HK1138982B - Method for considering the subscriber type in mobility and radio resource management decisions in a radio access network - Google Patents

Description

Method for considering subscriber type in making mobility and radio resource management decisions in a radio access network

Background

With the increasing standardization of 3GPP long term evolution (LTE or E-UTRAN) and WiMAX (IEEE802.16) air interfaces, the diversity of Radio Access Technologies (RATs) will increase in the future beyond the existing standards (GSM/gprs and umts), and operators will need sophisticated mobility mechanisms to distribute the load through these different technologies while delivering users to the appropriate RAT.

In today's wireless systems, such as GSM/GPRS or UMTS, a typical UE-controlled cell reselection algorithm is currently operating independently of any particular subscriber or service selection [ for UMTS, e.g. in 3gpp ts25.304 ]. All UEs are handled in the same way [ for UMTS, e.g. in 3gpp ts25.331 ] based on the parameters broadcast on the BCCH, and therefore follow the same cell reselection strategy. Similar to idle mode, the decision criteria for mobility related and radio resource related decisions are independent of any subscriber or user type messages. So, in general, the decision is based on the terminal capabilities and to some extent on the current service usage or specific information provided by the CN during the establishment of the current service (e.g. so-called "service based handover", which gives an indication that a certain bearer sent from the CN to the RAN is to be handed over to a specific RAT or not). These are all related to the need to provide an equal service to all users of a mobile system.

With the emergence of the need for enhanced data rates and reduced costs implied by the particular tariffs of mobile operators, it is anticipated that the need for user and service partitioning, for example in mobility decisions, will increase. Data defined in terms of quality of service (QoS) may provide some means of partitioning subscribers, but mobility-related decisions (especially when in idle mode) cannot be made reliably based on information designed to partition traffic of different services using prioritized packet transmission rather than independent customized ways of controlling mobility based on user type.

3GPP has specified access control classes to restrict only a group of subscribers belonging to a group of access control classes from having access to a mobile network during periods of severe congestion in the network. It is proposed that similar properties of user partitioning can be used in the RAN for mobility decisions so that users can be properly dispersed across RATs.

In addition to load distribution by RAT, similar mechanisms are also needed to distribute load with different carriers of different bandwidths on the same RAT.

EP1519607 discloses a method and apparatus for radio resource management, wherein the method includes allowing a radio access network to selectively influence mobility decisions and radio resource control decisions for a particular terminal based on information received from a core network entity.

US2002, 0193139a1 discloses a method of selecting a network, cell or interface in a hybrid network in which a mobile terminal may select different modes of operation, each mode of operation corresponding to one of a plurality of core networks. The selection is made based on selection parameters provided to the mobile terminal by broadcast system information or packet system information in the radio cell.

Summary of The Invention

It is proposed to give a procedure in which an entity of the CN (e.g. an aGW in case of SAE/LTE) informs the radio access network (e.g. an eNB in case of LTE/SAE) of subscriber specific information when registering a UE or when transitioning from LTE idle to LTEACTIVE state, which is then taken into account in making mobility decisions and radio resource management decisions in the radio access network, whether in idle mode or active mode. This information is preferably defined as an integer that is closely related to the specific processing of the UE as defined by a set of rules. These rules will be defined locally in an eNB (or any other involved node) according to a configuration file (e.g. in a mainstream data format like XML, etc.) and will be applied by the eNB during mobility and radio resource management.

Detailed description of the invention

Upon registration of a UE or during a transition from LTE _ IDLE state to LTE _ ACTIVE state (see fig. 1), the signaling sent by the CN (200) to the RAN (201) will include a new "subscriber type" information element (in 301) that can be used by the network (302) in mobility or other radio resource management decisions. The "subscriber type" message element may also be sent to that UE so that the UE can also allow user partitioning (e.g., for cell reselection purposes) in a terminal-based decision by broadcasting (on the BCCH) only according to a specific portion of the system information.

The coding of the information element should be flexible enough to allow its application within a variety of mobility applications. To give sufficient granularity, it is recommended to define at least 16 levels.

Fig. 2 illustrates one embodiment of using the user type field between UMTS and lte rat to balance the load. Assuming the LTE load is greater than a given threshold, it is desirable to spread users across multiple RATs based on the difference in the services used and the subscriber type.

Some services requiring particularly high data rates or minimal delay are better suited to be handled on the higher performance LTERAT, independent of the subscriber type. However, most services are better handled on both higher and lower ranked RATs, and RAT selection for these services is based primarily on the subscriber type. In this embodiment 8 levels of subscriber types are listed (the number limitation is for illustrative purposes only), and for 3 subscriber types most of the service options are handled on UTMS instead of lte rat. Having subscriber type as the optimal criterion instead of service type reduces the number of inter-RAT moves triggered by the use of different services and also allows a more fixed RAT selection strategy to be employed in idle and active modes (fig. 2).

The number of subscriber type classes selected to be handled on the UMTS or lte RAT may be set according to the load levels in both RATs. In the case of low LTE load operation, it is beneficial to handle all users with better performance LTE rat. In the case of high load operation, the number of subscriber type classes introduced on different RATs may vary depending on the relevant load situation on the two RATs.

Another embodiment of subscriber type information used in mobility decisions for a cellular network is in the case of network sharing or national roaming. In this example, it is characteristic that the RAT (e.g. LTE) is shared between different mobile operators, while the technology is not shared by legacy networks (e.g. UMTS or GSM). Typically, the operator is interested in getting his own users back to his network at any time. For example, if leaving the coverage of the shared LTE network, the own user should preferably be handed over to the correct target network, although both may meet the requirements of a HO target in terms of radio conditions. In this example, a "subscriber type" indication received from the CN may be used to bring the correct user to the correct network. Today this requirement can only be met by analyzing the specific identity of an operator available in the RAN (i.e. the IMSI available in the RNC in UMTS, but not in the BSC of the GSM network). Defining a RRM rule in the decision node that always performs a handover of subscriber type X (from PLMNB) back to PLMNB would be very flexible and could be enhanced/changed based on any registration information available in the CN without any changes to existing RAN implementations. Furthermore, the fact that there is no subscriber specific information in some nodes of a network that are vulnerable (e.g., the complete IMSI of a user that can identify the identity of the user) is also beneficial to security. Having only the "subscriber type" profile information available and the "processing rules" defined can ensure confidentiality of these users in all cases.

Another application using "subscriber type" information may be associated with a specific usage condition of a terminal in a cellular network. For example, today, in all cellular networks, the decision function in the network/RAN does not have any such information about how a particular terminal is used. For example, the network with simple means cannot detect, for example, whether a terminal is a fixed device such as part of a machine or a wireless gateway router. Currently, the only way to obtain this information is either to introduce a specific signaling or to determine if a terminal is stationary or not using radio measurements. In particular, the operation of a network with fixed wireless gateway routers (enabling wireless access to the internet for small home or office networks), and with fixed machine-to-machine devices (gas/water meters) can benefit from the additional information about the fact that the device is neither mobile, nor does it have strict energy constraints because it is typically connected to a fixed power supply: the network may take specific actions for such devices that are not applicable to most mobile devices in the cellular network. An embodiment is that a specific timer may be employed for the LTE _ ACTIVE to LTE _ IDLE state transition (for releasing resources or bringing the device into a state of low energy consumption operation) or the network may completely disable any measurements for mobility to be applied by the device, since it does not need to perform handover to a different cell at all. The above listed embodiments are not exclusive and any one may consider even more scenarios where such information about the user type is beneficial.

Claims (21)

1. A method of handling a radio access network, RAN, (201) to have selectively influence mobility decisions and radio resource control decisions for a specific mobile terminal based on subscriber specific information (301) received from a core network, CN, (200) entity, characterized by: the subscriber specific information (301) provided from the CN (200) to the RAN (201) comprises only summary subscriber type information in the form of an indexed subscriber type identifying one of a plurality of subscriber type levels, and wherein the subscriber specific information (301) is associated with "processing rules" defining how the mobile terminal is to be processed, wherein said indexed subscriber type points to locally defined processing rules in each involved network node; the indexed subscriber types are used to balance load across different Radio Access Technologies (RATs), and when network load on a radio access technology is greater than a given threshold, users are spread across multiple RATs based on the services used and the subscriber type.

2. A method according to claim 1, wherein the CN (200) provides subscriber specific information to the RAN (201) when registering a mobile terminal.

3. A method according to claim 1, wherein the CN (200) provides the RAN (201) with subscriber-specific information upon a transition of the mobile terminal from idle mode to active mode.

4. A method according to claim 1, wherein the CN (200) selects the appropriate index "subscriber type" in the information available from the home location register HLR.

5. A method according to claim 1, wherein the CN (200) selects the appropriate index "subscriber type" in the information available from the CN.

6. A method according to claim 1, wherein the CN (200) selects the appropriate index "subscriber type" from information not related to subscription, but related to mobile terminal capabilities.

7. A method according to claim 1, wherein the CN (200) selects the appropriate index "subscriber type" in information available from a source other than the CN (200).

8. A method according to claim 1, wherein the CN (200) selects the appropriate index "subscriber type" from information depending on the user selection.

9. A method according to claim 1, wherein the CN (200) selects the appropriate index "subscriber type" in the information available from the usage history of the mobile subscriber.

10. A method according to claim 1, wherein the CN (200) sends the subscriber specific information (301) to the RAN (201) in a message identical to the message triggering the transition of the mobile terminal from idle to active.

11. A method according to claim 1, wherein the configuration of the "processing rules" is defined locally in each involved node by a protocol specifically used for this purpose.

12. A method according to claim 1, wherein the processing rules depend on subscription information requested from the home location register, HLR, and on service and load.

13. A method according to claim 1, wherein the processing rules depend on subscription information requested from a policy and charging rules function, PCRF, and on service and load.

14. A method according to claim 1, wherein the processing rules depend on a user's priority, and on service and load.

15. A method according to claim 14, wherein the processing rules depend on the history of user behaviour, and on service and load.

16. A method according to claim 14, wherein the processing rules depend on the type of terminal used by the user, said types including mobile devices, laptops, home wireless access points, vending machines, machine-to-machine devices; and on service and load.

17. A method according to claim 1, wherein the "subscriber type" information is used as signalling to the mobile terminal to determine which part of the system information of the broadcast control channel BCCH is to be used by the mobile terminal to apply the partitioned mobility decisions or procedures.

18. A radio access network, RAN, (201) comprising means for selectively influencing mobility decisions and radio resource control decisions for a specific mobile terminal based on subscriber specific information (301) received from a core network, CN, (200) entity, characterized by: the subscriber specific information (301) comprises only summary subscriber type information in the form of an index subscriber type and the index subscriber type is associated with a "processing rule" defining how the mobile terminal is to be processed, wherein the configuration of the "processing rule" is defined locally in each involved node; the defined "processing rules" play a role during the making of mobility and radio resource management decisions and send information to selected mobile terminals that allows these terminals to optionally read system information on the broadcast control channel BCCH for cell reselection purposes.

19. The radio access network RAN (201) of claim 18, characterized in that: the defined "processing rules" function according to the indexed "processing rules" for mobile devices in active mode during making mobility and radio resource management decisions.

20. The radio access network RAN (201) of claim 18, characterized in that: it acts according to indexed "processing rules" for mobile devices in idle mode during mobility and radio resource management decisions; to do this, the RAN will identify and group mobile devices and assign "processing rules" to these mobile devices belonging to the same subscriber group.

21. The radio access network RAN (201) of claim 18, characterized in that: there are defined "processing rules" that include providing different "mobility rules" by assigning different sets of cell reselection parameters to different groups of UEs, depending on the subscriber information or indices available to each UE.