Abstract: Multiple-In Multiple-Out (MIMO) techniques are used to increase spectral efficiency of a cellular single frequency network. In some embodiments with single transmit antenna per cell, multiple data streams are transmitted from multiple cells, one data stream per set of transmit antennae. The mapping of streams to antenna sets is permuted in time. In this way, user equipment devices (UEs) at cell edges benefit from MIMO, and UEs near cell centers benefit from high carrier-to-interference (C/I) ratio of the signal. In some embodiments, each stream is concurrently transmitted on base layer of a hierarchically modulated signal from one set, and on enhancement layer of a hierarchically modulated signal from another set. The mapping of sets to streams is permuted in time. The UEs at cell edges benefit from MIMO, and the UEs near cell centers benefit from the high C/I to decode both streams from the base and enhancement layers.

Abstract: A mobile station for wireless communication includes a control processor configured to generate a message for transmission on a reverse signaling channel, the message including a Station Class Mark field having a plurality of bits, a portion of the Station Class Mark field indicating that the mobile station is uniquely identified by a Mobile Station Equipment Identifier.

Abstract: In a wireless network (100) with HSDPA-enabled user equipment devices (130), the base transceiver station (120) transmits to each HSDPA-enabled UE information regarding allocation of HSDPA codes and associated modulation techniques for other HSDPA-enabled UEs. Using this additional control information, each UE configures decision feedback filter of its equalizer to reduce inter-user interference. The additional control information may be transmitted in a packet (300) that includes a CRC portion (310) with the packet's CRC masked by a common ID, which is known to the HSDPA-enabled UEs. To reduce the number of bits needed to transmit the additional control information, the HSDPA codes used with a particular modulation technique are allocated consecutively. For each modulation technique, only the beginning code and the total number of codes need be known to the UEs. The number of codes used with each modulation technique may be allowed to change once in several TTIs.

Abstract: A method and apparatus for resolving ambiguity in reception of multiple retransmitted frames includes ascertaining for each data frame received from a transmitter whether the frame is a retransmitted frame. If the frame is a retransmitted frame, the frame may be stored in a resequencing buffer. If an abort timer associated with the second round of retransmission has been set for the retransmitted frame, an associated negative-acknowledgment-list (NAK-list) entry is not removed from a NAK list until the abort timer has expired. If the abort timer has not been set for the retransmitted frame, the associated NAK-list entry is removed from the NAK list. The method and apparatus may reside in a transport function in which a transmitter sends data frames to a receiver in accordance with the Radio Link Protocol interface. The transport function may reside in, e.g., a data-capable cellular or satellite-based base station and subscriber unit.

Abstract: A base station in a wireless communications network counts mobile stations receiving broadcast content via multi-user channel. The base station broadcasts a repeating message identifying at least one broadcast content stream and, for each stream, a REGISTER (R) or DO NOT REGISTER (DNR) indicator. Mobile stations periodically re-examine contents of this message. When the indicator is R for a broadcast content stream, mobile stations whose users have elected to receive it send the base station a registration message for that stream. When the number of registered mobile stations reaches a prescribed number, the base station changes the indicator to DNR. When the indicator is DNR for a broadcast content stream, mobile stations refrain from sending any registration message for that broadcast content stream. The base station may institute a recount by resetting the indicator to R.

Abstract: A disk drive includes a disk drive base. The disk drive further includes at least one rotatable disk including a disk surface extending to an outer disk edge. The disk drive further includes a head stack assembly rotatably attached to the disk drive base in operable communication with the disk. The disk drive further includes an airflow suppressor comb coupled to the disk drive base and stationary relative to the disk drive base during operation of the disk drive. The comb includes a comb body disposed adjacent to the outer disk edge, and at least one tine extending from the comb body along the disk surface for mitigating disk rotation induced airflow upon the head stack assembly adjacent to the disk surface. The comb further includes a curved extension extending along the outer disk edge for mitigating turbulent airflow adjacent the outer disk edge.

Abstract: A disk drive includes a disk having a recording surface and a head stack assembly that includes an actuator body; an actuator arm cantilevered from the actuator body and including a head for reading and writing on the recording surface; a coil cantilevered from the actuator body in an opposite direction from the actuator arm, the coil defining a first leg and a second leg and a damping magnet disposed between the first and second legs. The damping magnet is configured to exert a damping force on the head stack assembly that is greater when the head is at a predetermined non-operational position than when the head is over the recording surface.

Abstract: An aspect of the invention can be regarded as a spindle motor. The spindle motor includes a rotor and a stator. The rotor includes a first plate defining a circular first plate periphery disposed about a central axis, a second plate defining a circular second plate periphery disposed about the central axis, and a magnet defining a circular periphery disposed about the central axis between and parallel to the first and second plates. The stator includes a plurality of magnetic flux guides distributed radially about the rotor.

Abstract: A disk drive is connectable to a power supply voltage and includes a spindle motor, a spindle motor driver, a spindle motor controller, and a detector. The spindle motor has windings and a rotatable rotor. The spindle motor driver is connected to the windings and connectable to the voltage. The spindle motor controller commands the spindle motor driver to apply the voltage across at least one of the windings to cause the rotor to rotate, which induces a BEMF having a polarity across each of the windings.

Abstract: A disk drive is disclosed comprising a base, a disk, an actuator arm comprising a tang attached to a base end of the actuator arm, a head attached to a distal end of the actuator arm, a voice coil motor for rotating the actuator arm about a pivot to position the head radially over the disk, and a crash stop comprising injection molded plastic formed into a body piece having a protruding first arm and a protruding second arm. The body piece of the crash stop is attached to the base of the disk drive. The first protruding arm comprises a magnet at least partially embedded into the plastic for latching the tang of the actuator arm to the first protruding arm. The plastic is formed around the magnet such that at least part of the plastic is between the magnet and the tang. The second protruding arm presents a physical barrier to the tang to limit the stroke of the actuator arm.

Abstract: A disk drive is disclosed comprising an actuator arm, a head coupled to the actuator arm, and a voice coil motor for actuating the actuator arm to move the head. The voice coil motor comprises a first magnet for generating a first magnetic flux, and a yoke comprising a magnetic flux conductor for guiding the first magnetic flux. The magnetic flux conductor comprises a body and a top and bottom protruding plate portions, wherein the body and the plate portions are integrally formed. The body defines, in vertical cross section, a primary bend having a primary bend radius and at least one secondary bend having a secondary bend radius.

Abstract: A disk drive includes a head gimbal assembly and a disk that includes a recording surface. The head gimbal assembly comprises a load beam, the load beam including a first load beam surface facing toward the recording surface and a second load beam surface facing away from the recording surface, a plurality of conductors at least partially supported by the first load beam surface, each conductor including a proximal conductive pad, a distal conductive pad and a conductive path between the proximal and distal conductive pads, the proximal conductive pad being closer to a pivot axis than the distal conductive pad, a gimbal coupled to the load beam, the gimbal including a gimbal proximal end that supports the respective distal conductive pads and a gimbal distal end, and a head for flying above the recording surface of the disk while reading magnetic data recorded on the recording surface of the disk as the disk spins in a rotational direction.

Abstract: An aspect of the invention can be regarded as an actuator arm assembly which includes an actuator arm having an actuator bore. The actuator arm is configured to pivot about an axis of rotation. The actuator bore has pivot sleeve contact areas. The actuator arm assembly includes a pivot cartridge which includes a pivot sleeve which is formed to exert compressive force radially from the axis of rotation. The pivot sleeve is formed to locally deform radially relative to the axis of rotation adjacent the pivot sleeve contact areas. The pivot cartridge includes a bearing outer race. The pivot cartridge includes a bearing gap formed between the bearing outer race and the pivot sleeve for inhibiting transfer of force between the pivot sleeve and the bearing outer race.

Abstract: An aspect of the invention can be regarded as a method of balancing a rotary actuator for use in a rotatable head stack assembly (HSA) portion in a disk drive. The rotary actuator has a pivot axis, and the rotatable HSA portion has an installed HSA portion center-of-gravity. The method provides for deetermining a desired rotary actuator center-of-gravity location for locating the installed HSA portion center-of-gravity along the pivot axis for mitigating acceleration of the rotary actuator about the pivot axis due to external linear acceleration experienced by the disk drive during a track-follow operation. The method further provides for measuring weight distribution characteristics of the rotary actuator to determine an actual rotary actuator center-of-gravity. The method further provides for selectively modifying weight distribution characteristics of the rotary actuator to locate the actual rotary actuator center-of-gravity at the desired rotary actuator center-of-gravity location.

Abstract: A disk drive is disclosed comprising a bistable latch for latching an actuator arm in a latched position. The bistable latch comprises a latch base comprising a first groove and a second groove, wherein a depth of at least part of the first groove is different than a depth of at least part of the second groove. The bistable latch further comprises a latch arm movable with respect to the latch base, the latch arm comprising a guide member interacting with the first and second grooves for guiding the latch arm through a predetermined trajectory. The bistable latch further comprises a spring having a first end connected to the latch base and a second end connected to the latch arm.

Abstract: A disk drive is disclosed with reduced resonance. The disk drive comprises a disk, a fixed spindle shaft disposed axially through the disk, a spindle motor for rotating the disk about the fixed spindle shaft, wherein a resonance is associated with the spindle motor rotating the disk. The disk drive further comprises a head, an actuator arm for actuating the head radially over the disk, a base, and a cover attached to the base to form a head disk assembly chamber. The cover comprises a shaft aperture positioned over the fixed spindle shaft, the shaft aperture for receiving a fastener for attaching the cover to the fixed spindle shaft. The cover further comprises a plurality of slots proximate the shaft aperture, wherein the shaft aperture and slots provide a flexible support for the fixed spindle shaft which reduces the resonance associated with the spindle motor.

Abstract: A head disk assembly includes a disk, a head stack assembly and a ramp-defining structure. The disk has a recording surface surrounded by an outer circumference and the head stack assembly has an actuator pivot axis and a head gimbal assembly. The head gimbal assembly includes a gimbal defining a gimbal axis parallel to and spaced a first distance from the actuator pivot axis, and a lift tab having a lift-surface portion spaced a second, larger distance from the actuator pivot axis. The ramp-defining structure includes a wall extending parallel to the actuator pivot axis, an axis-defining portion defining a retraction pivot axis and a shelf projecting from the wall to define a bearing surface against which the lift-surface portion slides during unloading and loading operations.

Abstract: A disk drive including a head disk assembly, a planar printed circuit board and a vibration damping system. The vibration damping system is fixed adjacent the outer surface of the printed circuit board and includes an external planar member of compressible foam composition and a substantially-planar rigid mass damper of like shape and extent and arranged so that the external planar member contacts both the outer surface of the printed circuit board and the upper major surface of the mass damper. The major surfaces of the mass damper include upwardly-convex bosses for receiving fastening screws to maintain a predetermined separation distance between the printed circuit board and the mass damper that is somewhat less than the unconstrained thickness of the external planar member of compressible foam composition.

Abstract: A spindle motor for a disk drive includes a shaft, an upper bearing, a lower bearing, a stator, a hub and wire guide body. The upper bearing surrounds the shaft. The lower bearing surrounds the shaft, is spaced-apart from the upper bearing, and includes an inner race. The stator surrounds the shaft between the upper bearing and the lower bearing, and includes a stator wire extending from a stator core. The hub is concentrically positioned about the stator. The wire guide body is secured between the shaft and the lower bearing, and includes a generally cylindrically shaped surface and a channel. The channel is sized to receive the stator wire and is formed adjacent to the cylindrically shaped surface such that the channel opens into at least one of the shaft and the inner race.

Abstract: A disk drive includes a disk drive base, a spindle motor, a first disk and a disk clamp. The rotary hub of the spindle motor includes a generally cylindrically-shaped hub wall and a hub flange including an inner annular surface adjacent to the hub wall, an outer annular surface and a flange land portion integrally formed with the hub flange. The land portion is positioned between the annular surfaces and defines a disk contact surface projecting above the annular surfaces, the disk contact surface being substantially centered on the hub flange. The first disk is supported by the disk contact surface to form a clearance between the annular surfaces and the first disk. A second disk may be coupled to the spindle motor and an annular disk spacer may be positioned between the disks. The annular disk spacer includes a first spacer surface facing the first disk and a second spacer surface facing the second disk.