Abstract: An apparatus and method for assigning sub-carriers in an orthogonal frequency division multiplex (OFDM) system are disclosed. In the apparatus and method, data is transmitted through at least one transmit antenna. At least two sub-carriers in a predetermined frequency band are assigned to a user equipment (UE), for data transmission. A Node B groups sub-carriers available to the OFDM system into sub-carrier groups, each having at least two sub-carriers, transmits data to the UE on sub-carriers in the sub-carrier groups, selects at least one sub-carrier group for the UE based on channel condition information about each of the sub-carrier groups received from the UE, and assigns the selected sub-carrier group to the UE.

Abstract: A first rate matching stage matches a number of input bits coming from a transport channel including a high-speed downlink shared channel (HS-DSCH) of a block of data bits to be transmitted from a base station of a communications network to one or more pieces of user equipment (UE) to a selected number of intermediate bits as determined by the buffer size management system. A virtual buffer stores the selected number of intermediate bits. A second rate matching stage matches the selected number of intermediate bits to a number of output bits equal to a maximum number of bits that is guaranteed to be transmitted by a set of high-speed physical downlink shared channels (HS-PDSCH) associated with the transport channel in a given time interval without adding bits.

Abstract: Which permits to solve the problems relating to the interference produced among communications equipment of the same technology but belonging to different communications and which simultaneously use the same communications channel in time and frequency. It comprises modifying one of the parameters of the starting signal. The main advantage of the invention is that, in a simple way, it allows equipment to be correctly synchronised with the signals reaching it from its own network while ignoring signals of lesser power received from other networks using the same or different technology, without any need to carry out a complex and costly processing on reception.

Abstract: A method for processing signals received in a communications system determines symbol information corresponding to a re-transmitted packet, compared the symbol information of the re-transmitted packet with symbol information of an original packet, and formed a combined packet based on a result of the comparing step.

Abstract: A receiver of a multicarrier communication system capable of reducing inter-subcarrier interfering signals is to be provided. Receive signals received by a receiving antenna are amplified by a receiving amplifier, subjected to quadrature demodulation by multipliers with respect to the respective subcarriers, and band-limited by lowpass filters. The signals band-limited by the lowpass filters are converted into digital signals by A/D converters at a sampling frequency fs. With respect to the receive signals converted into digital signals, interfering signals leaking between subcarriers are estimated by using A/D converted by the A/D converters and are canceled. The receive signals reduced in interfering signals are multiplexed into a single sequence by a multiplexer, and decoded by a decoder into output signals.

Abstract: A device (D) is dedicated to managing transmission of digital data blocks in High-Speed Downlink Shared Channel (HS-DSCH) downlink transport channel set up between a base station of a communications network and a user equipment. It comprises processing means (MT) adapted, each time that a given block must be transmitted to the user equipment via the transport channel, to select successive values of the redundancy parameter XRV in accordance with a selected sequence in which the value of the redundancy parameter XRV used for the first block transmission is selected to give priority to transmitting systematic bits.

Abstract: A method for maintaining the quality of transmission from a head end to a service unit in a telecommunications system that uses a multi-carrier transmission scheme with dynamic bandwidth allocation is disclosed. The method involves allocating a first payload channel to a service unit in a subband of a transmission channel of the telecommunications system and monitoring the quality of the first payload channel. When the quality of the first payload channel drops below a threshold, the method allocates a second, different payload channel to the channel unit.

Abstract: A code division multiple access subscriber unit comprises an antenna configured to output a radio frequency signal, the radio frequency signal having a quadrature (Q) channel and an in-phase (I) channel. A circuit coupled to the antenna, the circuit being configured to generate power control bits which are carried by one of the I and Q channels and not the other one of the I and Q channels, the power control bits are spread coded and are adapted to control an output power of a base station. The radio frequency signal is a first radio frequency signal, the circuit is further configured to generate the power control bits based on a power level of a second radio frequency signal output by a base station and an interference level associated with the second radio frequency signal.

Abstract: Interleaving methods and apparatus are disclosed for an in-band on-channel digital audio broadcasting system. The guard periods that separate any two adjacent symbols in a conventional OFDM system can provide a mechanism for OFDM frame synchronization. The guard period of successive OFDM frames is utilized to establish one or more unique positive or negative patterns and thereby provide a mechanism for interleaver synchronization. By proper positioning of the guard period patterns, one or more particular portions of each interleaver block are identified, such as the beginning and midpoint of each interleaver block. The present invention identifies the beginning of each interleaver block, for example, by positioning the fourth negative cyclic prefix with OFDM frame zero (0). The present invention can optionally identify the midpoint of each interleaver block, for example, by positioning the fourth negative cyclic prefix with OFDM frame 206.

Abstract: A closed loop feedback system is employed in a receiver to automatically compensate the communication signal from twisted pair cables for AC and DC losses. This is accomplished through the use of a reference pulse signal which is sent along with other digital information. At the receiver, the reference pulse signal is restored to its proper level through a Pulse Width Modulation (PWM)-controlled variable compensation amplifier circuit. The received reference signal is compared to a known reference value and the duty cycle of the PWM circuit is adjusted until the proper level reference signal is achieved. Thereafter, the digital signal is extracted. OFDM (Orthogonal Frequency Division Multiplexing) with pilot tones are used to maximize payload while minimizing crosstalk effects. The pilot tones locate the OFDM symbols in time while supplying compensation information concerning the transmission medium.

Abstract: A technique for interference level estimation for a WCDMA system based on the low order statistics of Beaulieu Series is provided. Correlation of a locally generated copy of a dedicated physical control channel (DPCCH) with the input samples of the radio frequency message is performed using low order statistics of a Beaulieu Series to estimate an interference level and thereby implicitly separate a set of multipath components from a noise floor.

Abstract: An apparatus for OFDM communications includes an equalizer filter configured to receive input data and to apply a tap setting to the input data to generate output data. The input data includes a first real component and a first imaginary component. The tap setting includes a second real component and a second imaginary component. The output data includes a third real component and a third imaginary component, and the third real component is time-multiplexed with the third imaginary component. A method for OFDM communications includes applying a tap setting to input data to generate output data.

Abstract: A mobile terminal apparatus includes a channel compensation processor configured to carry out a channel compensation process on a first channel reception signal using a channel estimation value obtained for the first channel based on a plurality of known signals received from a base station; and a channel re-compensation processor to carry out a channel compensation process again on the first channel with a channel estimation value of the first channel obtained based on a plurality of known signals including at least a known signal which is received after reception of the first channel when a decoding result of the first channel reception signal after the channel compensation process by the processor is defined as an error. With this, error rate of the first channel is reduced and the number of retransmission according to HARQ is reduced, so that throughput in the mobile terminal can be improved.

Abstract: Various embodiments are described for adaptive puncturing techniques involving an adaptive bit loading block to select a modulation scheme and a puncturing pattern for each of a plurality of subcarriers or subcarrier bands based on subcarrier channel state information.

Abstract: The OFDM communications system for wireless networks includes at least one transmitter and at least one receiver. Each transmitter includes a signal source, a transmit modulator that arranges the data into packets and appends a pilot symbol of a repeated pseudo random binary sequence to the start of each packet, a multiplexer, an inverse fast Fourier transform, an up-sampler, a digital low pass filter, a digital to analogue converter, and an RF module. Each receiver includes an RF module, an analogue to digital converter, a digital low pass filter, a down-sampler, a frame detector to search for significant pilot symbol correlations and make initial estimates of at least one signal parameter, a digital phase locked loop to remove estimated frequency- and phase-offsets, a fast Fourier transform operator, a linear phase corrector to remove estimated sub-sample timing errors, a decision block, and a demultiplexer.

Abstract: An apparatus for reducing the crest factor of a multi-carrier transmission system. The apparatus comprises a plurality of single carrier crest factor reduction circuits. Each of the single carrier crest factor reduction circuits receives a selected one of a plurality of single carrier signals and generates a crest factor reduced (CFR) single carrier signal. The apparatus also comprises an up-converter for up-converting each of the CFR single carrier signals to a selected frequency and combining the up-converted CFR single carrier signals to thereby produce a multi-carrier signal. The apparatus further comprises a first multi-carrier crest factor reduction circuit for receiving the multi-carrier signal and generating a first crest factor reduced (CFR) multi-carrier signal.

Abstract: The present invention divides the available sub-carriers in an OFDM symbol window into N groups of sub-carriers wherein each group will be associated with sub-bands. In one embodiment, the sub-carriers in a group are spread throughout the range of sub-carriers to improve frequency diversity, and the sub-carriers assigned to any one group are separated by a constant offset. The sub-carriers in the group may be offset by an integer power of two. Within each group, sub-bands are defined using frequency hopping patterns among sub-carriers in the group from one OFDM symbol window to another. A pseudo-random pattern may be employed for sub-carrier mapping from one OFDM symbol window to the next to effectively distribute the sub-bands across the selected band of sub-carriers for the group.

Abstract: This permits the transmission of signals over the electricity network in such a way that the spectral density of power is adjusted to the regulations in the current rules by means of the possibility of introducing notches in transmission in an efficient manner. It is characterised by the adjustment of the power in one or more carriers of an OFDM signal for generating these notches, through the use of IDFTs of at least 1024 points (if the IDFT is complex) or at least 2048 points (if the IDFT is real) and through the use of a window to multiply the symbols to be transmitted in time.

Abstract: Systems for multipoint-to-point communication using orthogonal frequency division multiplexing and identification codes are provided. In one embodiment, a system comprises: a host unit; and a plurality of remote units using a multiple access scheme to communicate at the same time with the host unit using orthogonal frequency division multiplexing (OFDM); wherein the host unit allocates orthogonal tones within the system to the plurality of remote units; wherein the host unit sends an adjustment signal to at least one of the remote units instructing the at least one remote unit to adjust the timing of transmissions from the remote unit to improve orthogonality of an OFDM waveform received at the host unit, and wherein the host unit associates an address code with each of the plurality of remote units for designating downstream signals to the remote units.

Abstract: In a transmitting/receiving method, a transmitter device transmits a vertical polarization signal and a horizontal polarization signal, and a receiver device receives the vertical and horizontal polarization signals transmitted by the transmitter device. The vertical polarization signal includes a vertical polarization ID signal which identifies vertical polarization and a vertical polarization data signal which is a data signal. The horizontal polarization signal includes a horizontal polarization ID signal which identifies horizontal polarization and a horizontal polarization data signal which is a data signal. The vertical polarization ID signal and the horizontal polarization ID signal are transmitted simultaneously. The vertical polarization ID signal, the horizontal polarization ID signal, and the vertical polarization data signal are generated from signal sequences having orthogonal correlation.

Abstract: A channel response estimate is generated from a received signal that comprises two or more different pilot carriers in an Orthogonal Frequency Division Multiplexing (OFDM) communications system. This involves, for each of the carriers, determining a rotation amount that is at least in part a function of a frequency separation between two adjacent carriers, a delay spread of the channel, and a position of the carrier relative to other carriers within the received signal. The received signal is processed with a Fast Fourier Transform, thereby generating a processed signal. Prior to performing frequency interpolation as part of a channel estimation process, the processed signal is rotated by the rotation amount. The channel response is estimated by performing the channel estimation process at least in part on the rotated processed signal.

Abstract: A transmitting apparatus and receiving apparatus of a multi-carrier system using multiple antennas is proposed. An LCF encoder of the transmitting apparatus performs a liner precoding to input signals to be transmitted to a receiving apparatus using a liner complex matrix considering the number of multiple antennas and the number of subcarriers, and a subcarrier allocator respectively allocates a subcarrier to the signals liner-precoded by the LCF encoder. A transmitter respectively transmits the signals having a subcarrier allocated by the subcarrier allocator through the multiple antennas externally. A subcarrier de-allocator of a receiving apparatus extracts a liner-precoded signal by de-allocating a subcarrier allocated to the received signal. An LCF decoder outputs a bit reliability of the received signal to the liner-precoded signal extracted from the subcarrier de-allocator considering the number m of multiple antennas and the number n of subcarriers.

Abstract: A method for reducing signaling overhead in a multicarrier system with dynamic bit allocation per subcarrier and a corresponding transmitter/receiver device, are provided wherein an established bit allocation table (BAT) that is provided with an index (I) is stored in a BAT storage device (LUT). In order to reduce signaling overhead, only the corresponding index (I) of an existing bit allocation table is transmitted (S6).

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: Pilot, preamble and midamble patterns are provided that are particularly suited for four transmit antenna OFDM systems. Pilots are inserted in a scattered manner for each of the four antennas, either uncoded, space-time coded in pairs, space-time frequency coded in pairs, or space-time-frequency coded.

Abstract: Signal processing methods and apparatus which incorporate I/Q imbalance compensation based on most likely estimates of the I/Q imbalance between the I and Q components of a baseband signal are disclosed. In accordance with at least one disclosed embodiment of the invention, most likely estimates of the common phase error may also be used to compensate the initial channel estimates to further improve receiver performance. Though applicable to any multicarrier OFDM communications system, the disclosed methods and apparatus may be conveniently implemented in IEEE 802.11a, IEEE 802.11g, or 802.16a compliant wireless communications systems to reduce the effects of imbalanced I/Q components of baseband signals recovered from inbound RF signals, as well as counter residual frequency offset and phase noise potentially present in such baseband signals.

Abstract: A spread spectrum based multichannel modulation Ultra-Wideband (UWB) communication transceiver for indoor wireless operations is presented according to some embodiments. The spread spectrum based multichannels are orthogonal to each other and allow for an operation in parallel. The UWB communication transceiver can also avoid interference with WLAN 802.11a devices in the same environment. In addition, the UWB communication transceiver of the present invention can transmit and receive the scalability chip data rates from 650 Mcps to 7.15 Gcps.

Abstract: Systems and methods for bidirectional communication are provided. In one embodiment, a method for aligning communications from a plurality of remote units in a multipoint-to-point orthogonal frequency division multiplexed (OFDM) communications comprises sending a first signal from a host unit to a first remote unit; receiving a second signal transmitted from the first remote unit in response to the first signal; generating at least one timing adjustment signal based at least in part on a round trip delay between the sending of the first signal and the receiving of the second signal; transmitting the timing adjustment signal to the first remote unit; wherein the timing adjustment signal instructs the first remote unit to delay OFDM transmission of data to improve alignment of multiframes at the host unit when communications are received at the host unit from the plurality of remote units.

Abstract: A method of data communication. The method includes initially receiving one or more channel quality information signals from each wireless unit. The channel quality information may be received in response to the transmission of one or more pilot signals. Once the channel quality information signal(s) from each wireless unit are received, the method then includes selecting one or more transmit powers and one or more transmission rates for each wireless unit. Thereafter, one or more blocks of orthogonal continuous waveforms may be transmitted over a channel to each wireless unit using the selected transmit power and selected transmission rate.

Abstract: Systems and methods for receiving layered modulation for digital signals are presented. An exemplary apparatus comprises a tuner for receiving a layered signal and producing a layered in-phase signal and a layered quadrature signal therefrom, an analog-to-digital converter for digitizing the layered in-phase signal and the layered quadrature signal and a processor for decoding the layered in-phase signal and the layered quadrature signal to produce one or more discrete layer signals.

Abstract: Systems and methods for receiving non-coherent layered modulation signals are presented. An exemplary apparatus comprises a tuner for receiving a layered signal and producing a layered in-phase signal and a layered quadrature signal therefrom, an analog-to-digital converter for digitizing the layered in-phase signal and the layered quadrature signal, a processor for decoding the layered in-phase signal and the layered quadrature signal to produce a single layer in-phase signal and a single layer quadrature signal, a digital-to-analog encoder for converting the single layer in-phase signal and the single layer quadrature signal to a single layer in-phase analog signal and a single layer quadrature analog signal and a modulator for modulating the single layer in-phase analog signal and the single layer quadrature analog signal to produce a single layer signal.

Abstract: A transmitter for sending signals over wireless channels and a method of sending signals over wireless channels are described. The transmitter and the method are used to determine a transfer characteristic of an amplifier (8) in the transmitter. Symbols in the OFDM signals to be transmitted are multiplied by test signals at predefined points in time to compare the OFDM symbol, which has been multiplied by the test signal, upstream and downstream from the amplifier to determine the transfer characteristic of the amplifier (8). This transfer characteristic of the amplifier (8) is used by a predistorter (4) to predistort the signals according to this transfer characteristic. The test signal, which is generated by a signal generator (13), is input into a symbol of the fast information channel, the test signal having an amplitude which drives the multiplied symbol into the saturation range of the amplifier (8) with regard to its amplitude.

Abstract: An Orthogonal Frequency Division Multiplexing (OFDM) signal having a symbol defining a transmission unit is produced by dividing data streams into a plurality of carriers within a predetermined bandwidth and prepared with orthogonal modulation. A transform unit having at least two systems transforms the received OFDM signal to a carrier domain signal per symbol unit. A composite circuit segments the carrier units and adaptively composites the signal data which constitutes a plurality of different carriers transformed by a first system transform circuit and the signal data which constitutes a plurality of different carriers transformed by a second system transform circuit for each identical carrier in each system.

Abstract: A method and apparatus for decoding baseband OFDM signals include processing that begins by slicing each sub-carrier signal of the OFDM signal into a plurality of error terms. The particular number of error terms generated for each sub-carrier signal depends on the constellation size of the data being carried by each of the sub-carrier signals. The error terms for each sub-carrier signal corresponds to the nearest constellation point having a zero or one in the I or Q direction. The process continues by grouping individual error terms of the plurality of error terms for each sub-carrier signal to produce a plurality of error terms. The processing then continues by de-interleaving each of the plurality of error term groups to produce a corresponding plurality of de-interleaved error term groups.

Abstract: A method of processing a received OFDM symbol is disclosed. The received OFDM symbol has a symbol portion and a zero suffix portion. An information bearing portion of the zero suffix portion that is likely to contain information is determined and is combined with the symbol portion.

Abstract: In an OFDM transmission a transmission diversity technique is used without orthogonal signaling. The phases of the subcarriers received at the different antennas are compared by different techniques and then the phases of the signals for different antennas are adjusted for a subsequent transmission over the OFDM interface. The phase (and optionally amplitude) adjustment is calculated in only one (transmitting) side and no orthogonal signaling required. The number of antennas can be increased as much as necessary to get a sharper beam. The negative effects of fading and interference can be reduced so that at same time a down link transmission power can be reduced.

Abstract: The invention relates to a method and to a modulator for modulating signals. The signals are to be transmitted by a device in packets via an air interface. Each packet is supposed to comprise at least one entity of at least two different entities, which different entities are employed for transmitting signals representing different kinds of information. In order to enable a higher data rate, signals that are to be transmitted in at least one of said different entities are modulated with a first set of values of at least one modulation parameter of a selected modulation scheme. Further, signals that are to be transmitted in at least one other of said different entities are modulated with a second set of values of said at least one modulation parameter, said second set of values comprising less values than said first set of values.

Abstract: A modulation and demodulation system is provided. The system uses n sub-carrier frequencies and an oversampling positive integer and includes a modulation circuit and a demodulation circuit. The modulation circuit includes a modulation ROM that stores columns of elements independently in a modulation ROM matrix. The demodulation circuit includes 2n numbers of a ROM1 that stores elements of a combined matrix. The combined matrix is generated by combining a number of inverse matrices where the inverse matrices are generated from the modulation ROM.

Abstract: Methods and systems for forward-looking tone allocation are provided. In one embodiment, a method for an orthogonal frequency division multiplexing (OFDM) multipoint-to-point communications system comprises: establishing communication between a plurality of remote units and a host unit, the remote units communicatively coupled to the host in a multipoint-to-point configuration; transmitting a plurality of tones from the remote units, such that tones from more than one remote unit are simultaneously received at the host, the tones modulated with upstream information using OFDM; adjusting at least one characteristic of at least one tone at least one remote unit, in response to adjustment commands from the host, such that the orthogonality of the simultaneously received tones is improved as received at the host unit; and dynamically switching modulation from at least a first tone of the plurality of tones to a second tone based on an error-rate history of the second tone.

Abstract: A technique for Crest Factor reduction of multi-carrier signals using phase rotation is described. The multi-carrier signal could be in digital baseband, analog baseband, or analog RF (radio frequency). The multi-carrier signal is converted to individual baseband representatives before each individual baseband signal being phase rotated according to an algorithm which maintains the crest factor to a pre-defined value. The algorithm uses a deterministic phase rotation technique and each phase rotated baseband signals will be individually filtered to remove the unwanted signals. The phase rotated and filtered baseband signals are then up converted and combined to reconstruct the multi-carrier signal. The crest factor reduction is limited by the in band distortion introduced to each individual signal.

Abstract: Methods and systems for adaptive modulation are provided. In one embodiment, a method for a plurality of remote units of an orthogonal frequency division multiplexing multipoint-to-point communications system comprises: establishing communication between a plurality of remote units and a host unit, the plurality of remote units communicatively coupled to the host unit in a multipoint-to-point configuration; transmitting a plurality of tones from the plurality of the remote units such that tones from more than one remote unit are simultaneously received at the host unit, the plurality of tones modulated with upstream information using orthogonal frequency division multiplexing; modulating up to a plurality of tones using a first modulation scheme when transmitting a first type of upstream information; and modulating up to a plurality of tones using a second modulation scheme when transmitting a second type of upstream information.

Abstract: A wireless communications network, including a base station (10) and wireless units (UE), is disclosed. The wireless units (UE) request a connection with the base station (10) by the transmission of a preamble within time slots designated by the base station (10). The disclosed preambles are Walsh Hadamard code symbols, repeated a number of times so as to have the same length as a cell-specific scrambling code. The wireless unit (UE) requesting a connection pseudo-randomly selects a time slot from those available, and one of the Walsh Hadamard code symbols, replicates the code symbol into a spread interleaved bitstream, scrambles this bitstream and transmits it to the base station (10). Upon receipt, the base station (10) applies the incoming bitstream to a matched filter (98) to descramble the signal, following which the symbol is de-interleaved by way of a sequence of delay lines (100).

Abstract: An OFDM transmitter includes a lookup table for storing at least two groups of data digits associated with different respective characteristic frequencies (e.g. 3960 MHz, 5016 MHz). An addressing circuit addresses the lookup table and repeatedly and sequentially selects the groups of data digits. The data digits of the selected group are output sequentially. The output sequence of data digits is converted to analog form, and each group of data digits, when output and converted to analog form, provides a carrier signal at the characteristic frequency associated with that group. The carrier signal is modulated in accordance with an information signal to provide a transmission signal.

Abstract: Interleaving circuit for a multiband OFDM (orthogonal frequency division multiplexing) transceiver of a ultra wide band wireless personal access network transmitting OFDM modulated symbols, wherein each OFDM symbol consists of a predetermined number (NCBPS) of encoded bits, said interleaving circuit comprising a symbol interleaving unit which receives an input bitstream of encoded bits and permutes adjacent bits of said input bitstream across different OFDM symbols; an intra-symbol tone interleaving unit which receives the bits permuted by said symbol interleaving unit and permutes adjacent bits of each OFDM symbol across uncorrelated data sub-carriers; and an intra-symbol cyclic shift unit which shifts cyclically NCBPS bits of each OFDM symbol in response to a shift value (K) which is changed between adjacent OFDM symbols.

Abstract: In a transmitting/receiving concept a redundancy-adding encoder is used in order to obtain two data streams for different transmitters. In the receiver, the receiving signal is sampled by a first sampler synchronous to the first transmitter and is output by a second sampler synchronous to the second transmitter in order to obtain a first and a second receiving signal which are fed to a trellis decoder to obtain a decoded first and second receiving subgroup of code units which are again fed to a calculating means in order to calculate the interference signals which are then combined with the corresponding receiving signals for an interference reduction. The iterative concept enables an interference reduction for receiving signal generated by two spatially separated transmitters. The receiver concept shows a quick convergence and thus enables the two transmitters to transmit in the same frequency band.

Abstract: The present invention provides a method and apparatus for assigning uplink acknowledgement channels in scheduled packet data systems is provided. The method includes providing at least one message indicating that at least one packet is scheduled to be provided to at least one mobile unit over a downlink. The message also indicates at least one time-frequency resource for providing acknowledgment of the at least one packet on an uplink.

Abstract: Provided are delta-predicted frequency offset compensation apparatus and method that estimates an offset delta of forthcoming symbols by using a principle that the offset delta of a symbol in a previous section is almost the same as an offset delta of some forthcoming symbols. The offset compensation method of the present research includes the steps of: a) estimating a frequency offset of a communication system based on an estimation period and estimation algorithm; b) outputting a compensation value for offset compensation through a feedback loop by considering the frequency offset value estimated based on the estimation period and the frequency offset delta estimated based on the estimation period and delay interval; and c) shifting the phase of a signal by as much as the offset corresponding to an input signal of the communication system to compensate the symbol for the frequency offset.

Abstract: Adaptive modulation/demodulation method in a radio communication system is provided. A modulation multi-level number in a transmission device and a demodulation multi-level number in a reception device are judged independently from each other according to a propagation condition and communication is performed by controlling the likelihood when the multi-level numbers of the transmission side and the reception side are different. The reception device can perform operation by controlling likelihood information on lower bit of the multi-level modulation even when the modulation multi-level number and the demodulation multi-level number used at the transmission side are different. Moreover, the transmission device and the reception device independently decide the modulation multi-level number and the demodulation multi-level number, thereby following an instantaneous propagation fluctuation and improving the throughput.

Abstract: A multiplexing scheme to select either an I component or a Q component for input to I channel and Q channel inputs of a baseband receiver. The selection of which of the I or Q component to place on the I channel input and which other to place on the Q channel input is based on, there being a correct relationship of the I and Q components received from a RF processing stage of a wireless communication device or if the I and Q components have incorrect relationship because they are interchanged.

Abstract: Emergency Location Transceivers (ELT) and communication transceivers (transmitters and receivers) for reception and demodulation of location finder signals, Global Positioning System (GPS) satellite signals and non GPS satellite location finder and other location finder signals. The received location finder signals are demodulated to location finder baseband signals. Baseband signal processors for processing single or a plurality of input signals for providing Orthogonal Frequency Division Multiplex (OFDM) baseband signals, filtered signals, cross-correlated shaped in-phase and quadrature-phase baseband signals and spread spectrum signals. Signal modulators for modulating the processed signals and for providing the modulated signals to the signal transmitter for transmission of the modulated signals. Emergency receiver systems for reception, demodulation and processing of the modulated transmitted signals.