Transmitting keep-alive packets on behalf of a mobile communications device within a wireless communications system

BACKGROUND OF THE INVENTION

00011. Field of the Invention

0002Embodiments of the invention relate to transmitting keep-alive packets on behalf of a mobile communications device within a wireless communications system.

00032. Description of the Related Art

0004Wireless communication systems have developed through various generations, including a first-generation analog wireless phone service (1G), a second-generation (2G) digital wireless phone service (including interim 2.5G and 2.75G networks) and a third-generation (3G) high speed data/Internet-capable wireless service. There are presently many different types of wireless communication systems in use, including Cellular and Personal Communications Service (PCS) systems. Examples of known cellular systems include the cellular Analog Advanced Mobile Phone System (AMPS), and digital cellular systems based on Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), the Global System for Mobile access (GSM) variation of TDMA, and newer hybrid digital communication systems using both TDMA and CDMA technologies.

0005The method for providing CDMA mobile communications was standardized in the United States by the Telecommunications Industry Association/Electronic Industries Association in TIA/EIA/IS-95-A entitled “Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System,” referred to herein as IS-95. Combined AMPS & CDMA systems are described in TIA/EIA Standard IS-98. Other communications systems are described in the IMT-2000/UM, or International Mobile Telecommunications System 2000/Universal Mobile Telecommunications System, standards covering what are referred to as wideband CDMA (W-CDMA), CDMA2000 (such as CDMA2000 1xEV-DO standards, for example) or TD-SCDMA.

0006In W-CDMA wireless communication systems, user equipments (UEs) receive signals from fixed position Node Bs (also referred to as cell sites or cells) that support communication links or service within particular geographic regions adjacent to or surrounding the base stations. Node Bs provide entry points to an access network (AN)/radio access network (RAN), which is generally a packet data network using standard Internet Engineering Task Force (IETF) based protocols that support methods for differentiating traffic based on Quality of Service (QoS) requirements. Therefore, the Node Bs generally interact with UEs through an over the air interface and with the RAN through Internet Protocol (IP) network data packets.

0007In wireless telecommunication systems, Push-to-talk (PTT) capabilities are becoming popular with service sectors and consumers. PTT can support a “dispatch” voice service that operates over standard commercial wireless infrastructures, such as W-CDMA, CDMA, FDMA, TDMA, GSM, etc. In a dispatch model, communication between endpoints (e.g., UEs) occurs within virtual groups, wherein the voice of one “talker” is transmitted to one or more “listeners.” A single instance of this type of communication is commonly referred to as a dispatch call, or simply a PTT call. A PTT call is an instantiation of a group, which defines the characteristics of a call. A group in essence is defined by a member list and associated information, such as group name or group identification.

SUMMARY

0008In an embodiment, a mobile communications device (MCD) is positioned within an internal network that is separated from an external network by network address translation (NAT) and/or a firewall. The MCD establishes settings with the NAT and/or firewall by which the MCD can be contacted through from the external network. The settings are configured to be disabled by the NAT and/or firewall after a threshold period of traffic inactivity. An application server receives information associated with the settings, and instructs an assisting application server (AAS) within the internal network to transmit keep-alive packets on behalf of the MCD so as to maintain the settings for the MCD. The AAS receives the instructions from the application server, and instructs an assisting wireless communications device (WCD) (e.g., using the same air interface mechanism as the MCD located within the internal network) to transmit keep-alive packets on behalf of the MCD. The WCD then transmits the keep-alive packets in accordance with the instructions.

BRIEF DESCRIPTION OF THE DRAWINGS

0009A more complete appreciation of embodiments of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings which are presented solely for illustration and not limitation of the invention, and in which:

0010<figref idref="DRAWINGS">FIG. 1</figref> is a diagram of a wireless network architecture that supports UEs and access networks in accordance with at least one embodiment of the invention.

0011<figref idref="DRAWINGS">FIG. 2A</figref> illustrates the core network of <figref idref="DRAWINGS">FIG. 1</figref> according to an embodiment of the present invention.

0012<figref idref="DRAWINGS">FIG. 2B</figref> illustrates the core network of <figref idref="DRAWINGS">FIG. 1</figref> according to another embodiment of the present invention.

0013<figref idref="DRAWINGS">FIG. 2C</figref> illustrates an example of the wireless communications system of <figref idref="DRAWINGS">FIG. 1</figref> in more detail.

0014<figref idref="DRAWINGS">FIG. 3</figref> is an illustration of an user equipment (UE) in accordance with at least one embodiment of the invention.

0015<figref idref="DRAWINGS">FIG. 4</figref> illustrates an example of routing of keep-alive packets from a plurality of UEs in a core network.

0016<figref idref="DRAWINGS">FIG. 5A</figref> illustrates a process by which an application server sends mobile-terminated data to a plurality of client applications on a given UE.

0017<figref idref="DRAWINGS">FIG. 5B</figref> illustrates another process by which the application server sends mobile-terminated data to a plurality of client applications on the given UE.

0018<figref idref="DRAWINGS">FIG. 6A</figref> illustrates a wireless communications system in accordance with an embodiment of the invention.

0019<figref idref="DRAWINGS">FIG. 6B</figref> illustrates an example of routing of keep-alive packets from a plurality of UEs in a packet core of <figref idref="DRAWINGS">FIG. 6A</figref> in accordance with an embodiment of the invention.

0020<figref idref="DRAWINGS">FIG. 7A</figref> illustrates a process by which the application server sends mobile-terminated data to one or more client applications on a given UE in accordance with an embodiment of the invention.

0021<figref idref="DRAWINGS">FIG. 7B</figref> illustrates a continuation of the process of <figref idref="DRAWINGS">FIG. 7A</figref> in accordance with an embodiment of the invention.

0022<figref idref="DRAWINGS">FIG. 7C</figref> illustrates a continuation of the process of <figref idref="DRAWINGS">FIG. 7A</figref> in accordance with another embodiment of the invention.

0023<figref idref="DRAWINGS">FIG. 7D</figref> illustrates yet another continuation of the process of <figref idref="DRAWINGS">FIG. 7A</figref> in accordance with another embodiment of the invention.

DETAILED DESCRIPTION

0024Aspects of the invention are disclosed in the following description and related drawings directed to specific embodiments of the invention. Alternate embodiments may be devised without departing from the scope of the invention. Additionally, well-known elements of the invention will not be described in detail or will be omitted so as not to obscure the relevant details of the invention.

0025The words “exemplary” and/or “example” are used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” and/or “example” is not necessarily to be construed as preferred or advantageous over other embodiments. Likewise, the term “embodiments of the invention” does not require that all embodiments of the invention include the discussed feature, advantage or mode of operation.

0026Further, many embodiments are described in terms of sequences of actions to be performed by, for example, elements of a computing device. It will be recognized that various actions described herein can be performed by specific circuits (e.g., application specific integrated circuits (ASICs)), by program instructions being executed by one or more processors, or by a combination of both. Additionally, these sequence of actions described herein can be considered to be embodied entirely within any form of computer readable storage medium having stored therein a corresponding set of computer instructions that upon execution would cause an associated processor to perform the functionality described herein. Thus, the various aspects of the invention may be embodied in a number of different forms, all of which have been contemplated to be within the scope of the claimed subject matter. In addition, for each of the embodiments described herein, the corresponding form of any such embodiments may be described herein as, for example, “logic configured to” perform the described action.

0027A High Data Rate (HDR) subscriber station, referred to herein as a user equipment (UE), may be mobile or stationary, and may communicate with one or more access points (APs), which may be referred to as Node Bs. A UE transmits and receives data packets through one or more of the Node Bs to a Radio Network Controller (RNC). The Node Bs and RNC are parts of a network called a radio access network (RAN). A radio access network can transport voice and data packets between multiple UEs.

0028The radio access network may be further connected to additional networks outside the radio access network, such core network including specific carrier related servers and devices and connectivity to other networks such as a corporate intranet, the Internet, public switched telephone network (PSTN), a Serving General Packet Radio Services (GPRS) Support Node (SGSN), a Gateway GPRS Support Node (GGSN), and may transport voice and data packets between each UE and such networks. A UE that has established an active traffic channel connection with one or more Node Bs may be referred to as an active UE, and can be referred to as being in a traffic state. A UE that is in the process of establishing an active traffic channel (TCH) connection with one or more Node Bs can be referred to as being in a connection setup state. A UE may be any data device that communicates through a wireless channel or through a wired channel. A UE may further be any of a number of types of devices including but not limited to PC card, compact flash device, external or internal modem, or wireless or wireline phone. The communication link through which the UE sends signals to the Node B(s) is called an uplink channel (e.g., a reverse traffic channel, a control channel, an access channel, etc.). The communication link through which Node B(s) send signals to a UE is called a downlink channel (e.g., a paging channel, a control channel, a broadcast channel, a forward traffic channel, etc.). As used herein the term traffic channel (TCH) can refer to either an uplink/reverse or downlink/forward traffic channel.

0029<figref idref="DRAWINGS">FIG. 1</figref> illustrates a block diagram of one exemplary embodiment of a wireless communications system <b>100</b> in accordance with at least one embodiment of the invention. System <b>100</b> can contain UEs, such as cellular telephone <b>102</b>, in communication across an air interface <b>104</b> with an access network or radio access network (RAN) <b>120</b> that can connect the UE <b>102</b> to network equipment providing data connectivity between a packet switched data network (e.g., an intranet, the Internet, and/or core network <b>126</b>) and the UEs <b>102</b>, <b>108</b>, <b>110</b>, <b>112</b>. As shown here, the UE can be a cellular telephone <b>102</b>, a personal digital assistant <b>108</b>, a pager <b>110</b>, which is shown here as a two-way text pager, or even a separate computer platform <b>112</b> that has a wireless communication portal. Embodiments of the invention can thus be realized on any form of UE including a wireless communication portal or having wireless communication capabilities, including without limitation, wireless modems, PCMCIA cards, personal computers, telephones, or any combination or sub-combination thereof. Further, as used herein, the term “UE” in other communication protocols (i.e., other than W-CDMA) may be referred to interchangeably as an “access terminal”, “AT”, “wireless device”, “client device”, “mobile terminal”, “mobile station” and variations thereof.

0030Referring back to <figref idref="DRAWINGS">FIG. 1</figref>, the components of the wireless communications system <b>100</b> and interrelation of the elements of the exemplary embodiments of the invention are not limited to the configuration illustrated. System <b>100</b> is merely exemplary and can include any system that allows remote UEs, such as wireless client computing devices <b>102</b>, <b>108</b>, <b>110</b>, <b>112</b> to communicate over-the-air between and among each other and/or between and among components connected via the air interface <b>104</b> and RAN <b>120</b>, including, without limitation, core network <b>126</b>, the Internet, PSTN, SGSN, GGSN and/or other remote servers.

0031The RAN <b>120</b> controls messages (typically sent as data packets) sent to a RNC <b>122</b>. The RNC <b>122</b> is responsible for signaling, establishing, and tearing down bearer channels (i.e., data channels) between a Serving General Packet Radio Services (GPRS) Support Node (SGSN) and the UEs <b>102</b>/<b>108</b>/<b>110</b>/<b>112</b>. If link layer encryption is enabled, the RNC <b>122</b> also encrypts the content before forwarding it over the air interface <b>104</b>. The function of the RNC <b>122</b> is well-known in the art and will not be discussed further for the sake of brevity. The core network <b>126</b> may communicate with the RNC <b>122</b> by a network, the Internet and/or a public switched telephone network (PSTN). Alternatively, the RNC <b>122</b> may connect directly to the Internet or external network. Typically, the network or Internet connection between the core network <b>126</b> and the RNC <b>122</b> transfers data, and the PSTN transfers voice information. The RNC <b>122</b> can be connected to multiple Node Bs <b>124</b>. In a similar manner to the core network <b>126</b>, the RNC <b>122</b> is typically connected to the Node Bs <b>124</b> by a network, the Internet and/or PSTN for data transfer and/or voice information. The Node Bs <b>124</b> can broadcast data messages wirelessly to the UEs, such as cellular telephone <b>102</b>. The Node Bs <b>124</b>, RNC <b>122</b> and other components may form the RAN <b>120</b>, as is known in the art. However, alternate configurations may also be used and the invention is not limited to the configuration illustrated. For example, in another embodiment the functionality of the RNC <b>122</b> and one or more of the Node Bs <b>124</b> may be collapsed into a single “hybrid” module having the functionality of both the RNC <b>122</b> and the Node B(s) <b>124</b>.

0032<figref idref="DRAWINGS">FIG. 2A</figref> illustrates the core network <b>126</b> of <figref idref="DRAWINGS">FIG. 1</figref> according to an embodiment of the present invention. In particular, <figref idref="DRAWINGS">FIG. 2A</figref> denotes the core network or packet core <b>126</b> as <b>126</b>A, whereby the core network <b>126</b>A corresponds to a General Packet Radio Services (GPRS) core network implemented within a W-CDMA system. In the embodiment of <figref idref="DRAWINGS">FIG. 2A</figref>, the core network <b>126</b>A includes a Serving GPRS Support Node (SGSN) <b>160</b>, a Gateway GPRS Support Node (GGSN) <b>165</b> and a Network Address Translation (NAT) Firewall <b>172</b>. The components of the core network <b>126</b>A are connected to an external data packet network (or Internet) <b>175</b>, and through the Internet <b>175</b> are further connected to an application server <b>170</b> (shown in <figref idref="DRAWINGS">FIG. 2B</figref>). However, it is appreciated that portions of the Internet <b>175</b> and/or other components may be located inside of the core network <b>126</b>A in alternative embodiments.

0033Generally, GPRS is a protocol used by Global System for Mobile communications (GSM) phones for transmitting Internet Protocol (IP) packets. The GPRS Core Network (e.g., the GGSN <b>165</b> and one or more SGSNs <b>160</b>) is the centralized part of the GPRS system and also provides support for W-CDMA based 3G networks. The GPRS core network is an integrated part of the GSM core network, provides mobility management, session management and transport for IP packet services in GSM and W-CDMA networks.

0034The GPRS Tunneling Protocol (GTP) is the defining IP protocol of the GPRS core network. The GTP is the protocol which allows end users (e.g., UEs) of a GSM or W-CDMA network to move from place to place while continuing to connect to the internet as if from one location at the GGSN <b>165</b>. This is achieved transferring the subscriber's data from the subscriber's current SSGN <b>160</b> to the GGSN <b>165</b>, which is handling the subscriber's session.

0035Three forms of GTP are used by the GPRS core network; namely, (i) GTP-U, (ii) GTP-C and (iii) GTP′ (GTP Prime). GTP-U is used for transfer of user data in separated tunnels for each packet data protocol (PDP) context. GTP-C is used for control signaling (e.g., setup and deletion of PDP contexts, verification of GSN reachability, updates or modifications such as when a subscriber moves from one SGSN to another, etc.). GTP′ is used for transfer of charging data from GSNs to a charging function.

0036Referring to <figref idref="DRAWINGS">FIG. 2A</figref>, the GGSN <b>165</b> acts as an interface between the GPRS backbone network (not shown) and the external packet data network, or Internet <b>175</b>. The GGSN <b>165</b> extracts the packet data with associated packet data protocol (PDP) format (e.g., IP or PPP) from the GPRS packets coming from the SGSN <b>160</b>, and sends the packets out on a corresponding packet data network. In the other direction, the incoming data packets are directed by the GGSN <b>165</b> to the SGSN <b>160</b> which manages and controls the Radio Access Bearer (RAB) of the destination UE served by the RAN <b>120</b>. Thereby, the GGSN <b>165</b> stores the current SGSN address of the target UE and his/her profile in its location register (e.g., within a PDP context). The GGSN is responsible for IP address assignment and is the default router for the connected UE. The GGSN also performs authentication and charging functions.

0037The SGSN <b>160</b> is representative of one of many SGSNs within the core network <b>126</b>A, in an example. Each SGSN is responsible for the delivery of data packets from and to the UEs within an associated geographical service area. The tasks of the SGSN <b>160</b> includes packet routing and transfer, mobility management (e.g., attach/detach and location management), logical link management, and authentication and charging functions. The location register of the SGSN stores location information (e.g., current cell, current VLR) and user profiles (e.g., IMSI, PDP address(es) used in the packet data network) of all GPRS users registered with the SGSN <b>160</b>, for example, within one or more PDP contexts for each user or UE. Thus, SGSNs are responsible for (i) de-tunneling downlink GTP packets from the GGSN <b>165</b>, (ii) uplink tunnel IP packets toward the GGSN <b>165</b>, (iii) carrying out mobility management as UEs move between SGSN service areas and (iv) billing mobile subscribers. As will be appreciated by one of ordinary skill in the art, aside from (i)-(iv), SGSNs configured for GSM/EDGE networks have slightly different functionality as compared to SGSNs configured for W-CDMA networks.

0038Referring to <figref idref="DRAWINGS">FIG. 2A</figref>, the RAN <b>120</b> (e.g., or UTRAN, in Universal Mobile Telecommunications System (UMTS) system architecture) communicates with the SGSN <b>160</b> via an Iu interface, with a transmission protocol such as Frame Relay or IP. The SGSN <b>160</b> communicates with the GGSN <b>165</b> via a Gn interface, which is an IP-based interface between SGSN <b>160</b> and other SGSNs (not shown) and internal GGSNs, and uses the GTP protocol defined above (e.g., GTP-U, GTP-C, GTP′, etc.). While not shown in <figref idref="DRAWINGS">FIG. 2A</figref>, the Gn interface is also used by the Domain Name System (DNS). The GGSN <b>165</b> is connected to a Public Data Network (PDN) (not shown), and in turn to the Internet <b>175</b>, via a Gi interface with IP protocols either directly or through a Wireless Application Protocol (WAP) gateway.

0039The PDP context is a data structure present on both the SGSN <b>160</b> and the GGSN <b>165</b> which contains a particular UE's communication session information when the UE has an active GPRS session. When a UE wishes to initiate a GPRS communication session, the UE must first attach to the SGSN <b>160</b> and then activate a PDP context with the GGSN <b>165</b>. This allocates a PDP context data structure in the SGSN <b>160</b> that the subscriber is currently visiting and the GGSN <b>165</b> serving the UE's access point.

0040Referring to <figref idref="DRAWINGS">FIG. 2A</figref>, the NAT/Firewall <b>172</b> is positioned between the GGSN <b>165</b> and the Internet <b>175</b>. The NAT/Firewall <b>172</b> separates the core network <b>126</b>A from the Internet <b>175</b> and/or other core networks. For example, the NAT/Firewall <b>172</b> may perform NAT functionality such that network address information in datagram (IP) packet headers that traverse the NAT-portion are modified such that outgoing Internet Protocol (IP) packets appear to originate from the NAT-portion instead of the originator of the IP-packet. NAT can be implemented in a variety of schemes of translating addresses and/or port numbers, with each type of NAT-scheme affecting application communication protocols differently. For example, NAT-types include full-cone NAT (also known as one-to-one NAT), address-restricted cone NAT, port-restricted cone NAT and symmetric NAT.

0041Firewalls can be implemented in hardware, software or a combination of both. Firewalls are frequently used to prevent unauthorized Internet users from accessing private networks, such as intranets, that are connected to the Internet <b>175</b>. The NAT/Firewall <b>172</b> is configured to permit or deny network transmissions based upon a set of rules and other criteria. All messages entering or leaving the intranet pass through the firewall, which inspects each message and blocks those that do not meet the specified security criteria.

0042Firewalls often have functionality to protect hosts behind the network by implementing network address translation (NAT) functionality. The firewall provides private addresses as defined in RFC 1918 to the hosts protected behind a firewall. Once a pass through connection is opened through the firewall, NAT translation association for the data session is often released within a few seconds of data inactivity for the session. Thus, the NAT/Firewall <b>172</b> is used to collectively refer to the hardware and/or software that performs the firewall and NAT functions for a particular intranet.

0043Referring to <figref idref="DRAWINGS">FIG. 2A</figref>, when the UE <b>200</b> executes a client-application that interacts with an application being hosted by the application server <b>170</b>, which is external to (i.e., not behind) the core network <b>126</b>A, it will be appreciated that this interaction must typically comply with the NAT and/or firewall rules or settings of the core network <b>126</b>A as enforced by the NAT/Firewall <b>172</b>. For example, as will be described in greater detail below, dormant or idle connections between the UE <b>200</b> and the application server <b>170</b> may be shut down by the NAT/Firewall <b>172</b>, such that when the application server <b>170</b> attempts to send data to the UE <b>200</b> the connection requires re-establishment. The UE <b>200</b> can mitigate this problem somewhat by sending periodic keep-alive packets over this connection during dormant or idle periods so that the NAT/Firewall <b>172</b> detects activity on the connection and refrains from shutting the connection down. However, it will be appreciated that transmitting ‘dummy’ packets in this manner drains battery life on the UE <b>200</b>.

0044<figref idref="DRAWINGS">FIG. 2B</figref> illustrates the carrier network <b>126</b> of <figref idref="DRAWINGS">FIG. 1</figref> according to another embodiment of the present invention. In particular, <figref idref="DRAWINGS">FIG. 2B</figref> denotes the core network or packet core <b>126</b> as <b>126</b>B, whereby the core network <b>126</b>B corresponds to an EV-DO core network. Accordingly, because <figref idref="DRAWINGS">FIG. 2B</figref> is specific to EV-DO systems instead of W-CDMA as in <figref idref="DRAWINGS">FIG. 2A</figref>, the mobile stations in <figref idref="DRAWINGS">FIG. 2B</figref> are described as ATs instead of UEs, and so on.

0045In the embodiment of <figref idref="DRAWINGS">FIG. 2B</figref>, the core network <b>126</b>B includes a packet data serving node (PDSN) <b>161</b>, a broadcast serving node (BSN) <b>163</b> and the NAT/Firewall <b>172</b>. Similar to the core network <b>126</b>A of <figref idref="DRAWINGS">FIG. 2A</figref>, the components of the core network <b>126</b>B are connected to an external data packet network (or Internet) <b>175</b>, and through the Internet <b>175</b> are further connected to the application server <b>170</b>. However, it is appreciated that portions of the Internet <b>175</b> and/or other components may be located inside of the core network <b>126</b>B in alternative embodiments.

0046Referring to <figref idref="DRAWINGS">FIG. 2B</figref>, the PDSN <b>161</b> provides access to the Internet <b>175</b>, intranets and/or remote servers (e.g., application server <b>170</b>) for mobile stations (e.g., access terminals, such as <b>102</b>, <b>108</b>, <b>110</b>, <b>112</b> from <figref idref="DRAWINGS">FIG. 1</figref>) utilizing, for example, a CDMA2000 Radio Access Network (RAN) (e.g., RAN <b>120</b> of <figref idref="DRAWINGS">FIG. 1</figref>). Acting as an access gateway, the PDSN <b>161</b> may provide simple IP and mobile IP access, foreign agent support, and packet transport. The PDSN <b>161</b> can act as a client for Authentication, Authorization, and Accounting (AAA) servers and other supporting infrastructure and provides mobile stations with a gateway to the IP network as is known in the art. As shown in <figref idref="DRAWINGS">FIG. 2B</figref>, the PDSN <b>161</b> may communicate with the RAN <b>120</b> (e.g., the BSC/RNC <b>122</b>) via a conventional A<b>10</b> connection. The A<b>10</b> connection is well-known in the art and will not be described further for the sake of brevity.

0047Referring to <figref idref="DRAWINGS">FIG. 2B</figref>, the broadcast serving node (BSN) <b>163</b> may be configured to support multicast and broadcast services. The BSN <b>163</b> communicates with the RAN <b>120</b> (e.g., the BSC/RNC <b>122</b>) via a broadcast (BC) A<b>10</b> connection, and with the application server <b>170</b> via the Internet <b>175</b>. The BCA<b>10</b> connection is used to transfer multicast and/or broadcast messaging. Accordingly, the application server <b>170</b> sends unicast messaging to the PDSN <b>161</b> via the Internet <b>175</b>, and sends multicast messaging to the BSN <b>163</b> via the Internet <b>175</b>. Generally, the RAN <b>120</b> can transmit multicast messages, received from the BSN <b>163</b> via the BCA<b>10</b> connection, over a broadcast channel (BCH) of the air interface <b>104</b> to one or more access terminals <b>200</b>.

0048Referring to <figref idref="DRAWINGS">FIG. 2B</figref>, similar to <figref idref="DRAWINGS">FIG. 2A</figref>, the NAT/Firewall <b>172</b> is positioned between the PDSN <b>161</b> and/or BSN <b>163</b> and the Internet <b>175</b>. The NAT/Firewall <b>172</b> may be co-located with the PDSN <b>161</b> or may be logically implemented as a part of the PDSN <b>161</b>. The NAT/Firewall <b>172</b> separates the core network <b>126</b>B from the Internet <b>175</b> and/or other core networks. For example, the NAT/Firewall <b>172</b> may perform NAT functionality such that network address information in datagram (IP) packet headers that traverse the NAT-portion are modified such that outgoing Internet Protocol (IP) packets appear to originate from the NAT-portion instead of the originator of the IP-packet. NAT can be implemented in a variety of schemes of translating addresses and/or port numbers, with each type of NAT-scheme affecting application communication protocols differently. For example, NAT-types include full-cone NAT (also known as one-to-one NAT), address-restricted cone NAT, port-restricted cone NAT and symmetric NAT.

0049Hereinafter, references to components within the wireless communications system <b>100</b> will for the most part be given with respect to W-CDMA-specific terminology for the sake of consistency, such as Node B, UE, RNC, GGSN, SSGN, etc. However, it will be appreciated that any of the figures described below can be implemented within the W-CDMA infrastructure (e.g., as in <figref idref="DRAWINGS">FIG. 2A</figref>), EV-DO infrastructure (e.g., as in <figref idref="DRAWINGS">FIG. 2B</figref>) and/or in accordance with infrastructure that conforms with other communication protocols.

0050<figref idref="DRAWINGS">FIG. 2C</figref> illustrates an example of the wireless communications system <b>100</b> of <figref idref="DRAWINGS">FIG. 1</figref> in more detail. In particular, referring to <figref idref="DRAWINGS">FIG. 2C</figref>, UEs <b>1</b> . . . N are shown as connecting to the RAN <b>120</b> at locations serviced by different packet data network end-points. The illustration of <figref idref="DRAWINGS">FIG. 2C</figref> is specific to W-CDMA systems and terminology, although it will be appreciated how <figref idref="DRAWINGS">FIG. 2C</figref> could be modified to conform with a lx EV-DO system. Accordingly, UEs <b>1</b> and <b>3</b> connect to the RAN <b>120</b> at a portion served by a first packet data network end-point (or core network) <b>162</b> (e.g., which may correspond to SGSN, GGSN, PDSN, a home agent (HA), a foreign agent (FA), etc.). The first packet data network end-point <b>162</b> in turn connects, via the routing unit <b>188</b>, to the Internet <b>175</b> and/or to one or more of an authentication, authorization and accounting (AAA) server <b>182</b>, a provisioning server <b>184</b>, an Internet Protocol (IP) Multimedia Subsystem (IMS)/Session Initiation Protocol (SIP) Registration Server <b>186</b> and/or the application server <b>170</b>. UEs <b>2</b> and <b>5</b> . . . N connect to the RAN <b>120</b> at a portion served by a second packet data network end-point <b>164</b> (e.g., which may correspond to SGSN, GGSN, PDSN, FA, HA, etc.). Similar to the first packet data network end-point <b>162</b>, the second packet data network end-point <b>164</b> in turn connects, via the routing unit <b>188</b>, to the Internet <b>175</b> and/or to one or more of the AAA server <b>182</b>, a provisioning server <b>184</b>, an IMS/SIP Registration Server <b>186</b> and/or the application server <b>170</b>. UE <b>4</b> connects directly to the Internet <b>175</b>, and through the Internet <b>175</b> can then connect to any of the system components described above.

0051While not shown explicitly in <figref idref="DRAWINGS">FIG. 2C</figref>, it will be appreciated that one or more NAT/Firewalls <b>172</b> can be positioned between the packet data network end-points <b>162</b> and <b>164</b> and the Internet <b>175</b> and/or the servers <b>170</b>, <b>182</b>, <b>184</b> and/or <b>186</b>. Also, referring to <figref idref="DRAWINGS">FIG. 2C</figref>, UEs <b>1</b>, <b>3</b> and <b>5</b> . . . N are illustrated as wireless cell-phones, UE <b>2</b> is illustrated as a wireless tablet-PC and UE <b>4</b> is illustrated as a wired desktop station. However, in other embodiments, it will be appreciated that the wireless communication system <b>100</b> can connect to any type of UE, and the examples illustrated in <figref idref="DRAWINGS">FIG. 2C</figref> are not intended to limit the types of UEs that may be implemented within the system. Also, while the AAA server <b>182</b>, the provisioning server <b>184</b>, the IMS/SIP registration server <b>186</b> and the application server <b>170</b> are each illustrated as structurally separate servers, one or more of these servers may be consolidated in at least one embodiment of the invention.

0052Further, referring to <figref idref="DRAWINGS">FIG. 2C</figref>, the application server <b>170</b> is illustrated as including a plurality of media control complexes (MCCs) <b>1</b> . . . N <b>170</b>B, and a plurality of regional dispatchers <b>1</b> . . . N <b>170</b>A. Collectively, the regional dispatchers <b>170</b>A and MCCs <b>170</b>B are included within the application server <b>170</b>, which in at least one embodiment can correspond to a distributed network of servers that collectively functions to arbitrate communication sessions (e.g., half-duplex group communication sessions via IP unicasting and/or IP multicasting protocols) within the wireless communication system <b>100</b>. For example, because the communication sessions arbitrated by the application server <b>170</b> can theoretically take place between UEs located anywhere within the system <b>100</b>, multiple regional dispatchers <b>170</b>A and MCCs are distributed to reduce latency for the arbitrated communication sessions (e.g., so that a MCC in North America is not relaying media back-and-forth between session participants located in China). Thus, when reference is made to the application server <b>170</b>, it will be appreciated that the associated functionality can be enforced by one or more of the regional dispatchers <b>170</b>A and/or one or more of the MCCs <b>170</b>B. The regional dispatchers <b>170</b>A are generally responsible for any functionality related to establishing a communication session (e.g., handling signaling messages between the UEs, scheduling and/or sending announce messages, etc.), whereas the MCCs <b>170</b>B are responsible for hosting the communication session for the duration of the call instance, including conducting an in-call signaling and an actual exchange of media during an arbitrated communication session.

0053Referring to <figref idref="DRAWINGS">FIG. 3</figref>, a UE <b>200</b>, (here a wireless device), such as a cellular telephone, has a platform <b>202</b> that can receive and execute software applications, data and/or commands transmitted from the RAN <b>120</b> that may ultimately come from the core network <b>126</b>, the Internet and/or other remote servers and networks. The platform <b>202</b> can include a transceiver <b>206</b> operably coupled to an application specific integrated circuit (ASIC) <b>208</b>, or other processor, microprocessor, logic circuit, or other data processing device. The ASIC <b>208</b> or other processor executes the application programming interface (API) <b>210</b> layer that interfaces with any resident programs in the memory <b>212</b> of the wireless device. The memory <b>212</b> can be comprised of read-only or random-access memory (RAM and ROM), EEPROM, flash cards, or any memory common to computer platforms. The platform <b>202</b> also can include a local database <b>214</b> that can hold applications not actively used in memory <b>212</b>. The local database <b>214</b> is typically a flash memory cell, but can be any secondary storage device as known in the art, such as magnetic media, EEPROM, optical media, tape, soft or hard disk, or the like. The internal platform <b>202</b> components can also be operably coupled to external devices such as antenna <b>222</b>, display <b>224</b>, push-to-talk button <b>228</b> and keypad <b>226</b> among other components, as is known in the art.

0054Accordingly, an embodiment of the invention can include a UE including the ability to perform the functions described herein. As will be appreciated by those skilled in the art, the various logic elements can be embodied in discrete elements, software modules executed on a processor or any combination of software and hardware to achieve the functionality disclosed herein. For example, ASIC <b>208</b>, memory <b>212</b>, API <b>210</b> and local database <b>214</b> may all be used cooperatively to load, store and execute the various functions disclosed herein and thus the logic to perform these functions may be distributed over various elements. Alternatively, the functionality could be incorporated into one discrete component. Therefore, the features of the UE <b>200</b> in <figref idref="DRAWINGS">FIG. 3</figref> are to be considered merely illustrative and the invention is not limited to the illustrated features or arrangement.

0055The wireless communication between the UE <b>102</b> or <b>200</b> and the RAN <b>120</b> can be based on different technologies, such as code division multiple access (CDMA), W-CDMA, time division multiple access (TDMA), frequency division multiple access (FDMA), Orthogonal Frequency Division Multiplexing (OFDM), the Global System for Mobile Communications (GSM), or other protocols that may be used in a wireless communications network or a data communications network. For example, in W-CDMA, the data communication is typically between the client device <b>102</b>, Node B(s) <b>124</b>, and the RNC <b>122</b>. The RNC <b>122</b> can be connected to multiple data networks such as the core network <b>126</b>, PSTN, the Internet, a virtual private network, a SGSN, a GGSN and the like, thus allowing the UE <b>102</b> or <b>200</b> access to a broader communication network. As discussed in the foregoing and known in the art, voice transmission and/or data can be transmitted to the UEs from the RAN using a variety of networks and configurations. Accordingly, the illustrations provided herein are not intended to limit the embodiments of the invention and are merely to aid in the description of aspects of embodiments of the invention.

0056As will be appreciated by one of ordinary skill in the art, a given UE can be configured to execute a plurality of client applications that are each configured for interaction with an application server, such as the application server <b>170</b>. The application server <b>170</b> at least partially supports one or more of the plurality of client applications. For example, if the client application is a PTT client, the application server <b>170</b> can be responsible for setting up and arbitrating PTT sessions with one or more other UEs.

0057Accordingly, the application server <b>170</b> is expected to be able to send data to target UEs (i.e., mobile-terminated data) relatively quickly. If these target UEs are served by a core network that includes a NAT/Firewall (i.e., an ‘internal’ network that is separated by the NAT/Firewall from ‘external’ networks), as shown in <figref idref="DRAWINGS">FIGS. 2A and 2B</figref> for example, the mobile-terminated data from the application server <b>170</b> is required to traverse the NAT/Firewall <b>172</b> in the core network(s) of the UEs. In this case, it is typical for the client applications to implement NAT traversal technique(s) to detect the IP and port translation by the NAT/Firewall <b>172</b> and to use a keep-alive mechanism so as to maintain the NAT state. Similarly, to maintain the firewall state with the NAT/Firewall <b>172</b>, the client applications on the target UEs are required to transmit periodic keep-alive packets to the application server <b>170</b>, through the NAT/Firewall <b>172</b>.

0058It will be appreciated that each client application on the given UE can potentially be required to send the keep-alive packets to one or more application servers to maintain their respective states with the NAT/Firewall <b>172</b>. This means that the given UE will periodically wake up, set-up a traffic channel (TCH) with the RAN <b>120</b>, transmit the keep-alive packet and then go back to sleep. As the number of client applications that are attempting to maintain their states with the NAT/Firewall <b>172</b> increases, the given UE will consume more and more power, which reduces battery life.

0059<figref idref="DRAWINGS">FIG. 4</figref> illustrates an example of routing of keep-alive packets from a plurality of UEs in a core network. As shown in <figref idref="DRAWINGS">FIG. 4</figref>, UEs <b>200</b>A and <b>200</b>B each send keep-alive packets over a wireless link or air interface to a serving NodeB (or base station) <b>124</b>, which then forwards the keep-alive packets to a serving RNC (or BSC) <b>122</b>, which in turn sends the keep-alive packets to the packet data network end-point <b>162</b> (e.g., the GGSN or PDSN) and then the NAT/Firewall <b>172</b>. The NAT/Firewall <b>172</b> performs a translation function on the keep-alive packets and forwards the packets to the Internet <b>175</b>. Eventually, the keep-alive packets arrive at the application server <b>170</b> and are discarded because the function of the keep-alive packets is to maintain the respective NAT and firewall states of one or more client applications of the UEs <b>200</b>A and <b>200</b>B with the NAT/Firewall <b>172</b>. Due to the traffic associated with the keep-alive packets from UEs <b>200</b>A and <b>200</b>B, the respective NAT and firewall states of the one or more client applications of the UEs <b>200</b>A and <b>200</b>B are maintained by the NAT/Firewall <b>172</b>, as will be described in more detail below. In <figref idref="DRAWINGS">FIG. 4</figref>, the respective routing paths of the keep-alive packets for UEs <b>200</b>A and <b>200</b>B are illustrated as routing path <b>400</b>A and routing path <b>400</b>B, respectively.

0060<figref idref="DRAWINGS">FIG. 5A</figref> illustrates a process by which the application server <b>170</b> sends mobile-terminated data to a plurality of client applications <b>1</b> . . . N on a given UE. Referring to <figref idref="DRAWINGS">FIG. 5A</figref>, the application server <b>170</b> is described as supporting each of the plurality of client applications <b>1</b> . . . N. However, it will be appreciated that different client applications could be supported by different application servers in other implementations of <figref idref="DRAWINGS">FIG. 5A</figref>.

0061Referring to <figref idref="DRAWINGS">FIG. 5A</figref>, client application <b>1</b> of the given UE sets-up its NAT and firewall states with the NAT/Firewall <b>172</b>, and then registers with the application server <b>170</b>, <b>500</b>A. Client application <b>2</b> of the given UE also sets-up its NAT and firewall states with the NAT/Firewall <b>172</b>, and then registers with the application server <b>170</b>, <b>505</b>A. Client applications <b>3</b> . . . N of the given UE also each set-up their respective NAT and firewall states with the NAT/Firewall <b>172</b>, and each of client applications <b>3</b> . . . N then register with the application server <b>170</b>, <b>510</b>A. At this point, after <b>510</b>A of <figref idref="DRAWINGS">FIG. 5A</figref>, the application server <b>170</b> is capable of sending mobile-terminated data to the given UE for any of client applications <b>1</b> . . . N because each client application is registered and has active NAT and firewall states with the NAT/Firewall <b>172</b>.

0062As discussed above, the NAT/Firewall <b>172</b> does not maintain the NAT and firewall states for client applications <b>1</b> . . . N indefinitely. Rather, the NAT/Firewall <b>172</b> will eventually reset or disable the NAT and firewall states for one or more of the client applications <b>1</b> . . . N after a threshold period of inactivity. Accordingly, the NAT/Firewall <b>172</b> monitors traffic inactivity timers for each of the client applications <b>1</b> . . . N in <b>515</b>A. As will be appreciated, each traffic inactivity timer has an associated expiration period such that the NAT and/or firewall states for a particular client application are torn down upon expiration of the associated traffic inactivity timer.

0063Next, while the NAT and firewall states for client application <b>1</b> remain active, the application server <b>170</b> sends mobile-terminated data to the NAT/Firewall <b>172</b> for transmission to the given UE in association with client application <b>1</b>, <b>520</b>A. The NAT/Firewall <b>172</b> receives the mobile-terminated data, performs any necessary translation functions and then forwards the mobile-terminated data to the RAN <b>120</b> (e.g., via a SSGN/GGSN, via a PDSN, etc.) for transmission to the given UE, <b>525</b>A.

0064Next, while the NAT and firewall states for client application <b>2</b> remain active, the application server <b>170</b> sends mobile-terminated data to the NAT/Firewall <b>172</b> for transmission to the given UE in association with client application <b>2</b>, <b>530</b>A. The NAT/Firewall <b>172</b> receives the mobile-terminated data, performs any necessary translation functions and then forwards the mobile-terminated data to the RAN <b>120</b> (e.g., via a SSGN/GGSN, via a PDSN, etc.) for transmission to the given UE, <b>535</b>A.

0065Next, assume that the traffic inactivity timer(s) for client applications <b>3</b> . . . N expire at the NAT/Firewall <b>172</b>, <b>540</b>A, such that the NAT/Firewall <b>172</b> tears down the NAT and/or firewall states that were set-up for client applications <b>3</b> . . . N, <b>540</b>A. At this point, the NAT/Firewall <b>172</b> will no longer be able to forward IP packets to/from the given UE based on the NAT and/or firewall states that were set-up in <b>510</b>A and are now torn down.

0066Referring to <figref idref="DRAWINGS">FIG. 5A</figref>, after the NAT and firewall states for apps <b>3</b> . . . N are torn down in <b>540</b>A, assume that the application server <b>170</b> sends mobile-terminated data to the NAT/Firewall <b>172</b> for transmission to the given UE in association with client application <b>3</b>, <b>545</b>A. The NAT/Firewall <b>172</b> receives the mobile-terminated data, but the mobile-terminated data is not forwarded to the given UE because the NAT and/or firewall states for client application <b>3</b> are no longer active, <b>550</b>A.

0067<figref idref="DRAWINGS">FIG. 5B</figref> illustrates another process by which the application server <b>170</b> sends mobile-terminated data to a plurality of client applications <b>1</b> . . . N on the given UE. Referring to <b>5</b>B, as in <figref idref="DRAWINGS">FIG. 5A</figref>, the application server <b>170</b> is described as supporting each of the plurality of client applications <b>1</b> . . . N. However, it will be appreciated that different client applications could be supported by different application servers in other implementations of <figref idref="DRAWINGS">FIG. 5B</figref>.

0068Referring to <figref idref="DRAWINGS">FIG. 5B</figref>, <b>500</b>B through <b>515</b>B correspond to <b>500</b>A through <b>515</b>A, respectively, of <figref idref="DRAWINGS">FIG. 5A</figref> and as such will not be described further for the sake of brevity. After the NAT and firewall states for client applications <b>1</b> . . . N are set-up, the client applications each begin transmitting periodic keep-alive packets to the application server <b>170</b> (e.g., along routing paths <b>400</b>A/<b>400</b>B as shown in <figref idref="DRAWINGS">FIG. 4</figref>) so as to maintain the respective NAT and firewall states. Accordingly, after a given period of time that is no greater than the expiration period of the traffic interactivity timer(s), the given UE periodically wakes up, sets-up a traffic channel (TCH) with the RAN <b>120</b>, transmits a keep-alive packet for client application <b>1</b> to the application server <b>170</b> via the NAT/Firewall <b>172</b> and then goes back to sleep (at least, if the given UE is otherwise dormant or idle), <b>520</b>B. The NAT/Firewall <b>172</b> detects traffic in association with the NAT and/or firewall states for client application <b>1</b> and resets or restarts the traffic inactivity timer for client application <b>1</b>, <b>525</b>B.

0069The transmission of the keep-alive packet occurs in a similar manner in <b>530</b>B for client application <b>2</b> as in <b>520</b>B for client application <b>1</b>. Accordingly, the NAT/Firewall <b>172</b> detects traffic in association with the NAT and/or firewall states for client application <b>2</b> and resets or restarts the traffic inactivity timer for client application <b>2</b>, <b>535</b>B. Likewise, the transmission of the keep-alive packet occurs in a similar manner in <b>540</b>B for client applications <b>3</b> . . . N as in <b>520</b>B for client application <b>1</b> and/or <b>530</b>B for client application <b>2</b>. Accordingly, the NAT/Firewall <b>172</b> detects traffic in association with the NAT and/or firewall states for client applications <b>3</b> . . . N and resets or restarts the traffic inactivity timer(s) for client applications <b>3</b> . . . N, <b>545</b>B. While the keep-alive packets for client applications <b>1</b> . . . N are shown as separate transmissions that occur at <b>520</b>B, <b>530</b>B and <b>540</b>B, respectively, it will be appreciated that the given UE can attempt to coordinate the respective transmissions to make better use of system resources and/or battery life.

0070Next, each of the client applications <b>1</b> . . . N continues to send periodic keep-alive packets to the application server <b>170</b>, <b>550</b>B, and the NAT/Firewall <b>172</b> continues to reset the traffic inactivity timers for client applications <b>1</b> . . . N, <b>555</b>B, such that their respective NAT and/or firewall states are maintained. At some later point in time, the application server <b>170</b> sends mobile-terminated data to the NAT/Firewall <b>172</b> for transmission to the given UE in association with any of client applications <b>1</b> . . . N, <b>560</b>B. The NAT/Firewall <b>172</b> receives the mobile-terminated data, performs any necessary translation functions and then forwards the mobile-terminated data to the RAN <b>120</b> (e.g., via a SSGN/GGSN, via a PDSN, etc.) for transmission to the given UE, <b>565</b>B.

0071As will be appreciated from a review of <figref idref="DRAWINGS">FIGS. 5A and 5B</figref>, the given UE can conserve battery power by refraining from sending the periodic keep-alive packets as in <figref idref="DRAWINGS">FIG. 5A</figref>. However, this risks losing the NAT and/or firewall states with the NAT/Firewall <b>172</b> such that mobile-terminated data intended for a client application on the given UE will be lost. Alternatively, the given UE can transmit the keep-alive packets such that the NAT and/or firewall states are maintained as in <figref idref="DRAWINGS">FIG. 5B</figref>, albeit at the expense of increased power consumption at the given UE. Embodiments of the invention that will be described in more detail below are directed to a keep-alive packet transmission assistance mechanism whereby the given UE is ‘assisted’ by one or more other UEs in the same core network or packet core whereby the one or more other UEs send keep-alive packets on behalf of the given UE.

0072<figref idref="DRAWINGS">FIG. 6A</figref> illustrates a wireless communications system in accordance with an embodiment of the invention. <figref idref="DRAWINGS">FIG. 6A</figref> borrows certain components from FIGS. that were already described above, and any like-numbered components will not be described in further detail at this point for the sake of brevity.

0073Referring to <figref idref="DRAWINGS">FIG. 6A</figref>, a first packet core (<b>1</b>) and a second packet core (<b>2</b>) are illustrated. The packet core (<b>1</b>) includes the NAT/Firewall <b>172</b> as well as any network components that are ‘behind’ the NAT/Firewall <b>172</b>. Similarly, the packet core (<b>2</b>) includes another NAT/Firewall <b>172</b> as well as any network components that are ‘behind’ the other NAT/Firewall <b>172</b>. Thus, the term ‘packet core’ is generally used to refer to an internal network that can be reached by external devices or networks, such as the application server <b>170</b>, through a particular NAT/Firewall <b>172</b>. For example, the packet core (<b>1</b>) includes the NAT/Firewall <b>172</b>, the GGSN (or PDSN) <b>162</b> and the RAN <b>120</b> (which includes a Node B <b>124</b> and RNC <b>122</b>, or a BS <b>124</b> and BSC <b>122</b>). A plurality of UEs <b>200</b> can connect to the RAN <b>120</b> in the packet core (<b>1</b>). Similar infrastructure is included in the packet core (<b>2</b>) and will not be described further for the sake of brevity.

0074Referring to <figref idref="DRAWINGS">FIG. 6A</figref>, the packet core (<b>1</b>) further includes an assisting application server (AAS) <b>170</b>A. The AAS <b>170</b>A is a server that is configured to interact with the application server <b>170</b> and is coupled in some manner to the NAT/Firewall <b>172</b> within packet core (<b>1</b>). The coupling of the AAS <b>170</b>A to the packet core (<b>1</b>) can be achieved by maintaining a mapping of a particular AAS <b>170</b>A to the IP address of the packet core (<b>1</b>) elements, like the GGSN or the PDSN <b>162</b>, at the application server <b>170</b>. In an example, the AAS <b>170</b>A can correspond to a wireline device that need not have explicit wireless functionality, although in at least one embodiment the AAS <b>170</b>A could also be configured with its own wireless transceiver so as to conduct wireless communications.

0075The AAS <b>170</b>A is also coupled to one or more ‘assisting’ UEs <b>605</b>. The assisting UEs <b>605</b> are configured for wireless connectivity, and can connect to the RAN <b>120</b> within the packet core (<b>1</b>) in the same manner as the UEs <b>200</b>. In an embodiment, the assisting UEs <b>605</b> can be connected to a permanent power source so that their power consumption is not a critical issue. Alternatively, it is possible that one or more of the assisting UEs could be deployed as mobile devices that rely at least partially on battery power. In an alternative embodiment, multiple AAS <b>170</b>A can be deployed in a given packet core (<b>1</b>) when a relatively high number of client applications configured to receive keep alive-packet assistance are deployed in the given packet core (<b>1</b>). Similarly, the packet core (<b>2</b>) includes an AAS <b>170</b>B that is coupled to the NAT/Firewall <b>172</b> of the packet core (<b>2</b>) and is also coupled to one or more assisting UEs <b>610</b>. The AAS <b>170</b>B in the packet core (<b>2</b>) can be configured similar to the AAS <b>170</b>A in the packet core (<b>1</b>). The operation of the application server <b>170</b> with the AASs <b>170</b>A and <b>170</b>B as well the assisting UEs <b>605</b> and <b>610</b> will be described in more detail below with respect to <figref idref="DRAWINGS">FIGS. 7A through 7D</figref>.

0076<figref idref="DRAWINGS">FIG. 6B</figref> illustrates an example of routing of keep-alive packets from a plurality of UEs in the packet core (<b>1</b>) of <figref idref="DRAWINGS">FIG. 6A</figref> in accordance with an embodiment of the invention. As shown in <figref idref="DRAWINGS">FIG. 6B</figref>, UEs <b>200</b>A and <b>200</b>B are not actually responsible for sending their own keep-alive packets to the application server <b>170</b>. Rather, the application server <b>170</b> instructs the AAS <b>170</b>A to have one or more assisting UEs <b>605</b> send the keep-alive packets on behalf of UEs <b>200</b>A and <b>200</b>B. In an example, the application server <b>170</b> selects the AAS <b>170</b>A depending on the IP address of the packet core (<b>1</b>) provided by the UE <b>200</b>A and <b>200</b>B during the registration. The registration process of the UE <b>200</b>A and <b>200</b>B with the application server <b>170</b> also provides, to the application server <b>170</b>, the public IP address and the port as assigned by the NAT/Firewall <b>172</b> used for communication with the application server <b>170</b> through the NAT/Firewall <b>172</b>.

0077Referring to <figref idref="DRAWINGS">FIG. 6B</figref>, after selecting the AAS <b>170</b>A, the application server <b>170</b> provides the public IP address and the ports to the AAS <b>170</b>A for UE <b>200</b>A and <b>200</b>B. The AAS <b>170</b>A leverages or instructs the assisting UE(s) <b>605</b> to send keep-alive packets on behalf of UEs <b>200</b>A and <b>200</b>B over a wireless link or air interface to a serving NodeB (or base station) <b>124</b>, which then forwards the keep-alive packets to a serving RNC (or BSC) <b>122</b>, which in turn sends the keep-alive packets to the packet data network end-point (e.g., the GGSN or PDSN) <b>162</b> and then the NAT/Firewall <b>172</b>. The NAT/Firewall <b>172</b> performs a translation function on the keep-alive packets and forwards the packets to the Internet <b>175</b>. Eventually, the keep-alive packets arrive at the application server <b>170</b> and can be discarded because the function of the keep-alive packets is to maintain the respective NAT and firewall states of one or more client applications of the UEs <b>200</b>A and <b>200</b>B with the NAT/Firewall <b>172</b>.

0078As will be explained in greater detail below, in an embodiment, in order to ensure that the NAT state for the IP and Port of the UEs <b>200</b>A and <b>200</b>B is maintained, the assisting UE(s) <b>605</b> are configured to send keep-alive packets by replacing the source IP address of UE <b>605</b> with the source IP address of UEs <b>200</b>A and <b>200</b>B in the IP headers of the keep alive packets of the respective UEs sent to the application server <b>170</b>. Similarly, the source port of assisting UE(s) <b>605</b> are replaced with the source port used the UEs <b>200</b>A and <b>200</b>B in the UDP or the TCP headers of the keep alive packets. At the NAT/Firewall <b>172</b>, the source IP address, source port, destination IP address and destination port of the keep alive packets from the assisting UE(s) <b>605</b> ‘mimic’ the corresponding settings of packets sent from UE <b>200</b>A and <b>200</b>B, the NAT/Firewall <b>172</b> state for UEs <b>200</b>A and <b>200</b>B is maintained. Due to the traffic associated with the keep-alive packets from UEs <b>200</b>A and <b>200</b>B, the respective NAT and firewall states of the one or more client applications of the UEs <b>200</b>A and <b>200</b>B are maintained by the NAT/Firewall <b>172</b>.

0079In <figref idref="DRAWINGS">FIG. 6B</figref>, the respective routing paths of the keep-alive packets for UEs <b>200</b>A and <b>200</b>B are illustrated as routing path <b>600</b>A and <b>600</b>B, respectively. Unlike <figref idref="DRAWINGS">FIG. 4</figref>, it will be appreciated that the routing paths <b>600</b>A and <b>600</b>B originate from the assisting UE(s) <b>605</b> instead of the UEs <b>200</b>A and <b>200</b>B such that the power consumption of UEs <b>200</b>A and <b>200</b>B can be reduced while maintain their respective NAT and/or firewall states with the NAT/Firewall <b>172</b> of the packet core (<b>1</b>).

0080<figref idref="DRAWINGS">FIG. 7A</figref> illustrates a process by which the application server <b>170</b> sends mobile-terminated data to one or more client applications on a given UE (“UE <b>200</b>”) in accordance with an embodiment of the invention. <figref idref="DRAWINGS">FIG. 7A</figref> is described below with respect to the keep-alive packets that are sent in association with one particular client application. However, it will be appreciated how the process of <figref idref="DRAWINGS">FIG. 7A</figref> can scale to accommodate any number of client applications. Also, while <figref idref="DRAWINGS">FIG. 7A</figref> is generally described with references to components within packet core (<b>1</b>), it will be appreciated that the process of <figref idref="DRAWINGS">FIG. 7A</figref> can alternatively be implemented in any packet core or internal network that separated from external networks via the NAT/Firewall <b>172</b>.

0081Referring to <figref idref="DRAWINGS">FIG. 7A</figref>, a given client application on UE <b>200</b> establishes a packet data session with a packet data end point <b>162</b> (i.e., the PDSN or GGSN) of the packet core (<b>1</b>), <b>700</b>A. The given client application on UE <b>200</b> then obtains the IP address of the packet data end point <b>162</b> (i.e., the PDSN or GGSN) of the packet core (<b>1</b>), <b>701</b>A. The given client application on UE <b>200</b> sets-up its NAT and firewall states with the NAT/Firewall <b>172</b>, <b>702</b>A. For example, in setting-up the NAT and firewall states in <b>702</b>A, the given client application detects the NAT-portion of the NAT/Firewall <b>172</b>, establishes public and private port numbers and IP addresses to be used for the given client application and establishes a firewall association for the given client application.

0082As discussed above with respect to <figref idref="DRAWINGS">FIGS. 5A and 5B</figref>, the NAT/Firewall <b>172</b> does not maintain the NAT and firewall states for client applications <b>1</b> . . . N indefinitely. Rather, the NAT/Firewall <b>172</b> will eventually reset or disable the NAT and firewall states for one or more of the client applications <b>1</b> . . . N after a threshold period of inactivity. Accordingly, the NAT/Firewall <b>172</b> monitors a traffic inactivity timer for the given client application, <b>705</b>A. As will be appreciated, the traffic inactivity timer has an associated expiration period such that the NAT and/or firewall states for the given client application are torn down upon expiration of the associated traffic inactivity timer.

0083Referring to <figref idref="DRAWINGS">FIG. 7A</figref>, UE <b>200</b> registers the given client application with the application server <b>170</b>, <b>715</b>A. The registration of <b>715</b>A includes conveying, from UE <b>200</b> to the application server <b>170</b>, (i) the private IP address and port number for the given client application as established in <b>700</b>A, (ii) the public IP address and port number for the given client application as established in <b>702</b>A, and (iii) the IP address of the PDSN or GGSN, determined by UE <b>200</b> at <b>701</b>A. After registering the given client application with the application server <b>170</b> in <b>715</b>A, UE <b>200</b> does not send keep-alive packets to the application server <b>170</b> for maintaining the NAT and/or firewall states for the given client application with the NAT/Firewall <b>172</b>, <b>720</b>A. Unlike <figref idref="DRAWINGS">FIG. 5A</figref>, the reason UE <b>200</b> refrains from transmitting the keep-alive packets in <b>720</b>A is based on an expectation that the application server <b>170</b> will facilitate some other UE(s) in the same packet core (<b>1</b>) to transmit keep-alive packets on behalf of UE <b>200</b> so that the NAT and/or firewall states for UE <b>200</b> are maintained.

0084After the application server <b>170</b> completes registration of the given client application for UE <b>200</b>, the application server <b>170</b> selects an assisting application server (AAS) based on the IP address of the PDSN or GGSN that was reported by UE <b>200</b> to the application server <b>170</b> during the registration, <b>725</b>A. For example, the application server <b>170</b> can use the IP address of the PDSN or GGSN to identify an AAS that associates with the application server <b>170</b> and is also located in the same packet core as UE <b>200</b>, such as packet core (<b>1</b>). The application server <b>170</b> can then select the co-located AAS that is in the same packet core (<b>1</b>) as UE <b>200</b> in <b>725</b>A. As will be explained in more detail below, one or more of the assisting UE(s) <b>605</b> that are coupled to the selected AAS are expected to be capable of ‘masquerading’ as UE <b>200</b>, at least from the perspective of the NAT/Firewall <b>172</b> of the packet core (<b>1</b>).

0085After selecting the AAS <b>170</b>A based on the IP address of the PDSN or GGSN in <b>725</b>A, the application server <b>170</b> instructs the selected AAS to transmit keep-alive packets on behalf of the given client application of UE <b>200</b>, <b>730</b>A. In this case, the selected AAS corresponds to AAS <b>170</b>A within the packet core (<b>1</b>). The AAS <b>170</b>A receives the instructions from the application server <b>170</b> and then selects one or more of its coupled, assisting UEs <b>605</b> to be responsible for periodically transmitting keep-alive packets on behalf of the given client application of UE <b>200</b>, <b>735</b>A. For example, the selected assisting UE(s) <b>605</b> can correspond to UE(s) that are co-located with the AAS <b>170</b>A and are connected to the AAS <b>170</b>A via an interface like the USB or other similar interfaces. The AAS <b>170</b>A can communicate with the assisting UE(s) <b>605</b> over this interface instead of using the air interface to reduce contention for bandwidth and radio resources of the assisting UE(s) <b>605</b> while the assisting UE(s) <b>605</b> are sending keep alive packets. The AAS <b>170</b>A then instructs the selected assisting UE(s) <b>605</b> to begin transmitting keep-alive packets to the application server <b>170</b> on a periodic basis, <b>740</b>A. In an embodiment, the period for keep-alive packet repetition is established to be no greater than the expiration timer of the associated traffic inactivity timer (e.g., 15 seconds, 30 seconds, 1 minute, etc.) that is maintained at the NAT/Firewall <b>172</b>.

0086In <b>745</b>A, the selected assisting UE(s) <b>605</b> each configure a keep-alive packet in a manner that conforms with UE <b>200</b>, <b>745</b>A. This essentially means that the selected assisting UE(s) <b>605</b> are each masquerading as UE <b>200</b> so as to fool the NAT/Firewall <b>172</b> into interpreting the configured keep-alive packet from the selected UE(s) <b>605</b> as if the packet actually originated from UE <b>200</b>. For example, the public IP addresses and public port numbers and for UE <b>200</b> assigned by the NAT/Firewall <b>172</b> that were conveyed to the application server <b>170</b> can be passed to the AAS <b>170</b>A and then to the selected assisting UE(s) <b>605</b>. Instead of using their own IP address and port in the source IP and port fields of the IP headers of the keep-alive packet, the selected assisting UE(s) <b>605</b> can then use the public IP addresses and public port numbers for UE <b>200</b> in the IP (TCP/UDP) headers as the source IP address and port information to configure the keep-alive packet in <b>745</b>A for transmission to the application server <b>170</b>. Since the source IP address, destination IP address, source port and destination port combination used by the selected assisting UE(s) <b>605</b> within the keep-alive packet is associated with UE <b>200</b>, the NAT/Firewall <b>172</b> can interpret these packets as data traffic from UE <b>200</b> and thus can extend the associated NAT settings for the given client application of UE <b>200</b>.

0087After configuring the keep-alive packet in <b>745</b>A, the selected assisting UE(s) <b>605</b> sets-up a TCH with the RAN <b>120</b> (if necessary), transmits the configured keep-alive packet to the application server <b>170</b> via the NAT/Firewall <b>172</b> and then (optionally) tears down the TCH, <b>750</b>A. The NAT/Firewall <b>172</b> detects the keep-alive packet from the selected assisting UE(s) <b>605</b> as traffic in association with the NAT and/or firewall states for the given client application and thereby resets or restarts the traffic inactivity timer for the given client application, <b>755</b>A. As will be appreciated, <b>745</b>A through <b>755</b>A can repeat any number of times such that the NAT and/or firewall states for the given client application on UE <b>200</b> can be maintained for an indefinite period of time. Similarly, <b>745</b>A through <b>755</b>A can repeat any number of times for one or more other UE(s) <b>200</b> whereby at least one assisting UE <b>605</b> can send keep alive packets on behalf of multiple UEs <b>200</b>. In other words, the process shown in <figref idref="DRAWINGS">FIG. 7A</figref> can be executed concurrently on behalf of a plurality of UEs and/or on behalf a plurality of a plurality of client applications for a given UE.

0088At some later point in time, while the NAT and firewall states for the given client application remain active, the application server <b>170</b> sends mobile-terminated data to the NAT/Firewall <b>172</b> for transmission to the given client application on UE <b>200</b>, <b>760</b>A. The NAT/Firewall <b>172</b> receives the mobile-terminated data, performs any necessary translation functions and then forwards the mobile-terminated data to the RAN <b>120</b> (e.g., via a SSGN/GGSN, via a PDSN, etc.) for transmission to UE <b>200</b>, <b>765</b>A.

0089<figref idref="DRAWINGS">FIG. 7B</figref> illustrates a continuation of the process of <figref idref="DRAWINGS">FIG. 7A</figref> in accordance with an embodiment of the invention. Referring to <figref idref="DRAWINGS">FIG. 7B</figref>, at some point after <b>765</b>A of <figref idref="DRAWINGS">FIG. 7A</figref>, assume that the given client application on UE <b>200</b> determines to de-register from the application server <b>170</b>. For example, a user of UE <b>200</b> may choose not to extend a service subscription associated with the given client application. In this case, UE <b>200</b> de-registers the given client application with the application server <b>170</b> in <b>700</b>B. Upon de-registering the given client application at the application server <b>170</b>, the application server <b>170</b> determines that the NAT and/or firewall states for the given client application need not be maintained by the NAT/Firewall <b>172</b>. Thus, the application server <b>170</b> instructs AAS <b>170</b>A to stop transmitting keep-alive packets on behalf of the given client application of UE <b>200</b>, <b>705</b>B. The AAS <b>170</b>A within the packet core (<b>1</b>) receives the instructions from the application server <b>170</b> and in turn instructs the selected assisting UE(s) <b>605</b> to stop transmitting the periodic keep-alive packets for UE <b>200</b>, <b>710</b>B. The selected assisting UE(s) <b>605</b> receives the instructions from the AAS <b>170</b>A and stops transmitting the periodic keep-alive packets for UE <b>200</b>, <b>715</b>B. However, it will be appreciated that the assisting UE(s) <b>605</b> may continue to transmit periodic keep alive packets for other client applications of UE <b>200</b> and/or for other UE(s) altogether. At some later point in time, the traffic inactivity timer(s) for the given client application expires at the NAT/Firewall <b>172</b>, <b>720</b>B, such that the NAT/Firewall <b>172</b> tears down the NAT and/or firewall states that were set-up for the given client application of UE <b>200</b>.

0090<figref idref="DRAWINGS">FIG. 7C</figref> illustrates a continuation of the process of <figref idref="DRAWINGS">FIG. 7A</figref> in accordance with another embodiment of the invention. Referring to <figref idref="DRAWINGS">FIG. 7C</figref>, at some point after <b>765</b>A of <figref idref="DRAWINGS">FIG. 7A</figref>, assume that the settings associated with the given client application are updated in some manner that affect the manner in which the keep-alive packets must be configured to result in a reset or restart of the associated traffic inactivity timer at the NAT/Firewall <b>172</b>, <b>700</b>C. In this embodiment, it will be further assumed that the causation of the update is not a handoff of UE <b>200</b> to a different packet core altogether, such that UE <b>200</b> remains in packet core (<b>1</b>) throughout the process of <figref idref="DRAWINGS">FIG. 7C</figref>. In an example, the IP address of the PDSN or GGSN may have changed, the private and/or public port numbers and/or IP address of the given client application may have changed and so on. Alternatively, the IP address assigned by the PDSN or the GGSN to the UE may have changed as a result of a re-negotiation of air interface and packet data session resources. As will be appreciated, any of the above noted events can trigger the update for the IP address and port mapping at the application server <b>170</b>.

0091After updating the settings in <b>700</b>C, UE <b>200</b> notifies the application server <b>170</b> with regard to the updated settings, <b>705</b>C. The application server <b>170</b> in turn notifies the AAS <b>170</b>A regarding the update, <b>710</b>C, and the AAS <b>170</b>A in turn notifies the selected assisting UE(s) <b>605</b> with regard to the update so that the selected assisting UE(s) <b>605</b> can modify the manner in which the periodically transmitted keep-alive packets are configured, <b>715</b>C.

0092In <b>720</b>C, the selected assisting UE(s) <b>605</b> configure a keep-alive packet in a manner that conforms with UE <b>200</b> in accordance with the updated setting-information. For example, if the updated setting-information corresponds to a change in the given client application's public IP address, then the selected assisting UE(s) <b>605</b> configure subsequent keep-alive packets with the updated public IP address in <b>720</b>C, and so on.

0093After configuring the keep-alive packet in <b>720</b>C, the selected assisting UE(s) <b>605</b> set-up a TCH with the RAN <b>120</b> (if necessary), transmit the configured keep-alive packet to the application server <b>170</b> via the NAT/Firewall <b>172</b> and then (optionally) tear down the TCH, <b>725</b>C. The NAT/Firewall <b>172</b> detects the keep-alive packet from the selected assisting UE(s) <b>605</b> as traffic in association with the NAT and/or firewall states for the given client application and thereby resets or restarts the traffic inactivity timer for the given client application, <b>730</b>C. As will be appreciated, <b>720</b>C through <b>730</b>C can repeat any number of times such that the NAT and/or firewall states for the given client application on UE <b>200</b> can be maintained for an indefinite period of time. Similarly, <b>720</b>C through <b>730</b>C can repeat any number of times for one or more other UE(s) <b>200</b> within packet core (<b>1</b>) whereby at least one assisting UE <b>605</b> is sending keep alive packets on behalf of multiple UEs <b>200</b>. In other words, the process shown in <figref idref="DRAWINGS">FIG. 7C</figref> can be executed concurrently on behalf of a plurality of UEs and/or on behalf of a plurality of client applications for a given UE.

0094<figref idref="DRAWINGS">FIG. 7D</figref> illustrates yet another continuation of the process of <figref idref="DRAWINGS">FIG. 7A</figref> in accordance with another embodiment of the invention. Referring to <figref idref="DRAWINGS">FIG. 7D</figref>, at some point after <b>765</b>A of <figref idref="DRAWINGS">FIG. 7A</figref>, assume that UE <b>200</b> hands off from packet core (<b>1</b>) to packet core (<b>2</b>), <b>700</b>D. For example, a handoff of UE <b>200</b> from one packet core to another can occur when UE <b>200</b> hands off from a first base station in a first subnet that is behind a first NAT/Firewall <b>172</b> to a second base station in a second subnet that is behind a second NAT/Firewall <b>172</b>. Similarly, a handoff of UE <b>200</b> from one packet core to another can occur when the UE <b>200</b> transitions from a first RNC (or BSC) on a first GGSN (or PDSN) <b>162</b> behind a first NAT/Firewall <b>172</b> in packet core (<b>1</b>) to a second RNC (or BSC) on a second GGSN (or PDSN) <b>162</b> behind a second NAT/Firewall <b>172</b> in a packet core (<b>2</b>).

0095While not shown explicitly in <figref idref="DRAWINGS">FIG. 7D</figref>, it will be appreciated the handoff of <b>700</b>D can include (i) obtaining the IP address of the PDSN or GGSN of packet core (<b>2</b>), (ii) setting up the NAT and firewall states with the NAT/Firewall <b>172</b> of packet core (<b>2</b>) and (iii) obtaining new private and public port numbers and IP addresses for UE <b>200</b> (if necessary). In other words, blocks <b>701</b>A, <b>702</b>A and <b>715</b>A of <figref idref="DRAWINGS">FIG. 7A</figref> can be performed at <b>700</b>D within packet core (<b>2</b>), if necessary.

0096After performing the handoff from packet core (<b>1</b>) to packet core (<b>2</b>), UE <b>200</b> notifies the application server <b>170</b> with regard to the new settings of UE <b>200</b> subsequent to the handoff (e.g., the IP address of the PDSN or GGSN in packet core (<b>2</b>), etc., as in <b>715</b>A of <figref idref="DRAWINGS">FIG. 7A</figref>), <b>705</b>D. Also, after performing the handoff, the NAT/Firewall <b>172</b> in the packet core (<b>2</b>) begins to monitor a traffic inactivity timer for the given client application, <b>710</b>D. As will be appreciated, the traffic inactivity timer has an associated expiration period such that the NAT and/or firewall states for the given client application are torn down upon expiration of the associated traffic inactivity timer.

0097After the application server <b>170</b> is notified of the handoff of UE <b>200</b> from packet core (<b>1</b>) to packet core (<b>2</b>), the application server <b>170</b> determines that the NAT and firewall states no longer need to be maintained for the given client application in packet core (<b>1</b>). Accordingly, the application server <b>170</b> instructs AAS <b>170</b>A to stop transmitting keep-alive packets on behalf of the given client application of UE <b>200</b>, <b>715</b>D. The AAS <b>170</b>A within the packet core (<b>1</b>) receives the instructions from the application server <b>170</b> and in turn instructs the selected assisting UE(s) <b>605</b> in packet core (<b>1</b>) to stop transmitting the periodic keep-alive packets for UE <b>200</b>, <b>720</b>D. The selected assisting UE(s) <b>605</b> receive the instructions from the AAS <b>170</b>A and stop transmitting the periodic keep-alive packets, <b>725</b>D. However, if necessary, the assisting UE(s) <b>605</b> in packet core (<b>1</b>) can continue to send keep alive messages for other UE(s) that are still associated with packet core (<b>1</b>).

0098Also, after the application server <b>170</b> is notified of the handoff of UE <b>200</b> from packet core (<b>1</b>) to packet core (<b>2</b>), the application server <b>170</b> selects an assisting application server (AAS) in packet core (<b>2</b>) based on the IP address of the PDSN or GGSN that was reported by UE <b>200</b> to the application server <b>170</b> in <b>705</b>D, <b>730</b>D. For example, the application server <b>170</b> can use the IP address of the PDSN or GGSN in packet core (<b>2</b>) to identify an AAS that associates with the application server <b>170</b> and is also located in the same packet core (<b>2</b>) as UE <b>200</b>. The application server <b>170</b> can then select the co-located AAS (i.e., AAS <b>170</b>B) in the same packet core (<b>2</b>) as UE <b>200</b> in <b>730</b>D.

0099After selecting the AAS <b>170</b>B based on the IP address of the PDSN or GGSN in the packet core (<b>2</b>) in <b>730</b>D, the application server <b>170</b> instructs the selected AAS (i.e., AAS <b>170</b>B) to transmit keep-alive packets on behalf of the given client application of UE <b>200</b>, <b>735</b>D. In this case, the selected AAS corresponds to AAS <b>170</b>B within the packet core (<b>2</b>).

0100Also, at some point in time, the traffic inactivity timer for the given client application expires at the NAT/Firewall <b>172</b> of packet core (<b>1</b>), <b>740</b>D, due to the cessation of keep-alive packet transmissions by the selected assisting UE(s) <b>605</b> in packet core (<b>1</b>) in <b>725</b>D. Accordingly, in <b>740</b>D, assume that this traffic inactivity timer expires, and that the NAT/Firewall <b>172</b> in packet core (<b>1</b>) tears down the NAT and/or firewall states that were set-up for the given client application of UE <b>200</b>.

0101The AAS <b>170</b>B receives the instructions from the application server <b>170</b> and then selects one or more of its coupled, assisting UEs <b>610</b> in packet core (<b>2</b>) to be responsible for periodically transmitting keep-alive packets on behalf of the given client application of UE <b>200</b> in packet core (<b>2</b>), <b>745</b>D. The AAS <b>170</b>B then instructs the selected UE(s) <b>610</b> to begin transmitting keep-alive packets to the application server <b>170</b> on a periodic basis, <b>745</b>D. In an embodiment, the transmission interval or period for keep-alive packet repetition is established to be no greater than the expiration period of the associated traffic inactivity timer (e.g., 30 seconds, 1 minute, etc.) that is maintained at the NAT/Firewall <b>172</b> in the packet core (<b>2</b>).

0102In <b>750</b>D, the selected assisting UE(s) <b>610</b> configure a keep-alive packet in a manner that conforms with UE <b>200</b> in the packet core (<b>2</b>) (e.g., see similar to <b>745</b>A of <figref idref="DRAWINGS">FIG. 7A</figref>). After configuring the keep-alive packet in <b>750</b>D, the selected assisting UE(s) <b>610</b> set-up a TCH with the RAN <b>120</b> (if necessary), transmit the configured keep-alive packet to the application server <b>170</b> via the NAT/Firewall <b>172</b> and then (optionally) tear down the TCH, <b>755</b>D. The NAT/Firewall <b>172</b> of the packet core (<b>2</b>) detects the keep-alive packet from the selected assisting UE(s) <b>610</b> as traffic in association with the NAT and/or firewall states for the given client application and thereby resets or restarts the traffic inactivity timer for the given client application, <b>760</b>D. As will be appreciated, <b>750</b>D through <b>760</b>D can repeat any number of times such that the NAT and/or firewall states for the given client application on UE <b>200</b> can be maintained for an indefinite period of time in packet core (<b>2</b>). Similarly, <b>750</b>D through <b>760</b>D can repeat any number of times to maintain NAT and/or firewall states for one or more other client applications on the same UE <b>200</b> and/or one or more other UEs altogether.

0103At some later point in time, while the NAT and firewall states for the given client application remain active in packet core (<b>2</b>), the application server <b>170</b> sends mobile-terminated data to the NAT/Firewall <b>172</b> in packet core (<b>2</b>) for transmission to the given client application on UE <b>200</b>, <b>765</b>D. The NAT/Firewall <b>172</b> in packet core (<b>2</b>) receives the mobile-terminated data, performs any necessary translation functions and then forwards the mobile-terminated data to the RAN <b>120</b> (e.g., via a SSGN/GGSN, via a PDSN, etc.) for transmission to UE <b>200</b>, <b>770</b>D.

0104Those of skill in the art will appreciate that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

0105Further, those of skill in the art will appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

0106The various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

0107The methods, sequences and/or algorithms described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal (e.g., UE). In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

0108In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

0109While the foregoing disclosure shows illustrative embodiments of the invention, it should be noted that various changes and modifications could be made herein without departing from the scope of the invention as defined by the appended claims. The functions, steps and/or actions of the method claims in accordance with the embodiments of the invention described herein need not be performed in any particular order. Furthermore, although elements of the invention may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated.