Pre-notification of potential connection loss in a wireless local area network

Notify in advance that the connection in the wireless LAN may be lost

BACKGROUND OF THE INVENTION As a means of avoiding the cost and inconvenience problems associated with wired network connections, wireless local area networks (WLAN) are becoming more and more popular. In a typical WLAN solution, one or more wireless access points (AP) are connected to a wired local area network (LAN) to provide one or more user equipment with wireless access to the wired LAN (although there are other WLAN configurations). Once a wireless link is established between the user equipment and the AP, the user equipment is generally basically able to operate in the same manner as in the case of having a wired connection to the network. User equipment connected to the network through a wireless link obtains a certain degree of mobility, which is not possible in a fully wired network. That is, to a certain extent, the user equipment can be carried by the user (for example, from the user's office to a nearby conference room, etc.) without losing the connection to the network. However, if the user leaves the corresponding AP too far, the network connection will be lost. If this happens, any open applications on the user device that are using the network connection may crash, which may result in the loss of data and/or other valuable information.

Brief Description of the Drawings Fig. 1 is a block diagram illustrating the topology of a wireless local area network (WLAN) according to an embodiment of the present invention; Fig. 2 is a block diagram illustrating a user notification device used with wireless user equipment according to the present invention; A block diagram of a wireless LAN configuration according to an embodiment of the invention; FIG. 4 is a block diagram illustrating a wireless LAN configuration according to another embodiment of the present invention; and FIG. 5 is a flow chart illustrating a method for notifying a user that a wireless network connection may be lost according to an embodiment of the present invention Figure.

Detailed Description In the following detailed description, reference is made to the accompanying drawings, which illustrate specific embodiments in which the present invention can be implemented. These examples are described in sufficient detail to allow those skilled in the art to implement the present invention. It should be understood that although the various embodiments of the present invention are different, they are not necessarily mutually exclusive. For example, a specific function, structure, or characteristic described in this specification in conjunction with one embodiment can be implemented in another embodiment without departing from the spirit and scope of the present invention. In addition, it should be understood that the position or arrangement of the units in each disclosed embodiment can be modified without departing from the scope and spirit of the present invention. Therefore, the following detailed description should not be understood in a restrictive sense, and the scope of the present invention is limited only by the appended claims and all equivalents of the claims with proper interpretation of the claims. In all the drawings, the same numbers refer to the same or similar functions.

FIG. 1 is a block diagram illustrating a wireless local area network (WLAN) topology 10 according to an embodiment of the present invention. Other network topologies can also be used. As shown in the figure, the wireless access point 14 provides access to the wired LAN 12 for one or more user equipment 16, 18, and 20. Although not shown, one or more additional access points may be connected to the wired LAN 12 to provide wireless access to additional user equipment. The wired LAN 12 may include, for example, one or more servers to provide client/server functions within the network 10. The wired LAN 12 may also include a function for providing a connection to another network (for example, the Internet, a wide area network (WAN), etc.). User equipment 16, 18, 20 may include any of a variety of different digital data processing equipment, including, for example, laptop computers, palmtop computers, and/or desktop computers; personal digital assistants (PDAs); pagers; and/ Or other. The number of user equipment that an access point 14 can support may vary from system to system.

The user equipment 16, 18, and 20 each include a wireless transceiver function that can establish and maintain a wireless communication link with the corresponding access point 14. The wireless transceiver function generally conforms to one or more wireless networking standards or technologies. Some common wireless networking standards/technologies include, for example: IEEE 802.11a, IEEE 802.11b, IEEE 802.11g, HomeRF, HiperLAN, Ultrawideband, Bluetooth, Wireless Asynchronous Transfer Mode (WATM), Digital Enhanced Cordless Communication (DECT) , Wireless Universal Serial Bus (USB), wireless IEEE1394, etc. The one or more user equipment 16, 18, 20 may include a wireless network interface card (NIC) (e.g., 802.11b NIC, etc.), which is installed in an appropriate input/output port of the device. Similarly, one or more user equipment 16, 18, 20 may also include wireless network components directly integrated in the equipment (that is, without using a plug-in card or board). Generally, the user equipment is also equipped with an antenna or other transmitting equipment or converters. In one implementation scheme, radio frequency (RF) energy is used to implement wireless communication between each user equipment and the corresponding access point. However, it should be understood that other forms of wireless signals (such as infrared signals, etc.) may also be used.

The range in which the wireless access point 14 can support reliable communication with the user equipment is generally limited. Therefore, when the user equipment is far away from the access point 14 (for example, when the user takes his/her laptop to participate in a meeting), it may eventually reach a certain point where the network connection is lost. At this time, any application programs (for example, email programs, Internet browsers, etc.) that are running on the user's device (or on a remote server) using the network connection may crash. Such a crash may result in the loss of valuable information and/or work results, and additional work may be required to return the corresponding user device to a running and usable state (for example, the Microsoft Windows® operating system may require the user to press control- alt-delete key combination to close the unresponsive program). It can be determined that if the corresponding user is notified of the potential connection loss problem before the connection loss actually occurs, many potential problems related to the loss of the wireless network connection can be avoided. This notification mechanism allows users to take corresponding protective measures when the possibility of connection loss continues to increase.

FIG. 2 is a block diagram illustrating a user notification device 22 used with wireless user equipment according to the present invention. As shown in the figure, the user notification device 22 includes a connection loss possibility monitor 24 and an enunciator 26. The connection loss possibility monitor 24 is used to determine whether the possibility that the user equipment will lose the wireless network connection increases. When the connection loss possibility monitor 24 detects such a situation, the notifier 26 is used to notify the relevant user of the user equipment so that the user can take corresponding measures. The notifier 26 may include any form of device that can provide this notification to the user, such as a visual device, an audio device, and/or an audio/visual device. Multiple notifiers 26 can also be used. In one method, both the connection loss possibility monitor 24 and the notifier 26 can be set together with the corresponding user equipment. For example, both the connection loss possibility monitor 24 and the notifier 26 may be part of a network interface card installed in the user equipment. Alternatively, both the connection loss possibility monitor 24 and the notifier 26 may be directly integrated into the user equipment. In another alternative, one of these two functions can be part of the NIC, while the other function is directly integrated into the device. The notifier 26 may also be externally connected to the user equipment (for example, as an external display and/or speaker). Multiple notifiers 26 can also be provided, which are either part of the NIC respectively, or are directly integrated into the user equipment or connected to the user equipment from the outside. Of course, other configurations are also possible. In another method, the connection loss possibility monitor 24 is provided in a remote location (for example, in a network access point), and the notifier 26 is provided on the user equipment.

In at least one embodiment, the connection loss possibility monitor 24 determines whether the connection is lost based on input information related to the wireless channel supporting the network connection. For example, in one method, the connection loss probability monitor 24 receives information related to one or more signal levels related to the wireless channel (e.g., the received signal level in the user equipment and/or the access point). If the signal level is below the threshold, the monitor 24 can determine that the possibility of a lost network connection is increasing. In another method, the connection loss probability monitor 24 receives information about the rate of change of the signal level related to the wireless channel (or the monitor 24 can calculate the rate information based on the aforementioned signal level information). If the signal level drops at a rate above the predetermined rate, the connection loss possibility monitor 24 may determine that the possibility of wireless network connection loss has increased. In another possible method, the connection loss probability monitor 24 receives bit error rate information related to the wireless channel (for example, the received bit error rate of the user equipment or the access point). If the bit error rate is higher than the predetermined threshold, the connection loss possibility monitor 24 may determine that the possibility of wireless network connection loss is increased. Of course, other technologies and combinations of technologies for determining connection loss can also be used.

As described above, the notifier 26 is used to notify the user that the network connection may be lost before the connection loss occurs, so that the user can take appropriate measures. Therefore, the notifier 26 may include any form of device that can notify the user, such as a visual device, an audio device, or both of these devices. For example, the notifier 26 may include an indicator provided on the outer surface of the user equipment, a user display associated with the user equipment, a speaker associated with the user equipment, and the like. Of course, a combination of such structures can also be used.

Fig. 3 is a block diagram illustrating a wireless LAN configuration 28 according to an embodiment of the present invention. As shown in the figure, the wireless LAN configuration 28 includes a wireless access point 30, at least one user equipment 32, and a wired LAN 40. The wireless access point 30 provides the user equipment 32 with access to the wired LAN 40 (or another network structure). The user equipment 32 communicates with the wireless access point 30 through the wireless communication channel 36. The wireless access point 30 includes an antenna 42, a transceiver 44, a signal strength monitor 46 and a controller 48. The user equipment 32 includes: a wireless NIC 34, a host 38, a display 58 and a speaker 60. The wireless NIC 34 includes an antenna 50, a transceiver 52, an indicator 54 and a controller 56. The wireless NIC 34 can be detachably connected to an input/output (I/O) port (for example, an expansion slot or a PCMCIA slot) of the host 38. Or, wireless NIC The functions of 34 can be integrated into the user device 32 (ie, implemented within the device 32 rather than as a plug-in card or board). It should be understood that the blocks shown in FIG. 3 (and other block diagrams) are functional and do not necessarily represent separate hardware units. For example, in at least one embodiment, two or more functional blocks (or parts of them) are used in general-purpose digital processing equipment (such as general-purpose microprocessors, digital signal processors (DSP), reduced instruction set computers (RISC) ), Complex Instruction Set Computer (CISC), Field Programmable Gate Array (FPGA), Application Specific Integrated Circuit (ASIC) or others) are implemented in software. It is also possible to separate each function and implement it on multiple digital processing devices.

The transceiver 52 in the NIC 34 is used to perform conventional RF receiver and transmitter functions for the user equipment 32. That is, during the transmission operation, the transceiver 52 converts the baseband information from the controller 56 into an RF transmission signal for transmission to the wireless channel 36 through the antenna 50. During reception, the transceiver 52 will process the RF signal received from the wireless channel 36 via the antenna 50 and extract baseband information therefrom. Although shown as one unit, the transceiver 52 can be implemented with separate transmitter and receiver units. An appropriate duplexer function may also be provided to allow the transmitting and receiving functions to share a common antenna 50. In an alternative method, separate receiving and transmitting antennas are provided in the wireless NIC 34. The transceiver 44 in the wireless access point 30 is similar in function to the transceiver 52 of the NIC 34 described above. In at least one embodiment, the transceiver 44 includes multiple independent transmit/receive antennas to support simultaneous wireless communication with multiple remote user equipment. Multiple signal strength monitors 46 may be set in the access point 30 to monitor the received signal strength of multiple remote user equipment at the same time. In a system that uses infrared (IR) signals instead of RF signals, the above-mentioned antennas 42 and 50 can be replaced with a suitable converter structure.

In addition to providing other functions, the controller 56 in the NIC 34 also provides an interface between the transceiver 52 and the host 38. As described in more detail below, the controller 56 also serves as a connection loss possibility monitor to notify the user of the user device 32 when the network connection may be lost (although a separate controller can also be provided to implement this function). The indicator 54 is installed outside the wireless NIC 34 to provide the user with a visual and controllable indication of the current status of the wireless channel 36. In addition to providing other functions, the controller 48 in the wireless access point 30 also provides an interface between the transceiver 44 and the host 40. The signal strength monitor 46 is used to monitor the signal strength received by the access point 30 from the user equipment 32 through the wireless channel 36. The signal strength monitor 46 transmits the obtained signal strength information (or part of it) to the controller 48, which uses the information to generate one or more signal strength messages for transmission to the user equipment 32 (for example, through the wireless channel 36) . The controller 56 in the user device 32 can then use the corresponding signal strength information to determine whether the device 32 should be notified that the user connection may be lost.

In one method, the controller 48 in the access point 30 automatically transmits the signal strength message to the user equipment 32 (e.g., at regular intervals). In another method, the controller 56 in the NIC 34 sends a signal strength request message to the access point 30 when the signal strength information is needed, and the controller 48 in the access point 30 responds to this by responding to the signal strength. The message is sent to the user device 32. The controller 56 may transmit a signal strength request message to the access point 30 at regular intervals, so as to obtain continuously updated signal strength information. For example, in one implementation, the controller 56 causes the signal strength request message to be transmitted to the access point 30 every 100-300 milliseconds.

After the controller 56 obtains the signal strength information from the access point 30, it can use the information to generate a corresponding indication on the (optional) indicator 54. The user associated with the user equipment 32 can then view the indicator 54 when the network connection is in use to determine the current status and/or reliability of the connection. Then, if the indicator 54 indicates that the danger of connection loss is imminent, the user can take corresponding measures. In one implementation, the indicator 54 includes three light-emitting diodes (LEDs) with different colors, such as green, yellow, and red. If the signal strength information received from the access point 30 indicates that the signal strength is within the expected range for supporting the wireless link (for example, greater than or equal to 70% of the nominal power), the controller 56 may make the first one in the indicator 54 The LED emits light (for example, a green LED). If the signal strength information indicates that the signal strength is in a lower range (for example, between 40% and 70% of the nominal power), the controller 56 may cause the second LED to emit light (for example, a yellow LED). If the signal strength information indicates that the signal strength is in a lower range (for example, less than or equal to 40% of the nominal power), the controller 56 may cause the third LED to emit light (for example, a red LED). If the yellow LED is on, it informs the user that the possibility of network connection loss increases, and protective measures may need to be taken. If the red LED is on, it informs the user that the connection may have been lost, but if it has not really happened, measures should be taken immediately to prevent the connection from being lost. In another implementation solution, the indicator 54 includes only one LED, and the LED will light up as long as the signal strength is determined to be below the threshold. In another implementation, the indicator 54 includes a string of LEDs (for example, 10 adjacent LEDs), which form a signal level meter. That is, the number of LEDs that emit light at a certain time is proportional to the latest signal strength indication received by the controller 56. Similarly, an electromechanical structure meter (such as a d'Arsenval-type meter, etc.) can also be used. It is understood that many other indicator types can also be used in accordance with the present invention.

In addition to using indicator 54 (or as an alternative), NIC 34 can also use a display 58 associated with the host 38 to provide the user with notifications that the network connection may be lost. For example, in one method, when it is determined that an increasing possibility of connection loss exists (for example, when the signal strength is found to be within a predetermined range), the controller 56 transmits an alarm message to the display 58. The controller 56 utilizes, for example, an application programming interface (API) of the operating system of the host 38 to generate appropriate alarm messages. The warning message can be a simple screen warning: the current network connection is unreliable. The warning message can also include suggestions to suggest that the user save the work of all applications currently using the network connection and close them. Alternatively, more complex warning messages can be provided. For example, in one method, when the possibility of loss of connection is detected to increase, the controller 56 causes a list of possible response options to be displayed to the user on the display 58 (for example, in a dialog box). The list can include, for example, any one or more of the following response options: (1) Save all the work of one or more currently open applications and close them; (2) Save the applications of one or more currently open applications Save the program state in the cache; (3) Start a search to find an alternative access point that can support network connections for the user equipment; (4) Change the location of the user equipment to a location closer to the corresponding access point; and ( 5) Close the warning dialog without taking any measures. To ensure that the user is aware of the list, the list can be displayed in front of all other applications on the display 58, and the list can only be eliminated by the user's appropriate response. For those skilled in the art, it is obvious that other forms of warning messages can also be used.

If the signal strength information received from the access point 30 indicates that a weak signal is being received (eg, less than or equal to 40% of the nominal power), the controller 56 can be programmed to automatically take protective measures. For example, the controller 56 may automatically save the application state of some or all related applications into the cache. It is also possible to display an appropriate message to the user on the display 58.

The controller 56 can also use the speaker 60 associated with the host 38 to notify the user that the network connection may be lost. For example, in one method, the NIC 34 causes audible sound to be emitted from the speaker 60 when it is determined that the signal strength is within a predetermined range. Alternatively, a computer-generated or digitized voice message may be sent out from the speaker 60. For example, a voice message may say, for example, "You are in danger of losing network connection, please take corresponding measures." In one embodiment, the user is provided with an audible response option through the speaker 60. Then, the user can use input devices, such as a keyboard, touch screen, mouse, microphone (if voice recognition function is available), and/or other methods to select appropriate response options. In addition to or alternative to the visual notification provided by the display 58 and/or indicator 54, an audible notification may be provided by the speaker 60. For example, when the user is close to the user device 32 but is not monitoring the display 58 or indicator 54 (for example, when the user is carrying the user device to see a meeting, etc.), the audible indication can be very useful.

As described above, in at least one embodiment of the present invention, the controller 56 in the NIC 34 receives signal strength information from the wireless access point 30, and uses the information to determine whether to notify the user equipment 32 that the user's network connection may be lost. In an alternative method, the determination as to whether to provide a notification to the user is made within the wireless access point 30 instead of on the user device 32 (for example, the determination is made based on the output of the signal strength monitor 46). Then, if it is determined that a notification needs to be provided, the wireless access point 30 issues an instruction to the user equipment 32 to provide the notification. The controller 56 within the NIC 34 can then use one or more of the aforementioned techniques to provide notifications to the user.

FIG. 4 is a block diagram illustrating a wireless LAN configuration 70 according to another embodiment of the present invention. As mentioned above, the wireless access point 72 provides at least one user equipment 74 with access to the wired LAN 40 (or a similar network structure). The user equipment 74 includes: a wireless NIC 76, a host 38, a display 58 and a speaker 60. The wireless LAN configuration 70 of FIG. 4 is similar to the configuration 28 of FIG. 3, except that the signal strength monitor 46 has been moved into the NIC 76 of the user equipment 74. The signal strength monitor 46 monitors the strength of the signal received from the wireless access point 72 via the wireless channel 36. The signal strength monitor 46 transmits the signal strength information to the controller 56, and the controller 56 uses the information to determine whether it is necessary to notify the user that the network connection may be lost. The notification can be performed using the indicator 54, the display 58, and/or the speaker 60 as described above. In another possible configuration, a signal strength monitor 46 is provided on both the wireless access point and the corresponding user equipment. In this way, if the signal strength detected by any monitor indicates that the network connection may be lost, the user will be notified.

In at least one embodiment, the aforementioned user notification technique is implemented in a system that also uses transmit power control to support a wireless link between a network access point and a user equipment. Power control usually involves adjusting the device's transmit power based on the signal level of the signal that the device receives from another device. Therefore, referring to FIG. 1, when the access point 14 receives a signal stronger than the required signal, the transmit power of the user equipment 16 can be reduced (for example, to save power on the user equipment 16). Similarly, when the signal received by the access point 14 is weak, the transmit power of the user equipment 16 can be increased (for example, to improve the quality of the wireless connection). Even if power control is being implemented, the network connection may still be lost. Therefore, it is advantageous that the above-mentioned user notification technique can be used in such a system.

FIG. 5 is a flowchart illustrating a method 80 for notifying a user that a wireless network connection may be lost according to an embodiment of the present invention. First, obtain the signal strength information related to the wireless communication link supporting the wireless network connection (block 82). Next, it is determined whether the signal strength indicated by the signal strength information is greater than the first threshold (block 84). If the signal strength is greater than the first threshold, a visual indication (for example, lighting a green LED or similar indicator, etc.) may be provided to the user (block 86). The method 80 may then return to block 82. If the signal strength is not greater than the first threshold, then it is next determined whether the signal strength is greater than the second threshold (block 88). The second threshold is lower than the first threshold. If the signal strength is greater than the second threshold but less than the first threshold, a corresponding visual indication (for example, lighting a yellow LED or similar indicator, etc.) may be provided to the user (block 90). An audible indication may also be provided to the user (block 92). As a supplement (or alternative), the user can also be provided with a screen warning that the connection may be lost (block 94). Any one or more of the notification techniques can be used. The screen alert may include a list of possible response options that can be handled by the user. The method 80 may then return to block 82.

If the signal strength is not greater than the second threshold, a corresponding visual indication (for example, lighting a red LED or similar indicator, etc.) may be provided to the user (block 96). The application state of one or more application programs being executed on the user equipment can then be automatically saved in the cache (block 98). It is also possible to generate a screen message on the display device to notify the user of the current status of the wireless network connection (block 100). The screen message can also notify the user that one or more application states have been saved in the cache. A screen list of possible response strategies can also be provided at this time. The method 80 may then return to block 82.

In at least one embodiment of the present invention, the signal strength information is acquired at regular intervals (for example, every 100-300 milliseconds), and the above method 80 is repeated. The user can also be given the ability to modify the update time interval according to personal needs (for example, if the user rarely moves the user equipment, the update time interval can be increased, or the notification function can be disabled). It should be understood that many modifications can be made to the method 80 shown in FIG. 5. For example, in a modification scheme, only one threshold is used. If the signal strength is below the unique threshold, the user may be notified that the connection may be lost as described above (e.g., block 90, block 92, and/or block 94). One or more automatic response operations may also be performed (e.g., block 98). Other modifications to method 80 are also possible.

Although the present invention is described in conjunction with certain embodiments, it should be understood that, as those skilled in the art can easily understand, various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention. For example, the aforementioned user notification technology can also be used to provide an ad-hoc type wireless network (ie, a network in which the network connection is maintained through a user-to-user wireless link) in which the connection between user equipment may be lost. Notice. The modifications and changes are deemed to be within the scope of the present invention and the appended claims.