WO2009049676A1

WO2009049676A1 - Method and apparatus for use in a network

Info

Publication number: WO2009049676A1
Application number: PCT/EP2007/061115
Authority: WO
Inventors: Ákos KOVÁCS; István GÓDOR; Sándor RÁCZ; Tamás Borsos
Original assignee: Ericsson Hungary Ltd
Priority date: 2007-10-17
Filing date: 2007-10-17
Publication date: 2009-04-23

Abstract

A method is disclosed of reserving resources in a telecommunications network. A Quality of Experience, QoE, request is received (S2) from a user relating to media content to be delivered to the user over the network. A Quality of Service, QoS, descriptor is determined (S5) in dependence upon the QoE request. The reserving of resources is arranged (S6) in dependence upon the determined QoS descriptor. The QoS descriptor is determined such that its use in the arranging step results in allocated resources sufficient to meet the requested QoE.

Description

METHOD AND APPARATUS FOR USE IN A NETWORK

Technical field

The present invention relates to a method and apparatus for use in a telecommunications network.

Background

In today's telecommunications networks, content providers are faced with new challenges with the introduction of streaming applications. End-users demand constant and high quality for pay services that often cannot be satisfied due to bottleneck links on the transport path. This is typical, especially in access networks, and mostly over wireless channels.

In order to avoid bandwidth-wasting resource reservations for multimedia, and to provide fast and efficient rate adaptation to changing network conditions, scalable video codecs have been developed, like H.264-AVC/SVC [H. Schwarz, D. Marpe, and T. Wiegand, "Combined Scalability Extension of H.264/ AVC", ICIPOS]. Scalable or layered media consists of a base and several enhancement layers each providing quality refinement.

The properties of the scalable media can be communicated to network elements with cross-layer information forwarding methods; see for example references [A. Kovacs and A. Takacs and F. Kalleitner and H. Brand, "Forward Information - A general approach or scalable audiovisual service delivery", ISWCS 2005] and [Takάcs, F. Kalleitner,

"Multimedia Transport Optimization through Forward Information Signalling",

PCT/EP2005/009387, WO 2007/025560, Aug. 2005]. This way, routers along the media transmission path can adapt the media stream to changing network conditions, e.g., in case of congestion. Currently there are two possible ways to reserve bandwidth for multimedia transportation:

(i) Static schemes reserve a fixed amount of bandwidth for the admitted applications. The method can be based on, e.g., the peak rate, but such solutions tend to under-utilize the bandwidth of the network due to Variable Bit Rate (VBR) services.

(ii) Adaptive (dynamic) schemes reserve and update current bandwidth reservations according to implicit or explicit feedback about the network state.

Such feedback can be based on bandwidth estimation methods. Note that bandwidth estimation methods are appropriate also for rate adaptation.

An Adaptive Differentiated Service Multicast Gateway (ADMG) [C-M. Huang, Y.-T. Yu, G.-S. Liau, Statistical flow control mechanism for layered multimedia over the differentiated service network, ACM ICME 2003] can be used to adapt to the network conditions and to compute the approximate values for bandwidth reservation of different service queues based on a layered statistic aggregation model. For cellular networks, an on-line method can be used that adjusts resources adaptively based on existing network conditions.

Another solution is a threshold-based reservation policy [S. Kim, P. K. Varshney, Bandwidth reservation policy for multimedia wireless cellular networks and its analysis, IEEE ICC 2004]. It is a conservative and adaptive QoS framework for provisioning the QoS for both real-time and non-real-time traffic in a multimedia wireless network. The method gradually scales down the bandwidth of ongoing connections to accommodate to changing network conditions.

Another work [S. Manvi, P. Venkataram, Adaptive bandwidth reservation scheme for multimedia traffic using mobile agents, IEEE HSNMC 2002] considers joint problems of adaptive bandwidth reservation and link rearrangement for multimedia traffic under the event of congestion or link failure. The proposed solution is mobile agent based. It proposes to use mobile agents to monitor links and reserve the required resources. They use on-off model for multimedia VBR traffic, and calculate the required bandwidth based on this model.

Summary

According to a first aspect of the present invention there is provided a method of reserving resources in a telecommunications network, comprising: receiving a Quality of Experience, QoE, request from a user relating to media content to be delivered to the user over the network, determining a Quality of Service, QoS, descriptor in dependence upon the QoE request, and arranging for the reserving of resources in dependence upon the determined QoS descriptor, the QoS descriptor being determined such that its use in the arranging step results in allocated resources sufficient to meet the requested QoE.

The method may comprise shaping the traversing media flow based on the reserved resources.

The method may comprise shaping the media flow using cross-layer information forwarding.

The method may comprise determining the size of a buffer used for queue management in shaping the media flow based on the reserved resources.

The method may comprise determining the QoS descriptor from the QoE request in dependence upon application-level information relating to the media content.

The method may comprise receiving the media content information using cross-layer information forwarding.

The media content may comprise layered media content, and the media content information may encapsulate a relationship between a measure of perceived quality and the number of layers received. The method may comprise deriving a mapping between QoE and QoS using the media content information, and determining the QoS descriptor from the QoE request based on the mapping.

The QoE request may comprise an indication of a perceived quality level desired by the user for the media content, at least at a minimum.

The QoE request may comprise an objective measure of a minimum level of perceived quality required by the user for the media content.

The QoS descriptor may be a network level layer descriptor.

The QoS descriptor may comprise a measure of a maximum amount loss allowed to meet the requested QoE.

The method may comprise deriving a measure of quality, for example one expressed as a peak signal-to-noise ratio, from the QoE request, and using the derived measure to determine the QoS descriptor.

The method may comprise performing the receiving and determining steps at a content provider node of the network, with the resources being reserved at a service provider node of the network.

The method may comprise performing the receiving and determining steps at a service provider node of the network, with the resources being reserved at the service provider node.

The service provider node may be a gateway node.

According to a second aspect of the present invention there is provided a method of reserving resources in a telecommunications network, comprising: receiving a Quality of Experience, QoE, request from a user relating to media content to be delivered to the user over the network, and arranging for the reserving of resources in dependence upon the QoE request.

According to a third aspect of the present invention there is provided an apparatus for reserving resources in a telecommunications network, comprising: means for receiving a Quality of Experience, QoE, request from a user relating to media content to be delivered to the user over the network, means for determining a Quality of Service, QoS, descriptor in dependence upon the QoE request, and means for arranging for the reserving of resources in dependence upon the determined QoS descriptor, the QoS descriptor being determined such that its use by the arranging means results in allocated resources sufficient to meet the requested QoE.

According to a fourth aspect of the present invention there is provided an apparatus for reserving resources in a telecommunications network, comprising: means for receiving a Quality of Experience, QoE, request from a user relating to media content to be delivered to the user over the network, and means for arranging for the reserving of resources in dependence upon the QoE request.

The apparatus may comprise means for shaping the traversing media flow based on the reserved resources.

The apparatus may comprise means for determining the size of a buffer used for queue management in shaping the media flow based on the reserved resources.

According to a fifth aspect of the present invention there is provided a gateway node comprising apparatus according to the third or fourth aspect of the present invention.

According to a sixth aspect of the present invention there is provided a program for controlling an apparatus to perform a method according to the first or second aspect of the present invention or which, when loaded into an apparatus, causes the apparatus to become an apparatus according to the third, fourth or fifth aspect of the present invention. The program may be carried on a carrier medium. The carrier medium may be a storage medium. The carrier medium may be a transmission medium.

According to a seventh aspect of the present invention there is provided an apparatus programmed by a program according to the sixth aspect of the present invention.

According to an eighth aspect of the present invention there is provided a storage medium containing a program according to the sixth aspect of the present invention.

An embodiment of the present invention provides a novel static reservation scheme that performs reservation based on the end-user quality of experience (QoE). Since the QoE is strongly related to network level QoS descriptors, such as loss, a direct mapping is proposed between QoE and QoS descriptors, either in the network of the Content Provider or in the network of the Service Provider. An aim is to guarantee a given quality level of the media, with the reservation of the lowest possible amount of resources.

This provides a method to optimize resource reservation if the quality level required by the end-user is known. An embodiment of the present invention utilizes network bandwidth in an efficient way and takes into account not only network characteristics but also the user-perceived quality.

One or more of the following advantages are provided by use of an embodiment of the present invention:

• A static reservation method is provided that has low complexity compared to dynamic methods. That is, no signalling is required during the session. The system can perform "a priori" reservation.

• It can be used both for unicast and multicast media delivery. Considering multicast, the described network scenario can be extended easily. Reservation can be performed only on those branches of the multicast tree to which previously no receivers were connected. • Reservation is based on user perceived quality, which is the most important QoS descriptor that matters for the client.

• The experienced quality and the network characteristics are optimised at the same time.

Brief description of the drawings

Figure 1 schematically illustrates a system in which an embodiment of the present invention operates;

Figure 2 illustrates a mapping performed in an embodiment of the present invention;

Figure 3 schematically illustrates an example network architecture in a first scenario to illustrate an embodiment of the present invention;

Figure 4 schematically illustrates an example network architecture in a second scenario to illustrate an embodiment of the present invention;

Figure 5 is a block diagram schematically illustrating one possible implementation of a node that performs a reservation process in an embodiment of the present invention;

Figure 6 is a schematic illustration of steps performed in an embodiment of the present invention; and

Figure 7 is a schematic block diagram illustrating parts of a computation node for performing steps shown in Figure 6.

Detailed description

Although media stream adaptation using cross-layer information as described above can scale down the stream to meet altered conditions, it cannot guarantee a certain Quality of Service (QoS) for the end-user. Adaptation methods for layered media provide graceful quality degradation, but cannot guarantee a minimum quality level that may be requested by the receiver of a pay service.

Bandwidth reservation can solve this problem to some degree. Reserving a certain amount of bandwidth does not allow the quality of the media stream to fall below a certain level. However, resource reservation raises a difficult question as to how much bandwidth to reserve, and through which mechanism.

Both the dynamic and static methods mentioned previously consider only network level characteristics, based on which the reservation of resources is performed. These characteristics include, for example: loss, delay and jitter.

Though such characteristics describe the behaviour of the stream reasonably at a network level, where the reservation is actually carried out, they do not consider the end-user perceived Quality of Experience (QoE). Since the reservation is usually done by network operators, it is possible that the requirements of the end-user are neglected, and instead the operators' preferences dominate the decisions made.

Current methods tend to start the streaming session by providing a lower grade of QoS for the client to keep the startup (session setup) delay low. Later, during streaming, they refine the Quality if the condition of the network allows.

Static schemes concentrate on providing the required network level characteristics for the streaming application. That is, these schemes make reservation based on the network level descriptors mentioned above, while they do not consider the affect of such descriptors on the end-user perceived quality.

Generally, static schemes have low complexity, the reservation is done prior to the start of the media transmission, but cannot estimate well the required resources to be reserved. That is why such schemes reserve for peak or mean bitrate, however, the former can be bandwidth wasting while the latter may not provide satisfactory perceived quality (it is possible that the peak rate of a VBR stream is a triple of the mean data rate).

Though dynamic schemes allow the network to adjust the reserved amount of bandwidth in time to the changing resource requirements of the media flow, these methods also do not consider the end-user quality experience. Taking into account, consideration of perceived quality by dynamic schemes would hardly be feasible, since it would need rapid and almost continuous translation of QoE descriptors to network level characteristics such as loss, for example.

An embodiment of the present invention provides a static reservation scheme that takes into account not only network characteristics but also the user-perceived quality, or QoE, thus providing a minimum level of end-user experience according to the receiver's preference.

As described in further detail below, a method according to an embodiment of the present invention reserves the appropriate amount of bandwidth that required by the media flow to provide the requested level of end-user quality of experience (QoE), and shapes the incoming media flow at the edge of a given network domain in which the reservation is valid. The shaping is done, for example, by buffering. This guarantees a pre-defined delay constraint for the flow that is set by the operator. The installed buffer may also be used for the adaptation of the media flow if the network offers free capacity over the reserved capacity.

We assume that the quality curve of the given media is available. For layered media, the quality can be measured as the function of the number of received layers. The quality curve can be derived from the so-called rate distortion curve. The higher amount of data that is available for the decoder, the lower the distortion is. In this regard, the quality curve describes theoretically or empirically a media flow and is its characteristics. The system model considered here is a network scenario, in which a scalable stream traverses a bottleneck link. Before the bottleneck link, a queue is installed that shapes the traversing media flow (performed e.g. by Active Queue Management, AQM) based on the forwarded cross-layer information. That is, in this model it is assumed that application-layer information is available at the queue.

The shaping does not allow the media stream to exceed the defined bandwidth constraints (based on the end-user demand on perceived quality and based on admission control mechanism) and the resource reservation does not allow the quality of the media stream to fall below the defined level of quality (demanded by the end-user). The bottleneck link(s) is assumed to be anywhere inside the network of a service provider.

That is, the aim of the service provider is to guarantee a given quality level for the media, with the reservation of the lowest possible amount of resources. If the multimedia stream is buffered with a feasible delay constraint of real-time services, and the appropriate amount of bandwidth is reserved for the session, the required user- perceived quality can be guaranteed.

The reservation method uses the QoE demand of the end-user and the quality curve of the media as input. Based on the QoE demand of the end-user, the requested quality level is translated (mapped) to a network level QoS descriptor, such as the loss. This mapping gives the maximum amount of loss that is allowed to reach the requested level of perceived quality. It can be computed (by the Computation Method, CM) what buffer size (used by the AQM) and link capacity meets the loss constraint.

Figure 1 shows the participants of an example reservation process, which are a Content Provider 10, a Service Provider 20, and an End User 30. Figure 1 also shows where the CM and the mapping of QoE to QoS can be performed. It also shows the information flow within the reservation procedure.

Solid and dashed lines in Figure 1 differentiate between two main possible alternatives of a reservation procedure embodying the present invention. In the first case, indicated by solid lines, the CM is run by the Content Provider 10. In the second case, indicated by dashed lines in Figure 1, the Service Provider 20 runs the CM. These two cases will be discussed in more depth further below, after a generalised description of the operation of an embodiment of the present invention with reference to Figures 6 and 7.

Figure 6 is a schematic illustration of steps performed in an embodiment of the present invention, separated into steps performed at each of the Content Provider 10, Service Provider 20, and End User 30. Shown separately in Figure 1 are the CM steps performed at a Computation Function 50 of the network, which can either be located at the Content Provider 10, or at the Service Provider 20, or elsewhere in the network. Figure 7 is a schematic block diagram illustrating parts of the Computation Node 50 of Figure 6. If the Computation Function 50 is part of or associated with one of the other nodes shown in Figure 6, then an illustrated step showing communication between the Computation Function 50 and that other node can be considered to be an internal communication, or that step can be ignored. This applies likewise to the corresponding parts in Figure 7.

In step Sl, the End User 30 sends a QoE Request to the Computation Function 50, which is received at a first Receiving Portion 52 of the Computation Function 50 in step S2. The QoE Request comprises an objective measure of a minimum level of perceived quality required by the End User 30 for media content subsequently to be received. In step S3, media information relating to the media content is sent from the Content Provider 10 to the Computation Function 50, which is received at a second Receiving Portion 54 of the Computation Function 50 in step S4. This media information is used by a BW Calculating Portion 55 of the Computation Function 50 in step S5, together with the QoE Request received in step S2, to calculate the bandwidth requirements to meet the QoE Request. In step S6, a Resource Reservation Arranging Portion 56 of the Computation Function 50 arranges for the reservation of bandwidth according to the requirements calculated in step S5, by signalling those requirements to the Service Provider 20. In step S7 the bandwidth requirements are received at the Service Provider 20, and in step S8 the appropriate bandwidth is reserved. These various steps are discussed in more detail below. Referring again to Figure 1, in the first case mentioned above, as indicated by solid lines in Figure 1, the CM is run by the Content Provider 10. The Content Provider 10 is responsible for distributing the media content to the subscribers, i.e., to the end-users (receivers) 30.

Since the Content Provider 10 is aware locally of the media information required for the QoE-to-QoS mapping and for the CM, no cross-layer communication is needed in the network. The input of the mapping is the requested end-user QoE and the media information. The content provider performs the descriptor mapping by the CM, and signals the Required Bandwidth to the appropriate node that initiates the reservation itself. Typically this node is inside the transport network of the Service Provider, and is typically its ingress node.

In the second case, indicated by dashed lines in Figure 1, the Service Provider 20 runs the CM in an appropriate node (typically an ingress node of its transport network) and initiates the reservation process (based on the derived QoS descriptor from the mapping). The media information is signalled by cross-layer information forwarding techniques to this dedicated node (see reference [Takάcs, F. Kalleitner, "Multimedia Transport Optimization through Forward Information Signalling", PCT/EP2005/009387, WO 2007/025560, Aug. 2005]) as well as the target user- perceived quality (QoE).

The end-user QoE is a quantitative value that objectively reflects the perceived quality. This QoE level is an input of the bandwidth calculation process and is signalled by the receiver to the appropriate network entity that runs the CM.

The application-level characteristics of the media (media information), also an input of the computation process, comprise the quality curve. For example, these characteristics relate a measure of perceived quality to the number of layers received. The quality curve relates the experienced quality, for example expressed as a peak signal-to-noise ratio (PSNR), in terms of the received amount of data. For example, in the case of scalable/layered bitstreams, if the maximum quality is 50 dB and the media has 10 layers, and assuming for simplicity that the curve is linear, the base layer would provide 5 dB, the base layer plus the first enhancement layer would provide 10 dB, the lowest three layers would provide 15 dB, and so on.

In turn, the correctly received number of layers is related to the actual loss ratio. For example, if there is no loss, all layers are received, and if the loss is high it is possible that only the base layer is received. For each case, the perceived quality can be determined. This allows a mapping between quality and loss, such a mapping being described further below with reference to Figure 2.

It is assumed that such properties of the media are available for the edge node of the domain in which the reservation is performed. This application-level information can be communicated to the appropriate nodes by, e.g., cross-layer information forwarding techniques such as proposed in reference [Takάcs, F. Kalleitner, "Multimedia Transport Optimization through Forward Information Signalling", PCT/EP2005/009387, WO 2007/025560, Aug. 2005]. Note that if the reservation is initiated by the media sender, such signalling is not needed.

At the IP level, one way to adapt the bitstream to altered network conditions is to drop less significant packets in times of congestion. Scalable Video Codecs (SVCs) like H.264/SVC generate a scalable bitstream that is suitable for this kind of adaptation. In the description that follows, a possible realization of an Active Queue Management (AQM) scheme is introduced to handle temporary congestion by packet-discarding, the Cross-layer AQM (XAQM).

The importance of the media frames can be made available at the IP level as priorities. Such information can be provided, for example, through cross-layer information forwarding as described for example in reference [Takάcs, F. Kalleitner, "Multimedia Transport Optimization through Forward Information Signalling", PCT/EP2005/009387, WO 2007/025560, Aug. 2005]. The priority of the packet can be encoded in the DiffServ Code Point (DSCP), or alternatively in the packet payload. Based on this priority information, the XAQM can decide what to do with a received packet.

Consider a media stream consisting of three layers: a base layer and two enhancement layers. The base layer has the highest priority, while the second enhancement layer has the lowest priority. A basic rule of the XAQM is that a higher priority packet can push out a packet with lower priority. If there is not enough space for the new packet, the

XAQM starts to scan the packets in the queue. The scanning is started with the lowest priority and the size of the packets of each priority is calculated. If it is possible to free enough buffer capacity for the new packet, then the XAQM drops the lower priority packets. If it is not possible to free the needed buffer size, the XAQM simply drops the arriving packet.

An illustration of the mapping of parameters, and how the required bandwidth is computed, is shown in Figure 2. For an example relating to the display of video, the end user might be able to choose from a pre-defined set of media quality levels based on a SLA, for example low, medium and high resolution (the QoE in this case relates to the visible video quality experienced by the human eye). The end user's choice of quality is signalled to the node (e.g. the media gateway) that performs the mapping and initiates the reservation process, and the user request is translated to a quantitative value like the peak signal-to-noise ratio (PSNR).

The QoE request, re-expressed as a PSNR, is then mapped (step 1 of Figure 2) to a network level QoS descriptor (measure) of a data stream/flow, for example loss delay and so on. In this case, the mapping is to an amount of loss that is acceptable for the decoder to provide the required level of quality. This amount of loss can then be mapped (step 2 of Figure 2) to the loss curve that is generated by the Computation Method (CM). Thus the appropriate amount of bandwidth can be reserved to provide the required quality (step 3 of Figure 2).

The reservation process itself is a further step. An ingress node of the domain in which the reservation is to be applied first installs the AQM buffer for the incoming media flow. Second, the ingress node initiates a procedure to reserve the required resources. The reservation process can be performed by, for example, either Resource ReSerVation Protocol (RSVP) or Next Steps in Signalling (NSIS) according to whether multicast or unicast transmission is used.

In the proposed reservation scheme, two main scenarios can be considered depending on where the CM is performed, and these are described below. In both scenarios the bottleneck is assumed to be anywhere inside the service provider's transport network, and the reservation is therefore assumed to be performed there.

The first scenario will now be described with reference to Figure 3.

In this scenario, the CM is performed by the content provider 10. In step (1) the content provider 10 receives the desired user-perceived quality (QoE) from the end-user and access the locally available media information.

In step (2) the CM computes the requested bandwidth required for the requested QoE. Based on the results of the CM, in step (3) the content provider 10 signals the bandwidth request to the service provider's edge node (Gateway) 22. The signalling can be performed by, e.g., RSVP or NSIS.

In step (4) the service provider 20 reserves the requested bandwidth for its transport network (Transport) 24, in between the Gateway 22 and an Access Node 26, in order to guarantee the QoE that is requested by the end-user.

It is also possible to check, by any appropriate admission control mechanism, whether there is enough free capacity for the new stream. If there is not, the service provider 20 notifies the content provider 10 about the reservation failure, rejecting the reservation, foe example by the appropriate messages that are used for such purpose in RSVP or NSIS. In this case, the end-user would possibly select a lower level of QoE and start the negotiation again. The second scenario will now be described with reference to Figure 4.

In this scenario, the CM is performed by the service provider 20. Typically, the reservation can be edge-to-edge in between the ingress (Gateway) 22 and the outgress (Access Node) 26 nodes of the service provider's transport network 24. In step (1), the required media information (quality curve) is signalled by cross-layer information forwarding methods, e.g., such as described in reference [Takάcs, F. Kalleitner, "Multimedia Transport Optimization through Forward Information Signalling", PCT/EP2005/009387, WO 2007/025560, Aug. 2005], to the indicated node (Gateway) 22 of the Transport (Service Provider's) network 24. Such information can be forwarded by existing resource reservation protocols like RSVP or NSIS. Also in step (1), the target user-perceived quality, the requested QoE, is signalled to the indicated node (Gateway) 22.

In step (2), the indicated node (Gateway) 22 performs the CM and initiates and completes the reservation process in step (3). As for the first scenario, if the requested bandwidth cannot be reserved due to lack of capacity, a negotiation process can start.

It is also possible that the reservation is valid in an end-to-end context, where end-to- end can be, e.g. between the content provider 10 and the transport/access network's Access Node 26. For this case, the first scenario described above is valid; that is the content provider 10 performs the CM. However, the reservation would be initiated by any of the edge nodes of the overprovisioned network (at the content provider's side) instead of the ingress node (Gateway) 22 of the service provider's transport network 24.

In the case of a multicast scenario, the reservations for the same stream can be aggregated, and transmitted through a common delivery path towards the receivers, i.e., through the multicast tree. It is also possible that the service provider 20 uses more than one edge node for the reservation method. In this case, neither of the ingress nodes would be aware of the complete capacity offers of the network. That is, bandwidth broker functionality can be applied that overtakes the call admission control of the edge nodes. Another opportunity can be a distributed solution where via e.g., RSVP, each node can decide whether to forward or decline the reservation request.

In case of multicast, it is also possible to reserve end-to-end in the context it is described above. However, if e.g., PIM-SM [B. Fenner et al, "Protocol Independent Multicast - Sparse Mode (PIM-SM): Protocol specification," RFC 4601, Aug. 2006.] is used for multicast routing, the initiator node in the core network is typically the Rendezvous Point, which is the root of the multicast tree.

One possible embodiment of a node that performs the reservation process is shown schematically in Figure 5. In this embodiment, the illustrated node 220 performs the CM and also initiates the reservation. The selected node 220 communicates with the end-user and a Call Admission Control (CAC) entity. The CAC entity has a global knowledge on available capacity within the network. The proposed method is detailed in the following steps as marked in Figure 5.

In step (1) the required cross-layer information and in step (2) the target end-user quality is signalled to the node 220. In step (3), a Bandwidth Estimator 222 of the node 220 uses the Computation Method, CM, to compute the required bandwidth, and signals this to a Local Admission Controller (LAC) 224 of the node 220.

The LAC 224 determines whether the network has capacity for the incoming flow with the requested bandwidth meeting the target perceived quality. The decision is based on the available bandwidth information, received in step (4) from the CAC entity.

If the new media flow can be admitted with the requested bandwidth characteristic, the LAC 224 informs the end-user with a positive acknowledgement in step (5), reserves the required capacity in step (6a), directly or via the CAC entity, sets the appropriate buffer size in step (7), and starts forwarding the media stream from the Input Interface (IIF) 226 to the Output Interface (OIF) 228 corresponds the path toward the receiver. On the other hand, if the media flow cannot be admitted at the requested target quality, the LAC 224 starts a negotiation period with the end-user. The LAC 224 sends a negative acknowledgement regarding the recent target quality in step (5), and indicates in step (6b) to the Bandwidth Estimator to perform a new computation for the new target quality received again in step (2).

In the example described above with reference to Figure 5, the illustrated node performs the CM and also initiates the reservation. If the content provider instead performs the CM, the Bandwidth Estimator would not be required. The requested amount of bandwidth would be signalled according to the reservation protocol used.

It is noted that, in general, media information can comprise more than just the quality curve. The quality curve could be only a subset of the media information; however, for the purposes of resource reservation in an embodiment of the present invention, only the quality curve would normally be required. The media information is cross-layer information for the network layer, and comes from the application layer, or more precisely from the codec at the content provider. It is distributed throughout the network and each point in the network utilizes the specific information that it needs. Besides the quality curve, there is other information that e.g. tells the network what media frame should be protected more and what media frame should be protected less, and so on.

It will be appreciated that operation of one or more of the above-described components can be controlled by a program operating on the device or apparatus. Such an operating program can be stored on a computer-readable medium, or could, for example, be embodied in a signal such as a downloadable data signal provided from an Internet website. The appended claims are to be interpreted as covering an operating program by itself, or as a record on a carrier, or as a signal, or in any other form.

It will also be appreciated by the person of skill in the art that various modifications may be made to the above-described embodiments without departing from the scope of the present invention as defined by the appended claims. It will also be appreciated that, where it is stated that a message or signal is sent to a remote node, it is not to be implied that the message or signal is sent directly to the remote node; it can be that the message or signal is eventually received at the remote node via another node or nodes.

Claims

1. A method of reserving resources in a telecommunications network, comprising: receiving a Quality of Experience, QoE, request from a user relating to media content to be delivered to the user over the network, determining a Quality of Service, QoS, descriptor in dependence upon the QoE request, and arranging for the reserving of resources in dependence upon the determined QoS descriptor, the QoS descriptor being determined such that its use in the arranging step results in allocated resources sufficient to meet the requested QoE.

2. A method as claimed in claim 1, comprising shaping the traversing media flow based on the reserved resources.

3. A method as claimed in claim 2, comprising shaping the media flow using cross-layer information forwarding.

4. A method as claimed in claim 2 or 3, comprising determining the size of a buffer used for queue management in shaping the media flow based on the reserved resources.

5. A method as claimed in any preceding claim, comprising determining the QoS descriptor from the QoE request in dependence upon application-level information relating to the media content.

6. A method as claimed in claim 5, comprising receiving the media content information using cross-layer information forwarding.

7. A method as claimed in claim 5 or 6, wherein the media content comprises layered media content, and wherein the media content information encapsulates a relationship between a measure of perceived quality and the number of layers received.

8. A method as claimed in claim 5, 6 or 7, comprising deriving a mapping between QoE and QoS using the media content information, and determining the QoS descriptor from the QoE request based on the mapping.

9. A method as claimed in any preceding claim, wherein the QoE request comprises an indication of a perceived quality level desired by the user for the media content, at least at a minimum.

10. A method as claimed in any preceding claim, wherein the QoE request comprises an objective measure of a minimum level of perceived quality required by the user for the media content.

11. A method as claimed in any preceding claim, wherein the QoS descriptor is a network level layer descriptor.

12. A method as claimed in any preceding claim, wherein the QoS descriptor comprises a measure of a maximum amount loss allowed to meet the requested QoE.

13. A method as claimed in any preceding claim, comprising deriving a measure of quality, for example one expressed as a peak signal-to-noise ratio, from the QoE request, and using the derived measure to determine the QoS descriptor.

14. A method as claimed in any preceding claim, comprising performing the receiving and determining steps at a content provider node of the network, with the resources being reserved at a service provider node of the network.

15. A method as claimed in any one of claims 1 to 12, comprising performing the receiving and determining steps at a service provider node of the network, with the resources being reserved at the service provider node.

16. A method as claimed in claim 14 or 15, wherein the service provider node is a gateway node.

17. A method of reserving resources in a telecommunications network, comprising: receiving a Quality of Experience, QoE, request from a user relating to media content to be delivered to the user over the network, and arranging for the reserving of resources in dependence upon the QoE request.

18. An apparatus for reserving resources in a telecommunications network, comprising: means for receiving a Quality of Experience, QoE, request from a user relating to media content to be delivered to the user over the network, means for determining a Quality of Service, QoS, descriptor in dependence upon the QoE request, and means for arranging for the reserving of resources in dependence upon the determined QoS descriptor, the QoS descriptor being determined such that its use by the arranging means results in allocated resources sufficient to meet the requested QoE.

19. An apparatus for reserving resources in a telecommunications network, comprising: means for receiving a Quality of Experience, QoE, request from a user relating to media content to be delivered to the user over the network, and means for arranging for the reserving of resources in dependence upon the QoE request.

20. An apparatus as claimed in claim 18 or 19, comprising means for shaping the traversing media flow based on the reserved resources.

21. An apparatus as claimed in claim 18, 19 or 20, comprising means for determining the size of a buffer used for queue management in shaping the media flow based on the reserved resources.

22. A gateway node comprising apparatus as claimed in any one of claims 18 to 21.

23. A program for controlling an apparatus to perform a method as claimed in any one of claims 1 to 17.

24. A program which, when loaded into an apparatus, causes the apparatus to become an apparatus as claimed in claim 18 to 22.

25. A program as claimed in claim 23 or 24, carried on a carrier medium.

26. A program as claimed in claim 25, wherein the carrier medium is a storage medium.

27. A program as claimed in claim 25, wherein the carrier medium is a transmission medium.

28. An apparatus programmed by a program as claimed in any one of claims 23 to

27.

29. A storage medium containing a program as claimed in any one of claims 23 to 26.