T 0522/21 (Modulation signalling in HSDPA/NOKIA) 05-07-2023

Reasons for the Decision

1. Admissibility of the appeals

The appeals of PP, O1 and O3 comply with the provisions of Articles 106 to 108 EPC (see points II to IV above) and are therefore admissible.

2. Admissibility of the interventions

The interventions of O5, O6, O7 and O8 comply with the provisions of Article 105 EPC (see points VI, VII, XIII and XIV above) and are therefore admissible.

3. The numbering of documents stated in the Summary of Facts and Submissions of the impugned decision (point VI) is used in the following.

4. Admission of the main request

At the oral proceedings, O4 requested that PP's main request on file - to maintain the patent according to the main request considered in the decision, as filed with PP's letter of 21 June 2023 - not be admitted into the appeal proceedings. O4 argued that, although this request had been filed with PP's notice of appeal, it had been subsequently clearly replaced by the request to maintain the patent as granted in PP's statement setting out the grounds of appeal. O4 pointed to

T 1695/14 and argued that, in the case in hand, the request in the statement setting out the grounds of appeal did not have to be interpreted since it was clearly formulated (see section "A. Requests" of the statement). According to O4, the main request in this case should thus be considered to have been filed after the summons to oral proceedings and should not be admitted under Article 13(2) RPBA. O1, O5, O6, O7 and O8 also requested at the oral proceedings that PP's main request not be admitted.

However, the board notes that the differences between the claims of the main request on which the decision is based and the claims as granted are that dependent claims 3 to 6 and 9 to 11 as granted have been deleted and the other claims have been renumbered. The board agrees with PP that the substantial submissions in its statement setting out the grounds of appeal deal with independent claims 1 and 3 of the main request on which the decision is based, which are identical to independent claims 1 and 7 as granted; see section B.1. None of the submissions deal with the deleted dependent claims 3 to 6 and 9 to 11 as granted. Moreover, section E.26 of the statement setting out the grounds of appeal mentions that the decision found there was an inconsistency between the claims of the main request and paragraphs [0030] and [0031] of the description since these paragraphs corresponded to claims of the granted patent which had been deleted. Thus, said section clearly states that the main request is the main request on which the decision is based.

The board also notes that none of the opponents or parties addressed this issue in their written submissions in the appeal proceedings.

For these reasons, the board held at the oral proceedings that it was clear from PP's statement setting out the grounds of appeal that the main request was the main request on which the decision was based, and that this request had not been amended in PP's further submissions. The board thus decided at the oral proceedings to admit PP's main request under the provisions of Article 12(2) RPBA.

5. Non-enabling disclosure of the priority document D14

5.1 With its notice of intervention, O8 raised the objection that the priority claim based on D14 was not valid since D14 was not an enabling disclosure. As stated by O8, it is established case law that a valid priority claim can only be made when the disclosure in the priority document is an enabling disclosure for a skilled person (see Case Law of the Boards of Appeal, 10th edition, Part II.D.3.1.6). PP rightfully argued that the requirements with respect to enabling disclosure of the priority application, i.e. the requirements for compliance with Article 83 EPC, were that the skilled person could implement the invention without undue burden, on the basis of the disclosure of the priority document and the skilled person's common general knowledge.

Claim 1 according to the main request and auxiliary requests 1 and 2 in substance specifies that, if both a user equipment and a serving cell support 64QAM, and if a modulation indication bit indicates quadrature amplitude modulation, only 6 bits of the

7 channelization code-set information bits in the

HS-SCCH part 1 structure, as defined in the 3GPP Release 5 specification, are interpreted as code-set information.

In the 3GPP TS 25.212 specification for HSDPA, annexed to D14 as D14c, 7 channelization code-set information bits are defined as indicating to the user terminal which code out of the 15 possible HS-PDSCH codes is the first code used and how many consecutive codes following this first one are used (see paragraph [0035] of the patent). The number of consecutive codes used (P, integer between 1 and 15) and the number of the starting code (O, integer between 1 and 15) are encoded using the 7 bits xccs,1 to xccs,7 of the channelization code-set information using the unsigned representation of integers calculated by the following expressions given in section 4.6.2.3 of D14c:

xccs,1, xccs,2, xccs,3 = min(P-1,15-P) (code group indicator),

and

xccs,4, xccs,5, xccs,6, xccs,7 = |O-1-|_P/8_|*15|, where |_ _| is the floor bracket symbol (code offset indicator).

To be able to implement the claimed invention, the skilled person thus needs to find in the priority document D14 at least one embodiment that makes it possible to code a code group indicator and a code offset indicator on 6 bits only instead of 7 bits, as defined by claim 1 in the case where 64QAM is supported and signalled by one bit of the 7 channelization code-set bits. In that respect, the board agrees with O8 that the almost literal support of claim 1 by D14 (from page 6, last paragraph to page 7, first paragraph) is not a sufficient disclosure to put the invention defined by claim 1 into practice.

PP argued that D14 disclosed at least two embodiments which enabled the skilled person to carry out the invention.

5.2 First embodiment

5.2.1 D14 presents a first embodiment on page 9, in which the first three bits of the channelization code-set information xccs,1, xccs,2, xccs,3 code the group indicator in a manner identical to the 3GPP Release 5 specification, and the next three bits code the code offset indicator by the formula:

xccs,4, xccs,5, xccs,6 = |O-1- P/8 *15|/2, with the interpretation of the start code O being modified to be an odd integer between 1 and 15.

However, as correctly pointed out by O8 and acknowledged by PP, this last formula does not lead to a correct implementation since it may deliver decimal numbers which cannot be signalled with a binary code. O8 showed that, if P = 5 and O = 11, the result of the formula is 0.3215, which cannot be represented by a 3-bit binary code. The board also found several combinations of (P, O) for which the formula delivers a decimal number. As a consequence, the formula disclosed on page 9 of D14 does not allow the skilled person to code the last 3 bits of the channelization code-set information.

Moreover, as argued by O8, even if the formula on page 9 of D14 were corrected to read |O-1-|_P/8_|*15|/2, the formula would not enable parameters O and P to be signalled using the 6 bits of the channelization code-set information. In that respect, O8 pointed to the example (P, O) = (11, 5), which leads to a decimal number as result of the formula, which cannot be represented by the 3 signalling bits xccs,4, xccs,5, xccs,6.

Furthermore, as argued by O8, even if the floor brackets were introduced in the formula giving

xccs,4, xccs,5, xccs,6 and its result were truncated to a binary number, the signalling of P and O to the user equipment using the channelization code-set information xccs,1, xccs,2, xccs,3, xccs,4, xccs,5, xccs,6

would be the same for different pairs (P, O), e.g. the pairs (11, 5) and (5, 11). Thus, an additional bit would be needed to distinguish some pairs (P, O) from each other, so signalling with 6 bits, as defined by claim 1, cannot be implemented.

5.2.2 With respect to this first embodiment disclosed on page 9 of D14, PP argued that the skilled person would identify the error in the formula giving

xccs,4, xccs,5, xccs,6 and that the correction was obvious for them. According to PP, the skilled person would immediately have realised that this formula was a refinement of the formula of the specification annexed to D14 as Annex C (see D14c), adapted with a division by 2 to the case where O is an odd number between 1 and 15, i.e. O may take 8 values. In addition, the skilled person would also have recognised, by comparing the formulas on pages 8 and 9 of D14, which give the code offset indicator, with the formula in section 4.6.2.3 of the specification D14c, that the absence of floor brackets rounding the term "P/8" down to the lower integer in both formulas was an accidental omission due to an unintended typographical error. PP further argued that the skilled person would also recognise that the formula on page 9 of D14 giving xccs,4, xccs,5, xccs,6

omitted floor brackets around the whole mathematical expression, i.e. xccs,4, xccs,5, xccs,6 =

|_|O-1-|_P/8_|*15|/2_|, because it was explicitly disclosed that the equation had to result in an "unsigned binary representation of integers" fitting into 3 bits.

The board is not convinced by this line of argument and agrees with O8 that, for the skilled person, the formula on page 9 of D14 should be different from the formula on page 8 since it relates to a modification of the standard signalling scheme for the channelization code set. The skilled person would thus not recognise at first glance that the formula was erroneous. Furthermore, even if the skilled person did recognise that the formula on page 9 of D14 was wrong, it would not be obvious to them what part of the formula should be corrected and how. In particular, the board agrees with O8 that only a trial-and-error procedure would lead the skilled person to modify the formula in page 9 of D14 by introducing floor brackets around both "P/8" and the whole mathematical expression. This, however, represents an undue burden for the skilled person, contrary to the requirements of Article 83 EPC.

PP further argued that O8's objection that the formula on page 9 of D14 led to the same result for

(P, O) = (11, 5) and (P, O) = (5, 11) had only been raised with O8's letter of 24 April 2023, after the notice of intervention, and should thus not be admitted into the appeal proceedings under Article 12(4) RPBA. In the board's view, however, this argument raised by O8 relates to the objection that the formulas on page 9 of D14 do not provide a workable signalling for O and P; this objection had already been raised in the notice of intervention. Moreover, this argument was filed in response to PP's argument that the formula could be obviously corrected by introducing floor brackets not only around "P/8" but also around the whole mathematical expression. Therefore, this argument has to be considered in the appeal proceedings.

With respect to this argument, PP acknowledged that if the corrected formula were used, there would be four

combinations of P and O for which the code offset indicator (xccs,1, xccs,2, xccs,3) and the code group indicator (xccs,4, xccs,5, xccs,6) would have the same values if P and O were exchanged in the formula. PP further argued in writing that in order to cope with this ambiguity, the skilled person would obviously either choose not to signal four (P, O) pairs or choose to signal these four (P, O) pairs with an additional assignment of 6-bit sequences which were not results of the formulas giving xccs,1, xccs,2, xccs,3 and xccs,4, xccs,5, xccs,6. The board is not convinced by this line of argument. The board holds that the first choice of not signalling four (P, O) pairs would not result in a full implementation of the claimed invention, and that the second choice relies on steps to be performed by the skilled person that go well beyond their common general knowledge.

5.2.3 For these reasons, the board holds that the first implementation example relied on by PP does not represent clear and complete teaching with which the skilled person can implement the claimed invention without undue burden.

5.3 Second embodiment

5.3.1 D14 mentions (page 10, lines 3 to 6) that in a second concept of the invention, the number of HS-PDSCH codes is {1, 3, 5, ..., 15} instead of {1, 2, 3, ..., 15}. This single sentence does not indicate to the skilled person how the channelization code-set information of the HS-SCCH part 1 structure defined in the 3GPP Release 5 specification is modified, or how P and O are signalled. Even if the number of HS-PDSCH codes used is reduced from 15 to 8 with respect to the specification, meaning that the code offset O and the number P of consecutive codes used may each take 8 values, the skilled person is not taught how the signalling is performed. It is also unclear for the skilled person how it is signalled to the user equipment that the HS-PDSCH codes used are restricted to the codes of the specification having only odd numbers, i.e. {1, 3, 5, ..., 15}. The board therefore agrees with O8 that the single sentence on page 10 of D14 does not form clear and complete teaching of a second embodiment with which the skilled person can implement the invention without undue burden.

5.3.2 PP argued in writing that having only odd values for the code numbers, i.e. {1, 3, 5, 7, 9, 11, 13, 15}, reduced the number of values of the code group indicator to 4 values, thus making it possible to spare 1 bit of the code group indicator of the specification, which could then be used for the 16QAM/64QAM signalling, and to leave the formula for the code offset indicator unchanged.

However, the board agrees with O8 that the above-mentioned single sentence in D14 is totally silent about any such way of signalling P and O. Moreover, it is unclear how it is signalled to the user equipment that the HS-PDSCH codes used are those with odd numbers between 1 and 15, since the specification is based on 15 codes with numbers between 1 and 15. Since P defines the number of consecutive codes that are used after the starting code defined by O, the user equipment should be informed of the numbers of the HS-PDSCH codes which should be used as the P consecutive codes.

5.3.3 For these reasons, the board holds that the second implementation example relied on by PP does not represent clear and complete teaching with which the skilled person can implement the claimed invention without undue burden.

5.4 As a consequence of the findings in points 5.2 and 5.3 above, the board decided at the oral proceedings that the priority document D14 was not an enabling disclosure, meaning that the priority claim based on D14 was not valid (Article 87 EPC).

6. Novelty of the main request and auxiliary requests 1 and 2

Documents D3 and D4 were published before the filing date of the PCT application on which the patent is based and are thus prior art under Article 54(2) EPC.

The board agrees with the findings of the decision in point 12.2.1.1 of the Reasons that all the features of claim 1 of the main request are already disclosed in D3 or D4. PP has not challenged these findings in its written and oral submissions on appeal.

The main request is thus not allowable (Article 54 EPC). Since claim 1 of auxiliary requests 1 and 2 is identical to claim 1 of the main request, auxiliary requests 1 and 2 are not allowable either (Article 54 EPC).

7. Admission of auxiliary request 3

PP submitted this request with its statement setting out the grounds of appeal and thus before O8's notice of intervention raising the issue of non-enabling disclosure of the priority document.

PP acknowledged at the oral proceedings that this request was no longer directed to the development of the case, due to the board's opinion about the validity of the priority claim. PP referred to its written submissions.

Taking into account the fact that auxiliary request 3 was not suitable to address the issues related to the validity of the priority claim, the board exercised its discretion under Article 12(4) RPBA and decided at the oral proceedings not to admit auxiliary request 3 into the appeal proceedings.

8. Referral to the Enlarged Board of Appeal

At the oral proceedings, PP raised the following question under Article 112(1)(a) EPC:

"In a situation where a mathematical formula in an example of the description contains errors, is it immaterial to the sufficiency of the disclosure (Art. 83 EPC) if the skilled person could recognize and rectify the errors using his common general knowledge, as laid out by T 171/84?"

In decision T 171/84 of 24 October 1985, the board in charge decided in substance that the application met the requirements of Article 83 EPC because the skilled person could recognise an error in the description, involving an incorrect numerical value in the sole example, and rectify it using their common general knowledge.

In the case in hand, the board found that the skilled person, using their common general knowledge, could neither recognise nor rectify the errors in the formula giving xccs,4, xccs,5, xccs,6, on page 9 of D14 (see point 5.2.2 above). Therefore, the facts in the case in hand are different from in T 171/84, so a decision on the above question is not required under Article 112(1)(a) EPC.

For these reasons, the board decided at the oral proceedings to refuse the request to refer the above-mentioned question to the Enlarged Board of Appeal.

9. Conclusion

The main request and auxiliary requests 1 and 2 are not allowable under Article 54 EPC.

Auxiliary request 3 is not admitted under Article 12(4) RPBA.

The request for a referral to the Enlarged Board of Appeal is refused (Article 112(1)(a) EPC).