Abstract: A system to detect a ramp position is disclosed. The system includes a head positioner coupled to an actuator arm to position a head relative to a disk and a controller to: control the head positioner to move the head toward the ramp; determine a plurality of integrator values while moving the head; generate a threshold based on the plurality of integrator values; and determine the ramp position based on a first integrator value exceeding the threshold.

Abstract: The present invention provides a method for channel estimation used in a receiver of a multi-carrier communication system, including: receiving a multi-carrier symbols from a transmitter of the multi-carrier communication system; and obtaining channel information of sub-carriers carrying data of the multi-carrier symbols, using selectively time direction interpolation and frequency direction interpolation for channel information of a plurality of scatter pilots of the multi-carrier symbols.

Abstract: Modem coding and modulation techniques have greatly improved the transmission and reception of signals. A method is described including receiving a signal de-mapping the signal into a first and second substream, decoding the first and second substream using a low density parity check decoding process, and combining the first and second decoded substream into a single data stream. An apparatus is described including a symbol de-mapper that receives a signal de-maps the modulation symbols in the signal into a first and second substream, a first decoder that decodes the first substream using a low density parity check coding process at a first decoding rate, a second decoder that decodes the second substream at a second encoding rate, and a combiner that combines the first substream and the second substream into a single data stream.

Abstract: Modern coding and modulation techniques have greatly improved the transmission of signals. A method is described including receiving a stream of data bits, demultiplexing the stream into a first and second substream, encoding the first and second substream using a low density parity check coding process, and mapping the first substream to a first region of a symbol constellation map and the second substream to a second region. Also, an apparatus is described including a demultiplexer that produces a first and second bitstream, a first encoder that encodes the first substream using a low density parity check coding process at a first encoding rate, a second encoder that encodes the second substream at a second rate, and a symbol mapper that maps bits from the first substream to a first region of a symbol constellation map and maps bits from the second substream to a second region.

Abstract: Methods for congestion control by a AAA server are provided. In an embodiment of the invention a hint indicator is embedded in reply messages from a AAA server. In subsequent messages received by that AAA server, the AAA server determines when the hint indicator is present. Processing decisions for the subsequent message are based on the presence of the hint indicator. In another embodiment, a method for congestion control at the AAA server is provided. At the AAA server a message received from a network access server is stored and timestamped in an ingress message queue. A congestion state for the AAA server is determined based on an ingress queue state and a message age state. The message is processed based on the congestion state. In alternative embodiments, message processing is based on the congestion state, message type and number of round trip messages.

Abstract: A method for protecting signalling information in a frame to be transmitted to a receiver in a communication system, comprising: encoding frame signalling information of the frame to protect the frame signalling information; and encoding Forward Error Correaction FEC block signalling information of FEC blocks in the frame by using Reed-Muller codes to protect the FEC block signaling information.

Abstract: A system and a method for multimedia multicast transmission in a mobile wireless network are proposed, which can be applied in a multiple-antenna system as well as a single antenna system. The basic message and additional message are transmitted at the same time. Receivers with different capability also with different complexities are used to demodulate different message. In order to design low-complexity receiver, the signal can be demodulated noncoherently for multimedia transmission.

Abstract: A Digital Video Broadcasting-Terrestrial/Handheld (DVB-T/H) receiver comprises a controller and a frequency interpolator for use in estimating channel state information (CSI) information of a received signal by frequency interpolation. The controller determines a multi-path delay (Tmax) for the received signal and adjusts the bandwidth of the frequency interpolator as a function of the determined multi-path delay. For example, when the multi-path delay is small, the bandwidth of the frequency interpolator is adjusted to be smaller than the bandwidth of the frequency interpolator when the multi-path delay is large. In addition, the controller may also change the coefficients of the frequency interpolator such that different word lengths are used for the coefficients as a function of the determined multi-path delay.

Abstract: A cable transmitter supports a number of low density parity check (LDPC) coding rates, e.g., 1/4, 1/3, 2/5, 1/2, 3/5, 2/3, 3/4, 4/5, 5/6, 8/9 and 9/10; and supports a number of quadrature amplitude modulation (QAM) schemes, e.g., 4-QAM, 16-QAM, 64-QAM, 256-QAM, 1024-QAM or higher. For a selected modulation scheme, the cable transmitter selects between using a non-uniform symbol constellation or a uniform symbol constellation as a function of a selected coding rate.

Abstract: A concatenated coded modulation communication system and method combines Trellis Coded Modulation with non-Gray code constellation mapping, interleaving, and non-binary Low Density Parity Check coded channel modulation with Gray code constellation mapping to improve error performance.

Abstract: The present invention provides an apparatus and method for concurrently accessing multiple wireless networks, comprising: a host for allocating a plurality of virtual MAC addresses based on the number of the wireless networks to be accessed, and a plurality of virtual MAC devices each having one of the virtual MAC addresses allocated by the host, for accessing the multiple wireless networks concurrently; wherein a physical address of the apparatus is set as a transmitter or receiver address of frames for accessing the multiple wireless networks concurrently.

Abstract: A fast retransmission method by introducing the internal node under better channel condition to join the work of retransmission after the destination node sends out the packet loss indication for unicast services. Extended to serve multicast services, a system comprising a plurality of nodes utilizes the farthest node in each branch from the source to transmit an acknowledge signal when packet loss occurs. The system then enables the closest node to the acknowledging node to retransmit the requested packet, thereby improving the target packet hit rate and data integrity with less retransmission steps.

Abstract: It is provided a method for determining channel quality for a second channel, wherein, the second channel is overlapping with a first channel, the method comprising the steps of sending a request message through the first channel; receiving a response message on the second channel in response to the request message through the first channel; and determining the channel quality of the second channel based on the response message on the second channel. It can be used to determine the channel quality of at least one channel by sending a single message through the first channel.

Abstract: A receiver is a Digital Video Broadcasting-Terrestrial/Handheld (DVB-T/H) receiver. The DVB-T/H receiver comprises a phase error corrector and a channel estimation and equalization element. The phase error corrector rotates a signal in accordance with an estimate of a phase error, e.g., CPE, which is determined as a function of channel state information (CSI) provided by the channel estimation and equalization element.

Abstract: A receiver is a Digital Video Broadcasting-Terrestrial/Handheld (DVB-T/H) receiver. The DVB-T/H receiver comprises a fast fourier transform (FFT) operative on a signal for providing an FFT output signal comprising a number of samples; a spectrum shifter for reordering the samples in the FFT output signal to provide a spectrum shifted signal; and a phase corrector for estimating a phase error from the FFT output signal and for correcting a phase of the spectrum shifted signal in accordance with the estimated phase error.

Abstract: A receiver supports a single carrier (SC) form of modulation and a multi-carrier form of modulation such as orthogonal frequency division multiplexing (OFDM). Upon receiving a signal, the receiver determines a maximum fluctuation range (MFR) as a function of at least a fourth-order cumulant of a received signal; and classifies a modulation type of the received signal as a function of the determined maximum fluctuation range. After determining the modulation type of the received signal, the receiver switches to that modulation mode to recover data from the received signal.

Abstract: A method for automatic gain control used in a receiver of a multi-carrier telecommunication system, the method comprising: receiving an input signal digitalized by an A/D converter; determining distribution of the input signal; and controlling gain of a variable gain amplifier as a function of the determined distribution.

Abstract: A method for symbol synchronization of received digital signal and a digital signal reception apparatus are provided. The method comprises steps of correlating the received digital signal with the received signal delayed by one symbol so as to obtain a first correlation value result as a combined effort of a strongest path and other paths; removing substantially effect of the strongest path from the first correlation result so as to obtain a second correlation result which exhibits contribution of a fastest path; searching a maximum correlation value and its position of the fastest path so as to determine symbol synchronization timing for initiating FFT processing. The digital signal reception apparatus is characterized by a symbol timing detecting unit for determining symbol synchronization timing of the fastest path through substantially removing the effect of a strongest path.

Abstract: The present invention provides a receiver for receiving digital signals including frames with a binary modulated cyclic preamble, comprising: means for correlating at least part of a first cyclic preamble in a first frame and at least part of a second cyclic preamble in a second frame, and for determining a carrier frequency offset based on said correlation.

Abstract: A system and a method are described, whereby a data cache enables the realization of an efficient design of a usage analyzer for monitoring subscriber access to a communications network. By exploiting the speed advantages of cache memory, as well as adopting innovative data loading and retrieval choices, significant performance improvements in the time required to access the necessary data records can be realized.