Abstract: A method for transmitting messages from first units of an integrated circuit to at least one second unit of the integrated circuit. The first units generate first digital messages and transform them into second digital messages obtained by application of an orthogonal or quasi-orthogonal transformation to the first messages. The second messages of the first units are added up and transmitted to the second unit.

Abstract: The present invention relates to an orthogonal frequency division multiplexing (OFDM) signal transmitting and receiving device, in which a peak to average power ratio characteristic is improved without reducing a data transmission speed. The OFDM signal transmitting device separates a digital modulated symbol as a real part and an imaginary part, and performs discrete cosine transform (DCT) and discrete sine transform (DST) operations respectively for real and imaginary part symbols, performs an inverse fast Fourier transform operation, and generates an OFDM symbol. The OFDM signal receiving device performs a fast Fourier transform operation for the OFDM symbol, and performs an inverse DCT operation and an inverse DST operation, performs a digital demodulating operation, and generates a final binary data symbol.

Abstract: Transmission is scheduled in a multi-cell multi-carrier wireless network. Assignments are determined for subcarriers by determining marginal gains for receivers, determining a receiver and an associated base station corresponding to a highest marginal gain, and assigning the receiver to the base station. These steps may be iteratively repeated until each of the receivers is assigned to a base station. The subcarriers are then allocated to the receivers by selecting the receiver with the highest gain. Alternatively, assignments are determined for subcarriers by determining a maximum additional queue size reduction, determining an assignment for each of the subcarriers, determining a receiver associated with a base station that has the determined maximum additional queue size reduction, assigning the receiver to the base station, and allocating the subcarriers to the receivers in the base stations.

Abstract: Systems and methods according to the present invention provide channel estimation methods, systems and devices which determine a coarse channel estimate (40) and a fine channel estimate (66). The coarse channel (40) estimate can be determined based on the channel estimation sequence transmitted to the receiver and then used to detect header symbols. The header symbols can be used to calculate additional channel estimates which can then be combined with the coarse channel estimate (40) to determine a fine channel estimate (66).

Abstract: In this invention, we propose a near maximum likelihood (ML) method for the decoding of multiple input multiple output systems. By employing the metric-first search method, Schnorr-Euchner enumeration, and branch length thresholds in a single frame systematically, the proposed technique provides a higher efficiency than other conventional near ML decoding schemes. From simulation results, it is confirmed that the proposed method has lower computational complexity than other near ML decoders while maintaining the bit error rate (BER) very close to the ML performance. The proposed method in addition possesses the capability of allowing flexible tradeoffs between the computational complexity and BER performance.

Abstract: A Generalized Rake (G-Rake) receiver is adapted for Golden code reception in a CDMA system. Signals transmitted by two or more transmit antennas are received at two or more receiver antennas. The signal from each receiver antenna is despread, and channel estimation is performed for each transmit antenna. G-Rake combining weights are calculated based on impairment correlation across G-Rake fingers and channel coefficients corresponding to each transmit antenna. The despread values from each symbol period are combined over a plurality of symbol periods based on the combining weights. The combined values are processed using coefficients derived from the Golden number to generate a set of decision variables, and the Golden encoded symbols are jointly detected from the decision variables. In some embodiments, spherical decoding and triangularization significantly simplify the decoding problem formulation.

Abstract: A decoder apparatus for decoding a first input set of demodulated data elements obtained by demodulating transmitted data elements received over a transmission channel so as to obtain a corresponding output set of decoded data elements. The decoder apparatus includes a first register a first selector coupled to the first register, a second selector coupled to the second register, and a combiner coupled to the first and the second selection circuits and operable to combine selected demodulated data elements with selected channel description elements. The decoder apparatus still further includes a controller coupled to the first and second selectors and to the combiner, that is adapted to generate a plurality of signals defining a control sequence for driving the first and second selectors and the combiner. Said controller is adapted to be configured so as to generate at least two control sequences according to the selected transmission diversity scheme.

Abstract: A subscriber station is provided for use in a wireless network communicating according to a multi-carrier protocol, such as OFDM or OFDMA. The subscriber station comprises: a size M1 Fourier Transform (FT) block that receives input symbols and generates M1 FT pre-coded outputs; a size M2 Fourier Transform (FT) block that receives input symbols and generates M2 FT pre-coded outputs; and a size N inverse Fourier Transform (IFT) block that receives N inputs, including the M1 FT pre-coded outputs and the M2 FT pre-coded outputs, and generates N outputs to be transmitted to a base station. The FT blocks are Fast Fourier Transform blocks or Discrete Fourier Transform blocks. The IFT block is an inverse Fast Fourier Transform block or an inverse Discrete Fourier Transform block.

Abstract: A communication controller and a method is provided for synchronizing a wireless communication device and a wireless communication network having two or more transmit antennas, which support transmit diversity. A reference signal is received from the wireless communication network via each one of a pair of the two or more transmit antennas. A preferred phase offset is then determined for the pair of transmit antennas, and then transmitted to the wireless communication network. Further adjustments of the requested phase and amplitude of the communications transmitted using the pair of transmit antennas are suspended, until further transmissions are received from the wireless communication network via the corresponding transmit antennas, which can be decoded in accordance with the preferred phase offset or a timer has elapsed corresponding to the maximum time needed for the wireless communication network to receive the preferred phase offset and synchronize to the same.

Abstract: Provided is an orthogonal frequency division multiplexing (OFDM) apparatus using a 3-dimensional (3D) signal constellation. The apparatus performs 2D inverse fast Fourier transform on a set of 3D subchannel signals that is mapped by a signal constellation including signal points distributed on the surface of a 3D sphere.

Abstract: A receiving apparatus includes a first transform unit configured to perform orthogonal transform on a time-domain input signal and perform saturation when an overflow occurs to transform the input signal into a plurality of frequency-domain signals, a second transform unit configured to perform orthogonal transform on the time-domain input signal while restricting the number of bits during orthogonal transform and continue operations while not performing saturation when at least one of the operations overflows and leaving the operation overflowing to transform the input signal into a plurality of frequency-domain signals, and a bit restricting control unit configured to control the number of bits during orthogonal transform by the second transform unit based on output signals of the first transform unit.

Abstract: A received signal having pilots is converted to a first signal in the frequency domain having the pilots. The pilots are extracted from the first signal to obtain extracted pilots to form a second signal. The second signal is used to provide a first estimate of a channel. The first estimate is converted to the time domain. Noise is removed from the first estimate in the time domain to provide a second estimate of the channel in the time domain. An autocorrelation of the channel in the frequency domain is determined using the second estimate of the channel. Extension signals are determined using the autocorrelation. The extension signals are appended to the first estimate of the channel to obtain a third estimate of the channel. The third estimate is used to provide a data signal in the frequency domain.

Abstract: Methods and apparatus for an adaptable frame structure are disclosed, where a transmission frame consists of multiple subframes, each containing a downlink transmission period and an uplink transmission period. A downlink broadcasting signal is used to indicate the configuration of each subframe. The downlink and uplink period configuration in each subframe can be independently adapted to support applications with a variety of traffic patterns, from symmetric to highly asymmetric. A great variety of applications from normal two-way data communications to voice communications and video or data broadcasting can be supported efficiently in a single frequency band, while multiple frequency bands can be used to increase capacity or add more flexibility.

Abstract: Systems and techniques relating to wireless communications are described. A described technique includes receiving a plurality of symbols, observing a plurality of data samples in adjacent symbols, and calculating an estimate of an integer portion of a carrier frequency offset based on a cyclic shift and a phase shift of the data samples between symbols. Calculating the estimate can include calculating sum values corresponding to respective symbol indices. Each of the sum values can be based on a summation of max values that correspond to respective data subcarrier indices, the max values being based on a maximum of an absolute value of a real component of a base value and an absolute value of an imaginary component of the base value, where the base value is based on at least one of the data samples.

Abstract: A wireless receiver that sorts packets including a packet detector, multiple correlators, and multiple packet processors. Each correlator correlates a received signal according to packet type. Each packet processor processes the received signal according to packet type. A signal power detector may be provided to initially qualify the received signal as containing a packet, and the correlators determine whether a packet is present. The correlators may be configured for sequential or simultaneous correlation. For the simultaneous correlator configuration, a correlation monitor is provided to monitor correlation results to determine if the received signal contains a packet, and if so, to determine packet type. A low SNR packet detector may be provided which correlates the received signal to detect weak packet signals.

Abstract: Techniques for sending multiple-input multiple-output (MIMO) transmissions in wireless communication systems are described. In one design, a transmitter sends a first reference signal via a first link, e.g., a cell-specific reference signal via the downlink. The transmitter receives channel quality indicator (CQI) information determined by a receiver based on the first reference signal. The transmitter also receives a second reference signal from the receiver via a second link, e.g., a sounding reference signal via the uplink. The transmitter obtains at least one MIMO channel matrix for the first link based on the second reference signal. The transmitter determines at least one precoding matrix based on the at least one MIMO channel matrix, e.g., in accordance with ideal eigen-beamforming or pseudo eigen-beamforming. The transmitter then sends a data transmission to the receiver based on the at least one precoding matrix and the CQI information.

Abstract: Various embodiments are described which may serve to improve spreading channel code selection in wireless technologies that employ two-stage ranging. For example, some of the embodiments enable a number of spreading codes to be reused at each network node (111, 112), potentially increasing the number of codes available to each remote unit and thereby reducing the collision rate. Rather than simply selecting a spreading channel code randomly, remote units (101-103), in some embodiments, select a spreading channel code based on one or more considerations such as pilot signal strength, remote unit location, a remote unit mobility level, and a priority class associated with the remote unit. Depending on the embodiment, network nodes can partition the spreading codes into groups and then assign link bandwidth to remote units based on the group associated with the code selected by that remote unit.

Abstract: A method of processing a signal in a wireless digital communications system, wherein a source of disturbance affects differently at least first and second portions of a received signal carrying user data and/or control data, the method comprising: identifying the second portion of the received signal, most affected by the source of disturbance; generating a first estimate of the disturbance (PI) for received samples in the first, less affected portion of the received signal; generating a second estimate of the disturbance (PI(SCH)) for received samples in the second portion of the received signal; and using the first and second disturbance estimates to generate reliability information for the data bits corresponding to the received signal samples, for use in a decoding process to estimate the transmitted data bits.

Abstract: An apparatus includes an estimator that includes a receiver that receives a plurality of frequency-domain symbols. Each symbol includes at least one of a plurality of pilot samples and a plurality of data samples. The estimator also includes a framer that observes the at least one of the plurality of pilot samples and the plurality of data samples in adjacent symbols, and a calculator that calculates an integer carrier frequency offset (CFO) estimate based on a reliability metric based on the at least one of the plurality of pilot samples and the plurality of data samples that are included in the frequency-domain symbols.

Abstract: Provided is a carrier allocation method in a multi cell OFDMA system capable of improving the system capacity and the bit error rate performance. In the method, a user terminal U which has received broadcast information (S101) uses an empty carrier to transmit a known symbol to a base station device (S103). The base station device estimates an average channel gain of an empty carrier block by using the received known symbol (S104), compares the channel gain sizes of the respective carrier blocks according to the estimated average channel gain and allocates a carrier block having a large channel gain to the user terminal (S105), and compares channel gains of the respective carriers in the carrier block allocated to the user terminal and selects a carrier having a channel gain lower than a predetermined threshold value (S106).

Abstract: An embodiment of the invention provides a wireless communication system for carrying out a spatial multiplexing communication between a transmitter, and a receiver, the system including: a channel information matrix acquiring section for acquiring a channel information matrix; a weighting factor matrix arithmetically operating section for obtaining a weighting factor matrix based on the channel information matrix thus acquired; a normalizing section for executing processing for normalizing the weighting factor matrix; a detecting section for detecting whether there is presence or absence of an abnormality in the processing; a weighting processing section for executing weighting processing based on the weighting factor matrix for each of transmission signals transmitted from the transmitter in accordance with a detection result obtained from the detecting section; and a transmitting section for transmitting the transmission signals for which the weighting processing section executes the weighting processing fr

Abstract: A system includes an estimation module, a processing module, and a control module. The estimation module receives a signal having N sub-carriers and generates N first estimates for channel gains of the N sub-carriers, where N is an integer greater than 1. The processing module generates N second estimates based on the N first estimates. The control module generates N differences between each of the N first estimates and corresponding ones of the N second estimates and estimates (i) a channel gain of the signal and (ii) a preamble sequence in the signal based on the N differences.

Abstract: The present invention relates to a wireless communication system. More particularly, the present invention relates to a method for enabling a transmitter to transmit a sequence in a wireless communication system, and to an apparatus for the same. A sequence-transmitting method comprises the steps of: performing at least one of a complex conjugate operation and a reverse operation on a first sequence to generate a second sequence; mapping the second sequence to a plurality of subcarriers in an Orthogonal Frequency Division Multiple Access (OFDMA) symbol; and transmitting the OFDMA symbol to a receiver. The invention also relates to an apparatus for the sequence-generating method.

Abstract: A passive optical network (PON) device, system and method include an optical line terminal (OLT) receiver configured to receive multiple signals at different wavelengths simultaneously and enable multiple transmitters to operate at the same time during one upstream time slot. The optical line terminal employs Orthogonal Frequency Division Multiple Access (OFDMA) to transparently support a plurality of applications and enable dynamic bandwidth allocation among these applications where the bandwidth is allocated in two dimensional frequency and time space.

Abstract: A phase-shift based pre-coding scheme used in a transmitting side and a receiving side that has less complexity than those of a space-time coding scheme, that can support various spatial multiplexing rates while maintaining the advantages of the phase-shift diversity scheme, that has less channel sensitivity than that of the pre-coding scheme, and that only requires a low capacity codebook is provided.

Abstract: Of any one of transmission method X of transmitting modulated signal A and modulated signal B including the same data from a plurality of antennas and transmission method Y of transmitting modulated signal A and modulated signal B having different data from the plurality of antennas, base station apparatus 201 does not change the transmission method during data transmission and changes only the modulation scheme. Base station apparatus 201 transmits modulated signal A and modulated signal B to communication terminal apparatus 251 using the determined transmission method and modulation scheme. In this way, it is possible to improve data transmission efficiency when transmitting data using the plurality of antennas.

Abstract: Methods and systems for processing multiple preambles for a wireless signal are disclosed herein. Aspects of the method may comprise selecting a portion of a preamble, and shifting the selected portion of the preamble to generate a plurality of subsequent preambles. The preamble may comprise a legacy preamble and/or an 802.11(n) preamble. The selected portion of the preamble may comprise a short training sequence. The shifting may comprise circular shifting. The circular shifting may comprise forward circular shifting and/or backwards circular shifting. The generated plurality of subsequent preambles may be transmitted via a plurality of antennas. A phase roll may be added to the selected portion of the preamble to generate the plurality of subsequent preambles.

Abstract: To provide a digital data transmitting apparatus and a digital data receiving apparatus that can realize, even when a transmission channel characteristic changes because of aged deterioration or the like of a relay, improvement of a reception performance following the change. A transmitting apparatus 1 generates a multiplexing frame formed by N slots including control information, data, outer parities, stuff bits, and inner parities and added with synchronization, pilot, and a transmission control signal and a parity and transmits data of the respective slots in a transmission system designated by the transmission control signal. In this case, pilot signals are symbols allocated to all signal points in order determined in advance for each of modulation schemes. A receiving apparatus 2 rewrites a phase error table 214 to calculate a phase error and performs synchronous detection according to the pilot signals. The receiving apparatus 2 also rewrites a likelihood table 235 to perform inner code decoding.

Abstract: A method and apparatus for fast cell search based on a chirp reference signal transmission is disclosed herein. A primary synchronization channel (P-SCH) and two secondary synchronization channels (S-SCH1 and S-SCH2) will be utilized. S-SCH1 will comprise a reference sequence having a first index value and S-SCH2 will comprise a reference sequence having a second index value. S-SCH1 and S-SCH2 will be scrambled with a first and a second scrambling code, respectively. The second scrambling code will be based on the first index value.

Abstract: A quantized multi-rank beamforming scheme for multiple-antenna systems such as a multiple-input-multiple-output (MIMO) wireless downlink. User equipment (UE) estimates downlink channel and transmit power and determines rank and power allocations. A quantized beamforming matrix is then determined by the UE using successive beamforming. The UE also determines channel quality indices (CQI) which it feeds-back to the wireless downlink base station along with the index of the quantized beamforming matrix. The base station uses the CQI information to select a UE for scheduling of downlink transmission and the quantized beamforming matrix index received from the selected UE to beamform the downlink transmission to the UE. Base station overhead and is minimized while providing near-optimal performance given the constraints of a limited feed-back channel and computational complexity of the UE.

Abstract: The present invention relates to a system for canceling co-channel interference (CC) in a cellular orthogonal frequency division multiplexing (OFDM) system. The system canceling co-channel interference (CCI) in a cellular orthogonal frequency division multiplexing (OFDM) system comprises a mobile station (MS) receiver including a feedback generation unit for generating a feedback to a base station (BS) so as to control a transmission power of the transmitting frame of the BS, and a maximum likelihood estimation (MLE) CCI cancellation unit for canceling CCI signals arriving from neighbor cells; and a BS transmitter including a closed-loop power control unit for controlling the transmission power of the transmitting frame according to the feedback received from the MS such that received power of desired signal at the MS receiver is different from that of an interferer signal.

Abstract: An embodiment of the present invention includes a transceiver for use in a multi-input-multi-output (MIMO) Orthogonal Frequency Domain Multiplexing (OFDM) wireless communication system. The transceiver decodes and remodulates certain signal fields and uses the same to update the coefficients of a frequency equalizer thereby improving channel estimation and extending training.

Abstract: A plurality of data signals are separated into parallel bit streams with each parallel stream having a bandwidth characteristic such that the combined cumulative effect of all the individual bandwidths produces a spectral characteristic of the data signals that match the spectral high speed data characteristic of a twisted pair.

Abstract: A method of allocating sub-channel signal interleaving patterns to BSs forming a wireless communication system that divides a frequency band into a plurality of sub-carriers and including a plurality of sub-channels, which are a set of predetermined adjacent sub-carriers. The method includes: creating a basic orthogonal sequence having a length identical to a number of the sub-carriers forming the sub-channel; creating a plurality of sequences having a same length as the basic orthogonal sequence by cyclic-shifting the basic orthogonal sequence a predetermined number of times or performing a modulo operation based on a number of the sub-carriers forming the sub-channel, after adding a predetermined offset to the cyclic-shifted basic orthogonal sequence; selecting a predetermined number of sequences corresponding to a number of the BSs from among the plurality of sequences; and allocating the selected sequences as the sub-channel signal interleaving patterns for the BSs.

Abstract: It is an object to provide a wireless communication base station device that can prevent the decline of a system throughput due to the degradation of a utilization efficiency of a communication resource of a channel for carrying out a frequency diversity transmission when a frequency scheduling transmission and a frequency diversity transmission are concurrently carried out in multiple carrier communication. In the wireless communication base station device, a modulation unit (12) carries out modulation processing for Dch data after coding to generate a Dch data symbol. A modulation unit (22) carries out modulation processing for Lch data after coding to generate an Lch data symbol. An allocation unit (103) allocates the Dch data symbol and Lch data symbol to each sub-carrier composing an OFDM symbol and outputs the allocated sub-carrier to a multiplex unit (104).

Abstract: An apparatus for generating sets of radio parameters includes a first deriving unit deriving a set of radio parameters for specifying a symbol including an effective symbol part with the same period as the effective symbol part specified by another set of radio parameters and a guard interval part with a different period from the guard interval part specified by the other set of radio parameters. The apparatus further includes a second deriving unit deriving a set of radio parameters so that an occupancy proportion of the guard interval part in a single symbol specified by another set of radio parameters is equal to an occupancy proportion of the guard interval part in a single symbol specified by the other set of radio parameters.

Abstract: An OFDM reception device detects a time at which impulse noise occurs in a received OFDM signal, and specifies a start position candidate period that does not have intersymbol interference and is estimated to have a guard interval signal in a symbol. When setting a FFT window of an effective symbol length in a symbol duration of each symbol, if the impulse noise occurrence time is included in the symbol, the OFDM reception device determines a start position of the FFT window within a range of the start position candidate period so as to exclude the impulse noise occurrence time as much as possible.

Abstract: Multi-carrier transmission is performed without inserting a repetitive signal into guard interval periods. A transmitter provides guard interval periods by using a null signal to save transmission power and prevent the deterioration of the SN ratio. Delayed waves at the head of each received symbol cause high-frequency waves to occur and carriers to interfere with one another. Accordingly, a receiver adds a component following each received symbol to a delayed-wave component at the head of the received symbol. As a result, the delayed-wave component at the head of the received symbol and the added component become continuous in wave form and subcarriers do not interfere with each other.

Abstract: An inter-carrier interface removal device can improve estimation accuracy of inter-carrier interference caused by Doppler shift in a received multi-carrier signal moving at a high speed, and a reception characteristic of the multi-carrier signal after removing the inter-carrier interference.

Abstract: A receiver that employs inherent characteristics of frequency domain representation of the data symbols. By computing a differential-in-frequency function across a large number of OFDM tones, robust estimates of time and frequency offset are obtained. The obtained time and frequency estimates provide control to sampling and frequency offset elements that are interposed between the reliever input and subsequent receiver stages.

Abstract: A method for feeding back a Channel Quality Indicator (CQI) in a mobile communication system is provided. The method includes determining a number of subchannels for which the MS feeds back CQIs based on a preset feedback efficiency factor, selecting the determined number of subchannels in a descending order of channel quality, and feeding back the CQIs of the selected subchannels to a Base Station (BS).

Abstract: A transmitting device is provided that generates OFDM symbols by identifying a sampling frequency of input data that is input from an external device, determining a number of inverse Fourier transform sample points and a number of sampling points of a redundant data portion in accordance with the identified sampling frequency, and subjecting the input data to OFDM modulation using the determined number of sampling points. The transmitting device then transmits the generated OFDM symbols.

Abstract: This invention provides a code division multiplexing method and system which include the following steps: constructing the basic grouping perfect orthogonal complementary code pair mate, modulating the C code and S code of the basic grouping perfect orthogonal complementary code pair mate to the M orthogonal carrier frequency or orthogonal polarization waves which are serially in time, and implementing continuous shift on the modulated basic grouping perfect orthogonal complementary code pair mate.

Abstract: A method for transmitting a digital signal is described, wherein the digital signal is to be transmitted by a plurality of antennas and a 2-domain pre-transformation is carried out, i.e., in course of a pre-transformation modulation symbols assigned to subcarriers having different frequencies and assigned to subcarriers sent by different antennas are linearly combined.

Abstract: Delay estimation apparatus and method, comprising: a correlation step which a correlation function between a received signal and a supplied template waveform is generated, AD conversion step at which said correlation output generated at said correlation step is uniformly sampled into discrete samples; and arithmetic operation step at which a time delay estimate of the received signal based on said discrete samples generated at said AD conversion step is computed, wherein a selection criterion depending on the digital sampling frequency used at said AD conversion means is checked, if said selection criterion is satisfied, computes the time delay estimate based on the direct pick method, and if said selection criterion does not hold, computes the time delay estimate based on the simplified maximum likelihood (ML) method.

Abstract: Pilot sequences (for aiding a receiver in estimating a channel) are disposed in a frame structure that has subframes of sub-carriers and symbol positions. Locations of common pilot sequences are predetermined, and includes 1) in each subframe, a pilot sequence is disposed in a first symbol position for each of at least two staggered sub-carriers, and 2) in at least one subframe, at least one pilot sequence is disposed in other than the first symbol position and in a sub-carrier other than any of the at least two staggered sub-carriers. Dedicated pilot sequences, whose locations in the frame are not predetermined, are disposed in response to an indication of channel quality received over a wireless link. Common pilot sequences may relate to one or two transmit antennas, and dedicated pilot sequences may enable addition of third and fourth transmit antennas.

Abstract: A radiofrequency signal is converted to an intermediate frequency signal by a tuner, which is amplified by a variable gain amplifier. The so-amplified signal is converted into a digital signal by an ADC, which is supplied to an FFT, where it is separated into signals set every carrier, followed by being supplied to equalizers different in characteristic. The digital signal outputted from the ADC is further supplied to a level converting circuit from which a control signal is generated. The control signal is supplied to a DAC and a Doppler frequency detector. The DAC generates a gain control signal and supplies the same to the variable gain amplifier. The Doppler frequency detector outputs a frequency component of the control signal as a Doppler detection signal. The Doppler detection signal is compared with a threshold value by a comparator. A selector selects one of signals outputted from the equalizers, in accordance with a select signal indicative of the result of comparison.

Abstract: The high quality PCS communications are enabled in environments where adjacent PCS service bands operate with out-of-band harmonics that would otherwise interfere with the system's operation. The highly bandwidth-efficient communications method combines a form of time division duplex (TDD), frequency division duplex (FDD), time division multiple access (TDMA), orthogonal frequency division multiplexing (OFDM), spatial diversity, and polarization diversity in various unique combinations. The method provides excellent fade resistance. The method enables changing a user's available bandwidth on demand by assigning additional TDMA slots during the user's session.

Abstract: Orthogonal frequency division multiplexing (OFDM) has been specified by IEEE 802.11a standard as the transmission technique for high-rate wireless local area networks (WLANs). Performance of an OFDM system, however, is heavily degraded by random Wiener phase noise, which causes both common phase error (CPE) and inter-carrier interference (ICI). A method and algorithm is disclosed for efficiently eliminating the effect of phase noise in OFDM based WLANs.

Abstract: A frequency offset detector is provided which is adaptable to a great frequency offset of one or more carrier waves in an OFDM signal. The frequency offset detector comprises a multiplication circuit which multiplies, by a pseudorandom number bit sequence, a reception signal generated by Fourier transformation of an OFDM modulated signal wherein pilot symbols are dispersed and arranged in accordance with four kinds of patterns and periodically transmitted. Four arithmetic circuits extract the pilot symbols corresponding to the respective patterns from a result of the multiplication by the multiplication circuit for each of the four kinds of patterns and calculate the sum of phase differences among the extracted pilot symbols to output an absolute value. A detection circuit detects a frequency offset on the basis of a maximum value of the absolute values calculated by the four arithmetic circuits.