Abstract: Disclosed are various embodiments for performing retransmission with on-line reconfiguration. A data stream is encoded into first frames according to a framing configuration. A request is obtained for an on-line reconfiguration of the framing configuration from a receiver. The encoding of the data stream into the first frames is suspended in response to the request. One or more first frames are retransmitted to the receiver during a retransmission time period that commences relative to the suspending of the encoding of the data stream into the first frames. The encoding of the data stream into second frames is resumed according to a modified framing configuration consistent with the on-line reconfiguration. The second frames are transmitted to the receiver upon expiration of the retransmission time period.

Abstract: A cognitive radio communication system using a multiple input multiple output (MIMO) communication technology is provided. A cognitive radio base station includes a plurality of antennas, a group setting unit to set at least one sensing terminal group that includes at least one sensing terminal among a plurality of terminals, and a signal generator to generate a transmission signal to transmit the transmission signal using channels formed between the plurality antennas and the plurality of terminals, so that the at least one sensing terminal is accorded a sensing time.

Abstract: Systems and methods for removing a DC offset from an orthogonal frequency division multiplexed (OFDM) signal transmitted over a plurality of subcarrier frequencies. The system includes a receiver. The system further includes a high pass DC component filter configured to reduce a DC component of the orthogonal frequency division multiplexed signal, the high pass DC component filter shaping noise in the orthogonal frequency division multiplexed signal which results in a non-uniform power spectral density of the noise across the plurality of subcarrier frequencies. The system further includes a noise whitener configured to compensate for the noise shaping by the high pass DC component filter by normalizing the non-uniform power spectral density of the noise across the plurality of subcarrier frequencies.

Abstract: A clock extractor extracts clock frequency f2, from a wired data connection feeding the transmitter with data clocked at the clock frequency f2. A clock error estimator estimates clock frequency error between the clock frequency f2 and a clock frequency f1 derived from a local clock of the transmitter. Clock adder adds the clock frequency error to the clock frequency f1, resulting in a synthesized clock frequency f2. A modulator uses the synthesized clock frequency f2, to modulate a data stream into a modulated signal.

Abstract: According to one embodiment, a method of encoding a plurality of orthogonal frequency division multiplexing (OFDM) signals is disclosed. The method includes: modulating the plurality of OFDM signals according to a modulation scheme, wherein the modulated OFDM signals are mapped to a first axis and a second axis perpendicular to the first axis, and correspond to a first constellation having a plurality of points symmetric with respect to the first axis and the second axis; and differentially encoding the plurality of OFDM signals according to a second constellation plurality of points defined by shifting a position of one of the first constellation plurality of points toward an origin located at an intersection of the first axis and the second axis.

Abstract: A demodulation method for a pseudo-heterodyne signal, wherein the pseudo-heterodyne signal has a phase-modulated carrier signal and the pseudo-heterodyne signal is digitally sampled. A demodulation method at least partially avoids the disadvantages known from the prior art is implemented according to the invention in that the digitally sampled pseudo-heterodyne signal is subjected to a discrete Fourier transformation and at least one output Fourier coefficient featuring an amplitude and a phase is determined, an atan2 function (11) is applied on exactly one output Fourier coefficient of the discrete Fourier transformation and the atan2 function (11) provides the phase of the one output Fourier coefficient as a result.

Abstract: An apparatus and a method for estimating a Noise and Interference (NI) power in a communication system are provided. The method includes, calculating average values of impulse responses according to ranging codes, through use of a ranging signal sequence received through a resource allocated to a ranging channel, arranging the average values of the impulse responses according to ranging codes in order of the highest value to the lowest value, and multiplying a ranging code, which corresponds to an impulse response having an (x+1)th peak value among the arranged average values of the impulse responses, by a specific threshold value, and estimating the NI power, wherein “x” represents a number of ranging codes which can be simultaneously received by one ranging channel.

Abstract: In a particular embodiment, a circuit device includes a peak detector to receive a signal and to generate peak output data related to the received signal and an average detector to generate average output data related to the received signal. The circuit device further includes a logic circuit to generate a data output related to the received signal based on the generated peak output data and the generated average output data.

Abstract: A method in a wireless communication system having a forward channel corresponding to transmissions from a first device to a second device, and a reverse channel corresponding to transmissions from the second device to the first device, includes initiating, at the first device, a first update of a steering matrix. The steering matrix is used to beamform transmissions on the forward channel. The method also includes monitoring, at the first device, a plurality of reverse channel estimates corresponding to the reverse channel, determining, at the first device, a metric indicative of a rate of change in the reverse channel based on the plurality of reverse channel estimates, and initiating, at the first device, a second update of the steering matrix based on a comparison between (i) the metric indicative of the rate of change in the reverse channel and (ii) a threshold.

Abstract: Methods and apparatus are provided for adaptively selecting a communications mode in high frequency systems. A first dual-mode device having capabilities of using two or more high frequency communications modes, such as OFDM and SC modulation, may transmit a signal to a second dual-mode device with the same capabilities. The second dual-mode device may compute a channel characteristic associated with a high frequency communications channel and select an optimal high frequency communications mode. The second dual-mode device may transmit information indicative of the channel characteristic or the selected communications mode to the first dual-mode device. The first dual-mode device may select and operate using the optimal high frequency communications mode based on the information received from the second dual-mode device. The first and second dual-mode devices may communicate using the selected high frequency communications mode.

Abstract: In particular embodiments, a broadband receiver of a wireless communications device may poll a broadband communications channel for configuration data. Once the configuration data has been received, the channel may be established, and connection information may be transmitted to a base station. The connection information may be an identifier for a user of a social-networking system. Based on the identifier, the device may be able to establish a narrowband communications channel with the base station. Using the identifier, the base station may be able to begin retrieving social-networking information for the user while establishing a communications channel using the narrowband transceiver. Once the narrowband communications channel has been established, the wireless communications device may be able to receive the social-networking information over that channel and provide social-networking functionality.

Abstract: An improved mobile communications device, of the type having a set of antennas and a narrowband RF transceiver coupled to a first member of the set of antennas, also includes a broadband RF receiver coupled to a second member of the set of antennas; and processing circuitry, coupled to the narrowband RF transceiver and the broadband RF receiver, that uses a received signal from the broadband receiver to determine a communication parameter for the narrowband RF transceiver. Related methods are also provided.

Abstract: Digital logic receives a gapped and jittery clock signal with specified frequency and frequency offset allowed by specification and a reference clock signal with same specified frequency and different frequency offset allowed by specification having low jitter. The digital logic adds and/or removes cycles from the reference clock signal over an extended period of time to produce a produced clock signal with low jitter that has a frequency that approaches the frequency of the gapped and jittery clock signal. The produced clock signal being provided as feedback to the digital frequency comparator and also acts as final dejitter smooth clock output with 50% duty cycle.

Abstract: A method and a circuit are provided for providing phase or frequency synthesis using sigma-delta modulation bit-stream techniques in which data is encoded utilizing sigma-delta modulation and then digital-to-time conversion (DTC) or digital-to-frequency conversion (DFC). In some embodiments this encoded data stream is further subjected to phase or frequency domain filtering, which in some embodiments is carried out by a higher-order phase-locked loop (PLL).

Abstract: A transmission apparatus includes: a multiplier configured to multiply a signal provided on a complex plane by a multiplication coefficient corresponding to a number of transmission sub-carriers; and an inverse fast Fourier transformer configured to perform an inverse fast Fourier transform on the multiplied signal.

Abstract: A linearizer reduces nonlinear intermodulation distortion in radio frequency and microwave systems by first directly generating in-phase and quadrature nonlinear intermodulation products of the system input. Controllable amounts of each phase are then added back into the system such that the vector sum of nonlinear intermodulation products at the output is reduced or eliminated by destructive interference, while the fundamentals are substantially unaffected. The quadrature distorted signals are generated with two lightly-biased and thus overdriven differential pairs having gain-determining degeneration impedances that are in quadrature with each other. The amount of each quadrature phase summed to the output is controlled with electronically tunable four-quadrant variable attenuators. The quadrature phasing enables rapidly convergent tuning to minimize distortion using conventional scalar spectral analysis. The advantages of a linearizer using rectangular vector coordinate system are significant.

Abstract: An orthogonal frequency division multiplexing (OFDM) multiband transmitter (200) adapted to perform multiple-subcarrier-joint-modulation (MSJM) precoding. The transmitter comprises a bit interleaver (220) for independently interleaving bit blocks and grouping bits of each interleaved bit block to bit groups; a symbol mapping unit (230) for mapping each of the bit groups to symbols according to a MSJM scheme; and a symbol interleaver (240) for allocating the symbols to data subcarriers of a plurality of consecutive OFDM symbols.

Abstract: Embodiments of methods and apparatus for fast link recover are disclosed. One method includes sensing a link quality failure of a link between a receiver and a transmitter. If a link quality failure is sensed, then the receiver selects new pre-coder settings for the transmitter. The receiver communicates the new pre-coder settings to the transmitter. The transmitter applies the new pre-coder settings. The receiver computes its equalizer settings based on the new pre-coder settings of the transmitter. One apparatus or transceiver includes a means for determining a link quality failure of a link between the transceiver and a link partner transceiver. The transceiver selects new pre-coder settings for the link partner transceiver if a link quality failure is sensed. Additionally, the transceiver communicates the new pre-coder settings to the link partner transceiver, and computes its equalizer settings based on the new pre-coder settings of the link partner transceiver.

Abstract: A method includes: (a) modulating a set of subcarriers with a set of data to produce a modulated OFDM symbol vector; (b) modulating a FM carrier signal with the set of data to produce a modulated FM symbol; (c) combining the modulated OFDM symbol and the modulated FM symbol to produce a modulated hybrid symbol; (d) limiting the magnitude of the modulated hybrid symbol to produce a first limited modulated hybrid symbol; (e) demodulating the first limited modulated hybrid symbol to recover distorted QPSK constellations; (f) constraining the distorted QPSK constellations to values greater than or equal to a minimum threshold value to produce constrained QPSK constellations; (g) demodulating the modulated hybrid symbol to produce a demodulated hybrid symbol vector; (h) subtracting the demodulated FM symbol vector from the Hybrid symbol vector to produce modified OFDM symbol vector; (i) applying a mask to inactive subcarriers in the plurality of subcarriers of the OFDM symbol vector; (j) modulating an OFDM symbol

Abstract: This disclosure relates to a continuous open loop control to closed loop control transition.