WO2013000516A1

WO2013000516A1 - Congestion detection and control

Info

Publication number: WO2013000516A1
Application number: PCT/EP2011/060984
Authority: WO
Inventors: Juha Antero Rasanen
Original assignee: Nokia Siemens Networks Oy
Current assignee: Nokia Solutions and Networks Oy
Priority date: 2011-06-30
Filing date: 2011-06-30
Publication date: 2013-01-03
Anticipated expiration: 2013-12-30

Abstract

An apparatus is described which comprises a controller configured to perform policy control function, monitor at least one session related to a network element, and perform congestion control based on the at least one monitored session.

Description

Description Title

Congestion detection and control Field of the Invention

The present invention relates to apparatuses, methods and a computer program product for performing congestion detection and control.

Related background Art

The following meanings for the abbreviations used in this specification apply:

3GPP 3^rd generation partnership project

AF Application function

BBERF Bearer binding and event reporting function

DRA Diameter routing agent

eN B Evolved Node-B, LTE base station

EDGE Enhanced data rates for GSM evolution

E-UTRAN Evolved universal terrestrial radio access network

GBR Guaranteed bit flow

GERAN GSM EDGE radio access network

GSM Global system for mobile communications

GW Gateway

HSS Home subscriber server

I D Identifier

IMS I P multimedia subsystem

I P Internet protocol

I P-CAN I P connectivity access network

LTE Long term evolution

MME Mobility management entity

PCC Policy and charging control

PCEF Policy and charging enforcement function

PCRF Policy and charging rules function

PDN Packet data network

P-GW Packet data network gateway

PSS Packet switched service QoS Quality of service

SDF Service data flow

S-GW Serving gateway

SID Study item description

SPR Subscription profile repository

TR Technical report

UDR User data repository

UE User equipment

UTRAN Universal terrestrial radio access network

Embodiments of the present invention relate to user plane congestion management. The embodiments of the invention may enable more efficient usage of network resources.

Recently a significant increase in data traffic could be seen by mobile operators. Although the traffic carrying capacity of networks has increased significantly, the increased traffic nevertheless resulted in increased network congestion. Therefore, there is a need to decrease network congestion.

One or more embodiments of the invention may relate to

• Mechanisms to allow the system to improve the network performance by taking into consideration conditions and status in the network, e.g. by manipulating QoS related policy enforcement while taking into account network loading.

• Identifying specific information which can be used to represent the network conditions and status.

• Identifying the network entities and/or parts suffering from congestion.

• Managing congestion information with a better granularity than a plain binary "yes/no".

That is, preferably the granularity of the congestion information should be increased beyond the current binary "yes/no" indication (in order to be able to manage congestion situations more flexibly and efficiently).

• Making relevant congestion information available for an entity that is able to manage and control required QoS and bearer management activities, wherein this should be effected without adding extra signalling load in the network.

• Detecting how the network entities and/or parts suffering from congestion identified.

And related to this, it should be considered how can proper measures to relieve the congestion be focused to the correct spot/area. Possible solutions are not expected to add extra load (especially signalling load) to the network. In an exemplary prior art solution, a eN B sends congestion information by certain intervals to PCRF, and PCRF utilises that info. So, each element to be controlled needs to send the congestion info to PCRF at certain intervals which requires considerable network traffic and increases the network load, which would be contradictory to the aim to reduce congestion.

Summary of the Invention

Embodiments of the present invention aim to provide to overcome the problems discussed above and to enable congestion detection and control without increasing network load.

According to a first aspect of the present invention, an apparatus is provided which comprises a controller configured to perform a policy control function, monitor at least one session related to a network element, and perform congestion control based on the at least one monitored session.

According to a further aspect, a method is provided which comprises performing a policy control function, monitoring at least one session related to a network element, and performing congestion control based on the at least one monitored session. Brief Description of the Drawings

These and other objects, features, details and advantages will become more fully apparent from the following detailed description of embodiments of the present invention which is to be taken in conjunction with the appended drawings, in which:

Fig. 1 shows a basic structure of a PCRF according to an embodiment of the present invention,

Fig. 2 shows a non-roaming architecture for 3GPP accesses, in which the arrangement of a PCRF is illustrated, Fig. 3 shows operations when a new IP-CAN session is established and the level of congestion and/or required actions threshold is reached for a given network element according to an embodiment of the present invention, and Fig. 4 illustrates the basic structure of a DRA as a master network control element for a plurality of PCRFs.

Detailed Description of embodiments In the following, description will be made to embodiments of the present invention. It is to be understood, however, that the description is given by way of example only, and that the described embodiments are by no means to be understood as limiting the present invention thereto. According to several embodiments of the present invention measures are provided by which congestion in a network can be controlled. In particular, a method and an apparatus are provided, which perform a policy related control, and which monitor at least one session related to a network element and perform congestion control based on the at least one monitored session.

An example for such an apparatus according to an embodiment is shown in Fig. 1. The apparatus may be a network control element relating to policy and charging control (e.g., a PCRF) or a part thereof. As shown, the PCRF comprises an interface 1 1 , which provides a connection to a network, a controller 12 which carries out a policy related control, monitors the at least one session related to a network element and performs a congestion control as mentioned above, and a memory 13, in which several programs and data for carrying out the functions according to the embodiment are stored. The interface 1 1 , the controller 12 and the memory 13 may be inter-connected by a suitable connection 14, e.g., a bus or the like.

Thus, according to embodiments of the invention, a network element which carries out a policy related control also monitors sessions of a network element. In this way, impacts on other network elements and signalling between them can be minimized to or close to zero. Monitoring can be effected such that, when the apparatus receives a request for a session, the apparatus binds this session to records related to the network element. With respect to Fig. 1 , such a request can be received via the interface 1 1 . Furthermore, sessions of a plurality of network elements can be monitored, and some network elements can be considered in a combined manner. Hence, sessions of a group of network elements as a network part can be monitored in combination, so that a congestion control can be effected with respect to this network part or group of network elements.

According to several embodiments of the present invention, the apparatus described above may be provided within a network control element such as a PCRF. The arrangement of the PCRF within the 3GPP architecture reference model is described in the following by referring to Fig. 2, which reproduces Fig. 4.2.1 -1 of 3GPP TS 23.401 V10.5 (201 1 -06) and illustrates the non-roaming architecture for 3GPP accesses.

As shown, the PCRF is connected with a PDN Gateway, wherein a Gx reference point is defined between the PCRF and the PDN Gateway. Moreover, the PCRF is also connected to operator's IP services (e.g., IMS, PSS etc.), wherein on this connection an Rx reference point is defined. The PDN Gateway is connected with a Serving Gateway, which in turn is connected via E-UTRAN to the UE. Between the PDN Gateway, a reference point S5 is defined, which provides e.g., user plane tunnelling and tunnel management. Between the Serving Gateway and E-UTRAN, a reference point S1 -U is defined for the per bearer user plane tunnelling and inter eNodeB path switching during handover. Between the UE and E-UTRAN, a reference point LTE-Uu is defined.

For further detailed descriptions it is referred to the above-mentioned 3GPP TS 23.401 V10.5 (201 1 -06). In the following, a detailed embodiment of the present invention is described by referring to Fig. 3.

In particular, according to this embodiment, the PCRF keeps track on IP-CAN sessions and especially on related authorized and active service data flows (SDFs) related to, i.e. using, congestion critical network elements. The PCRF may identify the elements by an identity (e.g. a radio cell identifier) and/or by a network element IP address information received from the PCEF/BBERF upon an IP-CAN session establishment or modification. The actual storage for the information may be within the PCRF or a PCRF external database. The PCRF aggregates the resource requirements (typically bit rates) of the authorized SDFs of all IP-CAN sessions using a given (congestion critical and thus configured to be under surveillance) network element, e.g. a radio base station or a gateway or a part / direction / route of a gateway. The aggregation may be done by QoS class, for example, guaranteed bit rate (GBR) flows may be aggregated as one group (or even as multiple subgroups), because they need guaranteed bearer resources for known bit rates. A part / direction / route of a gateway may be within the operator's network or from the operator's network gateway towards an external packet data network (PDN).

Moreover, the PCRF uses network element or part specific/related reference information (e.g. simply a maximum aggregated data rate, possibly related to a QoS class, the element can handle) to compare the aggregated resource requirements of the authorized SDFs with, and to deduce the grade of load in the network element or part, i.e. to deduce how close to congestion and/or to required actions threshold the network element or part is. The network element or part specific/related reference information may be configured at the PCRF or may be available to the PCRF from a PCRF external source. The network part mentioned above may include a plurality of network elements, but also only a part of a network element, such as a part, direction or route of a gateway, as mentioned above.

When the grade of load in a network element or part reaches the level of congestion and/or required actions threshold, the PCRF may apply already known measures, like preemption based on prioritization, or downgrading QoS (especially bit rate) for sessions which have reported a high usage, or rejecting new requests, or any to-be-specified congestion handling/alleviation measures, to IP-CAN sessions or to SDFs of IP-CAN sessions using the network element or part.

Fig. 3 describes the operations when a new IP-CAN session is established and the level of congestion and/or required actions threshold is reached for a given network element:

S1 : A UE attaches to the network and a default bearer is established for the IP-CAN session. S2: The PCEF requests authorization for the default bearer from the PCRF. In addition to the regular parameters, the request contains identities and/or IP addresses of network elements/entities or parts of network elements/entities. S3: PCRF binds the new IP-CAN session to element/entity records (to keep track on the total loading status vs. the maximum reference value(s) of each element/entity) and updates the aggregated QoS requirements for each record with possible QoS

requirements of the new IP-CAN session. S4: PCRF sends a response to PCEF.

S5: PCEF sends a response towards the UE.

S6: The UE establishes an application session with a counterpart. Related to the session establishment, the AF sends a request with session parameters to the PCRF.

S7: PCRF binds the AF session to the IP-CAN session of the UE and checks

(loading/congestion) status from the related element/entity records. If there is congestion in some element/entity, the PCRF activates congestion management measures, and, depending on the extent of this congestion management measures, the following steps S9 - S13 may not take place.

S8: PCRF sends a response to AF. S9: PCRF sends a request with PCC/QoS Rules for the service data flow(s) (SDF) to the PCEF.

S10: PCEF establishes a bearer for the new SDF (or modifies an existing bearer). S1 1 : UE sends a response to PCEF.

PCEF sends a response to PCRF.

S13: PCRF updates the IP-CAN session related element/entity records, if there are related requirements in the response message. If there are more than one PCRFs in the network, the required coordination between PCRFs may be managed by a master network control element such as a diameter routing agent (DRA) (a kind of master or manager PCRF) that will anyway, as per current 3GPP specifications, be involved in IP-CAN session establishments and related communication between the PCRF clients (e.g. PCEF/BBERF) and the selected PCRF. The DRA may maintain the loading/congestion grade/status information of the network elements under surveillance and even the network element or part specific/related reference information.

An example for a DRA is illustrated in Fig. 4. The DRA 2 comprises an interface 21 , which provides a connection to a network, a controller 22 which carries out managing the plurality of the network control elements (such as PCRFs) described above, and a memory 23, in which several programs and data for carrying out the functions according to the embodiment are stored. The interface 21 , the controller 22 and the memory 23 may be inter-connected by a suitable connection 24, e.g., a bus or the like.

Each PCRF may update the loading/congestion information upon I P-CAN session establishments, modifications and/or terminations in which they are involved themselves, and may correspondingly get updated information caused by other PCRFs, and apply the updated information to avert or handle or alleviate congestion.

The PCRF causing the reaching of congestion and/or a required actions threshold (e.g. upon a new IP-CAN session establishment or a modification of an I P-CAN session) may be obliged to activate required measures to handle the situation, in order to avoid a need to signal the situation to other PCRF(s) in the network.

Thus, according to the embodiments described above, a PCC based solution is provided, in which impacts on other network elements and signalling between them is minimized to or close to zero. As mentioned above, a PCRF keeps track on I P-CAN sessions and especially on related authorized and active service data flows (SDFs) related to, i.e. using, congestion critical network elements. In this way, the PCRF analyses element by element the load situation by monitoring how much bit rate/ bandwidth the PCRF itself has allocated/authorised for the data flows handled by each of the elements. The PCRF utilises the identifiers of the elements (e.g. I D, I P address) and the maximum reference value of each element. In this way, the PCRF can deduce how close to congestion and/or to required actions threshold the network element or part is by keeping track on the total loading status vs. the maximum reference value(s) of each element/entity.

When the grade of load in a network element or part reaches the level of congestion and/or required actions threshold, the PCRF may apply congestion control or counter- congestion measures to IP-CAN sessions or to SDFs of IP-CAN sessions using the network element.

As mentioned initially, in an exemplary prior art solution eNB sends congestion information by certain intervals to PCRF and PCRF utilises that info. So, each element to be controlled needs to send the congestion info to PCRF at certain intervals which is hard, burdening and bulky mechanism compared to the above-described embodiments of the invention. According to the embodiments of the present invention, the elements need not to send congestion information to PCRF.

Thus, according to embodiments of the present invention, a congestion detection and control is achieved which require only limited signalling.

The invention is not limited to the embodiments described above.

For example, according to the embodiments described above, a PCRF is a network control element which carries out the function of monitoring sessions in the network. However, this is only an example. That is, although it is advantageous to provide this function in a PCRF, it is nevertheless possible to provide this function in another network control element separately which performs a policy related control.

Moreover, according to embodiments described above, a DRA is used for managing a plurality of PCRFs. However, also another suitable network control element may be used. Furthermore, according to embodiments described above, the term "network element" is used for describing network nodes such as base stations, gateways and the like.

However, it is noted that this term includes any kind of network entity which may be involved in a session. For example, also a whole cell or group of cells can be considered. According to a first aspect of several embodiments of the invention, an apparatus is provided which comprises a controller configured to

perform a policy control function,

monitor at least one session related to a network element, and

perform congestion control based on the at least one monitored session.

The first aspect may be modified as follows:

The controller may be configured to receive a request for the session, and to bind the session to records related to the network element.

The controller may be configured to identify the network element based on an identity and/or IP address information of the network element received from a network control element upon establishment or modification of the at least one session. The controller may be configured to monitor a plurality of sessions, and to aggregate resource requirements of all sessions using the network element.

The controller may be configured to perform the aggregation based on a quality of service class.

The controller may be configured to compare the aggregated resource requirements with reference information, and to deduce load condition on the network element and/or a network part based on the comparison. The controller may be configured to perform congestion control by applying counter- congestion measures when it is determined that a load on the network element and/or the network part exceeds a threshold set based on the reference information.

The controller may be configured to monitor sessions of a group of network elements.

The network part mentioned above may comprise a group of network elements or a part of the network element, and the reference information may be set for the network part.

For example, the part of the network element mentioned above could include a part, direction or route of a gateway. The reference information, and thus the threshold mentioned above may be set for the network part. That is, a single threshold may be applied for a whole group of network elements, for example. The apparatus according to the first aspect and its variations may be a network control element, a policy and charging rules function or a part thereof.

According to a second aspect of several embodiments of the invention, an apparatus is provided which comprises

a controller configured to manage a plurality of network control elements comprising an apparatus according to the first aspect and its variations.

According to a variation of the second aspect, the controller may be configured to perform an exchange of congestion information and/or reference information and/or information regarding a threshold set based on the reference information between the network control elements.

According to a third aspect of several embodiments of the invention, a method is provided which comprises

performing a policy control function,

monitoring at least one session related to a network element, and

performing congestion control based on the at least one monitored session.

The third aspect may be modified as follows:

The method may further comprise receiving a request for the session, and binding the session to records related to the network element.

The method may further comprise identifying the network element based on an identity and/or IP address information of the network element received from a network control element upon establishment or modification of the at least one session.

The method may further comprise monitoring a plurality of sessions, and to aggregate resource requirements of all sessions using the network element. The method may further comprise performing the aggregation based on a quality of service class.

The method may further comprise comparing the aggregated resource requirements with reference information, and deducing load condition on the network element and/or a network part based on the comparison.

The method may further comprise performing congestion control by applying counter- congestion measures when it is determined that a load on the network element and/or the network part exceeds a threshold set based on the reference information.

The method may further comprise monitoring sessions of a group of network elements.

The network part may comprise a group of network elements or a part of the network element, and the reference information may be set for the network part.

For example, the part of the network element mentioned above could include a part, direction or route of a gateway. The reference information, and thus the threshold mentioned above may be set for the network part. That is, a single threshold may be applied for a whole group of network elements, for example.

The method according to the third aspect and its variations may be carried out by a network control element, a policy and charging rules function or a part thereof.

According to a fourth aspect of several embodiments of the invention, a method is provided which comprises

managing a plurality of network control elements carrying out the method according to the third aspect and its variations.

According to the fourth aspect, the method may further comprise

performing an exchange of congestion information and/or reference information and/or information regarding a threshold set based on the reference information between the network control elements. The method according to the fourth aspect and its variations may be carried out by a master network control element, a diameter routing agent or a part thereof.

According to a fifth aspect of several embodiments of the invention, a computer program product is provided which comprises code means for performing a method according to any one of the third and fourth aspects and their variations when run on a processing means or module.

The computer program product may be embodied on a computer-readable medium.

According to a sixth aspect of several embodiments of the invention, an apparatus is provided which comprises

means for performing a policy control function,

means for monitoring at least one session related to a network element, and means for performing congestion control based on the at least one monitored session.

The sixth aspect may be modified as follows:

The apparatus may further comprise means for receiving a request for the session, and binding the session to records related to the network element.

The apparatus may further comprise means for identifying the network element based on an identity and/or IP address information of the network element received from a network control element upon establishment or modification of the at least one session.

The apparatus may further comprise means for monitoring a plurality of sessions, and to aggregate resource requirements of all sessions using the network element.

The apparatus may further comprise means for performing the aggregation based on a quality of service class.

The apparatus may further comprise means for comparing the aggregated resource requirements with reference information, and deducing load condition on the network element and/or a network part based on the comparison. The apparatus may further comprise means for performing congestion control by applying counter-congestion measures when it is determined that a load on the network element and/or the network part exceeds a threshold set based on the reference information. The apparatus may further comprise means for monitoring sessions of a group of network elements.

Moreover, similar variations as described in connection with the first aspect are also possible for the sixth aspect.

According to a seventh aspect of several embodiments of the invention, an apparatus is provided which comprises

means for managing a plurality of apparatuses as defined according to the sixth aspect and its variations.

According to the seventh aspect, the apparatus may further comprise

means for performing an exchange of congestion information and/or reference information and/or information regarding a threshold set based on the reference information between the network control elements.

Moreover, similar variations as described in connection with the first and second aspects are also possible for the sixth and seventh aspects.

It is to be understood that any of the above modifications can be applied singly or in combination to the respective aspects and/or embodiments to which they refer, unless they are explicitly stated as excluding alternatives.

For the purpose of the present invention as described herein above, it should be noted that

- method steps likely to be implemented as software code portions and being run using a processor at a network element or terminal (as examples of devices, apparatuses and/or modules thereof, or as examples of entities including apparatuses and/or modules therefore), are software code independent and can be specified using any known or future developed programming language as long as the functionality defined by the method steps is preserved; - generally, any method step is suitable to be implemented as software or by hardware without changing the idea of the invention in terms of the functionality implemented;

- method steps and/or devices, units or means likely to be implemented as hardware components at the above-defined apparatuses, or any module(s) thereof, (e.g., devices carrying out the functions of the apparatuses according to the embodiments as described above, PCRF, DRA etc. as described above) are hardware independent and can be implemented using any known or future developed hardware technology or any hybrids of these, such as MOS (Metal Oxide Semiconductor), CMOS (Complementary MOS), BiMOS (Bipolar MOS), BiCMOS (Bipolar CMOS), ECL (Emitter Coupled Logic), TTL (Transistor-Transistor Logic), etc., using for example ASIC (Application Specific IC

(Integrated Circuit)) components, FPGA (Field-programmable Gate Arrays) components, CPLD (Complex Programmable Logic Device) components or DSP (Digital Signal Processor) components;

- devices, units or means (e.g. the above-defined apparatuses, or any one of their respective means) can be implemented as individual devices, units or means, but this does not exclude that they are implemented in a distributed fashion throughout the system, as long as the functionality of the device, unit or means is preserved;

- an apparatus may be represented by a semiconductor chip, a chipset, or a (hardware) module comprising such chip or chipset; this, however, does not exclude the possibility that a functionality of an apparatus or module, instead of being hardware implemented, be implemented as software in a (software) module such as a computer program or a computer program product comprising executable software code portions for

execution/being run on a processor;

- a device may be regarded as an apparatus or as an assembly of more than one apparatus, whether functionally in cooperation with each other or functionally

independently of each other but in a same device housing, for example.

It is noted that the embodiments and examples described above are provided for illustrative purposes only and are in no way intended that the present invention is restricted thereto. Rather, it is the intention that all variations and modifications be included which fall within the spirit and scope of the appended claims.

Claims

1 . An apparatus comprising

a controller configured to

perform a policy control function,

monitor at least one session related to a network element, and

perform congestion control based on the at least one monitored session.

2. The apparatus according to claim 1 , wherein

the controller is configured to receive a request for the session, and

the controller is configured to bind the session to records related to the network element.

3. The apparatus according to claim 1 or 2, wherein

the controller is configured to identify the network element based on an identity and/or IP address information of the network element received from a network control element upon establishment or modification of the at least one session.

4. The apparatus according to any one of the claims 1 to 3, wherein the controller is configured to monitor a plurality of sessions, and to aggregate resource requirements of all sessions using the network element.

5. The apparatus according to claim 4, wherein the controller is configured to perform the aggregation based on a quality of service class.

6. The apparatus according to claim 3 or 4, wherein the controller is configured to compare the aggregated resource requirements with reference information, and to deduce load condition on the network element and/or a network part based on the comparison.

7. The apparatus according to claim 6, wherein the controller is configured to perform congestion control by applying counter-congestion measures when it is determined that a load on the network element and/or the network part exceeds a threshold set based on the reference information.

8. The apparatus according to any one of claims 1 to 5, wherein the controller is configured to monitor sessions of a group of network elements.

9. The apparatus according to claim 6 or 7, wherein the network part comprises a group of network elements or a part of the network element, and the reference information is set for the network part.

10. An apparatus comprising

a controller configured to manage a plurality of network control elements comprising an apparatus according to any one of the claims 1 to 9.

1 1 . The apparatus according to claim 9, wherein the controller is configured to perform an exchange of congestion information and/or reference information and/or information regarding a threshold set based on the reference information between the network control elements.

12. A method comprising

performing a policy control function,

monitoring at least one session related to a network element, and

performing congestion control based on the at least one monitored session.

13. The method according to claim 12, further comprising

receiving a request for the session, and

binding the session to records related to the network element.

14. The method according to claim 12 or 13, further comprising

identifying the network element based on an identity and/or IP address information of the network element received from a network control element upon establishment or modification of the at least one session.

15. The method according to any one of the claims 12 to 14, further comprising

monitoring a plurality of sessions, and to aggregate resource requirements of all sessions using the network element.

16. The method according to claim 15, further comprising

performing the aggregation based on a quality of service class.

17. The method according to claim 15 or 16, further comprising comparing the aggregated resource requirements with reference information, and deducing load condition on the network element based on the comparison.

18. The method according to claim 17, further comprising

performing congestion control by applying counter-congestion measures when it is determined that a load on the network element and/or a network part exceeds a threshold set based on the reference information.

19. The method according to any one of claims 12 to 16, further comprising

monitoring sessions of a group of network elements.

20. The method according to claim 17 or 18, wherein the network part comprises a group of network elements or a part of the network element, and wherein the reference information is set for the network part.

21 . A method comprising

managing a plurality of network control elements carrying out the method according to any one of the claims 12 to 20.

22. The method according to claim 21 , further comprising

performing an exchange of congestion information and/or reference information and/or information regarding a threshold set based on the reference information between the network control elements.

23. A computer program product comprising code means for performing a method according to any one of claims 12 to 22 when run on a processing means or module.

24. The computer program product according to claim 23, wherein the computer program product is embodied on a computer-readable medium.