US 8090008

US Patent 8,090,008 — Summary

Bibliographic Data

The patent is a continuation chain: 12/255,713 → 11/863,581 → 11/211,535 → 09/710,310 (U.S. 6,961,369) → Provisional 60/164,134.

Abstract (verbatim)

A system and method that scrambles the phase characteristic of a carrier signal are described. The scrambling of the phase characteristic of each carrier signal includes associating a value with each carrier signal and computing a phase shift for each carrier signal based on the value associated with that carrier signal. The value is determined independently of any input bit value carried by that carrier signal. The phase shift computed for each carrier signal is combined with the phase characteristic of that carrier signal so as to substantially scramble the phase characteristic of the carrier signals. Bits of an input signal are modulated onto the carrier signals having the substantially scrambled phase characteristic to produce a transmission signal with a reduced PAR.

Technology Overview

The patent addresses peak-to-average power ratio (PAR) in multicarrier (DMT/OFDM) systems. Instead of relying only on bit-level scrambling to randomize signal phases, the invention deterministically applies per-carrier phase shifts computed from values (e.g., from a pseudo-random number generator, carrier number, symbol count, superframe/hyperframe count) that are independent of the data bits carried by each carrier. Both ends know the values (independently derived or communicated), so the receiver can descramble. It also discloses a clipping-avoidance scheme where a predefined non-data signal is substituted when a DMT symbol would clip, and the symbol is retried with different time-varying phase shifts. The specification gives example phase-shift formulas (e.g., N×π/3 mod 2π; (N+M)×π/4 mod 2π; X_N×π/6 mod 2π).

Independent Claims — Plain-Language Overview

The patent has 26 claims: independent Claim 1 (method) and independent Claim 14 (system); claims 2–13 and 15–26 are dependent.

Claim 1 (method). A method in a multicarrier transceiver for scrambling carrier phases where each carrier's phase is tied to the bit stream: (a) assign each carrier a value generated by a pseudo-random number generator, where the value is determined independently of the bit value that carrier carries; (b) compute a phase shift per carrier from that value; and (c) combine each carrier's phase shift with its phase characteristic to substantially scramble the carriers' phases — with the added requirement that multiple carrier signals are used to modulate the same bit value.

Claim 14 (system). A multicarrier system with a first transceiver capable of performing the same three functions as Claim 1 (PRNG-based, bit-independent per-carrier values; per-carrier phase-shift computation; combination to substantially scramble the phases), again requiring that multiple scrambled carriers modulate the same bit value.

Dependent claims (2–13, 15–26) add limitations including: transceiver is a cable transceiver or VDSL transceiver; bit stream transports video or high-speed Internet access; a second transceiver independently derives values using its own PRNG; first and second transceivers share the same PRNG seed; transceivers are wireless, cable, or DSL transceivers connected over twisted pair; second transceiver is a VDSL transceiver.

Litigation / Docket Notes

• CAFC 2026 (relevant to this patent): TQ Delta, LLC v. CommScope Holding Company, Inc., Appeal Nos. 2024-1587 (lead) and 2024-1588 (cross-appeal), consolidated Apr. 8, 2024, from E.D. Tex. No. 2:21-cv-00310-JRG (related case 2:21-cv-00309). On April 24, 2026, the Federal Circuit issued a nonprecedential opinion affirming, per the Fed Circuit Blog: TQ Delta appealed the denial of JMOL/new trial on the jury's noninfringement finding for the '008 patent, the district court's claim construction affecting invalidity of U.S. 8,462,835, and the denial of a new trial on damages — all affirmed.
• Claim constructions from that litigation: "phase characteristic(s)" = "one or more values that represent the angular aspect of a constellation point"; "substantially scramble the phase characteristics of the plurality of carrier signals" = "adjust the phase characteristics of the carrier signals by varying amounts to produce a transmission signal with a reduced peak-to-average power ratio (PAR)."
• PTAB: IPR2015-00240 (2Wire, Inc. v. TQ Delta LLC, filed Nov. 7, 2014) — institution denied May 29, 2015.
• Other district-court cases involving the patent include Delaware actions (1:13-cv-01835, 1:13-cv-01836, 1:14-cv-00954, 1:15-cv-00121) and an Alabama N.D. case (5:14-cv-01381).

Uncertainty Notes

• The "adjusted expiration" date (Feb. 23, 2021) and "Expired - Fee Related" status come from Google Patents metadata and were not independently re-verified against USPTO PAIR in this search; treat them as approximate.
• The April 24, 2026 CAFC outcome is confirmed by the Fed Circuit Blog and the CAFC opinions/orders page for 24-1587 (nonprecedential, decided 04/24/2026); I did not retrieve the full opinion text, so the description of issues relies on the blog summary and docket entries.