Abstract: A multi-user MIMO downlink beamforming system with limited feedback (200) is provided to enable precoding for multi-stream transmission, where a channel codeword (ui) and one or more channel quality indicator values (CQIA, CQIB) are computed at the user equipment (201.i) on the basis of maximizing a predetermined SINR performance metric (?i) which estimates the receive signal-to-noise-ratio (SINR) at the user equipment (201.i). The computed codeword (ui) and CQI values (or differential values related thereto) are quantized and fed back to help the base station (210) which applies a correction to the appropriate CQI value in the course of designing the transmit beamforming vectors w and determining the appropriate modulation and coding level to be used for downlink data transmission.

Abstract: A facility is described for providing conference roll calls that identify participants in electronically facilitated conferences. In various embodiments, the facility receives identifiers of participants in an electronically facilitated conference and displays a list of the participants in a roll call. The list can include indications of which participant is speaking, whether participants are authenticated, and other information associated with the participant, such as the participant's name.

Abstract: The invention provides a system and a method for securely providing a secret data from a sender to one or more receivers. The receiver uses a sequence of functions originating from a hierarchy of functions to migrate the secret data from an input transform space to an output transform space using a mathematical transformation under control of one or more seeds. The seeds are provided to the receiver by the sender. The sender conditionally allows the receiver to obtain the secret data by controlling the seeds.

Abstract: A system to interface analog-to-digital converters to inputs with arbitrary common-modes includes a common-mode voltage amplifier circuit and a PGA circuit connected to the common-mode voltage amplifier circuit. The common-mode voltage amplifier and PGA circuits receive first and second analog input signals. The PGA circuit eliminates the arbitrary common-modes from the first and second analog input signals based on an output of the common-mode voltage amplifier circuit.

Abstract: Information indicative of the placement of spindle motor components may be obtained and used to provide a correction to one or more BEMF-derived attributes used to control the spindle speed. In some implementations, first and second signals indicative of BEMF of different stator windings may be used to determine a speed-related characteristic. The speed related characteristic may be used to determine an error amount, which may be used to determine a correction factor to control the speed of the spindle motor.

Abstract: Trellis-based methods for reducing feedback while maintaining performance in a Multiple Input, Multiple Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) system. The methods involve: receiving a plurality of symbols from a plurality of sub-carriers at a receiver; selecting a plurality of indices of codewords corresponding to a codebook of pre-coding weighting matrices for the sub-carriers based on vector quantization compression of the codewords, including selecting a plurality of indices based on trellis-based feedback encoding; and transmitting the selected indices over a wireless channel to a transmitter. Optimal precoding matrices are selected at the same time for all subcarriers by searching for the optimum choice of matrices along a trellis. Selecting a plurality of indices based on trellis-based feedback encoding includes constructing a trellis by specifying a state transition table.

Abstract: Methods and systems are shown that specify using group counters and track counters to reduce the need for adjacent-track-erasure (ATE) refresh. A group threshold may be used to monitor the number of write operations to a group. The group threshold may be used to determine when it is necessary to monitor the write operations to the tracks in a group on an individual basis.

Abstract: An apparatus includes a storage medium, an arm for positioning a recording head adjacent to the storage medium, and a controller for receiving objects and for selecting blocks on the storage medium to be written by the recording head based on information in the objects. A method for storing objects is also provided. In another aspect, the invention provides a method for writing data in data storage devices. The method includes: receiving access commands for objects, selecting blocks on a storage medium to be written by a recording head based on information in the objects, and writing data from the objects to the selected blocks.

Abstract: A system includes a control module and an estimating module. The control module controls a speed of an actuator arm when the actuator arm moves from a parked position to an edge of a rotating storage medium and generates an arm control signal. The estimating module estimates a force to move the actuator arm based on the arm control signal and the speed, and generates an estimated force signal that adjusts the arm control signal.

Abstract: A disc drive head actuator includes a suspension structure and a slider integrated with the suspension structure. The actuator is one of at least two actuator assemblies batch-fabricated on a common substrate. The head actuator may be fabricated using mircofabrication techniques. The head actuator may have a reduced size, including package height relative to conventionally manufactured disc drives. Using mircofabrication and/or batch fabrication techniques provides reduced tolerances, which allows for increased actuation forces and/or reduced power consumption. Some embodiments include four-bar linkage actuators, which increase lateral stiffness of the actuator, allowing for a precise motion of the head relative to a media surface.

Abstract: A head lift body (42) with a head assembly (30) mounted thereon has a nut (45) engaged with a lead screw (41). The head lift body has an integral structure formed by resin molding with a through hole, a hollow opening, and a guide portion (47). The through hole receives the lead screw inserted therethrough. The hollow opening is formed at the center of the head lift body to accommodate a backlash preventing mechanism (43). The guide portion inhibits the rotation of the head lift body and guides the head lift body moving up and down along a rotation center axis of the lead screw. The backlash preventing mechanism comprises a preload bushing (431) and a preload spring (432). The preload bushing has an internal thread to be engaged with the external thread of the lead screw. The preload spring presses the head lift body against the preload bushing along the rotation center axis of the lead screw.

Abstract: A magnetoresistive element, comprising a crystal structure with a grain boundary formed at a misorientation angle, and a method of producing a crystal structure having colossal magnetoresistance, wherein a grain boundary is formed at a misorientation angle. The crystal structure comprises a substrate layer and a CMR film layer epitaxially grown thereon, the CMR film layer having a plurality of first sections and a plurality of second sections with intermediate grain boundaries, the crystallographic axis of the first sections being different from the crystallographic axis of the second sections.

Abstract: An improved bearing cartridge to rotationally couple an actuator block supporting a plurality of heads to a chassis of a disc drive. The improved bearing cartridge having increased radial stiffness and including first and second concentrically aligned elongated sleeves. The first sleeve is coupled to the chassis and the second sleeve is coupled to the actuator block. The first and second sleeves are spaced to define a rotation gap therebetween. The bearing cartridge includes first and second spaced bearings positioned proximate to opposed ends of one of said first or second sleeves and at least one intermediate bearing spaced from the first and second bearings and positioned between the first and second bearings to rotationally connect the first and second sleeves.

Abstract: The two-stage actuator comprises a fine actuator 2 with an HGA 1, and a coarse actuator 10, which supports the fine actuator 2 secured to it and is rotatably supported. The fine actuator 2 includes an I shape spring 3, a small coil 4 and a yoke 5. The coarse actuator 10 includes a yoke base 8 with permanent magnets 9, facing the small coil 4. The I shape spring 3 has a longitudinally intermediate portion secured to a set set pin member 7 of the coarse actuator 10. A drive force generated in the fine actuator 2 as a result of energizing the small coil 4 with current application thereto, causes flexing of a leaf spring part of the I shape spring 3, thus fine driving the HGA 12 disposed in the fine actuator 2.

Abstract: A stiffener attached to the magnetic head or heads in a tape drive to support the flexible circuit and provide a flat surface against which the flexible circuit rolls when the head moves up and down. The stiffener is, preferably, fastened to a head carrier that is attached directly to the magnetic head. This head sub-assembly is mounted to the movable carriage that carries the head up and down at the urging of the head positioning actuator.

Abstract: A disc drive microactuation system finely positions a transducing head carried by a slider adjacent a selected radial track of a rotatable disc. An electromagnetic microactuator having a stator and a rotor operatively connected to the slider is provided on a substrate. The rotor is movable with respect to the stator to effect fine movement of the slider. A magnetic shield layer is provided on the substrate for shielding the electromagnetic microactuator.