Microsoft Corp. v. Commonwealth Scientific & Industrial Research Organisation

572 F. Supp. 2d 786, 2008 U.S. Dist. LEXIS 62485, 2008 WL 3854561
CourtDistrict Court, E.D. Texas
DecidedAugust 14, 2008
Docket6:06 CV 549, 6:06 CV 550, 6:06 CV 551, 6:07 CV 204
StatusPublished
Cited by2 cases

This text of 572 F. Supp. 2d 786 (Microsoft Corp. v. Commonwealth Scientific & Industrial Research Organisation) is published on Counsel Stack Legal Research, covering District Court, E.D. Texas primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
Microsoft Corp. v. Commonwealth Scientific & Industrial Research Organisation, 572 F. Supp. 2d 786, 2008 U.S. Dist. LEXIS 62485, 2008 WL 3854561 (E.D. Tex. 2008).

Opinion

memorandum: opinion AND ORDER

LEONARD DAVIS, District Judge.

This Memorandum Opinion construes the disputed terms in U.S. Patent No. 5,487,069 (the “'069 Patent”). Also before the Court is Defendants’ 1 Motion for Summary Judgment of Invalidity. 2 The Court DENIES Defendants’ motion for the reasons below.

BACKGROUND

The '069 Patent relates to a wireless Local Area Network (“WLAN”) wherein a plurality of wireless transceivers communicate with a plurality of wireless hub transceivers. Radio frequency wave propagation characteristics must be considered in implementing a WLAN. Radio waves can be reflected by some materials such as walls, furniture, and other indoor items, creating “multipath” where a radio signal is dispersed and arrives at the receiver from different paths. As a result, there can be multiple copies of the signal with different signal strengths. The problem that can result is called “intersymbol interference” (“ISI”), which is an overlap in arrival of the same symbol from different paths. ISI is the result of time differences between the arrivals of reflected copies of the same signal. This time difference is referred to as “delay spread.” As the data transmission speed gets faster, the time duration of the transmitted symbols (symbol period) gets smaller and more susceptible to ISI. In conventional radio transmission, the symbol period is set to be longer than the delay spread. Thus, multipath places an upper limit on data transmission rate. That is, as the delay spread increases, the symbol period must get longer, which in turn means that the data transmission rate necessarily decreases.

The '069 Patent provides high data transfer rates and high reliability in wireless environments with significant multi-path interferrence. The patent teaches a combination of three key techniques: parallel sub-channels (ensemble modulation) wherein the period of a sub-channel symbol is longer than a predetermined time delay of the non-direct transmission paths, data reliability enhancement through Forward Error Correction (“FEC”), and data reliability enhancement through bit interleaving.

Radio transmission of information relies upon the concept of superimposing information on, or “modulating,” a carrier wave. In conventional radio transmission, the carrier is at a specific “narrowband” frequency. The receiver must be tuned to that same narrowband frequency to receive the transmission. If there are many transmissions occurring at the same time at the narrowband frequency, interference will result. In order to minimize interference, various techniques have been developed.

One technique to avoid interference from other transmission sources is to spread the signal over a wider range of frequencies. This is referred to as “spread spectrum.” A particular approach to the reduction of interference is Fre *792 quency Hopping Spread Spectrum (“FHSS”), where the signal carrier is transmitted for a short period of time (“dwell time”) on one narrowband frequency and is then hopped to another narrow-band frequency. A WLAN that uses FHSS to reduce interference with other devices operates on a predetermined hopping sequence that is known to the receiver and can be followed by it. The dwell time, however, must be consistent with the delay spread to avoid ISI. Thus, FHSS is a wideband modulation scheme that uses multiple carriers one at a time and avoids interference with other transmission signals in the same band by hopping over many different frequencies. During any one hop, the FHSS signal appears to be a narrowband signal.

Another technique is to use multiple carriers simultaneously rather than one at a time. This is technically not a spread spectrum because the carriers remain stationary and are not moved, but it serves the same purpose of spreading the signal power over a large band. This is known as Orthogonal Frequency Division Multiplexing (“OFDM”) or Multicarrier Modulation (“MCM”). The data is broken into subparts and each subpart is simultaneously transmitted on a different carrier frequency. Again, the transmission period of each part (the sub-channel symbol period) must be consistent with the delay spread to avoid ISI. As there is simultaneous transmission of all the signal parts, the data transmission rate is higher than with FHSS.

In addition to various modulation schemes for radio frequency transmission of data, an important aspect of WLAN data transmission is the addition of data reliability enhancement afforded by using coding of the actual data prior to its conversion to a modulated transmission signal. Forward Error Correction (“FEC”) coding is one type of digital signal processing that improves data reliability by introducing a known structure into a data sequence prior to transmission. This structure allows a receiver to detect and possibly correct errors caused by corruption from the channel without requesting re-transmission of the original information. In a system that employs FEC, a digital information source sends a data sequence to an encoder. The encoder inserts redundant bits, thereby outputting a longer sequence of code output bits as a “codeword.” One type of FEC is known as “convolutional coding.” The incoming data is in a stream of bits. A Rate /& convolutional encoder provides two data “di-bits” for every input bit.

Additional protection to data corruption due to adjacent burst errors is data “interleaving,” which spreads data over a variable period of time. With data interleaving, data is transmitted by spacing the content of consecutive data packets. Interleaving is used in conjunction with FEC. Burst errors are distributed over many data packets and the FEC has fewer errors to correct in each packet. Data interleaving shuffles the data to reduce the error rate.

In February, 2005, Commonwealth Scientific & Industrial Research Organisation (“CSIRO”) sued Buffalo Technology (USA) and Buffalo, Inc. (collectively, “Buffalo”) for infringement of the '069 Patent (the “Buffalo ” litigation). The parties disputed multiple claim terms, and the Court issued a claim construction opinion. Commonwealth Scientific & Indus. Research Org. v. Buffalo Tech. (USA), Case No. 6:06cv324, 2006 WL 1233122, at * 9 (E.D.Tex. May 8, 2006) (Davis, J.) (“Buffalo Claim Construction Opinion”). The Court subsequently granted summary judgment on validity and infringement. Commonwealth Scientific & Indus. Research Org. v. Buffalo Tech. (USA), Case No. 6:06cv324, 2006 WL 3317080, at * 15 *793 (E.D.Tex. Nov.13, 2006) (Davis, J.) (“Bufalo Summary Judgment Order").

After commencement of Buffalo, a flurry of litigation between CSIRO and Defendants ensued, and CSIRO alleges Defendants infringe various claims of the '069 Patent. CSIRO and Defendants agree with the Court’s construction of claim terms in Buffalo except for those terms the parties dispute in the instant litigation. Transcript of Claim Construction Hearing held on 6/26/2008, 14-15. The Court fully incorporates its previous claim construction opinions into this opinion. 3

APPLICABLE LAW

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572 F. Supp. 2d 786, 2008 U.S. Dist. LEXIS 62485, 2008 WL 3854561, Counsel Stack Legal Research, https://law.counselstack.com/opinion/microsoft-corp-v-commonwealth-scientific-industrial-research-txed-2008.