WO2008116488A1

WO2008116488A1 - Method for providing media independent handover (mih) services to a communication node

Info

Publication number: WO2008116488A1
Application number: PCT/EP2007/002751
Authority: WO
Inventors: Telemaco Melia; Albert Vidal; Albert Banchs
Original assignee: Nec Europe Ltd.
Priority date: 2007-03-28
Filing date: 2007-03-28
Publication date: 2008-10-02

Abstract

A method for providing media independent handover (MIH) services to a communication node, preferably according to the IEEE 802.21 standard, wherein the communication node (1) is attached to a network via a Point of Attachment (PoA) which has access to an information database (IS) via appropriate network entities, and wherein information, upon a respective request from the communication node (1), is forwarded from the information database (IS) to the communication node (1), is characterized in that a caching functionality is enabled at at least one network entity - caching entity - on the path between the communication node (1) and the information database (IS), wherein the information forwarded from the information database (IS) to the communication node (1) is stored at the caching entity.

Description

METHOD FOR PROVIDING MEDIA INDEPENDENT HANDOVER (MIH) SERVICES TO A COMMUNICATION NODE

The present invention relates to a method for providing media independent handover (MIH) services to a communication node, preferably according to the IEEE 802.21 standard, wherein the communication node is attached to a network via a Point of Attachment which has access to an information database via appropriate network entities, and wherein information, upon a respective request from the communication node, is forwarded from the information database to the communication node.

In recent years several types of wireless communication systems have been developed. For example, wireless local area networks (WLAN) are widely spread nowadays, cellular networks, such as Universal Mobile Telecommunication Systems (UMTS), have gained paramount importance, and, most recently, WiMAX (defined as Worldwide Interoperability for Microwave Access) has been developed as a standard-based technology enabling the delivery of last mile wireless broad band access. Each of these systems provides different types of services and specific applications.

For seamless handover between different types of networks, the IEEE 802.21 MIH (Media Independent Handover) specification has been developed. The scope of the IEEE 802.21 standard is to develop a specification that provides link layer intelligence and other related network information to upper layers to optimise handovers between heterogeneous media. In this context, "media" refers to the method or mode of accessing a telecommunication system (e.g. cable, radio, satellite, etc.), as opposed to sensory aspects of communication (e.g. audio, video, etc.).

The standard aims at providing means to improve handovers across heterogeneous networks by sharing information, events and commands between MIH peers which, generically, will be referred to in the following as communication nodes. In general, a communication node is any sort of a mobile terminal. The Information Service, for sharing information between communication nodes, is one of the key concepts of the MIH architecture. This service assumes a centralized information database which resides in the operator's core network and which, in the context of the 802.21 standard, is referred to as Information Server. The data stored in this database provide information about the neighbouring networks of a communication node. Consequently, a communication node may request information from the database such as Network Type, Operator Identifier, Service Provider Identifier, Access Network Identifier, Roaming Partners, Cost, Network Standards, Security in Network, QoS in the Network, etc. Every time a communication node needs to update this kind of information it may send a respective query to the information database.

When MIH peers or communication nodes cannot communicate directly with each other, they have to communicate through an intermediary MIH entity which will forward the messages acting as a proxy. This procedure is defined as multi-hop or proxy-operation. For cases in which an information requesting communication node is not directly connected to its Information Server it may first send a request message to its Point of Attachment. A Point of Attachment may be a node to which the communication node is attached, and which has access to the Information Server, either directly or indirectly via appropriate network entities that forward the request to the correspondent Information Server, acting as an intermediary or proxy.

The procedure of requesting and providing information between a communication node and a centralized information database as described above is rather inefficient for quite common scenarios. In practice, many network entities on the path between the requesting communication node and the information database are involved in this procedure. Thereby, an extensive signalling overhead is produced across the network which proves to be especially disadvantageous in wireless communication networks with reduced bandwidth. Moreover, the network behaviour is strongly affected by the network size. In other words, an increase in the number of users implies more signalling overhead resulting in scalability problems.

It is therefore an object of the present invention to improve and further develop a method of the initially described type for providing media independent handover services to a communication node in such a way that by employing mechanisms that are readily to implement a performance improvement in terms of scalability and efficiency is achieved, while the communication overhead is reduced compared to the schemes according to the state of the art.

In accordance with the invention, the aforementioned object is accomplished by a method comprising the features of claim 1. According to this claim such a method is characterized in that a caching functionality is enabled at at least one network entity - caching entity - on the path between the communication node and the information database, wherein the information forwarded from the information database to the communication node is stored at the caching entity.

According to the invention it has first been recognised that the data overhead can be significantly reduced by enabling a caching functionality at at least one network entity between the communication node and the information database. The network entity (or entities) at which the caching functionality is enabled is referred to as caching entity. Any network entity that is located on the path between the communication node and the information database may be chosen as caching entity. According to the invention the caching functionality is implemented in such a way that information forwarded from the information database to the communication node is stored at the caching entity.

The invention on the one hand takes advantage of the fact that, in general, the information stored in the information database is defined as static kind of information that does not change very often. A communication node requesting the same information, which a previous communication node had requested a certain time period before, can therefore grip the requested information from the caching entity without having to access the information database. On the other hand, the invention further takes advantage of the fact, that due to reduced-size cells (like, for example, in WLAN Hotspots, 3G pico/femto cells, etc.) the distance between two communication nodes is not to large so that the same information will be valid for both communication nodes. Thus, the method according to the invention avoids sending of the same information many times to network locations that are nearby. As the number of intermediary hops which are involved in the information request process is drastically reduced, the scalability is enhanced, thereby allowing an application in larger network architectures. In an especially advantageous embodiment the caching functionality is enabled at the point of attachment of the communication node. By choosing the point of attachment as caching entity the highest reduction of signalling overhead can be realized since the information request flow for cached data will arrive only to the point of attachment. All other network entities located behind the point of attachment on the path between the communication node and the information database are, however, not affected by the data flow. In typical network configurations, like e.g. a WiMAX backhaul or a WiFi mesh, this reduced data flow results in a significant improvement in efficiency. Furthermore, the closer the caching entity is located to the communication node, the shorter will be the response time to the communication node.

The communication node may be a mobile node or any network entity. Correspondingly, the point of attachment may be an access point, a Node B or another network entity adapted to the properties of the communication node.

Advantageously, the caching functionalities are implemented in such a way that information that is forwarded from the information database to a requesting communication node is stored in a cache database at the caching entity. As regards an efficient handling of the cache database and a differentiated access, the information before being stored in the cache database at the caching entity may be divided into individual information elements that are referred to as IE. Each information element IE may be assigned an individual code which may be consistent with the code as defined in the IEEE 802.21 specification.

In a preferred embodiment an expiration period is defined for each information element giving the time period the respective information element will be stored at the caching entity. Alternatively, the expiration period may be defined as the time period during which a value stored in the cache database is considered valid. In any case, the expiration period defines the time period in which - if another request for the respective information element is made - the stored value will be provided back to the requesting communication node. The expiration period may be defined as a parameter which is different for every different information element. It can be computed by the caching entity or may be provided by any other entity of the network.

Alternatively or additionally, an area of validity may be defined for each information element giving the (spatial or logical) region for which the respective information element is considered valid. If the request message of a communication node includes location information of the node (e.g. geospacial), the caching entity will deliver the value stored for the requested information element to the requesting communication node if the stored value is valid for the location of the communication node. The expiration period as well as the area of validity may be implemented as parameters which are configurable for each information element separately. As with the expiration period the area of validity may be computed by the caching entity itself or may be provided by any other network entity. As a most simple example, the area of validity may have a preconfigured value for each of the information elements.

In a concrete embodiment, the caching entity, upon receipt of an information request from a communication node, checks if the cache database contains a valid value (as regards time and/or space) of each specific information element requested by the communication node. If the values of all requested information elements prove to be valid, the caching entity forwards all values to the requesting node. If one or more values of the requested information elements prove to be invalid, there may be provided two different ways of how to proceed. According to a first embodiment the caching entity forwards the valid values directly to the requesting node. Furthermore, the caching entity refreshes the values of those requested information elements for which the cache database does not contain a valid value by requesting the respective values from the information server and forwards the refreshed values by means of a second message to the requesting node. In contrast, according to a second embodiment the caching entity may first refresh the invalid values and may subsequently forward the values of all requested information elements together in one single message to the communication node. The latter method has the advantage of a reduced signalling overhead, whereas the communication node receives a quicker response with the first embodiment. With respect to an efficient handling of the cache database, the storage of information elements may be arranged according to configurable criteria. For example, the information elements could be stored in the cache database with an order corresponding to their amount of being requested. By ordering the information elements in the database according to their number of hits, the information elements with a high probability of being requested will be positioned first in the database and, therefore, a rather short response time can be achieved for frequently requested information.

With respect to a further reduction of the response time, the caching entity may be operated in a proactive way. This means that the caching entity updates values of information elements that became invalid due to expiration in a self-dependent manner. In other words, the refreshment is coupled to the expiration period of the information element and does not depend on a request message from a communication node for that information element.

It is noted that the method as described herein may be applied to many different kinds of services. For example, the method may be applied for an information service, a command service, or an event service. Although the current definition of the multi-hop or proxy functionality in the 802.21 specification does not include command and event services, it is likely that future versions of this specification will include also these types of service. In this context it becomes clear to someone skilled in the art, that the method as described above may be applied for any other service. By way of example, the information service provided by an Information Server may include retrieval of information related to the neighbouring networks of the communication node and the command service, for instance, may include an enforced handover of a communication node.

There are several ways how to design and further develop the teaching of the present invention in an advantageous way. To this end it is to be referred to the patent claims subordinate to patent claim 1 and to the following explanation of preferred embodiments of the invention by way of example, illustrated by the figure on the other hand. In connection with the explanation of the preferred embodiments of the invention by the aid of the figure, generally preferred embodiments and further developments of the teaching will we explained.

In the drawings:

Fig. 1 is a schematic view of a typical network architecture illustrating the MIH communication model in general,

Fig. 2 is a diagram showing the IS multi-hop operation according to the state of the art,

Fig. 3 is a schematic view of a network architecture illustrating the network entities which are involved in an information request process,

Fig. 4 is a diagram showing the basic communication principle of an information request process according to an embodiment of the invention,

Fig. 5 is a diagrammatic illustration of the message exchange during an information request process according to the state of the art,

Fig. 6 is a diagrammatic illustration of the message exchange during an information request process according to an embodiment of the invention, and

Fig. 7 is a state diagram of the logic behaviour of a caching entity according to an embodiment of the invention.

Figure 1 illustrates a network model including MIH services in which the method according to the invention is applicable. More particularly, Figure 1 gives an illustration of the MIH communication reference points in a network architecture. The model includes an MIH capable communication node 1 which supports multiple wired and/or wireless access technology options. The model shown in Figure 1 includes four exemplary access networks 1 -4. The access networks 1 , 2 and 4 are connected to a core network (Operator 1-3 Core, respectively), whereas access network 3 is a cellular network which is coupled to a core network that is labelled as Visited/Home Core Network. In this context the terms visited and home indicate the provisioning service provider or enterprise. Any of the illustrated networks can be either a Visited or Home Network depending on the relation of the operator to the provisioner of the communication node 1. The Operator 1-3 Core each might represent a service provider or corporate intranet provider.

Network providers offer MIH services in their access networks (Access Networks 1-4) to facilitate handover into their networks. Each access technology either advertises its MIH capability or responds to MIH service discovery. Each service provider for the access network allows access to one or more MIH Points of Service (PoS). These PoS may provide some or all of the MIH services as determined during MIH capabilities discovery. The location or node of an MIH PoS is not fixed by the standard. The PoS location may vary based on operator deployment scenario and the technology-specific MIH architecture.

An MIH PoS may reside next to or be co-located with the point of attachment (PoA) in the access network (in this regard Access Networks 1 , 2, and 4 are typical). Alternatively the PoS may reside deeper inside the access or core network (in this regard Access Network 3 is typical). As shown in Figure 1 , the MIH entity in the communication node 1 communicates with MIH network entities either by R1 , R2 or R3 over any access network. According to the 802.21 the communication reference points R1-R5 shown in Figure 1 are defined as follows:

R1 refers to MIHF (Media Independent Handover Function is a functional implementation of MIH services as defined in the 802.21 specification) procedures between the MIHF on the communication node 1 and the MIH PoS on the Network Entity of its serving PoA. R2 refers to MIHF procedures between the MIHF on the communication node 1 and the MIH PoS on the Network Entity of a candidate PoA. Candidate PoAs are PoAs that the communication node 1 is aware of but not currently attached to; it becomes the target PoA if a handover eventually occurs. R1 and R2 may encompass communication interfaces over both L2 and L3 and above. R3 refers to MIHF procedures between the MIHF on the communication node 1 and the MIH PoS on a non-PoA Network Entity. R3 may encompass communication interfaces over L3 and above and possibly L2 transport protocol like Ethernet bridging, MPLS, etc. R4 refers to MIHF procedures between an MIH PoS in a Network Entity and an MIH non-PoS instance in another Network Entity. R5 refers to MIHF procedures between two MIH PoS instances in distinct Network Entities. R4 and R5 may encompass communication interfaces over L3 and above. MIHF content passed over R1-R5 may be related to MIIS (Media Independent Information Service), MIES (Media Independent Event Service), or MICS (Media Independent Command Service).

The interaction of visited and home network could be either for control and management purposes or for data transport purposes. It is also possible that due to roaming or SLA agreements, the home network may allow the communication node 1 to access the public Internet directly through a visited network. As illustrated, two MIH network entities may communicate with each other via R4 or R5 reference connections. The MIH capable PoA may also communicate with other MIH network entities via R3 and R4 reference points. The MIH capable communication node 1 could have a MIH communication with other PoA in the candidate access networks via R2 reference points to obtain information services about the candidate network.

With regard to the MIH Information Service (MIIS) the providers offer access to their information server located in a MIH PoS node (upper far left). The operator provides the MIIS to communication nodes so they can obtain pertinent information including but not limited to new roaming lists, costs, provider identification information, provider services, priorities and any other information that would enable to select and utilize services. It is possible for the communication node 1 to be pre-provisioned with MIIS data by its provider. Also possible is for the communication node 1 to obtain MIH information services from any access network of its provider. MIIS could also be available from another overlapping or nearby network, using that network's MIIS point of service. A provisioner's network (depicted here as coupled with Access Network 3) may utilize R3 and R4 interfaces to access other MIH entities like the provisioner's or visited network's MIH information server. With regard to the MIH Command Service (MICS) the Information Database (far left, mid-way down) depicts a command service PoS. The communication node's 1 MIHF typically communicates with this server using a layer three transport.

Based on the general architecture according to the 802.21 standard as described with respect to Figure 1 , Figure 2 is an illustration of the IS multi-hop operation according to the standard. For those cases in which the communication node 1 is not directly connected to its Information Server, it contacts the server via its PoS (Point of Service) which forwards the request to the corresponding Information Server, acting as an intermediary or proxy. This functionality is described in the current v.2.0 of the 802.21 draft as follows:

"In Information Service, an MIH PoS may acts as an intermediary entity which forwards MIH messages carrying IS payloads (i) between a mobile node and a non- PoS MIH, (ii) between a mobile node and another MIH PoS or (iii) between another MIH PoS and a non-PoS MIH. The role of such an intermediary is to splice an IS transaction path into multiple IS transaction segments. The two MIH nodes of an IS transaction segment act as an IS client and server. Existence of other IS transaction segments of the same IS transaction path are not visible to the MIH nodes, i.e., an MIH node will not know whether its MIH peer is further forwarding IS messages to another MIH node."

This procedure can be significantly inefficient what becomes clear when considering Figure 3 which illustrates the architecture of network entities which are typically involved in an information request process carried out according to the 802.21 specification. The simple operator architecture as shown in Figure 3 comprises several Points of Attachment (PoA) to which in total eight communication nodes 1 are attached. In the illustrated example the communication nodes 1 are mobile nodes MN1 to MN8. The PoAs at the same time are connected to a backhaul router (non- PoS) through which the PoAs can access the Information Server IS. Each information request message as well as the respective response takes the full path from the requesting communication node 1 to the Information Server IS, and vice versa, regardless of whether requesting nodes that are located close together request the same information within a rather short time period. The consequences of this data flow are an enormous signalling overhead as well as scalability problems.

Figure 4 is a diagram illustrating the basic communication scheme according to the invention. A MIH proxy entity as a network entity at which a caching function is enabled is located somewhere in between a communication node 1 and a MIH information server IS. The logical order for the message sequence is the following: First, the communication node 1 sends a standard MIH_Get_lnfo.Request which, as defined in the IEE 802.21 specification, includes two optional fields: the location (e.g. geospacial) of the communication node 1 and a template with the information element IE the communication node 1 wants to retrieve. It is to be understood, that both fields are optional.

When the request arrives at the MIH proxy entity, which is designed as a cashing entity according to the invention, the MIH proxy will check whether there is any of the information requested by the communication node 1 available and valid in the proxy's cash database. In case the information is available at the proxy's cash database a MIH_Get_lnfo.Request will be provided back to the communication node 1 immediately. For the information elements that are not available or not valid at the proxy's cash database, the proxy will forward the MIH_Get_lnfo. Request to the appropriate MIH Information Server. Once the Information Server has collected all information from its database it will send the MIH_Get_lnfo.Response to the communication node 1 via the MIH proxy entity. The MIH proxy entity divides the information into individual information elements IE and saves them in the cash database, either updating existing IEs or creating new entries in the database.

As regards the validity of information elements it is to be noted that in the case the location is not specified in the request message, the response will include a larger set of valid information. Moreover, if the template of IEs that are requested is not specified, the whole set of IEs defined and available in the MIH information server database will be delivered.

Figure 5 is a diagrammatic illustration of the messages exchanged during an information request process according to the 802.21 specification. There are in total n communication nodes 1 (mobile nodes MNI-MNn). In a vertical direction of the diagram events related to an information request of the mobile nodes MNi at the Information Server IS are given in a chronological order. First, mobile node MN1 attaches to the Point of Attachment PoA. At a certain point in time MN1 sends a MIH_Get_lnfo.Request to the PoA. At the PoA this information request message is forwarded to a backhaul router non-Pos and from there it is forwarded to the Information Server IS. At the Information Server IS the requested information is collected and is send via a MIH_Get_lnfo.Response message to the non-PoS. From there the message is forwarded to the PoA and from there finally to the requesting communication node MN1.

A short time period later, mobile node MN2 attaches to the same PoA and requests the same information as mobile node MN1 requested before. It is noted that this scenario is expected to be quite common as, in practice, communication nodes are likely to always request the same information when attaching to a new PoA. The respective request message is forwarded via the PoA and a non-PoS to the IS as described above. The same process is repeated and the same messages are exchanged every time a new mobile node attaches to that PoA requesting the same information. The repetition is indicated by depicting the message exchange for an arbitrary mobile node MNn.

In Figure 6 the same architecture is shown as in Figure 5 and the same objects are labelled with the same references. Furthermore, the attachment of communication node MN1 at the PoA and the information retrieval of Mn1 at the Information Server IS is basically the same as in Figure 5. However, according to the invention a caching functionality is enabled at one network entity - caching entity - on the path between the communication node 1 and the Information Server IS. In the embodiment shown in Figure 6 the Point of Attachment PoA is designed as caching entity with a cache database in which the information sent back from the Information Server IS upon a request from mobile node 1 is cached.

As illustrated in Figure 5, a short period in time later communication node MN2 attaches to the same PoA and requests the same information as MN1. In contrast to the scheme shown in Figure 5, the requested information can now directly be retrieved from the cache database at the PoA without involving neither the information server nor any other intermediary entities. By enabling a caching functionality at the PoA the efficiency is significantly increased due to a reduced signalling overhead in the network as the information request flow for cached data will arrive only at the PoA instead of the IS. Furthermore, the latency is reduced as the response time to the communication node 1 is reduced to the same reasons as described above. Finally, the scalability is in enhanced since the signalling overhead is kept between the communication nodes and the PoA whereas all intermediary hops in the network up to the Information Server IS are not involved. Especially in scenarios with four or five or even more hops between the mobile nodes and the Information Server (instead of the two hops like in the example described here in the context of Figure 6) the caching functionality yields an enormous scalability gain. As well, if one considers typical WLANs with maybe 25 or more users, the overhead reduction is very significant which leads to more scalable network architectures.

Figure 7 is a state diagram which determines the logic behaviour of the caching entity according to an embodiment of the invention. Upon receipt of an information request from a communication node 1 , as illustrated in the upper left part of Figure 7, the caching entity first checks whether the location of the requesting communication node 1 is specified in the information request message. If the location is specified, the caching entity checks whether the IE template container is specified. If so, the requested information is fragmented into individual information elements IE.

In a next step the caching entity searches the cache database for the individual information elements IE according to their IDs. For all requested information elements it is checked whether there is an entry for that information element in the cache database, whether the value cached for an information element possesses validity regarding the area from which the information request originates, and, finally, whether the value stored for an information element possesses validity regarding the expiration period. From the location point of view it might happen that the cache database contains more than one entry of the same information element IE which belong to different areas of validity. Such multiple entries are particularly recommended for networks with larger cell sizes like WiMAX, for example. If all three checks are answered in the positive, the caching entity prepares an IS response MIH frame and forwards the result to the information requesting communication node 1. In the case that one of the checks is answered in the negative, i.e. there is no entry for that IE in the cache database, the requesting node 1 is outside the area for which the value stored for the IE is valid, or the value stored for the IE is outside its expiration period, the caching entity prepares to forward the IS request MIH frame to the Information Server. The Information Server collects the relevant data and forwards the requested information to the caching entity. This input at the caching entity is depicted in the upper right part of Figure 7.

Upon receipt of the result form the Information Server the caching entity fragments the information into individual information elements IE and, subsequently, performs an update of its cache database for each of the information elements IE. If an information element IE does not yet exist in the cache database, the caching entity creates a new entry for this information element IE. Furthermore, it updates the information for those information elements IE for which entries in the cached database already exist but for which the values expired. After this update process the caching entity prepares an IS response MIH frame and forwards the result to the information requesting communication node 1.

Many modifications and other embodiments of the invention set forth herein will come to mind the one skilled in the art to which the invention pertains having the benefit of the teachings presented in the foregoing description and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

C l a i m s

1. A method for providing media independent handover (MIH) services to a communication node, preferably according to the IEEE 802.21 standard, wherein the communication node (1 ) is attached to a network via a Point of Attachment (PoA) which has access to an information database (IS) via appropriate network entities, and wherein information, upon a respective request from the communication node (1 ), is forwarded from the information database (IS) to the communication node (1), c h a r a c t e r i z e d i n that a caching functionality is enabled at at least one network entity - caching entity - on the path between the communication node (1) and the information database (IS), wherein the information forwarded from the information database (IS) to the communication node (1) is stored at the caching entity.

2. The method according to claim 1 , wherein the caching functionality is enabled at the Point of Attachment (PoA) of the communication node (1 ).

3. The method according to claim 1 or 2, wherein the communication node (1) is a mobile node or a network entity.

4. The method according to any of claim 1 to 3, wherein the Point of Attachment (PoA) is an Access Point, a Node B, or another entity adapted to the properties of the communication node (1 ).

5. The method according to any of claim 1 to 3, wherein the caching functionality is implemented in such a way that information that the information database (IS) sends back to information requesting communication nodes (1 ) is stored in a cache database at the caching entity.

6. The method according to claim 5, wherein the information before being stored in the cache database at the caching entity is divided into individual information elements (IE).

7. The method according to claim 6, wherein each information element (IE) is assigned an individual code.

8. The method according to claim 6 or 7, wherein an expiration period is defined for each information element (IE) giving the time period the respective information element (IE) will be stored in the cache database at the caching entity.

9. The method according to any of claim 6 to 8, wherein an area of validity is defined for each information element (IE) giving the area for which the respective information element (IE) possesses validity.

10. The method according to claim 8 or 9, wherein the expiration period and/or the area of validity are parameters which are configurable for each information element (IE) separately.

11. The method according to any of claim 6 to 10, wherein the caching entity, upon receipt of an information request from a communication node (1), checks if the cache database contains a valid value of each specific information element (IE) requested by the communication node (1).

12. The method according to claim 11 , wherein the caching entity forwards values of those requested information elements (IE) to the requesting communication node (1) for which the cache database contains a valid value.

13. The method according to claim 11 or 12, wherein the caching entity refreshes the values of those requested information elements (IE) for which the cache database does not contain a valid value by requesting the respective values from the Information Server.

14. The method according to any of claim 11 to 13, wherein the caching entity, in the context of the validity check of a value of an information element (IE), checks if the request originates from a communication node (1 ) within the area of validity defined for the requested information element (IE).

15. The method according to any of claim 6 to 14, wherein the storage of information elements (IE) in the cache database is arranged according to configurable criteria.

16. The method according to any of claim 6 to 15, wherein the information elements (IE) stored in the cache database are ordered according to their amount of being requested.

17. The method according to any of claim 1 to 16, wherein the caching entity is operated in a proactive manner.

18. The method according to any of claim 1 to 17, wherein the MIH service is an Information Service, a Command Service, an Event Service, and/or any other Service.

19. The method according to claim 18, wherein the Information Service provided by the information database includes information related to the neighbouring networks of the communication node (1).

20. The method according to claim 18 or 19, wherein the Command Service includes an enforced handover.