Prior art

The full text of US patent 7940851 has been provided, fulfilling the request to search the USPTO database for this specific patent number. US7940851, titled "Radio communication apparatus and radio communication method," was filed on April 21, 2006, and published on May 10, 2011. Its stated objective is to reduce the amount of feedback information and system traffic in MIMO communication systems, particularly by addressing the problem of increasing Channel Quality Indicator (CQI) feedback overhead. This is achieved by generating feedback information from an absolute value of communication quality for a reference antenna and relative values for other antennas.

Based on the problem statement in US7940851, which focuses on reducing CQI feedback overhead in MIMO systems, especially for frequency scheduling, the most relevant prior art would be patents addressing efficient channel state information (CSI) or CQI feedback in multi-antenna communication systems. From the list of patent citations for US7940851, the following patents are identified as highly relevant: US6985536B2, US7180879B2, US20050180491A1, and US20060045203A1.

Here is an analysis of each:

---

Most Relevant Prior Art for US7940851:

1. US6985536B2

• Full Citation: US 6,985,536 B2, "Method and apparatus for efficient feedback in a wireless communication system" to Kyeong-Ahn OH, et al., assigned to LG Electronics Inc.
• Publication/Filing Date: Granted: January 10, 2006; Filed: February 28, 2002.
• Brief Description: This patent describes a method for a mobile station to efficiently feed back channel quality information (CQI) to a base station in a wireless communication system. The mobile station measures the channel quality of multiple sub-bands and transmits only the CQI values that meet a predetermined criterion. This aims to reduce the amount of feedback information by selectively reporting CQI.
• Potential Anticipation (35 U.S.C. § 102): US6985536B2 addresses the general problem of reducing feedback overhead for channel quality. However, it focuses on transmitting only selected CQI values (e.g., those meeting a criterion) rather than the specific approach of US7940851, which involves transmitting an absolute CQI for a reference antenna and relative CQI values for other antennas, specifically on a per-block (chunk) basis. Therefore, while it anticipates the need for efficient feedback, it does not appear to directly anticipate the specific structural and functional elements of Claim 1 of US7940851, particularly the calculation and transmission of relative CQI values with respect to a reference.

2. US7180879B2

• Full Citation: US 7,180,879 B2, "Communication apparatus and communication method for communicating channel state information" to Jian-Ming CHEN, assigned to Industrial Technology Research Institute.
• Publication/Filing Date: Granted: February 20, 2007; Filed: September 25, 2002.
• Brief Description: This patent describes an apparatus and method for communicating channel state information (CSI) in a wireless communication system. It involves a receiver generating CSI by analyzing a received signal and a transmitter sending data based on the CSI. The CSI is represented using a pre-coding matrix index (PMI) and a channel quality indicator (CQI) to provide efficient feedback for Multiple-Input Multiple-Output (MIMO) systems.
• Potential Anticipation (35 U.S.C. § 102): US7180879B2 pertains to communicating CSI (including CQI) in MIMO systems, which is the broad technical field of US7940851. However, its abstract indicates the use of PMI and CQI to represent CSI, without explicitly detailing a mechanism of combining an absolute CQI for a reference stream and relative CQI values for other streams per frequency block to reduce feedback overhead. Therefore, while it addresses CSI feedback in MIMO, it does not appear to directly anticipate the specific "absolute value and relative value" per-block CQI feedback mechanism described in Claim 1 of US7940851.

3. US20050180491A1

• Full Citation: US 2005/0180491 A1, "Method and apparatus for supporting MIMO transmission" to Jung-Je Son, assigned to [[Samsung Electronics Co.](/litigations/by-defendant/Samsung%20Electronics%20Co.), Ltd.](/litigations/by-plaintiff/Samsung%20Electronics%20Co.%2C%20Ltd.)
• Publication/Filing Date: Published: August 18, 2005; Filed: February 17, 2004.
• Brief Description: This patent application describes a method and apparatus for supporting MIMO transmission by transmitting channel information (including channel matrix and signal-to-noise ratio) from a receiver to a transmitter. The channel information is used by the transmitter to determine optimal transmission parameters, such as modulation and coding scheme.
• Potential Anticipation (35 U.S.C. § 102): US20050180491A1 generally describes feedback of channel information (which would include CQI) for MIMO transmission to select optimal transmission parameters. Similar to the other cited prior art, it establishes the general context of MIMO feedback. However, the abstract does not disclose the specific inventive step of US7940851, which is the calculation and transmission of an absolute CQI for a reference stream and relative CQI values for other streams, on a per-block basis, to explicitly reduce feedback overhead. Therefore, it may anticipate the broad concept of MIMO feedback but not the detailed mechanism claimed in US7940851.

4. US20060045203A1

• Full Citation: US 2006/0045203 A1, "Mobile communication system and mobile station apparatus" to Ryuji Umeki, assigned to Panasonic Corporation.
• Publication/Filing Date: Published: March 2, 2006; Filed: August 25, 2005.
• Brief Description: This patent application describes a mobile communication system and mobile station apparatus that improve throughput in a multi-carrier system by reporting channel quality indicators. The mobile station measures reception quality for each channel (sub-carrier or sub-band) and reports a representative CQI and differential CQIs for other channels, or it selects a particular channel and reports its absolute CQI and differential values for others.
• Potential Anticipation (35 U.S.C. § 102): This patent application is highly relevant as it explicitly mentions reporting a "representative CQI and differential CQIs for other channels" or "selecting a particular channel and reports its absolute CQI and differential values for others." This concept of sending an absolute value for one channel and differential (relative) values for others directly anticipates a core aspect of US7940851's Claim 1, which states "calculate a first absolute CQI value per each of the blocks for the first data and a second absolute CQI value per each of the blocks for the second data, and calculate a relative value of the second absolute CQI value with respect to the first absolute CQI value, per each of the blocks; and a transmitting unit configured to transmit the first absolute CQI value and the relative value of the second absolute CQI value in the same block." US20060045203A1, published before the filing date of US7940851, teaches the idea of combining absolute and differential (relative) CQI values to reduce feedback, potentially for different sub-bands (which are analogous to "blocks" or "chunks" in US7940851). It specifically addresses reducing feedback overhead in multi-carrier systems using this technique. This document appears to directly anticipate the method of reducing feedback by sending one absolute CQI and subsequent relative CQIs, as claimed in US7940851, particularly concerning the core inventive aspect of reducing overhead by combining absolute and relative channel quality information. Therefore, US20060045203A1 potentially anticipates Claim 1 and all claims dependent thereon in US7940851.