Obviousness

Under 35 U.S.C. § 103, a patent claim is obvious if the differences between the claimed invention and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art (PHOSITA). The patent US8102833B2, with a priority date of September 13, 2007, aims to provide a method for transmitting uplink signals, including ACK/NACK signals, other control signals, and data signals, by efficiently arranging them in a resource region considering their priority, particularly by placing high-priority ACK/NACK signals near reference signals for improved reliability.

Core Invention of US8102833B2 (Claim 1):
Claim 1 describes a method for transmitting uplink signals in a wireless communication system, comprising:
(a) Serially multiplexing first control signals (not ACK/NACK) and data signals in a mobile station, with the first control signals placed at the front part and data signals at the rear part of the multiplexed signals.
(b) Mapping these multiplexed signals to a 2-dimensional (2D) resource matrix where columns correspond to SC-FDMA symbols and rows to subcarriers. The columns exclude specific SC-FDMA symbols used for a reference signal, and the mapping follows a time-first method (e.g., across rows sequentially).
(c) Mapping ACK/NACK control signals to specific columns of the 2D resource matrix, where these columns are right adjacent to the reference signal SC-FDMA symbols. The ACK/NACK signals overwrite some of the multiplexed signals from step (b), starting from the last row of these specific columns.
(d) Transmitting the resulting mapped signals column by column to a base station.

Identified Prior Art References:
The following prior art references, all having priority dates earlier than US8102833B2, are relevant:

1. EP1806867A2 ([Samsung Electronics Co.](/litigations/by-defendant/Samsung%20Electronics%20Co.),Ltd.): "Method and apparatus for time multiplexing uplink data and uplink signaling information in a SC-FDMA system."
2. EP1811701A2 (Samsung Electronics Co., Ltd.): "Method and apparatus for transmitting/receiving uplink signaling information in a single carrier FDMA system."
3. US20080304467A1 (Samsung Electronics Co., Ltd.): "Control and data signaling in sc-fdma communication systems."
4. US20050286402A1 (Samsung Electronics Co., Ltd.): "Method and apparatus for transmitting uplink acknowledgement information in an OFDMA communication system."
5. US20030185159A1 (Samsung Electronics Co., Ltd.): "Apparatus and method for determining pilot signal field position information for uplink power control in an HSDPA mobile communication system."

Combination of Prior Art and Rationale for Obviousness:

A PHOSITA in mobile communication technology would have been motivated to combine these references to achieve a reliable and efficient uplink signal transmission method, addressing the problem of prioritizing critical ACK/NACK signals in resource allocation.

1. Foundation for SC-FDMA Uplink Transmission (Elements 1a, 1b.i, 1b.iii, 1d):

   • EP1806867A2 discloses a method for "time multiplexing uplink data and uplink signaling information in a SC-FDMA system," thereby providing the basic framework for multiplexing data and control signals for uplink transmission in an SC-FDMA system.
   • EP1811701A2 teaches mapping uplink signaling information to resource elements in a subframe using a "time-first mapping scheme." [cite: 8, Paragraph] This reference establishes the use of a 2D resource matrix with columns corresponding to SC-FDMA symbols and rows to subcarriers, and the application of time-first mapping. This addresses the mapping technique (1b.i, 1b.iii) and the concept of multiplexing (1a). The specific ordering of "first control signals placed at a front part... and data signals at a rear part" (1a) is a routine engineering choice for serial multiplexing, aiming for efficient packing or simplified processing, which a PHOSITA would readily implement.
   • The transmission "by column by column" (1d) is inherent to SC-FDMA symbol transmission, where each column represents an SC-FDMA symbol transmitted over time. EP1811701A2 describes transmitting uplink signaling information.

2. Exclusion of Reference Signal Symbols (Element 1b.ii):

   • The concept of reserving specific symbols for reference signals (pilot signals) for channel estimation and excluding them from data/control mapping regions is well-known in wireless communication systems. US20030185159A1, for instance, discusses "pilot signal field position information," indicating the understanding of dedicated resources for reference signals. Therefore, excluding these specific SC-FDMA symbols from the data/control mapping for other information would be a common design practice for a PHOSITA.

3. Prioritization and Placement of ACK/NACK Signals (Elements 1c.i, 1c.ii, 1c.iii):

   • US20080304467A1 explicitly teaches that "the control information is mapped to a region adjacent to a reference signal" to "improve channel estimation performance." [cite: 10, Paragraph] This reference provides a clear motivation for placing control signals near reference signals to enhance their reliability.
   • US20050286402A1 discloses methods for "transmitting uplink acknowledgement (ACK/NACK) information" by mapping it to an allocated resource region.
   • The background of US8102833B2 itself acknowledges that the 3GPP LTE system "prescribes that data signals and control signals among the uplink signals are first multiplexed and ACK/NACK signals are transmitted to the multiplexed signals by puncturing the data or control signals." This establishes the technique of puncturing for high-priority ACK/NACK signals as known prior art. [cite: "3GPP LTE system...ACK/NACK signals are transmitted to the multiplexed signals by puncturing the data or control signals when uplink ACK/NACK signal transmission is required for downlink data."]
   • The problem identified in US8102833B2 is that ACK/NACK, despite needing higher reliability than other control signals, could not be efficiently placed near reference signals if other control signals already occupied those spots. Given the teaching from US20080304467A1 to place control near reference signals for reliability, and the high priority of ACK/NACK signals (as noted in US8102833B2), a PHOSITA would be motivated to prioritize ACK/NACK placement in these advantageous locations. Consequently, mapping ACK/NACK signals to "specific columns... right adjacent" to the reference signal symbols (1c.i) is a direct and obvious application of the "adjacent" teaching to the highest priority control signal. Implementing this by "overwriting some of the multiplexed signals" (1c.ii) using the known puncturing technique would also be obvious. The specific detail of overwriting "from the last row of the specific columns" (1c.iii) is a routine design choice for a PHOSITA to systematically manage resource allocation when puncturing within a structured 2D time-first mapped resource grid. Different strategies for ordering punctured bits exist, and starting from the last row is a straightforward, non-inventive implementation decision.

Conclusion:
Therefore, the combination of EP1806867A2, EP1811701A2, US20080304467A1, US20050286402A1, and US20030185159A1, along with common general knowledge in 3GPP LTE systems regarding signal prioritization and resource management, would have rendered Claim 1 of US8102833B2 obvious to a PHOSITA. The motivation to combine these references stems from the clear need to ensure highly reliable transmission of critical ACK/NACK feedback within the constraints of SC-FDMA uplink resource allocation, a problem explicitly recognized and addressed by the combined prior art.