Abstract:
A teacher microphone ( 30 ) is provided with an infrared (IR) transmitter to signal a connection request to a wireless audio access point ( 50 ) using a first IR request inquiry signal ( 331 ). In response to this first IR code, the wireless audio access point establishes a first RF communication link ( 300 ). After the first RF communication link is established, the teacher microphone conditionally transmits a first IR presence signal ( 332 ) to verify that it is still collocated in the local vicinity of the wireless audio access point, such as being in the same room. The wireless audio access point is capable of maintaining a connection with additional portable wireless devices, such as a student microphone ( 40 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of pending application U.S. Ser. No. 12/466,854, filed on May 15, 2009, and which is hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    The present invention relates to networks of devices that can be connected using wireless links. Specifically, embodiments of the present invention pertain to a method and system for selecting and connecting to wireless access point within a local area network. 
         [0004]    2. Background Art 
         [0005]    Prior art  FIG. 1  depicts a wireless radio frequency (RF) microphone  10  that is sending audio, via a Bluetooth® RF communication link  100 , to a wireless audio access point  15 . Bluetooth is a trademark of Bluetooth SIG, Inc. This application is suitable for a teacher, using this wireless RF microphone  10 , to address students in a classroom setting. Audio distribution using wireless RF communication is well understood in the prior art. Similar transmission methods using alternative RF communication protocols are also well understood in the art. For example, Wi-Fi® devices communicate using the IEEE 802.11 standards. Wi-Fi is a trademark of the Wi-Fi Alliance. It is also well known in the prior art to use IEEE 802.11 in conjunction with Internet Protocol to wirelessly transmit audio data, such as in Voice over Internet Protocol (VoIP) applications. 
         [0006]    One recent advance in wireless RF communication is Wi-Fi Direct, a wireless standard that allows Wi-Fi devices to communicate directly with each other without the need for a router. This peer-to-peer communication standard can be implemented in any Wi-Fi device. Those skilled in the art will recognize the advantages of transmitting audio data directly from a wireless microphone to a wireless audio access point in accordance with the Wi-Fi Direct specification. 
         [0007]    Wireless RF communication can be established by a device, such as a microphone  10 , by first broadcasting an inquiry message  101  to a wireless audio access point, such as an audio distribution point  15 , which responds by broadcasting an inquiry response message  102 . 
         [0008]      FIG. 2  depicts a portion of a school building having several classrooms with the range of a typical wireless device thereupon superimposed. This clearly shows that in a school setting, the range  210  of a typical wireless device, such as wireless audio access point  15 , located in a first classroom  21  extends well beyond the confines of that classroom. As shown, the wireless audio access point  15  located in the first classroom  21  would try to establish RF communication  100 , with any compatible wireless devices located in a second classroom  22 , a fourth classroom  24 , and a fifth classroom  25 . The wireless audio access point  15  also potentially interacts with some portion of the devices in a third classroom  23 , a sixth classroom  26 , a seventh classroom  27 , and an eighth classroom  28 . In fact, in the typical school layout illustrated only devices in a ninth classroom  29  would not interact with the wireless audio access point  15  in the first classroom  21 . 
         [0009]    The prior art does not provide an effective means of limiting wireless communications to the confines of a single classroom. The problems associated with employing a wireless microphone device in a multiple classroom setting are compounded when multiple wireless microphones are employed. For example, envision a classroom setting with both a teacher microphone and multiple student microphones. The solution to the original problem must now take into account the additional issues of interference, coordination and interoperability. 
       SUMMARY OF THE INVENTION 
       [0010]    It is to be understood that both the general and detailed descriptions that follow are exemplary and explanatory only and are not restrictive of the invention. 
       DISCLOSURE OF INVENTION 
       [0011]    Accordingly, a need exists for a classroom audio system that allows teachers and students to move between several classrooms with each teacher and student retaining use of his own personal wireless microphone. The embodiments of the present invention provide these advantages and others not specifically mentioned above but described in the sections to follow. 
         [0012]    According to a first aspect, the present invention provides a wireless communication system comprising two portable wireless devices and a wireless communication access point. The first portable wireless device comprises a radio frequency (RF) digital transceiver and a first infrared (IR) transmitter adapted to transmit a first IR request inquiry signal and a first IR presence signal. The second portable wireless device comprises a RF digital transceiver and a second IR transmitter adapted to transmit a second IR request inquiry signal and a second IR presence signal. The wireless communication access point comprises two RF digital transceivers, each digital transceiver communicating with a corresponding portable wireless device, and an IR sensor that receives the first and second IR request inquiry signals and the first and second IR presence signals from the wireless devices. 
         [0013]    According to a second aspect, the present invention provides a wireless audio distribution system suitable for use in a classroom setting. The audio distribution system comprises a teacher microphone, a student microphone, and a wireless audio access point. The teacher microphone comprises a RF digital transceiver, a first IR transmitter adapted to transmit a first IR request inquiry signal and a first IR presence signal, and a microphone element. The student microphone comprises a RF digital transceiver, a second IR transmitter adapted to transmit a second IR request inquiry signal and a second IR presence signal, and a microphone element. The wireless audio access point comprises two RF digital transceivers and an IR sensor adapted to receive the first and second IR request inquiry signals and the first and second IR presence signals. The teacher microphone and the wireless audio access point establish wireless RF communication upon detection of the first IR request inquiry signal at the wireless audio access point. The wireless audio access point enables the audio output from teacher microphone upon receiving the first IR presence signal. The wireless audio access point mutes the audio output from the teacher microphone upon failing to receive the first IR presence signal. The student microphone and the wireless audio access point establish wireless RF communication upon detection of the second IR request inquiry signal at the wireless audio access point. The wireless audio access point enables the audio output from the student microphone upon receiving the second IR presence signal. The wireless audio access point mutes the audio output from the student microphone upon failing to receive the second IR presence signal. 
         [0014]    According to a third aspect, the present invention provides a method for selectively distributing audio in a classroom using a wireless audio access point being capable of communicating over a first and second wireless RF channel and being capable of receiving a first and second IR request inquiry signals and a first and second IR presence signal. This method comprises the steps of: providing a first wireless microphone capable of communicating over the first wireless RF channel and transmitting IR signals; providing a second wireless microphone capable of communicating over the second wireless RF channel and transmitting IR signals; transmitting the first IR request inquiry signal from the first wireless microphone to the wireless audio access point; transmitting the second IR request inquiry signal from the second wireless microphone to the wireless audio access point; establishing wireless RF communication between the first wireless microphone and the wireless audio access point over the first wireless RF channel; establishing wireless RF communication between the second wireless microphone and the wireless audio access point over the second wireless RF channel; transmitting the first IR presence signal from the first wireless microphone to the wireless audio access point and second IR presence signal from the second wireless microphone to the wireless audio access point; conditionally muting audio from the first wireless microphone upon not receiving the first IR presence signal at the wireless audio access point; conditionally muting audio from the second wireless microphone upon not receiving the second IR presence signal at the wireless audio access point; conditionally enabling audio from the first wireless microphone upon receiving first IR presence signal at the wireless audio access point; and conditionally enabling audio from the second wireless microphone upon receiving the second IR presence signal at the wireless audio access point. 
         [0015]    The present invention seeks to overcome or at least ameliorate one or more of several problems, including but not limited to using two wireless RF microphones in multiple classrooms. 
       BRIEF DESCRIPTION OF DRAWINGS 
       [0016]    The accompanying figures further illustrate the present invention. 
         [0017]    The components in the drawings are not necessarily drawn to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. In the drawings, like reference numerals designate corresponding parts throughout the several views. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0018]    Prior art  FIG. 1  depicts a wireless microphone using radio frequency (RF) to transmit an audio signal to a wireless audio access point. 
           [0019]      FIG. 2  depicts a portion of a school building having several classrooms and with the wireless range of a typical wireless RF device thereupon superimposed. 
           [0020]      FIG. 3  depicts a classroom audio presentation system that uses two separate wireless RF microphones where each microphone further includes an infrared (IR) transmitter in accordance with a first illustrative embodiment of the present invention. 
           [0021]      FIG. 4  is a block diagram of a wireless microphone with an IR transmitter suitable for use with the illustrative embodiment of  FIG. 3 . 
           [0022]      FIG. 5  depicts further details of a wireless audio access point suitable for use with the illustrative embodiment of  FIG. 3 . 
           [0023]      FIG. 6  illustrates an exemplary IR request inquiry signal useful for the illustrative embodiment shown in  FIG. 3 . 
           [0024]      FIG. 7  depicts the first IR presence signal as received by the IR receiver of the wireless audio access point shown in the illustrative embodiment of  FIG. 3 . 
           [0025]      FIG. 8  depicts the first IR presence signal as transmitted by the IR receiver of the teacher microphone in accordance with a further embodiment of the present invention. 
           [0026]      FIG. 9  depicts a first IR presence signal and a second IR presence signal, each having a different digitally encoded value in accordance with an additional further embodiment of the present invention. 
           [0027]      FIG. 10  depicts a timing chart showing polling windows assigned to four microphones, which is suitable for use in an embodiment of the present invention. 
           [0028]      FIG. 11  is a flowchart of an innovative process for managing RF communications between two wireless microphones and a wireless audio access point based on the presence of IR signals. 
       
    
    
     LIST OF REFERENCE NUMBERS FOR THE MAJOR ELEMENTS IN THE DRAWING 
       [0029]    The following is a list of the major elements in the drawings in numerical order.
     10  wireless radio frequency (RF) microphone     15  wireless audio access point     21  first classroom     22  second classroom     23  third classroom     24  fourth classroom     25  fifth classroom     26  sixth classroom     27  seventh classroom     28  eighth classroom     29  ninth classroom     30  teacher microphone     34  control switch (p/o teacher microphone  30 )     40  student microphone     44  control switch (p/o student microphone  40 )     50  wireless audio access point     51  first RF digital transceiver (p/o wireless audio access point  50 )     52  second RF digital transceiver (p/o wireless audio access point  50 )     53  infrared (IR) sensor (p/o wireless audio access point  50 )     57  audio output circuitry (p/o wireless audio access point  50 )     60  microphone     61  microphone RF digital transceiver     63  microphone IR transmitter     64  microphone control switch     67  microphone element     70  IR request inquiry signal     71  synchronization (p/o IR request inquiry signal  70 )     72  microphone type (p/o IR request inquiry signal  70 )     73  scalable address (p/o IR request inquiry signal  70 )     74  error detection (p/o IR request inquiry signal  70 )     75  third microphone     80  fourth microphone     100  Bluetooth RF communication link     101  RF inquiry     102  RF inquiry response     105  polling window gap     110  flowchart     111  (step of) transmitting an IR request inquiry signal     112  (step of) establishing RF communication link     113  (step of) transmitting an IR presence signal     114  (condition) is IR presence signal missing?     115  (step of) conditionally muting audio     116  (condition) is IR presence signal still missing?     117  (step of) conditionally enabling audio     120  polling window scheme     210  range of typical wireless RF device (from classroom  21 )     300  first RF communication link (first channel)     331  first IR request inquiry signal (from teacher microphone  30 )     332  first IR presence signal (from teacher microphone  30 )     355  first polling window     400  second RF communication link (second channel)     431  second IR request inquiry signal (from student microphone  40 )     432  second IR presence signal (from student microphone  40 )     455  second polling window     705  third polling window     755  fourth polling window   P 1  first pulse period   T 1  first time period   T 2  second time period   T 3  third time period   T 4  fourth time period   T 5  fifth time period   
 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0092]    The embodiments of the present invention are described primarily in the context of a classroom audio distribution system that includes a number of wireless audio access points that may be in relatively close vicinity to one another and multiple wireless microphones. The wireless microphones and wireless audio access points establish an audio distribution system via infrared and radio frequency communication. 
       MODE(S) FOR CARRYING OUT THE INVENTION 
       [0093]    Embodiments of the present invention are described herein in the context of devices and systems which are coupled using wireless links but are not limited thereto, except as may be set forth expressly in the appended claims. 
         [0094]    Refer first to  FIG. 3  which shows a radio frequency (RF) audio distribution system including infrared (IR) presence detection in accordance with the present invention. The system includes a first wireless RF microphone, the “teacher” microphone  30 , and a second wireless RF microphone, the “student” microphone  40 . The two wireless microphones work in conjunction with a wireless communication access point, such as a “wireless audio access point”  50 . This wireless audio access point  50  is located in a position within a classroom, such as mounted on a ceiling, so that it is generally in a line of sight with all interior portions of the classroom and out of a line of sight from the interior portions of other classrooms. For example, a wireless audio access point  50  mounted on the ceiling of a first classroom  21 , as shown in  FIG. 2 , should not be visible to an occupant of a second classroom  22 . 
         [0095]    A first RF communication link  300  is established between the teacher microphone  30  and the wireless audio access point  50 . First, a teacher activates a control switch  34  on the teacher microphone  30  which causes the teacher microphone  30  to emit a first IR request inquiry signal  331 . Next, the wireless audio access point  50  detects this first IR request inquiry signal  331  at its IR sensor  53  and in response thereto transmits a RF inquiry message. Finally, the teacher microphone  30  responds with a RF inquiry response message using techniques known to those skilled in the art. Advantageously, this allows the teacher microphone  30  to only become discoverable to the wireless audio access point  50  for a very short time period. The first IR request inquiry signal  331  is particularly adapted to quickly establish RF communication between the teacher microphone  30  and the wireless audio access point  50 . In a preferred embodiment, the first IR request inquiry signal  331  includes address and device type information. 
         [0096]    A similar procedure is used to establish a second RF communication link  400  between the student microphone  40  and the wireless audio access point  50 . First, a student activates a control switch  44  on the student microphone  40  which causes the student microphone  40  to emit a second IR request inquiry signal  431 . Next, the wireless audio access point  50  detects this second IR request inquiry signal  431  at its IR sensor  53  and in response thereto transmits a RF inquiry message. Finally, the student microphone  40  responds with a RF inquiry response message using techniques known to those skilled in the art. 
         [0097]    The teacher microphone  30  and student microphone  40  may establish simultaneous communication with the wireless audio access point  50  as they establish separate RF communication channels. Each microphone transmits audio to the wireless audio access point over its respective RF communication link. A classroom  21  equipped with the inventive RF audio distribution system described in  FIG. 3  enables more effective communication between teacher and students and thus creates an environment more conducive to learning. The teacher microphone  30  helps the teacher convey her message more clearly and the student microphone  40  allows for improved class participation. 
         [0098]    The student microphone  40  may be passed throughout the classroom as students take turns participating in the class discussion. Alternatively, those skilled in the art will recognize that a system of this type is not limited to two microphones. Alternative embodiments of the RF audio distribution system may employ multiple student microphones dispersed throughout a classroom. In addition, those skilled in the art will recognize that the teacher microphone  30  and student microphone  40  may be equipped with control buttons. Control buttons on the teacher microphone may provide the teacher the ability to selectively allow students to participate in class discussions by muting or enabling their microphones. In alternative embodiments of the invention students may use control buttons to mark their attendance, to answers interactive quizzes and polls, and to indicate willingness to volunteer. 
         [0099]    During operation it is advantageous to determine whether the teacher  30  or student microphones  40  have been moved out of the present classroom. The wireless audio access point  50  detects the continued presence of the teacher microphone  30  and student microphone  40  by verifying that the microphone is within the same classroom as the IR sensor  53 , by causing the teacher microphone  30  to transmit a first IR presence signal  332  and by causing the student microphone to transmit a second IR presence signal  432 . 
         [0100]    Those skilled in the art will recognize that the inventive technique of using an IR signal to establish a RF communication link to avoid having to remain discoverable to extraneous RF devices can be extended to other wireless communication systems and various other portable wireless devices. 
         [0101]    Refer to  FIG. 4  which shows an exemplary block diagram of certain functional blocks common to both the teacher microphone  30  and the student microphone  40 . The primary functional blocks shown include a RF digital transceiver  61 , an IR transmitter  63 , and a control switch  64 . In addition to these functional blocks, the microphones include an antenna associated with the RF digital transceiver  61 , a microphone element  67  and associated audio input circuitry, and processing and memory elements typically found in modern electronic equipment. 
         [0102]    Now refer to  FIG. 5 , which shows a block diagram of certain functional blocks within an exemplary wireless audio access point  50 . The primary functional blocks shown include two separate RF digital transceivers  51  and  52  and an IR sensor  53  that provide the functionality previously described above. In addition to these functional blocks, the wireless audio access point  50  includes two antennas, each associated with a corresponding RF digital transceiver, audio output circuitry  57 , and other processing and memory elements typically found in modern electronic equipment. 
         [0103]    In the embodiment shown in  FIG. 3 , the first IR request inquiry signal  331  and second IR request inquiry signal  431  may be particularly adapted to quickly establish wireless RF communication between the wireless audio access point  50  and the teacher microphone  30  or student microphone  40 . Particularly, by providing the microphone&#39;s scalable address in an IR request inquiry signal, the wireless audio access point may immediately begin the RF pairing process. The scalable address of the teacher microphone  30  or student microphone  40  is a unique pre-assigned value that identifies the particular microphone. Transmittal of the scalable address to the wireless audio access point  50  is a prerequisite for establishing a RF communication link between a microphone and the wireless audio access point  50 . In addition to the scalable address, the IR request inquiry signals may also include information relating to microphone type, synchronization data and error detection or detection data. 
         [0104]    Refer now to  FIG. 6 , which illustrates the components of an exemplary IR request inquiry signal  70 . The IR request inquiry signal  70  is comprised of forty-eight (48) bits, divided into four component bit strings. The first eight (8) bits  71  are a predetermined pattern used for time synchronization. The synchronization pattern is recognized by the wireless audio access point  50  and identifies to the wireless audio access point  50  that the signal is a valid IR request inquiry signal. The second eight (8) bits  72  identify the model type of the microphone transmitting the IR signal. Those skilled in the art will recognize that different models of microphones with different functions and attributes may be used in the RF audio distribution system. Each model is assigned an eight (8) bit identification number by the manufacturer and the IR request inquiry signal communicates this identification number to the wireless audio access point  50 . The next twenty-four (24) bits  73  provide the wireless audio access point  50  with the microphone&#39;s  30  scalable address, as described above. The final eight (8) bits provide error detection data  74 . Those skilled in the art will recognize that various error detection or error correction schemes may be used, such as by computing a checksum, a parity bit or a cyclic redundancy check. 
         [0105]    Now refer to  FIG. 7  which illustrates the first IR presence signal  332  as received by the IR sensor  53  of the wireless audio access point  50 . Due to noise in the environment and the transmission properties of IR signals, the IR sensor  53  detects a noisy pulse, not a perfect square pulse. In embodiments of the present invention, the wireless audio access point  50  is designed to sense a rise in the intensity of IR light above the ambient noise. The IR sensor  53  of the wireless audio access point  50  continuously samples the light intensity at the wavelength of the IR signal and computes a running average of the background intensity for a relevant time period. The wireless audio access point  50  uses this background intensity average as a reference point to detect pulses of IR light above background levels, such as in an automatic gain control system. 
         [0106]    Advantageously, because the IR sensor  53  is able to detect a noisy pulse, the RF audio distribution system does not require a direct line of sight between the IR transmitter  63  and IR sensor  53 . The IR sensor  53  needs simply to detect a rise in IR light intensity to detect the first IR presence signal  332 . As long as the teacher microphone  30  or student microphone  40  is collocated in a room with the wireless audio access point  50 , the first IR presence signal  332  or second IR presence signal  432 , respectively, will be detected by the IR sensor  53 . 
         [0107]    In an embodiment of the present invention, the teacher microphone  30  and the student microphone  40  transmit the first IR presence signal  332  and second IR presence signal  432  in response to requests from the wireless audio access point  50 . The wireless audio access point  50  periodically sends this request to the teacher microphone  30  and student microphone  40  over the first RF communication link  300  or second RF communication link  400 , respectively. The wireless audio access point  50  prompts one microphone at time as a means of distinguishing from which microphone an IR presence signal originated. After sending a request for an IR presence signal, the wireless audio access point  50  waits to detect an increase in IR light intensity above the background noise for a predetermined epoch of time. 
         [0108]    In alternative embodiments of the invention, the teacher microphone  30  and student microphone  40  periodically transmit the first IR presence signal  332  and second IR presence signal  432  without a prompt from the wireless audio access point  50 . To distinguish between the first IR presence signal  332  and second IR presence signal  432 , the two presence signals have a distinguishing characteristic such as a unique value digitally encoded on the signal or a unique pulse period. This distinguishing characteristic may be preprogrammed in the microphone and communicated to the wireless audio access point  50  during the pairing process or it may be assigned by the wireless audio access point  50  during the initial pairing process. 
         [0109]    Now refer to  FIG. 8  which depicts the first IR presence signal  331  having a first pulse period P 1  as transmitted by the teacher microphone ( 30 ). In alternative embodiments of the present invention as described above, the wireless audio access point  50  assigns a different pulse period to the teacher microphone  30  and the student microphone  40  in order to distinguish from which microphone a received IR presence signal originated. For example, the wireless audio access point  50  may assign the first pulse period P 1  to the teacher microphone  30  and a second pulse period to the student microphone  40 . The teacher microphone  30  would then periodically transmit the first IR presence signal  332  for the first pulse period P 1  without prompt from the wireless audio access point  50 . The student microphone would periodically transmit the second IR presence signal  432  for the second pulse period without prompt from the wireless audio access point  50 . The wireless audio access point  50  determines which microphones are collocated in a room with it by distinguishing between the pulse periods of the IR presence signals. 
         [0110]    Refer now to  FIG. 9  which illustrates the first IR presence signal  332  and second IR presence signal  432  having different values digitally encoded thereon. In an alternative embodiment of the present invention, the wireless audio access point  50  assigns a first value to the teacher microphone  30  and a second value to the student microphone  40  during the initial pairing process. The teacher microphone  30  digitally encodes this first value onto the first IR presence signal  332  and the student microphone  40  digitally encodes the second value onto to the second IR presence signal  432 . The teacher microphone  30  and student microphone  40  transmit their IR presence signals periodically with no prompt from the wireless audio access point  50 . The wireless audio access point  50  determines which microphone is collocated in a room with it by distinguishing between the values digitally encoded on the IR presence signals. Those skilled in the art will recognize that the teacher microphone  30  or student microphone  40  will now require a direct line of sight to the wireless audio access point  50  for the IR sensor  53  to discern the digital transitions of their respective IR presence signal. 
         [0111]    In an embodiment of the present invention, the wireless audio access point  50  sets a polling window scheme  120  for the microphones to follow.  FIG. 10  depicts a timing chart showing the polling window assigned to each microphone. The timing chart depicted in  FIG. 10  pertains to a wireless audio distribution system comprising a teacher microphone  30 , a student microphone  40 , a third microphone  75 , and a fourth microphone  80 . In the polling window scheme  120 , a predetermined time period is divided into a number of polling windows corresponding to the number of microphones present in the wireless audio distribution system. In the polling window scheme  120  illustrated in  FIG. 10 , the predetermined time period is divided into a first polling window  355 , a second polling window  455 , a third polling window  705 , and a fourth polling window  755 . There is a polling window gap  105  after each polling window. For example, if the predetermined time period of the polling window scheme is five (5) minutes. The wireless audio access point  50  may divide the five (5) minute time period into four (4) polling windows, each one (1) minute long with four polling window gaps  105  of fifteen (15) seconds. 
         [0112]    The teacher microphone  30  is assigned the first polling window  355  by the wireless audio access point  50  and may only transmit the first IR presence signal  332  during this first polling window  355 . There is no longer a need to differentiate IR presence signals by microphone because only the teacher microphone may transmit an IR presence signal during the first presence signal window and all IR presence signals received by the wireless audio access point  50  during the first polling window  355  are attributed to the teacher microphone  41 . Similarly, as assigned by the wireless audio access point  50 , the second polling window  455  is the exclusive domain for the student microphone  40  to transmit an IR presence signal, the third polling window  705  is the exclusive domain for a third microphone  75  to transmit an IR presence signal, and the fourth polling window  755  is the exclusive domain for a fourth microphone  80  to transmit an IR presence signal. After the fourth polling window  755  has elapsed, the polling window scheme repeats  120  as necessary. Therefore each microphone transmits one IR presence signal for each iteration of the polling window scheme  120 . 
         [0113]    The polling window scheme  120  may be assigned by the wireless audio access point  50  to accommodate particular schedules. For example, in a school setting, the entire sequence may repeat every five (5) minutes to ensure that a new iteration begins at the start of every hour, a common time for class periods to begin. The time period may be set at a shorter interval to take into account applications where microphones quickly move into and out of classrooms. In addition, the number of polling windows may be set at a preconfigured number or it may vary depending on the number of microphones. 
         [0114]      FIG. 11  shows a process flowchart  110  for selectively communicating with a student microphone  30  and a teacher microphone  40  as they move throughout a school. Those skilled in the art will recognize that the present invention is also suitable for use in other predefined areas, such as, but not limed to: conference centers and hotels. According to the present invention, the predefined area includes a number of wireless audio access points within the area. 
         [0115]    Flowchart  110  includes processes of the present invention which, in one embodiment, are carried out by a processor and electrical components under the control of computer readable and computer executable instructions. The computer readable and computer executable instructions may reside, for example, in data storage features such as computer usable memory or in any other type of computer readable medium. Although specific steps are disclosed in flowchart  110 , such steps are exemplary. That is, the present invention is well suited to performing various other steps or variations of the steps recited in  FIG. 11 . Within the present embodiment, it should be appreciated that the steps of flowchart  110  can be performed by software or hardware or any combination of software and hardware. 
         [0116]    Refer now to  FIG. 11  and refer back to  FIG. 4 . According to an illustrative embodiment of the present invention, a first RF communication link  300  is established between the teacher microphone  30  and the wireless audio access point (step  112 ) only after the teacher microphone  30  has transmitted (step  111 ) a first IR request inquiry signal  331  and this IR signal has been received at the wireless audio access point  50 . Establishing (step  112 ) the first RF communication link  300  entails the wireless audio access point  50  transmitting a RF inquiry message and the teacher microphone  30  transmitting a RF inquiry response message. As described above, the IR signal may be transmitted (step  111 ) in response to an operator action. 
         [0117]    A second RF communication link  400  is established between the student microphone  40  and the wireless audio access point  50  in a manner similar to that of the first RF communication link  300 . The second RF communication link  400  is established only after the student microphone  40  has transmitted (step  111 ) a second IR request inquiry signal  431  and this second IR request inquiry signal  431  has been received at the wireless audio access point  50 . Establishing (step  112 ) the second RF communication link  400  entails the wireless audio access point  50  transmitting a RF inquiry message and the student microphone  40  transmitting a RF inquiry response message. 
         [0118]    In a preferred embodiment of the present invention, the teacher microphone  30  transmits (step  113 ) a first IR presence signal  332  and the student microphone  40  transmits (step  113 ) a second IR presence signal  432  upon request. Advantageously, due to the propagation nature of the IR signal this allows the wireless audio access point  50  to determine whether the student microphone or the teacher microphone are within the confines of the same classroom. 
         [0119]    Those skilled in the art will recognize it is desirable to conditionally mute the audio from the wireless microphones when, for example a teacher giving a lecture in a first classroom steps out of that classroom. Accordingly, to determine whether the teacher microphone  30  is still collocated; the wireless audio access point  50  periodically requests that the teacher microphone  30  transmit (step  113 ) the first IR presence signal  332 . If the first IR presence signal  332  is not received (i.e. ‘missing’) at the wireless audio access point  50  and more specifically at IR Sensor  53 , then the audio from the teacher microphone  30  is muted (step  115 ). Note that the associated audio data stream is still being transmitted from the teacher microphone  30  to the wireless audio access point  50 , but is being muted in the audio output circuitry  57 , shown in  FIG. 5 . 
         [0120]    Next, the wireless audio access point  50  continues to request for the teacher microphone  30  to transmit the first IR presence signal  332 . In certain embodiments the wireless audio access point  50  will request that the first IR presence signal  332  be transmitted at a ‘high power’ setting to aid collocation. If, after periodic retries, requests for higher power settings, and the like, the first IR presence signal  332  is now detected, then the audio from teacher microphone  30  is enabled (step  117 ). 
         [0121]    The wireless audio access point  50  manages communication with the student microphone  40  in a similar manner. To determine whether the student microphone  40  is still collocated; the wireless audio access point  50  periodically requests that the student microphone  40  transmit (step  113 ) the second IR presence signal  432 . If the second IR presence signal  432  is not received (i.e. ‘missing’) at the wireless audio access point  50  and more specifically at IR Sensor  53 , shown in  FIG. 5 , then the audio from the student microphone  40  is conditionally muted (step  115 ). Note that the associated audio data stream is still being transmitted from the student microphone  40  to the wireless audio access point  50 , but is being muted in the audio output circuitry  57 , shown in  FIG. 5 . 
         [0122]    Next, the wireless audio access point  50  continues to request that the student microphone  40  transmit the second IR presence signal  432 . In certain embodiments the wireless audio access point  50  will request that the second IR presence signal  432  be transmitted at a ‘high power’ setting so that collocation can be determined even if the IR transmitter  423  is not in a direct line-of-sight with the IR sensor  53 . If, after periodic retries, requests for higher power settings, and the like, the second IR presence signal  432  is now detected, then the audio from student microphone  40  is enabled (step  117 ). 
         [0123]    Those skilled in the art will realize that it is beneficial to conditionally mute and enable audio from the student microphone  40  depending on whether the student is collocated with a wireless audio access point  50 . Audio will cease to be distributed if the student is no longer in the classroom to avoid extraneous conversations from being broadcast to the classroom. Additionally, by conditionally enabling only those microphones that are collocated in the same room as the wireless audio access point  50 , students may have personal microphones that are operable in multiple classrooms as opposed to having microphones assigned to a specific room. 
         [0124]    In summary, embodiments of the present invention provide a user-friendly system and method for using two wireless microphones in multiple classrooms while monitoring whether the wireless microphones are collocated in a classroom with a wireless audio access point while preventing undesired or extraneous audio. 
       INDUSTRIAL APPLICABILITY 
       [0125]    To solve the aforementioned problems, the present invention includes a method for intelligently selecting a wireless RF access point from a plurality of available points. 
       LIST OF ACRONYMS USED IN THE DETAILED DESCRIPTION OF THE INVENTION 
       [0126]    The following is a list of the acronyms used in the specification in alphabetical order.
   IEEE Institute of Electronic and Electrical Engineers   IR infrared   ms millisecond   RF radio frequency   VoIP Voice over Internet Protocol   
 
       ALTERNATE EMBODIMENTS 
       [0132]    Alternate embodiments may be devised without departing from the spirit or the scope of the invention. For example, certain embodiments may use digital RF communication protocols such as Bluetooth or Wi-Fi Direct or other audio transmission methods such as Voice over Internet Protocol (VoIP).