Abstract: When performing data communication with a second wireless communication apparatus having a plurality of antennas by using a plurality of transmission channels formed by spatial multiplexing, a first wireless communication apparatus having a plurality of antennas determines whether the second wireless communication apparatus is capable of communication using the plurality of transmission channels, and, on the basis of the determination result, executes a calibration process of forming the plurality of transmission channels with respect to the second wireless communication apparatus.

Abstract: A phase correcting apparatus, for a radio transmitter which obtains a first radio signal (RS1) based on a first baseband signal (BB1), includes a demodulator which demodulates a feedback signal from which a part of RS1 is extracted by a first carrier signal (CS1) and which generates a second baseband signal (BB2), a modulator which modulates a difference signal between BB1 and BB2 by a second carrier signal (CS2) and which outputs a second radio signal (RS2), a power amplifier which amplifies RS2 to obtain RS1, a detector which detects a phase difference between BB1 and BB2, and a phase rotator which rotates any phase of BB1, BB2, CS1, or CS2 as a target phase correction amount, wherein the detector converts a desired analog signal obtained by multiplying BB1 and BB2 into a digital signal, and which detects the phase difference based on digital data.

Abstract: The present invention proposes an LTE eNodeB receiver channel estimation technique that is referred to as reduced complexity minimum mean squared error (MMSE) technique for channel estimation. From the invention's assumptions, estimations and modified calculations, the present invention generates precise channel estimates of RS using the reduced complexity MMSE matrix and previously computed LS channel estimates HLS is as follows: (Formula I) which generates precise channel estimates of RS using the reduced complexity MMSE matrix and previously computed LS channel estimates. As a second aspect of the present invention, it is desired that the SNR be estimated within ?3 dB of the actual channel SNR. As a third aspect of the invention, an adaptive method of data channel interpolation from RS channel is being proposed in this invention.

Abstract: Symbol detection and soft dempapping methods and systems are provided. Individual subset symbol detection according to an embodiment of the invention involves identifying a search subset of a transmission symbol set for a transmission symbol. For each other transmission symbol in communication signals, multiple search subsets of the transmission symbol set are identified. The multiple search subsets include respective search subsets based on each transmission symbol in either the search subset for the first identified one of the transmission symbols or each of the multiple search subsets identified for a different one of the other transmission symbols. Symbol detection errors may be detected by identifying competing symbols and computing competing distances. Soft demapping may be provided by calculating soft decision results based on detected symbols and weighting the soft decision result.

Abstract: Provided are a radio transmission device and a radio transmission method capable of improving downlink and uplink throughput even when performing dynamic symbol allocation. In the device and the method, BS and MS share a table correlating a basic TF as a combination of parameters such as TB size used for transmitting only user data, an allocation RB quantity, a modulation method, and an encoding ratio, with a derived TF having user data of different TB size by combining L1/L2 control information. Even when multiplexing L1/L2 control information, Index corresponding to the basic TF is reported from BS to MS.

Abstract: An apparatus for receiving signals includes a receiver for receiving a time domain signal from a transmitter, wherein at least one first information bit is mapped, resulting in at least one first mapped symbol; at least one second information bit is mapped, resulting in at least one second mapped symbol; the at least one second mapped symbol is multiplied by at least one third information bit; and the time domain signal is generated from the at least one first mapped symbol and the at least one second mapped symbol.

Abstract: A soft-in-soft-out (SISO) decoder for a general block code includes a source bit generator which generates k guessed source bits; a channel encoder which maps the k guessed source bits to an n-bit channel codeword; a QAM symbol mapper which generates a locally generated symbol sequence comprising m consecutive QAM symbols based on the n-bit channel codeword; a correlator which receives a symbol sequence, a channel state information sequence, and the locally generated symbol sequence to calculate a correlation associated with the received symbol sequence based on the received symbol sequence, the channel state information sequence, and the locally generated symbol sequence; and a log-likelihood ratio calculator which is connected to the source bit generator and the correlator to thereby calculate the required log-likelihood ratios associated with all coded bits corresponding to the received symbol sequence.

Abstract: At a node of a wireless network, equalization operations performed on signals received from a transmitter are adaptively switched to be equalized by an iterative turbo receiver or a linear receiver. A theoretical expression of a post-equalization SINR of a capacity-achieving receiver is used to estimate the post-equalization SINR performance of the turbo receiver. The estimated post-equalization SINR performance is then used as a basis to determine whether the received signal is to be equalized by the turbo receiver or the linear receiver.

Abstract: Systems and methods for generating OFDM signals are provided in which sub-carrier usage is selected and/or remapped in various manners. For example, in some embodiments remapping using a security sequence is employed; in other embodiments, decoy sub-carriers are employed; in other embodiments, mask sub-carriers are used to cover jammed portions of a channel.

Abstract: A device of dynamic communication of information allows, on the average, non-integer bits per symbol transmission, using a compact code set or a partial response decoding receiver. A stream of selectable predetermined integer bits, e.g., k or k+1 data bits, is grouped into a selectable integer number of bit vectors which then are mapped onto corresponding signal constellations forming transmission symbols. Two or more symbols can be grouped and further encoded, so that a symbol is spread across the two or more symbols being communicated. Sequence estimation using, for example, maximum likelihood techniques, as informed by noise estimates relative to the received signal. Each branch metric in computing the path metric of a considered sequence at the receiver is weighted by the inverse of the noise power. It is desirable that the constellation selection, sequence estimation and noise estimation be performed continuously and dynamically.

Abstract: A device may be capable of communicating using at least two type types of modulation methods. Methods and systems are provided for communication of data according to a communications method in which a master transceiver communicates with one or more slave transceivers according to a master/slave relationship. A first data message may include first information and second information that are modulated according to a first modulation method. The second information may include lower data rate data. A second data message may include third information that may be modulated according to the first modulation method and that may indicate an impending change to a second modulation method. The second modulation method may be used for transmitting fourth information, and the fourth information may be included in the second message. The fourth information may include higher data rate data, for example Internet access data.

Abstract: A method and apparatus for performing calculations relating to the derivation of log-likelihood ratio (LLR) is provided. Coefficients in the use of deriving LLRs are calculated the calculation being applicable to any one of a plurality of constellation diagrams (PAM, QAM, PSK). The coefficients may be stored in a table of coefficients, the table corresponding to a particular constellation diagram and modulation scheme. A number of tables may be stored, each table corresponding to a particular modulation scheme. The coefficients are related to a symbol estimated to be closest to the received sample and the closest symbol to the estimated symbol having a complementary value for a bit for which the LLR is to be calculated. Certain coefficients or parts of coefficients may be omitted where the corresponding constellation diagram has symmetries.

Abstract: Peak power is reduced without causing degradation of EVM. A multi-carrier transmission apparatus comprises: a first amplitude suppression unit suppressing amplitude of an oversampled multi-carrier signal; a first Fourier transform unit transforming an output signal of the first amplitude suppression unit into a frequency domain; a first signal suppression unit suppressing a signal outside a band of the output signal from the first Fourier transform unit under a predetermined condition; and a first inverse Fourier transform unit receiving a multi-carrier signal with respect to a signal within the band, receiving the output signal of the first signal suppression unit with respect to a signal outside the band, and inverse Fourier transforming these received signals.

Abstract: A signal demultiplexing method and apparatus are provided, for determining a likelihood of each bit included in a second signal, which is spatially multiplexed with and received with a first signal, based on a maximum likelihood detection (MLD) method using QR decomposition, wherein the first signal excludes the second signal to be calculated only in a final stage of the MLD method.

Abstract: A mechanism for jointly correcting carrier phase and carrier frequency errors in a demodulated signal. A computer system may receive samples of a baseband input signal (resulting from QAM demodulation). The computer system may compute values of a cost function J over a grid in a 2D angle-frequency space. A cost function value J(?,?) is computed for each point (?,?) in the grid by (a) applying a phase adjustment of angle ? and a frequency adjustment of frequency ? to the input signal; (b) performing one or more iterations of the K-means algorithm on the samples of the adjusted signal; (c) generated a sum on each K-means cluster; and (d) adding the sums. The point (?e,?e) in the 2D angle-frequency space that minimizes the cost function J serves an estimate for the carrier phase error and carrier frequency error. The estimated errors may be used to correct the input signal.

Abstract: A method and apparatus for aligning I- and Q-signals in a quadrature receiver based on an squared signal. A correction is evaluated in an iterative manner by finding an average of the squared signal. The average squared signal may be the received signal, in which case the iterations are applied in a feed forward manner. Alternatively, the average squared signal is the aligned signal in which case the iterations are applied in a feed back manner. The correction may include the evaluation of an normalization or, in the feed back case, this can be implicitly included in the manner in which the iteration is applied. Various parameters to the iteration can be set to accommodate the operating environment of the receiver and characteristics of the received signal.

Abstract: Embodiments of the present invention provide systems, devices and methods for modeling and correcting amplitude and quadrature phase errors generated within analog components of a receiver. A frequency-dependent correction method is employed that closely tracks the frequency dependent nature of the mismatch between the I and Q polyphase filter responses. In particular, digital correction is performed on a signal based on a modeled error function generated during a calibration of the receiver.

Abstract: A multiple-input multiple-output multi-band OFDM transmission system (400) employs a data interleaving arrangement that is backwards compatible with specifications for a legacy interleaver. In one embodiment, an input data stream is parsed into two or more separate data streams by a round robin parser (310) and each of the separate data streams is shifted by a corresponding number of symbols and then interleaved by a legacy interleaver (340i). In another embodiment, data for a plurality (N*i) of symbols is split into N sequential groups of data, each group corresponding to one of N MIMO spatial streams, each stream including data for i symbols. Each group is then interleaved by a legacy interleaver (520i). In a third embodiment, an input data stream is interleaved by a scaled version of the legacy interleaver (610), and then parsed by a round-robin parser (620).

Abstract: An apparatus and method for receiving signals in a multiple-input, multiple-output (MIMO) wireless communication system is provided. A receiving end using as many as N Receive (Rx) antennas includes a first detector, as many as (N?2) nth detectors, and an Nth detector. A signal detection technique of the present invention has a low complexity and a throughput similar to that of a Maximum Likelihood (ML) scheme in a Multiple-Input Multiple-Output (MIMO) wireless communication system using a Spatial Multiplexing (SM) scheme.

Abstract: A system and method for employing a six-bit rank 1 codebook for four transmit antennas is provided. A method for communications device operation includes estimating a communications channel between the communications device and a controller serving the communications device, thereby producing a channel estimate, quantizing the channel estimate using a codebook, thereby producing a selected codeword, and transmitting an index corresponding to the selected codeword from the codebook to the controller. The codebook includes a plurality of first level codewords, and each first level codeword includes a plurality of subsidiary codewords.

Abstract: Systems and methods are described that may be used to detect and correct carrier phase offset in a signal. A phase offset corrector receives an equalized signal representative of a quadrature amplitude modulated signal and derives a phase-corrected signal from the equalized signal. The equalized signal is sliced to obtain real and imaginary sequences and a frame synchronizer performs a correlation of the real and imaginary sequences with corresponding parts of a stored frame-sync pseudo-random sequence. Phase correction is based on the maximum real and imaginary values of the correlation. The signal is typically quadrature amplitude modulated signal is modulated using punctured trellis codes. Quadrature phase shift keying modulation, 16-QAM, 64-QAM and other QAM schemes may be used.

Abstract: A multiple-input and multiple-output (MIMO) transmission apparatus includes a modulation signal generating section and a MIMO transmitting section. The modulation signal generating section generates: (i) a first OFDM modulation signal, in which a plurality of subcarriers include a subcarrier carrying a pilot symbol and a subcarrier carrying a data symbol, in both a first time period and a second time period; and (ii) a second OFDM modulation signal, in which the plurality of subcarriers include a subcarrier carrying a pilot symbol and a subcarrier carrying a data symbol in the first time period, while in the second time period an in-phase component and a quadrature-phase component of every subcarrier included in the plurality of subcarriers are zero. The MIMO transmitting section transmits the first OFDM modulation signal from a first antenna and transmits the second OFDM modulation signal from a second antenna.

Abstract: A system for compensating for in-phase and quadrature (I/Q) imbalances for multiple antenna systems (MAS) with multi-user (MU) transmissions (defined with the acronym MU-MAS), such as distributed-input distributed-output (DIDO) communication systems, comprising multicarrier modulation, such as orthogonal frequency division multiplexing (OFDM).

Abstract: A square array of signal points forming a 22n-QAM signal constellation, where n=3, 4, is modified by relocating the inner most 22n/16 and outer 22n/16 constellation points to specific positions, resulting a modified-square constellation with a reduced peak to average power ratio (PAPR) at the modulator output relative to that of the square constellation while resulting in a receiver sensitivity that is degraded by less than the decrease in the modulator's PAPR and hence less than the possible improvement at the transmitter in average transmitted power.

Abstract: Provided is a multi-antenna transmission device (400) which can perform MLD by using a simple configuration of a reception device in a MIMO-AMC system. The multi-antenna transmission device (400) includes common signal point mapping units (401, 402) for mapping data transmitted from different antennas (111, 112) in transmission scheme using MIMO spatial multiplexing, to common signal points shared by respective modulation methods. Thus, the arrangement of baseband signal points obtained by mapping a code word after channel encoding onto an IQ plane can be shared as common signal points shared by modulation methods. Accordingly, the reception device need not prepare a particular circuit for performing MLD calculation in accordance with a combination of the methods for modulating the signals which have been MIMO-space multiplexed. This can reduce the circuit size of the MLD calculation circuit.

Abstract: The present invention discloses a transmission method and apparatus for a wireless communication system. The data transmission method comprises the following steps. A first data mapped in a QAM constellation pattern is transmitted in a first transmission. And a second data, which is reversion of the first data and mapped in said QAM constellation pattern, is retransmitted. In embodiment, the interleaved data is partially swapped based on a predetermined swapping pattern. In another embodiment, first interleaved data and second interleaved data are multiplexed per N bits, N is an integer larger than 1. Therefore, improvement of reliability at first transmission or retransmission in a wireless communication system can be achieved.

Abstract: A system and method for encoding information is disclosed. In one embodiment, information is encoded using a high protection code for the least significant bit and a low protection code for the next three most significant bits. The remaining bits are uncoded. The high protection code may be a turbo code and the low protection code may be a trellis coded modulation code. In this embodiment, the collection of bits is then mapped according to a diagonally shifted QAM constellation technique.

Abstract: Communication systems are described that use geometrically shaped constellations that have increased capacity compared to conventional constellations operating within a similar SNR band. In several embodiments, the geometrically shaped is optimized based upon a capacity measure such as parallel decoding capacity or joint capacity. In many embodiments, a capacity optimized geometrically shaped constellation can be used to replace a conventional constellation as part of a firmware upgrade to transmitters and receivers within a communication system. In a number of embodiments, the geometrically shaped constellation is optimized for an Additive White Gaussian Noise channel or a fading channel. In numerous embodiments, the communication uses adaptive rate encoding and the location of points within the geometrically shaped constellation changes as the code rate changes.

Abstract: A wireless communications device having a complex vector quantization codebook for use in a downlink multi-user MIMO (multiple-input-multiple-output) mobile broadcast system with feedback enables the interference between data simultaneously sent by the base station to a plurality of mobile terminals to be reliably minimized. The codebook contains many subsets of code vectors that are substantially mutually (i.e., pairwise) orthogonal, or almost orthogonal, to each other. With use of such a codebook, a base station can transmit simultaneously to subsets of mobile terminals associated with these subsets of code vectors with minimal interference therebetween.

Abstract: Disclosed are a Time Division Multiplexing (TDM) communication system with a parallel structure and a method for the same. A transmission apparatus of the TDM communication system with the parallel structure includes a Time Division Demultiplexer (TDDM) to perform time division demultiplexing of inputted first serial signals to thereby output the demultiplexed serial signals as a plurality of parallel signals, a plurality of modulators to respectively modulate the outputted parallel signals; a Time Division Multiplexer (TDM) to adjust a multiplexing ratio according to channel-related information, and to perform time division multiplexing of each of the modulated parallel signals in the adjusted multiplexing ratio to thereby output the multiplexed parallel signals as second serial signals, and a transmission antenna to transmit the outputted second serial signals.

Abstract: A method and system for processing LLRs, in a receiver, of transmissions over a wireless telecommunication system, the method including receiving multiple soft symbols, selecting a set of appropriate instructions for LLR calculation for the soft symbols, arranging the soft symbols in a register of a processor according to the selected instructions, selecting an appropriate single instruction from the set of instructions to be implemented by the processor using the soft symbols in the register as operands, and calculating, by a computation unit, multiple LLR values for the multiple soft symbols, in parallel, by means of the selected instruction.

Abstract: A quadrature demodulator preweights an input signal prior to mixing with in-phase and quadrature clock signals. In an implementation with discrete phase rotation, a series of weighting circuits may be arranged before or after a select circuit to select the amount of phase rotation. Various implementations may include ratioed current mirrors to perform the weighting function, a stacked arrangement of mixers, an H-bridge input stage, integrated mixers and select circuits, and/or selectable gain stages such as gm cells to perform the weighting function.

Abstract: A method for transmitting a signal from a transmitter over a channel to a receiver on a Power Line Network, wherein said signal is OFDM-modulated on a set of sub-carriers, is proposed, wherein an OFDM tonemap and an eigenbeamforming encoding matrix are determined based on a channel estimation for each sub-carrier, a tonemap feedback signal and an eigenbeamforming feedback signal are generated, which are descriptive of said OFDM tonemap and said eigenbeamforming encoding matrix, respectively, and transmitted to the transmitter. A corresponding receiver, a transmitter, a power line communication and a power line communication system are described as well.

Abstract: The present invention relates to a digital clipping method for reducing a high peak-to-average power ratio (PAPR) of a transmission signal in a transmitter of an orthogonal frequency division multiplexing access (OFDMA) system. In the method, a) the transmission signal to be digitally clipped is divided into real and imaginary parts, b) magnitudes of the real and imaginary part signals are divided into a plurality clipping levels, and c) the transmission signal is respectively clipped by comparing the real and imaginary part signals with the plurality of clipping levels while allowing phase errors. In c), a plurality of comparators is used to respectively compare the real and imaginary parts of the complex number transmission signal with the plurality of clipping levels.

Abstract: A method for communication includes defining N respective symbol constellations in a signal space for N transmitters (24), N(2, subject to a predetermined power constraint, so as to produce a joint constellation including superpositions of symbols selected from the N symbol constellations. Data is transferred from the N transmitters by simultaneously transmitting from M the N transmitters N respective symbols selected respectively from the N symbol constellations. A composite symbol including a superposition of the N transmitted symbols is received. The received composite symbol is demodulated using the joint constellation so as to reconstruct the data transferred from the N transmitters.

Abstract: A method for decoding at least one signal, including: receiving the at least one signal, the at least one signal being transmitted by at least one transmitting antenna and received by at least one receiving antenna; defining a sphere having a predetermined radius and being centered on a particular symbol chosen among predetermined symbols forming a lattice constellation of symbols which may be received by the receiving antenna; and producing estimated symbols representative of at least one transmitted symbol carried by the at least one signal and identified among the predetermined symbols included in the sphere and likelihood values associated to the estimated symbols.

Abstract: A mobile station is capable of detecting a signal in the wireless communication systems using the Multiple Input Multiple Output (MIMO). The mobile station includes an apparatus that determines a vector of signals received by several receiving antennas. The apparatus estimates a channel between transmitting antenna and receiving antenna; forms a channel matrix; establishes, based on the channel state data, an order for detecting symbols transmitted by different transmitting antennas; calculates weight coefficients for detecting the symbols in the MIMO system; detects the symbols serially in the established order on the basis of the received signal vector; calculates the Euclidean distance between the detected symbols and the symbol constellation points; determines values of the Logarithmic Likelihood Ratio (LLR) for estimating the soft output bit probability, and forms a group of the most probable candidate symbols from the points of the symbol constellation.

Abstract: A tone selection module selects tones suitable for use in an orthogonal frequency division multiplexing (OFDM) data transmission device based on several constraints. These constraints include number of available tones, modulation type, and code rate. The OFDM device may use either wired or wireless transmission.

Abstract: A method and apparatus for choosing a modulation and coding rate in a MU-MIMO communication system is provided herein. During operation, a node will determine the MCR to feed back to the base even though the mobile does not know which of the possible interferers (if any) will be using the same time/frequency resources as the mobile. This takes place via the mobile node calculating best antenna weights (codebook choice) for each group of subcarriers that can be potentially used by the mobile. Transmit weights v for each interferer are then determined and the weights are utilized to determine a best modulation and coding rate for the mobile.

Abstract: An arrangement of interleavers allocates bits from an input symbol across sub-symbols transmitted via sub-carriers of multiple orthogonal frequency division multiplex (OFDM) carriers. The input bits are allocated in a fashion to provide separation across subcarriers, and rotation of sub-symbols across the OFDM carriers provides additional robustness in the present of signal path impairments.

Abstract: A combination equalizer and automatic gain control (AGC) is provided for high-speed receivers. The combination circuit comprises a first AGC having an input to accept a communication signal and an input to accept a first control signal. The first AGC modifies the communication signal gain in response to the first control signal, to supply a first stage signal at an output. An equalizer has an input to accept the first stage signal and an input to accept a second control signal. The equalizer modifies the frequency characteristics of the first stage signal in response to the second control signal, to supply an equalized signal at an output. A second AGC has an input to accept the equalized signal and an input to accept a third control signal. The second AGC modifies the equalized signal gain in response to the third control signal, to supply a second stage signal at an output.

Abstract: A system and method including deriving a subcarrier frequency from a binary data stream having a clock frequency, wherein the subcarrier frequency is substantially the same as the clock frequency; gating the subcarrier frequency using the data stream to produce a modulated OOK signal; determining a OOK subcarrier center frequency based on the modulated OOK signal with the clock frequency; delaying the modulated OOK signal relative to the binary data stream by a predetermined amount to produce a delayed modulated OOK signal; conditioning the modulated OOK signal and the delayed modulated OOK signal to create a differential transition signal in an I channel and a Q channel to provide a stable amplitude signal level reference at an input to an I and Q vector modulator.

Abstract: The present invention relates to a method for processing digital signals and to a transmission/reception system implementing said method; the present invention is based on the use of LDPC codes, in particular the LDPC code of the DVB-S2 standard, in combination with a QAM modulation, in particular the 1024QAM and 4096QAM modulations; in transmission, a bit permutation (Demux) is carried out prior to the QAM constellation mapping function; in reception, the bit permutation is carried out after the QAM constellation demapping function.

Abstract: A trellis processing technique for estimating a transmitted signal from a received signal acquired through a channel achieves a reduced computational structure when implementing a DDFSE-like branch metrics calculation by pre-storing computed values, which can be re-used. The technique involves storing differences between a received symbol and different products, each of which is a product of a channel coefficient corresponding to a least time delay and a different possible transmitted symbol. A summation of products is calculated, each product being a product of a possible transmitted signal symbol and a channel coefficient other than the channel coefficient corresponding to the least time delay, the summation being specific to a branch-start state in a trellis. The summation is combined with different stored differences in a calculation of branch metrics leading to different branch-end states in the trellis.

Abstract: Provided is a base station device capable of suppressing power consumption of a radio communication device and transmitting a pilot signal for measuring an uplink channel quality in a high frequency use efficiency. The base station device (2) includes: a resource block size decision unit (54) which decides the number of subcarriers to be allocated for the radio communication device (1); and a cyclic shift delay amount decision unit (55) which sets a cyclic shift delay amount used when performing cyclic shift delay diversity transmission according to the number of subcarriers decided by the resource block size decision unit (54). By using the cyclic shift delay amount set by the cyclic shift delay amount decision unit (55), the radio communication device (1) cyclic shift delay diversity transmission of the channel quality measuring signal.

Abstract: In a communications device a grouping unit uses channel state information when mapping data bits to a plurality of different constellation groups. Each constellation group is assigned to another modulation scheme. A plurality of sub-carriers is assigned to none or one of the constellation groups and each modulation uses another one of the constellation groups. The communications device includes at least one scalable interleaver unit, wherein each interleaver unit is assigned to one of the constellation groups and interleaves the assignment of data bits mapped to each constellation group and the sub-carriers that carry a symbol information derived from the data bits. As an example, the interleaver unit performs frequency interleaving by interleaving, at constellation level, the sub-carriers that carry the symbol information.

Abstract: A receiver of a multiple-input multiple-output (MIMO) system performs QR decomposition of the channel matrix to enable detection of a transmitted vector in a layered manner. In each layer, a sub-vector of the transmitted vector is estimated. A reactive tabu search is performed if an estimated symbol differs from a nearest symbol in the alphabet by a predetermined value. The receiver may order the entries of the channel matrix prior to QR decomposition to enable estimation in an optimum order. In another embodiment, a receiver performs multiple reactive tabu searches to estimate a transmitted vector. The receiver employs a fixed threshold or a variable threshold for a cost function used in the multiple reactive tabu searches depending on whether the MIMO system is under-determined or not. The techniques enable low bit-error rate (BER) performance in MIMO systems with large number of antennas and when higher-order modulation techniques are used.

Abstract: The present disclosure relates generally to a system and method for superposition coding and interference cancellation in a multiple input multiple output (MIMO) system. In one example, the method includes demultiplexing a signal of a user into at least first and second signal portions and demultiplexing a signal of another user into at least third and fourth signal portions. Superposition coding is performed on the first and third signal portions to form a first composite signal and performed on the second and fourth signal portions to form a second composite signal. The first composite signal is transmitted via at least one antenna of a MIMO system and the second composite signal is transmitted via at least another antenna of the MIMO system.

Abstract: Systems and methods for determining an unknown QPSK or QAM constellation from a set of possible received constellations are described. One method utilizes a histogram of the power of the signal after inter-symbol-interference has been minimized with a modified constant modulus algorithm equalizer. The constellation may be determined before carrier frequency and phase has been fully recovered. An unknown QPSK or QAM constellation may be identified before or after equalization using disclosed methods for analyzing an output power histogram.

Abstract: A subscriber station for use in a wireless network capable of communicating according to a multi-carrier protocol, such as OFDM or OFDMA. The subscriber station comprises a size M Fourier Transform (FFT or DFT) block for receiving input symbols and generating M FT pre-coded outputs and a size N inverse Fourier Transform (IFFT or IDFT) block capable of receiving N inputs, where the N inputs include the M FT pre-coded outputs from the size M FT block. The size N IFT block generates N outputs to be transmitted to a base station of the wireless network. The input symbols comprise user data traffic to be transmitted to the base station. The size N IFT block also receives signaling and control information on at least some of N-M inputs. The FT pre-coding generates a time-domain signal that has a relatively lower peak-to-average power ratio (PAPR).