WO2013153746A1

WO2013153746A1 - Improved packet-based emergency connection support

Info

Publication number: WO2013153746A1
Application number: PCT/JP2013/001837
Authority: WO
Inventors: Go Fujimoto; Iskren Ianev; Yannick Lair; Thomas Delsol
Original assignee: Nec Corporation
Priority date: 2012-04-12
Filing date: 2013-03-18
Publication date: 2013-10-17
Also published as: GB2501110A; GB201206481D0

Abstract

Apparatus and methods provide improved packet-based emergency connection of a wireless terminal to a network. A wireless communication system includes a wireless terminal and a network apparatus. The wireless terminal and the network apparatus can connect to each other by means of one or more packet connections. The wireless terminal can wirelessly transmit an indicating signal, for receiving by the network apparatus. The signal indicates a threshold flag or number of packet connection(s) by which the wireless terminal can be connected to the network apparatus. The network apparatus receives the indicating signal transmitted by the wireless terminal and, depending upon the threshold flag or number, initiates deactivation of one or more current packet connections by which the network apparatus is connected to the wireless terminal so that an emergency packet signalling connection and an emergency packet media connection can be maintained between the network apparatus and the network apparatus.

Description

IMPROVED PACKET-BASED EMERGENCY CONNECTION SUPPORT

The present invention relates to emergency services provided by a wireless communications system, and in particular to ways of providing improved packet-based emergency connection.

Internet Protocol (IP) Multimedia Subsystem (IMS) emergency support via the so-called packet domain (i.e. using packet-switched data) in networks operating according to the Universal Terrestrial Radio Access Network (UTRAN) and Evolved Universal Terrestrial Radio Access Network E-UTRAN standards was defined by the well-known Third Generation Partnership Project (3GPP) international standards-setting consortium, and was introduced from Release 9 onwards (see 3GPP TS23.401, s4.3.12 and TS23.060, s5.10).
IMS emergency bearer services are provided to support IMS emergency sessions. Emergency bearer services are functionalities provided by serving public land mobile network (PLMN) when the network is configured to support emergency services. Emergency bearer services are provided to attached wireless terminals and in some cases to wireless terminals that are in limited service state.

Whether emergency bearer services are provided to wireless terminals that are in limited service state (i.e. not attached) depends on local regulation and, if the local regulation does not compel it, operator policy. Receiving emergency services in limited service state does not require a subscription. Depending on such local regulation and/or operator policy, the Mobility Management Entity (MME) (in the case of E-UTRAN) or the Serving GPRS Support Node (SGSN) (in the case of UTRAN) may allow or reject an emergency attach request transmitted by a wireless terminal which is in limited service state.

To provide emergency bearer services, the MME or SGSN are configured with MME Emergency Configuration Data or SGSN Emergency Configuration Data respectively. The MME/SGSN Emergency Configuration Data are applied to all emergency bearer services that are established by an MME or SGSN upon request by a wireless terminal. The MME or SGSN Emergency Configuration Data contain the Emergency Access Point Name (APN) which is used to derive a Packet Data Networks (PDN) gateway (GW) (for E-UTRAN) or Gateway GPRS Support Node (GGSN) (for UTRAN). The MME or SGSN Emergency Configuration Data may also contain the statically configured PDN GW or GGSN for the Emergency APN.

A wireless terminal that is in limited service state, as specified in 3GPP TS 23.122, initiates the Attach procedure by indicating that the Attach procedure is for the purposes of receiving emergency services from the network. The network, if it supports emergency services for wireless terminals in limited service state and depending on local regulation, provides emergency bearer services to the wireless terminal in limited service state, regardless of whether the wireless terminal can be authenticated, has roaming or mobility restrictions or has a valid subscription. Each wireless terminal in limited service state determines, from a broadcast indicator that it receives on a broadcast channel, that the cell in which it is located supports emergency services over E-UTRAN or UTRAN.

Attached wireless terminals however initiate a packet (PDN or PDP) connectivity procedure to receive emergency bearer services, as is summarized below.

Wireless terminals that camp normally on a cell of a public land mobile network (PLMN) are informed, by means of signalling from the network, that the network supports emergency services over E-UTRAN or UTRAN. The signalling is in the form of an Emergency Service Support indicator in the Attach procedure and the Tracking Area Update (TAU) procedure or Routing Area Update (RAU) procedure (whichever applies).

Wireless terminals that camp normally on a cell may also use the emergency Attach procedure under conditions specified in TS 24.301, for example when the MM back-off timer is running.

The wireless terminal shall set the radio resource control (RRC) establishment cause to emergency as defined in TS 36.331 when the wireless terminal requests an RRC connection in relation to an emergency session.

For successful emergency service support on the packet domain (in E-UTRAN and UTRAN) the wireless terminal needs to support at least one PDN connection (for E-UTRAN) or PDP connection (for UTRAN) for signalling and another PDN/PDP connection for emergency user media (traffic/data). That is, the wireless terminal must use two packet connections to acquire emergency service, one packet connection for signalling and another packet connection for emergency media or data.

The theoretical maximum number of simultaneous (multiple) PDN/PDP connections supported by the network and the wireless terminal is 11. This maximum number of simultaneous PDN connections is aligned with GPRS requirements, in which the maximum number of Network Layer Service Access Point Identifiers (NSAPIs) does not allow more than 11 simultaneous PDP connections.

In practice typically the network and the wireless terminal do not support this maximum number of simultaneous PDN/PDP connections. A practical maximum for simultaneous PDN connections supported by the wireless terminal may be 8 due to Data Radio Bearer (DRB) constraints (see TS36.331, s11.1). The feature of multiple PDN/PDP connections support itself is an optional feature in 3GPP (see TS23.401, s5.10).

A wireless terminal, while it is in limited service state, has no active connections. A terminal and network which together support the multi PDN/PDP connection feature would support at least two packet connections. Therefore the fact that an emergency connection requires at least two simultaneous packet (PDN/PDP) connections would not present a problem when the wireless terminal is in limited service state and the wireless terminal and network both support the multi PDN/PDP connection feature.

When a wireless terminal initiates an emergency call while in limited service state, it begins by performing an emergency attach operation first.

However, a wireless terminal that has already attached to a serving network normally has already got some active PDN/PDP connections. When such a terminal initiates/requests an emergency call connection on the packet domain, it requests an emergency PDN/PDP connection(s) as an addition to any already existing PDN/PDP connection(s). If the requested additional PDN/PDP connection(s) would cause the number of active connections to exceed a threshold (in this case the maximum number of supported simultaneous PDN/PDP connections by the wireless terminal), there is a problem.

The wireless terminal would therefore not be able to succeed with the emergency connection until one or more of the existing active PDN/PDP connections are deactivated.
Fig. 1 is an event diagram showing operations (blocks 102, 122) performed by a wireless terminal 100 and a network 120 and signals, represented by horizontal arrows 131-134, transmitted between the wireless terminal 100 and the network 120, the source and destination (wireless terminal 100 or network 120) of each signal being represented by

vertical lines

105, 125 joined to the wireless terminal 100 and network 120 respectively.

This figure illustrates the current process of establishing an emergency connection on the packet domain according to the E-UTRAN standard 3GPP TS23.401, s5.10.2.

Firstly (as represented by the input of block 102) the wireless terminal 100 is in service with one or more active PDN connection(s)/context(s).

In block 102, a user of the wireless terminal 100 requests on the packet domain an emergency call. The wireless terminal 100 initiates an emergency PDN connection if the wireless terminal's threshold (in this case maximum) number of supported simultaneous PDN connections is not reached.

Otherwise (if the maximum number of active simultaneous PDN connections supported by the wireless terminal is reached prior to the emergency call) there is a problem, as explained above, whereby the wireless terminal cannot request an emergency call on the packet domain. The E-UTRAN standard 3GPP TS23.401 does not take any account of such a scenario and the emergency call will fail in this scenario.

If/when the maximum number of supported simultaneous PDN connections is not reached, the wireless terminal initiates a PDN connectivity request 131. The Request Type parameter is set to "Emergency" - see 3GPP TS23.401, s5.10.2.

In block 122 (bounded by a dashed line), when the network 120 receives the PDN connectivity request 131, the MME of the network 120 may, depending on a current MME configuration, initiate a deactivation of a non-emergency PDN connection (TS23.401, s10.5.3) as per the requirements in TS23.401, s4.3.17.4. However, the network (in particular, the MME) does not know how many, if any, packet connection(s) are available via the wireless terminal. The network does not have information about the maximum number of simultaneous PDN connections supported by the wireless terminal. Therefore such a deactivation does not take into account the maximum number of simultaneous PDN connections that can be supported by the wireless terminal.

As indicated by arrow 132 (having a dashed line), PDN connectivity deactivation may or may not occur. As mentioned above, based on the MME configuration the MME may or may not initiate deactivation of a non-emergency PDN connection. Only if it does so will resources be freed for establishing a PDN connection for an emergency.

If (as indicated by block 122 and arrow 132) a PDN connectivity deactivation is initiated by the network, then the network 120 accepts the PDN connectivity request 131 for emergency call by sending a PDN connectivity accept message, indicated by arrow 133, which is received by the wireless terminal 100, as per 3GPP TS23.401, s5.10.2.

Finally, as indicated by arrow 134, the wireless terminal 100 transmits a PDN connectivity report message to the network according to the procedure defined in 3GPP TS23.401, s5.10.2. The message 134 serves to complete an emergency packet (PDN) connection between the wireless terminal 100 and the network 120.

It is clear from the above that, according to the current state of the art, when an emergency service is required by a user of a wireless terminal that is connected in a packet session it is by no means certain that such an emergency service will be provided by the network. This is a very undesirable and potentially unsafe situation.

United States Patent Application 20110317545 discloses a Packet Data Protocol (PDP) context handling method for a Mobile Station (MS) in which a PDP context for an emergency bearer service is provided, wherein a radio access bearer (RAB) associated with the PDP context is released by a network. The method comprises the steps of: downgrading the maximum uplink bit rate and the maximum downlink bit rate associated with the PDP context from original non-zero positive values to a zero value; sending a request signal associated with a modification of the maximum uplink bit rate and the maximum downlink bit rate; and re-establishing the RAB for the PDP context with the maximum uplink bit rate and the maximum downlink bit rate reconfigured as the original non-zero values after the request signal has been sent. That document is concerned with downgrading an existing PDN connection when an emergency connection is requested so that the emergency connection could be allocated maximum uplink and downlink bit rates. It does not address the above-described problems.

A solution might be provided by the terminal itself taking a decision to deactivate one or more active PDN connection(s) before proceeding with the emergency connection if/when the maximum number of PDN connections supported by the wireless terminal is reached.

Alternatively, another solution might be provided by the terminal taking a decision to 'locally' (i.e. implicitly) release one or more active PDN connection(s) before proceeding with the emergency connection if/when the maximum number of PDN connections supported by the wireless terminal is reached.

NPL 1: 3GPP TS 23.401 V9.0.0 (2009-03)

However, a problem with these two possible solutions is that the terminal is not the entity that is best equipped to take a decision about which active PDN connection(s) to deactivate or release whereas the network has already got the capability and tools for PDN connection(s) deactivation in similar circumstances based on PDN connections prioritisation (see TS 23.401, s5.3.3.1, step 21) which (the priority list) is not available in the wireless terminals. Also, connections deactivations and releases are normally controlled by the network.

The present invention seeks to provide for a wireless terminal, a network apparatus and associated methods having advantages over known such wireless terminals, network apparatus and methods.

In particular, the present invention seeks to address the above-described problems and limitations of existing wireless communication systems and to seeks to provide improved and more reliable packet-based emergency connection support.

According to one aspect of the invention, there is provided a wireless terminal for use in a wireless communication system comprising the wireless terminal and a network apparatus, the wireless terminal comprising: means for wirelessly connecting to the network apparatus by means of one or more packet connections; means for wirelessly transmitting, for receiving by the network apparatus, a signal providing an indication of a threshold number of packet connection(s) by which the wireless terminal can be connected to the network apparatus.

According to another aspect of the invention, there is provided a network apparatus for use in a wireless communication system comprising a wireless terminal and the network apparatus, the network apparatus comprising: means for wirelessly connecting to a wireless terminal by means of one or more packet connections; means for wirelessly receiving a signal relating to a specified wireless terminal indicating a threshold number of packet connection(s) by which the network apparatus can be connected to the specified wireless terminal; and means for, depending upon the threshold number of packet connection(s), initiating deactivation of one or more current packet connections by which the network apparatus is connected to the specified wireless terminal so that an emergency packet signalling connection and an emergency packet media connection can be maintained between the network apparatus and the wireless terminal.

The signal providing an indication of the threshold number can provide the indication by indicating (e.g. by means of a flag) that the threshold number of active connections has been reached, or alternatively or additionally can provide the indication by providing a value of the threshold number. In the latter case, the network can determine, if the indication does not explicitly indicate that the threshold number of connections has been reached, that the threshold number of connections has indeed been reached because the network knows how many active connections currently exist.

The inventive features allow for successful emergency packet connection when the wireless terminal has reached its limit of supported simultaneous packet (e.g. PDN/PDP) connections, i.e when the wireless terminal does not have enough free packet connection(s) available to provide transmission/reception of emergency signalling and emergency media.

The inventive features provide advantages over other alternative solutions briefly described above, for example the solution in which the terminal itself takes a decision and deactivates or locally releases an active non-emergency PDN connection so that an emergency connection can be established.

It is advantageous for the network to take the decision to perform deactivation of a non-emergency packet connection(s) when the wireless terminal needs a packet connection for emergency service and the wireless terminal is already connected to the network by the maximum number of simultaneous packet connections supported by the terminal.

Fig. 1 is an event diagram illustrating the current process of establishing an emergency connection on the packet domain according to the E-UTRAN standard 3GPP TS23.401, s5.10.2. Fig. 2 is another event diagram illustrating a proposed new process of establishing an emergency connection on the packet domain. Fig. 3 shows a wireless terminal and network apparatus arranged for operating according to the invention.

According to an embodiment, a new parameter is included in the PDN connectivity request message (see 3GPP TS23.401, s5.10.2). Optionally, this parameter can be indicated by a flag which may be called "maximum number of supported simultaneous PDN connections flag" (max_nsc_flag).

This flag is set to ON by the wireless terminal when the wireless terminal initiates a PDN connectivity request for emergency service and the maximum number of supported simultaneous PDN connections is reached.

Alternatively, the wireless terminal can include the flag in one or each PDN connection request (not only a PDN connection request for emergency connection) when the maximum number of supported simultaneous PDN connections is reached.

According to another embodiment, the new message parameter comprises a number or parameter which may be called "maximum number of supported simultaneous PDN connections" (max_nsc) for example. The value of this parameter would be set to the maximum number of simultaneous PDN connections supported by the wireless terminal, on each occasion when a PDN connection is requested for emergency service and the maximum number of supported simultaneous PDN connections by the terminal is reached.

Alternatively, this parameter could be set when a PDN connectivity for emergency is requested regardless whether the maximum number of supported simultaneous PDN connections is reached or not.

Another alternative is that this parameter could be set in one or each PDN connectivity request (not just a request for emergency connection) and regardless whether the maximum number of supported simultaneous PDN connections is reached or not.

The new message parameter, in each case, is included in the PDN connectivity request message transmitted by the wireless terminal.

According to an embodiment, when a flag is used as described above, the network (MME) analyzes this flag each time it receives a PDN connectivity request for emergency and the network determines whether this flag indicates that the wireless terminal has reached its simultaneous PDN connectivity support limit/maximum.

According to an embodiment, the network (MME) releases or terminates an active non-emergency PDN connection(s) based on a priority list (for example as per the bearers context prioritization list in the MME, see 3GPP TS23.401, s5.3.3.1 in step 21) so that the requested emergency PDN connection can be established.

The embodiments described above will now be further described with reference to Fig. 2.

Fig. 2 is an event diagram (similar to that shown in Fig. 1) illustrating a proposed new process of establishing an emergency connection on the packet domain. Fig. 2 and the portions of the description below illustrate proposed differences compared to the current state of the art PDN connectivity request procedure outlined in E-UTRAN in 3GPP TS23.401, s5.10.2.

The event diagram of Fig. 2 shows operations (blocks 202, 222) performed by a wireless terminal 200 and a network 220 and signals, represented by horizontal arrows 231-234, transmitted between the wireless terminal 200 and the network 220, the source and destination (wireless terminal 200 or network 220) of each signal being represented by

vertical lines

205, 225 joined to the wireless terminal and network respectively.

The proposed new process shown in Fig. 2 is in keeping with, and would require minimal modification to, the E-UTRAN standard 3GPP TS23.401, s5.10.2.

In a first stage of the new process (as represented by the input of block 202) the wireless terminal is in service with one or more active PDN connection(s)/context(s).

In block 202, a user of the wireless terminal 200 requests an emergency call on the packet domain. The wireless terminal 200 initiates an emergency PDN connection provided that the wireless terminal's threshold (in this case maximum) number of simultaneous PDN connections is not reached.

Otherwise, if the threshold number of active simultaneous PDN connections is reached prior to the emergency service request the wireless terminal operates according to various embodiments as will now be explained.

According to one embodiment the wireless terminal sets a flag parameter, which may be called the "maximum number of supported simultaneous PDN connections flag" (max_nsc_flag) parameter, to ON (a logical value which otherwise is OFF), and transmits the flag in a signal for receiving by the network, when the wireless terminal requests PDN connectivity. The wireless terminal may set the flag to ON and transmit the flag when it requests any PDN connectivity. Alternatively, the wireless terminal may set the flag to ON and transmit the flag when it requests PDN connectivity for only an emergency.

According to another embodiment, the wireless terminal indicates, via a signal it transmits (which could be the same signal as above but with different content), a quantitive value, which may be known as the "maximum number of supported simultaneous PDN connections" (max_nsc).

Alternatively, the wireless terminal could indicate the "maximum number of supported simultaneous PDN connections" (max_nsc) when the wireless terminal request a PDN connection for emergency service, regardless of whether the maximum number of supported simultaneous PDN connections is reached.

Another alternative is that this max_nsc parameter could be set (and indicated to the network by being transmitted) in one or each PDN connectivity request. Such a connectivity request may be a connectivity request for a non-emergency connection and/or a connectivity request for emergency connection.

In each case, the max_nsc parameter could be set and indicated regardless of whether the threshold number of supported simultaneous PDN connections is reached or not.

The wireless terminal initiates a PDN connectivity request 231. The Request Type parameter of the PDN connectivity request 231 is set to "Emergency" - see 3GPP TS23.401, s5.10.2.

In a preferred embodiment, either the new "maximum of supported simultaneous PDN connections flag" parameter (max_nsc_flag) or the "maximum of supported simultaneous PDN connections" (max_nsc) parameter (whichever parameter is used) is set to a value as described above and is included in the PDN connectivity request 231.

In block 222 (bounded by a dashed line), when the network 220 receives the emergency-type PDN connectivity request 231, the MME of the network 220, depending on a current MME configuration and the maximum number of supported simultaneous PDN connections information (max_nsc_flag or max_nsc) transmitted by the wireless terminal and received by the network, may initiate a deactivation of a non-emergency PDN connection (TS23.401, s10.5.3) as per the requirements in TS23.401, s4.3.17.4.

In this case, the network 220 (in particular, the MME) knows how many, if any, packet connection(s) are available via the wireless terminal 200 because the network 220 has received the maximum number of supported simultaneous PDN connections information (max_nsc_flag or max_nsc) transmitted by the wireless terminal. Therefore the network can deactivate one or more active non-emergency connections if required, depending on how many (if any) packet connection(s) is/are available.

As indicated by arrow 232 (having a dashed line), PDN connectivity deactivation may or may not occur depending on the MME configuration and the maximum number of supported simultaneous PDN connections information (max_nsc_flag or max_nsc) transmitted by the wireless terminal and received by the network.

If the max_nsc_flag or max_nsc information indicates there are not enough packet connections available for an emergency connection to be established, then the network will initiate 222 de-activation 232 of one or more active packet connections so as to make available two packet connections required for an emergency connection to be established.

The network (MME) may or may not initiate deactivation of a non-emergency PDN connection and if it does so, resources will be freed for establishing a PDN connection for an emergency service.

Thus, if the "maximum number of supported simultaneous PDN connections flag" (max_nsc_flag) is set to ON or alternatively the threshold number (in this example the "maximum number of simultaneous PDN connections") has been indicated by the wireless terminal, the MME deactivates an active non-emergency PDN connection(s) in response to the network receiving the PDN connectivity request 231.

Preferably the MME deactivates the active non-emergency PDN connection(s) based on a priority list (like the bearers context prioritization list in the MME, see 3GPP TS23.401, s5.3.3.1 in step 21) so that the requested emergency PDN connection can be established.

If (as indicated by block 222 and arrow 232) the PDN connectivity deactivation is initiated by the network 220 , then the network 220 accepts the PDN connectivity request for emergency service (e.g. emergency call) by sending a PDN connectivity accept message, indicated by arrow 233, which is received by the wireless terminal 200, as per 3GPP TS23.401, s5.10.2.

Finally, as indicated by arrow 234, the wireless terminal 200 transmits a PDN connectivity report message to the network according to the 3GPP TS23.401, s5.10.2 procedure, the message 234 serving to complete an emergency packet (PDN) connection between the wireless terminal 200 and the network 220.

In Fig. 3, a wireless terminal 200 comprises a receiver 212, a transmitter 214, a processor 216 coupled to the receiver 212 and to the transmitter 214, and a memory 218 coupled to the processor 216. The processor 216 is configured to control the receiver 212 and the transmitter 214 according to instructions contained in the memory 218.

The receiver 212 of the wireless terminal 200 is arranged for receiving, via a wireless link 242 between the wireless terminal and the network apparatus, signalling data and/or traffic/media data transmitted by a network apparatus 220. The transmitter 214 of the wireless terminal 200 is arranged for transmitting signalling data and/or traffic/media data via a wireless communication link 244 between the wireless terminal and the network apparatus and is preferably arranged for performing transmission of information intended for one or more other network apparatus (not shown) via one or more other wireless links (not shown).

The communications link 242 used by the receiver 212 of the wireless terminal 200 and the communication link 244 used by the transmitter 214 of the wireless terminal 200 can be considered as the same communication link. Alternatively, the wireless communication link 242 used by the receiver 212 of the wireless terminal 200 can be considered as one link and the wireless communication link 244 used by the transmitter 214 of the wireless terminal 200 can be considered as another communication link. For example, the link 242 used by the receiver 212 can be considered as a down link and the link 244 used by the transmitter 214 can be considered as an uplink. Such use of communication links for transmitting and receiving signals are well known in the art and need not be discussed further.

The network apparatus 220 comprises a receiver 222, a transmitter 224, a processor226, and a memory228. The functions of the receiver222, transmitter224, processor 226 and memory 228 of the network apparatus 220 are similar to the respective functions of the receiver 212, transmitter 214, processor 216 and memory 218 of the wireless terminal 200. In use, the network apparatus 220 wirelessly transmits, via its transmitter 224 and wireless link 242, signals that are intended for the receiver 212 of the wireless terminal 200. Similarly the transmitter of wireless terminal 200 transmits one or more signals wirelessly that are intended for the network apparatus 220 via transmitter 214 and wireless link 244.

Preferably the receiver 212 of the wireless terminal 200 can receive signals transmitted by one or more further network apparatus (not shown). Similarly, preferably the transmitter 214 of the wireless terminal 200 can transmit signals intended for one or more further network apparatus (not shown).

Preferably the receiver 222 of the network apparatus 220 can receive signals transmitted by one or more further wireless terminals (not shown). Similarly, preferably the transmitter 224 of the network apparatus 220 can transmit signals intended for one or more further wireless terminal(s) (not shown).

In this example the network apparatus 220 forms part of a base station of a cellular communications network and the wireless terminal 200 is a cellular wireless terminal. However, it should be understood there may exist only two devices, illustrated as the wireless terminal 200 and the network apparatus 220 in Fig. 3. A wireless communication system comprising only two such devices or a small number of devices can benefit from the claimed features.

A base station controller (BSC) 330, coupled to the network apparatus 220, is arranged to route signals to/from the network apparatus 220 and to/from other such network apparatus (not shown). A mobile switching centre (MSC) 340 is arranged to route signals to/from the base station controller 330 and to/from other such base station controllers (not shown). A MME or SGSN 350 (depending on whether the network is E-UTRAN or UTRAN/GERAN) is arranged to control and route signals to/from the mobile switching centre 340 and to/from a public switched telephone network (PSTN) (not shown). The principles of operation of the base station controller 330, mobile switching centre 340 and MME or SGSN 350 are well know and need not be described further.

The above-described embodiments are applicable to UTRAN and GERAN (where the Activate PDP context request message of GERAN is an equivalent of the PDN connectivity request message of E-UTRAN). Clearly, the embodiments can be applied, with minor simple modification as required, to other RAN technologies.

The embodiments are also applicable to EPS bearer context in E-UTRAN and PDP context in UTRAN and GERAN that are often synonyms for PDN connection and PDP connection respectively.

The above-described embodiments, comprising the new parameter indication transmitted by the wireless terminal, are also applicable for other wireless terminal-initiated procedures such as, for example, a UE-requested bearer resource allocation message and a UE-requested bearer resource modification message in E-UTRAN and also an Activate Secondary PDP Context Request message and an MS initiated PDP context modification message in UTRAN or GERAN.

According to a variation of the above-described embodiments, the wireless terminal can indicate a maximum number of supported Data Radio Bearers (DRB) instead of, or in addition to, the maximum number of supported simultaneous PDN (or PDP) connections within the new indicating signal claimed in the appended claims.

Use of the new parameter will now be described in relation to a proposed modification of the existing PDN connectivity request message (3GPP TS23.401, s5.10.2).

a) max_nsc_flag - "maximum number of supported simultaneous PDN connections flag" by the wireless terminal (a logical value), a parameter that is set to ON by the wireless terminal when it initiates PDN connectivity request for emergency service AND the threshold number of supported simultaneous PDN connections is reached.

Alternatively, the wireless terminal could set this parameter to ON in one or more, or each, packet (PDN) connectivity request (not just the packet requests for emergency connection) when the threshold number of supported simultaneous PDN connections is reached.
OR
b) max_nsc - "Maximum Number of Supported [simultaneous PDN] Connections" [by the wireless terminal] parameter (a quantitive value) that is indicated by the wireless terminal when it initiates a packet (PDN) connectivity request for emergency AND the threshold (e.g. maximum) number of supported simultaneous PDN connections is reached.

Alternatively, the wireless terminal could indicate the threshold number of simultaneous supported PDN connections by the wireless terminal when a PDN connection for emergency is requested (regardless whether the threshold number of supported simultaneous PDN connections by the wireless terminal is reached or not) - for example every time a PDN connection for emergency is requested.

Another alternative is that the wireless terminal could indicate the threshold number of supported simultaneous PDN connections by the wireless terminal in one or more, or each, PDN connectivity request (regardless for emergency connection or not and regardless whether the maximum number of supported simultaneous PDN connections by the wireless terminal is reached or not).

When the network receives a PDN connectivity request message for emergency with the new parameter "maximum number of supported simultaneous PDN connections flag" (max_nsc_flag) set to ON or "maximum number of supported simultaneous PDN connections" (max_nsc) set to the threshold value, the network reliably deactivates enough active non-emergency PDN connection(s) (based on prioritizations) if the number of active PDN connections between the wireless terminal and the network has reached the threshold value, i.e. if the number of free or available packet connections is not enough to establish an emergency service.

Because the network entity takes the decision to de-activate one or more active packet connections, and the network entity is responsible for performing deactivation of active non-emergency packet connection(s) when the wireless terminal needs a packet connection for emergency and the wireless terminal has already reached its threshold number of supported simultaneous packet connections there are the following advantages:
1) The network (MME) has already got the capability for active PDN connections deactivation in different scenarios (for example when the wireless terminal changes the MME and the new MME, based on its configuration, may decide to deactivate non-emergency PDN connection(s), see TS23.401, s4.3.17.4). So, the tool and the use case for active PDN connection(s) deactivation is already there (in the 3GPP specifications/standards) and it is relatively easy to re-use it;
2) The network (MME) is the best-equipped entity for deciding which active PDN connection to deactivate. The MME would deactivate an active non-emergency PDN connection(s) based on a priority list (e.g. the bearers context prioritization list in the MME, see 3GPP TS23.401, s5.3.3.1 in step 21). This priority list is not available in the wireless terminals;
3) The network (MME) also has detailed information about the active PDN connections (GBR, QoS, bandwidth, activity pattern, APN and etc) that could be used for the active PDN connections prioritization and could as a consequence help in the decision which PDN connection to deactivate.
4) It is also possible that the emergency call is less delayed when the non-emergency PDN connection(s) deactivation is controlled by the network rather than the wireless terminal because the MME could deploy (implementation dependant) some parallelism in session creation and deactivation procedures within the network related to the emergency PDN connection establishment and to the PDN connection that is being deactivated.
5) In general, deactivation and release of connections are controlled by the network (only abnormal ones by the wireless terminal). Since there is no clear advantage to be gained by the wireless terminal initiating the deactivation of the non-emergency PDN connection in the above described scenario, then the network has responsibility for initiating the deactivation.

This application is based upon and claims the benefit of priority from United Kingdom patent application No. 1206481.2, filed on April 12, 2012, the disclosure of which is incorporated in its entirety by reference.

100 wireless terminal
120 network
200 wireless terminal
220 network
212 receiver
214 transmitter
216 processor
218 memory
222 receiver
224 transmitter
226 processor
228 memory
330 BSC
340 MSC
350 MME/SGSN

Claims

A wireless terminal for use in a wireless communication system comprising the wireless terminal and a network apparatus, the wireless terminal comprising:
means for wirelessly connecting to the network apparatus by means of one or more packet connections; and
means for wirelessly transmitting, for receiving by the network apparatus, an indicating signal providing an indication of a threshold number of packet connection(s) by which the wireless terminal can be connected to the network apparatus.
A wireless terminal as claimed in Claim 1, wherein the signal comprises a flag which provides the indication by indicating a relation between a current number of packet connection(s) by which the wireless terminal is already connected to the network apparatus and the threshold number.
A wireless terminal as claimed in Claim 2, wherein the relation between the current number of packet connection(s) and the threshold number is that the current number equals the threshold number, and the signal provides the indication dependant on the current number being equal to the threshold number.
A wireless terminal as claimed in any one of Claims 1 to 3, wherein the threshold number is a maximum number of packet connections by which the wireless terminal can be connected to the network apparatus at any one time or during a specified time period.
A wireless terminal as claimed in any one of Claims 1 to 4, wherein the indicating signal comprises a packet signalling message.
A wireless terminal as claimed in Claim 5, wherein the packet signalling message comprises an emergency packet signalling message.
A wireless terminal as claimed in any one of Claims 1 to 6, wherein the wireless communication system comprises a network which is a Universal Terrestrial Radio Access Network (UTRAN) or an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) or a GSM Evolved Radio Access Network (GERAN), and the network apparatus is part of the network, and wherein the one or more packet connections comprise a PDN connection or a PDP connection.
A wireless terminal as claimed any one of Claims 1 to 7, wherein the one or more packet connection(s) comprise an enhanced packet services (EPS) bearer context and/or a PDP context.
A wireless terminal as claimed in any one of Claims 1 to 8, wherein the indicating signal comprises a wireless terminal requested bearer resource allocation message and/or a wireless terminal requested bearer resource modification message and/or an Activate Secondary PDP Context Request message and/or a wireless terminal initiated PDP context modification message.
A network apparatus for use in a wireless communication system comprising a wireless terminal and the network apparatus, the network apparatus comprising:
means for wirelessly connecting to a wireless terminal by means of one or more packet connections;
means for wirelessly receiving a signal relating to a specified wireless terminal indicating a threshold number of packet connection(s) by which the network apparatus can be connected to the specified wireless terminal; and
means for, depending upon the threshold number, initiating deactivation of one or more current packet connections by which the network apparatus is connected to the specified wireless terminal so that an emergency packet signalling connection and an emergency packet media connection can be maintained between the network apparatus and the wireless terminal.
A network apparatus as claimed in Claim 10, wherein the signal comprises a flag which provides the indication by indicating a relation between a current number of packet connection(s) by which the wireless terminal is already connected to the network apparatus and the threshold number.
A network apparatus as claimed in Claim 11, wherein the relation between the current number of packet connection(s) and the threshold number is that the current number equals the threshold number, and the signal provides the indication dependant on the current number being equal to the threshold number.
A network apparatus as claimed in any one of Claims 10 to 12, wherein the threshold number is a maximum number of packet connections by which the wireless terminal can be connected to the network apparatus at any one time or during a specified time period.
A network apparatus as claimed in any one of Claims 10 to 13, wherein the indicating signal comprises a packet signalling message.
A network apparatus as claimed in Claim 14, wherein the packet signalling message comprises an emergency packet signalling message.
A network apparatus as claimed in any one of Claims 10 to 15, wherein the wireless communication system comprises a network which is a Universal Terrestrial Radio Access Network (UTRAN) or an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) or a GSM Evolved Radio Access Network (GERAN), and the network apparatus is part of the network.
A network apparatus as claimed in any one of Claims 10 to 16, wherein the one or more packet connection(s) comprise an enhanced packet services (EPS) bearer context and/or a PDP context.
A network apparatus as claimed in any one of Claims 10 to 17, wherein the indicating signal comprises a wireless terminal requested bearer resource allocation message and/or a wireless terminal requested bearer resource modification message and/or an Activate Secondary PDP Context Request message and/or a wireless terminal initiated PDP context modification message.
A method for use in a wireless terminal of a wireless communication system comprising the wireless terminal and a network apparatus, the method comprising:
wirelessly connecting to a network apparatus by means of one or more packet connections ; and
wirelessly transmitting, for receiving by the network apparatus, an indicating signal providing an indication of a threshold number of packet connection(s) by which the wireless terminal can be connected to the network apparatus.
A method as claimed in Claim 19, wherein the signal comprises a flag which provides the indication by indicating a relation between a current number of packet connection(s) by which the wireless terminal is already connected to the network apparatus and the threshold number.
A method as claimed in Claim 20, wherein the relation between the current number of packet connection(s) and the threshold number is that the current number equals the threshold number, and the signal provides the indication dependant on the current number being equal to the threshold number.
A method as claimed in any one of Claims 19 to 21, wherein the threshold number is a maximum number of packet connections by which the wireless terminal can be connected to the network apparatus at any one time or during a specified time period.
A method as claimed in any one of Claims 19 to 22, wherein the indicating signal comprises a packet signalling message.
A method as claimed in Claim 23, wherein the packet signalling message comprises an emergency packet signalling message.
A method as claimed in any one of Claims 19 to 24, wherein the wireless communication system comprises a network which is a Universal Terrestrial Radio Access Network (UTRAN) or an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) or a GSM Evolved Radio Access Network (GERAN), and the network apparatus is part of the network.
A method as claimed in any one of Claims 19 to 25, wherein the one or more packet connection(s) comprise an enhanced packet services (EPS) bearer context and/or a PDP context.
A method as claimed in any one of Claims 19 to 26, wherein the indicating signal comprises a wireless terminal requested bearer resource allocation message and/or a wireless terminal requested bearer resource modification message and/or an Activate Secondary PDP Context Request message and/or a wireless terminal initiated PDP context modification message.
A method for use in a network apparatus for use in a wireless communication system comprising a wireless terminal and the network apparatus, the method comprising:
wirelessly connecting to a wireless terminal by means of one or more packet connections;
wirelessly receiving a signal relating to a specified wireless terminal indicating a threshold number of packet connection(s) by which the network apparatus can be connected to the specified wireless terminal; and,
depending upon the threshold number, initiating deactivation of one or more current packet connections by which the network apparatus is connected to the specified wireless terminal so that an emergency packet signalling connection and an emergency packet media connection can be maintained between the network apparatus and the network apparatus.
A method as claimed in Claim 28, wherein the signal comprises a flag which provides the indication by indicating a relation between a current number of packet connection(s) by which the wireless terminal is already connected to the network apparatus and the threshold number.
A method as claimed in Claim 29, wherein the relation between the current number of packet connection(s) and the threshold number is that the current number equals the threshold number, and the signal provides the indication dependant on the current number being equal to the threshold number.
A method as claimed in any one of Claims 28 to 30, wherein the threshold number is a maximum number of packet connections by which the wireless terminal can be connected to the network apparatus at any one time or during a specified time period.
A method as claimed in any one of Claims 28 to 31, wherein the indicating signal comprises a packet signalling message.
A method as claimed in Claim 32, wherein the packet signalling message comprises an emergency packet signalling message.
A method as claimed in any one of Claims 28 to 33, wherein the wireless communication system comprises a network which is a Universal Terrestrial Radio Access Network (UTRAN) or an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) or a GSM Evolved Radio Access Network (GERAN), and the network apparatus is part of the network.
A method as claimed in any one of Claims 28 to 34, wherein the one or more packet connection(s) comprise an enhanced packet services (EPS) bearer context and/or a PDP context.
A method as claimed in any one of Claims 28 to 35, wherein the indicating signal comprises a wireless terminal requested bearer resource allocation message and/or a wireless terminal requested bearer resource modification message and/or an Activate Secondary PDP Context Request message and/or a wireless terminal initiated PDP context modification message.
A wireless terminal substantially as described herein and/or substantially as illustrated in one or more of the accompanying drawings.
A network apparatus substantially as described herein and/or substantially as illustrated in one or more of the accompanying drawings.
A method substantially as described herein and/or substantially as illustrated in one or more of the accompanying drawings.