US 9001774

Here is a concise summary of US patent 9001774:

US Patent 9001774: System and method for channel estimation in a delay diversity wireless communication system

• Title: System and method for channel estimation in a delay diversity wireless communication system
• Assignee: Unwired Planet International Ltd (current assignee as of September 8, 2017). The original assignee was [Samsung Electronics Co Ltd](/litigations/by-plaintiff/Samsung%20Electronics%20Co%20Ltd) when the application was filed.
• Inventors: Farooq Khan
• Filing Date: November 12, 2013
• Issue Date: April 7, 2015
• Abstract: The patent describes a method for controlling downlink transmissions to a subscriber station in an Orthogonal Frequency Division Multiplexing (OFDM) network. This method involves the subscriber station receiving first and second pilot signals from a base station's respective antennas, then estimating the channel based on these pilots. The subscriber station determines a set of OFDM symbol processing parameters (relative gains and delays for OFDM symbols transmitted from the antennas) based on this channel estimation and transmits these parameters back to the base station. The base station then uses these parameters to control its downlink transmissions.

Plain-Language Overview of Independent Claims:

• Independent Claim 1 (Base Station Method): This claim describes a method performed by a base station. The base station receives a signal from a subscriber station (an "uplink signal"). Based on this uplink signal, the base station determines a "processing parameter" which can include a time delay, a phase rotation, or a gain. This parameter is used for transmitting data over two antenna ports. The base station then transmits two pilot signals and two data symbols from these two antenna ports. Crucially, at least one of these transmitted data symbols is processed using the previously determined processing parameter.
• Independent Claim 6 (Subscriber Station Method): This claim describes a method performed by a subscriber station (receiver). The subscriber station receives a "processing parameter" (which can be a time delay, phase rotation, or gain) from the base station; this parameter was determined by the base station based on an uplink signal. The subscriber station also receives a first pilot signal, a second pilot signal, a first data symbol, and a second data symbol, all transmitted from two antenna ports. The core of the claim is that the subscriber station then demodulates both received data symbols using the received processing parameter, along with the received first and second pilot signals.

Litigation/Legal Status Note:
The patent US9001774B2 expired on March 27, 2026. The Google Patents record indicates an "Expired - Lifetime" legal status. While the patent itself notes a history of litigation in various courts up to 2022, no specific dockets for US9001774 in the CAFC for 2026 were found during this search.