DCT
1:22-cv-06660
Swirlate IP LLC v. RAB Lighting Inc
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Swirlate IP LLC (Texas)
- Defendant: RAB Lighting Inc. (Illinois)
- Plaintiff’s Counsel: Direction IP Law
- Case Identification: 1:22-cv-06660, N.D. Ill., 11/29/2022
- Venue Allegations: Venue is alleged to be proper based on Defendant maintaining a regular and established place of business within the Northern District of Illinois, from which it has purportedly committed acts of infringement.
- Core Dispute: Plaintiff alleges that Defendant’s RAB Lightcloud Gateway 4G infringes two patents related to methods for improving wireless data transmission reliability using constellation rearrangement in Automatic Repeat reQuest (ARQ) diversity schemes.
- Technical Context: The technology addresses improving the integrity of data sent over unreliable wireless channels, such as LTE networks, by systematically altering the bit-to-symbol mapping during retransmissions to average out error rates.
- Key Procedural History: The complaint notes that U.S. Patent No. 7,567,622 is a continuation of the application that led to U.S. Patent No. 7,154,961, and the two patents share an identical specification. During prosecution of the '622 patent, the applicant distinguished the invention from prior art by arguing that retransmission is employed only when an initial transmission fails, thereby reducing overall data traffic.
Case Timeline
| Date | Event |
|---|---|
| 2002-10-18 | Priority Date for ’961 and ’622 Patents |
| 2006-12-26 | Issue Date for U.S. Patent 7,154,961 |
| 2009-07-28 | Issue Date for U.S. Patent 7,567,622 |
| 2018-10-18 | Date of a technical article on HARQ referenced in the complaint |
| 2022-11-29 | Complaint Filing Date |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 7,154,961 - "Constellation Rearrangement for ARQ Transmit Diversity Schemes," issued December 26, 2006
The Invention Explained
- Problem Addressed: In wireless communication systems using higher-order modulation formats (e.g., 16-QAM), where more than two bits are mapped onto a single transmission symbol, the individual bits possess different levels of reliability depending on the specific mapping used. This can lead to degraded decoder performance when retransmissions are combined at the receiver. (’961 Patent, col. 2:1-7; Compl. ¶14).
- The Patented Solution: The invention proposes improving performance at the receiver by applying different signal constellation mappings for transmissions sent over different diversity branches or during successive ARQ retransmissions. By altering the bit-to-symbol mapping for the same set of data bits, the reliability levels of the individual bits are effectively averaged across the multiple transmissions, leading to more robust decoding. (’961 Patent, col. 2:20-29; Compl. ¶15).
- Technical Importance: This technique provides a method to enhance the reliability of data transmission over time-varying and unreliable channels, which is a foundational challenge in mobile and wireless networking. (Compl. ¶11).
Key Claims at a Glance
- The complaint asserts at least independent claim 1. (Compl. ¶16).
- Essential elements of claim 1 include:
- An ARQ re-transmission method in a wireless communication system.
- Modulating data packets using a first modulation scheme to obtain first data symbols.
- Transmitting the first data symbols over a first diversity branch.
- Modulating the same data packets using a second modulation scheme to obtain second data symbols.
- Transmitting the second data symbols over a second diversity branch.
- Demodulating the received symbols using the respective first and second modulation schemes.
- Diversity combining the demodulated data.
- A specific requirement that the modulation schemes are 16 QAM and a number of log2(M) modulation schemes are used.
U.S. Patent No. 7,567,622 - "Constellation Rearrangement for ARQ Transmit Diversity Schemes," issued July 28, 2009
The Invention Explained
- Problem Addressed: The '622 patent shares its specification with the ’961 patent and thus addresses the identical technical problem of unequal bit reliabilities in higher-order modulation schemes degrading decoder performance. (’622 Patent, col. 2:5-11; Compl. ¶28).
- The Patented Solution: The patented solution is also to use different signal constellation "mappings" for an initial transmission and a subsequent retransmission of the same data. During prosecution, the applicant emphasized that this retransmission occurs only upon request after a failed initial transmission, thereby reducing overall data traffic compared to prior art systems that always transmitted redundant data. (’622 Patent, col. 2:15-24; Compl. ¶¶29-30).
- Technical Importance: The invention offers a more efficient approach to achieving transmission diversity and reliability, conserving network resources by invoking retransmission with a different mapping only when necessary. (Compl. ¶30).
Key Claims at a Glance
- The complaint asserts at least independent claim 1. (Compl. ¶31).
- Essential elements of claim 1 include:
- An ARQ re-transmission method using a higher order modulation scheme where more than two data bits are mapped to one symbol.
- Modulating data packets using a first mapping of the scheme to get first data symbols.
- Performing the first transmission.
- Receiving a repeat request at the transmitter.
- In response to the request, modulating the packets using a second mapping of the scheme to get second data symbols.
- In response to the request, performing the second transmission.
- A requirement that the first and second mappings are pre-stored in a memory table.
III. The Accused Instrumentality
Product Identification
The RAB Lightcloud Gateway 4G ("Accused Instrumentality"). (Compl. ¶16).
Functionality and Market Context
The Accused Instrumentality is a communications hub for lighting systems, connecting local "Lightcloud" devices to a cloud-based management service via a 4G LTE cellular connection. (Compl. p. 6). The infringement allegations center on the device's use of the LTE network's standard Hybrid Automatic Repeat Request (HARQ) protocol to ensure reliable data transmission between the gateway and the cellular base station. (Compl. ¶17). The complaint alleges the device uses modulation schemes including 16-QAM and 64-QAM and implements "Adaptive Re-transmission," where the Modulation and Coding Scheme (MCS) can be changed for retransmissions. (Compl. ¶¶18, 20). The complaint includes a product image and feature list for the gateway. A screenshot from a product webpage describes the "LCGATEWAY/4G/VZ" as connecting to a cloud service using a "secure cellular 4G connection." (Compl. p. 6).
IV. Analysis of Infringement Allegations
'961 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| an ARQ re-transmission method in a wireless communication system wherein data packets are transmitted from a transmitter to a receiver using a first transmission and at least a second transmission based on a repeat request | The Accused Instrumentality uses a HARQ method in an LTE network to transmit data packets from the gateway to an LTE base station, with retransmissions based on repeat requests (NAK). | ¶17 | col. 9:8-14 |
| modulating data packets at the transmitter using a first modulation scheme to obtain first data symbols | The Accused Instrumentality modulates data packets using a first modulation scheme (e.g., QPSK, 16QAM, 64QAM) decided by a MAC Scheduler. A diagram from an ETSI standard illustrates the "Data modulation" block. (Compl. p. 9). | ¶18 | col. 9:15-17 |
| performing the first transmission by transmitting the first data symbols over a first diversity branch to the receiver | First data symbols are transmitted over a first diversity branch using multi-antenna processing. | ¶19 | col. 9:18-21 |
| modulating said data packets at the transmitter using a second modulation scheme to obtain second data symbols | Upon receiving a repeat request, the device uses a second, distinct modulation scheme via "Adaptive Re-transmission," which changes the Modulation Coding Scheme (MCS). A diagram from a technical website illustrates this adaptive process. (Compl. p. 15). | ¶20 | col. 9:22-24 |
| performing the second transmission by transmitting the second data symbols over a second diversity branch to the receiver | Second data symbols are transmitted over a second diversity branch, indicated by multi-antenna processing where signals are mapped to different antenna ports. | ¶21 | col. 9:25-28 |
| diversity combining the demodulated data received over the first and second diversity branches | The LTE base station performs "Hybrid ARQ soft-combining" on data received from multiple diversity branches (antenna ports). | ¶23 | col. 9:32-35 |
| wherein: the modulation schemes are 16 QAM and a number of log2 (M) modulation schemes are used | The Accused Instrumentality allegedly uses 16-QAM and 64-QAM, which are log2(M) modulation schemes. | ¶24 | col. 9:36-39 |
'622 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| An ARQ re-transmission method...using a higher order modulation scheme wherein more than two data bits are mapped onto one data symbol | The Accused Instrumentality uses higher-order modulation schemes like 16-QAM (4 bits/symbol) and 64-QAM (6 bits/symbol). A table from a technical article shows the bits per symbol for these schemes. (Compl. p. 40). | ¶32 | col. 7:42-47 |
| modulating data packets...using a first mapping of said higher order modulation scheme to obtain first data symbols | The device uses a first mapping (e.g., a specific QAM scheme) to create first data symbols for the initial transmission. | ¶33 | col. 7:48-51 |
| receiving at the transmitter the repeat request issued by the receiver to retransmit... | The transmitter (Accused Instrumentality) receives a HARQ retransmission request (NAK) from the receiver (LTE base station) if the first transmission is not successfully decoded. | ¶35 | col. 7:54-58 |
| modulating, in response to the received repeat request...using a second mapping of said higher order modulation scheme to obtain second data symbols | In response to a NAK, the device performs "Adaptive Re-transmission" using a second mapping with a different Modulation Coding Scheme (MCS) than the first transmission. | ¶36 | col. 7:59-63 |
| wherein the first and second mapping of said higher order modulation schemes are pre-stored in a memory table | The modulation schemes are decided by a MAC Scheduler, and the complaint alleges the mappings are pre-stored in a memory table at the receiver. A diagram from an ETSI standard is annotated to show a "Pre-stored in a memory table" pointing to the Data Modulation block. (Compl. p. 68). | ¶40 | col. 8:1-4 |
- Identified Points of Contention:
- Technical Scope Question: The infringement theory relies heavily on the assertion that a standard-compliant LTE "Adaptive Re-transmission," which involves changing the Modulation and Coding Scheme (MCS), is equivalent to the "second modulation scheme" or "second mapping" required by the patents. A central question for the court will be whether a change in MCS inherently performs the specific constellation rearrangement (e.g., bit re-ordering or inversion) taught in the patent specifications for averaging bit reliabilities, or if there is a technical distinction.
- Evidentiary Question: The complaint's evidence consists almost entirely of general descriptions of LTE HARQ functionality from public standards documents (ETSI) and third-party technical websites, rather than specific analysis of the Accused Instrumentality itself. This raises the question of whether the complaint provides sufficient factual support to demonstrate that the accused gateway specifically implements these features in an infringing manner.
- Claim Scope Question ('622 Patent): Claim 1 of the '622 Patent requires that the first and second "mappings" are "pre-stored in a memory table." The complaint alleges this is satisfied by a MAC Scheduler determining the scheme. The defense may argue that a dynamic scheduling decision does not meet the "pre-stored in a memory table" limitation, which could be construed to imply a more static lookup function.
V. Key Claim Terms for Construction
The Term: "second modulation scheme" ('961 Patent) / "second mapping of said higher order modulation scheme" ('622 Patent)
Context and Importance: The core of the alleged invention is using a different scheme or mapping for a retransmission. The entire infringement case hinges on whether the accused device's change in MCS for adaptive retransmission qualifies as a "second" and "distinct" scheme/mapping under the patents' claims.
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The claims themselves do not specify the type of difference required, only that the second scheme/mapping is different from the first. Plaintiff may argue that any change that alters the bit-to-symbol relationship, such as a change in MCS, falls within the plain meaning of the term.
- Evidence for a Narrower Interpretation: The specification provides specific examples of creating a different mapping, such as exchanging the positions of bits (e.g.,
i1q1i2q2becomesi2q2i1q1) or inverting bit values (’961 Patent, col. 12:1-15). A defendant may argue these examples limit the claim scope to such explicit constellation rearrangements, and a standard MCS change does not necessarily perform this function.
The Term: "diversity branch" ('961 Patent, '622 Patent)
Context and Importance: The claims require transmissions over first and second diversity branches. The complaint alleges this is met through multi-antenna processing.
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specification explicitly lists "Antenna Diversity" where the signal originates from different antennas as a known form of transmit diversity (’961 Patent, col. 1:30-33). This provides strong intrinsic support for construing "diversity branch" to include distinct spatial paths created by multiple antennas.
- Evidence for a Narrower Interpretation: While a narrow interpretation seems less likely given the specification, a party could argue that the term should be understood in the full context of the invention, which focuses on averaging bit reliabilities. However, the explicit mention of antenna diversity in the background makes this a challenging position.
VI. Other Allegations
No indirect or willful infringement is alleged in the complaint.
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of technical equivalence: Does the accused gateway’s alleged use of standard LTE "Adaptive Re-transmission," which changes the Modulation and Coding Scheme (MCS), perform the specific function of constellation rearrangement taught by the patents to average bit reliabilities, or is there a fundamental mismatch in the technical operation?
- The case will also turn on a question of claim construction: Can the terms "second modulation scheme" and "second mapping" be interpreted broadly to read on any change in MCS, or are they limited by the specification's examples to a more specific bit-level reordering or inversion within the symbol constellation?
- Finally, a key evidentiary question will be whether the Plaintiff can successfully link its infringement theory, which is based on general technical standards, to the specific, actual operation of the Defendant's product.