Adaptive Spectrum and Signal Alignment Inc. (Respondent/Appellant) v British Telecommunications Plc (Appellant/ Respondent)
| Jurisdiction | England & Wales |
| Judge | Lord Justice Floyd,Sir Stanley Burnton,Lord Justice Patten |
| Judgment Date | 11 November 2014 |
| Neutral Citation | [2014] EWCA Civ 1462 |
| Court | Court of Appeal (Civil Division) |
| Docket Number | >Case No: A3 2014/0344 |
| Date | 11 November 2014 |
[2014] EWCA Civ 1462
Lord Justice Patten
Lord Justice Floyd
and
Sir Stanley Burnton
>Case No: A3 2014/0344
A3 2014/0359
IN THE COURT OF APPEAL (CIVIL DIVISION)
ON APPEAL FROM THE HIGH COURT OF JUSTICE
CHANCERY DIVISION
PATENTS COURT
MR JUSTICE BIRSS
Royal Courts of Justice
Strand, London, WC2A 2LL
Roger Wyand QC and Hugo Cuddigan (instructed by Bird & Bird LLP) for British Telecommunications PLC
Iain Purvis QC and Joe Delaney (instructed by Wragge Lawrence Graham & Co LLP) for Adaptive Spectrum and Signal Alignment Inc.
Hearing date: 7–9 October 2014
Introduction
This is an appeal from a decision of Birss J dated 3 December 2013 in a patent action. There are two patents in suit, both in the name of the claimant, Adaptive Spectrum and Signal Alignment Inc. ("ASSIA"). The patents relate, in general terms, to asymmetric digital subscriber line ("ADSL") technology. ADSL technology is used to send data over telephone lines, for example in providing broadband internet access to customers. The inventions are concerned with the ways in which those lines are managed. Both patents were alleged to be infringed by the defendant, British Telecommunications plc ("BT"), in its Dynamic Line Management System, which is responsible for controlling the operation of BT's broadband services. The first patent (in order of priority date) was European patent (UK) 2,259,495 ("495"). 495 was held by the judge to be valid, but not infringed by BT. The second patent was European patent (UK) 1,869,790 ("790"). 790 was held to be both valid and infringed. Both sides appeal with the judge's permission.
Although we still have a very large number of issues to deal with, the issues on this appeal are less extensive than they were before the judge. The judge was faced with three separate alleged infringements of the 495 patent: BT's 20CN, 21CN and NGA systems. Only the NGA system (NGA stands for "Next Generation Access") raises live issues before us. The judge also had to deal with multiple grounds of invalidity of both patents. Before us, there is no longer any attack on the validity of 790. On 495, there is no validity attack if the patent is construed narrowly, as the judge construed it. ASSIA accepts that if claim 1 is construed widely enough to cover the NGA system, then it is invalid. In those circumstances it relies instead on claim 6, which BT contends is both invalid and not infringed.
The case for BT on both appeals was presented by Mr Roger Wyand QC with Mr Hugo Cuddigan, and that for ASSIA by Mr Iain Purvis QC with Mr Joe Delaney. We heard the argument on 790 first, followed by 495, and I will approach the appeals in that order, after I have introduced some of the technical background, common to both actions.
Technical Background
As is the case with almost all patent cases in the field of telecommunications technology, it is necessary to negotiate some technical background in order to make sense of the issues which divide the parties.
Data is transmitted down telephone lines at a rate called the bit rate. In ADSL there are rates for upstream (away from the customer) and downstream (towards the customer) which are not the same – hence the description "asymmetric". In order to ensure that the data is received at the other end it must be transmitted with sufficient power relative to the noise on the channel, otherwise errors will occur in the received data. The signal to noise ratio (SNR) is used to measure the power of a signal as compared with noise. An SNR margin is used to specify a margin which the signal power must have above a minimum signal power for a specified error rate.
Various techniques exist to correct errors. The bit error rate (BER) is a measure of the uncorrected errors as a proportion of the total number of bits transferred per unit time.
Interleaving is a technique used to enhance error correction caused by bursts of errors in the transmitted data. Interleaving (for example by writing data into a buffer in rows and reading it out in columns) spreads out the errors, making them easier to correct. A drawback is that interleaving increases the delay between data transmission and the time when the decoded data is available: an effect known as latency.
From the foregoing it will be understood that there is a trade-off between the rate at which data can be sent down a telephone line and the number of errors. Higher speeds will give rise to a greater number of errors. A balance needs to be struck.
A typical ADSL system connects terminal equipment at a customer's premises, such as a home computer connected to a broadband router, to the central office or CO run by the network operator. Inside the broadband router is a modem which communicates via a channel to a second modem in the CO.
In order for the two modems to communicate successfully, they must have a shared communications protocol. To achieve this they automatically negotiate the appropriate values for certain parameters. This process is called initialisation. The experts used the term "transmission parameters" to describe the set of negotiated and mutually shared parameters needed to ensure successful communication between the modems. Following initialisation the modems start working normally to transmit data upstream and downstream in what is called SHOWTIME.
Another expression used in the evidence is "configuration parameters". These are the values given to the modems by the operator of the line, ahead of initialisation. These configuration parameters are not used directly by the modems during SHOWTIME but they set the boundaries or requirements that the operator wishes the modem pair to comply with in operation. An example of a configuration parameter specified by the DSL Management Standard is MAXNOMPSD.
At the priority date of both patents, any change to configuration parameters used in a particular DSL line was typically effected through a process of manual human evaluation and intervention at the central office.
The 790 patent
The specification of 790 is entitled "DSL state and line profile control". The invention is said to relate to managing line profiles in a DSL system. An example of a line profile is set out at [0003], identifying, amongst other things, maximum and minimum upstream and downstream data rates as controllable profile parameters. At [0004] it is explained that operators currently use these profiles in a simple manner to control only an individual line's data rate, and perhaps forward error correction margin. These were, therefore, often controlled manually, thereby causing that line to remain in the same profile until maintenance personnel intervened to set a new profile, perhaps in response to a customer request for a faster service. Even when a line is permitted to change profile automatically, only a few transitions are considered. Thus the specification explains at [0006] that:
"Systems, methods and techniques that permit implementation of a wide variety of line profiles and transitions between such profiles automatically and with ease in communication systems such as DSL systems would represent a significant advancement in the art. In particular, prioritization and implementation of transition options in the communication system would represent a considerable advancement in the field of DSL service rates and associated ranges."
Having thus set out its overall objective, the patent then sets out two aspects of the invention, along the lines of the independent claims. The claims refer to three concepts which are important: a "state transition matrix", "priority" and "feasibility". An understanding of these can be gleaned from the specification at [0043] to [0048]. The judge summarised them in this way:
"197. The patent uses two concepts which are key to the method of selecting profiles it discloses. These are priority and feasibility. Neither expression is a term of art and the skilled reader's understanding of them would come from reading the patent itself. Essentially the idea is that the system will extract out from a set of possible profiles which a line could adopt, a set of feasible profiles. That is a set of profiles which would provide acceptable operation of the line in the given circumstances. The set of possible profiles is divided into those which are feasible and those which are infeasible. This still presents a problem since the system has to have a means for selecting a particular profile to use from the group of profiles which are determined to be feasible. This is the point at which the priority concept plays a part. The possible profile transitions have an allocated priority which is independent of line conditions. It is an inherent property of each transition from a given profile to each target profile. The transition to a feasible profile with the highest priority is the one which is selected. The DSL line is then operated using this profile.
198. To carry out the method disclosed, the patent describes the use of a profile state transition matrix. The profile state transition matrix is a matrix which records the state transitions which are allowed and contains the priority of each possible transition. An example is matrix T in figure 4 as follows:
In this matrix each column relates to a given starting profile. So if the current profile for the DSL line in question is profile 1, the first column is the relevant column to use. If the current profile was profile 2, the...
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