GB2542826A

GB2542826A - Wireless access point

Info

Publication number: GB2542826A
Application number: GB1517313.1A
Authority: GB
Inventors: Brown Ruth; Gomez Alistair
Original assignee: British Telecommunications PLC
Current assignee: British Telecommunications PLC
Priority date: 2015-09-30
Filing date: 2015-09-30
Publication date: 2017-04-05
Also published as: GB201517313D0

Abstract

A method of operating a wireless network access point to control access of at least one mobile device to a voice service accessible via the wireless access point, the wireless access point having a wireless network interface for communication with the at least one mobile device via a wireless link and a wide area network interface for communication with a wide area network. The wireless access point monitors the status of the network link between itself and the wide area network via the wide area network interface. If the monitored network link is determined to be disrupted the wireless access point terminates the wireless link to the at least one mobile device and rejects requests by the at least one mobile device to re-establish the wireless link so that the at least one mobile device loses access to the voice service. The mobile device may be configured to access a Voice over WIFI (VoWIFI) service via the wireless access point and further access a Voice over LTE (VoLTE) service via a separate communication link that does not transverse the wireless access point. The mobile device may handover from VoWIFI to VoLTE in response to termination of the wireless link.

Description

Wireless access point

Field of Invention

The present invention relates to managing wireless communication services and in particular to a method and apparatus for controlling WLAN and cellular service access.

Background

Cellular data networks provide data connectivity to mobile devices having cellular network interfaces. The network is formed of a network core for handling control plane functions and data packet routing, and a radio access network (RAN) of macrocell base stations located throughout the coverage area of the mobile network for wireless communication with subscriber mobile devices. An example of a cellular network architecture is Long Term Evolution (LTE). Unlike previous generation second generation (2G) and third generation (3G) cellular networks which offer packet switched data services on top of a circuit switched voice platform, LTE is an all-packet switched data network architecture that does not support the traditional voice calling platform.

Since LTE does not support traditional voice telephony, some mobile network operators provide traditional voice telephone services by making the mobile device switch from the LTE network to a 2G/3G service for the duration of a telephone call or when a short messaging service (SMS) is received. This process is known as Circuit Switched Fall-Back (CSFB). CSFB provides a reliable way of handling voice calls but requires the network operator to maintain both the LTE and legacy networks, the former for data connectivity and the latter for voice telephony and slow data access where the LTE network coverage is lacking.

Wireless local area networks (WLANs) operating in accordance with the IEEE 802.11 family of standards (commonly referred to as WiFi ™) are common in many user locations and provide data connectivity over a short geographic range. Typically the wireless local area network is generated and maintained by a wireless access point which acts as a packet routing interface between devices connected to the WLAN (e.g. smartphones, tablets) and local devices connected via a wired interface (televisions, network attached storage). The wireless access point serves local devices and will typically be co-located, or integrated with an external network interface such as a modem for providing a backhaul link to external networks such as the Internet via an Internet Service Provider's core network. Example backhaul technologies include Digital Subscriber Line (xDSL) copper/fibre and cable based on the Data over Cable Service Interface Specifications (DOCSIS) architecture.

Such a combined WLAN, routing and modem device will be referred to as a hub throughout the description.

Both LTE and WLANs are examples of packet switched data networks in which application data is split into packets and the packets can take any path within the network to arrive at the receiver. In contrast the circuit switched networks require a dedicated data path to be established prior to sending data along the dedicated circuit.

VolP/VoLTE/VoWiFi

Voice over Internet Protocol (VoIP) applications are known for allowing voice communication via a packet switched network. The voice data is sampled into packets of voice data and the packets are sent over the data network. Although the packets may arrive in a different order to the transmission order, packet loss is tolerated because latency has a greater negative effect on the quality of experience to the users. VOIP applications are Over-The Top (OTT) services which typically require a user to generate a username identity and generally a VoIP call can only be established between two users having the same VoIP application on their mobile devices. Even where the VoIP application allows calls to conventional telephones and the caller information display shows the caller's telephone number, when the callee tries to return the call, the call goes to the standard dialler and not the VoIP application.

Furthermore, in the VoIP service it is not possible to maintain a call if the mobile device moves out of range of the current access point and requires a handover from one access technology to another.

Voice over LTE (VoLTE) is a voice service running over LTE uses optimised headers and priority marking to provide a voice service using the packet switched network with an aim to reducing/replacing the reliance on CSFB and VoIP. This will reduce operating overheads and may allow parts of the legacy 2G and 3G platforms to be switched off.

Due to the prevalence of WLANs in many areas, the Voice over WiFi (VoWiFi) or WiFi Calling service has also been deployed by several network operators. In VoWiFi, the WLAN is regarded as a non-3GPP access network base station to the LTE network so that voice calls are made and received using the standard telephony software and packet data is tunnelled to and from the cellular network core. VoWiFi therefore appear to extend the cellular network coverage to indoor locations and allows handover to a normal VoLTE or CSFB service when the mobile device moves to an outdoor location.

Mobile devices such as smartphones will therefore have both a cellular network interface and a WLAN interface for data connectivity. Traditionally WLANs offer faster, more reliable and unmetered service so the mobile device is configured to prefer the WLAN interface for all data connectivity when both WLAN and cellular access is available.

With the conventional processing, the mobile device is only concerned with the quality of the WLAN signal to the hub. As long as the WLAN signal strength is above a signal strength threshold, the mobile device will stay connected to the WLAN even if there is no onward connection the external networks such as the Internet. This can cause confusion for users because the phone displays a strong WLAN connection (typically via an icon with various bars to indicate signal strength) but the data services do not connect.

The present invention addresses the above problems.

Statements of Invention

In one aspect, an embodiment of the present invention provides a method of operating a wireless network access point to control access of at least one mobile device to a voice service accessible via the wireless access point, the wireless access point having a wireless network interface for communication with the at least one mobile device via a wireless link and a wide area network interface for communication with a wide area network, the method comprising: monitoring the status of a network link between the wireless access point and the wide area network via the wide area network interface; and if the monitored network link is determined to be disrupted: terminating the wireless link to the at least one mobile device; and rejecting requests by the at least one mobile device to re-establish the wireless link so that the at least one mobile device loses access to the voice service.

In a further aspect, an embodiment of the present invention provides a wireless network access point for controlling access of at least one mobile device to a voice service accessible via the wireless access point, comprising: a wireless network interface for communication with the at least one mobile device via a wireless link; a wide area network interface for communication with a wide area network; and means for monitoring the status of a network link between the wireless access point and the wide area network via the wide area network interface; wherein if the monitored network link is determined to be disrupted, the wireless network interface is configured to: terminate the wireless link to the at least one mobile device; and reject requests by the at least one mobile device to re-establish the wireless link so that the at least one mobile device loses access to the voice service.

Figures

Embodiments of the present invention will now be described with the aid of the accompanying Figures in which:

Figure 1 schematically shows an overview of a telecommunications network of the first embodiment;

Figure 2 schematically shows the behaviour of a hub and UE in the telecommunications network when a network link is disrupted;

Figure 3 schematically shows the internal components of a hub in accordance with the first embodiment;

Figure 4 schematically shows the internal components of a user entity device in accordance with the first embodiment;

Figure 5 is a flowchart showing the operation of the hub to identify VoWiFi capable UEs;

Figure 6 is a flowchart showing the operation of the hub to cause UEs to switch from VoWiFi to VoLTE; and

Figure 7 is a flowchart showing the operation of the hub to cause UEs to reconnect to VoWiFi from VoLTE.

Description

System overview

Figure 1 shows an overview of the main components in a telecommunications communication system 1 according to the first embodiment. The system 1 has several functional subsystems: a Long Term Evolution (LTE) cellular network 3 infrastructure; non-cellular network infrastructure 5 including a local network and Internet Service Provider (ISP) architecture; and an IP Multimedia Subsystem (IMS) 7.

The LTE cellular network 3 provides cellular network client devices, known as User Entities (UE) such as mobile telephones 9 with data and voice services using a packet-switched IP network in contrast to the older circuit switched networks. The LTE cellular network includes a network core 11 and a radio access network formed of eNodeBs 13 for connecting services and resources in the network core 11 to the UEs 9. The network core 11 contains the standard control functions such as a Multimedia Mobility Entity (MME) (not shown), a Home Subscriber Server (HSS) (not shown), and a Policy Configuration Rules Function (PCRF) (not shown). For routing data packets to remote resources, there are a number of Serving Gateways (SGW) (not shown) and Packet Gateways (PGW) (not shown).

The IMS 5 is an IP data network which provides a unified service architecture for all networks. Multiple services can be provided on a single control/service layer even though the access networks may be different. The IMS 7 therefore reduces the need for duplication in data services/applications. The VoLTE and VoWiFi voice calling services are hosted in an application server 15 within the IMS 7 which in this embodiment is provided by a service known as the Multimedia Telephony Service (MMTel).

The non-cellular network infrastructure 5 includes a wireless access point/modem router device 17, hereinafter referred to as a hub, located in the home generating a wireless local area network (WLAN) 19 in accordance with the IEEE 802.11 family of standards to allow communication with UEs 9 and also WLAN only devices such as a computer 10. For external network access, the hub 17 communicates with an Internet Service Provider (ISP) 21 which routes data via a wide area network such as the Internet 23 to external servers and users.

Due to the ability of the LTE cellular network 3 to use non-cellular access for applications such as WiFi-Offload, the LTE cellular network 3 also includes an Evolved Packet Data Gateway (ePDG) 25 which acts as a termination point for IPSec tunnels with the UE over non-trusted 3GPP IP systems. This allows data into the EPC network core 11 for processing within the LTE cellular 3 and IMS 5 networks.

The UE 9 has both WLAN and LTE radio interfaces for accessing the non-cellular network infrastructure and the LTE cellular network respectively and the UE 9 supports VoLTE, WoWiFi and CSFB voice calls. To highlight the difference between UEs 9 and other connected WLAN devices 10, the computer 10 only has a WLAN interface and therefore can only access the WLAN 19 of the hub 17 but not the cellular network 3 since it does not have an interface capable of sending and receiving LTE signals.

Behaviour of UE for activating WiFi and LTE interfaces

As mentioned above, the UE 9 has both WLAN and LTE interfaces and is capable of both VoLTE and VoWiFi call handling. Since an eNodeB 13 of the LTE network has a larger geographical coverage range than a WLAN 19, in general the UE will be connected to the LTE network 3 and will use VoLTE.

However, when the UE is within range of a WLAN 19 such as shown in Figure 1, there is overlap in the connectivity ranges, and the UE 9 could connect to data services using either the cellular interface or the WLAN interface. In general, the default policy is that a WLAN connection is preferred. So a UE connected to the LTE network and it detects a known WLAN, the UE will try to use the WLAN.

Therefore upon detection of a known WLAN, the UE 9 will enable its WLAN interface and disable the cellular interface causing any existing services to also be disconnected. This change is generally transparent to the user of the UE as it has little impact to the operation of services such as file transfers and web browsing. However, the general UE policy of preferring WLANs to cellular data interfaces can have an impact on the Quality of Experience for users of voice services using VoWiFi instead of VoLTE.

In particular, the UE 9 connects to the WLAN 19 of the hub 17 which in turn connects to external network resources such as the MMTel service 15 in the IMS 7 and other web servers via the ISP 21. If the link to the ISP 21 is not operational, then the UE cannot communicate externally and therefore will not be able to make and receive voice calls using VoWiFi.

However, as long as the UE detects the WLAN 19, it will maintain the WLAN connection in preference to the LTE connection. Therefore even if there is no connection to the VoWiFi service, the UE 9 will remain connected to the WLAN 19 which may result in the user of the UE missing voice calls because the phone is not registered on either the VoWiFi or the VoLTE services.

In the embodiment, the hub 17 is aware that some connected devices can use VoWiFi and so the hub is configured to monitor whether the data link to the ISP service is operational. As shown in Figure 2, if the data link is down, then in order to maintain voice connectivity for VoWiFi UEs 9, the hub 17 will cause the UE 9 to handover to VoLTE despite the WLAN 19 being available. In this embodiment, the hub 17 triggers the handover by disconnecting the UE 9 from the WLAN 19 and does not respond to the UE's 9 WLAN association requests. In this way, the UE 9 is made to believe it is not in range of a WLAN and therefore it will enable the LTE network interface and register for VoLTE. The advantage of the above processing, is that no modifications are required at the UE. Only standard mechanisms in the WLAN protocol are used at the UE.

After the processing to disconnect any VoWiFi capable UEs 9, the hub is configured to continue to monitor the status of the data link to the ISP. When the connection is restored, the hub 17 will allow the UE 9 to reconnect to the WLAN 19 by responding to the WLAN association requests. Once the UE 9 has seen the availability of the WLAN 19, in accordance with the usual processing, the UE will connect to the WLAN 19 and trigger a registration to VoWiFi service and therefore handover from VoLTE to VoWiFi to use the WLAN access network.

The components of the hub will now be described with reference to Figure 3.

Figure 3 shows the internal components of the hub 17 in more detail. The hub 17 contains a number of network interfaces for communication with various types of network device. For local devices, there is a Wireless Local Area Network (WLAN) interface 31 for communication with wireless devices using a wireless protocol such as the IEEE 802.11 family of wireless LAN standards known as WiFi™. In this embodiment, the WLAN interface 31 is compliant with the 802.11ac standard for WLAN operation. For wired LAN devices there is an Ethernet interface 33 in accordance with the IEEE 802.3 standards.

For connectivity to the Internet Service Provider (ISP), the hub 17 has a Wide Area Network (WAN) interface 35 which in this embodiment is a modem compliant with the Digital Subscriber Line (xDSL) family of standards such as Very High Speed DSL (VDSL) modem. In an alternative where the ISP is based on Data Over Cable Service Interface Specification (DOCSIS), the WAN interface 35 is a cable modem compliant with the DOCSIS cable standards.

The hub 17 also contains a packet routing function 37 which is responsible for managing the flow of data packets between the three interfaces 31, 33, 35. The packet routing function 37 processes the headers of incoming packets received on the three interfaces 31, 33, 35 and determines where to send the packets for onward delivery to the intended packet destination. The packet routing function 37 will also include functions such as Network Address Translation (NAT) for directing packets between the local interfaces 31, 33 and the WAN interface 35.

To monitor the status of the link between the WAN interface 35 and the ISP 21, the hub 17 contains a VoWiFi monitor function 39. This function is connected to the WAN interface 35 and the packet routing function 37 and is responsible for determining if the link to the ISP 21 is inoperative and therefore UEs 9 would not be able to use VoWiFi and if so, to cause the UEs 9 to switch to VoLTE.

To monitor the link failure, the VoWiFi monitor function 39 contains a WAN line statistics checker 41, a directory of ePDG addresses 43 and a VoWiFi connected client list 45.

The DSL line statistics checker 41 is linked to the WAN interface 35 to extract information about the WAN interface 35 to ISP 21 link, in particular whether a link is established and active. The ePDG directory 43 contains a list of known ePDG IP addresses since they are the termination point of IP Sec tunnels with the UE 9 for allowing data to enter the cellular network core 11 and communicate with the IMS 7 services. Finally, the connected device list 45 contains the identity of any UEs 9 which are using the VoWiFi service. This is so that other WLAN devices such as computers 10 can be ignored for the processing of the hub 17 since they are not able to run a VoWiFi service.

The components of the UE 9 will now be described with reference to Figure 4.

The UE 9 contains a cellular network interface 51 and a WLAN interface 53. The cellular interface 51 is compatible with the eNodeB 13 of the cellular network 3 and the WLAN interface 53 is compatible with the WLAN interface 31 of the hub 17.

Since either interface 51, 53, may be used by the UE 9, a data link interface 55 is responsible for enabling and disabling each interface 51, 53 as required and for routing user data and control packets to the interfaces 51, 53.

An operating system 57 in responsible for the overall operational tasks performed by the UE 9 and links a number of applications and services 59 to the data layer interface 55. One of the applications within the applications and services 59 is a telephony application 61 which is compatible with VoLTE and VoWiFi.

In normal operation, the telephony application 61 is configured to connect to the MMTel service 15 provided in the IMS 7 to provide voice services via VoLTE and VoWiFi. The UE 9 registers for VoWiFi when it is connected to a WLAN 19 and the UE registers for VoLTE when it is connected to the LTE cellular network 3.

The operation of the hub 17 to handle connected VoWiFi capable UEs 9 will now be described.

Since there is a distinction between UEs 9 and other WLAN devices 10, the hub periodically runs a process to determine which devices on the WLAN 19 are VoWiFi capable. Whilst any WLAN capable device 9, 10 can connect to the hub 17 provided it has the relevant credentials, not every device will be VoWiFi capable. For example, certain smart phones are enabled for VoWiFi, but older smartphone hardware, laptops and computers will not be capable of supporting VoWiFi and therefore will not benefit from the processing of the first embodiment. It is therefore important for the hub 17 to identify a set of UEs from the total population of connected UEs.

Figure 5 is a flowchart showing the scan process. In this embodiment, the hub 17 makes a passive determination of whether the device is VoWiFi capable by analysing the address information of data packets sent between UEs and external resources.

In step si, the VoWiFi monitor39 retrieves a list of known ePDG addresses from the ePDG directory. The ePDGs are gateways to link Non-Trusted Non-3GPP networks to network operator EPCs and IMS services. The addresses of the ePDGs are publically known and therefore can be provided by the ISP 21 to the hubs 17 via a management service such as TR-069 or similar method for ISP 21 to hub 17 communication.

In step s3, the VoWiFi monitor 39 identifies VoWiFi capable UEs 9 from the total set of connected WLAN devices by analysing the IP Flows traversing the hub 17. In particular any IP Flows which have an ePDG gateway address as destination can be assumed to be an IP flow for VoWiFi traffic between a VoWiFi capable UE 9 and the MMTel voice service 15. If any such flows are present, in step s5 the VoWiFi monitor 39 extracts the device information such as MAC address and current IP address of the UE 9 forming the local end of the identified IP Flows and in step s7, the VoWiFi monitor 39 stores the identified UEs 9 in the connected client list 45 ready for subsequent processing during normal operation. The MAC address, allocated IP address and identity of the ePDG are stored so that the hub knows which subset of WLAN devices 9, 10 are VoWiFi capable.

Monitoring IP flows relies on the standard processing of a UE 9 which is capable of VoWiFi service to establish the IPSec tunnel to the ePDG 25 as soon as it connects to the WLAN 19 in order to register and/or handover to VoWiFi from VoLTE. Therefore devices which do not establish a connection to an ePDG are considered to be standard WLAN devices.

The scanning process is periodically performed by the VoWiFi monitor 39 to maintain the validity of the connected client list 45 so that any new devices 9, 10 that connect to the WLAN 19 are identified. In this embodiment, the scan is performed every 5 minutes.

Once the connected client list 45 contains information for at least one VoWiFi capable UE 9, then the VoWiFi monitor 39 will begin monitoring the WAN link state.

Since the hub 17 contains a WAN interface 35, the VoWiFi monitor 39 has access to the WAN line statistics and operational state of the WAN interface 35. The operation of the VoWiFi monitor will be described with reference to Figure 6.

In step sll, the WAN link state and statistics are retrieved from the WAN interface 35 and in step sl3, a test is made to check whether the WAN connection to the ISP 21 network is operational. If the WAN link is active and online, then in step sl5, the line statistics checker 41 will wait a predetermined amount of time, in this case 5 seconds, before looping back to step sll to reevaluate the WAN link state.

If in step sl3 the test determines that the WAN link is disconnected, then in step sl7 the list of VoWiFi capable devices in the connect client list 45 is retrieved and in step sl9 the VoWiFi monitor 39 causes those identified UEs 9 to disconnect from the WLAN 19 of the hub 17 by sending a WLAN disconnect instruction and refusing to respond to UE probe requests. This causes the standard processing of the UEs to behave as if they are not in range of the WLAN 19 and therefore they will connect to the LTE cellular network 3 and register to VoLTE so that there is no service disruption.

Since the processing of Figure 6 only affects VoWiFi capable UEs 9, any other WLAN devices 10 continue to be connected to the WLAN so that they can communicate with other WLAN resources although access to external devices will still be disrupted until the link to the ISP and external resources is re-established. WAN link re-established

Having disconnected the VoWiFi capable UEs 9 so that they can register for VoLTE, it is still desirable to reconnect these UEs 9 to the WLAN as soon as possible because the user of the UE may not realise that they are using their cellular data link and data allowance instead of being on a WLAN.

The hub is therefore arranged to monitor the WAN link state and using the standard behaviour of the UEs 9, cause the UEs 9 to reconnect to the WLAN 19 when the link is regarded to be stable.

Figure 7 is a flowchart of the operation of the hub in this embodiment.

In step s21, the WAN line statistics function 41 checks the WAN interface 35 and once the WAN link information has been retrieved, in step s23 a check is performed to determine if the WAN link has been re-established. If the WAN link has not been re-established then processing returns to step s21 after a time delay, in this case two minutes.

If the WAN link is determined to be active, then in step s25 the WAN link statistics checker 41 monitor the link for a period of time to ensure that the link is stable. The period of time is set to provide a balance between responsiveness and ensuring a degree of certainty that the WAN link really is stable and in this case it is five minutes.

After the stability testing period has elapsed, then in step s27 a determination is made as to whether the link is stable. If the link active but not considered to be stable, then processing returns to step s25 and the link is monitored for another stability test period.

Alternatively, if the link is considered to be stable, then in step s29 the VoWiFi monitor 39 will configure the WLAN interface 31 to respond to WLAN probe and association requests from the VoWiFi capable UEs in the connected device list 45 and processing ends.

As explained previously, the standard UE 9 behaviour is to connect to a WLAN 19 in preference to the cellular LTE network 3. Therefore even when a UE is connected to a cellular network 3, it will continue to send WLAN probe requests for known WLANs 19. So when the hub 17 starts responding to the UE's probe requests, the UE 9 will recognise that a known WLAN 17 is available and therefore associate and authenticate onto the WLAN 17. Once connected, then the UE will handover from VoLTE to VoWiFi.

The processing of the hub 17 allows a UE or set of UEs connection to VoWiFi and VoLTE via a WLAN or a cellular network respectively to be controlled so that the UE can continue to receive voice service even when the link between the hub and ISP is disrupted.

Claims

1. A method of operating a wireless network access point to control access of at least one mobile device to a voice service accessible via the wireless access point, the wireless access point having a wireless network interface for communication with the at least one mobile device via a wireless link and a wide area network interface for communication with a wide area network, the method comprising: monitoring the status of a network link between the wireless access point and the wide area network via the wide area network interface; and if the monitored network link is determined to be disrupted: terminating the wireless link to the at least one mobile device; and rejecting requests by the at least one mobile device to re-establish the wireless link so that the at least one mobile device loses access to the voice service.

2. A method according to claim 1, wherein the at least one mobile device is configured to access a Voice over WiFi (VoWiFi) voice service via the wireless access point and further configured to access a Voice over LTE voice service via a separate communication link which does not traverse the wireless access point, wherein, in response to the termination of the wireless link, the mobile device performs a handover process from VoWiFi to VoLTE.

3. A method according to any preceding claim, wherein after the wireless link is terminated, if the monitor network link is determined to be operational, the wireless access point reestablishes the wireless link to the at least one mobile device.

4. A method according to claim 2 or 3 further comprising identifying the at least one mobile device which is configured to access the VoWiFi service by analysing IP data flows to a gateway server of at least one cellular communications network.

5. A wireless network access point for controlling access of at least one mobile device to a voice service accessible via the wireless access point, comprising: a wireless network interface for communication with the at least one mobile device via a wireless link; a wide area network interface for communication with a wide area network; and means for monitoring the status of a network link between the wireless access point and the wide area network via the wide area network interface; wherein if the monitored network link is determined to be disrupted, the wireless network interface is configured to: terminate the wireless link to the at least one mobile device; and reject requests by the at least one mobile device to re-establish the wireless link so that the at least one mobile device loses access to the voice service.

6. A wireless access point according to claim 5, wherein the at least one mobile device is configured to access a Voice over WiFi (VoWiFi) voice service via the wireless access point and further configured to access a Voice over LTE (VoLTE) voice service via a separate communication link which does not traverse the wireless access point, wherein, in response to the termination of the wireless link, the mobile device performs a handover process from VoWiFi to VoLTE.

7. A wireless access point according to claim 5 or 6, wherein after the wireless link is terminated, if the monitoring means determines that the network link is operational, the wireless network interface re-establishes the wireless link to the at least one mobile device.

8. A wireless access point according to any of claims 5 to7 further comprising means for identifying the at least one mobile device which is configured to access the VoWiFi service by analysing IP data flows to a gateway server of at least one cellular communications network.

9. A computer program containing processor executable instructions for causing a processor to carry out the method of claims 1 to 4.