289 results about "Low data rate" patented technology

A dual-band antenna is provided that combines two normally disparate communications modes into a single compact aperture minimizing overall mass and volume, while maintaining high performance efficiency and reciprocity of each individual mode. The antenna is compatible with both optical (near-IR/visible) and RF (microwave/millimeter-wave) transceiver subsystems for high bandwidth communications, applicable primarily to long- to extremely long-range (space-to-ground) link distances. The optical link provides high bandwidth while the RF provides a lower data-rate weather backup, accommodation for traditional navigation techniques, and assistance in cueing the extremely tight optical beam by matching the RF beamwidth to an optical fine-steering mechanism field-of-regard. The configuration is built around a near-diffraction-limited high performance primary mirror shared by both a direct-fed RF antenna design and a Cassegrain optical telescope. Material properties are exploited to combine the optical secondary mirror with the RF feed structure, providing a collimated optical beam interface at the antenna vertex.

Systems and methods for writing a sequence of data to a disk drive using sorted data zones are provided. In one embodiment, a multi-head disk drive comprises a plurality of disk surfaces, wherein each disk surface comprises a plurality of data zones, each data zone having a data transfer rate different from the other zones of the respective disk surface. The multi-head disk drive also comprises a head assembly comprising a plurality of heads, wherein each head is configured to write data to a respective one of the disk surfaces, and a controller configured to operate the plurality of heads to sequentially write a sequence of data blocks to the plurality of disk surfaces in accordance with a list of head-zone combinations ordered from highest data rate to lowest data rate, each head-zone combination corresponding to one of the heads and a data zone of the respective disk surface.

Embodiments provide an “always-on,” accurate, low power, and low cost solution for indoor positioning. The indoor positioning solution is enabled by one or more low power, low cost location beacons, which can be easily configured and installed in any indoor environment to support position determination. In an embodiment, the location beacons use a low power, low data rate wireless radio technology (e.g., Bluetooth Low Energy (BLE)), well suited for typical indoor ranges and data rates needed to support positioning. The location beacons may be rechargeable via ambient light and require no external power source. In addition, the location beacons benefit from a very cost efficient design, which allows for ubiquitous utilization of the enabled indoor positioning solution in a variety of indoor locations, public or private, small or large.

A wireless communications basestation that utilizes a light weight high directivity electronically-steerable antenna mounted on a lighter-than-air vehicle to providing relay broadband communication service among mobile units in a geographic area is provided. The lighter-than-air vehicle carries aloft the antenna; a radio and a switching device for routing. A gateway may also be provided to enable communications with a wide area network. A communication system for a geographic area utilizing the airborne wireless communications basestation is also presented. The system includes a number of user equipment units located in the geographic area in communication with the airborne wireless communications basestation. The user equipment units may utilize omni-directional antennas for low data rate communications, and/or a high directivity antenna.

A system, method and apparatus for managing uplink radio resources. The RRAM employs selective rate reduction to ensure resources for subscriber stations depending on individual QoS requirements. In response to a request for a new DDCH, the RRAM can drop a subscriber station at a low data rate and no media reservations. In response to traffic measurement reports from the subscriber stations, the RRAM attempts to increase or decrease the data rate of a subscriber station. When there are insufficient uplink resources, RRAM tries to lower the rate of a higher rate subscriber station. Searching for subscriber stations to lower, RRAM starts at the highest rate and continues to search lower data rates until a suitable candidate is found. RRAM also reserves resources for subscriber stations that will not be reallocated to other subscriber stations.

A system and method for using computer image processing for selectable task-based digital video compression is described. The system is intended to reduce travel of experts and let these experts direct field agents in performing tasks remotely. The tasks to be performed in the remote field can be monitoring, manipulating, and navigating. A field agent performs the manipulation and navigation operations, this agent can be a human being or a robot. The task-based compression algorithms use computer vision techniques to extract the bare minimum amount of information from the remote field scenery to allow the task to be performed. High frame rate photo-realistic reconstruction of the remote scene is not generally necessary.

A communication system such as an OFDM or DMT system has nodes which are allowed to transmit continuously on one or just a few of the system's frequency sub-channels, while the other nodes avoid putting any signal into those sub-channels. Simple low data rate nodes are allowed to use a small number of sub-channels while more complicated nodes use the remainder. A control protocol allows the sharing in time of communications using overlaid and non-overlaid multi-carrier communication techniques. The sharing in time can be done using TDMA, CSMA or polling techniques. In each case, mechanisms are provided for bringing new nodes into the network and for insuring the time alignment of overlaid transmissions. Reliable transmissions are insured through acknowledgement and retransmission facilities.

A communication system such as an OFDM or DMT system has nodes which are allowed to transmit continuously on one or just a few of the sysiem's frequency sub-channels, while the other nodes avoid putting any signal into those sub-channels. Simple low data rate nodes are allowed to use a small number of sub-channels while more complicated nodes use the remainder, and preferably functionality is provided to ensure that adjacent sub-channels are reliably spaced apart in frequency so that they do not bleed over into one another; to ensure that signals from all nodes arrive at the base station with well-aligned symbol transitions; and to ensure that signals from the various nodes arrive at the base station with similar power levels.

A burst-mode differential phase shift keying (DPSK) communications system according to an embodiment of the present invention enables practical, power-efficient, multi-rate communications between an optical transmitter and receiver. An embodiment of the system utilizes a single interferometer in the receiver with a relative path delay that is matched to the DPSK symbol rate of the link. DPSK symbols are transmitted in bursts, and the data rate may be varied by changing the ratio of the burst-on time to the burst-off time. This approach offers a number of advantages over conventional DPSK implementations, including near-optimum photon efficiency over a wide range of data rates, simplified multi-rate transceiver implementation, and relaxed transmit laser line-width requirements at low data rates.

The invention relates to a cascaded scheme in which an RRC filter, a modified RRC filter or other digital filter is implemented at a relatively low data rate, such as twice the symbol or chip rate, or 2×. Interpolation filters are used to increase the data rate to a higher data rate, such as 8×. Decimation filters are used to reduce the data rate from a higher rate, such as 8×, to a lower rate, such as 2×. The coefficients of the digital filter may be adjusted to compensate for characteristics of other components across the entire filter chain. Most of the implementation complexity of the filter chain is consolidated into the relatively low rate (such as 2×) digital filter while interpolation or decimation filters can be implemented at very low cost. The compensation capability provided by the digital filter makes design of simple decimation or interpolation filters much easier. The compensation capability provided by the digital filter, along with the relatively high over-sampling rate for the output of the interpolation filter (or the input of the decimation filter), also makes the design of the preceding (or following) analog filters much easier.

A method and apparatus are provided for automatic data rate control in wireless communication systems, such as wireless LANs. A data rate controller adapts a transmission rate of said data based on a signal quality and a transmit power level. The data rate controller can also adapt the transmission rate based on one or more of amplifier non-linearities, anticipated signal quality for a next frame transmission, regulatory emission limits and data rate advice. The data rate advice will decrease a data rate if a current signal quality is below a minimum required signal quality for a given data rate and increase a data rate if a current signal quality is above a minimum required signal quality for a given data rate. A probation mechanism allows a higher rate to be evaluated before switching to the higher rate permanently. A retry balance mechanism forces a rate fallback when a number of failed transmission exceeds a predefined threshold. A rate fallback feature reduces the transmission rate when a number of failed transmission exceeds a predefined threshold.

In a communication network (20), a video encoder/decoder system (114) and an encoding method (150) facilitate transmission of video frames (116) over multiple low-data-rate channels (46). Frame data (204) is generated for each video frame (116). The frame data (204) is transformed (172) to obtain transform coefficients (212), which are assembled (174) into quadtrees (216) and separately coded (178). In addition, motion vectors (166) are split into coding blocks (188) and separately coded (190). The quadtrees (126) and the motion vectors (166) are independently distributed among the multiple channels (46) for transmission. A decoding method (360) facilitates error resilient reception of transform coefficient packets (222) and motion vector packets (244) so that lost transform coefficients (374) and/or lost motion vectors (384) can be estimated at a receiving video encoder/decoder system (114) to reconstruct a received video frames 144.

The present invention provides methods, apparatus and systems for delivery of digital data to stationary receivers over a terrestrial wireless link at a low data rate using a new coded orthogonal frequency division multiplexing (COFDM) scheme. Digital data is encoded and modulated using coded orthogonal frequency division multiplexing (COFDM) to produce a data stream. The data stream is communicated to a stationary receiver via a terrestrial wireless link having a ratio of (i) 50% coherence bandwidth to (ii) allocated channel bandwidth of not greater than 50%. The COFDM scheme employed by the present invention overcomes the degradation of multipath fading induced by terrestrial channels, such as the Ultra High Frequency (UHF) broadcast channel.

A wireless communication module to provide security at a baseband layer is disclosed. A payload of plaintext may be divided into partitions. The module may use a block cipher such as the Advanced Encryption Standard (AES) algorithm to process a unique initiation vector (IV) for each partition so that each partition may be XORed with a key stream based on a respective IV, the result providing ciphertext. The IV may include a nonce, an upper level packet counter, a packet counter and a block counter. The state of the counters may be incremented in a predetermined pattern so as to provide a unique IV for use with each partition. The ciphertext may be transmitted in a packet with a security bit indicating that the payload is encrypted but omitting the nonce. Encrypted packets may include an integrity check value (ICV) to provide for integrity of the encrypted message.

A communication system (100) is provided that comprises a Radio Access Network (110) having a Radio Network Controller (RNC) (114) coupled to each of a cellular Node B (112) and a Digital Broadcasting Video-Handhelds (DVB-H) Node B (120). When the communication system delivers low rate Multimedia Broadcast/Multicast Service (MBMS) user information, the user information is conveyed via the cellular Node B and a low data rate channel. When the communication system delivers high rate MBMS user information, the user information is conveyed via the DVB-H Node B and a high data rate channel. Thus the communication system provides high rate MBMS data services without imposing the system capacity constraints resulting from the employment of HSDPA by a cellular Node B.

A serial interface for a programmable logic device supports a higher physical medium attachment (“PMA”) data rate than the available physical coding sublayer (“PCS”) data rate by using multiple PCS modules, operating in parallel, to support one PMA module. In a channel-based structure, the PMA module is supported by a PCS module in its own channel and at least one PCS module from a second channel. The second channel may include its own PMA module which, if provided, may operate at a lower rate, supportable by the PCS module in that channel. Optionally, two modes are provided. In one mode, two PCS modules in two channels support one higher-speed PMA module in one of the channels. In a second mode, each PCS module supports a PMA module in its own channel, with the higher-speed PMA module constrained to operate at the lower data rate of the PCS module.

In one illustrative example, a wireless network device of a low data rate wireless personal area network (WPAN) or the like includes a controller, memory for storing one or more application programs, and a wireless transceiver coupled to the controller and operative for communications in the wireless network. The controller is adapted to receive, through the wireless transceiver, an instruction which causes the wireless device to operate as a client in performing an OAD procedure for receiving the program from another wireless device which is operated as a server in the wireless network, and to operate the wireless device as the client in performing the OAD procedure in response to such instruction. The controller is further adapted to receive, through the wireless transceiver, one or more instructions for the wireless device to operate as a server in performing the OAD procedure for sending the program to one or more other wireless devices which are operated as clients in the wireless network, and to operate the wireless device as the server in performing the OAD procedure in response to such instructions. A, commissioner device of the wireless network may coordinate the assignment of client and server roles of the wireless devices for OAD procedures based on a variety of different heuristic or algorithmic techniques for optimal results.

A method of communication between computing entities in a local area network operating an CSMA protocol in an environment where reflections of omni-directional transmissions from a plurality of objects cause multi-path fading includes data packets being transmitted having a header at a first, lower data rate, followed by transmission of payload data at a second, higher data rate. Where the packets are not confirmed to be received, the packet is retransmitted a predetermined number of times before the transmitting entity reduces the payload data rate of the packet and retransmits the packet. If the retransmitted lower payload data rate packet is not confirmed to be received within the predetermined number of transmissions at the lower rate, the packet is dropped.

A method and apparatus for resource allocation in a multi-carrier wireless communication system enables transmission using smaller resource units and achieves efficient transmission of data channels with very low data rates, scheduling a greater number of user equipments without additional control channel overhead while maintaining compatibility with the resource allocation scheme of legacy user equipments. Thus, one cell controls a larger number of user equipments. In addition, as multiple user equipments are scheduled using a single control channel, resource efficiency is increased.

A method is provided for providing communication and surveillance services to a mobile platform. The method includes substantially simultaneously communicating between a plurality ground based antennas and a plurality of satellites. Particularly, each ground based antenna communicates with a related one of the satellites. The method additionally includes substantially simultaneously communicating between each of the satellites and at least one multi-faceted electronically scanned antenna included in a mobile platform communication system onboard a mobile platform.