Obviousness

An analysis of the prior art cited in US patent 6,604,216 indicates that the claims would likely be considered obvious under 35 U.S.C. § 103 to a person having ordinary skill in the art (POSITA) at the time of the invention (circa 1999-2000). The core invention—adapting an Incremental Redundancy (IR) scheme to work with variable-rate channels by creating a single reordered sequence of bits from a mother code—represents an obvious combination of known techniques to solve a well-understood problem.

Person Having Ordinary Skill in the Art (POSITA)

A POSITA in the field of wireless communications around 1999 would have a graduate degree in electrical engineering or a related field, with practical experience in the design and implementation of digital communication systems, particularly error control coding and link-level protocols for mobile networks like GSM/GPRS. This individual would be familiar with concepts such as Forward Error Correction (FEC), Automatic Repeat-Request (ARQ), convolutional codes, and techniques like puncturing to achieve different code rates.

Obviousness Analysis of Independent Claims 1, 11, 19, and 30

These claims form the core of the invention and describe a transmitter, method, and system for sending variable-length "subsequences" of a "reordered mother code word" to fill the "available bandwidth of an available gross rate channel."

Proposed Combination of References:

1. J. Hagenauer, “Rate-Compatible Punctured Convolutional Codes (RCPC Codes) and their Applications”, IEEE Trans. Comm., vol. 36, no. 4, April 1988 (Hagenauer)
2. US 5,940,439 to Kleider et al. (Motorola '439)

Reasoning:

1. Hagenauer Teaches the Foundation of Incremental Redundancy: Hagenauer is a foundational text on creating flexible error correction schemes. It explicitly teaches the core components used in the '216 patent:

   • Starting with a single low-rate "mother code."
   • Applying different "puncturing patterns" to this mother code to generate blocks of parity bits with varying levels of redundancy.
   • Combining these blocks at the receiver to improve the chances of a successful decode.
     This directly teaches the concept of generating incremental redundancy information from a single encoded block, which is the basis for the "mother code word" in the '216 patent.

2. Motorola '439 Teaches Adapting Transmission Rate to Channel Conditions: The Motorola '439 patent addresses the well-known need to adapt a communication system's data rate to changing channel quality. It discloses a system that:

   • Determines the quality of the communication channel.
   • Selects a transmission format from a plurality of available formats based on this quality. The format can vary in code rate, modulation type, or both.
   • Transmits data using the selected format.
     This teaches the essential concept of "available gross rate channels" described in the '216 patent. A channel with better quality can support a higher gross rate (more bits per unit of time), while a channel with poor quality requires a lower rate. Motorola '439 explicitly links channel quality to the selection of a code rate, which dictates how many coded bits are sent for a given block of information.

3. Motivation to Combine Hagenauer and Motorola '439:
   A POSITA in 1999, faced with designing a data service for a wireless system like GPRS/EDGE, would be aware of both the efficiency of IR (from Hagenauer) and the necessity of Link Adaptation (from Motorola '439 or similar art). The problem, as noted in the '216 patent's own background section (Col. 4, ll. 4-13), was that existing IR schemes used fixed-size blocks, making them inefficient for the variable-rate channels inherent in an adaptive system.

   The motivation to combine these teachings would be to create a more efficient and flexible system. A POSITA would recognize that the fixed-block approach was suboptimal and would seek a way to apply the principle of IR (sending more parity bits as needed) to a system where the "container" for those bits (the available channel bandwidth for a given transmission time interval) varies in size.

4. The "Reordering Vector" as an Obvious Implementation Detail:
   The key inventive step claimed in the '216 patent is the use of a "reordering circuit" and an "ordering vector" to create a single, long sequence of bits from the mother code, from which variable-length subsequences can be drawn. This, however, is an obvious implementation of the combined Hagenauer and Motorola '439 principles.

   • Hagenauer teaches generating multiple sets of parity bits using different puncturing patterns.
   • To adapt this to a variable-rate channel, a POSITA would need a method to select the "next best" bits to send.
   • The most straightforward way to do this is to define a priority order for all the available parity bits. The '216 patent's method of creating an ordering vector by concatenating the bit positions from different puncturing patterns (e.g., O=[1,4,7,...,2,5,8,...], Col. 8, ll. 1-2) is a simple and logical way to establish such a priority.
   • Treating the available redundancy bits as a single stream or "pool" from which to draw as many bits as will fit in the channel is a direct and obvious solution to the problem of matching the IR scheme to the variable channel.

Therefore, a POSITA would have been motivated to combine the IR mechanism of Hagenauer with the adaptive rate principles of Motorola '439, and the use of a prioritized "ordering vector" to serialize the redundancy bits would have been an obvious design choice to implement this combination. This renders the inventions of claims 1, 11, 19, and 30 obvious.

Obviousness Analysis of Independent Claim 34

This claim is slightly different, describing a transmitter that uses the reordering scheme to transmit a subsequence over a "fixed net rate channel" to achieve a "desired code rate" based on a "quality of service requirement."

Proposed Combination of References:

1. Hagenauer
2. General knowledge of Link Adaptation (LA), as exemplified by the inventors' own prior art publication: Eriksson et al., "Comparison of Link Quality Control Strategies for Packet Data Services in EDGE," 1999 IEEE.

Reasoning:

Claim 34 describes the classic Link Adaptation (LA) problem, where the system chooses a specific code rate (a "fixed net rate") based on system requirements (QoS, channel quality) rather than simply filling available bandwidth.

1. Hagenauer Teaches the Mechanism: As before, Hagenauer provides the underlying mechanism for achieving arbitrary code rates by puncturing a single mother code.
2. LA Teaches the Goal: The principle of LA was well-established by 1999. The Eriksson paper, co-authored by the inventors of the '216 patent, is a clear example of prior art that discusses selecting modulation and coding schemes (MCS) to meet performance targets. This is precisely what claim 34 describes.
3. Motivation to Combine: The motivation is to implement LA in a more flexible manner. Instead of defining a discrete and limited set of puncturing patterns for a few specific code rates (e.g., CS-1 to CS-4 in GPRS), a POSITA would find it obvious to use the stream-based approach derived from Hagenauer to generate any desired code rate. The "bit ordering scheme" of the '216 patent becomes a tool to flexibly select the exact number of bits from the reordered mother code word needed to achieve the target code rate determined by the LA algorithm.

This combination of a known mechanism (RCPC from Hagenauer) with a known goal (flexible LA) renders the invention of claim 34 obvious. The claimed method is simply a more granular and flexible implementation of established principles.