Invalidity dossier
US 8817904
Method for selecting a precoding matrix in a multiple input multiple output (“MIMO”) system
Current assignee: TIM SpA
Added 9/21/2026, 9:30:40 AM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US8817904B2
Title: Method for selecting a precoding matrix in a multiple input multiple output ("MIMO") system
Patent number / application: US8817904B2; Application US13/520,028; earlier publication US20130003812A1.
Inventors: Ivano Salvatore Collotta, Gian Michele Dell'Aera, Bruno Melis, Fabio Mondin, Paolo Priotti.
Assignee: Original assignee Telecom Italia SpA; current assignee listed as TIM SpA.
Dates: Priority/filing date 2009-12-30; publication 2014-08-26; anticipated expiration 2029-12-30. Legal status listed as Active (an assumption, not a legal conclusion, per the source).
Purpose: The patent concerns MIMO communication systems using precoding. Linear precoding multiplies a layered signal by a "precoding matrix"; the optimum matrix depends on Channel State Information (CSI), typically available at the receiver, so information must be fed back to the transmitter over a rate-limited feedback link. To limit overhead, precoding matrices are chosen from a finite set ("codebook") known to both receiver and transmitter, and the receiver sends the chosen matrix's binary index, the Precoding Matrix Index (PMI). Such codebook-based precoding is used in LTE (3GPP) and WiMAX, for single-layer and spatial-multiplexing (multi-layer) transmission.
Plain-language scope: Disclosed subject matter includes defining a suitable receiver-side selection function for choosing the optimum precoding matrix as a function of current CSI. The selection function depends on receiver type, codebook characteristics, and the metric optimized (e.g., BER, SNR, constellation minimum distance, capacity, practical rank). Selecting the optimum matrix F_m requires computing the SINR of each received layer, which involves inverting a complex n_lay × n_lay matrix, repeated for each matrix in the codebook.
Source: https://patents.google.com/patent/[US8817904](/patent/US8817904)/en
What the excerpt does not establish: It does not provide the full claims or the detailed method steps for reducing matrix-inversion complexity; it does not establish validity, enforceability, current legal status, or ownership beyond the listed assignment data. Classification codes and prior-art keywords are metadata, not findings.
Generated 10/1/2026, 10:02:17 PM
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Assignment history
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Prior art
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