196results about How to "Reduce PAPR" patented technology

In a communications system which complies with LTE including a base station 2 which transmits data by using an OFDM (Orthogonal Frequency Division Multiplexing) method as a downlink access method, and a mobile terminal 3, in a case in which an uplink scheduling request signal SR is transmitted by using an S-RACH when an Ack/Nack signal is being transmitted by using an Ack/Nack exclusive channel, the transmission of the Ack/Nack signal is stopped while the uplink scheduling request signal SR is transmitted.

An apparatus for transmitting data in a frequency division multiple access based communication system is disclosed. The apparatus includes a symbol block generator for generating a symbol block in a predetermined symbol block period within one TTI when control information to be transmitted exists in the TTI, an FFT unit for performing FFT on the symbol block, and an IFFT unit for performing IFFT on signals output from the FFT unit and then transmitting the signals. The symbol block includes the control information and data to be transmitted. The TTI includes multiple symbol block periods.

The invention discloses that based on open IFFT / FFT lower reserved subcarrier OFDM system PAPR methods and devices, and the system is using IFFT / FFT transform to a peak frequency domain Consumers sequence in the transmitter to reduce OFDM system ratio of power PAPR, the method described in steps including data distribution , IFFT transformation, realizing OFDM modulation, gained time-domain signal, judgment threshold and whether the number of iterations is to achieve settings, limited Consumers peak processing, extracted through FFT frequency domain reduce-peak sequence. The installations include the transmitter and receiver, the transmitter unit increased data distribution, data option modules, judgment unit, a unit reduce-peak sequence, sequence reduce-peak insert modules; Receiver increased information extraction unit. This invention in a process of elimination-series will not lead to the increase in bit error rate, the effect of significantly reducing the PAPR, the device is simple, running FFT / IFFT the iteration times is less.

One disclosure of the present specification provides a method for mapping data symbols in a wireless communication system. The method comprises the steps of: generating a first symbol sequence in which first symbols among data symbols to be transmitted are consecutively arranged; generating a second symbol sequence in which second symbols among the data symbols are consecutively arranged; and performing modulation of the first and second symbol sequences, wherein the step of performing modulation may be a phase rotation on the boundary of the first symbol sequence and the second symbol sequence.

An apparatus and method for PAPR reduction in a wireless communication system are provided. In the PAPR reducing apparatus, a first calculator calculates an ISF for each sample of baseband sample data. A successive peak detector adjusts the ISF of the each sample according to the spacing between successive peak samples. A second calculator subtracts the ISF of each sample received from the successive peak detector from a predetermined value. A window convolution calculator calculates a convolution of the difference received from the second calculator and a predetermined window function, and outputs a window operation value of each sample.

A base station apparatus in a radio communications system is disclosed. The base station apparatus communicates with a mobile station using an OFDM scheme in downlink. The base station apparatus includes a sync signal generating unit which generates a secondary sync channel; a multiplying unit which multiplies a scramble code with the secondary sync channel; and a transmitting unit which transmits the secondary sync channel with which the scramble code is multiplied. Cell-specific information is detected by the secondary sync channel.

A method and apparatus for reducing a Peak to Average Power Ratio (PAPR) in a digital broadcasting system are provided. Reserved tones are determined, and the determined reserved tones are used to transmit a signal having an impulse characteristic in locations of sub-carriers that do not collide with a pilot signal of a preamble in a frame. The signal having the impulse characteristic is transmitted through the reserved tones in a symbol interval for which the preamble is transmitted.

An apparatus and method for reducing a Peak-to-Average Power Ratio (PAPR) are provided. The apparatus includes a gain processor for multiplying time signals in paths by gains set for respective paths, a delay processor for delaying gain-multiplied signals in second to last paths except for a first path by time delays set for respective second to last paths, a summer for summing the gain-multiplied signal for the first path received from the gain processor and the delayed signals received from the delay processor, a PAPR processor for measuring a PAPR of the summed signal received from the summer, for comparing the measured PAPR with a target PAPR, and for requesting one or more changes of at least one of the gain and time delay of each path, and a gain delay controller for changing the at least one of the gain and the time delay of each path according to the request received from the PAPR processor and for controlling the gain processor and the delay processor according to the change.

A broadband wireless communication system is provided. A transmitting end of the broadband wireless communication system includes: a controller for receiving a plurality of Orthogonal Frequency Division Multiple Access (OFDMA) symbols, and for generating the same number of symbol sets corresponding to the OFDMA symbols wherein each symbol set includes a plurality of OFDMA symbols having various Peak to Average Power Ratios (PAPRs) according to several phase-shifting patterns, a selector for grouping the plurality of OFDMA symbols into symbol groups according to the same phase-shifting pattern of the several phase-shifting patterns, and for finding maximum peak value in each symbol group, and a transmitter for transmitting the symbol group having a minimum value selected from among the maximum peak values of the symbol groups.

A method for reducing the peak-to-average power ratio of the time-domain signal in a communication system using multi-carrier modulation is provided herein. The present invention is based on the method of recursive clipping and filtering to reduce the peak-to-average power ratio and out-of-band spectrum, but during the recursive process, the distortion of the multi-carrier modulated signal is controlled to be bounded within a specific region. In an additive white Gaussian noise channel with high signal-to-noise ratio, the present invention could achieve significantly lower error rate and the error floor phenomenon is almost completely removed. Therefore the power amplifier could be operated at higher average output power and a smaller range of linearity.

A method for generating candidate used in TCOFDM (turbo coded orthogonal frequency-division multiplexing) with SLM (selective mapping) technique, a user data is combined with a plurality of seeds to generate corresponding a plurality of message vectors. The method is characterized in performing tail-biting turbo encoding on the message vectors to generate corresponding turbo codewords used for generating candidates, and the seed of each message vector is different from the seeds of other message vectors.

The invention relates to a peak to average power ratio (PAPR) restraint method, comprising the following steps: A. multiplying X1 and X2 by an identical random sequence respectively in a first symbol period to calculate PAPR respectively, recording as PAPR [X1] and PAPR [X2], and selecting a random sequence from a set; B. comparing PAPR [X1] and PAPR [X2] and selecting the maximum value as PAPR (X); C. repeating the steps above, selecting a signal X1* and a signal X2* with minimum PAPR (X), and selecting a corresponding random vector; D. repeating the steps above until the last symbol of the antenna; and E. processing all symbols with a compandor to reduce PAPR again. Based on study of PAPR reduction methods, the invention provides the PAPR restraint method and a system thereof for a multi-antenna LTE system and has much better PAPR reduction capacity than the PAPR reduction capacity of separate SLM method and companding method.

An apparatus for transmitting data in a wireless communication system is provided. The apparatus includes a data processor for generating modulation symbols by coding information bits and by constellation-mapping the coded information bits, a transmission (TX) processor for generating transmission symbols by applying any one of first and second transmission diversity schemes to the modulation symbols and for configuring a subframe including the transmission symbols, and a plurality of antennas for transmitting the subframe. The subframe comprises a plurality of slots and has a varying frequency band every slot by frequency hopping.

Disclosed is an apparatus and method for reducing a peak-to-average power ratio (PAPR) due to multiple subcarriers in an OFDM (Orthogonal Frequency Division Multiplexing) mobile communication system. In the OFDM mobile communication system, a transmitter pre-emphasizes an output signal of an IFFT (Inverse Fast Fourier Transform) block, and a receiver de-emphasizes a received signal before FFT (Fast Fourier Transform), thereby efficiently reducing PAPR due to multiple subcarriers.

A method of processing an Orthogonal Frequency-Division Multiplex (OFDM) signal having a plurality of data carriers and a plurality of unused carriers is disclosed. The method comprises transforming an original frequency-domain OFDM signal into a time domain signal and simulating the effect of a non-linear amplifier on the time-domain signal to provide a potentially distorted time domain signal. The potentially distorted time domain signal is transformed into a potentially distorted frequency domain signal and at least some of any values of the data carriers in the potentially distorted frequency domain signal are restored with corresponding values from the original frequency domain signal. At least some of the unused carriers in the at least partially restored frequency domain signal are scaled with a scaling factor. The scaled frequency domain signal is transformed into a temporary time domain signal and the temporary time domain signal is analysed for the presence of a peak or near zero amplitude value that would lead to distortion by said amplifier. If the signal includes such a peak or near zero value, the scaling, transforming and analysing are repeated with an increased scaling factor.

A transmitter includes a first limiter for performing a first clipping in which an amplitude part at a level higher than an amplitude level based on a first clipping level is cut out from an input signal to be subjected to power amplification, a second limiter for performing a second clipping in which an amplitude part at a level lower than the amplitude level based on a second clipping level is cut out from a first signal that has undergone the first clipping, a separation section for separating a second signal that has undergone the second clipping into an amplitude modulated part and a constant amplitude part, a first amplifier for amplifying the amplitude modulated part, a second amplifier for amplifying the constant amplitude part, and a combiner for outputting a third signal obtained by combining the amplitude part amplified by the first amplifier and the constant amplitude part amplified by the second amplifier.

A sinusoidal wave output from an RF oscillator provided in a transmitter is phase-modulated using a baseband OFDM signal output from a transmitter-signal processing unit 100, and this phase-modulated sinusoidal wave is used to modulate an optical wave. Using this light as signal light to achieve optical communication enables a low PAPR value such as 6 dB or less to be achieved where the photoelectric power is high in an optical fiber, thus enabling the above described problems to be solved. This signal light travels through an optical fiber serving as the transmission line and is converted by a receiver into an electric signal. The electric signal is synchronously detected using a sinusoidal wave output from an RF oscillator oscillating at the same frequency as the above RF oscillator provided in the transmitter. Ordinary OFDM signal processing for reception is performed.

A method and system of transmitting a plurality of Orthogonal Frequency Division Multiple (OFDM) symbols in a block transmission system of a communication network is provided. The block transmission system is a frequency reuse system. The method includes encoding the plurality of OFDM symbols. The method further includes, modulating at least one of a phase and a magnitude of the plurality of OFDM symbols. Thereafter, a plurality of modulated OFDM symbols is converted from a digital form to an analog form. The plurality of modulated OFDM symbols corresponds to the plurality of OFDM symbols.

The invention discloses an impulse waveform modulation method based on a multi-dimensional constellation diagram. The method enables modulation data to be mapped into points in the multi-dimensional constellation diagram and loaded on multi-channel orthogonal pulses, and all the multi-channel orthogonal pulses enter channels to be transmitted after being superimposed in a time domain. After a receiving end achieves synchronization, the multi-channel orthogonal pulses generated locally are used for respectively carrying out correlation with received signals, time domain orthogonality among the pulses is used for achieving modulation information separation of the orthogonal pulses, received constellation points are obtained, and received data are obtained through utilization of a maximum likelihood decision. Compared with a traditional two-dimensional constellation diagram modulation base on sine waves, under the conditions of identical bandwidth using efficiency and the identical error rate, the modulation method needs lower signal to noise ratio.