Carrier Interferometry (CI) provides wideband transmission protocols with frequency-band selectivity to improve interference rejection, reduce multipath fading, and enable operation across non-continuous frequency bands. Direct-sequence protocols, such as DS-CDMA, are provided with CI to greatly improve performance and reduce transceiver complexity. CI introduces families of orthogonal polyphase codes that can be used for channel coding, spreading, and/or multiple access. Unlike conventional DS-CDMA, CI coding is not necessary for energy spreading because a set of CI carriers has an inherently wide aggregate bandwidth. Instead, CI codes are used for channelization, energy smoothing in the frequency domain, and interference suppression. CI-based ultra-wideband protocols are implemented via frequency-domain processing to reduce synchronization problems, transceiver complexity, and poor multipath performance of conventional ultra-wideband systems. CI allows wideband protocols to be implemented with space-frequency processing and other array-processing techniques to provide either or both diversity combining and sub-space processing. CI also enables spatial processing without antenna arrays. Even the bandwidth efficiency of multicarrier protocols is greatly enhanced with CI. CI-based wavelets avoid time and frequency resolution trade-offs associated with conventional wavelet processing. CI-based Fourier transforms eliminate all multiplications, which greatly simplifies multi-frequency processing. The quantum-wave principles of CI improve all types of baseband and radio processing.

Multicarrier sub-layer for direct sequence channel and multiple-access coding

Techniques to implement MBMS services in a wireless communication system. In one aspect, a method is provided for processing data for transmission to a plurality of terminals. Frames of information bits (which may have variable rates) are provided to a buffer implementing a matrix. The matrix is padded with padding bits based on a particular padding scheme to support variable frame rates. The frames are then coded based on a particular block code to provide parity bits. The frame of information bits and the parity bits are then transmitted to the terminals. In another aspect, a method is provided for controlling the transmit power of a data transmission to a plurality of terminals. In accordance with the method, TPC streams are received from the terminals and processed to obtain a stream of joint power control commands used to adjust the transmit power of the data transmission.

Multi-media broadcast and multicast service (MBMS) in a wireless communication system

A method and apparatus for allocating subcarriers in an orthogonal frequency division multiple access (OFDMA) system is described. In one embodiment, the method comprises allocating at least one diversity cluster of subcarriers to a first subscriber and allocating at least one coherence cluster to a second subscriber.

Ofdma with adaptive subcarrier-cluster configuration and selective loading

A method and apparatus achieves rapid timing synchronization, carrier frequency synchronization, and sampling rate synchronization of a receiver to an orthogonal frequency division multiplexed (OFDM) signal. The method uses two OFDM training symbols to obtain full synchronization in less than two data frames. A first OFDM training symbol has only even-numbered sub-carriers, and substantially no odd-numbered sub-carriers, an arrangement that results in half-symbol symmetry. A second OFDM training symbol has even-numbered sub-carriers differentially modulated relative to those of the first OFDM training symbol by a predetermined sequence. Synchronization is achieved by computing metrics which utilize the unique properties of these two OFDM training symbols. Timing synchronization is determined by computing a timing metric which recognizes the half-symbol symmetry of the first OPDM training symbol. Carrier frequency offset estimation is performed in using the timing metric as well as a carrier frequency offset metric which peaks at the correct value of carrier frequency offset. Sampling rate offset estimation is performed by evaluating the slope of the locus of points of phase rotation due to sampling rate offset as a function of sub-carrier frequency number.

Timing and frequency synchronization of OFDM signals

A method and apparatus are provided for performing acquisition, synchronization and cell selection within an MIMO-OFDM communication system. A coarse synchronization is performed to determine a searching window. A fine synchronization is then performed by measuring correlations between subsets of signal samples, whose first signal sample lies within the searching window, and known values. The correlations are performed in the frequency domain of the received signal. In a multiple-output OFDM system, each antenna of the OFDM transmitter has a unique known value. The known value is transmitted as pairs of consecutive pilot symbols, each pair of pilot symbols being transmitted at the same subset of sub-carrier frequencies within the OFDM frame.

System access and synchronization methods for mimo ofdm communications systems and physical layer packet and preamble design

A digital signal transmission using OFDM modulation scheme in which the valid transmission data can be reproduced without requiring a recovery of the carriers at a receiver side. On a transmitter side, the transmission data sequence in which predetermined reference data for each carrier are placed among valid transmission data is modulated according to an orthogonal frequency division multiplexing (OFDM) modulation scheme using a plurality of carriers and obtained OFDM transmission signals are transmitted. On a receiver side, the received OFDM transmission signals are demodulated to obtain received data sequence containing valid received data and received reference data, and the valid transmission data are estimated from the received data sequence according to the valid received data, the received reference data, and the predetermined reference data for each carrier.

Method and apparatus for digital signal transmission using orthogonal frequency division multiplexing

Received OFDM signals are transformed from a time domain into a frequency domain by Fourier transformation (12) to generate a vector sequence of each carrier wave in the frequency domain. Necessary dispersion pilot signals and termination pilot signals are extracted (13) from the vector sequence and divided (15) by a modulation complex vector to estimate transmission line characteristics relative to the dispersion/termination pilot signals, and the transmission line characteristics are interpolated (16) to estimate transmission line characteristics relative to the information transmission carrier wave of a synchronous detection segment. The vector sequence is delayed (17) by one symbol. The interpolation output is selected (18) in the case of the synchronous detection segment, and the delay output is selected (18) in the case of a differential detection segment. The vector sequence is divided (19) by the selected output, and the result is subjected to synchronous detection or differential detection and demodulated (20) to generate digital information. Thus, high quality demodulation and demodulation suitable for mobile reception are realized.

Orthogonal frequency-division multiplex transmission system, and its transmitter and receiver

Method and apparatus for transmitting an information signal generate a plurality of block signals on the basis of the information signal, generate a plurality of parity block signals on the basis of the plural data block signals, generate a frame signal containing the plural data block signals and the parity block signals, and send out the frame signal. Each of the data block signals includes a first block synchronizing signal indicating the start of the data block signal, a data signal containing the information signal and a first parity signal derived by encoding the data signal. Each of the parity block signals incudes a second block synchronizing signal indicating the start of the parity block signal, a second parity signal and a third parity signal. Bit signals located at same bit positions in the respective second parity signals are derived by encoding bit signals located at the same positions in the respective data signals. Bit signals located at same bit positions in the respective third parity signals are derived by encoding the bit signals located at the same bit positions in the respective first parity signals or alternatively the third parity signal in each parity block signal is derived by encoding the second parity signal in each parity block signal.

Methods and apparatuses for transmission and reception of information signals

PROBLEM TO BE SOLVED: To provide a retransmitter capable of reducing bandwidth when a digital broadcast signal is retransmitted. SOLUTION: An apparatus 10 which receives digital broadcast signals comprised of a plurality of segments from a plurality of broadcasting stations and transmits an ISDB-T signal on the basis of the received signals, is provided with a plurality of receiving parts 200 for receiving digital broadcast signals by channels; a carrier selection circuit 203 for selecting at least one of segments in the received digital broadcast signals, by channels, on the basis of a preset segment number; a segment delay control circuit 301 for carrying out synchronization of selected signals; a carrier symbol composition circuit 303 for converting phases of carriers constituting a synchronized segment by channels and connecting a plurality of phase-converted carriers; and a transmission conversion circuit 305 for transmitting a connected signal from a predetermined channel that is different from the channel. COPYRIGHT: (C)2006,JPO&NCIPI

Digital broadcast signal retransmitter

PURPOSE:To send each OFDM modulation signal at a maximum bit rate per a transmission frequency band by allocating a transmission band in a form that an adjacent spectrum is in contact with spectrums of each OFDM modulation signal and locking a symbol clock phase. CONSTITUTION:At first frequency intervals DELTAf1, DELTAf2 of a carrier of 1st and 2nd OFDM modulation signals are set equal. An interval fbfa between a maximum carrier frequency fa of a 1st signal and a minimum carrier frequency fb of a 2nd signal is selected to be an integral multiple of DELTAf=DELTAf1=DELTAf2. A symbol clock phase of a 1st OFDM modulation signal and that of a 2nd OFDM modulation signal are locked to each other thereby making ideally symbol switching position of the both coincident with each other. Then the setting above is made to set a value N of NDELTAf=fb-fa to be an integer being one or over, then a DFT window applied discrete Fourier transformation to the 1st and 2nd OFDM modulation signals, then the relation of the 1st and 2nd OFDM modulation signals is set to be a relation as shown in figure. Thus, no interference disturbance is caused between them.

Masayuki Takada

Papers

Method and apparatus for digital signal transmission using orthogonal frequency division multiplexing

Orthogonal frequency-division multiplex transmission system, and its transmitter and receiver

Methods and apparatuses for transmission and reception of information signals

Digital broadcast signal retransmitter

Orthogonal frequency division multiplex modulation signal transmission system