T 1228/08 – A Step Back

This is an examination appeal.

Independent claims 1 and 9 before the Board read:

1. Apparatus for processing a signal comprising:

a coder (203) for generating at least first and second representations of the signal, the at least first and second representations being different from each other and being deliverable at rates lower than or equal to the required delivery rate of the signal; and

a controller (280, 285) for packaging at least one of the at least first and second representations into a plurality of packets (411, 413) for communication through a packet-switched network, the resulting packet-stream comprising either just packets derived from the first representation or packets derived from the first representation in combination with packets derived from at least one of the other representations depending at least in part on the connection speed associated with the connection (125) over which the packet stream is to be delivered to a given client terminal (130), each packet including at least an indicator and an information content derived from one of the at least first and second representations, the indicator identifying the representation from which the information content is derived, whereby the information content of a packet stream based on the first representation alone is such that the signal recovered therefrom affords the minimum acceptable signal quality.

9. A method for processing a signal comprising

generating at least first and second representations of the signal, the at least first and second representations being different from each other and being deliverable at rates lower than or equal to the required delivery rate of the signal; and

packaging (280, 285) at least one of the at least first and second representations into a plurality of packets (411, 413) for communication through a packet-switched network, the resulting packet-stream comprising either just packets derived from the first representation or packets derived from the first representation in combination with packets derived from at least one of the other representations depending at least in part on the connection speed associated with the connection (125) over which the packet stream is to be delivered to a given client terminal (130), each packet including at least an indicator and an information content derived from one of the at least first and second representations, the indicator identifying the representation from which the information content is derived, whereby the information content of a packet stream based on the first representation alone is such that the signal recovered therefrom affords the minimum acceptable signal quality.

In what follows the Board deals with the question whether document D1 was the right starting point for the inventive step assessment:

[3.2.1] Document D1 discloses a multicast audio tool which uses hierarchical coding. The audio signal to be transmitted is sampled with 16 bits per sample. Each sample is divided into four groups consisting of four bits each. The groups are sent as separate data streams to the destination where they are re-assembled for playback. The data source will always send all four groups but, depending on the receiver’s preferences, some of these groups may not be forwarded to the destination by the local multicast router. The more groups which are received at the destination, the higher the resolution of the re-assembled signal. One factor which is taken into account in the forwarding of groups from the multicast router to the destination is the available bandwidth.

[3.2.2] The method of claim 9 is distinguished from the teaching of D1 in that the packaging of the signal for transmission is performed in dependence on the available connection speed. In D1, all data is packaged and sent irrespective of the connection speed; the local multicast router then controls the forwarding of the packets based on the connection speed but does not influence the packaging itself.

Moreover, the representations which are sent in the method of claim 9 (which correspond to the “groups” in D1) are packaged together as a single data stream and are not sent as separate streams as in D1.

[3.2.3] In the contested decision, the examining division (ED) argued that in cases in which only a single client was expected to access a single file at any one time, the skilled person would see that the multicasting properties of the system of D1 were not required and that the local multicast router would be superfluous. In such cases, it would be obvious to transfer the task of selecting which groups to forward to the client to the server itself, allowing the server to package the data to be transmitted into a single stream. The music-on-demand service described on page 1, line 31 to page 2, line 17 of the present application as filed was cited to show that it was known to send a given version of a musical piece as a single data stream. To transmit just one stream was considered by the ED to be a technological step back from the multicasting system of D1 and therefore not inventive. In other words, it would have been obvious to adapt the multicast system of D1 to provide a system in which data is directly transmitted in a single steam from the server to the destination without the intervention of a multicast router.

[3.2.4] In the statement setting out the grounds of appeal, the appellant argued that if the multicasting properties of the system of D1 were not required then the system of D1 represented the wrong starting point for the assessment of inventive step. The question of how to adapt the system of D1 for use in data transmission when only one client would ever require access to the data would simply not arise because the skilled person would only consider using the system of D1 for multicasting. Thus, to suggest that D1 can be modified to dispose of the multicast router and to package the groups into a single data stream for direct transmission to the receiver was pure hindsight.

[3.2.5] The Board agrees with the appellant’s position. Although D1 discloses the use of hierarchical coding, which is indeed a major aspect of the present invention, the Board considers that this document does not represent a realistic starting point for an attack on inventive step. Following T 439/92, a conscious choice of starting point not only determines the subject-matter serving as a starting point but also defines the framework for further development (see Case Law, I.D.3.5, third paragraph). Thus, using D1 as a starting point would mean that any further development would be carried out in the context of multicasting: it is unrealistic to suggest that, starting from this disclosure, the skilled person would go outside this framework – indeed take a technical step back, as observed by the ED – to develop a non-multicasting system.

Furthermore, as the appellant has pointed out, the packet streams which are constructed in D1 are independent of the connection speed. All of the four-bit groups in D1 are sent individually to the multicast router which then forwards specific groups – again individually – to the receiver. This is what gives the multicast system of D1 the prerequisite flexibility: separate groups are sent in separate data streams so that at the router, individual groups may be selected for forwarding to the destination. To send a single data stream from the data source would be to lose the ability to select certain data building blocks at the router and to consequently lose the ability to adapt the data transmission to changing network conditions. In view of the fact that the whole idea in D1 is to allow maximum flexibility with regard to the data packets which are retrieved by the user, the Board is of the view that it would be counter-intuitive to provide a single stream in D1.

[3.2.6] For these reasons, the Board is of the opinion that the method of claim 9, and correspondingly also the apparatus of claim 1, cannot be derived in an obvious manner when starting from the disclosure of document D1.

The Board found the claims to be inventive over the prior art described in the application.

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