Patent Publication Number: US-7224938-B2

Title: Method of communicating with a network device

Description:
FIELD OF THE INVENTION 
     The present invention relates in general to the operation of a wireless network, and more particularly to a method of allowing a device outside of a network request and facilitate communication with a device inside the network. 
     BACKGROUND OF THE INVENTION 
     Some wireless networks are centrally controlled, with a single device coordinating the operation of all of the devices in the network. This central coordinator provides instructions to each of the devices regarding transmission times, power levels, and the like. One example of this sort of network is a piconet using the proposed IEEE 802.15.3 standard. 
     In such a centrally-controlled network, all of the devices in the network must be able to both send and receive data from the central coordinator. Any device that cannot reliably communicate with the central coordinator of a network cannot join the network. 
     This means that a local device that can physically communicate reliably with a target device (i.e., it is within operational range of the target device) might not be able to effectively communicate with that target device if the target device is already in a network. In such a case, the local device would have to also be able to communicate with the central coordinator to be assigned the necessary channel time for such a communication. 
     If the local device can&#39;t communicate with the central coordinator, then it won&#39;t be able to join the same network that the target device is in to ask to speak to that device. And since the coordinator allocates resources for communication in the network, if the local device is not in the same network as the target device, then the target device will never be assigned any time to communicate with the local device. 
     In some protocols the target device could create a child network within the main network it belongs to facilitate communication with the local device. In this case the target device would take on the properties of the central coordinator with respect to that child network, and its limits of communication would set the boundaries of the child network. Once the child network was started, the local device could become a member of that child network and request communication with the target device. 
     However, with current networks, there is no way for the target device to know that there is another device looking to communicate with it. And absent the knowledge that there was another device that would benefit from the creation of a child network, the target device has no reason to start such a child network. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying figures where like reference numerals refer to identical or functionally similar elements and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate an exemplary embodiment and to explain various principles and advantages in accordance with the present invention. 
         FIG. 1  is a block diagram of a wireless network according to a disclosed embodiment of the present invention; 
         FIG. 2  is a block diagram of a TDMA scheme including superframes, according to a disclosed embodiment of the present invention; 
         FIG. 3  is a block diagram of a wireless network and adjacent orphan device according to a disclosed embodiment of the present invention; 
         FIG. 4  is a block diagram of a wireless network and a neighbor wireless network according to a disclosed embodiment of the present invention; 
         FIG. 5  is a block diagram of a wireless network including a child wireless network according to a disclosed embodiment of the present invention; 
         FIG. 6  is a block diagram of a probe command according to a disclosed embodiment of the present invention; 
         FIG. 7  is a block diagram of a child network desired information element according to a disclosed embodiment of the present invention. 
         FIG. 8  is a flow chart of the operation of a network device using a probe command according to a disclosed embodiment of the present invention; 
         FIG. 9  is a flow chart of the operation of an orphan device receiving a probe command according to a disclosed embodiment of the present invention; 
         FIG. 10  is a flow chart of the operation of an orphan device using an adjacent network according to a disclosed embodiment of the present invention; and 
         FIG. 11  is a flow chart of the operation of a network device in a first network scanning an adjacent network according to a disclosed embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The instant disclosure is provided to further explain in an enabling fashion the best modes of performing one or more embodiments of the present invention. The disclosure is further offered to enhance an understanding and appreciation for the inventive principles and advantages thereof, rather than to limit in any manner the invention. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued. 
     It is further understood that the use of relational terms such as first and second, and the like, if any, are used solely to distinguish one from another entity, item, or action without necessarily requiring or implying any actual such relationship or order between such entities, items or actions. It is noted that some embodiments may include a plurality of processes or steps, which can be performed in any order, unless expressly and necessarily limited to a particular order; i.e., processes or steps that are not so limited may be performed in any order. 
     Much of the inventive functionality and many of the inventive principles when implemented, are best supported with or in software or integrated circuits (ICs), such as an embedded processor and software therefore or application specific ICs. It is expected that one of ordinary skill, notwithstanding possibly significant effort and many design choices motivated by, for example, available time, current technology, and economic considerations, when guided by the concepts and principles disclosed herein will be readily capable of generating such software instructions or ICs with minimal experimentation. Therefore, in the interest of brevity and minimization of any risk of obscuring the principles and concepts according to the present invention, further discussion of such software and ICs, if any, will be limited to the essentials with respect to the principles and concepts used by the exemplary embodiments. 
     Wireless Network 
       FIG. 1  is a block diagram of a wireless network  100  according to a disclosed embodiment of the present invention. In this embodiment the network  100  is a wireless personal area network (WPAN), or piconet. However, it should be understood that the present invention also applies to other settings where bandwidth is to be shared among several users, such as, for example, wireless local area networks (WLAN), or any other appropriate wired or wireless network. 
     When the term piconet is used, it refers to a wireless network of devices connected in an ad hoc fashion, having one device act as a coordinator (i.e., it functions as a master) while the other devices (sometimes called stations) follow the time allocation instructions of the coordinator (i.e., they function as slaves). The coordinator can be a designated device, or simply one of the devices chosen to function as a coordinator. One primary difference between the coordinator and non-coordinator devices is that the coordinator must be able to communicate with all of the devices in the network, while the various non-coordinator devices need not be able to communicate with all of the other non-coordinator devices. 
     As shown in  FIG. 1 , the network  100  includes a coordinator  110  and a plurality of devices  121 – 125 . The coordinator  110  serves to control the operation of the network  100 . As noted above, the system of coordinator  110  and devices  121 – 125  may be called a piconet, in which case the coordinator  110  may be referred to as a piconet coordinator (PNC). Each of the non-coordinator devices  121 – 125  must be connected to the coordinator  110  via primary wireless links  130 , and may also be connected to one or more other non-coordinator devices  121 – 125  via secondary wireless links  140 , also called peer-to-peer links. 
     In addition, although  FIG. 1  shows bi-directional links between devices, they could also be shown as unidirectional links. In this case, each bi-directional link  130 ,  140  could be shown as two unidirectional links, the first going in one direction and the second going in the opposite direction. 
     In some embodiments the coordinator  110  may be the same sort of device as any of the non-coordinator devices  121 – 125 , except with the additional functionality for coordinating the system, and the requirement that it communicates with every device  121 – 125  in the network  100 . In other embodiments the coordinator  110  may be a separate designated control unit that does not function as one of the devices  121 – 125 . 
     In some embodiments the coordinator  110  will be a device just like the non-coordinator devices  121 – 125 . In other embodiments the coordinator  110  could be a separate device dedicated to that function. Furthermore, individual non-coordinator devices  121 – 125  could include the functional elements of a coordinator  110 , but not use them, functioning as non-coordinator devices. This could be the case where any device is a potential coordinator  110 , but only one actually serves that function in a given network. 
     Each device of the network  100  may be a different wireless device, for example, a digital still camera, a digital video camera, a personal data assistant (PDA), a digital music player, a laptop personal computer, a desktop personal computer, or other personal wireless device. 
     The various non-coordinator devices  121 – 125  are confined to a usable physical area  150 , which is set based on the extent to which the coordinator  110  can successfully communicate with each of the non-coordinator devices  121 – 125 . Any non-coordinator device  121 – 125  that is able to communicate with the coordinator  110  (and vice versa) is within the usable area  150  of the network  100 . As noted, however, it is not necessary for every non-coordinator device  121 – 125  in the network  100  to communicate with every other non-coordinator device  121 – 125 . 
     Although a wireless network is described with reference to  FIG. 1 , and the disclosure refers to this wireless network by way of example, the current claimed invention is equally applicable to wired networks. By way of example the present claimed invention could be applied to wireless networks of the sort defined by the IEEE 802.11 standard or the IEEE 803.15.3 standard, the proposed IEEE 802.15.3b standard, by a wired Ethernet network, or to any other suitable wired or wireless network. 
     Superframes 
     The available bandwidth in a given network  100  may be split up in time by the coordinator  110  into a series of repeated superframes. These superframes define how the available transmission time is split up among various tasks. Individual frames of data are then transferred within these superframes in accordance with the timing set forth in the superframe. 
       FIG. 2  is a block diagram of a TDMA scheme including superframes and channel time allocations according to a disclosed embodiment of the present invention. As shown in  FIG. 2 , the available transmission time  200  is broken up into a plurality of consecutive superframes  210 . Each individual superframe  210  in this embodiment includes a beacon period  220 , a contention access period (CAP)  230 , and a contention free period (CFP)  240 . The contention free period  340  is further broken up into a plurality of channel time allocations (CTAs)  250  (also called time slots). 
     The beacon period  220  is set aside for the coordinator  110  to send a beacon frame out to the non-coordinator devices  121 – 125  in the network  100 . Such a beacon frame will include information for organizing the operation of devices within the superframe  210 . Each non-coordinator device  121 – 125  knows how to recognize a beacon period  220  prior to joining the network  100 , and uses the beacon  220  both to identify an existing network  100  and to coordinate communication within the network  100 . 
     The beacon frame provides information required by the devices  121 – 125  in the network  100  regarding how the individual channel time allocations  250  will be allocated. In particular, it notes how and when devices  110 ,  121 – 125  can transmit to prevent any two devices from interfering. 
     The CAP  230  is used to transmit commands or asynchronous data across the network  100 . The CAP  230  may be eliminated in many embodiments and the system would then pass commands solely during the CFP  240 . 
     The CFP  240  includes a plurality of channel time allocations  250 . These channel time allocations  250  are each assigned by the coordinator  110  to one or more transmitting devices  110 ,  121 – 125  and one or more receiving devices  110 ,  121 – 125  for transmission of information between them. Generally each transmitting device will have a single associated receiver, through in some cases a single transmitter will transmit to multiple receivers at the same time. 
     The channel time allocations  250  are provided to allow communication between devices  120 ,  121 – 125 . They do so in accordance with the information set forth in the beacon  220 . The size of the channel time allocations  250  can vary by embodiment, but it should be large enough to transmit one or more data frames. 
     Although the embodiments described in this document are in the context of a WPAN (or piconet), it should be understood that the present invention also applies to other settings where bandwidth is to be shared among several users, such as, for example, wireless local area networks (WLAN), other appropriate wireless network, or any wired or wireless transmission scheme in which bandwidth must be shared. 
     The superframes  210  are fixed time constructs that are repeated in time. The specific duration of the superframe  210  is described in the beacon  220 . In fact, the beacon  220  generally includes information regarding how often the beacon  220  is repeated, which effectively corresponds to the duration of the superframe  210 . The beacon  220  also contains information regarding the network  100 , such as the identity of the transmitters and receivers assigned to each channel time allocation  250 , the necessary transmission parameters for signals within a channel time allocation  250 , and the identity of the coordinator  110 . 
     The system clock for the network  100  is preferably synchronized through the generation and reception of the beacons  220 . Each non-coordinator device  121 – 125  will store a synchronization point time upon successful reception of a valid beacon  220 , and will then use this synchronization point time to adjust its own timing. 
     Communication with an Orphan Device 
     As noted above, every non-coordinator device  121 – 125  in a network  100  must be able to communicate with the network coordinator  110 . Devices outside the usable area  150  of the network  100  (i.e., outside the communication range of the network coordinator  110 ) cannot join the network  100 . Unfortunately this means that even if a device outside the usable area  150  of the network  100  is within communication range of its target device, it can&#39;t request communication time with the target device. A remote device in such a situation can be referred to as an orphan device. 
       FIG. 3  is a block diagram of a wireless network and adjacent orphan device according to a disclosed embodiment of the present invention. As shown in  FIG. 3 , the disclosed environment includes a first network coordinator  310 , a first non-coordinator device  320 , a second non-coordinator device  330 , a third non-coordinator device  340 , and a fourth orphan device  360 . For ease of description, the first network coordinator  310  will be referred to as the first coordinator  310 , the first through third non-coordinator devices  320 – 340  will be referred to as the first through third devices  320 – 340 , and the fourth orphan device  360  will be referred to as the orphan device  360 . 
     The first coordinator  310  and the first through third devices  320 – 340  form a first network under the control of the first coordinator  310 . This network has a first usable area defined by a first communication limit  350  of the first coordinator  310 . 
     The first coordinator  310  provides instructions for the operation of the first though fourth devices  320 – 340 , and receives various management information from the first though fourth devices  320 – 340 . As a result, each of these devices must operate within the first communication limit  350 . 
     The orphan device  360  has a second communication limit  370  that represents the limits of its own communication capability. In this disclosed embodiment the orphan device  360  is located outside of the first communication limit  350  and the first coordinator  310  is located outside of the second communication limit  370 . As a result, neither can communicate with the other, and so the orphan device  360  cannot join the first network. 
     However, in this disclosed embodiment the third non-coordinator device  340  is located within the second communication limit  370 . As a result, the third non-coordinator device  340  and the orphan device  460  are physically capable of communication with each other. But before such communication can occur, the two must both join the same network and have the coordinator of that new network provide the parameters of such communication. Since the disclosed protocol is one with centralized control, the only way devices can pass data is as directed by a network coordinator. 
     Thus, if the fourth device  360  wants to communicate with the third device  340 , it has two main options: it can create its own network and invite the third device  340  to join; or it can convince the third device  340  to create a child network within the first network and then invite the fourth device  360  to join. Examples of these two options are shown in  FIGS. 4 and 5 . 
       FIG. 4  is a block diagram of a wireless network and a neighbor wireless network according to a disclosed embodiment of the present invention. As shown in  FIG. 4 , the disclosed environment includes a first coordinator  310 , first through third devices  320 – 340 , and a second network coordinator  460 . 
     The first coordinator  310  and the first through third devices  320 – 340  operate just as they were disclosed above with respect to  FIG. 3 . However in this embodiment, the orphan device  360  takes on the role of the second coordinator  460 , and creates a second network using a different channel 
     The second coordinator  460  can then communicate with the third device  340  via the beacon in the second network, either inviting the third device  340  to join the second network, or requesting that the third device set up a child network and invite the second coordinator  460  (i.e., the orphan device  360 ) to join. 
     Because the first coordinator  310  and the second coordinator  460  cannot communicate with each other, the first and second network must operate on different channels to avoid interference with each other. Although a mechanism of neighboring networks may exist, allowing adjacent networks to share a single channel, such a structure would require the two network coordinators  310  and  460  to be able to pass data to arrange the sharing of the channel. 
     Furthermore, because no device can be under the primary control of two coordinators at the same time, if the third device  340  joined the second network, it would have to leave the first network to do so. However, the third device  340  could listen to the beacon in the second network during a channel scan without leaving the first network. 
       FIG. 5  is a block diagram of a wireless network including a child wireless network according to a disclosed embodiment of the present invention. As shown in  FIG. 5 , the disclosed environment includes a first coordinator  310 , first and second devices  320  and  330 , a third coordinator  540 , and an orphan device  360 . 
     The first coordinator  310 , the first and second devices  320  and  330 , and the orphan device  360  operate just as they were disclosed above with respect to  FIG. 3 . However in this embodiment, the third device  340  takes on the role of the third coordinator  540 , and creates a child network within the first network. In this case the third coordinator  540  has a third communication limit  380  that represents the limits of its own communication capability. 
     The child network operates under the ultimate control of the first coordinator  310 , granting the child network a portion of channel time in the first network. The third coordinator  540  can then run that allocated channel time as it sees fit. Since the orphan device  360  is within the third communication limit  380  of the third coordinator  540  (and the third coordinator  540  is presumably within a communication limit of the orphan device  360 ), the third coordinator  540  can invite the orphan device  360  to join the child network, allowing the third coordinator  540  (i.e., the third device  340 ) and the orphan device  360  to communicate. 
     What is necessary, however, in either of these embodiments is for the third device  340  to recognize the presence of the orphan device  360  and its desire to communicate. This can be accomplished in a number of ways, two of which are described by way of example. 
     First, the third device  340  could periodically send out a probe command looking for orphan devices. This probe command can be addressed to set device address that will ensure that devices in the network and devices outside of the network that can hear the network coordinator will not respond. And unlike a typical probe command, this can be sent with an immediate acknowledgement policy. Second, the orphan device  360  could form a second network as a second coordinator  460 , and send out a request in its beacon for the third device  340  to form a child network (e.g., it could send a child network desired information element in its beacon). 
       FIG. 6  is a block diagram of a probe command according to a disclosed embodiment of the present invention. As shown in  FIG. 6 , the probe command  600  includes a network identifier  610 , a probe target identifier  620 , an acknowledgement (ACK) policy indicator  630 , and other information  620 . 
     The network identifier  610  provides the network identifier of the network for which the device transmitting the probe command  600  belongs. Although this information will not necessarily be if use to an orphan device responding to the probe command  600 , it is useful in preventing devices that can contact the network coordinator (and thus are not properly orphan devices) from responding. 
     The probe target identifier  620  provides the device identifier for the device or group of devices that the probe command is targeted at. In the disclosed embodiment the probe target identifier  620  uses a device identifier that is used to represent unassigned devices. 
     The ACK policy indicator  620  indicates what the acknowledgement policy of the command should be. This can include no-acknowledgment, immediate-acknowledgement, or delayed-acknowledgment. In this situation, the probe command uses an immediate-acknowledgement policy, allowing orphan devices to respond to the probe. In alternate embodiments in which multiple orphan devices are expected, a slotted Aloha or a carrier sense multiple access with collision avoidance (CSMA/CA) system of acknowledgement could be used to avoid acknowledgement collisions. 
     The other information  630  can include an indicator of the command type, an indicator of the length of the probe command  600 , or anything else that the network requires. In particular, the probe command can include a header identifying the source device for the transmission. 
     When a probe command is sent out to the unassigned address using an immediate acknowledgement policy, only devices that are both unassigned (i.e., not in the network) and cannot hear the beacon associated with the network identifier  610  (i.e., they are out of the usable area of the network) may respond. These are the orphan devices that might desire to communicate with the device, but cannot join the network because they cannot hear the network coordinator. 
     If a device that sends out a probe command  600  receives an immediate acknowledgement to that command, it will know that there is an orphan device nearby that wishes to communicate and can request that its network coordinator allow it to form a child network. Once the child network is formed, the orphan device can associate with the child network and communication can commence. 
       FIG. 7  is a block diagram of a child network desired information element according to a disclosed embodiment of the present invention. As shown in  FIG. 7 , the child network desired information element includes a network device identifier  710  and other information  730 . 
     The network device identifier  710  provides the device identifier for one or more devices that the orphan device would like to communicate with. 
     The other information  720  can include an element identifier, an indicator of the length of the child network desired information element  700 , or anything else that the network requires. 
     As noted above, when an orphan device desires to communicate with a network device, it can create its own network on a different channel from the adjacent network, and send out a child network desired information element  700  in its beacon. Although the network device (or devices) will not hear this beacon normally, it will periodically perform a channel scan to locate adjacent networks. During such a scan, the network device will find the new network, hear its beacon, and receive the child network desired information element  700 . The network device will then know that there is an orphan device nearby that wishes to communicate and can request that its network coordinator allow it to form a child network. Once the child network is formed, the orphan device can end its own network and associate with the child network so that communication can commence. 
     Operation of a Device in a Network Using a Probe Command 
       FIG. 8  is a flow chart of the operation of a network device using a probe command according to a disclosed embodiment of the present invention. 
     As shown in  FIG. 8 , the operation  800  starts when the network device sends a probe command  600  to the unassigned address seeking for devices looking to communicate. ( 810 ) This probe command  600  will be sent using an immediate-acknowledgment policy. 
     The network device will then determine whether it has received an acknowledgement to the probe command within an allowable time. ( 820 ) 
     If no acknowledgement is received, the network device will assume that there are no adjacent orphan devices desiring communication and will continue with normal processing until it is time to send out the next probe command ( 830 ), at which time the operation  800  will begin again by sending a probe command. ( 810 ) The frequency of the transmission of the probe command can vary as needed by the network. Greater frequency will cost more in overhead, but will allow orphan devices to be identified sooner, while lower frequency will cost less in overhead, but will increase the chance that orphan devices will have to wait before they can communicate. 
     If the network device did receive an acknowledgment to its probe command then it knows that there is an adjacent orphan device that desires to communicate with it. It can then request the network controller to allow it to create a child network. ( 840 ) 
     Then the network device must determine if its request is approved. ( 850 ) If the request is not approved, it will continue with normal processing until it is time to send out the next probe command ( 830 ), at which time the operation  800  will begin again. ( 810 ) If the request is approved, the network device will create a child network and allow new devices to associate. ( 860 ) Since the orphan device must be able to communicate with the network device (else it never would have received the probe command, nor would the network device have received the acknowledgement), it should have no trouble associating with the child network and communication can begin. 
     In particular, a disclosed method of operating a network device in a wireless network may include: joining the wireless network; transmitting a probe command after joining the wireless network, the probe command being addressed to a reserved device identifier; listening for an acknowledgement to the probe command from an orphan device; and sending a management transmission to a network controller requesting the creation of a child network if an acknowledgement to the probe command is received. 
     The method may further comprise: receiving a controller transmission from the network controller granting permission to create the child network; creating the child network; and allowing an outside device to join the child network. 
     The probe command may use one of: an immediate acknowledgement policy a slotted Aloha acknowledgement policy, and a carrier sense multiple access with collision avoidance acknowledgement policy. The reserved device identifier may be an unassigned device identifier that specifically references devices that have not been assigned individual device identifiers. 
     The network device may periodically repeat the transmitting of the probe command and the listening for an acknowledgement to the probe command. In particular, the network device may transmit the probe command in one of: a regularly-scheduled channel time allocation assigned to the network device; a management channel time allocation assigned to the network device; a specifically-requested channel time allocation assigned to the network device; and a contention access period. 
     The method may be implemented in an ultra wideband device. The method may also be implemented in an integrated circuit. 
     Operation of an Orphan Device Receiving a Probe Command 
       FIG. 9  is a flow chart of the operation of an orphan device receiving a probe command according to a disclosed embodiment of the present invention. 
     As shown in  FIG. 9 , the operation  900  starts when the orphan device scans for nearby devices ( 905 ) and determines whether any devices are found. ( 910 ) 
     If no devices are found, the orphan device continues scanning ( 905 ), though after some period of time it may determine that there are no nearby devices and may shut down, switch channels, start a new network, or take other action as appropriate. 
     If a device is found, the orphan device will listen for a network beacon to see if it can hear the network coordinator ( 915 ) and thus determine whether a network coordinator has been found. ( 920 ) 
     If a network coordinator is found, the orphan device will request entry into the network using an association process. ( 925 ) It will wait to determine if its entry is approved ( 930 ), and if so, will enter the network ( 935 ). Once in the network, it will be able to request communication with the identified device through the network coordinator. 
     If either no network controller is found ( 920 ) or entry into the network is not approved ( 930 ), the orphan device will determine that either it cannot hear the network coordinator or the network coordinator cannot hear it. The orphan device will then listen for probe commands from the identified network device that use an immediate-acknowledgement policy ( 940 ), continually determining whether any such probe commands are heard. ( 945 ) 
     If no such probe commands are heard, the orphan device continues listening ( 940 ), though after some period of time it may determine that no probe command will be forthcoming and may shut down, switch channels, start a new network, or take other action as appropriate. 
     If a probe command from the desired device with an immediate acknowledgement policy is heard, the orphan device will then acknowledge that probe command ( 950 ) to let the transmitting device know that the orphan device 
     Then the orphan device will wait for the network device to create a child network, and when the child network is created will take what steps are necessary to join the child network. ( 955 ) Since the orphan device must be able to communicate with the network device (else it never would have received the probe command, nor would the network device have received the acknowledgement), it should have no trouble associating with the child network and communication can begin. 
     In particular, a disclosed of operating an orphan device may include: scanning a wireless channel for operating network devices; listening for a network beacon on the wireless channel if the scan identifies an operating network device on the wireless channel; receiving a probe command from the operating network device; acknowledging the probe command to the operating network device if no network beacon has been received; listening for an invitation from the operating network device to join a child network; and joining the child network, 
     The probe command may be addressed to a reserved device identifier. The reserved device identifier may be an unassigned device identifier that specifically references devices that have not been assigned individual device identifiers. 
     The method may be implemented in an ultra wideband device. The method may also be implemented in an integrated circuit. 
     Operation of an Orphan Device Using an Adjacent Network 
       FIG. 10  is a flow chart of the operation of an orphan device using an adjacent network according to a disclosed embodiment of the present invention. 
     As shown in  FIG. 10 , the operation  1000  starts when the orphan device scans for nearby devices ( 1005 ) and determines whether any devices are found. ( 1010 ) 
     If no devices are found, the orphan device continues scanning ( 1005 ), though after some period of time it may determine that there are no nearby devices and may shut down, switch channels, start its own network, or take other action as appropriate. 
     If a device is found, the orphan device will listen for a network beacon to see if it can hear the network coordinator ( 1015 ) and thus determine whether a network coordinator has been found. ( 1020 ) 
     If a network coordinator is found, the orphan device will request entry into the network using an association process. ( 1025 ) It will wait to determine if its entry is approved ( 1030 ), and if so, will enter the network ( 1035 ). Once in the network, it will be able to request communication with the identified device through the network coordinator. 
     If no network controller is found, the orphan device will listen for the transmission of other network frames not sent by a network coordinator. ( 1040 ) 
     If no network traffic is found, the orphan device will consider that the identified device is an independent device, not a network device, and will process accordingly. ( 1045 ) 
     If either no network traffic is found ( 1040 ) or entry into the network is not approved ( 1030 ), the orphan device will determine that either it cannot hear the network coordinator or the network coordinator cannot hear it. The orphan device will then create its own network on an alternate channel ( 1050 ) and begin sending out a beacon with a child network desired information element  700  included that identifies the network device with which communication is desired. ( 1055 ) 
     The orphan device (now coordinator in its own network) determines whether a new network has been formed adjacent to it, e.g., by performing a channel scan. ( 1060 ) If no new network has been formed devices are found, the orphan device continues scanning for new networks ( 1060 ), though after some period of time it may determine that there are no nearby devices and may shut down, switch channels, change its power level, or take other action as appropriate. 
     If, however, it discovers that a child network has been created, it will end its adjacent network, and take what steps are necessary to join the child network. ( 1065 ) Since the orphan device must be able to communicate with the network device (else it never would have received the probe command, nor would the network device have received the acknowledgement), it should have no trouble associating with the child network and communication can begin. 
     In particular, a disclosed method of operating an orphan device may include: scanning a wireless channel for operating network devices; listening for an operating network beacon on the wireless channel if the scan identifies an operating network device on the wireless channel; creating a local network with the orphan device as a local network controller, if the orphan device does not hear an operating network beacon; sending a local network beacon including a request to create a child network; listening for an invitation from the operating network device to join a child network; and ending the local network and joining the child network if an invitation to join the child network is received from the operating network device. 
     The local network beacon may include an operating device identifier for the operating network device. The local network beacon may also include a plurality of operating device identifiers for a plurality of operating network devices identified by the orphan device as operating on the wireless channel. The local network beacon may also include a child network identifier for the child network. 
     The method may be implemented in an ultra wideband device. The method may also be implemented in an integrated circuit. 
     Operation of a Device in a First Network Scanning an Adjacent Network 
       FIG. 11  is a flow chart of the operation of a network device in a first network scanning an adjacent network according to a disclosed embodiment of the present invention. 
     As shown in  FIG. 11 , the operation  1100  begins when the network device performs a remote scan to scan available channels for the presence of other networks ( 1110 ) and determines whether any network beacons have been found (indicating the presence of an adjacent network) ( 1120 ) 
     If the scan discovers no beacons, the network device will assume that there are no adjacent networks and will continue with normal processing until it is time to perform the next channel scan ( 1130 ), at which time the network will repeat the channel scan. ( 1110 ) The frequency of the channel scan can vary as needed by the network. Greater frequency will cost more in overhead, but will adjacent networks to be identified sooner, while lower frequency will cost less in overhead, but will increase the chance that networks created by orphan devices will remain undiscovered for longer periods of time. 
     If a beacon is found, however, the network device will determine if the beacon contains a child network desired information element indicating that the coordinator of the adjacent network wishes to request that the network device form a child network. ( 1140 ) 
     If the network device does not find a child network desired information element in the beacon identifying it by device identifier, it will assume that the coordinator of the adjacent network does not wish it to create a child network and will continue with normal processing until it is time to perform the next channel scan ( 1130 ), at which time the network will repeat the channel scan. ( 1110 ) 
     If, however, the network device does not find a child network desired information element in the beacon identifying it by device identifier, it will know that there is an adjacent orphan device (currently serving as the coordinator of the adjacent network) that desires to communicate with it. The network device can then request the network controller to allow it to create a child network. ( 1150 ) 
     Then the network device must determine if its request is approved. ( 1160 ) If the request is not approved, the network device will continue with normal processing until it is time to perform the next channel scan ( 1130 ), at which time the network will repeat the channel scan. ( 1110 ) 
     If the request is approved, the network device will create a child network and allow new devices to associate. ( 1170 ) Since the orphan device must be able to communicate with the network device (else it never would have identified the network device sufficiently to identify it by device identifier in the child network desired information element, nor would the network device have received the beacon containing the child network desired information element), it should have no trouble associating with the child network and communication can begin. 
     CONCLUSION 
     This disclosure is intended to explain how to fashion and use various embodiments in accordance with the invention rather than to limit the true, intended, and fair scope and spirit thereof. The foregoing description is not intended to be exhaustive or to limit the invention to the precise form disclosed. Modifications or variations are possible in light of the above teachings. The embodiment(s) was chosen and described to provide the best illustration of the principles of the invention and its practical application, and to enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims, as may be amended during the pendency of this application for patent, and all equivalents thereof, when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled. The various circuits described above can be implemented in discrete circuits or integrated circuits, as desired by implementation.