WO2015007316A1

WO2015007316A1 - Advanced access network selection methods, devices and computer programs

Info

Publication number: WO2015007316A1
Application number: PCT/EP2013/065180
Authority: WO
Inventors: Fabian Castro Castro; Angel Navas Cornejo; Miguel CRUZADO GUTIERREZ
Original assignee: Telefonaktiebolaget L M Ericsson (Publ)
Priority date: 2013-07-18
Filing date: 2013-07-18
Publication date: 2015-01-22

Abstract

In a telecommunication network, a terminal device (100) sends, to a network node (200) hosting an access network discovery and selection function (ANDSF), time zone information (50a), i.e. information about the terminal device's (100) current time zone. Then, the ANDSF node (200) determines access network policies based on the time zone information (50a). In a second solution, the terminal device (100) sends, to the ANDSF node (200), local clock time information (50b), i.e. information (50b) about the terminal device's (100) local clock time; the ANDSF node (200) determines (s40b) time zone information for the terminal device (100) based the received local clock time information (50b) and local clock time information of the ANDSF node (200); and the ANDSF node (200) determines access network policies based on the time zone information. The invention also relates to terminal devices, network nodes and computer programs for carrying out the above- described methods.

Description

[Title]

Advanced access network selection methods, devices and computer programs

[Technical field]

The present invention relates to methods for access network selection in a telecommunication network. The invention also relates to devices for participating in access network selection procedures in a telecommunication network, and to computer programs therefor.

[Background]

The deployment of radio access network technologies in parallel to cellular networks, combined with the widespread use of multimode mobile communication devices, has created the opportunity to offload mobile communications to, for example, wireless access networks (such as: wireless local area networks -also known as "Wi-Fi" networks- and wireless metropolitan area networks -also known as "WiMax" networks) in order to alleviate congestion in cellular networks. Many wireless LANs have been deployed in airports, train stations, restaurants, hotels, libraries, campuses, etc., and their number is growing. At the same time, the data traffic going through mobile communication networks is growing as well. Efforts have been made to standardize, at least to a certain extent, cellular and wireless LANs interworking procedures, such as for example the procedures for initiating the offloading of a communication.

In that context, entities hosting an access network discovery and selection function (ANDSF) are used to provide terminal devices with rules to discover and select access networks, to prioritize particular access networks and to manage the corresponding connections, so as to efficiently implement the offloading of a communication to a 3GPP or non-3GPP access network.

The ANDSF functionality is notably discussed in (i) 3GPP TS 23.402 V12.0.0 (2013-03), "Technical Specification; 3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Architecture enhancements for nonSGPP accesses (Release 12)", (hereinafter referred to as reference [1]), see notably subclause 4.8.2.1 ; (ii) 3GPP TS 24.302 V12.0.0 (2013-03), "Technical Specification; 3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; Access to the 3GPP Evolved Packet Core (EPC) via non-3GPP access networks; Stage 3 (Release 12)" (hereinafter referred to as reference [2]), see notably subclause 6.8.2.3 and Annex A2; and (iii) 3GPP TS 24.312 V12.0.0 (2013-03); "Technical Specification; 3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; Access Network Discovery and Selection Function (ANDSF) Management Object (MO) (Release 12)" (hereinafter referred to as reference [3]), which provides details of the data that can be managed by the messages exchanged between an ANDSF and a UE. References [1], [2] and [3] are available on the 3GPP web site from the following URLs: httpJ/www.3gpp.org/ftp/Specs/html-info/23402.htm ;

http://www.3gpp.org/ftp/Specs/html-info/24302.htm ; and

http://www.3gpp.org/ftp/Specs/html-info/24312.htm respectively.

It is desirable to make sure that the rules and policies for selecting access networks are correctly implemented by terminal devices. In other words, a core network of a wireless communication system has to be accessed via one of a plurality of different access networks in compliance with the rules decided by an ANDSF entity.

[Summary]

To meet or at least partially meet the above-mentioned goals, methods, terminal devices and network nodes according to the invention are defined in the

independent claims. Particular embodiments are defined in the dependent claims.

The invention covers two solutions to the same technical problem. These two solutions are hereinafter referred to as "solution A" and "solution B" respectively.

In one embodiment (in accordance with solution A), a method is carried out in a telecommunication network and comprises the following steps. A terminal device sends, to a network node hosting an ANDSF, said network node being hereinafter referred to as "ANDSF node", information about the time zone associated with the geographical area in which the terminal device is located, said information being hereinafter referred to as "time zone information". Then, the ANDSF node

determines, based on the time zone information, at least one access network policy.

In one embodiment (in accordance with solution B), a method is carried out in a telecommunication network and comprises the following steps. A terminal device sends, to an ANDSF node, information about the local clock time of the terminal device, said information being hereinafter referred to as "local clock time information". The ANDSF node then determines information about the time zone associated with the geographical area in which the terminal device is located, said information being hereinafter referred to as "time zone information", based on the difference between the local clock time information received from the terminal device and local clock time information of the ANDSF node. Thereafter, the ANDSF node determines, based on the time zone information, at least one access network policy.

These two solutions enable an ANDSF node to take into account the time zone where a terminal device is located to determine which access network policies the terminal device should follow. This is especially useful to correctly enforce time- dependent access network policies when terminal devices may be in a time zone differing from the time zone where the ANDSF node is located.

In one embodiment (in accordance with solution A), a method is carried out by a terminal device. The method comprises sending, to an ANDSF node, information about the time zone associated with the geographical area in which the terminal device is located, said information being hereinafter referred to as "time zone information".

In one embodiment (in accordance with solution B), a method is carried out by a terminal device. The method comprises sending, to an ANDSF node, information about the local clock time of the terminal device, said information being hereinafter referred to as "local clock time information".

In one embodiment (in accordance with solution A), a method is carried out by an ANDSF node. The ANDSF node receives, from a terminal device, information about the time zone associated with the geographical area in which the terminal device is located, said information being hereinafter referred to as "time zone information". The ANDSF node then determines, based on the received time zone information, at least one access network policy.

In one embodiment (in accordance with solution B), a method is carried out by an ANDSF node. The ANDSF node receives, from a terminal device, information about the local clock time of the terminal device, said information being hereinafter referred to as "local clock time information". The ANDSF node then first determines information about the time zone associated with the geographical area in which the terminal device is located, said information being hereinafter referred to as "time zone information", based on the difference between the local clock time information received from the terminal device and local clock time information of the ANDSF node. Thereafter, the ANDSF node determines, based on the time zone

information, at least one access network policy. The invention also relates, in one embodiment (in accordance with solution A), to a terminal device comprising a so-called time zone information sending unit. The time zone information sending unit is configured for sending, to an ANDSF node, information about the time zone associated with the geographical area in which the terminal device is located, said information being hereinafter referred to as "time zone information".

The invention further relates, in one embodiment (in accordance with solution B), to a terminal device comprising a so-called local clock time sending unit. The local clock time sending unit is configured for sending, to a network node hosting an ANDSF node, information about the local clock time of the terminal device, said information being hereinafter referred to as "local clock time information".

The invention yet further relates, in one embodiment (in accordance with solution

A) , to a network node hosting an ANDSF, i.e. to a so-called ANDSF node. The ANDSF node comprises a so-called time zone information receiving unit and a so- called access network policy determining unit. The time zone information receiving unit is configured for receiving, from a terminal device, information about the time zone associated with the geographical area in which the terminal device is located, said information being hereinafter referred to as "time zone information". The access network policy determining unit is configured for determining, based on the received time zone information, at least one access network policy.

B) , to a network node hosting an ANDSF, i.e. to a so-called ANDSF node, which is as follows. The ANDSF node comprises a so-called local clock time information receiving unit, a so-called time zone information determining unit, and a so-called access network policy determining unit. The local clock time information receiving unit is configured for receiving, from a terminal device, information about the local clock time of the terminal device, said information being hereinafter referred to as "local clock time information". The time zone information determining unit is configured for determining information about the time zone associated with the geographical area in which the terminal device is located, said information being hereinafter referred to as "time zone information", based on the difference between the local clock time information received from the terminal device and local clock time information of the ANDSF node. The access network policy determining unit is configured for determining at least one access network policy, based on the time zone information. The invention also relates to a system of terminal device(s) and network node(s) as described above, implemented for example using a set of programmed computers or the like.

The invention also relates to computer programs, computer program products and storage mediums comprising computer-readable instructions configured, when executed on network nodes or terminal devices, to cause the network nodes or terminal devices to participate in a method according to any one of the above- described embodiments, or to implement the functions of a network node or terminal device according to any one of the above-described embodiments.

[Brief description of the drawings]

Embodiments of the present invention shall now be described, in conjunction with the appended figures, in which: Figs. 1a and 1b are message sequence charts of methods in two embodiments of the invention, according to solutions A and B respectively;

Figs. 2a and 2b are message sequence charts of methods involving the

transmission of access network policies to a terminal device, in two embodiments of the invention, according to solutions A and B respectively;

Fig. 3 schematically illustrates a non-roaming architecture within an Evolved Packet System (EPS), to illustrate the context in which some embodiments of the invention may be put into practice;

Fig. 4 schematically illustrates the control of UE access through an ANDSF node, to illustrate the context in which some embodiments of the invention may be put into practice; Fig. 5 schematically illustrates a time-dependent access network policy that may be decided by an ANDSF node, to illustrate problems that some embodiments of the invention address; Fig. 6 is a message sequence chart involving a terminal device and an ANDSF node, to illustrate problems that some embodiments of the invention address;

Fig. 7 is a message sequence chart of a method in one embodiment of the invention;

Fig. 8 is a schematic diagram of an exemplary implementation of a terminal device according to one embodiment of the invention; Figs. 9a and 9b schematically illustrate terminal devices in two embodiments of the invention, according to solutions A and B respectively;

Figs. 10a and 10b schematically illustrate terminal devices each involving an access network policy receiving unit, in two embodiments of the invention, according to solutions A and B respectively;

Figs. 11a and 11b schematically illustrate ANDSF nodes, i.e. network nodes hosting an ANDSF, in two embodiments of the invention, according to solutions A and B respectively;

Figs. 12a and 12b schematically illustrate ANDSF nodes each involving an access network policy sending unit, in two embodiments of the invention, according to solutions A and B respectively; and Fig. 13 schematically illustrates the structure of an ANDSF management object (MO) in one embodiment of the invention.

[Detailed description]

The present invention shall now be described in conjunction with specific

embodiments. These specific embodiments serve to provide the skilled person with a better understanding, but are not intended to in any way restrict the scope of the invention, which is defined by the appended claims. A list of abbreviations and their meaning is provided at the end of the detailed description. Fig. 1a is a message sequence chart of a method in one embodiment of the invention, according to solution A.

In step s20a, a terminal device 100 sends s20ai, to an ANDSF node 200, information 50a (hereinafter "time zone information" 50a) about the time zone associated with the geographical area in which the terminal device 100 is located, and the ANDSF node 200 receives s20a₂ the time zone information 50a.

Terminal device 100 knows (or obtains) its time zone because the network (such as for example the serving PLMN) typically provides this information to the terminal device 100, which can store and use this information. Further information in that respect can for example be found in 3GPP TS 22.042 V11.0.0 (2012-09),

"Technical Specification; 3rd Generation Partnership Project; Technical

Specification Group Services and System Aspects; Network Identity and TimeZone (NITZ); Service description; Stage 1 (Release 11)", see for example clause 1 ("Scope") and subclause 6.1 ("Transfer of NITZ information").

The time zone information 50a may for example be transmitted using a format "+/- hh" or "+/-hh:mm" (e.g. "+04") to convey information about the difference between the terminal device's 100 local time and the UTC (Coordinated Universal Time) of the day. Time zone information 50a may also be transmitted using an extended format comprising both the time zone of terminal device 100 and its local time. For example, the format may be "hh:mm:ss:±hh:mm" (e.g.: "15:27:46+04:00). The time zone information 50a may be transmitted in a message, i.e. a set of bits forming a packet which can be transmitted over a communication network. The message may also be transmitted through a series of packets. The time zone information 50a may for example be transmitted in an IP packet. The time zone information 50a may be transmitted from terminal device 100 to ANDSF node 200 through one or more intermediate network nodes (not illustrated on Fig. 1a).

After receiving s20a₂ the time zone information 50a, ANDSF node 200 determines s60 access network policies based on the time zone information 50a, i.e. taking into account time zone information 50a. The access network policies are determined for the terminal device 100 from which the time zone information originates.

Any measures or procedures may be taken to enforce the access network policies on terminal device 100 from which the time zone information originates (not illustrated on Fig. 1a). For example, access network policies may be transmitted to terminal device 100 for enforcement (this will be explained with reference to Fig. 2a), or the transmission may be delayed until the policies become relevant.

Alternatively, or additionally, the policies may be transmitted to one or more network nodes in the vicinity of terminal device 100 for enforcement. Terminal device 100 may be any type of communication terminal (or user equipment (UE), or user terminal) such as, for example, a mobile phone, a smartphone, a laptop, a desktop computer, a tablet PC, a gaming device, a fixed telephone, etc. In one embodiment, terminal device 100 is a multimode wireless communication device.

In one embodiment, terminal device 100 is a device which operation is driven by a human user. In another embodiment, terminal device 100 is a machine-to-machine (M2M) communications device. In short, a M2 communications device is self- operable and does not require a human operating the device for communicating with a telecommunications system. An example of a M2M terminal is a device comprising a sensor metering a certain parameter (e.g. temperature, electric consumption, etc.) and communication means for transmitting the metered value e.g. at certain intervals. The term "terminal device" is herewith used to refer indistinctly to devices operated by human users and to self-operated/autonomous devices (M2M). In particular, for the sake of simplicity, the abbreviation "UE" or the term "terminal device" is herewith used to refer indistinctly to a communications terminal operated by a human user or to a M2M communications device.

Embodiments of invention may apply to human-driven terminal devices as well as to M2M terminal devices.

ANDSF node 200 is a network node, i.e. a control server, from which access network policies determining the access network(s) to which a terminal device should attach are downloaded. An exemplary ANDSF node 200 is described in reference [1], subclause 4.8.2.1. An ANDSF node 200 may serve, i.e. cover, more than one time zone. For example, in the United States, a possible deployment may involve ANDSF servers on the East and West coasts for covering the whole country. The above considerations notably regarding terminal device 100 and ANDSF node 200 apply to all embodiments, such as for example the method of Fig. 1b.

Fig. 1b is a message sequence chart of a method in one embodiment of the invention, according to solution B. The method illustrated by Fig. 1b differs from the one illustrated by Fig. 1a in that, in Fig. 1a (embodiment of solution A), explicit time zone information is sent from terminal device 100 to ANDSF node 200, whereas, in Fig. 1b (embodiment of solution B), local clock time information is sent from terminal device 100 to ANDSF node 200, which then derives the time zone information of terminal device 100 by calculation. In particular, the method illustrated by Fig. 1b differs from the one illustrated by Fig. 1a as follows.

In step s20b, as illustrated in Fig. 1b, rather than sending time zone information to the ANDSF node 200, the terminal device 100 sends s20bi information 50b

(hereinafter "local clock time information" 50b) about the local clock time of terminal device 00. Local clock time information 50b may for example be transmitted using a format "hh:mm:ss" (e.g.: "15:27:46") to convey information about the local time on terminal device 100. The transmission of local clock time information 50b from terminal device 100 to ANDSF node 200 may be carried out in a similar manner as the transmission of time zone information 50a as explained with reference to Fig. a. Namely, local clock time information 50b may be transmitted in a message, i.e. a packet or a series of packets, such as for example IP packet(s). Local clock time information 50b may transit through one or more intermediate network nodes (not illustrated on Fig. 1b).

After receiving s20b₂ local clock time information 50b, ANDSF node 200 determines s40b information about the time zone associated with the geographical area in which terminal device 100 is located, i.e. time zone information for terminal device 100. The determination 40b is carried by computing (i.e., calculating) the difference between local clock time information 50b received from terminal device 100 (i.e., the local time reported by terminal device 100) and local clock time information of ANDSF node 200 (i.e., its own local time). ANDSF node 200 then determines s60 access network policies based on the determined time zone information, i.e. taking into account the time zone information computed in step s40b. The access network policies are determined for terminal device 100 from which the time zone information originates. Step s60 illustrated on Fig. 1b may be identical to step s60 illustrated on Fig. 1a, and the optional following steps may also be identical (i.e., measures/procedures may be taken to enforce the access network policies on terminal device 100).

Therefore, in accordance with embodiments of solutions A and B illustrated by Figs. 1a and 1b respectively, time-related, locally-specific information is transmitted s20a, s20b from terminal device 100 to ANDSF node 200. Therefore, ANDSF node 200 can decide access network policies applicable for terminal device 100 and the enforcement thereof in the telecommunication system will be correct, even when the access network policies are time-dependent and terminal device 100 is not in the same time zone as ANDSF node 200. It has been recognized by the inventors, on the one hand, that the time zone where a terminal device is located may differ from the time zone where the ANDSF node is located, and, on the other hand, that this situation may lead to the incorrect enforcement of rules decided by the ANDSF node. Indeed, the ANDSF node may establish that particular access network policies are to be enforced during a given time period, for example during peak hours. However, at the time when the ANDSF node sends new access network policies for enforcement by a terminal device at the beginning of the particular time period (for example at the beginning of the peak hours), this particular time period may have already begun or not yet begun, due to the time zone difference. Some embodiments of solutions A and B enable the time zone difference to be accounted for by the ANDSF node -and, thus, determining access network policy/ies based on the time zone of the terminal device-, without requiring the terminal device to send its current geographical coordinates to the ANDSF node (such procedure would require the terminal device to be equipped with a GPS receiver or the like, which would have to be enabled and kept active, thus substantially increasing the battery consumption). Embodiments of solutions A and B further dispense with the need for the ANDSF node to rely on a database containing a list of identifiers of all the available access network points of 3GPP and non-3GPP access networks (e.g. identifiers of WiFi access points, identifiers of 3GPP cells, etc) where the terminal device might theoretically attach, and the time zone in which these access network points are (setting up such a database would involve high maintenance costs). Some embodiments of solutions A and B are particularly advantageous in contexts wherein, e.g., the access network policies to be downloaded to terminal devices vary with time. For example, according to the access network policy, the terminal device may be required to change the access network to which it is attached from a first access network (e.g., a 3GPP UTRAN access network) to a second access network (e.g., a WLAN access network provided by a Wi-Fi hot-spot). The enforcing time may be used to alleviate congestions that might occur in some access networks (e.g. at traffic peak hours). In that respect, some embodiments of solutions A and B involve: (i) terminal device 100 sending s20a, s20b, to ANDSF node 200, information about its current (geographical) time zone and/or information about its local clock time, and (ii) ANDSF node 200 determining, based on the time zone information and/or local clock time information received from terminal device 100, access network policies that are to be sent to terminal device 100. This means that the access network policies sent to a terminal device in a first time zone may substantially differ from the policies that would be sent to the same terminal device if it was in a second time zone. Thus, access network policies can be correctly enforced by terminal devices taking into account their time zone, and congestion can be effectively alleviated in the access networks available to the terminal devices, even if located in a different time zone than the ANDSF node time zone.

In one embodiment, the step of determining s60, by ANDSF node 200, access network policies based on the time zone information (as illustrated for example by Figs. 1a and 1b) comprises selecting a type of access network to which terminal device 100 should attach. The selected type of access network may for example be a 3GPP access network (such as a GERAN, a UTRAN, or a E-UTRAN), or a non- 3GPP access network (such as a wireless LAN interoperable with IEEE 802.11 standards -also known as "WiFi"-, or a wireless MAN interoperable with IEEE 802.16 standards -also known as "WiMax"-). In one embodiment, the step of determining s60, by ANDSF node 200, access network policies based on the time zone information (as illustrated for example by Figs. 1a and 1b) comprises selecting one access network to which the terminal device 100 should attach. In one embodiment, the step of determining s60, by ANDSF node 200, access network policies based on the time zone information (as illustrated for example by Figs. 1a and 1b) comprises selecting a plurality of access networks, wherein the terminal device 100 should attach to one of the plurality of access networks. The access network policies may comprise a prioritized list of access networks, with higher-priority access networks, to which terminal device 100 should preferably attach, and lower-priority access networks.

In one embodiment, the step of determining s60 access network policies is further based on at least one of: (i) the time of the day; and (ii) congestion information associated with the access networks available in the geographical area in which terminal device 100 is located.

In one embodiment, the step of determining s60 access network policies comprises accessing a database (not illustrated on Figs. 1a and 1b) storing at least: (a) information identifying time zones; and (b) for each time zone, local time values identifying the time zone's peak hour time, and access network policies for the time zone's peak hour time. Said database may be an internal database, i.e. a database hosted on ANDSF node 200, or an external database, i.e. a database accessible by ANDSF node 200. Figs. 2a and 2b are message sequence charts of methods in two embodiments of the invention, which differ from the methods illustrated by Figs. 1 a and 1 b

respectively in that the method further comprises transmitting s80, from ANDSF node 200 to terminal device 100, access network policy information, i.e. information for enabling terminal device 100 to enforce the access network policies.

In one embodiment, the access network policy information is transmitted s80, from ANDSF node 200 to terminal device 100, on a just-in-time basis, i.e. not long in advance but only when the access network policy is about to become applicable, i.e. for direct applicability upon reception. This reduces the signalling flow since access network policy information transmitted in advance of their applicability may become obsolete or useless if, in the meantime, terminal device 100 has moved to another time zone or has been switched off. This also simplifies the signalling since it is therefore unnecessary to send, to terminal device 00, timing information along with the access network policy information.

Now, to further understand the advantages of the invention, the context in which some embodiments of the invention have been developed and may be put into practice will be explained in more detail (notably with reference to Figs. 3 and 4), followed by the description of further embodiments.

The term "converged network" refers to telecommunications systems with different kinds of access networks (e.g. fixed access networks, 3GPP radio access networks and non-3GPP radio access networks) which share the same core network system infrastructure (e.g. telecommunication nodes shown in the upper part of Fig. 3). This implies -e.g. for a user subscribed to a PLMN operator- a single subscription with a telecom operator (i.e. his "Home PLMN", HPLMN) which is access network independent. Examples of 3GPP access network are: GERAN, UTRAN or E- UTRAN radio access networks. Examples of non-3GPP access networks are: Wi-Fi or WiMax radio access networks.

Mobile communication networks are experiencing a fast increase in data traffic. In this context, the use of policy control and deep packet inspection (DPI) have become important, allowing operators to control the network resources and assign different services and bandwidth to the subscribers according to their subscription. 3GPP TS 23.203 V12.0.0 (2013-03), "Technical Specification; 3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Policy and charging control architecture (Release 12)" (hereinafter referred to as reference [4]) discloses a policy and charging control (PCC) architecture for 3rd generation communications systems. Among other, the PCC architecture comprise two kind of nodes: a PCEF (a policy enforcement point, PEP) routing data packets to/from user terminals, and a PCRF (a policy decision point, PDP) deciding the QoS policy rules to be applied for a particular communication of a user terminal in a PCEF (the so-called "PCC rules" in the terminology of reference [4]).

Meanwhile, operators supporting both wired and wireless accesses have recently shown an increased interest in the area of fixed-mobile convergence, specifically within the context of policy control. These operators wish to offer the same service across fixed and mobile accesses. A converged architecture is therefore needed that can best support the "quest for QoS" in mobile and fixed access, with the goal to provide users with seamless services across fixed and mobile environments. This led to the need of having a common policy control server able to control the resources of both accesses.

The PCC architecture for a telecommunications system involves a so-called

Evolved 3GPP Packet Switched core network system (EPC) that can be accessible by terminals using both 3GPP access networks (e.g. GERAN/UTRAN/E-UTRAN) and non-3GPP access networks (e.g. Wi-Fi, WiMax). The resulting

telecommunication system is referred to as an Evolved Packet System (EPS). This access network flexible architecture makes it possible to apply policy and charging control to any kind of data session (IP-CAN session) established by a user terminal via 3GPP access networks and/or via any non-3GPP access networks, such as via Wi-Fi or WiMax accesses. Reference [1] discloses for example details of such architecture. Fig. 3, which corresponds to figure 4.2.2-1 of reference [1],

schematically illustrates an exemplary non-roaming architecture within an Evolved Packet System (EPS). An IP-CAN session is an IP session existing between a communications terminal, referred herein also as terminal device or user equipment (UE), and the network. The session is identified by an IP address.

The offloading of mobile traffic to, for example, a Wi-Fi network (i.e. via WLAN access points) can be used by operators to offer a higher bandwidth and a better service to end users when the performance or quality that can be offered by e.g. a 3GPP network is not enough for the services they want to access.

Besides, some operators are considering Wi-Fi as a coverage extension to their networks, complementing the radio coverage by means of Wi-Fi access points, not only in their home networks but also when roaming. This may involve automatically connecting subscribers to Wi-Fi hotspots via SIM authentication when roaming, obviating the need for subscribers to launch a client or enter a username and password to gain Wi-Fi access. Therefore, non-3GPP technologies such as Wi-Fi are increasingly used by mobile operators not only for domestic offload to ease congestion but also in a roaming scenario to offer better roaming services and a better user experience to their subscribers. ANDSF entities are control nodes operable to send, to a terminal device, access network policy messages comprising access network policy information. Said access network policy messages are usable by the terminal device to enable it to e.g. change a data connection from a first access network to which the terminal device is currently connected (e.g. a data connection established between the terminal device and a 3GPP or non-3GPP access network) to a second access network (i.e. a further access network to which the terminal device can connect). In summary, the ANDSF is an example of a control node operable to control access by a terminal device to access networks. The ANDSF contains data management and control functionality necessary to provide network discovery and selection assistance data to the terminal device over the S14 interface as per operators' policy. Two modes of operation are defined over the S14 interface for transferring access network policy information from an ANDSF to a terminal device: a) A "pull" mode allows the terminal device to fetch access network discovery and selection policies from the ANDSF. This is typically implemented with OMA Device Management, bound to HTTP, and carrying the ANDSF policies. b) A "push" mode allows the ANDSF to indicate to one or more terminal devices that they should fetch policies from the ANDSF. The initial push message from the ANDSF and the terminal device is implemented with a WAP Push SMS.

The information may for example be transferred between the terminal device and ANDSF entity in accordance with the OMA Device Management (OMA DM) protocol defined by the Open Mobile Alliance (OMA) for example in "Enabler Release Definition for OMA Device Management; Approved Version 1.2 - 09 Feb 2007; Open Mobile Alliance; OMA-ERELD-DM-V1_2-20070209-A" (available from http://technical.openmobilealliance.org/ftp/publi^

MA-ERELD-D -V1_2-20070209-A.zip ), hereinafter referred to as reference [5].

Chapter 5 of reference [5] lists the OMA specifications applicable to OMA Device Management (OMA DM) according to its version 1 .2. In turn, the ANDSF

Management Object (MO) is specified in reference [3] (e.g. within the figures listed under reference [3], subclause 4.2).

The ANDSF responds to a terminal device's requests for access network discovery information (pull mode operation) and is able to initiate data transfer to the terminal device (push mode operation), based on network triggers (e.g. timers, network condition information obtained by the ANDSF, etc.) or as a result of previous communication with the terminal device. There are three types of information provided by the ANDSF, i.e. the inter-system mobility policy, the access network discovery information and the inter-system routing policy. The ANDSF may provide all types of information or only one of them:

Inter-system mobility policy (ISMP):

The ISMP is an access network policy comprising a set of operator-defined rules and preferences that affect the inter-system mobility decisions taken by a terminal device. The terminal device uses the inter-system mobility policy when it can route IP traffic only over a single radio access interface at a given time (e.g. is not IFOM-capable or its IFOM capability is disabled)

Access network discovery information:

Upon a request from a terminal device, the ANDSF may provide a list of access networks available in the vicinity of the terminal device for all the access technology types requested by the terminal device (if any requested).

Inter-System Routing Policy (ISRP):

The ISRP is also an access network policy. The ANDSF may provide, to the terminal device, a list of Inter-System Routing Policies that are capable of routing IP traffic simultaneously over multiple radio access interfaces. The terminal device uses the inter-system routing policies when it can route IP traffic simultaneously over multiple radio access interfaces (e.g. it is an IFOM-capable terminal device with the IFOM capability enabled or a

MAPCON-capable terminal device with the MAPCON capability enabled) in order to meet the operator routing / offload preferences. Fig. 4 schematically illustrates an exemplary access control via an ANDSF node and the interfaces (i.e., reference points) that may be involved between a terminal device and an ANDSF node and between the ANDSF node and a user data repository (UDR). Let us now discuss some of the problems addressed by embodiments of the invention, for further understanding the context in which some embodiments of the invention have been developed.

An ANDSF node may take access selection decisions based on different criteria, such as for example:

Based on location information: A subscriber attached to a 3GPP access network is instructed by the ANDSF node via the S14 reference point to select Wi-Fi as access network when the subscriber moves to certain cell or area.

Based on congestion: Selection of Wi-Fi as access network when the subscriber moves to a congested cell or selection of 3GPP access when Wi- Fi is congested.

Based on subscription information.

- Based on time: ANDSF selects between 3GPP access and Wi-Fi access depending on time. For example, Wi-Fi is to be selected only during certain periods of time during which it is known that congestion of 3GPP access is foreseen, e.g. peak hours. For time-dependent policies, it has been recognized that ANDSF node does not receive adequate information to take the right decision in areas where there are different time zones. This is very relevant for countries with different time zones and also in roaming scenarios between countries with different time zones. For example, let us consider a situation in which the terminal device is located in an area that has a different time zone than the ANDSF area.

The operator intention is that ANDSF renews policies for specific subscribers at specific time, e.g. peak hour. Let us say that the peak hour extends matches the lunch time in a whole country. During peak hour, the operator steers users to Wi-Fi access and out of the peak hour the user is steered to 3GPP access networks. This situation is schematically illustrated by Fig 5. To implement this, an ANDSF can send -e.g. at the beginning of the peak hour- access network policies to a plurality of terminal devices, so that these terminal devices prioritize their access network selection to e.g. try to select Wi-Fi access networks in first place and then -e.g. in case of failure- to select 3GPP access networks; and to send later -e.g. at the end of the peak hour- new access network policies that e.g. reverse the network selection order priority above (i.e. first 3GPP access network and then, as a second option, non-3GPP access networks, such as Wi-Fi access networks).

However, conventional ANDSF nodes are not aware of the terminal devices' time zone, so that time-based policies may be incorrectly enforced by the terminal devices.

In that respect, a conventional ANDSF may -but it is not required to- send

"TimeOfDay" information element(s) associated to access network policies transmitted to a terminal device. Such information element(s) can specify start and/or stop times for enforcing, by the terminal device, the access network policies received from the ANDSF, and to be interpreted by the terminal device according to its local time (see reference [3], subclause 5.4.47, second paragraph). However, configuring a conventional ANDSF to send access network policies to a plurality of terminals using the "TimeOfDay" information element(s) is complex. Firstly, access network roaming conditions for accessing 3GPP and/or non-3GPP access networks can vary depending on the users of a certain telecom operator (e.g. depending on the country/zone where they are roaming with their terminal device(s), the available options may vary). Moreover, the behavioral network conditions can vary along different countries/zones (e.g. the so-called peak hours do not necessarily exactly match all countries/zones, and can also vary differently in different periods of the year). Furthermore, some terminal devices might not support this kind of time-based application for access network selection and/or ignore it. Consequently, it is being envisaged that an ANDSF just sends access network policies to the terminal devices without attaching time information to the policies (i.e., the policies are delivered on a just-in-time basis, not long in advance). In such a situation, an ANDSF sends access network policy information to terminal devices in certain circumstances; for example, when a UE communicates with the ANDSF e.g. after it has been turned on, or when the ANDSF decides (e.g. based on its local time and configuration) that new/updated access network policies are to be downloaded (pushed) to a plurality of terminal devices.

Fig. 6 is a message sequence chart illustrating problems that some embodiments of the invention address. In the exemplary situation of Fig. 6, the ANDSF is configured with information about a peak hour from 1 1 :00h to 12:30h. The ANDSF determines the access network policies to be sent to a UE according to its local time. The UE- ANDSF communication is implemented through a so-called S14 interface.

(step 1) The terminal device (referred to as UE in Fig. 6) attaches to the

network before the peak hour (e.g. let us assume at 10:00 local time of the ANDSF) and establishes an OMA DM session towards the ANDSF requesting access network policies (pull mode). The UE provides the UE_Location (see in that respect reference [3],

subclause 5.6), device information and policy request indication.

(step 2) Once the ANDSF authenticates the subscriber, the ANDSF

determines access network policies that are to be sent to the UE according to the subscriber profile data of the UE and the provided UE_Location. For example, the access network policies may be:

Outside peak hour:

Priority 1 : 3GPP access networks; and

Priority 2: Wi-Fi access networks.

Within peak hour:

Priority 1 : Wi-Fi access networks; and

Priority 2: 3GPP access networks.

(step 3) The ANDSF sets and starts an internal timer configured to time-out at the beginning of the peak hour, so that the ANDSF is to be able to push new access priorities to the UE at that time. (However, as mentioned earlier, the ANDSF has its own time clock and is not aware of the time difference with the UEs to which the ANDSF has to send the corresponding access network policies). (step 4) As a result, the ANDSF stores internally a trigger to contact the UE at a specific time (i.e. ANDSF local time), that does not necessarily coincide with the beginning of the peak hour of the area where the UE is located. If the ANDSF stores such a trigger, this is according to ANDSF local time that may differ from UE local time.

(step 5) As a result of the request for access network policies received from the UE in step 1 (i.e. outside the peak hour, according to ANDSF local time), the ANDSF responds to the UE and provides the UE with the policies previously determined in step 2. According to this example, the access network policies sent to the UE in step 5 as a reply to its request received in step 1 (i.e.: according to the example, the ANDSF considers the time in which it received the communication from the UE -step 1- as outside the peak hour) may comprise:

Priority : 3GPP access networks; and

Priority 2: Wi-Fi access networks.

As a result, the UE prioritizes an attempt to attach to 3GPP access networks (priority 1) and, then, e.g. only in case of failure, to Wi-Fi access network (priority 2).

(step 6) At the beginning of the peak hour, the ANDSF (about 1 :00 ANDSF's local time) should push new policies to the terminal to change the access to 3GPP access networks. The timer set in step 3 can be used for this purpose (i.e. its time out). (However, because of the problem previously described, the time trigger internally used in the ANDSF in step 3, may not coincide with the beginning of the peak hour, UE local time. This may provoke the ANDSF to initiate the push notification towards the UE at a wrong time).

(step 7) The ANSDF sends an SMS to the UE for it to establish a new OMA

DM session in order to renew access network policies in the UE.

According to this example, the access network policies to be further sent to the UE in this step (i.e. at the start of, or during, the Peak hour) comprise:

Priority 1 : Wi-Fi access networks; and

Priority 2: 3GPP access networks. The ANDSF can later transmit to the UE -e.g. at the end of its configured peak hour information, 12:30h- the corresponding access network information policies.

According to the example, the ANDSF would then send, to the UE, access network policies similar to the ones sent on step 5 (i.e. policies for outside the peak hour). To accomplish this, the ANDSF can start a timer at the sending of step 7, or can start a (second) timer at step 3 that should time-out at the end of the peak hour. These steps are not illustrated by Fig. 6. The hypothetical ANDSF of Fig. 6 determines access network policies to be sent to a UE in accordance with its local time. Thus, the access network policies sent to the UE in the above example would be fine and would contribute to lower the

congestion of 3GPP networks at peak hours provided that the UE is within the same time zone as the ANDSF, but otherwise would not contribute to this purpose and could even be counterproductive.

One solution to the above problems is to store in a database accessible to the ANDSF the identifiers of all the access points of all the access networks that the UE could access to and, for each access point, the associated time zone. This is complex and may be costly in terms of maintenance costs due to the number of available access points. Another solution is to send, by the UE, geographical coordinates (such as GPS coordinates) from which the ANDSF can deduce the UE current time zone. This requires the UE to be equipped with a GPS receiver or the like, which has to be enabled and kept active, thus substantially increasing the battery consumption.

Some embodiments of the invention address the above-described problems with solutions that involves: (i) a terminal device 100 sending s20a, s20b, to an ANDSF node 200, information about its current time zone (and/or its local time); and (ii) the ANDSF node 200 determining s60 access network policies to be sent to terminal device 100 based on the time zone information received from terminal device 100 (an embodiment of solution A, as illustrated notably by Fig. 1a) or based on the time zone information computed by ANDSF node 200 based on the time difference between the local time reported by terminal device 100 and the ANDSF node's 200 own local time (an embodiment of solution B, as illustrated notably by Fig. 1b).

Accordingly, the access network policies sent to a terminal device 100 in a first time zone may substantially differ from the policies that would be sent to the same terminal device 100 in a second time zone. Correct access network policies are sent to terminal devices 100, contributing to properly controlling the traffic to the access networks and preventing the congestion thereof.

Some embodiments of the invention thus involve a terminal device 100 informing an ANDSF node 200 about the time zone of the geographical area where terminal device 100 is located.

Some embodiments of the invention also involve extending the S14 interface defined between terminal device 100 and ANDSF node 200 to convey time zone information of terminal device 100. ANDSF node 200 decides access network policies (ISMP and/or ISRP) to be sent to terminal device 100 based on the time zone information received from terminal device 100.

Some embodiments of the invention involve enriching the S14 interface so that terminal device 100 can provide ANDSF node 200 with time zone information and ANDSF node 200 can adapt time-dependent access network policy information to the terminal device 100 time zone.

In one embodiment, the information conveying the time zone of terminal device 100 is inserted as a new sub-element within the leaf information node named

"UE_Location" of the ANDSF Management Object (MO) defined in figure 4.2.4 of reference [3]. One exemplary way of implementing this embodiment is

schematically illustrated by Fig. 13, showing an ANDSF MO with "TimeZone" information. Accordingly, terminal device 00 preferably attaches this new

information element (named "TimeZone" in Fig. 13) when it sends a request for access network policies to ANDSF node 200. There are different ways according to which the coding (i.e., format) of this new element "TimeZone" may be achieved, for example as explained above with reference to Fig. 1a (time zone information sent by terminal device 100) and Fig. 1b (local clock time information sent by terminal device 100 based on which ANDSF node 200 computes the time zone information).

Fig. 7 schematically illustrates a terminal-to-ANDSF communication through S14 interface comprising time zone information sent by terminal device 100, in one embodiment of the invention. In particular, Fig. 7 illustrates a scenario which is similar to the one described earlier with reference to Fig. 6 in the sense that the same exemplary peak hour values (i.e., peak hour from 11 :00h to 12:30h) and policies are configured within ANDSF nodes 200. The problems described with reference to Fig. 6 are solved in Fig. 7 by making use of the "TimeZone" information provided by terminal device 100. For simplicity, in this example, it is considered that the ANDSF node time zone is UTC+0.

(step 1) Terminal device 100 attaches to the network before the peak hour (i.e.

according to local time on ANDSF node 200) and establishes at that point in time an OMA DM session towards ANDSF node 200 requesting access network policies. In this example, let us assume that terminal device 100 establishes this communication with ANDSF node 200 at 10:05, local time on ANDSF node 200. Terminal device 100 provides the UE_Location information, device information, policy request indication and time zone information in respect to its local time zone (new element "TimeZone" cited above), as illustrated in Fig. 7 by the arrow labelled "HTTP POST - Policy request, UE_Location, Devjnfo, TimeZonelnfo". In this example, let us further assume that the terminal device time zone (either: expressly indicated, or obtained by ANDSF node 200 based on the terminal device reported local time) is UTC+1. Thus, ANDSF node 200 determines that terminal device 100 is currently within the peak hour because the terminal device local time is 11 :05. Step 1 of Fig. 7 corresponds to steps s20a and s20b of Figs. 1a and 1b respectively.

(step 2) ANDSF node 200 can then derive (i.e., determine) access network policies to be sent to terminal device 100, not only taking into account the terminal device's subscriber profile data and/or the terminal device current location, but also the terminal device time zone (i.e. "TimeZone" information received from terminal device 100), as illustrated in Fig. 7 by the box labelled "ANDSF derives policies based on subscription type, UE_Location, and TimeZone". Step 2 of Fig. 7 corresponds to step s60 of Fig. 1a and steps s40b and s60 of Fig. 1 b. The policies configured in ANDSF node 200 may be similar to the ones described earlier in respect to step 2 of Fig. 6.

However, the access network policies determined by ANDSF node 200 may substantially differ from the ones derived in the scenario illustrated in respect to Fig. 6 if the time zone of terminal device 100 is not the same as the time zone of ANDSF node 200. Namely, in the present case, as explained earlier, terminal device 100 is considered to be within the peak hour. (steps 3-4) ANDSF node 200 has its own time clock and receives the time zone information from terminal device 100 (or, if terminal device 100 only reports its local clock time, ANDSF node 200 determines the time zone information based on the differences between its own local clock time and the local clock time reported by terminal device 100). Thus,

ANDSF node 200 can take into account, and store, the time difference between the ANDSF time and the received UEJocation time

("TimeZone"). As a result, ANDSF node 200 can store internal trigger(s) (e.g. by means of one or more timers) for monitoring the peak hour, which are set (as opposed to the example of Fig. 6) not according to the local time of ANDSF node 200, but according to terminal device local time (i.e. considering the offset according to the time zone received from terminal device 100). This illustrated in Fig. 7 by the box labelled

"ANDSF stores information about the UE time zone and sets a trigger for the busy hour" and by the hourglass-like icon.

In this example, ANDSF node 200 may start a timer for 1 hour 25 minutes, so that the timer may be programed to lapse when terminal device 100 exits the peak hour according to its time zone (namely, at 12:30 local time of terminal device 100, and at 11 :30 local time of ANDSF node 200). (step 5) ANDSF node 200 provides the access network policy (or policies) previously computed in step 2. For example, taking into account that, according to the terminal device time zone, terminal device 100 is currently within the peak hour, the policies can be: · Priority 1 : Wi-Fi access networks; and

Priority 2: 3GPP access networks.

This illustrated in Fig. 7 by the arrow labelled "200, OK - ISMP policies, Discover/Information". Step 5 of Fig. 7 corresponds to step s80 of Figs. 2a and 2b.

As a result, terminal device 100 prioritizes an attempt to attach to Wi- Fi access networks (priority 1) and, then, only in case of failure, terminal device 100 attempts to attach to a 3GPP access network (priority 2).

(step 6) ANDSF node's internal trigger wakes up at end of busy/peak hour according to the time zone of the area in which terminal device 100 is located (i.e., in the example, at 12:30 local time of terminal device 100, and at 11 :30 local time of ANDSF node 200), as illustrated in Fig. 7 by the small "X" sign. (step 7) ANDSF node 200 sends an SMS to terminal device 100 (as illustrated in Fig. 7 by the arrow labelled "WAP PUSH SMS") to instruct terminal device 100 to establish a new OMA DM session to renew access network policies in terminal device 100. (step 8) As a result of the communication received from ANDSF node 200 in step 7, terminal device 100 establishes an OMA DM session towards ANDSF node 200 requesting access network policies, as illustrated in Fig. 7 by the arrow labelled "HTTP POST - Policy request, UE_Location, Devjnfo, TimeZonelnfo". Namely, terminal device 100 provides the UE_Location, device information and policy request indication to ANDSF node 200. Terminal device 100 may, as in step 1 , provide information about its current time zone ("TimeZone"), which may have changed in the meantime. Assuming that the terminal device time zone has not changed, terminal device 100 is now outside the peak hour (i.e., terminal device local time is beyond 12:30h).

(step 9) ANDSF node 200 may, as in step 2, determine access network

policies that are applicable to terminal device 100 according to the terminal device's current (or latest) local time zone reported by terminal device 100. This is illustrated by the box labelled "ANDSF derives policies based on subscription type, UE_Location, and

TimeZone".

(step 10) ANDSF node 200 provides the access network policies previously determined in step 9 to terminal device 100, as illustrated by the arrow labelled "200, OK - ISMP policies, Discover/Information". These policies may be now, in this example:

Priority 1 : 3GPP access networks; and Priority 2: Wi-Fi access networks.

As a result, terminal device 100 uses the newly received access network policies to switch its current access network (if terminal device 100 proceeds according to the received policy).

Thus, some embodiments of the invention enable time-based access steering decisions centralized in the ANDSF node. Centralized time-based decisions in the ANDSF node are advantageous when the access selection criteria are time- dependent (for example, dependent on peak-hour conditions) and depend on other dynamic conditions the ANDSF node may be aware of, such as radio resource congestion in for example 3GPP access networks.

Fig. 8 is a schematic diagram of an exemplary implementation of a terminal device 100 that may use in embodiments of the invention. As illustrated, terminal device 100 may include a bus 105, a processing unit 103, a main memory 107, a ROM 108, a storage device 109, an input device 102, an output device 104, and a communication interface 106. Bus 105 may include a path that permits

communication among the components of terminal device 100.

Processing unit 103 may include a processor, a microprocessor, or processing logic that may interpret and execute instructions. Main memory 07 may include a RAM or another type of dynamic storage device that may store information and

instructions for execution by processing unit 103. ROM 108 may include a ROM device or another type of static storage device that may store static information and instructions for use by processing unit 103. Storage device 109 may include a magnetic and/or optical recording medium and its corresponding drive.

Input device 102 may include a mechanism that permits an operator to input information to terminal device 100, such as a keypad, a keyboard, a mouse, a pen, voice recognition and/or biometric mechanisms, etc. Output device 104 may include a mechanism that outputs information to the operator, including a display, a printer, a speaker, etc. Communication interface 106 may include any transceiver-like mechanism that enables terminal device 100 to communicate with other devices and/or systems (such as with a base station, a WLAN access point, an ANDSF node 200, etc.). For example, communication interface 106 may include

mechanisms for communicating with another device or system via a network.

Terminal device 100 may perform certain operations or processes described herein. These operations may be performed in response to processing unit 103 executing software instructions contained in a computer-readable medium, such as main memory 107, ROM 108, and/or storage device 109. A computer-readable medium may be defined as a physical or a logical memory device. For example, a logical memory device may include memory space within a single physical memory device or distributed across multiple physical memory devices. Each of main memory 107, ROM 108 and storage device 109 may include computer-readable media. The magnetic and/or optical recording media (e.g., readable CDs or DVDs) of storage device 109 may also include computer-readable media. The software instructions may be read into main memory 107 from another computer-readable medium, such as storage device 109, or from another device via communication interface 106.

The software instructions contained in main memory 109 may cause processing unit 103 to perform operations or processes described herein, such as sending time zone information or local clock time information to an ANDSF node. Alternatively, hardwired circuitry may be used in place of or in combination with software instructions to implement processes and/or operations described herein. Thus, implementations described herein are not limited to any specific combination of hardware and software.

Fig. 9a schematically illustrates, as one embodiment of the invention (according to solution A), a terminal device 100. The terminal device 100 illustrated on Fig. 9a may for example be implemented as illustrated on Fig. 8.

Terminal device 100 comprises a unit, referred to as "time zone information sending unit" 120ai, configured for sending, to a network node 200 hosting an ANDSF, said network node being hereinafter referred to as "ANDSF node", information 50a

("time zone information") about the time zone associated with the geographical area in which the terminal device 100 is located.

Fig. 9b schematically illustrates, as one embodiment of the invention (according to solution B), a terminal device 100. The terminal device 100 illustrated on Fig. 9b may for example be implemented as illustrated on Fig. 8 as well.

Terminal device 100 comprises a unit, referred to as "local clock time sending unit" 120bi, configured for sending, to a network node 200 hosting an ANDSF, said network node being hereinafter referred to as "ANDSF node", information 50b

("local clock time information") about the local clock time of the terminal device 100.

In embodiments of the invention, terminal device 100 described with reference to Fig. 9a or 9b further comprise another unit, hereinafter referred to as "access network policy receiving unit" 180₂, configured for receiving, from ANDSF node 200, information for subsequently enabling terminal device 100 to implement (i.e. to enforce) the at least one access network policy received from the ANDSF node 200. Such embodiments are illustrated by Figs. 10a and 10b. Fig. 11a schematically illustrates, as one embodiment of the invention (according to solution A), a network node 200 hosting an ANDSF entity, i.e. an ANDSF node 200.

ANDSF node 200 comprises two units, a so-called time zone information receiving unit 220a₂ and a so-called access network policy determining unit 260. Time zone information receiving unit 220a₂ is configured for receiving, from a terminal device 100, information 50a ("time zone information") about the time zone associated with the geographical area in which the terminal device 100 is located. Access network policy determining unit 260 is configured for determining at least one access network policy, based on the time zone information 50a.

Fig. 11b schematically illustrates, as one embodiment of the invention (according to solution B), a network node 200 hosting an ANDSF entity, i.e. an ANDSF node 200.

ANDSF node 200 comprises three units, a so-called a local clock time information receiving unit 220b₂, a so-called time zone information determining unit 240, and a so-called access network policy determining unit 260.

Local clock time information receiving unit 220b₂ is configured for receiving, from a terminal device 100, information 50b ("local clock time information") about the local clock time of the terminal device 100. Time zone information determining unit 240 is configured for determining information ("time zone information") about the time zone associated with the geographical area in which the terminal device 100 is located, based on the difference between the local clock time information 50b received from the terminal device 100 and local clock time information of ANDSF node 200.

Access network policy determining unit 260 is configured for determining, based on the time zone information, at least one access network policy.

In embodiments of the invention, ANDSF node 200 described with reference to Fig. 11a or 11b further comprise another unit, referred to as "access network policy sending unit" 280i, which is configured for sending, to terminal device 100, information for enabling terminal device 100 to subsequently implement (i.e. to enforce) the at least one access network policy received from the ANDSF node 200. Such embodiments are illustrated by Figs. 12a and 12b. The network node (i.e., ANDSF node 200) illustrated with reference to any of the Figs. 11a to 12b may for example be implemented as illustrated on Fig. 8 as well. Namely, the ANDSF node 200 can comprise: a bus 105, a processing unit 103, a main memory 107, a ROM 108, a storage device 109, an input device 102, an output device 104, and a communication interface 106. In particular, the software instructions contained in a memory of the ANDSF node 200 may cause the processing unit 103 of the ANDSF node 200 to perform operations or processes described herein, such as determining one or more access network policies based on the time zone information received from a terminal device, and/or based on the local time information received from a terminal device.

In one embodiment, any one of the above-access network policy determining unit 260 is further configured for selecting a type of access network to which the terminal device 00 should attach. For example, the selected type of access network may be a 3GPP access network (for example a GERAN, a UTRAN, or a E- UTRAN) or a non-3GPP access network (for example a wireless LAN interoperable with IEEE 802.11 standards, or a wireless MAN interoperable with IEEE 802.16 standards). In one embodiment, access network policy determining unit 260 is configured for selecting one single access network to which the terminal device 100 should attach.

In one embodiment, access network policy determining unit 260 is configured for selecting a plurality of access networks, wherein the terminal device 100 should attach to one amongst the plurality of access networks.

In one embodiment, access network policy determining unit 260 is further configured for determining the at least one access network policy based on at least one of: (i) the time of the day; and (ii) congestion information associated with the access networks available in the area in which terminal device 100 is located.

In one embodiment, access network policy determining unit 260 is further configured for accessing a database storing at least: (a) information identifying time zones; and (b) for each time zone, local time values identifying the time zone's peak hour time; and access network policies for the time zone's peak hour time.

Where the terms "time zone information sending unit", "local clock time information sending unit", "access network policy receiving unit", "time zone information receiving unit", "local clock time information receiving unit", "access network policy determining unit", "time zone information determining unit", "access network policy sending unit", etc. are used herewith, no restriction is made regarding how distributed these elements may be and regarding how gathered elements may be. That is, the constituent elements of a unit, function or network node may be distributed in different software or hardware components or devices for bringing about the intended function. A plurality of distinct elements may also be gathered for providing the intended functionalities.

Any one of the above-referred units of a network node may be implemented in hardware, software, field-programmable gate array (FPGA), application-specific integrated circuit (ASICs), firmware or the like.

In further embodiments of the invention, any one of the above-mentioned time zone information sending unit, local clock time information sending unit, access network policy receiving unit, time zone information receiving unit, local clock time information receiving unit, access network policy determining unit, time zone information determining unit, access network policy sending unit, etc. is replaced by time zone information sending means, local clock time information sending means, access network policy receiving means, time zone information receiving means, local clock time information receiving means, access network policy determining means, time zone information determining means, access network policy sending means, etc. respectively, for performing the functions of the time zone information sending unit, local clock time information sending unit, access network policy receiving unit, time zone information receiving unit, local clock time information receiving unit, access network policy determining unit, time zone information determining unit, access network policy sending unit, etc.

In further embodiments of the invention, any one of the above-described

procedures, steps or processes may be implemented using computer-executable instructions, for example in the form of computer-executable procedures, methods or the like, in any kind of computer languages, and/or in the form of embedded software on firmware, integrated circuits or the like.

Although the present invention has been described on the basis of detailed examples, the detailed examples only serve to provide the skilled person with a better understanding, and are not intended to limit the scope of the invention. The scope of the invention is much rather defined by the appended claims.

Abbreviations: 3GPP 3rd Generation Partnership Project

AAA Authentication, authorization and accounting

ANDSF Access Network Discovery and Selection Function DM Device management

E-UTRAN Evolved UMTS Terrestrial Radio Access

EDGE Enhanced Data rates for GSM Evolution

EPC Evolved Packet Core

ePDG Evolved Packet Data Gateway

EPS Evolved Packet System

GERAN GSM EDGE radio access network

GSM Global System for Mobile Communications

HPLMN Home public land mobile network

HSS Home Subscriber Server

IFOM IP Flow Mobility

IMS IP Multimedia Subsystem

IP Internet Protocol

IP-CAN IP Connectivity Access Network

ISMP Inter-system mobility policy

ISRP Inter-system routing policy

LAN Local area network

M2M Machine-to-machine

MAN Metropolitan area network

MAPCON Multi Access PDN Connectivity

MO Management object

OMA Open Mobile Alliance

PCC Policy control and charging

PCEF Policy and charging enforcement function

PCRF Policy and charging rules function

PDP Packet Data Protocol

PEP Policy enforcement point

PLMN Public land mobile network

PSS Packet Switch Streaming

QoS Quality of Service

RAT Radio Access Type

SAE System Architecture Evolution

SIM Subscriber identity module

UDR User data repository

UE User equipment

UMTS Universal Mobile Telecommunications System

UTRAN Universal Terrestrial Radio Access Network

WLAN Wireless LAN

WMAN Wireless MAN

WAP Wireless Application Protocol

WiMAX Worldwide Interoperability for Microwave Access

Claims

Method carried out in a telecommunication network, the method comprising sending (s20a), by a terminal device (100), to a network node (200) hosting an access network discovery and selection function, said network node being hereinafter referred to as "ANDSF node", information (50a) about the time zone associated with the geographical area in which the terminal device (100) is located, said information being hereinafter referred to as "time zone information"; and

determining (s60), by the ANDSF node (200), at least one access network policy, based on the time zone information (50a).

Method carried out in a telecommunication network, the method comprising sending (s20b), by a terminal device (100), to a network node (200) hosting an access network discovery and selection function, said network node being hereinafter referred to as "ANDSF node", information (50b) about the local clock time of the terminal device (100), said information being hereinafter referred to as "local clock time information";

determining (s40b), by the ANDSF node (200), information about the time zone associated with the geographical area in which the terminal device (100) is located, said information being hereinafter referred to as "time zone information", based on the difference between the local clock time

information (50b) received from the terminal device (100) and local clock time information of the ANDSF node (200); and

determining (s60), by the ANDSF node (200), at least one access network policy, based on the time zone information.

Method of claim 1 or 2, wherein the step of determining (s60) at least one access network policy comprises

selecting a type of access network to which the terminal device (100) should attach.

Method of claim 3, wherein the selected type of access network comprises any one of

a 3GPP access network; and

a non-3GPP access network.

5. Method of claim 4, wherein the 3GPP access network is any one of a GERAN;

a UTRAN; and

a E-UTRAN.

6. Method of claim 4 or 5, wherein the non-3GPP access network is any one of a wireless LAN interoperable with IEEE 802.11 standards; and a wireless MAN interoperable with IEEE 802.16 standards.

selecting one access network to which the terminal device ( 00) should attach.

selecting a plurality of access networks, wherein the terminal device (100) should attach to one of the plurality of access networks.

Method according to any one of the preceding claims, the method further comprising

sending (s80), by the ANDSF node (200) to the terminal device (100), information for enabling the terminal device (100) to implement the at least one access network policy.

Method according to any one of the preceding claims, wherein determining (s60) the at least one access network policy is further based on at least one of:

the time of the day; and

congestion information associated with the access networks available in the geographical area in which the terminal device (100) is located.

Method according to any one of the preceding claims, wherein determining (s60) the at least one access network policy comprises accessing a database storing at least:

information identifying time zones; and

for each time zone,

local time values identifying the time zone's peak hour time; and access network policies for the time zone's peak hour time.

12. Method carried out by a terminal device (100), the method comprising

sending (s20ai), to a network node (200) hosting an access network discovery and selection function, said network node being hereinafter referred to as "ANDSF node", information (50a) about the time zone associated with the geographical area in which the terminal device (100) is located, said information being hereinafter referred to as "time zone information".

13. Method carried out by a terminal device (100), the method comprising

sending (s20bi), to a network node (200) hosting an access network discovery and selection function, said network node being hereinafter referred to as "ANDSF node", information (50b) about the local clock time of the terminal device (100), said information being hereinafter referred to as "local clock time information".

14. Method of claim 12 or 13, the method further comprising

receiving (s80₂), from the ANDSF node (200), information for enabling the terminal device (100) to implement the at least one access network policy.

15. Method carried out by a network node (200) hosting an access network

discovery and selection function, said network node being hereinafter referred to as "ANDSF node", the method comprising

receiving (s20a₂), from a terminal device (100), information (50a) about the time zone associated with the geographical area in which the terminal device (100) is located, said information being hereinafter referred to as "time zone information"; and

determining (s60) at least one access network policy, based on the time zone information (50a).

16. Method carried out by a network node (200) hosting an access network

receiving (s20b₂), from a terminal device (100), information (50b) about the local clock time of the terminal device (100), said information being hereinafter referred to as "local clock time information"; determining (s40b) information about the time zone associated with the geographical area in which the terminal device (100) is located, said information being hereinafter referred to as "time zone information", based on the difference between the local clock time information (50b) received from the terminal device (100) and local clock time information of the ANDSF node (200); and

determining (s60) at least one access network policy, based on the time zone information. 17. Method of claim 15 or 16, wherein the step of determining (s60) at least one access network policy comprises

selecting a type of access network to which the terminal device (100) should attach. 18. Method of claim 17, wherein the selected type of access network comprises any one of

a 3GPP access network; and

a non-3GPP access network. 19. Method of claim 18, wherein the 3GPP access network is any one of

a GERAN;

a UTRAN; and

a E-UTRAN. 20. Method of claim 18 or 19, wherein the non-3GPP access network is any one of

a wireless LAN interoperable with IEEE 802.11 standards; and a wireless MAN interoperable with IEEE 802.16 standards. 21. Method of claim 15 or 16, wherein the step of determining (s60) at least one access network policy comprises

selecting one access network to which the terminal device (100) should attach. 22. Method of claim 15 or 16, wherein the step of determining (s60) at least one access network policy comprises

23. Method according to any one of claims 15 to 22, the method further comprising

sending (s80i), to the terminal device (100), information for enabling the terminal device (100) to implement the at least one access network policy.

Method according to any one of claims 15 to 23, wherein determining (s60) the at least one access network policy is further based on at least one of: the time of the day; and

Method according to any one of claims 15 to 24, wherein determining (s60) the at least one access network policy comprises accessing a database storing at least:

information identifying time zones; and

for each time zone,

local time values identifying the time zone's peak hour time; and

access network policies for the time zone's peak hour time.

26. Terminal device (100) comprising

a unit (120a-i), hereinafter referred to as "time zone information sending unit", configured for sending, to a network node (200) hosting an access network discovery and selection function, said network node being hereinafter referred to as "ANDSF node", information (50a) about the time zone associated with the geographical area in which the terminal device (100) is located, said information being hereinafter referred to as "time zone information".

Terminal device (100) comprising

a unit (120bi), hereinafter referred to as "local clock time sending unit", configured for sending, to a network node (200) hosting an access network discovery and selection function, said network node being hereinafter referred to as "ANDSF node", information (50b) about the local clock time of the terminal device (100), said information being hereinafter referred to as "local clock time information".

28. Terminal device (100) of claim 26 or 27, further comprising

another unit (180₂), hereinafter referred to as "access network policy receiving unit", configured for receiving, from the ANDSF node (200), information for enabling the terminal device (100) to implement the at least one access network policy.

29. Network node (200) hosting an access network discovery and selection function, said network node being hereinafter referred to as "ANDSF node", the ANDSF node (200) comprising

a first unit (220a₂), hereinafter referred to as "time zone information receiving unit", configured for receiving, from a terminal device (100), information (50a) about the time zone associated with the geographical area in which the terminal device (100) is located, said information being hereinafter referred to as "time zone information"; and

a second unit (260), hereinafter referred to as "access network policy determining unit", configured for determining at least one access network policy, based on the time zone information (50a).

30. Network node (200) hosting an access network discovery and selection function, said network node being hereinafter referred to as "ANDSF node", the ANDSF node (200) comprising

a first unit (220b₂), hereinafter referred to as "local clock time information receiving unit", configured for receiving, from a terminal device (100), information (50b) about the local clock time of the terminal device (100), said information being hereinafter referred to as "local clock time information";

a second unit (240), hereinafter referred to as "time zone information determining unit", configured for determining information about the time zone associated with the geographical area in which the terminal device (100) is located, said information being hereinafter referred to as "time zone information", based on the difference between the local clock time

a third unit (260), hereinafter referred to as "access network policy determining unit", configured for determining at least one access network policy, based on the time zone information.

31. ANDSF node (200) of claim 29 or 30, wherein the access network policy determining unit (260) is further configured for selecting a type of access network to which the terminal device (100) should attach.

ANDSF node (200) of claim 31 , wherein the selected type of access network comprises any one of

a 3GPP access network; and

a non-3GPP access network.

ANDSF node (200) of claim 32, wherein the 3GPP access network is any one of

a GERAN;

a UTRAN; and

a E-UTRAN.

ANDSF node (200) of claim 32 or 33, wherein the non-3GPP access network is any one of

a wireless LAN interoperable with IEEE 802.11 standards; and a wireless MAN interoperable with IEEE 802.16 standards.

ANDSF node (200) of claim 29 or 30, wherein the access network policy determining unit (260) is further configured for

selecting one access network to which the terminal device (100) should attach.

ANDSF node (200) according to any one of claims 29 to 36, the ANDSF node (200) further comprising

another unit (280i), hereinafter referred to as "access network policy sending unit", configured for sending, to the terminal device (100), information for enabling the terminal device (100) to implement the at least one access network policy.

38. ANDSF node (200) according to any one of claims 29 to 37, wherein the access network policy determining unit (260) is further configured for determining the at least one access network policy based on at least one of: the time of the day; and

congestion information associated with the access networks available in the geographical area in which the terminal device (100) is located. 39. ANDSF node (200) according to any one of claims 29 to 37, wherein the access network policy determining unit (260) is further configured for accessing a database storing at least:

information identifying time zones; and

for each time zone,

local time values identifying the time zone's peak hour time; and

access network policies for the time zone's peak hour time. 40. Computer program comprising computer executable instructions configured, when carried out on a computer, to cause the computer to execute a method according to any one of claims 12 to 25.

41. Computer program product comprising a computer program according to claim 40.