924 results about "Phase-shift keying" patented technology

A WCDMA system includes a Base Station (BS) or forward transmitter and a pilot channel that transmits control signals between a Mobile Station (MS) and BS to reconfigure their transmitter/receiver according to the prediction of the channel power and channel power probability density function separated into three distinct equal probable regions. Data signals are encoded using a one-half Viterbi encoder and interleaved. The interleaved data bits are modulated using Quadrature Phase Shift Keying (QPSK) modulation. The QPSK data is multiplexed with the pilot channel and spread by an appropriate code in an OFDM transmitter modified by a long code. Output of the transmitter may be provided to two diverse antennas for reliable communications to the receiver. Data may be received at two diverse antennas. The outputs are provided to match filters coupled to a coherent rake receiver and a channel prediction system. The future attenuation of the channel coefficients and power are determined by the prediction system for several milliseconds. The power levels of each finger in the Rake receiver can be predicted and the strongest ones used in determining the optimum transmitter power or rate control for operating the system transmitters and receivers based on computing a long range power prediction of each finger of a rake receiver.

A method is provided for an equalization strategy for compensating channel distortions in a dual-polarization optical transport system wherein the received signal includes a complex signal of a first transmitted polarization component and a complex signal of a second transmitted polarization component. In a first step, a blind self-recovery mode used a blind adaptation algorithm in calculating and modifying multiple complex equalizer transfer function coefficients to enable recovery of only the complex signal of the first transmitted polarization component. By recovering only a single polarization component in the first step the degenerate case of recovering only a single transmitted signal at both polarization component outputs of an equalizer is prevented. In a second step, equalization is performed in a training mode for calculating and modifying the multiple complex equalizer transfer function coefficients to enable recovery of the complex signals of the first and second transmitted polarization components. In a third step, equalization is performed in a data directed mode for continuing to calculate and modify the multiple complex equalizer transfer function coefficients to ensure continued recovery of the complex signals of the first and second transmitted polarization components. The method is suited for a digital signal processing implementation in a coherent receiver when a modulation scheme used on a transmitted signal is quadriphase-shift keying (QPSK). In other embodiments, the method can be used with modulation schemes such as binary PSK, M-ary PSK where M>4, or Quadrature Amplitude Modulation (QAM).

A method and apparatus for transmitting uplink acknowledge information (ACK) in a communication system using an orthogonal frequency division multiple access (OFDMA) scheme. The method includes receiving a data bit for the uplink ACK; outputting codewords corresponding to the data bit; performing quadrature phase shift keying (QPSK) modulation on symbols for ACK vector indexes corresponding to the codewords for the received data bit; performing inverse fast Fourier transform (IFFT) on a transmission signal having subcarrier clusters to which the modulated transmission symbols are allocated; and transmitting the IFFT-processed transmission signal.

A PHY entity for a UWB system utilizes the unlicensed 3.1-10.6 GHZ UWB band, as regulated in the United States by the Code of Federal Regulation, Title 47, Section 15. The UWB system provides a wireless pico area network (PAN) with data payload communication capabilities of 55, 80, 110, 160, 200, 320 and 480 Mb/s. The UWB system employs orthogonal frequency division multiplexing (OFDM) and uses a total of 122 sub-carriers that are modulated using quadrature phase shift keying (QPSK). Forward error correction coding (convolutional coding) is used with a coding rate of 11/32, 1/2, 5/8 and 3/4.

The invention relates generally to the field of wireless communications and more particularly to a method of and device for detecting the presence of a received data packet in a digital receiver. The present invention proposes a simplified method of correlation by removing dependency on the amplitude fluctuations while at the same time maintaining phase relevancy. The key advancement involves mapping the complex quadrature amplitude modulation (QAM) preamble to a quantized phase shift keying (PSK) constellation before application to a matched complex correlator. The proposed process essentially “amplitude normalizes” the input signal without the use or complexity associated with a divider. This simplified normalization scheme makes the packet detection algorithm robust against amplitude variations in the input signal, while still allowing for good correlation output. In applications where interference is superimposed on the I/Q input signals, the invention improves the detection capability over automatic gain control (AGC) normalization methods.

An acquisition and tracking apparatus is provided for tracking digitized spread spectrum navigation signals modulated with a spreading code according to any of a set of modulation types including Binary Phase Shift Keying (BPSK) with and without Frequency Domain Multiplexing Access (FDMA), time multiplexed BPSK, Quadrature Phase Shift Keying (QPSK), sine and cosine Binary Offset Carrier (BOC), modified, complex, and time multiplexed BOC (TMBOC), the apparatus comprising a plurality of universal tracking channels, each coupled to an interrupt module. The universal tracking channel includes a carrier demodulation module, a code generation module, a correlator module, a code frequencies generation module, and a subcarrier combining module for efficiently using the correlator resources in the correlation of the data and the pilot components of the signal within a single universal tracking channel. A corresponding method of operation is also provided.

A method and apparatus for designing a Reference Signal (RS) used by a User Equipment (UE) to obtain respective channel estimates for demodulating respective Physical Downlink Control CHannels (PDCCHs), for determining at a UE a number of resource blocks to include for a reception of a Physical Downlink Shared CHannel (PDSCH), for determining at a UE a RS antenna port in order to enable spatial multiplexing of Enhanced PDCCH (EPDCCH) transmissions to different UEs, and for supporting Quadrature Amplitude Modulation 16 (QAM16) modulation, in addition to Quadrature Phase Shift Keying (QPSK) modulation, for EPDCCH transmissions without increasing a number of decoding operations at a UE are provided.

A method of setting a transport block size for a user equipment in a wireless communications system includes providing a combination table for being looked up to generate a parameter value according to a combination of a modulation scheme and a number of channelization codes indicated by a base station, so as to decide a transport block size index, and configuring a first parameter value corresponding to a least resource usage in the combination table as a first transport block size index before deciding the transport block size index. The first transport block size index is a transport block size index corresponding to a smallest transport block size in a transport block size table, and the combination table and the transport block size table are used when quadrature phase shift keying (QPSK) modulation, 16 quadrature amplitude modulation (16 QAM) or 64 quadrature amplitude modulation (64 QAM) is activated.

A bit interleaver, a bit-interleaved coded modulation (BICM) device and a bit interleaving method are disclosed herein. The bit interleaver includes a first memory, a processor, and a second memory. The first memory stores a low-density parity check (LDPC) codeword having a length of 64800 and a code rate of 7/15. The processor generates an interleaved codeword by interleaving the LDPC codeword on a bit group basis. The size of the bit group corresponds to a parallel factor of the LDPC codeword. The second memory provides the interleaved codeword to a modulator for quadrature phase shift keying (QPSK) modulation.

The invention discloses an all digital frequency converting method and a device thereof, being easily realized for hardware. The method and the device are essentially used for sample rate convertion of rational number-times of baseband signals and the convertion of the baseband signals and the intermediate frequency signals in digital communication. Under the coordination of control signals and enabling signals, the convertion of signal sample rate can be finished and the convertion of the baseband signals and the intermediate signals can be finished through the reasonable matching of variable integral number-times wave filtering and fraction-times interpolation. The system of the invention essentially comprises a frequency mixer, a cascade connection integral comb filter, a fraction-time interpolating device, a half-band filter, a signal shaping filter, a power detection module and a control interface. The configurable hardware implemented structure of the invention is applicable to a plurality of modulation methods, has the advantages of low resource consumption and good portability, and is used for various wireless communication systems such as multilevel phase shift keying (MPSK), orthogonal frequency division multiplex (OFDM), direct sequence spread spectrum (DSSS) and continuous phase modulation (CPM), etc.

A system and method for data communication over a cellular communications network that allows the transmission of digital data over a voice channel using a vocoder that operates in different modes depending upon characteristics of the inputted signal it receives. To prepare the digital data for transmission, one or more carrier signals are encoded with the digital data using one of a number of modulation schemes that utilize differential phase shift keying to give the modulated carrier signal certain periodicity and energy characteristics that allow it to be transmitted by the vocoder at full rate. The modulation schemes include DPSK using either a single or multiple frequency carriers, combined FSK-DPSK modulation, combined ASK-DPSK, as well as PSK with a phase tracker in the demodulator. These modulation schemes permit data communication via a CDMA, GSM, or other type of voice traffic channel at a low bit error rate.

An approach is provided for generating Low Density Parity Check (LDPC) codes. An LDPC encoder generates a short LDPC code by shortening longer mother codes. The short LDPC code has an outer Bose Chaudhuri Hocquenghem (BCH) code. According to another aspect, for an LDPC code with code rate of 3/5 utilizing 8-PSK (Phase Shift Keying) modulation, an interleaver provides for interleaving bits of the output LDPC code by serially writing data associated with the LDPC code column-wise into a table and reading the data row-wise from right to left. The above approach has particular application in digital video broadcast services over satellite.

A universal mobile telecommunications system (UMTS) receiver uses Pilot Symbol Assisted Modulation (PSAM) in demodulating a received Binary Phase Shift Keying (BPSK) signal. The UMTS receiver uses a ratio of the transmitted energy per pilot symbol to the transmitted energy per data symbol as an index into a look-up table to return a value for a scale factor for use in demodulation of the received signal, which provides better performance during periods when the fading distribution is unknown.

There is provided a method for hierarchical modulation relating to a first signal, a second signal, and an original constellation having a plurality of symbols in a non-uniform 8 Phase-Shift-Keying (PSK) configuration. Quadrature-Phase-Shift-Keying (QPSK) modulation is used for the first signal and Binary-Phase-Shift-Keying (BPSK) modulation is used for the second signal. The method includes the step of replacing at least some of the plurality of symbols with at least one radial-type QPSK-BPSK constellation.

An efficient system and method for modulation and demodulation to achieve a high data rate using Bit-Interleaved Coded Modulation and OFDM uses either a coherent or a non-coherent transmission scheme using differential modulation. In order to maintain a high data rate impervious to sudden phase changes, a communication system uses an efficient constellation having multiple rings with different sizes and modulation/demodulation schemes utilizing this constellation. In power line communications, the channel gain information is obtained easily at a receiver (100) while the phase information is not. Thus, the communication system uses an absolute magnitude and differential phase coding for modulation and demodulation of the signals.

Disclosed is a non-equal probability constellation labeling method based on an absolute phase shift keying (APSK) constellation diagram. The non-equal probability constellation labeling method based on the APSK constellation diagram is characterized by comprising the steps that: the APSK constellation diagram is constructed, number of steps of the constellation labeling is M, M=2m, and m is a positive integer, numbers of constellation points on each ring is the same, phase deviations of each ring are also the same; a constellation labeling mode of the APSK constellation diagram is designed, and the constellation labeling mode is enabled to be a gray labeling; the constellation points are grouped, and constellation points on the same ring are combined to be a new constellation point; labeling bits of the prior constellation points on the same ring are distributed to the new constellation point in sequence. According to the non-equal probability constellation labeling method based on the APSK constellation diagram, the inhomogeneous constellation diagram and a non-equal probability labeling technology are adopted, distribution of output signals of the constellation labeling is enabled to be close to Gaussian distribution, shaping gain is achieved, performance of a coded modulation system is improved, and signal to noise ratio in a modulation process is reduced.

The present invention provides an optical phase modulation method using optical frequency shift devices. By accurately controlling the frequency shift, the phase delay experienced by the light signal through an optical medium (fibre, free space, vacuum, or other) can be controlled with high resolution. Hence, phase change can be achieved through frequency change. This technique can be applied to a wide range of applications whenever phase modulation is needed, such as in various phase-shifted keying techniques in optical communications, and in optical metrology. The disclosed phase modulation method can also be used as a phase encoding technique in quantum key distribution.