GB2501110A - Packet based emergency connection management - Google Patents

Abstract

A wireless terminal and a network apparatus can connect to each other by means of one or more packet connections, i.e. Packet Data Network (PDN) or Packet Data Protocol (PDP) connections. Typically there is a maximum threshold of connections that may be set up with a wireless device. If this threshold is reached, it may not be possible to set up an additional emergency packet connection. In this case, when a wireless terminal requests an emergency packet connection it also transmits a signal to a network apparatus indicating a threshold flag or maximum number of packet connection(s) which the wireless terminal can handle. If the threshold flag indicates the maximum number of connections is reached, the network apparatus initiates deactivation of one or more current packet connections, so that an emergency packet signalling connection and an emergency packet media connection can be established between the wireless terminal 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 1523.060, s5.1O).

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 (SOSN) (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 orSGSN 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 ((3W) (tbr E-UTRAN) or Gateway OPRS Support Node (GGSN) (for UTBAN). The MME or 505)4 Emergency Configuration Data may also contain the statically configured PDN OW or GOSN for the Emergency APN.

A wireless terminal that is in limited service state, as specified in 3GPP 1'S 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 ocatcd supports emergency services over E-UI'RAN or LITRAN.

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 torn of an Emergency Seivice Support indicator in the Aach 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 I'S 36331 when the wireless terminal requests an RRC connection in relation to an emergency session, For successful emergency service suppoit on th.e packet domain (in E-T.J'FRAN and UTRAN) the wireless terminal needs to support at least one PDN connection (fcr E-UTRAN) or P1)1> 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 tenninal is ii. This maximum nur.nher of j simultaneous PUN connections is aligned with GPRS requirements, in which the maximum number of Network Layer Service Access Point identiflers (NSAPIs) does not allow more Lhan 1.1 simuhaneous PUP connections.

in practice typically the network and the wireless terminal, do not support this maximum number of simultaneous PUN/PUP connections. A practical maximum for simultaneous PUN connections supported by the wireless terminM may be 3 due to Data Radio Bearer (DRB) constraints (see TS3633 1, siLl). The feature of multiple PDN/PDP connections support itself is an optional feature in 3GPP (see TS21401, s5A0).

A \ireIess terminal, while it is in limited service state, has no active connections. A terminal an.d network which together support the multi PDNPDP connection feature would support at east two packet connections. Therefore the tact that an emergency connection requires at least two srnultaneous packet (PDN/PDP) connections would not present a problem when the wireless terminal is in limited service state and the wireless termin& and network both support the multi PDN!.PDP connection feature.

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

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

FTG I 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 hnes 105. 125 joined to the wireless terminal 100 and network 120 respectivdy.

This figure illustrates the cuiTent process of establishing an emergency connection on the packet domain according to the EUTRAN standard 3GPP TS23.401, sS,iO.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 cal]. i'he wireless tenrund 100 initiates an emergency PDN connection if the wireless terminal's threshold (in this case maximum) number of supported simultaneous PDi' 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 cati) there is a problem, as explained above, whereby the wireless terminal cannot request an emergency call on the packet domain.

The E4JTR.AN standard 3GPP TS23.40l 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.iO.2, In block 122 (bounded by a dashed hne), when the network 120 receives the PDN connectivhy request 13 1, the MME of the network 120 may, depending on a current MME configuration, initiate a deactivation of a nonemergency PDN connection (TS23.40i, sI 0.5.3) as perthe requirements in TS23.401, s4.3.17.4. Flowever, 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 he supported by the wireless terminal.

As indicated by arrow 132 (hsving 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 nonemergency PDN connection. Only if it does so will resources be freed for establishing a PDN connection for an emergency.

S

if (as indicated by block 122 and arrow 132) a PDN connectivity deactivation is initiated by the network, then th.e network 1 20 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 3CiPP 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.i0,2. The message 134 serves to complete an emergency packet (PDN) connectmn between the wireless terminal 100 and the network I 20.

It is clear from the above that, according to the current state of the art, when an emergency iC 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 he provided by the network. Tins is a very undesirable and poientiaily unsafe situation.

United States Patent Application 2011031754.5 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 arid 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 downhnk hit rate; and reestablishing the RAB for the PDP context with the maximum uplink bit rate and the maximum down.link bit rate reconfigured as the original non-zero values after the request signal has been sent. Tha.t 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 downiink hit 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) betbre proceeding with the emergency connection iflwhcn the maximum number of PDN connections supported by the wireless terminal is reached.

Alternatively, another solution might he 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 iflwhen the maximum number of PDN connections supported by the wireless terminal is reached.

However, a problem with these two possible solutions is that the terminal is not the entity that is best equipped to take a decrsion 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 cjrcumstances based on PDN connections prioritisation (see TS 21401, sS.3J. I, step 21) which (the priority list) is not avaflable in the wireless terminals.

Also, connections deactivations and releases are normally controlled by the network.

E!he present invention seeks to provide for a wireless terminal, a network apparatus and associated methods having advantages over knowi such wireless terminals, network apparatus and methods.

In particular, the present invention seeks to address the above-described problems arid 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 commcnication 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 br wirelessly transmitting, for receiving by the network apparatus. a sigiai 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 *f-r use i.n a wireless communication system comprising a wireless terminal and the network apparatus, the network apparatus comprising: means for wireiessiy 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-specied wireiess 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 beer: reached, that the threshold number of connections has indeed been reached because the network knows how many active connections currently ex:st.

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, lO i.e when the wireless terminal does not have enough free packet connection(s) available to provide transmissionlrecepti.on of emergency signalling and emergency media.

The inventive features provide advantages over other alternative solutions briefly described above, thr example the solution in which the terminal itse]f takes a decision and deactivates or locally releases an active nonernergency PDN connection so that an emergency connection can he established.

It is advantageous for the network to take the decision to perfonn 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.

Features and advantages of the invention witi now be described by way of example only and with reference to the appended drawings, in which: FiG, 1 is an event diagram illustrating the cunent process of establishing an emergency connection on the packet domain according to the &UTRAN standard 3GPP TS23.401, s5.lO,2; and 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 ananged for operating according to the invention.

S

According to an embodiment, a new pararrieter is included in the PDN connectivity request message (see 3GPP TS23.401, sS.102). Optionafly, this parameter can he indicated by a flag which may be called "maximum number of supported simultaneous PDN connections flag" (max use 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 connectjon) 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 vaue of this parameter would be set to the maximum number of simultaneous PDN connections supported by the wireless terminal, on I S each occasion when a PDN connection is requested for emergency service arid 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 fin 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 recrives a PDN connectivity request fUr emergency and the network determines whether this flag indicates that the wireless terminal has reached its simultaneous PDN connectivity support limit'niaximum, Accordin.g to an embodiment, the network MME) releases or terminates an active non emergency PDN connection(s) based on a priority list (fbr example as per the hearers context prioritization listin the MME, see 3GPP TS21401, s533,1 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 TS2I4OI, s.S10.2, The event diagram of FiG. 2 shows operations (blocks 202, 222) performed by a wireless termin& 200 and a network 220 and signals, represented by horizontal arrows 23l234, 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 tenninal and network respectively.

The proposed new process shown in FIG, 2 is in keeping with, and would require minimal modification to, the EUTRAN standard 3GPP TS23 AOl, s5.102.

in a first stage of the new process (as represented by the input of block 202) the wireless termina.i 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 simuhaneous 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 he 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 rise 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 termina.l may set the tiag to ON and transmit the flag when it requests PDN connectivity for ony 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 he known as the "maximum number of supported simultaneous PDN connections" (maxnsc).

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 supoorted simultaneous PDN connections is reached, Another alternative is that this max nsc parameter could he set (and indicated to the network by being transmitted) in one or each PDN connectivity request. Such a connectivity request 1 5 may be a connectivity request far a noneniergency 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 23 L The Request TTe paralTieter of the PDN connectivity request 231 is set to "Emergency" -see 3GPP TS23.$0i, s5.l0.2, 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 (hounded 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 cunent 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, 510.5.3) as per the requirements in TS23.401, s4317.4, n 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 (maxnsc flag or max usc) transmitted by the wirekss termina' . 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 (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 he established, then the network will initiate 222 dc-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 he fleed 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 thresho'd 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' *tii.e hearers context prioritization list in the MME, see 30ff TS23401, aS 3.3.1 in step 21) so that the requested emergency PDN connection can be established.

If (as indicated by block fl2 and arrow 232) the PDN connectivity deactivation is initiated by [lie network 220 then the network 220 accepts the PDN connectivity request for emergency

IL

service (e.g. emergency call) by sending a PDN connectivity accept message, indicated by arrow 233, which is received by the wiretess terminal 200, as per 3GPP TS23,401, sS.l 0.2.

Finally, as indicated by arrow 234, the wireless Lerminal 200 transmits a PDN connectivity report message to the network according to the 3GPP TS23401, sS,i0.2 procedure, the message 234 serving to complete an emergency packet (PDN) connection between the wreiess terminal 200 and the network 220.

In FRi. 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 21$ 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 22, The transmitter 214 of the wireless terminal 200 is arranged for transmitting siçialllng 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 wirekss terminal 200 can be considered as the same communication link. itcrnativeiy, the wireless communication link 242 used by the receiver 212 of the wireless terminal 200 can he considered as one link and the wireess communication link 244 used by the transmitter 214 of the wireless terminal 200 can be considered as another communication ink. For example, the link 242 used by the receiver 21.2 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 thr 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 processor 126, and a memory 128. The functions of the receiveri22, transmitter224, processor 126 and memory 128 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, vi.a 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 tennin.ai 200 transmits one or more signa's 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 sign&s 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 ce!lular communications network and the wireless terminal 200 is a cellular wirdess terminal.

i-iowever, it should be understood there may exist only two devices, illustrated as the wireless is terminal 200 and the network apparatus 220 in FIG. 3. A wireless communicaiion system comprising only two such devices or a small number of devices can benefit from the claimed features, A base station controder (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 n:iohiie switching centre 340 and to/from a public switched teiephone network (PS'I'N) (not shown). The principles of operation of the base station controller 330, mobile switching centre $40 and MME or SGSN 350 are well know and need not be described thrther.

The abovedescribed embodiments are applicable to UTRAN and GE.RAN (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 ahovedescribed embodiments, comprising the new parameter indication transmitted by S the wireless terminal, are also arphcahie for other wireless terminal-4nitiated procedures such as, for example. a L1&requested bearer resource aflocation message and a U&requested bearer resource modification message in &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 (IDRB) 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 TS23.40l, s5,i02).

a) maxnsc flag "maximum number of supported simultaneous PDN coruiections flag" by the wireless terminal (a logical value), a parameter that is set to ON by the wirdess 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, nacket (PDN) connectivity request (not just the packet requests f.or emergency connection) when the threshold number of supported simultaneous PDN connections is reached;

OR

b) maxnsc -"Maximum Number of Supported [sirm.dtaneous PDNI Connections" [by the wirekss terminal] ararneter (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) numoer 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 Pl)N connectivity request message for emergency with the new parameter "maximum number of supported simultaneous PDN connections flag" (mwçnscflag) 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.l7.4). 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 piioritization list in the MME, see 3GPP TS23.401, s5.3.3.l 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 (013k, 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 contmllcd 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 establishnient 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 P1*4 connection in the above described scenario, then the network has responsibility for initiating the deactivation.

Claims (5)

1. CLA[MS: 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 networx apparatus by means of one or more packet connections; and means for wirelessly transmitting, for receiving by the network apparatus, art 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.
2. 2. 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) iy which the wireless termina! is already connected to the network apparatus and the threshold number.
3. 3. A wireless terminal as claimed in Claim 2, wherein the relation between the current number of packet connection(s) and the thresho'd 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.
4. 4. A wireless terminal as claimed in any oreceding daim, wherein the threshold number is a maximum number of packet connections by which the wireless terminal can he connected to the network apparatus at any one time or during a specified time period.
5. 5. A network apparatus as claimed in Claim 14, wherein the packet signalling message comprises an emergency packet signalling message.

   15, A network apparatus as claimed. in any one of Claims 10 to 15, wherein the wireless commuitication system comprises a network which is a Universal Terresi.rial Radio Access Network (UTRAN) or an Evolved Universal Terrestrial Radio Access Network (EWTRAN) or a GSM Evolved Radio Access Network (GERAN\ and the network apparatus is part of the network.17. A network apparatus as claimed in any one of Claims 1 0 to 16, wherein the one or more packet connection(s) comprise an enhanced packet services (FF5) hearer context andIor a PEW context.18. 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.19. 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 hy means of one or more packet connections; and *l 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 temilnal can be connected to the network apparatus.20. 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.21. A methoa as claimed in Claim 20, wherein the relation between the current number of packet connection(s) and the threshold number is that the ci.irrent number equals the threshold.number, and the signal provides the indication dependant on the current number being equal to the threshold number, 22. A method as claimed in any one of Claims 19-21, wherein the threshold number is a maximum number of p' cket connections by which the wireless termina' can he connected to the network apparatus at any one time or during a specified time period.23. A method as claimed in any one of Claims 19-22, wherein the indicating signal comprises a packet signalling message.24. A method as claimed in Claim 23. wherein the pack. .etsina1ing message comprises an emergency packet signalhng message.25. A method as claimed in one of Claims 19-24, 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.26. A method as claimed in any one of Claims 19-25, wherein the one or more packet connection(s) comprise an enhanced packet seriices (EPS) bearer context and/or a PDP context.27. A method as claimed in one of Claims 19-26, wherein the indicating signal comprises a wireless termina' requested bearer resource allocation message andior a wireless tenninal requested bearer resource modification message and/or an Activate Secondary PDP Context Request message and/or a wireless terminal initiated PUP context modification message.28. A method tar use in a network apparatus for use in a wireless communication system comprising a wire]ess terminal and the network apparatat, the r.neth.od 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 he 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 he maintained between the network apparatus and the network apparatus.29. 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.30. 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.31. A method as claimed in any one of Claims 283O, wherein the threshold number is a maximum number of packet connections by which the wireless terminal can he connected to the network apparatus at any one time or during a. specified time period.32. A method as claimed in any one of Claims 28-31, wherein the indicating signal comprises a packet signalling message.33. A method as claimed in Claim 32, wherein the packet signalling message comprises an emergency packet signalling message.34. A method as claimed in one of Claims 2833, 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 (}SM Evolved Radio Access Network (GERAN), and the network apparatus is part of the network.35. A method as claimed in any one of Claims 28-34, wherein the one or more packet connection(s) comprise an enhanced packet services (EPS) bearer context and/or a PDP context.36. A method as claimed in one of Claims 28-35, 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 tenninal initiated PDP context modification message.37. A wireless terminal substantially as described herein and/or substantially as illustrated in one or more of the accompanying drawings.38. A network apparatus substantially as described herein and/or substantially as illustrated in one or more of the accompanying drawings.39. A method substantially as described herein and/or substantially as illustrated in one or more of the accompanying drawings.

   5, A wireless terminal as claimed in any preceding claim, wherein the indicating signal comprises a packet signalling message.

   6. A wireless terminal as claimed in C!ahn 5, wherein the packet signalling message comprises an emergency packet signailin.g message.

   7. A wireless terminal as claimed in any preceding claim, 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 (EIJTRAN) 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.

   8. A wireless terminal as claimed in any preceding claim, wherein the one or more packet connection(s) comprise an enhanced packet services (EPS) bearer context and/or a PDP context.

   9. A wireless terminal as claimed in any preceding claim, 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 PEW context modification message.

   10. 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 network apparatus.

   11. 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.

   12. 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.

   13. A network apparatus as claimed in any one of Claims 10 to 12, wherein the thresho]d 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.14. A network apparatus as claimed in any one of Claims 10 to 13, wherein the indicating signal comprises a packet signalling message.