FLOW CONTROL IN COMMUNICATIONS SYSTEM

FIELD

The invention relates to arranging flow control in a communications system. BACKGROUND

Packet-switched data transmission services have been developed for mobile terminals. GPRS (General Packet Radio Service) is a service widely used in terminals supporting the GSM radio technology. Packet-switched services of the 3GPP (Third-Generation Partnership Project) system applying the WCDMA (Wideband Code Division Multiple Access) radio technology are also based on GPRS.

Besides access via conventional PLMN (Public Land Mobile Network) access networks, such as a BSS (Base Station Sub-system) of the GSM, there is also a need to enable access to services of a PLMN by local networks primarily targeted at providing high speed data transmission in a limited area, such as in an office building. WLAN (Wireless Local Area Network) technologies are very popular today and standardization work has been done in the 3GPP to define WLAN-3GPP interworking. This interworking may include the usage of 3GPP subscriber management procedures, such as au- thentication and charging procedures, as well as data transmission via the 3GPP core network for mobile terminals accessing a WLAN network.

3GPP specification TS 43.318 "Generic access to the A/Gb interface; Stage 2", version 6.7.0, June 2006, describes an overall architecture for Generic Access (GA) to the A/Gb interfaces, i.e. interfaces from access net- work to a mobile switching center MSC and a serving GPRS support node SGSN, respectively. Generic Access to the A/Gb interfaces, or GA, is an extension of GSM/GPRS mobile services that is achieved by tunneling 3GPP non-access stratum NAS protocols between a mobile station MS and the 3GPP core network over an IP network. The IP access network may be a WLAN but could be some other radio access network as well. The GA is a complement to traditional GSM/GPRS/UTRAN radio coverage. A generic access network controller (GANC) is an element between the generic IP access network and the A/Gb interface to the 3GPP core network. The GANC appears to the core network as a GSM/EDGE radio access network GERAN or a base station subsystem BSS.

3GPP specification TS 44.318 "Generic Access (GA) to the A/Gb interface; Mobile GA interface layer 3 specification", version 7.0.0, July 2006, describes procedures used over a generic access interface between the GANC and the mobile station MS connected to the IP access network, i.e. the Up interface. This document specifies the handling of a secure connection, discovery and registration, circuit-switched CS domain and packet-switched PS domain signaling, voice and data. In order to be able to access PLMN CS domain services via GAN and the GANC, the MS has to register in the GANC, and after registration, request establishment of a connection between the MS and the GANC.

For PS domain, after a transport channel has been established, the mobile station in the GAN system implements a flow control algorithm to monitor and calculate the data rate that could be supported based on the current conditions. When a flow control condition is detected, the mobile station re- calculates an estimated data rate that could be supported and sends a flow control request to the GANC to adjust the data rate accordingly. However, there is further need to improve the flow control.

SUMMARY

Methods, apparatuses, computer readable mediums, and a module are now provided, which are characterized by what is stated in the independent claims. Some embodiments are disclosed in the dependent claims.

According to an aspect, a registration message comprising information about one or more supported data rates of the communications device is generated after detecting a need for registration or registration update for a communications device. The registration message is transmitted for registering the communications device or for updating registration of the communications device in the communications network. The term "registering" is to be construed broadly to refer to any actions for making the communications device known in the communications network. For instance, if, as a result of the regis- tration procedure, the communications device has been accepted to attach the network, the communications device may request data transmission context.

According to an embodiment, information on at least one preferred or default data rate is stored in the communications device. The information about one or more supported data rates in the registration message is speci- fied on the basis of the stored information on at least one preferred or default data rate.

According to another aspect, a registration message for registering a communications device or for updating a registration of the communications device is received in a communications network, the registration message comprising information about one or more supported data rates of the commu- nications device. The communications device is registered, or the registration of the communications device is updated in the communications network on the basis of the received registration message. Data flow control for the communications device is adapted in accordance with the information in the received registration message. According to an embodiment, the registration message is for registering the communications device via a radio access network in a network element providing access to a public land mobile network PLMN core network to provide packet-switched core network communications services for the communications device via the radio access network. According to still another aspect, a message comprising information about one or more supported data rates of the communications device is generated for a device requiring PLMN services via a non-PLMN radio access network. The message is transmitted for a network element providing access to a public land mobile network PLMN core network. Transfer of PLMN core network communications is arranged for the communications device via the non-PLMN radio access network in accordance with the data rate information.

According to an embodiment, the message is a request message for activating a transport channel between the network element and the communications device to carry upper layer communications between the communica- tions device and the PLMN core network.

According to an embodiment, the data rate information specifies a maximum downlink data rate value, and the network element is configured to control the downlink data flow not to exceed the maximum downlink data rate value. According to an aspect, there is now provided a communications apparatus comprising a control unit and memory for storing program code at least partially controlling operations in the communications apparatus, wherein the communications apparatus is configured to determine a need for a wireless connection, the communications apparatus is configured to generate a mes- sage for connection establishment, the message comprising information about one or more supported data rates of the communications apparatus, and the

Communications apparatus is configured to transmit the message for a network element providing access to a public land mobile network PLMN core network, to arrange transfer of PLMN core network communications for the communications apparatus via the non-PLMN radio access network in accordance with the data rate information.

According to an embodiment, the message is a request message for activating a transport channel between the network element and the communications apparatus to carry upper layer communications between the communications apparatus and the PLMN core network. According to an embodiment, the communications apparatus is configured to specify a maximum downlink data rate value in the message for the network element to control the downlink data flow not to exceed the maximum downlink data rate value.

According to an aspect, there is now provided a communications apparatus comprising a control unit and memory for storing program code at least partially controlling operations in the communications apparatus, wherein the communications apparatus is configured to function as a network element providing access to a public land mobile network PLMN core network for a communications terminal connected to a non-PLMN radio access network, the communications apparatus is configured to receive a message for connection establishment from the communications terminal, the message comprising information about one or more supported data rates of the communications terminal, and the communications apparatus is configured to arrange transfer of PLMN core network communications for the communications terminal via the non-PLMN radio access network in accordance with the data rate information.

According to an embodiment, the message is a request message for activating a transport channel between the communications apparatus and the communications terminal to carry upper layer communications between the communications terminal and the PLMN core network, and the communica- tions apparatus is configured to control data flow of a transport channel activated for the communications terminal in accordance with the data rate information.

According to an embodiment, the communications apparatus is configured to detect information on a maximum downlink data rate value for the communications terminal in the message, and the communications apparatus is configured to control the downlink data flow for the communications terminal

such that the downlink data rate would be at the most at the level of the maximum downlink data rate value.

According to an embodiment, the communications apparatus is a generic access network controller arranged to control packet-switched domain user plane data transfer over a generic access packet-switched resources transport channel between the generic access network controller and the communications terminal, the channel activation being arranged based on the message received from the communications terminal.

The aspects of the invention provide various advantages. One ad- vantage of an aspect is that interoperation between the communications device and the network is enhanced. Further features and advantages will become apparent from the following description and accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

In the following, some embodiments will be described in detail with reference to the accompanying drawings, in which

Figure 1 generally illustrates a 3GPP system with generic IP access network;

Figure 2a shows protocol architecture for packet-switched (PS) control plane in a 3GPP system with generic IP access network; Figure 2b shows protocol architecture for PS user plane in a 3GPP system with generic IP access network;

Figures 3a, 3b, and 3c are flow diagrams illustrating of some embodiments of the present invention;

Figure 4a, 4b, and 4c illustrate further embodiments of the present invention;

Figures 5a and 5b illustrate information elements according to some embodiments of the present invention;

Figure 6a illustrates basic elements of a mobile communications apparatus; and Figure 6b illustrates basic elements of a network element apparatus.

DETAILED DESCRIPTION OF EMBODIMENTS

An embodiment is illustrated next with reference to a 3GPP GAN in- terworking system illustrated in Figure 1. However, various embodiments of the present invention are applicable to any system in which a communications de- vice registers to a network controlling a data flow associated with the commu-

nications device. The present general method and the apparatus and means to implement the method can be used in connection with any 2G, 3G, 4G or higher generation mobile communication technology and their different versions. In one embodiment the local access network is any IEEE 802-based wireless local area network. For instance, the local access network may be an IEEE 802.1 1 or 802.16 (or Wimax) based network. However, present embodiments may be applied in other types of radio access networks via which an access to PLMN core network services may be arranged, such as networks operating at unlicensed frequency bands, for instance a network according to the BRAN (Broadband Radio Access Networks) standard, a Home RF network or a Bluetooth network.

Reference is now made to Figure 1 , in which the main parts of a mobile system include a generic IP access network GAN 20 and a 3GPP core network part 48 for PLMN circuit-switched CS and packet-switched PS domain services, and a mobile station MS 10, also called user equipment UE in many 3GPP specifications.

As illustrated in Figure 1 , 3GPP core network services may also be accessed via other radio access networks, such as a UMTS terrestrial radio access network UTRAN 50, a GSM base station subsystem BSS/GSM/EDGE radio access network GERAN 60, or an EUTRAN (3GPP proposal of an evolution of the 3G WCDMA system towards a beyond 3G system). The GSM radio access network 60 includes base transceiver stations (BTS) and base station controllers (BSC). The UTRAN 50 includes base stations BS, which are called Node Bs, and radio network controllers (RNC). The mobile station MS 10 may be a mobile phone, a table computer with a WLAN radio interface adapter, or a PDA type of device, for instance. There may be mobile stations MS of different classes according to their capabilities. The MS 10 may support data transfer via the GAN 20, UTRAN 50, BSS/GERAN 60, and/or some other network, even substantially simultane- ously. The MS 10 is equipped with an IC card including a (universal) subscriber identity module utilized by a 3GPP subscriber to access the GAN for 3GPP interworking purposes.

The GAN 20 may be any type of local Internet protocol IP based access network. The GAN 20 may be a local non-PLMN, or non-cellular type of network, such as a wireless local area network. The GAN 20 can operate as a 3GPP access network, and it may be further configured to provide access to

other networks, such as the Internet. The GAN comprises access elements, typically called access points AP, which provide a mobile station MS 10 with radio access and thus terminate the radio connection. The GAN 20 may also comprise further network elements, such as a control element and/or a gate- way element.

The 3GPP core network 48 comprises an MSC 40 for CS domain services, an SGSN 42 and a gateway GPRS support node GGSN (not shown) for PS domain services. Furthermore, the system comprises an Authentication, Authorization and Accounting (AAA) server 44, which is used to authenticate a mobile station MS 10 accessing the GAN 20. 3GPP network subscriber data and authentication services can thus be used for mobile stations MS roaming in the GAN and comprising a UMTS subscriber identity module USIM and/or a (GSM) SIM. An HLR/HSS 46 (Home Location Register/ Home Subscriber Server) located within the 3GPP subscriber's home network is the entity con- taining the authentication and subscription data required for the 3GPP subscriber to access 3GPP services. It is to be noted that the 3GPP system comprises many further elements/functions not illustrated in Figure 1 for clarity purposes.

A generic access network controller GANC 30 is a network element between the generic IP access network and the A/Gb interface to the 3GPP core network. It includes a security gateway SEGW 32 that terminates secure remote access tunnels from the MS 10, providing mutual authentication, encryption and data integrity for signalling, voice and data traffic. The SEGW 32 supports Wm authentication procedures with the AAA proxy/server 44. The IP transport connection extends from the GANC 30 to the MS 10. A single interface, the Up interface, is defined between the GANC and the MS. As regards packet-switched services, the GANC 30 provides inter-working data transport channels over the Up interface to packet flows over the Gb interface. Hence, the GANC 30 is a network element providing transfer of PLMN core network communications for the MS 10 device via the non-PLMN radio access network 20.

Figure 2a illustrates protocol architecture for PS control plane in a 3GPP system with a generic IP access network (such as the GAN 20). Access layers and transport IP layer provide the generic connectivity between the MS 10 and the GANC 30. The IPsec layer provides encryption and data integrity. The Remote IP layer is the 'inner' IP layer for IPsec tunnel mode and is used

by the MS to be addressed by the GANC. Remote IP layer is configured during the IPsec connection establishment. TCP is used to provide reliable transport for GA-RC (Generic Access - Resource Control) between the MS and the GANC and is transported using the Remote IP layer. The GA-RC manages the IP connection, including the GAN registration procedures.

The GA-PSR (Generic Access - Packet Switched Resources) protocol performs functionality equivalent to the GPRS-RLC (Radio Link control) protocol. The concept of a TBF (Temporary Block Flow) is replaced by mechanisms to manage an IP connection between the MS and the GANC. Upper pro- tocols, such as the LLC and above, are carried transparently between the MS and the core network 48. The GANC terminates the GA-PSR protocol and inter-works it to the Gb interface using BSSGP (Base Station System GPRS Protocol).

Figure 2b shows protocol architecture for packet-switched (PS) user plane in a 3GPP system with generic IP access network. The GA-PSR operates between the MS 10 to the GANC 30 transporting the user plane data across the Up interface. Upper protocols and data, such as the LLC and above, are carried transparently between the MS 10 and the CN 48 over user datagram protocol UDP. A GA-PSR Transport Channel (GA-PSR TC) provides the association between the MS and GANC for the transport of GPRS user data over the Up interface. Given that the GAN user data transport is UDP based, the GA- PSR Transport Channel is associated with corresponding MS and GANC IP addresses and UDP ports used for GPRS user data transfer. The MS and GANC manage the GA-PSR Transport Channel based on the requests for data transfer and a configurable GA-PSR channel timer.

For a more detailed description of the generic access to the A/Gb interface, reference is made to the 3GPP specification TS 43.318 "Generic access to the A/Gb interface; Stage 2", version 6.7.0, June 2006, incorporated herein by reference. It is to be noted that the GAN-3GPP interworking specification work is not finished at the time of filing of the present application, and the basic principles of the solution being described can be applied in modified GAN-3GPP interworking systems.

To obtain services via the GAN 20, the mobile station 10 has to per- form a GAN technology-specific access procedure, for instance by applying some IEEE 802.1 x based access procedure. In order to be able to access

PLMN services via the GAN 20 and the GANC 30, the MS 10 has to select a GANC 30 and register to the selected GANC. The MS 10 defines a network element or controller providing access to the core network services, in the present embodiment a GANC to which the MS 10 shall attach. This may involve at least some of the discovery procedures illustrated in Chapter 5 of the 3GPP specification TS 44.318 "Generic Access (GA) to the A/Gb interface; Mobile GA interface layer 3 specification", version 7.0.0, July 2006, incorporated herein by reference. After Discovery, the MS 10 starts a registration procedure to register the MS for GAN services on the GANC 30. It is to be noted that if the MS 10 is initially aware of a default GANC, which is also available, the MS does not have to perform the Discovery procedure, but may simply select the predetermined default GANC as the target for registration.

Figures 3a and 3b illustrate features related to registering a (terminal) communications apparatus according to an embodiment. These features, and their further embodiments, may be applied in connection with the 3GPP GAN registration, but are not limited thereto. Figure 3a illustrates steps that may be carried out in a communications apparatus, such as the MS 10. In step 300 there is a need to register the apparatus to a selected network element in the communications network, or to update an already existing registration. Data rate information illustrative of the apparatus capabilities and to be transmitted by a registration message to the network is defined in step 302. The definition may involve retrieval of a pre-determined value from the memory of the apparatus or calculation of an appropriate data rate on the basis of current operating conditions, for instance. The apparatus may hold information of supported data rates, whereby the information may be based on apparatus implementation capability or current operating conditions, for instance. A default value may be set to the memory of the apparatus, e.g. as specified in the protocol software, and the default value is automatically used. However, the apparatus may be configured to adapt the value or select the value on the basis of predetermined rules. It is to be noted that the data rate information may be a specific data rate value, a plurality of values, or indicate a range of values.

In step 304 a registration message is generated, wherein the message comprises an information element indicating one or more supported data rates. In step 306 the registration message is transmitted to a selected network element, such as a selected GANC 30.

Figure 3b illustrates features of an entity receiving a registration request, such as the GANC 30. In step 350 a registration message is received from a communications apparatus. The message is checked 352 for data rate information. A registration procedure, which may be an initial procedure or an update, may be performed for the apparatus, whereby the apparatus may be registered as appropriate in the applied system. The data rate information is stored 354 as associated with the apparatus. This step may be entered if the initial registration or registration update for the apparatus is accepted. The data rate information may be associated with the MS 10, or in particular with the MS subscriber. The data rate information may be stored in the memory of a device implementing steps of Figure 3b or to another storage, in association with other registration related data.

When there is need for data transfer to and/or from the registered apparatus, the data rate information may be retrieved and the data rate of the data transfer is adapted 356 in accordance with the data rate information. The entity applying the method of Figure 3b may initiate a specific data flow control process on the basis of the received data rate information, or the received data rate information may serve as an additional control parameter for flow control process. In one embodiment the stored data rate information is retrieved and the data flow control is initiated in step 356 upon a request for a communications context, such as a request for a transport channel to/via a radio access network. In another embodiment the data flow control is initiated as a response to a need to transfer packet(s) to/from the registered communications appara- tus. In both of these embodiments, already the beginning of the data transfer may be adapted according to the properties of the communications apparatus. In an embodiment applied to the GA system, step 356 may be entered in response to MS or network initiated channel activation, such as the GA PSR TC activation procedures in Chapters 8.1 and 8.3 of the above-mentioned 3GPP specification TS 44-318, incorporated herein by reference.

Broken lines are used to illustrate that the data transfer may begin later after registration as a response to a further trigger, such as a transport channel activation request or downlink user data received in the GANC 30. It is to be noted that the basic procedure of Figure 3a and 3b may be applied in connection with initial registration or with registration update, which may occur during an ongoing user plane data transfer.

Since information on the supported data rates has been submitted during registration, the data rate information is thus readily available before the beginning of data transmission by the network. Hence, the network may initially start the data transmission at a rate suitable for the communications device (10), and errors related to the network initially starting data transferring on a data rate, which the communications apparatus cannot handle, can be avoided or at least reduced. Since a network apparatus (30) may be configured to start transmission at a rate suitable for the receiving communications device, problems related to different network configurations with different initial data trans- mission rates may be avoided. Further, by suitable definition of the data rate information it is possible to reduce flow control procedures initiated by the communications device during data transfer, thus reducing the signaling between the communications device and the network.

In the following some further embodiments are disclosed, in which downlink flow control is arranged in step 356 on the basis of the data rate information provided by the communications (terminal) apparatus. Although the embodiments are illustrated in connection with the MS 10 and the GANC 30, the illustrated features may be employed in other communications apparatuses. As already indicated, besides or instead of downlink data flow control, in one embodiment uplink data transfer flow control is arranged on the basis of the data rate information. Hence, the MS 10 may be configured to apply specifically pre-determined or dynamically specified uplink data rate information for uplink data flow control on MS or packet flow context PFC level.

In one embodiment the data rate information (as initially stored or as updated) is maintained until the communications apparatus, such as the MS 10, is deregistered. As illustrated in Figure 3c, in response to receiving a de- registration message from the apparatus or detecting a need for network- initiated deregistration 380, the stored data rate information is removed 382.

Figures 4a and 4b are signalling diagrams illustrating some em- bodiments in the GAN system. Figure 4a illustrates use of a registration request message for informing the GANC 30 of the data rate supported by the MS 10.

In general, for all communications over the Up interface, the MS 10 and the GANC 30 first establish a tunnel as a result of an authentication pro- cedure (not shown). The applicability of the present functions is not limited to any specific underlying transport technology. For instance, various tunneling

techniques may be applied in 3GPP-GAN based embodiments. In one embodiment, tunnels are IPSec tunnels and procedures illustrated in Chapter 4 of the above-identified 3GPP TS 44.318 may be applied, incorporated herein by reference. After reserving appropriate lower layer resources and a possible Discovery procedure, the MS initiates a registration procedure with the defined GANC 30. The MS 10 is arranged to define at least one data rate value and form a GA-RC REGISTER REQUEST message including information on supported data rates. The message is sent 402 to the GANC 30, which stores 404 the data rate information encoded in the received message. The GANC 30 transmits 406 a GA-RC REGISTER ACCEPT message to the MS. After registration, the MS 10 is able to receive services from the GANC 30 and the GA- RC sub-layer in the MS 10 is in GA-RC-REGISTERED state.

As regards PS user data transfer for the registered MS 10, the GA- PSR sub-layer in the MS 10 can be in two states: GA-PSR-IDLE or GA-PSR- DEDICATED. The MS 10 moves from the GA-PSR-IDLE state to the GA-PSR- DEDICATED state when the GA-PSR transport channel (TC) is activated. As a response to a need to enable LLC-PDU transfer for the MS 10 and via the GANC 30, the GA-PSR TC activation procedure is initiated. It is to be noted that there may be many triggers for this. For instance, a user input to select a packet data transfer context activation may have been detected just before step 304 or already earlier before step 300. In the mobile-initiated embodiment of Figure 4a, the MS transmits 408 a GA-PSR ACTIVATE-UTC-REQ message to the GANC 30.

If the GANC 30 accepts the GA-PSR connection establishment re- quest, it sends 410 a GA-PSR REQUEST ACCEPT message to the MS 10. The MS 10 may then move into the GA-PSR-DEDICATED state and upper layer data transfer may begin. While the corresponding GA-PSR TC is available, both the MS 10 and the GANC 30 can initiate GPRS user data transfer automatically using GA-PSR UNITDATA service. For uplink transfer, the GANC 30 extracts the received LLC PDU and available message parameters, relays the PDU to the SGSN via the Gb interface using the BSSGP uplink unit data procedure as per standard GPRS. Upon receiving a downlink packet for the MS 10, the GANC 30 sends the GA-PSR UNITDATA message to the MS using the existing GA-PSR TC. Further, the GANC 30 is arranged to apply 412 a flow control mechanism controlling the downlink transfer in accordance with the data rate information stored during the registration. The data rate informa-

tion may be retrieved for data flow control procedure directly after reception of message 408, or later. During the data transfer, the GANC 30 is configured to control 412 the flow accordingly, for instance by limiting the downlink data transfer rate not to exceed a maximum data rate value supported by the MS 10.

The above-identified 3GPP TS 44.318 discloses further TC channel activation related features in Chapters 8.2 and 8.3, and the GA-PSR user data transport in Chapter 8.7, incorporated herein by reference. It is to be noted that above illustrated features related to registration and data rate indication may be applied in network-initiated data flow establishment, such as for network- initiated GA-PSR TC. Such activation by the GANC 30 is triggered by the downlink GPRS user data request when the corresponding GA-PSR TC does not exist. Features illustrated in Chapter 8.3 of the above-identified 3GPP specification TS 44.318 may be applied in this embodiment, involving transfer of GA-PSR-ACTIVATE-UTC-REQ from the GANC 30 to the MS 10. After TC activation, the GANC 30 is arranged to control the data transfer for the MS in accordance with the data rate information stored during the registration procedure.

During PS domain user plane data transferring GANC 30 controls 410 the down link flow to the MS 10 such that the stored value of down link data rate on MS or PFC level is not exceeded. If the MS has provided maximum data rate information to GANC, the MS may in one embodiment be configured to control uplink flow control such that the uplink data rate on MS or PFC level is not exceeded. When a flow control condition is detected, the MS and the GANC may act according to sub-clause 8.11 and 8.12 of the above- identified 3GPP specification TS 44.318, incorporated herein by reference.

In one embodiment data rate information is transmitted between the network and the communications apparatus by a registration update procedure. In this embodiment the data rate information may be included in a regis- tration update message. Initial data rate information may have already been stored in the network, and a registration update procedure is used to update existing data rate information for a registered communications apparatus. Thus flow control may be dynamically reconfigured. Such a registration update procedure may be started during an active or a non-active data transfer state, i.e. before or after a data transfer context has been established for the registered communications apparatus.

Figure 4b illustrates an embodiment in which the data rate information is transferred from the MS 10 to the GANC 30 by a register update message. In step 450 the MS defines data rate information indicating MS capabilities. A registration update message GA-RC REGISTER UPDATE UPLINK is transmitted 452 to the GANC 30. The GANC 30 is arranged to retrieve the data rate information from the received message and store 454 the information. The GANC 30 is then arranged to control 456 the downlink flow in accordance with the data rate information.

In one embodiment, the features of Figure 4a may precede the sig- naling illustrated in Figure 4b: The GANC 30 may in step 454 change the stored data rate information if the MS 10 provides a new value by sending a GA-RC REGISTER UPDATE. The GANC 30 responds 456 to the update request and adapts 458 the downlink data flow of an already activated GA-PSR TC. The initially set value may be a default value. A registration update procedure, such as the register update procedure of Figure 4b, may be triggered on the basis of a user input or another trigger for modifying existing data rate information stored during registration for controlling data flow, such as changed operating conditions/resource requirements in the communications apparatus. For instance, despite increased power consumption, a user may wish to have a higher bit rate for playing an on-line mobile game, and chooses a higher speed class from a user interface of the MS 10. In response, the MS 10 is arranged to trigger the procedure of Figure 4b to increase allowed maximum download data rate. In another example, to decrease power consumption of the MS 10 in the GAN access mode, a user may be provided with an option to choose a lower bit rate that is used as default for a GAN PS connection. This can be based on predefined power saving profiles, which may be selectable from the user interface of the MS 10. In a further example, in case of GAN Dual Transfer Mode (DTM), the MS 10 may send a new lower value for data rate before traffic channel establishment for a voice call, still ensuring decent voice quality. For instance, this embodiment may be applied in case that the MS performance is not enough to handle simultaneous PS connection and voice call with indicated data rate during registration procedure. After voice call termination the MS 10 may indicate a new higher value to the GANC 30. In case of a PS connection

activation during a CS call, the MS 10 may send a register update uplink with the new data rate value before the traffic channel is established. In another embodiment, already the register request message may comprise the data rate information for DTM operation. As already indicated, the data rate information may indicate a maximum data rate supported by the communications device. However, other kinds of data rate indication formats may be applied. Hence, the entity implementing the method of Figure 4b is configured to arrange the data flow control accordingly. For instance, the data rate information may indicate a data rate, which is preferred for the communications device, and the data flow for the MS 10 is arranged, if possible, in accordance with the preferred rate. Further, a plurality of data rate values may be indicated in the registration message, and applied to data flow control.

In one embodiment a plurality of data throughput classes are speci- fied, and data rate information is indicated by one or more of the classes supported by the communications apparatus. These classes may be used to specify the maximum data rate supported by the apparatus. In a further embodiment such classes represent GAN mobile speed categories supported by the MS 10. For instance, 5 or more classes with suitable spacing could be speci- fied as the GAN mobile maximum bit rate, such as 200 kbit/s, 400 kbit/s, 600 kbit/s, etc. The number of classes could be between 3 and 20, for instance. With such classes it is possible to differentiate and categorize different products into different performance classes and optimize products to support selected classes. When different categories or classes of data rates are com- monly specified, interoperability with devices of different vendors can be enhanced.

In one embodiment the data rate information is included in an information element specifically indicating communications apparatus properties, such as a class mark information element. Such an information element may be included in a registration message, such as in the above illustrated registration messages between the MS 10 and GANC 30.

Figure 5a illustrates an embodiment of a GAN class mark including a field for GAN throughput class (GTC) for indicating data rates supported by the MS 10. The supported data rate(s) may thus be provided to GANC during registration or registration update uplink procedure by including the data rate information in the GAN class mark information element when sending a regis-

tration message, such as the GA-RC REGISTER REQUEST or GA-RC REGISTER UPDATE. The current fields of the GAN class mark information element are explained in Chapter 11.2.7 of the above identified 3GPP TS 44.318, incorporated herein by reference. Figure 5b illustrates in detail one option for specifying data rate information classes. Further, Figure 5b illustrates an option for specifying throughput classes in the GAN class mark information element. It is to be noted that Figure 5b is only one example of possible data rate coding options, and the classes may be defined in many other ways. In one embodiment, the MS 10 may be arranged to initiate a register update procedure when it has registered successfully to the GANC 30 and detects that the MS 10 requires a change to the GAN throughput class included in the GAN class mark information element. The GAN class mark information element is one of the available information elements in the GA-RC REGISTER UPDATE UPLINK message, and is included, if the MS changes GAN throughput class information in the GAN mode. Similarly, the GAN class mark information element may be added as a new information element in the GA-RC REGISTER REQUEST message, the current information elements of which are illustrated in Chapter 6.2.1 of the above-identified 3GPP specification TS 44.318.

It is to be noted that Figures 3a to 3c, 4a, 4b, 5a, and 5b illustrate only some possible implementation options, and there are many other implementation options available. For instance, the features of Figure 3b may be provided by two or more interconnected devices. A further example is that a first network element receives the registration message and registers the communications device, and a second one arranges the data flow control based on the data rate information from the first network element. Some other embodiments illustrated below may be applied in connection with or independently of the above illustrated embodiments. In one embodiment, a registration update uplink message with a new data rate value is transmitted when the PS traffic channel is active. For instance, the GA-RC REGISTER UPDATE message may be used to carry the data rate information to be updated to the GANC 30 after activation of the UTC in the GAN system. This enables the network device (30) to change the ap- plied data transmission rate if the terminal communications apparatus (10) detects problems in receiving data transmitted by the initially registered data rate.

According to an embodiment, the data rate information is transferred in some other message, i.e. a message not related to registration or registration update, preceding user plane data transfer. This embodiment may be applied instead or in addition to transmitting the data rate value in the registration messages. Some further examples of this embodiment are illustrated below.

In a further embodiment, as illustrated in Figure 4c, the data rate value is transmitted between the MS 10 and the GANC 30 in GA-PSR layer messages during the Transport Channel (GA-PSR TC) activation phase. Thus, the MS 10 may be configured to include the data rate value in a GA-PSR- ACTIVATE-UTC-REQ message 472. The GANC 30 is arranged to retrieve the data rate information, which may be stored. The GANC 30 acknowledges the request by GA-PSR ACTIVATE USR ACK 474. The GANC 30 is arranged to control 476 the downlink flow in accordance with the data rate information. In one embodiment the message 472 specifies a maximum downlink data rate value.

In case of network-initiated GA-PSR TC activation, the MS 10 may include data rate information in GA-PSR-ACTIVATE-UTC-ACK. On the basis of the data rate value encoded in such a transport channel activation message, the GANC 30 is arranged to adapt the data flow control for the channel accord- ingly. The above-illustrated information elements may be applied for encoding the data rate information in GA-PSR (or CSR) layer messages, for instance the data rate information may be included in a GAN class mark information element. The above non-registration specific features may be applied also to the embodiment using connection establishment messages for indicating the data rate information, for instance in Figures 3a to 3c the registration/deregistration related features could be removed and replaced by connection establishment/removal related features and messages.

As illustrated in Figure 6a, a communications apparatus in general, and the mobile station 10 apparatus illustrated in Figure 1 , comprise one or more units 606 for radio frequency (RF) communications (transmitter, receiver, transceiver) enabling the communication in accordance with the radio access technology or technologies supported by the MS. The MS 10 also includes a user interface 604 for user input/output. The operation of the MS 10 and various elements thereof is controlled by one or more control units 600 (such as a micro controller, microprocessor, or any other programmable device) having an associated memory 602 for storing data and software.

Figure 6b illustrates basic elements of a network element apparatus configured to communicate with a mobile terminal apparatus, which may be the GANC 30. Such apparatus comprises one or more control units 650, memory 652, and communications unit(s) 654. Computer program code portions 608, 658 stored in the memories

602 and executed in the processing unit 600, 650 may be used for causing the device MS 10 and the GANC 30, respectively, to implement a method and means for providing the inventive functions relating to arranging connection establishment in an environment with multiple radio access technologies, some embodiments of the inventive functions were illustrated above in association with Figures 3a, 3b, 4a, 4b, 4c, 5a, and 5b.

A control entity may be provided in the MS 10 to control registration and in particular inclusion of the data rate information in registration messages to the GANC 30. This control entity may be provided by a GA-RC protocol layer control entity. Also the GANC 30 is provided by one or more control entities implementing at least some of the above-illustrated features in the GANC 30. Such a control entity may be provided by a GA-RC and/or GA-PSR protocol entity, for instance. For instance, a GA-RC entity may handle registration/transport channel activation message reception related features and a GA- PSR entity may handle following data flow control related features on the basis of the received data rate information. Hence, by interaction of logical entities in the MS 10 and in the GANC 30 it is possible to implement the above-illustrated features. These entities may be implemented by the execution of a stored program code 608 in a processing unit 600 in the MS 10, and by a stored program code 656 in a processing unit 600 in the GANC 30, for instance.

The above illustrated functions by the MS 10 and the GANC 30, implemented by the controlled co-operation between the units of Figure 6a and 6b, can also be considered to represent logical (sub-)units that implement the related features for arranging data flow control by applying registration mes- sages, as illustrated in Figures 3a and 3b, for instance. Hardware solutions or a combination of software and hardware solutions may also be used. A chip unit or some other kind of module for controlling the device MS 10 and/or the GANC 30 may, in one embodiment, cause the device to perform the inventive functions. Such module comprises an interface for connecting to the device mechanically and/or functionally. Thus, the module may form part of the device and could be removable. One example of such a module is a sub-assembly.

Embodiments related to the 3GPP GAN system were illustrated above. As already indicated, the present solution may be applied in other systems, where network technology is independent radio access. An example of such a system is a WLAN-3GPP interworking system, where a WLAN is used to access a 3GPP network. A mobile station registering to such an interworking system may be arranged to transmit the data rate information in a registration (update) message to ensure interoperability. A network element controlling data flow may thus adapt data flow properties in accordance with the data rate information detected in the received registration message. Another example is a system where a mobile station accesses an IP multimedia subsystem (IMS) over a WLAN or over some other radio access. The mobile station may be arranged to inform the network of the data rate by a registration (update) or a transport channel activation related message, and the network may control data flow accordingly. It is obvious to a person skilled in the art that as technology advances, the basic idea of the invention can be implemented in a variety of ways. The invention and its embodiments are thus not limited to the above examples, but may vary within the claims. Different features may thus be omitted, modified or replaced with equivalents. The combinations of claim elements as stated in the claims can be changed in a number of different ways and still be within the scope of various embodiments of the invention.