121 results about "Single carrier modulation" patented technology

A resource block (RB)-based multicarrier modulation (MCM) transmitter and receiver structure for spectral agile systems are disclosed. The transmitter and the receiver are capable of sharing opportunistically available and non-contiguous channels with other users. The RB-MCM partitions the available spectrum, contiguous or non-contiguous, into multiple RBs (same or different sizes), applies a baseband MCM or single carrier modulation, or coded single carrier or multicarrier schemes in each RB with a type of spectral leakage reduction technique, and applies RB modulation for each RB to modulate the signal from baseband to the frequency band of that RB. At the receiver, the received signal may be filtered and RB demodulation may be applied to put each RB signal in baseband and a baseband multicarrier or single carrier or coded single carrier or coded multicarrier demodulation may be applied to each RB signal. Different RBs may use different modulation schemes.

A mixed waveform configuration for wireless communications including a first portion that is modulated according to a single-carrier modulation scheme and a second portion that is modulated according to a multi-carrier modulation scheme. The waveform is specified so that a channel impulse response (CIR) estimate obtainable from the first portion is reusable for acquisition of the second portion. The first portion includes a preamble and header and the second portion typically incorporates the payload.

Multi-band single-carrier modulation. A novel approach is presented by which interference compensation may be performed for signals received by a piconet operable device. The piconet operable device may be implemented within a region that includes two or more SOPs (Simultaneously Operating Piconets). Estimation of the level and location of interference is performed and the input to a decoder (within the piconet operable device) is selectively weighted to ensure that the effect of any existent interference within the signal received by the piconet operable device is minimized. Different interference levels are dealt with differently. For one example, portions of the received signal having undergone a large amount of interference may be simply treated as erasures with respect to the input the decoder. For another example, portions of the received signal having undergone some smaller degree of interference, but some interference nonetheless, may be de-weighted before being provided to the decoder.

A system for Digital Subscriber Line (DSL) data communications, and therefore the transceiver that contains the transmitter and the receiver implementing such system, based on Single Carrier Modulation (SCM). The invention includes an efficient vectoring structure that provides novel solution for crosstalk (505 and 506) elimination in SCM systems, which allows the cooperative operation at the transmitter (511) side as well as at the receiver (512) side.

The present invention also includes a preamble insertion in a specific location of the transmission path, which makes possible the synchronization, direct channel response (503 and 504) estimation, crosstalk channel responses estimation and noise (507 and 508) estimation in agile manner, to make a continuous tracking of the changes of the channel (503 to 506) and the noise environment (505 to 508). It allows operation with low noise margin.

For approaching the capacity of the channel the present invention also defines the blocks that compose the forward error correction and their corresponding location to operate near to the channel capacity limit.

Channel estimation of block signals containing pilot frequency and balanced method characterizes in containing side channels of force and after of a main channel component in a movable window to determine to get a correct channel estimation interval again to get channel impulse response estimation with the length of N, M or M+2XN, then to take position of home and end of the said window as the positioning information needed by circular convolution of the signal and channel inputs response structure and process the data block via channel transmission as the one after channel distortion via frequency domain balance offset or make time-domain over-sampling channel estimation in the sliding window interval to inerase time-domain resolution of channel estimation. The data block can be IDFT of OFDM or modulated by single carrier.

A multiple access technique is described, which is capable of maintaining orthogonality between transmitted signals in multipath conditions, even when part of or all of the transmitted signals belong to the family of Single Carrier modulation. The Single Carrier signals are converted into multicarrier signals which utilize just a fraction of the spectral lines by transmitting each fragment of data several times. The orthogonal multiplexing technique enables transmitters to enjoy both the advantages of OFDMA, such as noninterference between signals, adaptive bandwidth allocation and wideband diversity, and the Peak-to-Average Power Ratio advantage of the single carrier modulation. The multiplexing technique described allows to incorporate in the same multiple access system both OFDM signals and Single Carrier signals.

A method and system for reducing the power to average ratio (PAR) at the transmitter after the up sampling and interpolation filter. In the time domain, Side Tone Packets Injection (STPI) system and method detects the optimal peaks that will result in having a low PAR at a sampling rate of T/K and combines an optimal binary and a PAR-lowering sequence and an upsampled, interpolated original discrete time signal at the scale of one extended symbol for multi-carrier modulation and at the scale M of symbols for single-carrier modulation. STPI does not require peaks search and processing at the scale of many time samples, does not require iterative Fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT) processing thus, allowing the receiver not to perform extra demodulation.

Circularly pulse-shaped waveforms for communication systems are disclosed herein including a single carrier modulation in which pulse-shaping is performed using a circular convolution by the transmitter for various modulation schemes. A transmitter, related method, and corresponding receiver are also disclosed for demodulation of the single carrier circularly pulse-shaped signal and data extraction.

The invention relates to a time- and frequency-domain unified single carrier modulation (TFU-SCM) signal transmission method, and belongs to the technical field of digital information transmission. The method comprises that: information generated by a sending end is subjected to source coding, channel coding and constellation mapping in turn to form mapped information; the mapped information is subjected to time- and frequency-domain unified single carrier modulation FU-SCM modulation, and a plurality of modulated symbols form a frame signal to be sent; the received frame signal is split into a TFU-SCM modulation symbols in a corresponding composition mode; and the modulation symbols are subjected to TFU-SCM demodulation to form serial data, and the serial data is subjected to constellation inverse mapping, channel decoding and source decoding in turn to form the original information. The method maintains the advantage of low complexity of the sending end of the single carrier frequency domain equalization (SC-FDE) technology, the number of UW in the pilot frequency can be flexibly selected according to requirement on system performance, operation such as synchronization, channel estimation, balance and the like can be convenient to carry out at a receiving end by operating the pilot frequency in the frequency domain, the processing efficiency of the system is improved, and the method is more suitable for a broadband wireless mobile communication system.

The invention provides a frequency domain resource allocation method of multi-antenna satellite mobile communication offset single carrier (OSC) modulation, which realizes continuous allocation of frequency domain resources. The method comprises the following steps of: calculating an equivalent signal to interference and noise ratio on each resource block (RB); grouping whole spectrum resources, and calculating the rate sum of each group; calculating the ratio of an instant transmission rate of a user to an average transmission rate, and sorting the ratios of all users in a descending order; selecting u user peak points, wherein u is the number of user transmission; and sorting the instant transmission rates of all users in a descending order, and performing continuous resource allocation for the u users by a greedy algorithm according to the instant transmission rate. According to the method provided by the invention, the multi-antenna satellite mobile communication OSC modulation resource scheduling algorithm can improve the power amplification efficiency of a satellite transmitting end, reduce the A/D (analog/digital) and D/A complexity and improve the throughput rate.

The invention provides a SPWM pulse rotation control method for cascaded neutral-point clamped multilevel inverters, which belongs to the technical field of power electronic multilevel pulse-width modulation. The control method comprises the steps of adopting single-carrier modulation, calculating pulse duty cycle on the basis of formulae, transforming modulation result into a corresponding binary code, evenly applying each inversion unit and two series capacitors in each inversion unit through pulse coding and dynamic pulse rotation, balancing the voltage and power of each inversion unit, balancing the voltage of the two series capacitors in each inversion unit and realizing high pulse frequency of complex phase voltage through low switching frequency of each inversion unit. The control method does not need to add any extra hardware to the cascaded neutral-point clamped multilevel inverters, and a control plate can use one DSP chip and one CPLD chip, wherein the DSP produces the information of the binary code needed by SPWM modulation in the invention, and the CPLD completes pulse coding and pulse rotation. The control method has the advantages of implementation easiness and low system cost.

A single carrier modulation scheme suitable for use in high frequency communication systems is provided that achieves improved residual frequency error and phase noise estimation. At a transmitter, cyclically orthogonal constant amplitude pilot signals are inserted at the beginning (or end) of a plurality of SCBT blocks of a block coded data stream. At a receiver, a phase rotation of the received data stream is determined to remove a residual frequency error or to estimate the phase noise.

The present invention relates to a self-adaptive multi-mode underwater acoustic communication system and method, the method comprises: generating different modulation modes to modulate signals according to spread spectrum and OSDM (orthogonal signal division multiplexing) modulation techniques; wherein a transmitting terminal of the communication system includes a modulation mode selection module,a digital modulation module, a spread spectrum modulation module, an OSDM modulation module, and a data framing module, and a receiving terminal includes a synchronization module, a Doppler compensation module, a channel equalization module, and a modulation mode determination module and corresponding demodulation modules. The system can change self-adaptive signal modulation methods according tochanges of an underwater acoustic channel, and realize free switching of a single-carrier modulation mode and the multi-carrier modulation mode. The self-adaptive multi-mode underwater acoustic communication system has low complexity, strong anti-interference, anti-multipath and anti-Doppler frequency offset, and can effectively solve the problem of unreliable signal transmission caused by underwater multipath, Doppler frequency offset and noise.

A method and system for reducing the power to average ratio (PAR) at the transmitter and after the up sampling and interpolation filter. In the time domain, Fractional Local Peak Detection and Mitigation (FLPDM) locally (i.e. in the neighborhood where the high peak occur) detects the high peaks at a sampling rate of T/K and combines an optimal binary and a PAR-lowering sequence at the scale of one extended symbol for multi-carrier modulation and at the scale M of symbols for single-carrier modulation. Since the technique acts locally, FLPDM does not require peaks search and processing at the scale of many time samples, does not require iterative Fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT) processing and it assures tunable millions of instruction per second (MIPS) performance.

The invention discloses a modulation method of a three-phase Z-source neutral point clamped multi-level photovoltaic inverter. The method comprises the following steps of: obtaining line voltage signals Vac*, Vba* and Vcb* through initial modulating waves Va*, Vb* and Vc* and multiplying by a coefficient K respectively; obtaining a zero sequence signal v0 through a zero sequence signal calculating unit; adding zero-sequence signal with KVac*, KVba* and KVcb* to obtain final modulating waves Va**, Vb**, and Vc**, and comparing the modulating waves Va**, Vb** and Vc** with a carrier wave to obtain logical signals Sa, Sb and Sc; comparing the carrier wave with VH and VL to obtain a through connect signal ST; and making the logical signals Sa, Sb and Sc and the through connect signal ST pass through a logic circuit to obtain a switching signal. The invention has the beneficial effects that a single-carrier-wave modulation method is provided, so that the problem of excessive complexity in realizing the conventional multi-carrier-wave modulation and space vector modulation is solved; and meanwhile, the common-mode voltage of a system is kept constant, so that the drain current of the system is effectively restrained. A switching signal generating circuit is simple in structure, and can be realized by adopting an analog circuit as well as a digital circuit.

The invention discloses a millimeter waves (MMW) indoor communication system capable of flexibly configuring a guard interval and provides a novel data format modulated by a single carrier. A main principle is that a guard interval pseudorandom sequence substitutes for a data cyclic prefix of a conventional single carrier communication system. Compared with the single carrier communication system using the data cyclic prefix, the system using the data format may prevent a transmitting end from caching data blocks so as to reduce data processing time delay at the transmitting end. Further, the pseudorandom sequence is known data and has good correlation so as to be capable of being used for channel tracking estimation, clock error tracking estimation, and carrier error tracking estimation. In addition, guard interval pseudorandom sequences with different lengths are used for guaranteeing high transmission performance and transmission efficiency of the MMW communication system in different communication environments.

The invention provides an optical communication system, which has transmission performance higher than that of a single modulation way. Two modulation formats are multiplexed onto an optical carrier in a polarization multiplexing way to realize the hybrid transmission of the two different modulation formats. A polarization beam splitter splits laser into two paths, wherein one path adopts a single-carrier light modulation technology, and the other path adopts an orthogonal frequency division multiplexing (OFDM) light modulation technology. A polarization light combiner performs polarization multiplexing on modulated signals to finish a transmitter function. The peak-to-average ratio of light spectrums of the hybrid modulated signals is between that of single-carrier modulated signals and that of OFDM modulated signals. In the invention, a receiver selects an advantaged modulation format from the two modulation formats for the key signal processing of electrical dispersion compensation and digital phase compensation, thereby realizing the advantage complementation of the two modulation formats and improving overall system performance.

The invention discloses a multi-antenna transmission system and a multi-antenna transmission method. A transmitter of the system comprises a spatial modulation module, a single-carrier modulation module, a cyclic prefix insertion module, a digital/analogue (D/A) conversion module and a first radio frequency link module. The system is characterized in that: the transmitter also comprises a data distribution module and a first antenna selection module. According to the method, an information bit stream to be transmitted is divided into two paths through data distribution, wherein one path comprises information for controlling serial numbers of antennae, and is directly transmitted to an antenna selection module, and the other path comprises data information bits which are modulated, subjected to radio frequency processing and then transmitted to the antenna selection module; and then an antenna is selected to transmit information. Therefore, compared with the conventional method, the method has the advantages that: the number of radio frequency links is decreased; and system cost is decreased.

The invention consists of a tuner used to down-convert the multimedia signal, an ADC used to convert the down-converted signal from tuner into the digital signal, a demodulator used to demodulate the converted signal from ADC, a deinterleaver used to deinterleave the demodulated signal from the demodulator, and a channel decoder used to decode the deinterleave signal.

The invention discloses a method and a device for detecting SC (single carrier) modulation and OFDM (orthogonal frequency division multiplexing) modulation. The method and the device for detecting the SC modulation and the OFDM modulation are used to quickly distinguish the SC modulation from the OFDM modulation in a system where the SC modulation and the OFDM modulation coexist, and if a data field carried by a physical protocol data unit adopts the OFDM modulation, a transmitting end performs phase rotation operation on a signaling field. After a receiving end performs equilibrium operation, a signal carrier modulation mode is judged by detecting energy of the signaling field, and if a detected result is that the OFDM modulation is adopted, additional inverse phase rotation is performed on the signaling field, and then signaling information is obtained by processing a basic baseband signal. Compared with the prior art, the method for detecting the SC modulation and the OFDM modulation can reduce detection time delay on the premise of not needing additional signaling reminding, facilitates saving of expense of a buffer area, and reduces system complexity and cost.

The digital multimedia signal receiver to treat single/multi-carrier mode comprises: a high-frequency head to receive modulated digital multimedia signal; a ADC to convert the signal from high-frequency head into digital format; a pattern detector to detect the signal from ADC is multi-carrier or single-carrier according to information in the signal; and a demodulation unit to demodulate the digital single/multi-carrier signal from ADC according to recognition information from pattern detector contained PN sequence or/and at least a pilot frequency.