Supporting emergency calls on a wireless local area network

Support emergency calls on wireless LAN

This creation is generally about a wireless local area network (hereinafter referred to as WLANs), and this creation is especially about supporting emergency calls on a WLAN.

Existing 802 technologies (802.11WLANs, 802.15 wireless personal area networks (WPANs), etc.) traditionally do not support emergency calls like cells. For the cell, emergency call support is usually due to technically imposed adjustment requirements, and therefore it is widely used in most of todays subordinate wireless cell networks and<img file="TWM288740U_D0001.tif" />Support system. Emergency calls involve aspects across all communication layers, especially signal support and hosting procedures, which do not exist in 802.11 and 802.15 technologies.

With the creation of Internet telephony on WLAN, and the daily increase in the usage of WLANs, it is necessary to support emergency calls in WLAN.

Even the "fixed" Internet phone service provided to the home market restricts emergency call support, and the number address information cannot always be tracked by the dispatcher in a public security response point, that is, the call cannot always be returned, and Location registration may be required when purchasing a device. When the VoIP phone is moved to another new location, the emergency call will still be sent based on the registered address information. The registered address can be changed in principle, but updating the information in the PSAP will delay at least a few days from the beginning of the application Or a few weeks. In addition, some users may not be used to updating their registration information in a timely manner.

This situation will worsen when VoIP phones using WLANs are more mobile. WLAN-based VoIP phones can operate in any location, and users can be expected to roam seamlessly between locations, such as from the office to the home to a public hospital and so on.

Some 802.11 specifications include wireless access, access point (hereinafter referred to as AP) location, cell location, and emergency call. Regarding wireless access, emergency calls do not have any priority in the existing 802.11 standards, and no device can recognize emergency calls and general calls in the WLAN access network. There is currently no patented method that allows the network to know the location of an AP or STA, even if, for example, AP identification can be easily determined. There is currently no patented method to survey the location of the caller.

Regarding permission, if the caller is not authorized to enter the network, a tightly managed WLAN can prevent the emergency caller from establishing an emergency call. The normal connection procedure between the STA and the AP requires the STA to send a related request. Before the STA connects to the AP, the AP must negotiate with it. If the STA cannot instruct it<img file="TWM288740U_D0002.tif" />When establishing an emergency call, it is necessary to go through the entire connection procedure to determine whether the emergency call is allowed to be established. The difficulty of this form is that, for example, if an STA does not have the appropriate password or authorization certificate to access the system, (if the AP is set to require a password or authorization certificate, for example, a private Hotspot or corporate/company WLAN), the AP will directly reject the STA connection request, but even if the STA has the appropriate password or authorization certificate, the AP can still refuse to enter the network, which is based on its set voice The maximum capacity of the user. In this case, the correct decision of the AP will be to approve the emergency call (with higher priority), and refer to other existing voice call services, because the current AP lacks the device to make a decision at the first place Such features cannot be implemented by existing conventional WLAN technology. The operation of a cellular system will be in contrast to this, in which an emergency call can be established on any device, even a device without a SIM card.

This creation proposes different system operation modes to enable emergency call processing to support 802.11 and 802.15 technologies. Some of the suggestions are about new L2 signal messages or information elements to instruct emergency calls to APs. New procedures and control mechanisms are planned for emergency situations. In addition, dual modes (WLAN and second-generation (2G) ) The implementation of the third-generation (hereinafter referred to as 3G)) program is also described here. Because the emergency call requirements are usually related to the control requirements of the location report of the emergency callers location, devices and signal procedures are also proposed to allow the request and report of the geographic location in a WLAN network. The location information can be combined with the emergency call Together, they can also be executed separately.

The advantage of an STA that can recognize an emergency call is that simple logic can be installed in the AP to allow the AP to recognize the STA that should be treated normally (that is, according to the normal connection procedure), and should be allowed under any circumstances STA, regardless of network settings (that is, to offload any secure request to allow an emergency call).

A device capable of identifying emergency calls in a wireless local area network includes an indicator for identifying a unique emergency call. The indicator can be a one-bit flag or an information element.

A device for reporting the location information of a base station in a wireless local area network, which includes a location information range.

A LAN configured to support emergency calls. It includes a base station and an access point (AP). The base station includes a transmitter/receiver, an antenna connected to the transmitter/receiver, and an antenna connected to the transmitter/receiver. The emergency call identification device of the transmitter/receiver, a location device connected to the transmitter/receiver, and a waiting time determination device connected to the transmitter/receiver. The AP includes a transmitter/receiver, an antenna connected to the transmitter/receiver, an emergency call identification device connected to the transmitter/receiver, and a location device connected to the transmitter/receiver , And a waiting time signal device connected to the transmitter/receiver.

Hereafter, the dedicated term "base station" (hereinafter referred to as STA), which includes but is not limited to a wireless transmission/reception unit, a user equipment, a fixed or mobile subscriber unit, a pager, or a wireless environment Any type of device used in the When referring to the dedicated term "access point" (AP) hereinafter, it includes but is not limited to a base station, a node B, a site controller, or any form of interface device in a wireless environment.

This creation is applicable to all WLANs, personal area networks (hereinafter referred to as PANs) and metropolitan area networks (hereinafter referred to as MANs), but especially applicable to 802.11-based WLANs, 802.15-based wireless PANs, Wireless MANs based on 802.16/20, and equivalent equipment. It must be understood that this authoring system is suitable for implementing WTRUs that include WLAN, PAN, MAN and other access technology combinations, as well as WTRUs where the cellular is a multi-mode.

The original creation used to deal with emergency support will be described in three main parts below. However, this is only for explanatory purposes and should not be regarded as a limitation of this creation.

1. Air interface related signals/support and procedures

A. In the MAC frame and the MAC signal message, the emergency call indication. Figure 1 shows a standard MAC frame 100. The MAC frame 100 includes a frame control range 102 and a duration/ID range 103 One or more address ranges 106a to 106d, a sequence control range 108, a quality of service (hereinafter referred to as QoS) control range 110, a frame body 112, and a frame check sequence (hereinafter referred to as FCS) range 114. The QoS control range 110 is divided into a plurality of sub-ranges, as shown in the figure.

The priority of the emergency call is determined by the bit flag in the MAC frame, the emergency message format IE, the part of the emergency message on the existing or new IE, or the reservation used in any existing IE or MAC frame. The (currently unused) value is indicated by the executed emergency call code. This indicator allows the AP to know that it must allow the emergency call. For the same purpose, the QoS priority or request is indicated by the QoS category (for example, DiffServ), and any existing MAC frame form (control, management or Data) can be modified to include the emergency call indicator. The emergency call indicator can be added to the MAC frame, header, or any position in the body using any mechanism described.

As shown in FIG. 2A, a MAC frame 200 includes ranges 202 to 214, which are the same as those described above with reference to FIG. 1 and 102 to 114. In one embodiment, a simple bit flag 220 is used to indicate to the receiver that the received call is an emergency call. As shown in Figure 2A, the possible position of the bit flag 220 is a reserved bit (bit 7) of the QoS control range 210. Those who are familiar with this technique should note that the bit flag 220 can be placed in MAC frame, any current reserved position of any existing header or frame body range. As shown in FIG. 2B, a MAC frame 250 includes a frame control range 252, a length range 254, and an emergency call IE 256 to indicate an emergency call. The emergency call IE 256 can include, but is not limited to, an emergency call flag 260, a reason code range 262, a performance information range 264, a location information range 266, a speech encoder application range 268, and an additional range 270 . The emergency call IE 256 can be added to any MAC frame. In addition, the information contained in the emergency call IE 256 can also be added to an existing IE format.

The emergency call flag 260 can be a simple indicator (for example, a one-bit flag) to indicate that the call is an emergency call. The reason code range 262 indicates the reason for the emergency call (for example, fire, medical emergency, etc.). The performance information range 264 includes the ability of the STA to place the emergency call, and is used to help complete the emergency call as soon as possible. The location information range 266 includes the location where the STA places the emergency call. The voice encoder application range 268 identifies the voice encoder used by the STA, and if there is any incompatibility between the STA and the AP, it is used to process the emergency call. Additional information may be included in the emergency call IE (ie, range 270), which is a time stamp and WTRU and/or operator service performance information.

The existing MAC frames under 802.11 have call priority. The transmission specification (hereinafter referred to as TSPEC) IE includes a three-bit priority sub-range within the transmission standard information range. The principle of this creation can also be applied to the TSPEC IE It is executed in the middle, which is by defining an emergency call value. In the cellular system, a similar mechanism (a signal frame) is used to send the call parameters to the network, and includes a reserved range to identify the emergency call.

B. Location information

The location information can also be attached to these new MAC frames 200, 250 (for example, in the location message range 266), in addition to conveying the emergency call establishment reason. For example, from the AP or STA that performs basic service combination (hereinafter referred to as BSS) ID, AP or STA MAC address, static or dynamic allocation of IP address, or global positioning system (hereinafter referred to as GPS) information function, AP or STA can use these functions and send these messages to the emergency call center. It is worth noting that the location information can also be transported separately from the emergency call information.

Other devices for locating the emergency STA include, but are not limited to, identifying the STA by the caller ID to place the emergency call, using a response number, and using a known address by the emergency call center to help Locate the STA, (for example, use the MAC address attached to the current point of the STA, such as AP, or network ID, or AP geographic coordinates).

For example, the MAC signal mechanism of a WLAN can be used for the location of the AP that can be requested by a STA, and the STA will report its location to the AP. A possible implementation includes assisted GPS (A-GPS) coordinates, which are currently It is widely used in honeycomb handheld systems. Multiple positioning methods can be used to support different access networks, which include, but are not limited to, the time difference of arrival on the chain (U-TDOA), enhanced observation time difference (E-TOD), and the off-chain observation time difference of the idle period of arrival ( IPDL-OTDOA), A-GPS, global geographic coordinates (for example, as defined in IEEE standard 802.11k or IETF RFC 3825), and methods of using WLAN AP location, cell battle station, or segment information, and Time course or round-trip time measurement. Although the previous method used to transport location information has been specifically described, those skilled in the art will understand that any format for transporting geographic coordinates can be used.

The emergency call function can be performed separately (or complementarily) with the location report function. To illustrate, it is possible: (1) when the STA does place an emergency call, add location information to the emergency call signal frame; and (2) the signal location update is regarded as an independent operation function and does not include an emergency call. The latter will keep the AP periodically (for example, every few seconds) to notify and update the latest STA location, that is, take turns to query as part of the AP background operation, or use the STA to actively provide a standard location report. AP. Maintaining the location information of the AP will be applauded, because when the STA makes an emergency call, the AP already has a reasonable STA location prediction, so that the STA does not need to explicitly transport its location to the emergency call request.

For example, the position information of an independent STA can be used to allow the execution of a location service within a WLAN network, which is similar to an address control request.

As far as it is concerned, the location information can also be provided to the location service (hereinafter referred to as LCS) application that exists in the interactive WLAN (I-WLAN), the open land mobile network (PLMN), or the STA (hereinafter referred to as LCS). , Service call identification or service AP identification originating from the party can also be provided to LCS customers.

C. Extend the existing RTS/CTS frame switching mechanism and procedures

A standard RTS frame 300 is shown in Figure 3. The RTS frame 300 includes a frame control range 302, a duration range 304, a receiver address (hereinafter referred to as RA) range 306, a transmitter address (hereinafter referred to as TA) range 308, and an FCS range 310 .

An STA that wants to transmit an emergency call will transmit an extended RTS frame 400, which includes a special signal flag as shown in Figure 4A, or an extended RTS frame 450, which includes as shown in Figure 4B Show a new IE.

FIG. 4A shows an RTS frame 400. The ranges 402 to 410 of the RTS frame 400 are the same as the ranges 302 to 310 of the RTS frame 300 described above with reference to FIG. 3. The frame control range 402 has several sub-ranges, including a protocol version sub-range 412, a form sub-range 414, a sub-form sub-range 416, a transmission to distribution system (hereinafter referred to as DS) sub-range 418, and a DS sub-range Range 420, a more paragraph sub-range 422, a retry sub-range 424, a power management sub-range 426, a more data sub-range 428, a wired equivalent privacy (WEP) sub-range 430, and an ordered sub-range Range 432.

The signal flag can be added to any reserved bit of the RTS frame 400. The possible positions of the reserved bits include the protocol sub-range 412, the format sub-range 414, and the sub-format sub-range 416. It is worth noting that those who are familiar with this technique can place the signal flag on any position of the RTS frame 400.

4B shows an extended RTS frame 450, including a frame control range 452, a duration range 454, an RA range 450, a TA range 458, a destination IE 460, and an FCS range 462. The destination IE 460 may be similar to the emergency call IE 256 described above. All STAs receiving the extended RTS frame 450 then request to stop any transmission within a predetermined time, so as to free the wireless medium and give the STA in the emergency state a transmission opportunity.

In one embodiment, according to the received extended RTS frame, the receiving STAs enter a modified waiting time procedure in order to give the STA placing the emergency call a higher probability to successfully gain access to the media. There are two ways to modify the waiting time program: (1) briefly place the waiting time of the STA for the emergency call relative to other STAs, or (2) lengthen the waiting time of the non-emergency STAs. Regardless of the implementation, the final result is that the emergency STA has a shorter waiting time than other non-emergency STAs.

Figure 5 illustrates a method of using the RTS frame 400 or 500; the purpose of the method 500 is to make the transmission medium idle so that an STA can transmit an emergency call. In the method, an STA places an emergency call by sending an RTS frame 400 or 450 (step 502); an AP receives the RTS frame (step 504) and responds to the STA with a standard CTS frame (step 502). 506); Determine the backoff type used by the AP (step 508). There are two types of wait time that enable the STA to place the emergency call to access the media that has priority over all other STAs waiting to be transmitted.

If the waiting time type indicates that the emergency STA (that is, the STA placing the emergency call) has a shorter waiting time, the emergency STA then waits for the reduced waiting time (step 510) and then transmits the emergency call (step 512). All other STAs trying to access the media wait for the standard waiting time (step 514), and then can transmit (step 516); then the method is terminated (step 518).

If the waiting time type indicates that all other STAs have a longer waiting time (step 508), the emergency STA waits for the standard waiting time (step 520), and transmits the emergency call (step 522); all the other STAs Wait for a longer waiting time (step 524), and then transfer can be performed (step<img file="TWM288740U_D0003.tif" />6); Then the method is terminated (step 518).

Generally speaking, when an STA enters a waiting time procedure, the STA will try to transmit randomly at a time slot outside the sequence of N time slots; when the transmission conflicts, the STA will wait again and increase the value of N to A predetermined maximum value. Before an STA can try to transmit, the STA must wait for M time slots. This basic procedure allows any STA to have an equal opportunity to access the media. In order to implement QoS, there are two ways in 802.11e to confirm that a particular station has a greater chance of gaining access to the media; the first is to reduce the value of M to give the STA a shorter waiting time; second One is to use a smaller value of N, which increases the chance that a STA can transmit in a specific time slot.

In the method 500, there are several ways to let a STA know which waiting time value will be used; the first way is to use the hard-coded values of M and N related to an emergency call, so an emergency call The STA will use these hard-coded values of M and N; the second method is to use the clear signal values of M and N from the AP to the emergency STA. Generally, the AP will use a dedicated management frame during broadcast or normal system operation. Send these parameters to the STA. If STAs need to set up an emergency call, the STAs will read the emergency call-related configuration parameters to be used; for example, as part of the beacon or probe, the AP responds to the management frame and other The BSS configuration value of is sent to all STAs in its BSS, and the M and N parameters related to the emergency call are naturally expanded to the above situation; for example, each access field used by all STAs in the BSS ( Waiting time value, window... etc.) 802.11e QoS related configuration parameters are currently sent by APs using the same mechanism.

The third method is a combination of the above-mentioned first and second methods, so that a STA has its normal M and N hard-coded default values, and when the STA is in an emergency state, the AP will send a message New M and N values are generated to cancel the hard-coded default values. Those familiar with this technical field can imagine other ways to communicate the appropriate waiting time to an emergency STA and all other STAs seeking to access the media.

D. Commissioned conversion of dual-mode WLAN STAs to another radio technology (such as 3G and WLAN)

In an emergency state, the dual-mode WLAN STA will first try any emergency call on the cellular network instead of the emergency call on the WLAN; it is mainly a hard-coded procedure in the STA alone. Figure 6 illustrates the method 600 for executing this procedure.

The method 600 starts with the user making an emergency call at the STA (step 602), and then determines whether the STA can operate on a cellular network or a WLAN (step 604); if the STA is in a Operate on the cellular network (that is, connect to the cellular network at the time), the STA maintains the emergency call on the cellular network (step 606); if the STA can operate on the cellular network but If it is not connected to the cellular network immediately, the STA establishes a connection with the cellular network (step 608), and generates an emergency call on the cellular network (step 606); if the STA is operating in a WLAN , The STA will switch to the cellular network to generate the emergency call (step<img file="TWM288740U_D0004.tif" />0)。

After the emergency call is placed, it is determined whether the emergency call passes through the cellular network (step 612); if "Yes", the method is terminated (step 614); and if the emergency call does not pass through the cellular network If it is a network, the STA switches to the WLAN to make a call (step 616), and then terminates the method (step 614).

If an emergency call needs to be issued by a dual-mode WLAN-cellular mobile phone, the better procedure is to withdraw the mobile phone to the cellular modulator-demodulator (that is, a cellular radio link). This is because the emergency call supported on the WLAN may not be valid or may be less reliable.

An alternative example of the method 600 includes (1) when trying to send an emergency call, establishing a better delegated handover or suggested handover command of a radio technology (such as WLAN or cellular network); (2) the system operator Configure the emergency call performance on the SIM card of the dual-mode mobile phone or a similar device; (3) When an emergency occurs, maintain a VoIP call on the cellular network or move the call to a traditional circuit switch Audio channel; (4) The system operator sends a better radio technology local command on the wireless interface; or (5) The user configures the policy setting manually.

E. Bridging authentication and security when trying an emergency call

One of the prescribed procedures is that any 802.xx STA seeking to establish an emergency call in a WLAN must be approved by the AP, which includes the authentication that the crossover direction is 802.1x and other security methods on the network side; this The process can be started by using the extended RTS/CTS method 500 (as shown in Figure 5), or by bit flag, IE, header, prepared information fields, Or the bit/sequence value in the MAC frame (as shown in Figure 2A and 2B).

II. WTRU performance/procedures in emergency

A. WLAN sends SOS beacon signals to help find callers

A procedure appointed in the STA or configured by the network is that once the emergency call ends (or even during an emergency call), the STA and/or the AP involved will start to transmit SOS-type signals at regular intervals The frame 700 is shown in Figure 7.

The SOS signal frame 700 is a modified version of the probe request frame. The SOS signal frame 700 includes a frame control field 702, a duration field 704, a target address (DA) field 706, A source address (SA) field 708, a BSSID (basic service group ID) field 710, a serial control field 712, an SSID (basic service ID) IE 714, a support rate IE 716, and an emergency call IE 718, where the emergency call IE 718 can be the same as the emergency call IE 256 shown in Figure 2 above; and it should be noted that the support rate IE 716 is not necessary, it can be removed from the SOS signal frame 700 Without affecting its function.

In a specific embodiment, the SOS signal frame can be defined as a probe with short interframe space (SIFS) priority or with priority interframe space (PIFS) priority Request a frame to confirm access to the media. The SOS signal frame includes new emergency call related components in the emergency call IE, such as 911 ID (caller ID), detailed equipment (such as International Mobile Equipment Identification (hereinafter referred to as IMEI)), network contact, and use The name of the person and the emergency reason code, where the reason code can be obtained by a device that prompts the user to identify the reason for the emergency call (for example: "press 1 in a fire emergency"... etc.). The reason code makes it possible to handle emergency situations when the call in progress cannot be terminated.

The SOS signal frame can be scheduled to be transmitted every 100 mSec, or it can help to record or track the location. The AP can be required to record any SOS signal frame reception with timestamp and signal details. The signal strength details include signal strength, signal quality, antenna position and gain, such as IMEI, user name (if available) Such as caller details, as well as other 802.11 device information that helps to identify and effect, and at the same time request that the AP receiving an SOS signal frame must report the event to the emergency response radio resource allocation, location, and tracking the call One of the emergency network nodes of the device.

The SOS signal frame sent and received by the emergency worker approaching the caller is an active detection mechanism, and a similar application is the emergency beacon in the black box of an airplane. In response to this idea, we can introduce a<img file="TWM288740U_D0005.tif" />To realize this idea, the MAC frame of the MAC frame, or the expansion of an existing MAC frame by new IEs (for example, the emergency call IE 256).

A method of using an SOS signal frame is shown in Figure 8. The user makes an emergency call from an STA (step 802). The STA starts to transmit the SOS box (step 804). According to the desired execution, the SOS box can be transmitted as a probe or used to establish a direct connection with an emergency worker (step 806).

If the SOS frame is transmitted like a probe, the transmission period has been set and a decision will be made regardless of whether the end of the transmission has been reached (step 810). If the transmission period has not ended, the STA will continue to transmit the SOS frame (step 812) and the method will return to step (step 810). If the end of the transmission period has been reached (step 810), the STA will stop transmitting the SOS frame (step 814) and the method will terminate (step 816).

If the SOS box is used to establish a direct connection with an emergency worker (step 806), a decision will be made regardless of whether the emergency worker is within the range of the STA (step 820). If the emergency worker is not within the range of the STA, the STA will continue to transmit SOS frames and establish a direct connection between the caller and the emergency worker (step 824), and terminate the method (step 816) ).

In a first alternative (steps 810-814), once the emergency call ends, the SOS frame transmitted by the STA can be transmitted from the AP or higher level protocol, such as the Session Initiation Protocol (hereinafter referred to as SIP) Triggered by sending a signal. The duration/frequency of the SOS frame is included in this trigger signal. Sending the SOS box after the emergency call ends can avoid the transmission of unnecessary SOS boxes, especially when the emergency call is wrong, or when an emergency worker responds to the call. When not needed.

In the second alternative (steps 820-824), a direct VoIP connection between the emergency worker and the caller has been established, especially when they are not within each other's range. Other STAs that hear this SOS box can regard the SOS box as an extended RTS box as described in Figure 4 (A), (B), and Figure 5 (meaning other STAs). There will be no need to try to access the medium, which allows the emergency caller to have better access bandwidth).

B. The network (for example, AP) performs a call reply function to handle these emergency calls.

Once an emergency call is established, even after the emergency call has ended in the case of re-calling, the WLAN will still maintain an active connection for the user who initiated the emergency call for a period of time. This function may be obvious to the user.

Functionality on the infrastructure

A. Proxy function

A method 900 for determining whether an AP needs to operate as a proxy of an STA is shown in FIG. 9. The STA makes an emergency call (step 902) and the AP receives the emergency call (step 904). Regardless of whether the STA has the ability to complete the emergency call, a decision will be based on the utilization to complete the call<img file="TWM288740U_D0006.tif" />Made over the Internet (step 906). The AP checks whether the STA has all the desired functions (for example: SIP/H.323 protocol terminal, voice changer, etc.) to support the call. This information may be indicated as part of the MAC box (for example: MAC box 200, 250) or it may be part of the client information in the network accessible by the AP.

If the STA has all the required functions, the STA will execute the call in a normal procedure (step 908). If necessary, the AP can add location information to the call, including the location of the STA and/or the location of the AP (for example, the network ID, the MAC of the AP, etc.) (step 910). The method then terminates (step 912).

If the STA does not have all the required capabilities to complete the call (step 906), the AP operates as a proxy of the STA to provide any necessary functions (step 914). The AP adds the location information to the call as a necessary function (step 910), and then the method terminates (step 912).

If the AP terminates that the STA does not have all the required functions to complete the emergency call under the current environment, the AP will operate as a proxy for the STA (step 914). For example, if the STA does not have SIP protocol support, the AP can operate as a SIP proxy for the STA. In another embodiment, if the STA has SIP support but the network only supports H.323, the AP can interact with SIP information from the STA to H.323 information to other networks. In an extreme example, the STA does not even have a voice-changing effector. The AP can download a thin voice-changing effector to the STA and interact with more standard voice-changing effectors elsewhere on the network.

Another method is the AP spoofing (that is, reading the content and/or information even if it is not officially believed to be true) the content of the IP packet that is used for signaling or is normally trafficked by the STA and its status The counterpart on the Internet. For example, SIP signaling protocol information on IP is currently customarily used for call processing. Such SIP signal transmission contains useful information, such as the AP capability information and the destination address, in order to realize its proxy role. In addition to the aforementioned methods, if the AP extracts such information from the higher-layer (that is, above the L2 MAC) information content of the remote destination address of the STA, it can act more efficiently. Its role. Those familiar with the art will recognize that SIP is an embodiment of a management protocol for IP-based calls, and other equivalent protocols also exist and are widely used in this industry. Therefore, this method is not limited to SIP only.

B. Connect an AP to an emergency call center

Once an AP learns that an STA makes an emergency call, the AP needs to establish a connection to an emergency call center in order to properly route the call from the STA. There are several possible delivery mechanisms to obtain emergency calls from the AP to the call center. For example, the AP can communicate with an entrance gateway to connect to the call center.

<img file="TWM288740U_D0007.tif" />The concept of emergency network nodes can be extended to include an emergency response operation center with man-in-the-loop capabilities. The emergency network node can be an extended service group (ESS) or a network tailored to infrastructure applications. For example, on a university campus, the designated emergency network node may be the police department on the campus. In another embodiment, in a manufacturing plant, the emergency network node may be a security office. The emergency network node may include an operator for receiving VoIP calls, long-call messages, screen calls, and a public switched telephone network (hereinafter referred to as PSTN) that will place an emergency call later. To alert the appropriate authorities.

The emergency network node concept can be further extended to include an automated node with a direct line to a PSTN. The automated node can operate as a voice circuit bridge to dial and connect wireless callers to the PSTN emergency center.

The described method for connecting to the emergency call node can be extended to include the ability to specify a call route and process the call without the need for certification, authorization, or security features. This will allow a direct, unencrypted link or link under a channel between the wireless caller and the emergency network node.

The functions of the emergency network node can be extended to include call processing, call handover, and roaming control. This functionality will pre-authorize resources in neighboring APs (other APs adjacent to the AP used for wireless calls), which has enabled the caller to proceed without losing the wireless connection and without having to re-establish a new emergency call. Roaming, especially when moving across AP borders, reduces repeated calls to the same emergency phone.

IV. A WLAN setup to support emergency calls

A WLAN 1000 setting to support the emergency call is shown in Figure 10. The WLAN 1000 includes a STA 1002 and an AP 1004. The STA 1002 includes a transmitter/receiver 1010 that communicates via a connected antenna 1012. An emergency call identification device 1014 is connected to the transmitter/receiver 1010 and is configured to send an emergency call located at the STA 1002 (meaning that the call is identified as an emergency call). A location device 1016 is connected to the transmitter/receiver 1010 and is configured to provide location information from the STA 1002 to the AP 1004. A waiting time determining device 1018 is connected to the transmitter/receiver 1010 and is configured to determine how long the STA 1002 needs to wait after transmitting an RTS frame when making an emergency call.

The AP 1004 includes a transmitter/receiver 1020 that has been connected to an antenna 1022 for communication. An emergency call identification device 1024 is connected to the transmitter/receiver 1024 and is configured to identify incoming emergency calls. A location determining device 1026 is connected to the transmitter/receiver 1024 and configured to determine the location of the STA 1002. A waiting time sending device 1028 is connected to the transmitter/receiver 1024 and is configured to send a notification telling the STA 1002 how long it needs to wait for a response before continuing to transmit an emergency call.

The concept of this creation can be extended beyond the specific specific embodiments described above. For example, this creation can be extended to mesh networks and special networks. In an alternative example, in addition to a human user, this creation can be extended to use WLANs to urgently handle machine-to-machine usage scenarios. One possibility would be to use 802.11 in the home security system, which means a WLAN is used to replace the telephone line (the line that can be cut off) for hardware wiring. In this embodiment, when someone breaks into the security system, there is no need for a human user to make a WLAN emergency call, and the home security system automatically generates an emergency call to a secure call center. In another alternative, the home security system may start to transmit an emergency SOS box and operate as described above.

Although the elements and features of this creation are described in detail in the foregoing specific embodiments, especially their combined specific embodiments, each feature or element may also be alone (meaning that other elements of these preferred embodiments are not included). Or features) or any changes with or without other features or elements of this creation.

<p>100, 200, 250MAC frame</p><p>300, 400, 450RTS standard frame</p><p>500, 600, 800, 900Method</p><p>700SOS signal frame</p><p>114, 214, 310, 410, 462Frame check sequence</p><p>270Extra Range</p><p>306, 406, 456receiver address</p><p>308, 408, 458Transmitter address</p><p>430Wired equivalent privacy</p><p>418, 420distribution system</p><p>706Target address</p><p>708Source address</p><p>710Basic Service Group ID</p><p>714Basic Service ID</p><p>WLANWireless Local Area Network</p><p>Platform 1002</p><p>1004Access point</p><p>1012,1022antenna</p><p>1000,1010,1020Transmitter/Receiver</p>

Fig. 1 is a standard media access control (MAC) block diagram; Fig. 2A is a MAC block diagram with a one-bit flag to indicate an emergency call; Fig. 2B is a block diagram with a message Component (IE) is used to indicate an emergency call MAC signal block diagram; Figure 3 is a standard ready to send (RTS) signal block diagram; Figure 4A is a one-bit flag to indicate an emergency call RTS signal block diagram; Fig. 4B is an RTS signal block diagram with an information element (IE) to indicate an emergency call; Fig. 5 is a RTS signal diagram using the RTS shown in Fig. 4A or Fig. 4B Fig. 6 is a flow chart of a method for switching wireless technology to complete an emergency call; Fig. 7 is a block diagram of an SOS beacon indicating an emergency call; Fig. 8 is A flow chart of a method for transmission using the SOS frame as shown in Figure 7; Figure 9 is a flow chart of a method for determining whether to use an agent function; Figure 10 is a WLAN configured to support emergency calls picture.