T 0015/18 (Coding coefficients generation/CODE ON NETWORK CODING Coduing) of 22.10.2019

Summary of Facts and Submissions

I. This appeal is against the decision of the examining division, posted on 31 July 2017, refusing

European patent application No. 13819210.9. A main request and first, third and fourth auxiliary requests were refused for not fulfilling the requirements of Articles 123(2), 84 and 83 EPC. A second auxiliary request was refused for not fulfilling the requirements of Articles 84 and 83 EPC. A "new main request" and a fifth auxiliary request were not admitted into the examination proceedings under Rule 116 EPC.

During the course of the examination, the examining division also raised novelty and inventive step objections based on

D1: EP 2 264 930 as the closest prior art.

Further, the following document had been cited in the international preliminary report on patentability issued by KIPO on 23 June 2014:

D3: US 2005/0152391.

II. The notice of appeal was received on 4 October 2017 and the appeal fee was paid on the same day. The statement setting out the grounds of appeal was received on

5 December 2017. The appellant requested that the decision be set aside and that a patent be granted based on a main request or a first or second auxiliary request. All requests were submitted with the statement setting out the grounds of appeal. Oral proceedings were requested in the event that none of the three requests were allowed.

III. Claim 1 according to the main request reads as follows:

"A network comprising:

one or more source nodes;

one or more receiver nodes; and

coding nodes, allowing communication of source processes to each receiver node, the coding nodes being connected with input links for communication of input signals to the coding nodes and output links for communication of output signals from the coding nodes,

wherein the output signals from the coding nodes are a linear combination of the input signals,

characterized in that a plurality of said coding nodes are configured to generate coefficients of the linear combination using local node numbers or alternatively local link numbers as inputs to a deterministic mapping from the local node numbers or alternatively from local link numbers to the coefficients of the linear combination,

wherein

the linear combination of processes transmitted from the one or more source nodes present in each signal in the network is specified as a vector of the coefficients, each coefficient corresponding to a process to be transmitted from one or more source nodes, and

wherein said coding nodes are configured to update and to transmit the vector of coefficients by applying to the vector of coefficients linear combinations, wherein the linear combinations applied to the vector of coefficients are the same as the linear combinations applied to data transmitted through the network."

The main request comprises a further independent claim directed to a corresponding method (claim 9).

Due to the outcome of the appeal, there is no need to give details of the claims of the first and second auxiliary requests.

Reasons for the Decision

1. Admissibility of the appeal

The appeal complies with Articles 106 to 108 EPC

(see point II above) and is therefore admissible.

2. Main request

The main request is identical to the second auxiliary request on which the decision under appeal was based and which was refused for lack of clarity (Article 84 EPC) and insufficiency of disclosure (Article 83 EPC).

The board however concurs with the appellant that this request satisfies the requirements of the EPC.

3. Article 123(2) EPC

The board agrees with the decision (see Reasons B3.1) that independent claims 1 and 9 meet the requirements of Article 123(2) EPC.

In that respect, claims 1 and 9 both comprise the features which were considered as essential features by the examining division and which were missing or had been deleted in the independent claims of the then main request and first auxiliary request (see Reasons B1). These features are the features related to the specification, updating and transmission through the network of a vector of the coefficients, disclosed in claim 18 as originally filed.

Moreover, the features related to the use of local node numbers or local link numbers for the generation of the coefficients, which have otherwise not been objected to in the decision, find a clear support in paragraphs [0028] and [0029] of the application as originally filed.

4. Article 84 EPC

The board concurs with the appellant that the wording "deterministic mapping" does not render the subject-matter of the claims unclear, contrary to what is stated in the decision (see B3.2 to B3.4). Mapping is a well-known term having a clear meaning in the technical field of network coding. A mapping in that context is a function that maps elements of a first set of values to elements of a second set of values. Moreover, the skilled person would undoubtedly know that the word "deterministic" is the antonym of "random" or "probabilistic" or "stochastic". Thus, in the context of the application, the skilled person would clearly understand that a deterministic mapping from the local node numbers to the coefficients of the linear combination represents a function, implemented in a coding node, which maps local node numbers (i.e. the node numbers known in the coding node) to the coefficients used by the node for the linear combination, these coefficients being definitely determined from the local node numbers.

Furthermore, the board agrees with the appellant that the feature defining the generation of the coefficients by using a deterministic mapping of the local node numbers, or local link number, to the coefficients is fully supported by the description, in particular paragraphs [0028] and [0029] (see the second sentence in each paragraph).

For these reasons, the board holds that claims 1 and 9 meet the requirements of Article 84 EPC.

5. Article 83 EPC

The board concurs with the appellant that, as mentioned in point 4 above, a deterministic mapping is clearly a deterministic (i.e. non random, non stochastic, non probabilistic) function and that paragraphs [0028] and [0029] of the description provide several workable examples to the skilled person of how to carry out such a function. In particular the skilled person is able to implement the choice of weights a and b as "arbitrary deterministic constant elements from the code alphabet and q is the alphabet size". As argued by the appellant the skilled person would immediately understand that the logical, and sole possible, meaning of this wording is that weights a and b are chosen, i.e. drawn from a set of elements, the code alphabet, in a non-random manner. The skilled person in the field of network coding is obviously able to choose an alphabet of size q, i.e. a mathematical set of q values, to draw weights a and b from this set, and to implement mod q operations in that alphabet.

For these reasons, the board agrees with the appellant that the main request meets the requirements of

Article 83 EPC.

6. Novelty and inventive step

6.1 The decision does not deal with these issues although objections had been raised in previous communications. based on the disclosure of D1.

D1 discloses a network coding scheme based on a centralised code construction where coefficients to be used by each node of the network are first calculated using a known topology of the network and then transmitted to each of the nodes in a control packet and then used for generating the linear combinations of the inputs (see paragraphs [0063], [0086], [0087], Figure 6a, Packet 450 in Figure 4b, Figure 7a, claim 8).

The differences between the subject-matter of claim 1 and the disclosure of D1 are in substance that the coefficients are generated in each node, using a mapping from local node numbers, or local link numbers, and that a vector of coefficients is updated in each node by using the linear combination applied by the node and transmitted by each node through the network.

The technical effect of these differences is that a network coding is possible without the need of a central entity, having knowledge of the established network topology, for generating coding coefficients and distributing them to the nodes. The objective technical problem can thus be formulated as how to perform a network coding which is less resource consuming and less dependent on the network topology.

Starting from D1, the skilled person would not be prompted to change the whole system from a centralised coding scheme to a distributed one. Even if the skilled person were to consider such a change, they would not be able to design without the exercise of inventive skills, the generation of the coefficients at each coding node, based on locally available information such as the local node and link numbers, or the distribution of the necessary decoding information to the receivers through the vector of coefficients, as defined in dependent claims 1 and 9.

Therefore, the board concurs with the appellant that claims 1 and 9 meet the requirements of Article 56 EPC having regard to D1.

6.2 The board has also noted that document D3, assigned to the inventors of the present application and which comprises as Annex 2 the article cited in paragraph [0007], discloses a distributed network coding scheme wherein the coding nodes independently and randomly choose the coefficients for linear combinations from a finite field and wherein a vector of coefficients for each of the source processes is updated and re-transmitted by each node.

The differences between the subject-matter of claim 1 and the disclosure of D3 are thus that the coefficients chosen by each node for its linear combinations are not random but are generated by using a deterministic mapping from local node numbers, or local link numbers to an alphabet of coefficients. The technical effect of these distinguishing features is that the choice of the coefficients may be changed upon time in a deterministic manner, by adapting the mapping. It is plausibly stated in paragraph [0030] that the deterministic mapping at each node can be influenced by feedback from receiver nodes, in order to improve the performance of the network coding, for example in respect of the transmission rates at the receivers. The objective technical problem can thus be formulated as how to optimise the network coding in terms of network performance.

Starting from D3, the skilled person would not be prompted to change the random generation scheme of the coefficients to a deterministic generation scheme. Even if the skilled person were to consider such a change, they would not be able to design, without the exercise of inventive skills, a generation of the coefficients at each coding node, based on locally available information such as the local node and link numbers, as defined in dependent claims 1 and 9.

Moreover, the skilled person would not consider a combination of D3 with D1 due to the fundamental difference between the centralised scheme of D1 and the distributed scheme of D3. Furthermore, even the combination of D3 with D1 would not lead to the subject-matter of claim 1 since the coefficients in D1, although non-randomly chosen, are not based on information locally available to each coding node, namely the local node numbers, or the local link numbers.

6.3 Thus the board holds that claims 1 and 9, and their dependent claims, meet the requirements of

Article 56 EPC, having regard to the prior art on file.

Order

For these reasons it is decided that:

1. The decision under appeal is set aside.

2. The case is remitted to the examining division with the order to grant a patent on the basis of the claims of the main request, filed with the letter of 5 December 2017, and a description and figures to be adapted thereto.