WO2013135913A2

WO2013135913A2 - Caching in a communication system

Info

Publication number: WO2013135913A2
Application number: PCT/EP2013/059862
Authority: WO
Inventors: Mikko Tapani SUNI
Original assignee: Nokia Siemens Networks Oy
Priority date: 2012-03-16
Filing date: 2013-05-14
Publication date: 2013-09-19
Also published as: WO2013135913A8; WO2013135913A3

Abstract

Caching in a communication system A method, comprising: determining a mobility event associated with a mobile device with a function with a coherent state; and informing the coherent function of the mobility event.

Description

DESCRIPTION

TITLE

Caching in a communication system

This disclosure relates to caching in a communication system.

A communication system can be seen as a facility that enables communication of data and other signals between two or more entities such as fixed or mobile communication devices, base stations, servers, machine type communication devices and/or other communication nodes. A communication system and compatible communicating entities typically operate in accordance with a given standard or specification which sets out what the various entities associated with the system are permitted to do and how that should be achieved. For example, the standards, specifications and related protocols can define the manner how various aspects of communication such as access to the communication system, communication of user and signalling information and various messaging aspects shall be implemented between communicating entities.

Data communications can be carried on wired or wireless carriers. In wired or fixed line systems, communications take place between entities that are connected via wires. In a wireless system at least a part of communications between stations occurs over radio or other wireless links. A feature of the wireless systems is that they offer mobility for the users thereof, hence the name mobile systems. Examples of wireless systems include public land mobile networks (PLMN) such as cellular networks, satellite based communication systems and different wireless local networks, for example wireless local area networks (WLAN). A wireless system can be divided into cells or other radio coverage or service areas provided by a station and users thereof may move from a cell to the other.

Byte caching is a technology aiming to reduce the amount of data communicated on wide area network (WAN) links in fixed data networks. Byte caching is typically operated on transport control protocol (TCP) layer. The byte caching functions by looking for repetitive bit patterns on TCP payload stream. Byte caching needs to be deployed at both ends of a transmission link. Once a byte caching function recognizes a repetitive bit pattern a token can be associated with the pattern based on an agreement between the ends. Once the token is agreed, the transmitting end can replace the original data with the token. The receiving end can then reproduce the traffic packets/stream by fetching the original content from a local cache using the token as a key.

The prior art byte caching is operated on point-to-point links. No consideration has been given to operation in association with data communication over wireless links and/or with mobile users.

Some embodiments may address one or several of the above issues.

There is provided according to a first aspect a method, comprising: determining a mobility event associated with a mobile device with a function with a coherent state; and informing the coherent function of the mobility event.

The function with a coherent state may comprise at least one of a caching function and a compression and/or decompression algorithm.

The coherent function may provide byte caching.

The coherent function may be provided between a first endpoint in a packet core network and a second endpoint in a radio network.

The second endpoint may be provided in radio access network.

The second endpoint may be provided in at least one of a breakout application server, a radio network controller, and a base station.

The method may comprise communicating information of the mobility event to a communicated to the second endpoint.

The method may comprise informing by the second endpoint to the first endpoint of the mobility event.

The method may comprise communicating said information on a lu, Gn, or S1 -U interface.

The method may comprise transferring at least one caching function endpoint another location in response to the mobility event.

The mobility event may comprise at least one of a handover of the mobile device and relocation of the mobile device from a first radio system to a second radio access network.

A computer program comprising program code may, when run, cause the method to be performed.

There is provided according to a second aspect a method, comprising: operating a function with a coherent state for a mobile device; receiving information regarding a mobility event associated with the mobile device; and disabling the coherent function in response to the information. The function with a coherent state may comprise at least one of a caching function and a compression and/or decompression algorithm.

The coherent function may provide byte caching.

The second endpoint may be provided in radio access network.

A computer program comprising program code may, when run, cause the method be performed.

There is provided according to a third aspect a method, comprising: initiating a new instance of an operational function with a coherent state associated with a mobile device in response to an indication in response to a mobility event associated with the mobile device; and operating the coherent function for the mobile device from the new instance.

The coherent function may provide byte caching.

The second endpoint may be provided in radio access network.

The second endpoint may be provided in at least one of a breakout application server, a radio network controller, and a base station. The method may comprise communicating information of the mobility event to a communicated to the second endpoint.

There is provided according to a fourth aspect an apparatus comprising at least one processor and at least one memory including computer program code the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: determine a mobility event associated with a mobile device with a function with a coherent state, and inform the coherent function of the mobility event.

The coherent function may provide byte caching.

The apparatus may be further configured to perform: communicating information of the mobility event to a communicated to the second endpoint.

The apparatus may be further configured to perform: informing by the second endpoint to the first endpoint of the mobility event.

The apparatus may be further configured to perform communicating said information on a lu, Gn, or S1-U interface.

The apparatus may be further configured to perform transferring at least one caching function endpoint another location in response to the mobility event.

The mobility event may comprise at least one of a handover of the mobile device and relocation of the mobile device from a first radio system to a second radio access network. There is provided according to a fifth aspect an apparatus comprising at least one processor and at least one memory including computer program code the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: provide a function with a coherent state for a mobile device, receive information regarding a mobility event associated with the mobile device, and disable the coherent function in response to the information.

The coherent function may provide byte caching.

The coherent function may be provide between a first endpoint in a packet core network and a second endpoint in a radio network.

There is provided according to a sixth aspect an apparatus comprising at least one processor and at least one memory including computer program code the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: cause initiation of a new instance of an operational function with a coherent state associated with a mobile device in response to an indication generated in response to a mobility event associated with the mobile device, and provide the coherent function for the mobile device from the new instance.

The coherent function may provide byte caching.

The coherent function may be provided between a first endpoint in a packet core network and a second endpoint in a radio network. The apparatus may be further configured to perform: communicating information of the mobility event to a communicated to the second endpoint.

There is provided according to a seventh aspect an apparatus, comprising: means for determining a mobility event associated with a mobile device with a function with a coherent state; and means for informing the coherent function of the mobility event.

The coherent function may provide byte caching.

The second endpoint may be provided in radio access network.

The apparatus may comprise means for communicating information of the mobility event to a communicated to the second endpoint.

The apparatus may comprise means for informing by the second endpoint to the first endpoint of the mobility event.

The apparatus may comprise means for communicating said information on a lu, Gn, or S1 -U interface.

The apparatus may comprise means for transferring at least one caching function endpoint another location in response to the mobility event.

The mobility event may comprise at least one of a handover of the mobile device and relocation of the mobile device from a first radio system to a second radio access network. There is provided according to an eights aspect an apparatus comprising: means for operating a function with a coherent state for a mobile device; means for receiving information regarding a mobility event associated with the mobile device; and means for disabling the coherent function in response to the information.

The coherent function may provide byte caching.

The second endpoint may be provided in radio access network.

There is provided according to a ninth aspect an apparatus comprising: means for initiating a new instance of an operational function with a coherent state associated with a mobile device in response to an indication in response to a mobility event associated with the mobile device; and means for operating the coherent function for the mobile device from the new instance.

The coherent function may provide byte caching.

The second endpoint may be provided in radio access network. The second endpoint may be provided in at least one of a breakout application server, a radio network controller, and a base station.

In accordance with an embodiment there is provided a method for caching, comprising determining a mobility event associated with a mobile device with a caching function, and informing the caching function of the mobility event.

In accordance with an embodiment there is provided a method for caching, comprising operating a caching function for a mobile device,

receiving information regarding a mobility event associated with the mobile device, and disabling the caching function in response to the information.

In accordance with an embodiment there is provided a method for caching, comprising initiating a new instance of an operational caching function associated with a mobile device in response to an indication in response to a mobility event associated with the mobile device, and operating the caching function for the mobile device from the new instance.

In accordance with an embodiment there is provided an apparatus configured to determine a mobility event associated with a mobile device with a caching function, and to inform the caching function of the mobility event.

In accordance with an embodiment there is provided an apparatus configured to provide a caching function for a mobile device, receive information regarding a mobility event associated with the mobile device, and disable the caching function in response to the information.

In accordance with an embodiment there is provided an apparatus configured to cause initiation of a new instance of an operational caching function associated with a mobile device in response to an indication generated in response to a mobility event associated with the mobile device, and to provide the caching function for the mobile device from the new instance.

The apparatus can comprise at least one processor and at least one memory including computer program code wherein the at least one memory and the computer program code are configured, with the at least one processor, to provide the various functions of the embodiments.

The caching function may provide byte caching.

The caching function may be provided between a first endpoint in a packet core network and a second endpoint in a radio network. The second endpoint may be located close to the radio interface.

The information of the mobility event may be communicated to the second endpoint. The second endpoint may inform the first endpoint of the mobility event.

The information may be communicated on a lu, Gn, or S1-U interface.

At least one caching function endpoint may be transferred to another location in response to the mobility event.

The mobility event may comprise handover of the mobile device.

The mobility event comprises relocation of the mobile device from a first radio system to a second radio system.

The first and/or second radio system may comprises eNB, NB, RNC, BSC, or I-

NodeB.

The apparatuses may be provided and the methods implemented in a node for a communication system.

A computer program comprising program code means adapted to perform the methods may also be provided.

Various other aspects and further embodiments are also described in the following detailed description of certain embodiments.

Some embodiments will now be described in further detail, by way of example only, with reference to the following examples and accompanying drawings, in which:

Figure 1 shows a schematic diagram of a system where some embodiments are applicable;

Figure 2 shows a schematic diagram of a control apparatus according to some embodiments; and

Figures 3 to 5 shows flowcharts according to some embodiments

Figures 6 shows a communication system supporting traffic offload where some embodiments are applicable; and Figures 7a to 7d show different endpoint embodiments.

Certain exemplifying embodiments are explained below with reference to a wireless or mobile communication system serving mobile communication devices. Before explaining in detail the exemplifying embodiments, certain general principles of a wireless communication system are briefly explained with reference to Figures 1 and 2 to assist in understanding the technology underlying the described examples.

Non-limiting examples of standards underlying communication systems include those defined by the 3^rd Generation Partnership Project (3GPP). Non-limiting examples of access nodes are a base station of a cellular system, for example what are known as NodeB (NB) and enhanced NodeB (eNB) in the vocabulary of the 3GPP specifications. The latter refers to the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) standardized by the 3GPP. These employ mobile architectures known as the Universal Terrestrial Radio Access Network (UTRAN) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN), respectively. In LTE an enhanced Node B (eNB) may provide coverage for a cell or similar radio service area and in WCDMA base systems a Node B controlled by an RNC can provide an access system. Other examples of radio access system include those provided by base stations of systems that are based on technologies such as Global System for Mobile (GSM), wireless local area network (WLAN) and/or WiMax (Worldwide Interoperability for Microwave Access).

In the wireless communication system of Figure 1 a mobile communication device or user equipment (UE) 10 can wirelessly access the communication system via at least one base station or similar wireless transmitting and/or receiving node or point of a radio network. Base stations / access systems are typically controlled by at least one appropriate controller apparatus so as to enable operation thereof. The control apparatus of a base station can be interconnected with other control entities. In Figure 1 two radio network subsystems 12 and 14 are shown, these denoting two radio access systems. A radio network subsystem may be provided for example by eNodeB, NodeB, radio network controller (RNC) or base station controller (BSC), or a NodeB with RNC functionality. Such an eNB is referred herein as -NodeB" for simplicity.

In Figure 1 access systems 12 and 14 are connected to a core network via a mobile backhaul 14 and a gateway 18. A further gateway function may be provided to connect from the core network to another network.

Figure 2 shows an example of a control apparatus, for example to be coupled to and/or for controlling one or more stations of an access system. In some embodiments base stations comprise a separate control apparatus. In other embodiments the control apparatus can be another network element. The control apparatus 30 can be arranged to provide control on communications in a service area of the system. The control apparatus can be configured to provide control functions in association with generation and communication of messages in accordance with certain embodiments described below. For this purpose the control apparatus 30 comprises at least one memory 31 , at least one data processing unit 32, 33 and an input/output interface 34. Via the interface the control apparatus can be coupled to a receiver and a transmitter of a base station and/or to the backhaul / the core network. The control apparatus can be configured to execute an appropriate software code to provide the control functions.

The inventor has found that byte caching can also be applied in mobile access networks to save transmission resources over the mobile backhaul. If byte caching is deployed in a mobile system, the caching end points can be located at the packet core network and the radio network. Caching in RAN nodes is useful in decreasing backhaul traffic and improve user experience in areas where backhaul is limited.

The end point at the radio network is preferably located as close as possible to the radio edge or interface. A reason for this is that the mobile backhaul typically produces the most costs in the transport network. Possible interfaces to place byte caching are lu/Gn in UTRAN and S1 -UP in e-UTRAN.

Figure 3 shows a flowchart in accordance with an embodiment for a method for caching where a mobility event associated with a mobile device with a caching function is determined at 40. The caching function is then informed at 42 of the mobility event. This operation may take place at an appropriate element of the radio access system, examples of which will be explained below. The mobility event can relate to handover of the mobile device to another access system.

Figure 4 shows an embodiment for caching in a caching instance of a caching function operated between caching endpoints. In the method a caching function for a mobile device is operated at 44 for data communication to and/or from the mobile device. Information regarding a mobility event associated with the mobile device is received at 46 where after the caching function is disabled at 48 in response to the received information.

Figure 5 shows an embodiment for caching in a new caching instance of a caching function operated between caching endpoints and where one of the endpoints is no longer involved in the data communication to/from a mobile device. In accordance with the method the new instance of an operational caching function associated with a mobile device is initiated at 50 in response to an indication provided in response to a mobility event associated with the mobile device. This indication can be a signal informing a caching entity associated with a new serving radio access system that a caching entity associated with the old access system has been disabled and that it is expected to assume the caching responsibility for the mobile device. The caching function for the mobile device is then operated at 52 from the new instance.

In the following examples of how caching technologies can be applied to mobile networks are described in more detail. More particularly, the following embodiments relate to relocation of a mobile device and an end point of a byte caching function in a seamless fashion. By means of this packet loss that may appear during relocation can be avoided.

In certain embodiments a byte caching function comprises an encoding algorithm. In accordance with certain embodiments caching technology is provided in radio access network nodes that experience mobility events of mobile users. Byte caching solution can be provided on a logical interface where end user packets are not encrypted. For example, byte caching may be applied on lu/Gn interface in WCDMA or S1-UP interface on LTE.

By informing caching function about forthcoming mobility events, loss of end-to- end user data may be avoided. To avoid loss of end user data in case of relocation of one endpoint of byte caching for a given end user stream. This can be provided by means of co-operation of the radio network subsystem (RNS) and its byte caching endpoint by providing information about mobility events. A RNS entity is typically aware of relocation events beforehand, and can therefore inform the relevant byte caching function(s) before the data path is switched to the new RNS.

Mobile data traffic is usually charged dependent on usage, e.g. data volume, time etc charging policies. Charging trigger function (CTF) is typically integrated into a mobile gateway, such as GPRS gateway support node (GGSN) for UTRAN or packet gateway (P-GW) for e-UTRAN. As a result optimization technology that alters data volume transmitted to the end user (mobile terminal) and is placed after the CTF can interfere with charging. Because of this byte caching may be in certain embodiments more feasible technology than object caching (e.g. HTTP proxy or transparent caching). A reason for this is that byte caching resembles compression technology in a sense that data entering the optimized link and leaving it in the other end are identical. In object caching, content is produced locally. If object caching were placed after CTF, none of the cache-served traffic would be available to the CTF. However, in the case of byte caching, original data travels through CTF and is just temporarily replaced over the optimized sequence of link.

A feature of mobile access networks, such as GSM, UTRAN and e-UTRAN is the need for enabling handovers. Radio handover from one radio carrier to another may cause relocation of access node through which data stream of the handed over user is transported. For example, it may cause redirecting users traffic tunnel (e.g. GPRS Transport Protocol (GTP) tunnel) from one radio network subsystem to another. This can be problematic in view of application of byte caching algorithms to mobile systems. It means the other endpoint of the caching function may change any time for a given data flow. Byte caching algorithms typically rely on a state that is a shared, coherent state between the two endpoints of the function. This means that an encoding endpoint assumes that the decoding end knows and has the data pointed by the token transmitted over a link.

Figure 1 shows an endpoint (A) of byte caching as being implemented in mobile packet core network. The CTF is provided between the endpoint (A) and Gi/SGi interface 20 to ensure correct charging The other endpoint (B1 , B2) is provided in the respective radio network subsystem (RNS). The operation can be as follows:

1 ) A mobile terminal UE 10 is served by a RNS 12 associated with a byte caching function endpoint B1 .

2) Byte caching function operated between endpoints B1 and A recognizes that endpoint B1 has a chunk of data being transmitted to the UE already cached. The byte caching function replaces original data stream or packets between endpoints A and B1 with tokens.

3) Relocation procedure from the first RNS (source) 12 to a second RNS (target) 14 is initiated. As a part of preparation for relocation of the UE 10 from the source RNS 12 to the target RNS 14, the source RNS informs the byte caching function instance in endpoint B1 about the forthcoming mobility event.

4) Endpoints B1 and A prepare for the relocation by disabling use of the tokens. The original, unchanged data stream can be sent towards the UE without caching.

5) A relocation event takes place due to radio handover to the target RNS. At this stage byte caching endpoint B2 associated with the target RNS becomes active. Data stream for the UE 10 flows now via caching end point B2 instead of B1.

6) Caching endpoint B2 receives unencoded data stream of the UE. If B2 founds that it has a relevant downlink data pattern cached it may negotiate with A to re-enable replacement of data stream or packets with tokens. B2 may have been provided with the data pattern by various manners. For example, the dayta may already be cached due to someone else accessing the same content earlier through B2.

In this way, loss of end user data may be avoided, or at least the amount of lost data reduced. The procedure is not believed to have any remarkable, or even noticeable, impact on efficiency of the caching. Co-operation between a RNS and a local endpoint of a byte caching function is a local operation, and therefore no major changes, if any changes at all, may be needed to existing protocol / interface specifications of the mobile networks.

In accordance with an embodiment the step of informing about forthcoming handover may be provided by integrating another endpoint of the caching function into a network element providing the radio network subsystem (RNS), such as NodeB, eNodeB, RNC or l-NodeB. According to an alternative, the other endpoint of the caching function is provided in a separate system hooked into lu or S1 interface, and thus connected with the RNS. In this case indication can be transferred to the caching algorithm e.g. over an appropriate network protocol between the system and the RNS. The protocol can be an independent protocol that is not standardized e.g. by 3GPP. Alternatively, a relocation indication can be implemented implicitly by monitoring procedures related to relocations or handovers on existing signalling interfaces, for example based on Radio Access Network Application Part (RANAP) protocol on lu-PS signaling interface (3GPP Technical Specification 25.413 version 10.5.0, published 2012-03), or S1-AP protocol on S1-AP interface (3GPP Techical Specification 36.413 version 10.5, published 2012-03). These documents are incorporated herein by reference.

A limitation of byte caching in certain occasions may be that it may not be effective on encrypted user data. This may make its applicability on certain interfaces difficult, for example on the lub in UTRAN or Gb in GSM. Nevertheless, caching may also be applied even on encrypted interfaces if decryption of data is provided or the caching algorithm can operate on encrypted data.

The method may be applicable to other caching methods as well, which have two functional endpoints, require a coherent state and are transparent for the end-to- end TCP flow, for example between an UE and Internet. Other example embodiments may comprise include compression algorithms and decompression algorithm with two endpoints. Embodiments may be used where there are local break out and off load solutions. This may be in the context of a 3GPP radio environment or any other suitable environment. In some embodiments, applications may be deployed to offload points using for example cloud style application deployments. Local breakout functions may provide a mechanism to serve traffic by local applications. In other words, Internet content or the like is brought to a local breakout point. There are many use cases of localization. By way of example, this may be one or more of a local content delivery network (CDN), local transparent caching, local content optimization for a mobile terminal and/or network, local hosting of other kind of services (used by mobile terminals), and local serving of machine-to-machine (M2M) terminals, for example aggregation functions or the like.

Local breakout may be applied alternatively or additionally to other types of radio networks, such as Wi-Fi, WiMax and Femto network. In such embodiments the offload may be between core network and Internet transit/peering.

Some embodiments may integrate a server module or function into the RAN (Radio Access Network). This application server function may be considered to be a RACS (Radio Applications Cloud Server). It should be appreciated that this application server function may be a cloud server or any other suitable server. The RAN may be provided by one or more entities. In some embodiments, the RAN may comprise a BTS (base transceiver station) to which an RNC (radio network controller) has been integrated or RNC in a 3G network, or an eNB (enhanced Node B) in LTE (Long term evolution). It should be appreciated that other embodiments may alternatively or additionally be used in conjunction with any other suitable standard or system.

The application server function may enable the deployment and hosting of local applications at the RAN side in a virtualization computing environment and applying cloud technologies. The "leaky bearer" offload concept may be applied to gain access to the mobile bearer traffic flows. The traffic flows may be IP traffic flows. By way of example the IP traffic flows may comprise one or more of PDP (packet data protocol) context and EPS (evolved packet system) bearer.

Local breakout scenarios are specified in 3GPP release 10 under the name SIPTO (selected IP traffic offload). One of the concepts for 3G networks is the so-called "leaky bearer" traffic flow break-out, also called TOF (Traffic offload). It allows extracting or inserting IP flows of an existing mobile bearer based on activated IP flow traffic filters. This is a flexible break-out concept without involvement of or impact on the UE (user equipment). The concept provides local access to mobile bearer traffic flows and in this way is used for the deployment and execution of applications at the RAN like CDN (content delivery network) solutions, content delivery optimization, caching solutions or others. These local applications may benefit from the proximity to the radio (e.g. location awareness, lower latency) and of having access to radio information, e.g. radio cell load, location, UE's specific radio condition.

It should be appreciated that some embodiments may alternatively or additionally use different local breakout techniques other than those discussed above.

Reference is now made to Figure 6 which shows one example of a schematic architecture. In this example, an application server function 138 may be integrated at the RAN 139 level with an off load capability. The applications which may be supported by the architecture may have distributed and centralized components.

The network architecture broadly comprises a radio access side 132 and a mobile packet core 134. The radio access side comprises user equipment 10. The user equipment are configured to communicate with a respective radio access network. In Figure 6, first, second and third radio access networks 139 are shown. Each RAN may comprise one or more access nodes. The access nodes may comprise any suitable access node. Depending on the standard involved, the access node may be a base station such as a node B with at least some RNC functionality or an enhanced node B. The latter refers to the Long Term Evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) standardised by 3GPP (Third Generation Partnership Project). A controller for the base stations may be provided. In some standards, the controller may be a radio network controller. The radio network controller is able to control the plurality of base stations. In other embodiments, a distributed control function is provided and each base station incorporates part of that control function.

Each of the RAN shown in figure 6 is provided with a server such as an application server function. The application server function 38 may be provided by a separate entity or may be integrated with one or more other entities.

The application server function may be integrated with a base station 39 having at least some RNC functionality and/or RNC or any other type of controller. It should be appreciated that other embodiments are additionally or alternatively envisaged such as where server functionality is integrated into a node of the RAN, for example the RNC or the base station having for example RNC functionality. In some embodiments, a physical realisation would be a RNC/base station plus server in a same integrated hardware. In some embodiments the physical realisation or hardware may be different. A physical realization may be different (for example an integrated one), even though the software functionality may be the same or similar, in some embodiments. The mobile packet core 134 comprises mobile gateway node 146 and 148. The mobile gateway may be a GGSN (gateway GPRS (General Packet Radio Service) support node) and the mobile gateway 148 may be a (PGW) packet gateway. These gateways are by way of example. One or more other types of gateway may additionally or alternatively be provided in different embodiments. Only one type of gateway may be provided in some embodiments. More than one type of gateway may be provided in other embodiments.

The mobile packet core 134 also comprises a mobile network control part 54. This part comprises SGSNs (serving GPRS Support Node) and MMEs (mobile management entities) entities 156 and 158.

In some embodiments, the mobile packet core 134 may comprise a function 160. This function may provide one or more of a lawful intercept function which allows authorised authorities to monitor communications, policy control function and charging control function. One or more of these functions may be provided separately and/or in different combinations.

The radio access part 132 is able to communicate with the mobile packet core via connectivity and transport function 162.

The application server function 138 may host applications, which can be accessed by subscribers via leaky bearer traffic offload. For example, a subscriber can access applications hosted by the server 138 via the offload of respective IP flows of the subscriber's mobile bearer to the corresponding application.

Pass through applications are ones which pass end to end packet flows through modified or un-modified, potentially altering the scheduling of the packets. These are sometimes called virtual appliances. A pass through application may be a virtual machine image with complete application functionality, such as a server containing a transparent cache. Terminating applications are applications which terminate end to end packet flows, providing a service and are therefore visible as IP flow endpoints to terminals using the network. The terminating application may be a virtual machine image with complete application functionality such as a server for a content delivery network. Analytics applications are applications which need to see end to end packet flows but do not modify the packet content or flow scheduling.

An embodiment providing byte caching function may be instantiated as a pass through application.

Some embodiments may provide an application server or application server platform. Some embodiments may use traffic off load. By way of example only, some embodiments may use SIPTO (selected IP traffic off load). SIPTO may for example allow Internet traffic to flow from a femto cell directly to the Internet, bypassing the operator's core network. However, it should be appreciated that SIPTO is one example of traffic off load and other embodiments may alternatively or additionally be used with any other traffic off load.

In embodiments, applications are run within a logical entity called the application server. By way of example only, the application server can be instantiated in one or more of the following scenarios as illustrated in Figure 7.

The RAN 200 comprises one or more of a RNC, l-HSPA, eNode B, node B, base station and/or any other controller and/or any other type of radio access node. It should be appreciated that the elements which comprise the RAN may be defined by the relevant standard. The packet core elements 204 may comprise a SGSN and/or a GGSN. In Figure 7a the application server 202 is provided between the RAN 200 and the packet core 204.

Reference is made to Figure 7b in which, alternatively or additionally, the application server is connected to the RAN 200 but not directly to the packet core network elements 204. The application server 202 would be connected to the packet core via the RAN.

Figure 7c shows the application server 202 integrated within the RAN. The application server 202 may be integrated in one or more of the components of the RAN. The RAN 200 is coupled to the packet core 204.

In Figure 7d, the application server 202 may be integrated within the packet core 204. The application server may be incorporated in one or more of the packet core elements. The packet core 204 is connected to the RAN 200.

A network or system may comprise one or more of the options shown in Figure

7.

In Figure 7a, the end point A of the byte caching may be provided in the packet core network element, on the radio access network side of the packet core element (for example on the GN/S5 interface or on the other side of the packet core network element, for example on the Gi/SGi interface. Thus, the endpoint A may be deployed in the packet core. The packet core element may be a GGSN or PDGW.

In some embodiments, it may be preferred to provide the endpoint A in the core network element or on the GN/S5 interface side of the core network element.

The second end point B may be provided in the application server 202 or on the lu interface with the packet core side. In relation to the arrangement of Figure 7b, the possible locations for the endpoint A are the same as discussed in relation to Figure 7a. The byte caching function endpoint B may be provided in at least one of the RAN application server 202, the RNC/I-HSPA node B/eNodeB 200 and on the lu interface towards the packet core.

In Figure 7c, the possible locations for the endpoint A are the same as discussed in relation to Figure 7a. The B endpoints may be provided in at least one of the application server and on the lu interface.

In relation to figure 7d, the possible locations for the endpoint A are the same as discussed in relation to figure 7a. The B endpoint may be put be provided in at least one of the RNC/I-HSPA NodeB/eNodeB 200 and on the GN/S5 interface.

The byte caching endpoints A and B may operate in any of the ways described previously both when there is mobility and during normal operation.

The required data processing apparatus and functions of a control apparatus in relevant parts of the communication system, e.g. core network and radio access system, for causing operation in accordance with the above described principles may be provided by means of one or more data processor. The described functions may be provided by separate processors or by an integrated processor. The data processors may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), gate level circuits and processors based on multi core processor architecture, as non limiting examples. The data processing may be distributed across several data processing modules. A data processor may be provided by means of, for example, at least one chip. Appropriate memory capacity can also be provided in the relevant devices. The memory or memories may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory.

An appropriately adapted computer program code product or products may be used for implementing the embodiments, when loaded or otherwise provided on an appropriate data processing apparatus. The program code product for providing the operation may be stored on, provided and embodied by means of an appropriate carrier medium. An appropriate computer program can be embodied on a computer readable record medium. A possibility is to download the program code product via a data network. In general, the various embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Embodiments of the inventions may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large an automated process. Complex and powerful tools are available for converting a logic level design into a semiconductor circuit design ready to be formed on a semiconductor substrate.

It is noted that whilst embodiments have been described in relation to certain technologies such as LTE and WCDMA radio access and GPRS based core networks, similar principles can be applied to any other communication system where direct communication of access system related information between different parts of the system may be desired. Therefore, although certain embodiments were described above by way of example with reference to certain exemplifying architectures for wireless networks, technologies and standards, embodiments may be applied to any other suitable forms of communication systems than those illustrated and described herein.

The foregoing description has provided by way of exemplary and non-limiting examples a full and informative description of the exemplary embodiment of this invention. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. For example, a combination of one or more of any of the other embodiments previously discussed can be provided. All such and similar modifications of the teachings of this invention will still fall within the spirit and scope of this invention.

Claims

1. A method, comprising:

determining a mobility event associated with a mobile device with a function with a coherent state; and

informing the coherent function of the mobility event.

2. A method, comprising:

operating a function with a coherent state for a mobile device;

receiving information regarding a mobility event associated with the mobile device; and

disabling the coherent function in response to the information.

3. A method, comprising:

initiating a new instance of an operational function with a coherent state associated with a mobile device in response to an indication in response to a mobility event associated with the mobile device; and

operating the coherent function for the mobile device from the new instance.

4. A method as claimed in any preceding claim wherein said function with a coherent state comprises at least one of a caching function and a compression and/or decompression algorithm.

5. A method as claimed in any preceding claim, wherein the coherent function provides byte caching.

6. A method as claimed in any preceding claim, wherein said coherent function is provided between a first endpoint in a packet core network and a second endpoint in a radio network.

7. A method as claimed in claim 6, wherein said second endpoint is provided in radio access network.

8. A method as claimed in claim 6 or 7, wherein said second endpoint is provided in at least one of a breakout application server, a radio network controller, and a base station.

9. A method as claimed in claim 6, 7 or 8, comprising communicating information of the mobility event to a communicated to the second endpoint.

10. A method as claimed in any preceding claim, comprising informing by the second endpoint to the first endpoint of the mobility event.

1 1 . A method as claimed in any preceding claim, comprising communicating said information on a lu, Gn, or S1 -U interface.

12. A method as claimed in any preceding claim, comprising transferring at least one caching function endpoint another location in response to the mobility event.

13. A method as claimed in any preceding wherein said mobility event comprises at least one of a handover of the mobile device and relocation of the mobile device from a first radio system to a second radio access network.

14. A computer program comprising program code which when run causes the method of any one of the preceding claims to be performed.

15. An apparatus comprising

at least one processor and

at least one memory including computer program code

the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform:

determine a mobility event associated with a mobile device with a function with a coherent state, and

inform the coherent function of the mobility event.

16. An apparatus comprising

at least one processor and

at least one memory including computer program code the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform:

provide a function with a coherent state for a mobile device, receive information regarding a mobility event associated with the mobile device, and

disable the coherent function in response to the information.

17. An apparatus comprising

at least one processor and

at least one memory including computer program code

cause initiation of a new instance of an operational function with a coherent state associated with a mobile device in response to an indication generated in response to a mobility event associated with the mobile device, and

provide the coherent function for the mobile device from the new instance.

18. An apparatus claimed in claim 15, 16 or 17 wherein said function with a coherent state comprises at least one of a caching function and a compression and/or decompression algorithm.

19. An apparatus as claimed in any one of claims 15 to 18, wherein the coherent function provides byte caching.

20. An apparatus as claimed in any one of claims 15 to 19, wherein said coherent function is provided between a first endpoint in a packet core network and a second endpoint in a radio network.

21 . An apparatus as claimed in claim 20 further configured to perform: communicating information of the mobility event to a communicated to the second endpoint.

22. An apparatus as claimed in any one of claims 15 to 21 , further configured to perform: informing by the second endpoint to the first endpoint of the mobility event.

23. An apparatus as claimed in any one of claims 15 to 22 further configured to perform communicating said information on a lu, Gn, or S1-U interface.

24. An apparatus as claimed in any one of claims 15 to 23 further configured to perform transferring at least one caching function endpoint another location in response to the mobility event.

25. An apparatus as claimed in any one of claims 15 to 24 wherein said mobility event comprises at least one of a handover of the mobile device and relocation of the mobile device from a first radio system to a second radio access network.