. 
     The communication system  100  also includes a plurality of remote devices  104 ,  106 , which communicate with the base station  102  and each other through electromagnetic signals, typically radio frequency (RF) signals. Alternatively, infrared signals or other suitable electromagnetic signals may be employed for communication between various communication components. Remote devices  104 ,  106  may include wireless microphones, wireless speakers, or other devices coupled wirelessly such as personal computers, LCD projectors, video monitors, and other conference-related items. It is noted that while two remote devices  104 ,  106  are depicted in  FIG. 1 , a lesser or greater number of remote devices may be utilized. 
     The components of the communication system  100  are located within a first conference room  110 . Those skilled in the art will appreciate that even low power RF signals will easily penetrate walls and similar physical barriers, such as a wall  112  separating an adjacent second conference room  114  from the first conference room  110 . Occasionally, RF signals generated by the base station  102  located in the first conference room  110  may be communicated to a remote device  116 , which is not part of communication system  100 , located in the second conference room  114 . The information underlying the transmitted RF signals may be inadvertently disseminated to persons having access to the remote device  116 . If this information is sensitive, the confidentiality of the information is then compromised. Further, RF signals generated by the remote device  116  may inadvertently be transmitted and subsequently processed by the base station  102 . 
     The present system and method will secure against inadvertent disclosure of confidential information. Inadvertent disclosure is prevented by determining which remote devices are co-located in the same communication system  100  as the base station  102 , and thus only allow co-located devices to exchange conference data with each other and the base station  102 . The term “conference data”, as used herein, denotes data representative of any information which may be presented to users of the communication system  100  during the operating thereof, including speech, images, and the like. As previously mentioned, the conference data is typically exchanged between components of the communication system  100  through the use of RF signals. 
     For co-location discrimination analysis, an acoustic signal is sampled by all communication components (i.e.,  102 ,  104 , and  106 ). This acoustic signal is separate and distinct from the radio frequency (RF) signals typically used for data exchange, and is not in the same frequency band as the RF signals. Thus, the acoustic signal may include ultrasonic and subsonic audio sources. Furthermore, the acoustic signal may be environmental (i.e. speech within the room) or specifically generated for co-location discrimination analysis. Although the present embodiment is described as using acoustic signals, those skilled in the art will recognize that alternative energy signals or light signals, such as infrared signals pulsing through light emitting diodes (LED) may be utilized for the discrimination analysis. 
     Because the acoustic signal is attenuated outside of the first room  110 , the remote device  116  located in the second room  114  will sample a weaker or dissimilar acoustic signal as compared to the remote devices  104 ,  106  located in the first room  110 . Thus, a comparison of the sample taken by the remote device  116  will be different from the samples taken by the base station  102  and the remote devices  104 ,  106 , thereby resulting in a determination by a signal analysis processor (not shown) within the communication system  100  that the remote device  116  is not co-located in the first room  110 . 
     Furthermore, the co-location discrimination analysis can be continuous or pulsed. Continuous discrimination analysis will occur at low levels so as not to disturb occupants of the first room  110 . Alternatively, analysis may be conducted periodically. For example, the discrimination analysis may shut down for a period of time before subsequently activating to sample, process, and analyze acoustics signals before shutting down again. 
     Additionally, the length of time for acoustic signal sampling is dependent upon the desired accuracy of the discrimination analysis. For higher accuracy, the sampling must be of a longer duration while a lower accuracy will allow for a relatively shorter sampling of the acoustic signal. 
     Referring to  FIG. 2 , discrimination analysis components of a base station  102  and an exemplary remote device  104  are depicted. In one embodiment, base station  102  performs the co-location discrimination analysis, and is preferably provided with an acoustic sensor  202 , a signal processor  204 , a signal analysis processor (SAP)  206 , an RF transceiver  208 , and a memory  210  all coupled to a common system bus  212 . The acoustic sensor  202  samples an external acoustic signal and forwards the sample to the signal processor  204  for processing. The signal processor  204  converts the sample into a digital signal that is representative of the sampled acoustic signal. This digital signal is sent to an SAP  206  and subsequently becomes the reference signal for discrimination analysis. 
     The sampled acoustic signal may be ambient or specifically generated for discrimination analysis. For example, a signal generator may be contained within the base station  102  or the remote devices  104 ,  106  (FIG.  1 ). This signal generator may be embodied as a speaker emitting sound waves, or alternatively, a light-emitting diode (LED) device for emitting infrared or other light. Those skilled in the art will recognize that other forms of detectable energy signals may be generated and utilized for discrimination analysis. 
     As shown further in  FIG. 2 , the remote device  104  is provided with an acoustic sensor  214 , a signal processor  216 , and an RF transceiver  218 . Each component of the remote device  104  is directly coupled to a common system bus  220 . 
     The acoustic sensor  214  samples the same external acoustic signal as that sampled by the base station  102 , and forwards the sample to the signal processor  216 . The signal processor  216  subsequently converts the sample into a digital signal that is representative of the sampled acoustic signal. The RF transceiver  218  then sends this representative signal to the RF transceiver  208  of the base station  102 . Thus, these RF transceivers  208 ,  218  may be utilized for both data conference transmissions and discrimination analysis transmissions. The RF transceiver  208  forwards the representative signal received from the remote device  104  to the SAP  206  for discrimination analysis. The SAP  206  compares the reference and representative signals to determine whether the signals are equivalent or within a predetermined threshold. If the SAP  206  determines signal equivalence, the remote device  104  is co-located within the same wireless communication system as the base station  102 . 
     The memory  210  may embody a list of remote devices in communication with the base station  102 . This list is periodically updated when a remote device is determined to be external to or non co-located with the communication system of the base station  102 . If the SAP  206  determines that a remote device and the base station  102  are not within the same communication system, the base station  102  discriminates against the non co-located device by removing the remote device from the list in memory  210 . Consequently, all communications with the non co-located device are discontinued, information received from this non co-located device is not processed, and the base station  102  may transmit a shutdown signal to the non co-located device. 
     Thus, the embodiment shown in  FIG. 2  illustrates discrimination analysis being performed by the base station  102 . The remote devices forward their representative signals to the base station for comparison with the reference signal. If the reference and representative signals are comparable, then the SAP  206  concludes that the remote device is co-located within the same communication system as the base station  102 . However, if the remote device is not co-located, the base station  102  discriminates against the remote device by disregarding all communications with the remote device. Additionally, the base station  102  may send a shutdown signal to the non co-located remote device. 
     In another embodiment of the communication system, each remote device conducts the co-location discrimination analysis.  FIG. 3  shows a block diagram of discrimination analysis components of a base station  300  and an exemplary remote device  310  for the alternative embodiment. The base station  300  includes an acoustic sensor  302 , a signal processor  304 , and an RF transceiver  306  all coupled to a common system bus  308 . 
     As previously discussed in connection with the acoustic sensor  202 , the acoustic sensor  302  samples an external acoustic signal and forwards the sample to the signal processor  304 , which converts the sample into a digital signal representative of the sampled acoustic signal. Subsequently, this representative signal is forwarded via the system bus  308  to the RF transceiver  306 , where the representative signal is transmitted to each remote device  310 . In this embodiment, the digital signal from the base station  300  is the representative signal used for discrimination analysis. 
       FIG. 3  also depicts components of an exemplary remote device  310 , which includes an acoustic sensor  312 , a signal processor  314 , an RF transceiver  316 , and a signal analysis processor (SAP)  318 . At relatively the same instance the base station  300  samples an external acoustic signal; each remote device  310  also samples the same acoustic signal with the acoustic sensor  312 . The signal processor  314  subsequently converts the sample into a digital signal that is representative of the sampled acoustic signal. This digital signal is subsequently forwarded via a system bus  320  to the SAP  318  for discrimination analysis. Because each remote device  310  performs the discrimination analysis, the digital signal generated by the signal processor  314  is the reference signal. If the SAP  318  determines that the reference and representative signals are not similar, then the remote device  310  is not co-located within the same communication system as the base station  300 . Consequently, the remote device  310  stops communicating with the wireless communication system of the base station  300 , and may subsequently shut itself down. 
       FIG. 4  is a diagram comparing signal waveforms of reference and representative signals. For simplicity of illustration,  FIG. 4  will be discussed in connection with the communication system utilizing the embodiment of FIG.  1  and FIG.  2 . As shown, the base station  102  ( FIG. 1 ) produces a reference signal  402  that is representative of a sampled acoustic signal. At relatively the same instance, the remote devices  104 ,  106 , and  116  also sample and process the same acoustic signal. This results in the remote devices  104 ,  106 , and  116  producing representative signals  404 ,  406 , and  408 , respectively. 
     There are many well-known methods for comparing acoustic signals, which may be implemented for co-location discrimination analysis. One such method is correlated envelope energy analysis. In this method, the SAP  206  ( FIG. 2 ) determines if an envelope of each of the representative signals  404 ,  406 , and  408  is similar in form to an envelope of the reference signal  402 . Thus, the similarity in amplitude of the waves is less important than whether the representative signals  404 ,  406 , and  408  have generally similarly occurring valleys and peaks. 
     An alternative method involves a comparison of (harmonic) frequency energy. In this method, for example, the SAP  206  determines if a high pitch sound received at the base station  102  is also perceived at each remote device  104 ,  106 ,  116 . Thus, this method searches for correlation between the sinusoidal components of representative signals  404 ,  406 , and  408  with the sinusoidal components of reference signal  402 . 
     Additionally, cross-correlation analysis of the local and remote representative signals may determine if the devices sampled the same acoustic signal. This method generally compares the peaks of the representative signals  404 ,  406 , and  408  with the reference signal  402  to determine if similar peaks exist. Those skilled in the art will recognize that many other methods of signal analysis may be utilized for co-location discrimination. 
     Since the remote devices  104 ,  106  are located within the first room  110  ( FIG. 1 ) with the base station  102 , remote representative signals  404  and  406  are very similar to the reference signal  402  of the base station  102 . Therefore, the SAP  206  analysis concludes that the remote devices  104 ,  106  are co-located within the same communication system as the base station  102 , and will continue to communicate with the remote devices  104 ,  106 . 
     The remote device  116  is not located within the communication system  100  ( FIG. 1 ) of the first room  110 . Since the acoustic signal distorts while traveling through the wall  112  (FIG.  1 ), the representative signal  408  is dissimilar to the reference signal  402  of the base station  102 . Therefore, the SAP  206  analysis will conclude that the remote device  116  and the base station  102  are not co-located. Discrimination against the remote device  116  will thus occur wherein communications between the remote device  116  and the base station  102  are disregarded, and remote the device  116  may shut down. 
       FIG. 5  is a flowchart  500  that illustrates a method for co-location discrimination analysis with the analysis being performed at the base station  102  (FIG.  2 ). Initially in step  502 , a remote device  104  ( FIG. 2 ) and the base station  102  sample an acoustic signal with their respective acoustic sensors  214 ,  202  (FIG.  2 ). This acoustic signal may be from an external environmental source or be generated by a remote device  104  or by the base station  102 . Alternatively, other forms of energy signals may be utilized for the analysis such as a light signal emitted from a light-emitting diode (LED) device. The samples are then processed into digital signals that are representative of the acoustic signal. Since the base station  102  performs the discrimination analysis, the representative signal generated by the base station  102  is the reference signal. 
     In step  504 , the remote device  104  transmits its representative signal of the acoustic signal sample to the base station  102  for co-location discrimination analysis. The representative signal is received by an RF transceiver  208  ( FIG. 2 ) in the base station  102 , and is subsequently forwarded to an SAP  206  (FIG.  2 ). In step  506 , the SAP  206  compares the representative signal with the reference signal generated by the base station  102 . Those skilled in the art will recognize that there are numerous ways to conduct this analysis. Some of these methods include correlated envelope energy analysis, (harmonic) frequency energy comparison, and straight correlation analysis. 
     If in step  506  the analysis shows that the representative signal is not similar to the reference signal, then in step  508 , the base station  102  removes the remote device  104  from a communication list stored in memory  210  ( FIG. 2 ) and stops processing conference data from/for this particular remote device  104 . Additionally, a signal may be sent to the non co-located remote device to shut down. Alternatively, if the reference and representative signals are comparable, then the base station maintains communications with the remote device in step  510 . 
     Should co-location discrimination analysis continue either periodically or continuously, then in step  512  a subsequent acoustic signal will be perceived, and the discrimination analysis will proceed through another cycle. Alternatively, if the conference concludes, then there will not be a subsequent acoustic signal and the co-location discrimination analysis ends. 
       FIG. 6  is a flowchart  600  illustrating another method for co-location discrimination analysis wherein each remote device performs the co-location discrimination analysis. Initially in step  602 , a remote device  310  ( FIG. 3 ) and a base station  300  ( FIG. 3 ) sample an acoustic signal, and process the samples into digital signals that are representative of the acoustic signal. Since the remote device  310  performs the discrimination analysis, the digital signal of the remote device  310  is the reference signal. 
     In step  604 , the base station  300  transmits its representative signal to each remote device  310 . Each remote device  310 , upon receipt of the representative signal, forwards the representative signal to an SAP  318  (FIG.  3 ). 
     In step  606 , the SAP  318  compares the representative signal to the reference signal generated by each remote device  310 . The discrimination analysis may include such methods as correlated envelope energy, (harmonic) frequency energy, and straight correlation analysis. If in step  606  the analysis shows the reference and representative signals are dissimilar, then in step  608 , the remote device  310  stops communicating with the base station  300 . Furthermore, the remote device  310  may shut itself down. Alternatively, if the reference and representative signals are comparable, then the remote device  310  maintains communications with the base station  300  in step  610 . 
     Should the conference continue, then in step  612 , a subsequent acoustic signal is generated and the discrimination analysis will proceed through another cycle. 
     The invention has been explained above with reference to particular embodiments. Other embodiments will be apparent to those skilled in the art in light of this disclosure. For example, a separate, dedicated device may contain an SAP for performing the co-location discrimination analysis. Alternatively, reference signals may be generated by a third device known to be within the communication system. Any device that contains an SAP can then utilize this reference signal. Therefore, these and other variations upon the specific embodiments are intended to be covered by the present invention, which is limited only by the appended claims.

Technology Category: h