England and Wales High Court (Patents Court) Decisions

Technical background to DSL/ common general knowledge

Introduction to DSL

DSL Standardisation

DSL Management and reporting Systems

The Witness

JUDGMENT PART A – THE 268 PATENT

Technical background to the 268 Patent/common knowledge at the priority date

i)                    Starting with the transmitter shown on the left hand side of the diagram, at the top level the Mux Data Frame (‘MDF’) is formed by multiplexing data received from the higher layers in the protocol stack. MDFs consist of one byte of overhead data followed by a given (but variable) number of bytes of multiplexed higher level data. Multiplexing is the process where multiple streams of data are combined into a single bit stream. The overhead in the diagram is shown as the first red byte with the remainder payload within the MDF shown as white. At this level the system uses the position of bytes in the frame to identify which amongst them are overhead. The MDFs are constructed by the transmitter at a rate of 4kHz.

ii)                  The next step is that the bits forming the MDFs are scrambled . Scrambling is a common process in telecommunications. One reason it is beneficial in digital transmission is that transmitters and receivers are not efficient at transmitting long sequences of 1s or 0s. ADSL uses a scrambler in which the input bit stream is scrambled using an algorithm in which the output bits are dependent not only on the value of the input bit but also that of previous inputs. The input bit is thus scrambled across a large number of output bits – there is no simple one to one correlation between input and output bits. Every bit that comes in continues to have an effect in the system as the effect goes round and round within the scrambler. This can be seen from the following diagram in T1.413 Issue 2:

iii)                The binary data streams are scrambled using an algorithm in which the output (d’ _n ) is dependent on the input (d _n ) and the n-18 ^th and n-23 ^rd outputs as above. It is a convolutional encoding scheme. Following scrambling there is no single place you can point to and say that is where a particular bit from the MDF has ended up. It is for this reason that the diagram depicts scrambled data spreading out beyond the equivalent of the two MDFs shown at the top level of the diagram with tramlines above and below the scrambled data to depict an equivalent number of bits to that which made up the two MDFs.

iv)                The next step is the formation of the Forward Error Correction (“FEC”) codeword. FEC is a way to introduce redundancy such that when errors occur not only are they detected but they can also be corrected as long as there are not too many of them. The error correcting code can completely correct the errors so long as the number of errors contained within the data is not above a threshold. The FEC bytes are additional bytes which are added onto the end of the scrambled data over which the FEC has been calculated (shown in the diagram in blue). The consequence is that the volume of data expands at this point.

v)                  The next step is the creation of the FEC output data frame – the FEC codeword is segmented into frames.

vi)                Interleaving is then carried out on the FEC output data frames. The interleaving assists error correction in the presence of certain types of noise on the line – in particular errors that come in bursts. The basic idea of interleaving is that the bytes are shuffled with the result that an error burst does not overly affect one FEC codeword. A side-effect of interleaving is the introduction of delay (as bits are shuffled back from when the FEC frame would have been fully transmitted). An illustration of interleaving taken from Dr Jacobsen’s first report is shown below:

vii)              Typically, interleaving takes place across many FEC codewords rather than just the four shown in the diagram above. The interleaved bits are then ordered into the tones to produce a constellation encoder input data frame. This is the last place in the transmission scheme where the system deals in bits.

viii)            The constellation encoder takes the tone ordered bits and translates them into a set of complex numbers which represent points on a constellation diagram. Depending on the scheme used, a particular point in the constellation represented by a complex number can encode multiple bits. The numbers are used to modulate the tones in the frequency domain to enable transmission.

ix)                The complex numbers are then subjected to an Inverse Discrete Fourier Transform (“IDFT”). This is used to generate a set of points which are basically a set of samples of the waveform to be transmitted on the wire.

x)                  The final step before transmission is for the set of points to go through a digital to analogue converter (“DAC”) before it is transmitted on the wire. The signal that is transmitted is formed into a superframe consisting of 68 data symbols followed by a synchronization symbol. These provide windows of time within which a particular waveform is on the line and can be sampled by the receiver. The synchronization symbol helps the receiver to identify the timing boundaries between superframes. The symbols thus transmitted are at a slightly higher rate than 4kHz to allow for the insertion of the synchronization symbol. The rate at this level is 4.058 kHz.

xi)                The actual wave that is transmitted across the twisted pair shown at the bottom of the diagram is analogue. Starting at the bottom of the diagram on the right hand side, the received signal is processed using an analogue to digital converter to recover a set of points (or samples) corresponding to the waveform that was transmitted. They are then processed by a discrete Fourier transform to recover the complex numbers corresponding to the constellation points. There is a limited range of messages that could be transmitted and the receiving end knows that only particular modulated signals are valid and assumes that the nearest one to that is the one that was sent and interprets it accordingly.

xii)              The constellation decoder then recovers the constellation encoder input data frame from the complex numbers and a bit stream is again formed. This is then de-merged and the bits from the various tones assembled into an interleaved bit stream.

xiii)            It is de-interleaved and the FEC output data frames are recovered. The FEC codewords are identified and forward error correction is carried out to attempt to correct any errors in the transmitted bit stream.

xiv)            At that point a scrambled stream of data is formed which is then de-scrambled (by applying the inverse of the convolutional scrambling process) before the MDFs shown on the top right hand side are reassembled.

xv)              Because the overhead in the reassembled MDFs is to be found in the first byte of the MDF, it can then be identified on the basis of its position within the MDF and used as appropriate.

The 268 Patent

“In a presently-used form of ADSL communications, sixty eight data frames and one synchronization frame form a "superframe" that is repeated throughout the transmission. The data frames carry the data that is to be transmitted; the synchronization or "sync" frame provides a known bit sequence that is used to synchronize the transmitting and receiving modems and that also facilitates determination of transmission subchannel characteristics such as signal-to-noise ratio ("SNR"), among others.”

“A superframe is 17 milliseconds in duration. A frame is effectively 250 microseconds in duration (or conversely, the frame rate is approximately 4 kHz) and is made up of a collection of bytes (with one byte corresponding to 8 bits).”

i)                    Since one byte out of each frame in each superframe during conventional DSL communications is dedicated to overhead data, the corresponding overhead data rate is invariably fixed at 32 kbps and is not changed when either the payload data transmission rate changes or when no actual EOC or AOC data are available for inclusion in the frame.

ii)                  Some telephone lines used in DSL communications are of such poor quality that the maximum possible DSL data transmission rate using such lines may not exceed 128 kbps. This means that when DSL communications are carried out over such poor quality lines, an undesirably large proportion (e.g., up to 25%) of the DSL communications system's throughput may be used to transmit overhead data.

iii)                At any given time during a given communications session, the total communications bandwidth is constant. This means that communications bandwidth that otherwise would be available to transmit payload data is unnecessarily consumed in transmitting overhead data.

“ provide a multicarrier communications system and method that overcome the aforesaid and/or other disadvantages and drawbacks of the prior art, and more specifically, to provide such a system and method wherein the overhead data transmission rate during a communications session may be changed and/or selected.”

“ In the system and method of the present invention, the overhead data transmission rate may be changed and/or selected. More specifically, this rate may be selected during an initial negotiation process and/or during a steady state mode of operation.”

“ Whereas in the prior art, the first byte in each frame is dedicated to overhead data regardless of whether there is a need to transport overhead data or not, in this embodiment of the present invention, the overhead data transmission rate is determined during start-up and can be modified during steady state mode. ”

“[1] A method of controlling a transmission rate of overhead data bits

[2] in a sequence of frames in a digital subscriber line communication

[3] using multicarrier modulation,

the method being characterized by :

[4] programming the transmission rate between a minimum rate and a maximum rate

[5] and selecting a value for a first parameter (n _max ) that specifies which frames in the sequence of frames contain overhead bits and which frames in the sequence of frames do not contain overhead bits.”

The skilled addressee of the 268 Patent

i)                    the skilled person in relation to the 268 Patent is a DSL communications systems engineer with experience in DSL systems architecture and an interest in the design and implementation of DSL transceivers;

ii)                  The skilled person may be a DSL systems architect, in which case she or he has a strong understanding of transceiver hardware and software architectures and has the skills to convert DSL product requirements into a DSL system architecture specification. Product requirements may include standards requirements;

iii)                Alternatively the skilled person may be a DSL software or hardware architect, depending on whether the framing functionality is predominantly implemented using software or hardware. The skilled person has a strong understanding of DSL transceiver software/hardware architectures, and possesses the knowledge required to map product requirements to a DSL software/hardware architecture specification.

The issues in dispute in relation to the 268 Patent

i)                    Interpretation of the following language in Claim 1: “frame”; “specifies”; “Nmax”;

ii)                  Whether the 268 Patent was obvious at the priority date in the light of the cited prior art (“Alabama”);

iii)                If the 268 Patent was obvious, whether a conditional amendment to the 268 Patent is permissible;

iv)                Infringement - whether the 268 Patent is essential to (a) ADSL2/2+ and/or (b) VDSL2;

Interpretation of Claim 1

Legal principles

A term of art?

“…because of the addition of FEC redundancy bytes and data interleaving, the data symbols (i.e. bit level data prior to constellation encoding) have different structural appearance at the three reference points through the transmitter.”

“Frame” in the context of the 268 Patent

“There appears to be an issue with Claim 1 in that the “frames” in the preamble do not appear to be the same "frames" as referred to in the remainder of the claim. The skilled person would appreciate that the general disclosure of the patent uses the term “frame” sometimes to refer to what the skilled person would understand to be a mux data frame in ADSL ( see, e.g. , ¶ [0012]), and other times to refer to what the skilled person would understand to be the frames mapped to DMT symbols ( see, e.g. , ¶ [0009]). What matters is the apportionment between user data and overhead data within the overall transmission system. For my following comments, I shall assume that the references to “frames” must be interpreted with a certain amount of flexibility, as this is the only way that the claim can make any reasonable sense.”

i)                    the specification refers only to the types of overhead included in the fast and sync bytes.

ii)                  Each of the embodiments in the 268 Patent (ie Figure 3, Figure 4, Table 1 and Table 2) are concerned with the allocation of overhead data carried in the fast and sync bytes in the MDFs.

iii)                That overhead typically only has meaning at the layer of the system at which it is inserted (and extracted). Lower processes will result in the contents of the MDFs not being identifiable (or at least not meaningfully).

iv)                Given that Claim 1 requires the first parameter to specify which frames in a sequence of frames contain overhead bits and which do not, that implies technically that there cannot be a disconnect between the overhead data and the frames that are specified to contain it. At each layer the input data received from the previous layer comprises ‘payload’ data and additional overhead is added to it.

“Q. If you look at paragraph 17, you see that the patent explains that the object of the invention is summarised, and it says it is to overcome the aforesaid disadvantages.

A.     Yes, I see that.

Q. So, that disadvantage as we have just been talking about is the fixed mux data frame level overhead, the sync and fast bytes; yes?

A. Pause: It seems to be focused on the fact that there is one sync or fast byte in each mux data frame.

Q. Yes, that is the disadvantage it identifies that it says the invention overcomes.

A. Correct. So there is too much of the bit rate consumed by the transmission of the fast and sync bytes.”

“specifies”

“n _max ”

“Where the European patent application contains drawings including reference signs, the technical features specified in the claims shall preferably be followed by such reference signs relating to these features, placed in parentheses, if the intelligibility of the claim can thereby be increased. These reference signs shall not be construed as limiting the claim.”

The prior art citied against the 268 Patent (“Alabama”)

Here the MDF is shown as having one sync byte (S) per MDF followed by 10 payload bytes (P).

Anticipation by Alabama

Obviousness in the light of Alabama

ZyXEL’s case in outline

“The G.DMT framing structure exhibits poor bandwidth efficiency when applied to the low bit rates required to provide service on the longest loops envisioned for G.Lite.”

…

Factors causing low efficiency:

·          One sync byte per frame

·          At least one FEC overhead byte per frame…”

“The inventors have further realised that the requirement for one sync byte per frame is wasteful in many situations. The inventors provide an option to include a sync byte just once for several frames, rather than once per frame.”

This, it suggested, was exactly the point Dr Jacobsen was making.

TQ Delta’s case in outline

Discussion

Conventional obviousness

“18 Q. Now, doctor, not only are you muddling up overhead by trying
19 to look at a different level to identify a frame, this table
20 does not even treat frames consistently as between the left
21 hand pair of columns and the right; does it?

22 A. Well, no, and, as I explained, the objective was to show how
23 would these things roughly line up, if I were to carry the
24 Alabama example out to an entire Superframe's length.”

(T3/399/18-24)

“3 Q. You see, doctor, what I have to suggest to you is that you are
4 not being consistent in this table, and you are jumping
5 between looking at mux data frames when you are giving a
6 number to the G.DMT, and then flipping down to a different
7 level in the processing to the DMT symbol or whatever you want
8 to call it, but you are not looking at the same thing when you
9 try and line up where the sync byte is and give it a frame
10 number in the two right-hand columns?

11 A. Well, I do not disagree with you and I am wondering if you
12 have interpreted the frame number column as applying to the
13 Alabama columns, that was not my intention. I was giving that
14 frame number to show that the G.DMT sync byte index lines up
15 with that, so that the demarcation between the two is that
16 line between the G.DMT framing and the Alabama framing. I was
17 trying to show where they are in time.”

(T3/4034/3-17)

25 Q. So, this is right, is it not, Alabama does address the issue

2 of the overly high proportion of overhead at low line rates;
3 yes?

4 A. It does, yes.

5 Q. But it does not do so by providing for the space allocated to
6 the sync and fast bytes in some of the frames to be allocated
7 to payload? That is right, is it not?

8 A. Well, it defines this longer mux data frame which -- Yes,
9 that is right.

10 Q. And the parameter SB does not specify which of the mux data
11 frames the sync and/or fast bytes are and are not; agreed?

12 A. It does not specify their contents, is that what you asked?

13 Q. It does not specify which of the mux data frames has a sync
14 and a fast byte and which do not?

15 A. Not of the mux data frames, no.

“It follows from these considerations that a mere arbitrary choice from this host of possible solutions of such a "technical problem" cannot involve an inventive step (see also e.g. T 220/84 of 18 March 1986, No. 7 of the reasons). In other words, the Board holds that, in view of the underlying general legal principle set out in point 2.4.2 above, the selection of such compounds, in order to be patentable, must not be arbitrary but must be justified by a hitherto unknown technical effect which is caused by those structural features which distinguish the claimed compounds from the numerous other compounds.” 

“i) Article 56 of the EPC is in part based on the underlying principle that the scope of the patent monopoly must be justified by the patentee's contribution to the art;

ii) If the alleged contribution is a technical effect which is not common to substantially everything covered by a claim, it cannot be used to formulate the question for the purposes of judging obviousness;

iii) In such circumstances the claim must either be restricted to the subject matter which makes good the technical contribution, or a different technical solution common to the whole claim must be found;

iv) A selection from the prior art which is purely arbitrary and cannot be justified by some useful technical property is likely to be held to be obvious because it does not make a real technical advance;”

Application to the facts

i)                    The concept of the 268 Patent is “fixed overhead transmission is wasteful, so control it by not including an overhead byte in every frame”. The only other feature of the claim, specifying which bytes are where, is necessary in any deterministic system.

ii)                  The skilled person finds the same inventive concept in Alabama – as described in one of the author’s patent applications “the requirement for one sync byte per frame is wasteful in many situations. The inventors provide an option to include a sync byte just once for several frames, rather than once per frame.”

iii)                The precise mechanisms of implementing the inventive concept  - using an MDF rate of 1 kHz then rebuilding the frames at 4 KHz for transmission, or keeping the MDF rate at 4 KHz and inserting sync bytes every 4 frames - are irrelevant. For all material purposes they come to the same thing.

ZyXEL’s four alternative cases

Can ZyXEL rely on these alternative cases?

i)                    They were not foreshadowed in any of the three reports of Dr Jacobsen. They were first advanced during cross-examination, or in certain instances during re-examination.

ii)                  They each raised technical issues. Had they been set out earlier, they would have been dealt with from a technical perspective in the reports of Dr Ginis, or at the very least, they would have been discussed in detail before the trial and are likely to have been the subject of evidence from Dr Ginis.

iii)                They were in substance unpleaded anticipation attacks (and had been expressly advanced on that basis).

iv)                The arguments based upon FEC frame level were not part of Alabama’s proposal at all. Rather, they relied upon aspects of the pre-existing system, contained in the ADSL1 standard as Dr Ginis pointed out during his cross-examination. This was common general knowledge at the priority date. However ZyXEL had disclaimed reliance on any case based on common general knowledge alone.

FEC frame level (Reference point B) part 1

i)                     In Alabama, FEC overhead can be turned off, in which case its FEC frames will not contain FEC bytes. Similarly, interleaving is optional and can also be disregarded.

ii)                  In the case where MDFs are created at 1 kHz and FEC frames at the ordinary rate of 4 kHz, the contents of 1 MDF will be split into 4 FEC frames. The only difference between the appearance of the bits is that scrambling has taken place, but according to ZyXEL, this does not affect the position of the bits and can be disregarded for purposes of the patent.

iii)                In such a case, ZyXEL contended that only every fourth FEC frame will contain a fast byte.

FEC frame level (Reference point B) part 2

MDF level (reference point A) part 1

MDF level (reference point A) part 2

Conclusion

Conditional amendment

Infringement

JUDGMENT PART B –  THE 430 PATENT

Technical background relevant to Patent 430 / common general knowledge at the priority date

CRCs

The 430 Patent

“This corresponds to approximately 30 per cent of computed CRCs being in error if the CRC is computed every 17 ms. The G.992.3 ADSL standard requires that the CRC is computed every 15 to 20 msecs. In ADSL  2 and ADSL 2 systems, the period of the CRC computation is called the period of the overhead channel (PERp). The G.992.3 standard requires that

15 ms <= PERp <= 20 ms.”

“Object (sic) of this invention relates to calculating and reporting communication errors and, more particularly, to a method or a module for calculating or reporting CRC anomalies in a consistent manner for all communication connections in a network independent of data rate or the CRC computation period (e.g. the PERp value) of each individual connection.”

Claims in issue

“[1] Method for Cyclic Redundancy Checksum, hereinafter referred to as CRC, anomaly counter normalization comprising:”

[2] identifying a CRC anomaly when a local CRC octet, which is computed based on a received bit stream, is not identical to a received CRC octet.

[3] normalising the CRC anomaly counter based on a value for a CRC computation period, hereinafter referred to as PERp

[4] wherein the normalising of the CRC anomaly counter comprises incrementing the CRC anomaly counter by a value of M wherein the value of M is equal to PERp/K, where K is a positive integer.

Issues in dispute in relation to the 430 Patent

i)                    Interpretation of “normalising” in Claim 1;

ii)                  Infringement, which depends on the interpretation of normalising.

iii)                The identity and attributes of the skilled person;

iv)                Common general knowledge of the changes in respect of the CRC computation period introduced by changes in the standards

v)                  Obviousness in the light of the cited prior art (ADSL2/02)

Interpretation of “normalising” in Claim 1

“[0042] K=15 ms and PERp=10 ms: CRC computations are combined in groups of ceiling(15/10)=2 CRC computations. The first 2 CRC computations are the first group, the second 2 CRC computations are the second group, and so on. One or more CRC anomalies in a group are counted as 1 normalised CRC anomaly.”

“Q. So one can see that outside that window, one is getting the
benefit of the normalisation because you have had the effect
of scaling it so as to constrain any variation to be within   in this case, 36 to 27, yes?

A. That is right.”

Infringement

The skilled addressee of the 430 Patent

Legal principles

i)                    A patent specification is addressed to those likely to have a real and practical interest in the subject matter of the invention (which includes making it as well as putting it into practice) ( per Lord Diplock in Catnic Components v Hill & Smith Ltd [1982] RPC 183 at 242 )

… A fiction in patent law is that the notional uninventive skilled man in the art is deemed to have read and assimilated any piece of prior art pleaded by the party attacking the patent claim . If the invention is obvious to that person in the light of a particular piece of prior art, the claim is invalid. It is no answer to say that in real life the prior art would never have come to the attention of a worker in the field, for example because it was tucked away on the top shelf of a public library or because it was in a language which nobody in the art knew. The notional skilled person is assumed to have read and understood the contents of the prior art. However that does not mean that all prior art will be considered equally interesting. The notional skilled person is assumed to be interested in the field of technology covered by the patent in suit, but he is not assumed to know or suspect in advance of reading it that any particular piece of prior art has the answer to a problem he faces or is relevant to it. He comes to the prior art without any preconceptions and, in particular, without any expectation that it offers him a solution to any problem he has in mind…. (emphasis added).

Internet service providers

“[0005] Digital subscriber line service providers use CRC anomaly reporting as a way to diagnose and detect problematic service conditions. For example, an ADSL service provider may use SESs as a way to detect an ADSL connection that is experiencing problems. For example, an ADSL service provider may specify that if an ADSL subscriber is experiencing more than 30 SESs in a 1 -minute period, the ADSL connection needs to be repaired. For this reason, it is important that an SES is reported in a consistent manner across all connections in the service provider network.

[0006] As discussed above, if an ADSL system is determining CRCs every 17 ms (the PERp as required by the standard), Severely Errored Seconds (SESs) are defined as 18 or more CRC anomalies in a 1-second interval, then an SES will occur whenever approximately 30 percent of the computed CRCs are in error in a 1-second interval. But if, for example, CRCs are computed every 2 ms, and a SES is still defined as 18 or more CRC anomalies in a 1-second 40 interval, then 18 CRC anomalies will correspond to only 3.6 percent of a computed CRC being in error. In this case, the service provider may receive a repair alarm and dispatch a network technician to fix a connection that is only experiencing a small number of errors”.

“Q. Anything that is required, so it is given a capital letter "R", for example, and is thus mandatory, is something that any skilled person who was involved in error management, for example, in operating an ISP at the priority date, would need to be very familiar with?

 A.  It would be a reasonable assumption for the kind of person you describe to pay particular attention to those parts.”

Common general knowledge –CRCs and SESs

“for someone that intends to study and understand, implement, G.992.1 transceivers and, more precisely, wanting to understand the management functions of such transceivers, the G.997.1 document would indeed provide the detailed specification.”

237.           The impact on user experience from an SES was also uncertain. If the bytes in error were simply dummy bytes conveying no information (e.g. if the DSL was idle), then there would be no impact on user experience. If the bytes in error corresponded to a voice application with a high tolerance for lost packets, then the impact on user experience would be minor. If the bytes in error corresponded to a critical video frame of a live-streamed sports event, then the impact on user experience could be significant.

CRC anomalies expressed as a percentage

“The logic that I applied, that I believe the skilled person applied would be first to see that number 18 and think, “Why 18” (because any time you see a constant, I think the skilled person wonders where the constant came from) and then, would look at ADSL and realise, based on the structure of the overhead channel and the fact that the CRC has transmitted once every 17 ms, then would work out “okay that is about 30%. I understand that is the traditional level to declare a severely errored second.”

Perception of the problem – legal principles

The posing of a new problem did not represent a contribution to the inventive merits of the solution if it could have been posed by the average person skilled in the art (T 109/82, OJ 1984, 473).  It also had to be taken into consideration that it was the normal task of the skilled person to be constantly occupied with the elimination of deficiencies, the overcoming of drawbacks and the achievement of improvements of known devices and/or products (see T 15/81, OJ 1982, 2; T 195/84, OJ 1986, 121).  In T 532/88 the board confirmed the established principle that to address a problem simply by looking for ways of overcoming difficulties arising in the course of routine work did not constitute inventiveness.

[…]

In T 971/92 the board emphasised that the appreciation of conventional technical problems which formed the basis of the normal activities of the notional person skilled in the art, such as the removal of shortcomings, the optimisation of parameters or the saving of energy or time, could not involve an inventive step.  The appreciation of a technical problem could thus only contribute to the inventive step in very exceptional circumstances.

Obviousness in the light of ADSL2/02

Normalising the CRC anomaly counter based on a value for a CRC computation period, hereinafter referred to as PERp, wherein the normalising of the CRC anomaly counter comprises incrementing the CRC anomaly counter by a value of M wherein the value M is equal to PERp/K, where K is a positive integer.

TQ Delta’s submissions in outline

i)                    She was instructed to approach the prior art with a focus on how a skilled person would suggest to improve CRC reporting. As a matter of fact she approached her task even more narrowly – only considering Severely Errored Seconds.

ii)                  She assumed a superhuman ability of the skilled person to wade through a long and complex standard, assimilating the detail and piecing together consequences. Not only did the skilled person assimilate the material but he or she was also equipped to cherry-pick points from different places in the standardisation landscape. There are 13 cross-referenced documents in the ADSL2 prior art standard. The addressee knew what to consider and what to ignore, apparently questioned each and every constant they saw in the standards, and identified all current and potential problems including a problem with Severely Errored Seconds.

iii)                The approach was riddled with hindsight and speculation: a classic step-by-step approach, ignoring many matters, focusing on others.

ZyXEL’s submissions in outline

Discussion

Focus on CRCs/SESs

Q. Okay. Let me put something else to you. If you were considering an automated system of the kind we have been discussing, that you mention in paragraph 253, which you wanted to implement as an ISP to identify problematic lines, you would need to consider, would you not, as a matter of course, whether the information you were relying on, in this case severely errored second counters, was being reported in a consistent way across all the lines on your network?

A. Allow me a few seconds. (Pause) I think it is indeed a desire of the software engineers or the systems engineers who are designing such systems, to rely on consistent parameters. So I would agree that there is the motivation to know, to make sure that quantities such as severely errored seconds, are consistent.

“I think that the immediate, let us say, concern of the immediate motivation of an individual that is working for an internet service provider and who is seeing that there is this new standard, ADSL2, which is now coming into the market and possibly equipment needs to be included in the network, would be to look at whether severely errored seconds are reported and whether they are available.”

Superhuman ability/cherry picking

i)                    The skilled person would note that the CRC octet is in the first octet in the overhead channel, as it was before, so the period of the CRC checks was the period of the overhead channel. This is shown in Table 7-14 on p40 of ADSL2/02. Dr Ginis agreed that this is where the skilled person would expect to find it and that this is what she or he would be looking for; 

ii)                  The skilled person would find the overhead channel period which is explicitly identified in Table 7-7, on p32, as PERp. She or he would immediately see that PERp is variable, but that the scope for variation is fixed by the throttle of 15-20ms in Table 7-8, on p33.

Step by step approach and hindsight

Secondary evidence – events subsequent to the publication of ADSL2/02

As I explained above when considering developments of ADSL2/02 without knowledge of the ’430 Patent or future developments in ADSL, the normalizing step merely recites one of solutions the skilled person would have recognized, as a matter of routine, for the problem of different receivers declaring SESs for different percentages of CRC checks being in error.  The skilled person would have understood this to be a solution within ADSL2/02 to ensure that error reporting was consistent (i.e., SES declared at a 30% CRC error percentage) across all allowed values of PERp.  Moreover, as I explained above, the skilled person would have understood the importance of solving this problem for later versions of DSL in which the PERp could be expected to vary even more than between 15 and 20 ms, such as for the higher-bit-rate standards (e.g., VDSL2) already being developed as of the priority date. 

Overall conclusions

i)                    The 268 Patent is valid and infringed.

ii)                  The 430 Patent is obvious in the light of ADSL2/02.

iii)                If the 430 Patent had been valid, it would have been infringed.

Annex 1

Standards of relevance to the 268 Patent and the 430 Patent