T 0694/11 (Random hopping patterns of sub-carriers) of 25.9.2012

Summary of Facts and Submissions

I. The appeal is against the decision of the examining division, posted on 4 November 2010, refusing European patent application No. 05855326.4 on the grounds of insufficiency of disclosure (Article 83 EPC) and lack of clarity and support of the claims (Article 84 EPC).

II. Notice of appeal was received on 12 January 2011 and the appeal fee was paid on the same day. The statement setting out the grounds of appeal was received on 11 March 2011. The appellant requested that the decision of the examining division be set aside and that a patent be granted on the basis of a set of amended claims 1 to 34 submitted as a new main request with the statement setting out the grounds of appeal. In addition, oral proceedings were requested as an auxiliary measure. By letter received 28 April 2011, the appellant further requested to take into account the documents cited in the parallel US case.

III. A summons to oral proceedings scheduled for

25 September 2012 was issued on 9 July 2012. In an annex to this summons pursuant to Article 15(1) RPBA, the board expressed its preliminary opinion that the application did not meet the requirements of

Articles 83 and 84 EPC. The board further indicated its intention to remit the case to the department of first instance for further prosecution if, during the oral proceedings, it came to the conclusion that the application fulfilled the requirements of

Articles 83 and 84 EPC.

IV. With a letter received 24 August 2012, the appellant filed a set of amended claims 1 to 34 as an auxiliary request. The appellant further submitted arguments in support of the main and auxiliary requests.

V. Oral proceedings were held as scheduled on

25 September 2012. The appellant requested that the decision under appeal be set aside and that a patent be granted on the basis of the main request as filed with the statement setting out the grounds of appeal on 11 March 2011 or on the basis of the auxiliary request as filed with letter dated 24 August 2012. At the end of the oral proceedings, the decision of the board was announced.

VI. Independent claim 1 of the main request reads as follows:

"A method for generating random hopping patterns, comprising:

determining a first number of sub-carriers;

determining a second number of hop ports;

determining a third number of seeds;

generating at least one hopping pattern based on the first number of sub-carriers, the second number of hop ports, and the third number of seeds wherein the hopping pattern is generated using a Feistel Network;

and

transmitting a signal with a transmitter unit according to the hopping pattern."

The main request includes further independent claims 12, 23, and 34 seeking protection for a corresponding processor, apparatus and computer-readable medium, respectively.

Independent claim 1 of the auxiliary request reads as follows:

"A method for generating random hopping patterns for mapping a second number of hop ports to a first number of subcarriers for forward link data transmission from an access point to an access terminal and/or for reverse link data transmission from an access terminal to an access point, comprising:

determining the first number of sub-carriers; determining the second number of hop ports;

determining a third number of seeds; and

generating at least one hopping pattern based on the first number of sub-carriers, the second number of hop ports, and the third number of seeds, wherein the hopping pattern is generated using a Feistel Network."

The auxiliary request includes further independent claims 12, 23, and 34 seeking protection for a corresponding processor, apparatus and computer-readable medium, respectively.

Reasons for the Decision

1. The appeal is admissible.

2. Clarity of the term "hop port"

2.1 The application has been refused based, inter alia, on the reasons that the term hop port present in the claims had no well-defined meaning in the field of telecommunications at the priority date and was not defined or explained in the description.

2.2 The appellant filed several documents providing a definition and explanation of the concept of hop ports, none of them however having being published before the priority date of the present application

(22 December 2004). In particular, the appellant argued that the inclusion of the term hop port in the terminology of the Ultra Mobile Broadband (UMB) portion of the 3GPP2 specification in August 2007 and its use in an IEEE presentation dated November 2005 evidenced that the term hop port has been known and used in common practice by skilled persons well before the publication dates of these documents. The board is not convinced by this argument since the lapse of eleven months between the priority date of the present application and the IEEE presentation represents a rather important amount of time in the rapidly evolving field of mobile communications.

2.3 The appellant however convincingly argued that the meaning of the term hop port is explained in the description itself.

In that respect, the appellant first pointed out to the paragraphs [002], [005] and [0102] of the application as published, wherein it is stated that the invention relates to the generation of random hopping patterns in a multiple-access communication system, in particular patterns of nearby frequency sub-carriers for block hopping, the aim of the hopping being to ensure frequency diversity. Thus, the described hopping was clearly recognizable by a skilled person as a frequency hopping, a conclusion to which the board adheres.

The appellant further based its argumentation on the paragraphs [024] and [025] which define the hop ports by their properties. These passages teaches that a set of hop ports, numbered 0 to NFFT-NGUARD-1, is mapped, according to a hopping sequence, to a set of usable sub-carriers and that a subcarrier index Hij(p) corresponds to a hop port index "p" for the jthmodulation symbol in superframe index "i", p being an index between 0 and NFFT-NGUARD-1. The parameters NFFT and NGUARD have a well-established meaning in the field of OFDM, referred to throughout the description, and designate the number of sub-carriers and the number of guard sub-carriers, i.e. sub-carriers which are not modulated, respectively. There are thus NFFT-NGUARD usable sub-carriers which are mapped, according to paragraph [025], to the same number of hop ports. It is further well known in OFDM that data is transmitted in superframes consisting in sequences of OFDM symbols, and that an OFDM symbol is modulated by using

NFFT-NGUARD subcarriers.

The person skilled in the art of OFDM would directly deduce from the above mentioned paragraphs that an OFDM symbol, defined by the time indices i (numbering of the superframe) and j (numbering of the symbol within the superframe), is assigned a set of NFFT-NGUARD hop ports numbered 0 to NFFT-NGUARD-1 and that the hopping sequence, or mapping between these hop ports and subcarriers, defines which subcarrier Hij(p) among the usable subcarriers will be used as pthsubcarrier for the symbol, thereby achieving a frequency hopping of the subcarriers.

2.4 Thus, the board judges that the term "hop port" has a clear meaning for the skilled person, based on the description, and that the use of this term in the claims does not render their subject-matter unclear (Article 84 EPC).

3. Insufficiency of disclosure

The application has also been refused because the application did not disclose the invention in a manner sufficiently clear and complete for it to be carried out by a skilled person (Article 83 EPC). In particular, the decision under appeal stated that the calculation defined in paragraph [025] could not be seen to result in any hopping and could not be carried out since the calculation was based on parameters NFFT, NGUARD, HijGLOBAL and HijSECTOR which were unknown to the skilled person.

The appellant demonstrated (see section 2.3 above) that the mapping of a set of hop ports to a set of subcarriers defined by the paragraphs [024] and [025] represents a frequency hopping of the subcarriers used to transmit a symbol when the mapping changes from one symbol to the next according to the generated hopping patterns. Moreover the appellant plausibly argued that the paragraphs [024] to [034] disclose an embodiment enabling the skilled person to calculate the hopping pattern used to map the hop ports to the usable subcarriers, by using the formula

Hij(p)= NGUARD/2 + HijGLOBAL(HijSECTOR(p)) (see paragraph [025]).

HijSECTOR(.) and HijGlobal(.) are permutation functions of the set {0,1,2,...NFFT-NGUARD-1}. The parameters NFFT and NGUARD had a well-known meaning in the field of OFDM at the priority date of the present application (see section 2.3 above).

FLSectorHopSeed, SECTOR-PN-OFFSET, and FLIntraCellCommonHopping are parameters defined in paragraphs [026] to [034] and used in the generation of the permutation functions HijSECTOR(.) and HijGlobal(.):

- SECTOR-PN-OFFSET is an offset parameter used in the calculation of HijSECTOR(p) (see paragraph [026], first sentence) and in the generation of seeds for the Feistel network (see paragraph [028], alinea 2.);

- FLIntraCellCommonHopping is a boolean parameter having the values "off" or "on" used in the calculation of the permutation HijSECTOR(.) (see paragraphs [026], [030] and [032]);

- FLSectorHopSeed is a seed used in the Feistel network.

The calculation of the permutation function HijSECTOR(.), or sector dependent permutation, is described in paragraphs [027], [030] and [032].

The calculation of the permutation function HijGLOBAL(.) is described in paragraphs [028] and [029], based on a three stage Feistel network, known per se.

The board therefore judges that the description is clear and sufficient enough to enable the skilled person to carry out the calculation of Hij(p) defined in paragraph [025].

4. Main request

Claim 1 according to the main request relates to a method for generating random hopping patterns. The method comprises steps for determining a number of sub-carriers, a number of hop ports and a number of seeds and generating a hopping pattern based on these numbers and using a Feistel network. Claim 1 however does not define what is being hopped by the generated pattern, i.e. claim 1 does not define clearly that the hopping pattern represents a mapping between the hop ports and the subcarriers, as it is described throughout the description.

Moreover, claim 1 contains a step of transmitting a signal according to the hopping pattern. Since the pattern is not defined clearly (see the above paragraph), this step also lacks clarity.

For these reasons, presented to the appellant during the oral proceedings, the board judges that claim 1 does not meet the requirements of Article 84 EPC and that, as a consequence, the main request is not allowable.

5. Auxiliary request

Claim 1 according to the auxiliary request does define that the random hopping pattern achieves a mapping between the hop ports and the subcarriers, the subcarriers being used for data transmission. The objections raised in section 4 above are thus overcome by the wording of claim 1. Independent claims 1, 12, 23 and 34 contain the same features as claim 1 but expressed in terms of claims for a programmed processor, an apparatus and a computer readable medium. The board therefore judges that the auxiliary request meets the requirements of Article 84 EPC.

6. Conclusion

The application and the claims according to the auxiliary request meet the requirements of

Articles 83 and 84 EPC. Since no search and no examination with respect to novelty and inventive step have been performed so far, the board decides, as indicated in the annex accompanying the summons to oral proceedings (see section 4), to remit the case to the department of first instance for further prosecution.

ORDER

For these reasons it is decided that:

1. The decision under appeal is set aside.

2. The case is remitted to the department of first instance for further prosecution on the basis of the auxiliary request as filed with letter dated 24 August 2012.