Prior art

To identify the most relevant prior art for US patent 8891347, I will examine the "References Cited" section of the patent document itself. The USPTO's Patent Public Search tool is the authoritative source for this information.

Based on the provided patent text, here are some of the "References Cited" listed under "OTHER PUBLICATIONS":

Cited Prior Art for US8891347:

1. Written Opinion of the International Searching Authority dated May 3, 2012 as received in application No. PCT/CN2011/077718.

   • Publication/Filing Date: May 3, 2012 (Written Opinion date); Application No. PCT/CN2011/077718 was likely filed earlier.
   • Brief Description: This is a procedural document from an international patent application search, indicating prior art found during the examination of the PCT application from which US8891347 likely claims priority. The specific content of the prior art cited within this opinion would need to be reviewed to determine its full relevance.
   • Potential Anticipated Claim(s): Without knowing the specific prior art documents cited within this opinion, it's not possible to definitively state which claims are anticipated. However, generally, such opinions highlight prior art that could anticipate any of the independent claims (1, 8, 15) by demonstrating that the core method or system elements were known or obvious.

2. "3rd Generation Partnership Project; Technical Specification Group. Radio Access Network; Further Advancements for E-UTRA Physical. Layer Aspects (Release 9), 3GPP TR36.814, V0.4.1(Feb. 2009), pp. 1-31."

   • Publication/Filing Date: February 2009.
   • Brief Description: This 3GPP Technical Report discusses "Further Advancements for E-UTRA Physical Layer Aspects," likely covering topics related to LTE-Advanced systems. The patent itself mentions "future generation wireless communications, such as the LTE-Advanced systems" and "coordinated multiple-point (CoMP) transmission techniques" in comparison to its user-focusing technique. This reference likely describes conventional or proposed techniques in LTE-Advanced, particularly CoMP, and aspects of physical layer design that existed before the filing date of US8891347.
   • Potential Anticipated Claim(s): This document could potentially anticipate elements of the independent claims (1, 8, 15) related to general wireless communication systems, transmission of signals, channel estimation, and the use of multiple propagation paths, especially in the context of advanced cellular communication standards. It would serve as prior art for the state of the art in wireless communication technology, particularly regarding CoMP and physical layer aspects, suggesting that some foundational elements of the claimed invention were already known. The patent explicitly distinguishes its "user-focusing" technique from "coherent adding" in CoMP systems, suggesting this reference establishes the known CoMP techniques.

3. Sampath et al., “Pre-Equalization for MIMO Wireless Channels with. Delay Spread', 52nd Vehicular Technology Conference, IEEEVTS. Fall VTC 2000, vol. 3, pp. 1175-1178."

   • Publication/Filing Date: 2000.
   • Brief Description: This paper discusses "Pre-Equalization for MIMO Wireless Channels with Delay Spread." Pre-equalization is a technique where signal distortion is compensated at the transmitter side, similar in concept to the predistortion described in US8891347. The patent states that its "user-focusing" technique has "significant difference from the conventional precoding techniques" and "pre-equalization techniques usually rely on the structure of finite impulse response (FIR) filter, while the user-focusing systems and methods described herein use individual propagation path without requiring a finite impulse response."
   • Potential Anticipated Claim(s): This reference is highly relevant to the "predistorting a second signal at the transmitter" step in claims 1, 8, and 15. It could anticipate the general concept of pre-compensating for channel distortions at the transmitter for MIMO systems. The key to patentability for US8891347 over this prior art would lie in the specific "full-dimensional parametric description of the channel" and pre-distortion across "time, frequency, and spatial domains" that the patent claims as novel, distinguishing it from conventional pre-equalization.

4. Holfeld et al., “Order-Recursive Precoding for Cooperative Multi. Point Transmission'. Proceedings of the International ITG/IEEE. Workshop on Smart Antennas (WSA 2010), 2010, pp.39-45."

   • Publication/Filing Date: 2010.
   • Brief Description: This paper discusses "Order-Recursive Precoding for Cooperative Multi-Point Transmission," another technique related to CoMP systems and precoding. Precoding involves modifying signals at the transmitter to optimize reception, which is a broader category that predistortion falls under. The patent distinguishes its "pre-distortion" from "conventional precoding techniques" by emphasizing the use of "parameters of the propagation channel, e.g. the delay, Doppler frequencies, directions of departure and directions of arrival" rather than simplified channel representations like codebooks.
   • Potential Anticipated Claim(s): Similar to Sampath et al., this reference is highly relevant to the "predistorting a second signal at the transmitter" step in claims 1, 8, and 15. It could anticipate methods of precoding signals in multi-point transmission scenarios. The novelty of US8891347 would hinge on the specific details of obtaining and utilizing a "full-dimensional parametric description" of the channel for predistortion across time, frequency, and spatial domains, which it argues conventional precoding lacks.

5. Saleeb, "Design of a Smart antenna for reducing co-channel interfer ence in cellular mobile communications'. Antennas and Propagation. Society International Symposium, IEEE, 1999, vol. 3, pp. 1620. 1623."

   • Publication/Filing Date: 1999.
   • Brief Description: This paper concerns the "Design of a Smart antenna for reducing co-channel interference in cellular mobile communications." Smart antennas are often associated with techniques like SDMA (spatial division multiplexing access), which the patent also compares its user-focusing technique to. The patent states that "the smart antenna of the SDMA (spatial division multiplexing access) technique can make use of SDMA technique to direct the beam to the certain directions. However, in SDMA, there is no concept of pre-distortion of the signals in time, frequency and space domains, as described above."
   • Potential Anticipated Claim(s): This reference could potentially anticipate aspects of using multiple antennas and directing signals, particularly the "spatial domain" aspect of predistortion in claims 1, 8, and 15. The distinction for US8891347 would be its claim of joint pre-distortion in time, frequency, and space, and the use of full propagation path parameters to create a "focus" on a moving point, which it argues SDMA does not achieve.

6. Fleury et al., “Channel Parameter Estimation in Mobile Radio Envi ronments. Using the SAGE Algorithm”, IEEE Journal on Selected. Areas in Communications, 1999."

   • Publication/Filing Date: 1999.
   • Brief Description: This paper discusses "Channel Parameter Estimation in Mobile Radio Environments. Using the SAGE Algorithm." The SAGE (Space-Alternating Generalized Expectation-maximization) algorithm is explicitly mentioned in US8891347 as one of the channel estimation algorithms that may be used to obtain path parameters.
   • Potential Anticipated Claim(s): This reference directly anticipates the "performing a channel estimation... to obtain path parameter information" step in claims 1, 8, and 15, specifically by disclosing a method (SAGE algorithm) for achieving this. It also potentially anticipates elements of dependent claim 4, which lists the SAGE algorithm as an estimation technique. The novelty of US8891347 would not be the estimation algorithms themselves, but rather their application in the overall user-focusing technique that involves feedback and specific predistortion in three domains.