Abstract: Embodiments of an apparatus, system and method are described for a base station. Notification from a mobile station in a network may be received. A multi-carrier advertisement with a base station multi-carrier configuration may be sent. The base station multi-carrier configuration may include at least one carrier index associated with a carrier frequency operated on by the base station. Other embodiments are described and claimed.

Abstract: The method for controlling signal transmission includes: determining the first reference variable according to the number of transition points from downlink to uplink in a wireless frame of the system and the system frame number (S502); determining the second reference variable according to the number of transition points from downlink to uplink in a wireless frame and the time slot number (S504); determining the third reference variable according to the sub-frame offset of the signal (S506); and determining signal transmission times according to the first reference variable, the second reference variable and the third reference variable, so as to control the signal transmission (S508).

Abstract: An apparatus and method for generating a signal for transmission in a single-carrier communication system are disclosed. The apparatus comprises a reference signal inserter, which multiplexes data symbols with reference signal symbols in time domain to form a plurality of symbol blocks as the signal for transmission, wherein the plurality of symbol blocks include symbol blocks of a first type and symbol blocks of a second type, wherein each of the symbol blocks of the first type includes only data symbols, and wherein each of the symbol blocks of the second type includes both data symbols and reference signal symbols.

Abstract: A communication apparatus repeatedly outputs a first multi-carrier signal SS during predetermined periods T1, T2, T3, . . . , and outputs a second multi-carrier signal RS whose phase vector is different from that of the first multi-carrier signal SS, at a predetermined timing based on the first multi-carrier signal SS. The communication apparatus further detects the second multi-carrier signal RS output from another communication apparatus, which uses a different communication method from the communication apparatus. Accordingly, both communication apparatuses can differentiate the first multi-carrier signal SS from the second multi-carrier signal RS without performing relatively cumbersome modulation and other processes.

Abstract: A method for transmitting and receiving signals using multi-band Radio Frequencies (RFs) is provided. The method includes transmitting/receiving control information identifying a subsidiary carrier frequency band for a user equipment via a primary carrier frequency band of the user equipment, wherein the control information includes information of a second ID assigned to a first ID of the subsidiary carrier frequency band among a plurality of first IDs, the first ID identifying the subsidiary carrier frequency band in the physical layer and the second ID identifying the subsidiary carrier frequency band in the specific layer.

Abstract: A method for efficiently performing an initial access in an MS in a multi-carrier broadband wireless access system is disclosed. The method includes scanning a plurality of carriers supported by a BS, and selecting one of the scanned carriers as a first carrier and receiving an SFH of the first carrier. The SFH of the first carrier includes at least one of a field indicating load status of the first carrier and recommended network entry carrier information including information about a second carrier in good load status.

Abstract: A power line communication method for realizing data communication between at least one first or sending power line communication partner device and at least one second or receiving power line communication partner device. The method checks transmission conditions of a plurality of possible communication channels, thereby generating transmission condition data descriptive for the communication conditions of the respective possible communication channels. Additionally, communication conditions of the plurality of possible communication channels are selected as actual communication conditions based on the transmission condition data.

Abstract: An apparatus and method for transmitting/receiving an S-SCH in an Institute of Electrical and Electronics Engineers (IEEE) 802.16m wireless communication system are provided. A method for transmitting, by a transmitter, a Secondary Synchronization CHannel (S-SCH) in a communication system includes generating a sequence depending on a cell IDentification (ID), determining a subcarrier set comprising subcarriers to map the generated sequence, based on a Fast Fourier Transform (FFT) size and a segment ID, and mapping the generated sequence to the subcarriers of the determined subcarrier set.

Abstract: A UE in a wireless communication network transmits succinct, direct channel state information to the network, enabling coordinated multipoint calculations such as joint processing, without substantially increasing uplink overhead. The UE receives and processes reference symbols over a set of non-uniformly spaced sub-carriers, selected according to a scheme synchronized to the network. The frequency response for each selected sub-carrier is estimated conventionally, and the results quantized and transmitted to the network on an uplink control channel. The non-uniform sub-carrier selection may be synchronized to the network in a variety of ways.

Abstract: A power line communication method for realizing data communication between at least one first or sending power line communication partner device and at least one second or receiving power line communication partner device. The method checks transmission conditions of a plurality of possible communication channels, thereby generating transmission condition data descriptive for the communication conditions of the respective possible communication channels. Additionally, communication conditions of the plurality of possible communication channels are selected as actual communication conditions based on the transmission condition data.

Abstract: A method and apparatus for transmitting and receiving a digital signal using an orthogonal frequency division multiplexing (OFDM) communication system are provided. In this method, subcarriers are split into a plurality of subcarrier groups according to available frequency bandwidths and are respectively transmitted in a transmitting portion and the subcarrier groups are combined and are restored to the original signal in a receiving portion. Therefore, wireless resources may be used efficiently by combining with cognitive radio technology.

Abstract: A transmission method for transmitting modulation signals of a plurality of channels to the same frequency band from a plurality of antennas. At the time when a symbol used for demodulation is inserted in a channel, in another channel symbol, the same phase and quadrature signals in the in-phase-quadrature plane are made to be zero signals. Thus, a plurality of modulation signals are multiplexed and transmitted and the transmitted multiplexed modulation signals are demultiplexed and demodulated at a reception apparatus, thereby improving the data transmission rate.

Abstract: A power line communication method for realizing data communication between at least one first or sending power line communication partner device and at least one second or receiving power line communication partner device. The method checks transmission conditions of a plurality of possible communication channels, thereby generating transmission condition data descriptive for the communication conditions of the respective possible communication channels. Additionally, communication conditions of the plurality of possible communication channels are selected as actual communication conditions based on the transmission condition data.

Abstract: A method for mapping a physical downlink control format indicator channel to physical resources includes the steps that 16 modulated data y(0), y(1), . . . , y(15) of a downlink control signaling indicator channel in an LTE system are divided into 4 groups in order and mapped by groups, which allows the downlink control format indicator channel to be mapped exactly to the continuous 4 resource elements recombined by resources which are divided among all system physical resources except the pilots according to such continuous 4 resource elements. By defining group mapping rules, this method can offer the maximum gain of frequency selectivity.

Abstract: A multicarrier data transmission scheme is provided. According to the provided scheme, a radio transmitter encodes data bits with different degrees, the degree of an encoded data bit being defined by the number of parity check equations protecting the data bit. The data bits are preferably encoded with an irregular low-density parity check (LDPC) code. The encoded data bits are then mapped to symbols. The symbols are allocated to subcarriers of a multicarrier radio signal on the basis of channel state information obtained from the radio receiver and the degree used with respect to each symbol. On the basis of the channel state information, a number of subcarriers are truncated due to high attenuation, and the number of subcarriers to be truncated relative to the total number of subcarriers is substantially fixed. The available transmit power to the non-truncated subcarriers. The multicarrier signal comprising symbols on the non-truncated subcarriers is then transmitted to the radio receiver.

Abstract: A base station allowing mobile stations to efficiently remove interference signals. In this base station (100), an encoding part (101) performs an error correction encoding of transport data to generate a bit sequence comprising systematic bits and parity bits; a repetition part (102) repeats, as a repetition subject, only the parity bits out of the plurality of bits included in the bit sequence, which is generated by the encoding part (101), so as to perform a rate matching; a modulating part (103) modulates, after the repetition, the bit sequence to generate symbols; an S/P part (104) parallel converts the symbols serially inputted from the modulating part (103) and then outputs them to an IFFT part (105); and the IFFT part (105) performs an IFFT processing of the symbols inputted from the S/P part (104) and then maps them onto subcarriers in accordance with a predetermined mapping pattern, thereby generating OFDM symbols.

Abstract: A method and system for communicating an ultra-wideband signal carrying a combined digital signal that represents digital signals for multiple communication channels of a wireless communication system. A distributed antenna system includes multiple remote antenna entities. Each remote antenna entity may include an ultra-wideband transceiver for sending or receiving the ultra-wideband signal. The multiple remote antenna entities may be spaced apart within an indoor premises so as to extend cell coverage of a base transceiver station. The ultra-wideband signal may be transmitted in a forward-link direction towards one or more wireless communication devices or in a reverse-link direction towards the base transceiver station. An aggregator within a remote antenna entity may aggregate multiple combined digital signals so as to form an aggregated combined digital signal that may be transmitted in a reverse-link direction towards the base transceiver station.

Abstract: Methods and systems for utilizing a single PLL to clock an array of DDFS for multi-protocol applications are disclosed. Aspects of one method may include generating a first signal for use in generating a plurality of local oscillator (LO) signals. The first signal may be communicated to a plurality of LO generators. Each of the LO signals may be generated independently of each other by a corresponding one of the LO generators. Each of the LO signals may be communicated to one or more mixers, where each mixer may perform down-conversion or up-conversion. A LO generator may utilize, for example, a DDFS or a digital delay circuit. A frequency of a LO signal may be varied by adjusting a divide factor for a divider that generates a reference clock for the DDFS or for a divider that generates a second signal used for mixing with a signal generated by the DDFS. The LO signal frequency may also be varied by adjusting frequency control words received by a DDFS.

Abstract: A method for transmitting an uplink sounding reference signal includes indexing Single Carrier Frequency Division Multiple Access (SC-FDMA) symbols within a single radio frame for transmitting a Sounding Reference Signal (SRS) as a number k, and calculating a value of nSRS according to number k and an index number of the radio frames for transmitting the SRS, determining an index number of a frequency-domain start sub-carrier mapped from time-domain SRS symbol with nSRS, and transmitting the SRS through the sub-carrier with the determined index number determined. Before transmitting the SRS, the start frequency position for SRS should be changed according to the specific frequency-hop pattern to guarantee that the UE may uniformly sound the entire SRS frequency-hop bandwidth after multiple soundings.

Abstract: An apparatus and method for frequency division and filtering are provided. The apparatus includes a memory unit, an extrema calculation unit, and an envelope calculation unit. The memory unit is for storing sample data. The extrema calculation unit is for outputting and storing a number of maximum values and a number of minimum values to the memory unit according to the sample data. The envelope calculation unit is for calculating a mean envelope according to the maximum values and the minimum values, wherein within a duration when the envelope calculation unit respectively calculates an upper envelope and a lower envelope according to the maximum values and the minimum values, the envelope calculation unit outputs a value of the mean envelope to the memory unit according to a value of the upper envelope and a value of the lower envelope with respect to a corresponding identical address.

Abstract: A communication apparatus repeatedly outputs a first multi-carrier signal SS during predetermined periods T1, T2, T3, . . . , and outputs a second multi-carrier signal RS whose phase vector is different from that of the first multi-carrier signal SS, at a predetermined timing based on the first multi-carrier signal SS. The communication apparatus further detects the second multi-carrier signal RS output from another communication apparatus, which uses a different communication method from the communication apparatus. Accordingly, both communication apparatuses can differentiate the first multi-carrier signal SS from the second multi-carrier signal RS without performing relatively cumbersome modulation and other processes.

Abstract: A power line communication method for realizing data communication between at least one first or sending power line communication partner device and at least one second or receiving power line communication partner device. The method checks transmission conditions of a plurality of possible communication channels, thereby generating transmission condition data descriptive for the communication conditions of the respective possible communication channels. Additionally, communication conditions of the plurality of possible communication channels are selected as actual communication conditions based on the transmission condition data.

Abstract: In one embodiment, a network node includes a lookup table configured to store one or more of the following frequency domain bit sequences: i) x010101000110xxxxxxx011000000000; ii) x1011000111000000011011110xxxxxxxxxxxxx0110111001101001010111010; iii) x0011011011111010011101111xxxxxxxxxxxxx0111010010111110000000101; iv) x000000011000100110100100xxxxxxxxxxxxx1011011110000110101011100; and v) x1000010000110111100000110xxxxxxxxxxxxx1100110011101101111110110. The node includes a processing channel configured to generate a preamble including at least one of the frequency domain bit sequences, and a transmitter configured to transmit the preamble and a data packet over a communication channel.

Abstract: Disclosed is a downlink signal configuring method and device, and synchronization and cell search method and device using the same in a mobile communication system. A downlink frame has plural symbols into which pilot subcarriers are distributively arranged with respect to time and frequency axes. Initial symbol synchronization and initial frequency synchronization are estimated by using a position at which autocorrelation of a cyclic prefix of a downlink signal and a valid symbol of the downlink is maximized, and cell search and integer-times frequency synchronization are estimated by using pilot subcarriers included in the estimated symbol. Fine symbol synchronization, fine frequency synchronization, and downlink frame synchronization is estimated by using an estimated cell search result.

Abstract: Inter-carrier interference (ICI) in a kth sub-carrier of an orthogonal frequency division multiplexing (OFDM) signal received at time t is reduced, wherein the received OFDM signal comprises a plurality of sub-carriers. This is achieved by generating a self-interference term, ICIk?L,k?L, for a signal received on sub-carrier k?L, wherein L ? [ . . . , ?3,?2,?1,1,2,3, . . . ], and wherein the self-interference term is an estimate of the data received at time t on the sub-carrier k?L, weighted by a rate of change of the channel through which sub-carrier k?L passes at time t. An ICI cancellation coefficient, GL is obtained, and an estimated ICI term is generated by adjusting the self-interference term, ICIk?L,k?L, by an amount based on the ICI cancellation coefficient, GL. The estimated ICI term is then subtracted from a term representing a signal received on the kth sub-carrier at time t.

Abstract: A method for transmitting an uplink sounding reference signal includes indexing Single Carrier Frequency Division Multiple Access (SC-FDMA) symbols within a single radio frame for transmitting a Sounding Reference Signal (SRS) as a number k, and calculating a value of nSRS according to number k and an index number of the radio frames for transmitting the SRS, determining an index number of a frequency-domain start sub-carrier mapped from time-domain SRS symbol with nSRS, and transmitting the SRS through the sub-carrier with the determined index number determined. Before transmitting the SRS, the start frequency position for SRS should be changed according to the specific frequency-hop pattern to guarantee that the UE may uniformly sound the entire SRS frequency-hop bandwidth after multiple soundings.

Abstract: A correlation canceller modulates a communication signal over a plurality of channels and an epoch aperture by a plurality of interference response signals corresponding to linear response by one or more filtering effects to generate an inversely correlated communication signal.

Abstract: A Tree-structured multicarrier multiple access communication system in a multiple access environment having a number of interfering signals. In one embodiment an environment estimator estimates and tracks the number of interfering signals of the environment. A code selector determines an optimal spreading code represented by the environment, and identifies an actual spreading code that is closest to the optimal spreading code. A signal transmitter can then be used to transmit a multicarrier multiple access signals in accordance with the actual spreading code identified. On the receiver side, a multiuser detector (MUD) module performs tree structured multiuser detection signal processing, and produces a bit stream for each interfering signal.

Abstract: The position of a specific pattern such as a known symbol in a signal such as an OFDM signal is estimated with high accuracy. An effective symbol extraction section extracts a known symbol (preamble) as an effective symbol from a signal to be measured according to an approximate position of the known symbol. A mixer determines the product of the frequency spectrum of the extracted effective symbol by the result of the conversion performed by a complex conjugate conversion section from the frequency spectrum of the known symbol into the conjugate complex. A phase shift amount measuring section measures the phase shift amount ?? of the product determined by the mixer. A precision pattern position measuring section measures the difference between the position of the known symbol and its approximate position on the basis of the phase shift amount.

Abstract: A system for communicating includes a transmitter that has an encoder and baseband modulator that encodes and modulates a sequence of data symbols as a payload data constellation to be communicated. A PN sequence generator and baseband modulator form a pilot signal as a training sequence with a periodically repeating spread spectrum sequence. A circuit superimposes the pilot signal over the sequence of data symbols to form a composite communication signal that is transmitted. A receiver receives the composite communication signal and extracts the pilot signal from the composite communication signal.

Abstract: In a wireless local area network (WLAN) that includes high-throughput communication devices with multiple antennas and legacy communication devices with single antennas, training tones are transmitted over a plurality of spatial channels during a first portion of an orthogonal frequency division multiplexed (OFDM) packet-training preamble. The training tones are interspersed among subcarrier frequencies of the spatial channels. The training tones are retransmitted during a second portion of the packet-training preamble. The training tones are shifted among the subcarrier frequencies of the spatial channels during the retransmission allowing a high-throughput receiving station to perform a channel estimation on different subcarrier frequencies of the spatial channels. The legacy communication devices may receive and process the training tones and may set their network allocation vector to refrain from communicating during a subsequent interval.

Abstract: A correlation canceller modulates a communication signal over a plurality of channels and an epoch aperture by a plurality of interference response signals corresponding to linear response by one or more filtering effects to generate an inversely correlated communication signal.

Abstract: A frequency interpolation apparatus is provided which reproduces a signal similar to an original signal by approximately recovering suppressed frequency components, from an input signal having the suppressed frequency components in a specific frequency band of the original signal. The input signal is divided into a plurality of signal component sets each having frequency components in a frequency band among a plurality of frequency bands, and a signal component set in the band with the suppressed signal components is synthesized from the plurality of divided signal component sets and added to the input signal. Each of the plurality of divided signal component sets is frequency-converted to a signal component set in the same frequency band, and the signal component set in the band with the suppressed signal components is synthesized through linear combination of the frequency-converted signal component sets.

Abstract: New version devices of a home phone line network may operate on a first carrier frequency (within the new version frequency band) while old version devices may operate at a second carrier frequency (within the old version frequency band). Preamble, header, and trailer portions of a new version signal include a plurality of spectral copies of a baseband modulated signal. One or more of these spectral copies of the baseband modulated signal is/are indistinguishable from corresponding components of an old version signal. The new version signal is transmit filtered to have a negatively sloping power spectral density in order to maintain a constant power level in relation to old version signals and to have slope that is opposite of binder crosstalk so as to form, with the average crosstalk, a constant level white noise floor.

Abstract: A communication system is provided herein for transmitting frames across a channel. The frames may be transmitted in single-input, single-output (SISO) and/or multi-input, multi-output (MIMO) communication systems. One such frame includes at least one training symbol, each having a cyclic prefix and a training block. The time length NI of the training block is equal to an integer fraction I of the time length of a data block, i.e., NI=N/I. Furthermore, the time length G of the cyclic prefix is an integer fraction of the time length NI. For example, G may be equal to NI/4 or 25% of NI. The training symbols provide coarse and fine time synchronization, coarse and fine frequency synchronization, channel estimation, and noise variance estimation.

Abstract: A digital communication system (20) in which a signal constellation (30) of a dimensionality of at least four is used, with distance properties chosen to reduce the bit error rate compared to that of digital communication systems using signal constellations of half the dimensionality. A symbol generator (21) uses the higher dimensional signal constellation (30), or any orthogonal transformation of the higher dimensional signal constellation (30), to translate a bit stream into a stream of higher dimensional symbols, which it then provides to a modulator (22). The modulator (22) transmits each higher dimensional symbol in at least two parts, using a modulation scheme according to the prior art, such as QAM or QPSK.

Abstract: A method of correctly estimating the frequency offset when the CPE modem has already acquired and is tracking the OFDM burst boundaries in an OFDM-based, wireless communication system. CPS data in an OFDM-based, wireless communication system is modulated as QPSK data in the training tones of the data burst. As long as some bursts have the CPS data modulation and some bursts do not have the CPS data modulation, the CPS data can be recovered. A slip results when there is a linear phase difference across the tones (after the FFT) between the current and the previous burst. This linear phase difference is generally taken care of by the channel estimation obtained using the pilot tones. This phase difference is however, now compensated for correct frequency offset estimation which occurs before the channel estimation and CPS decoding steps.

Abstract: For synchronisation purposes, a transmitter (TX) multiplexes a pilot carrier with carriers whereon data elements (DATA) are modulated, and transmits the pilot carrier together with the modulated carriers to a receiver (RX). The immunity of the pilot carrier for interferers, such as radio amateur signals, is improved by modulating the pilot carrier with a non-constant signal, for instance a random signal, an alternating signal or even scrambled data elements (DATA), before transmission thereof. Since demodulation of the pilot carrier in the receiver (RX) and averageing successive demodulated pilot carriers reduces the effect of the interference induced on the non-constantly modulated pilot carrier, the degradation of the synchronisation between transmitter (TX) and receiver (RX) is reduced significantly.

Abstract: Various methods and systems efficiently implement broadband multi-carrier communication systems. The invention exploits the structural properties of a frequency-domain channel estimator and transforms it into the time domain. This allows the sharing of certain blocks of hardware (e.g., matched filters otherwise used for timing acquisition) which results in significant reduction of complexity.

Abstract: A transmission apparatus of orthogonal frequency division multiplexing for multiplexing a plurality of carriers orthogonal to one another to transmit a modulated signal. The transmission apparatus includes a first modulator for outputting a code modulated in accordance a modulation scheme which can be applied with a synchronous detection for demodulation, a second modulator for outputting a code modulated in accordance with a modulation scheme different from the modulation scheme associated with the first modulator, and a distributing circuit for distributing the codes modulated by the first and second modulators to a plurality of carriers. The distributing circuit distributes the code modulated by the second modulator to all or some of carriers existing within a predetermined number of columns from at least one of both end regions of a signal transmission frequency band, and the code modulated by the first modulator to the remaining carriers.

Abstract: An improved transmitter apparatus, a receiver apparatus and a base station implemented with the transmitter and receiver apparatuses are described. These apparatuses and the base station serves to establish communication by making use of an orthogonal frequency division demultiplexing demodulation and an inverse spectrum spreading demodulation in combination. The communication coverage thereof can be expaned by making use of an orthogonal frequency division demultiplexing demodulation and an inverse spectrum spreading demodulation in combination.

Abstract: For synchronization purposes, a transmitter (TX) multiplexes a pilot carrier with carriers whereon data elements (DATA) are modulated, and transmits the pilot carrier together with the modulated carriers to a receiver (RX). The immunity of the pilot carrier for interferers, such as radio amateur signals, is improved by modulating the pilot carrier with a non-constant signal, for instance a random signal, an alternating signal or even scrambled data elements (DATA), before transmission thereof. Since demodulation of the pilot carrier in the receiver (RX) and averaging successive demodulated pilot carriers reduces the effect of the interference induced on the non-constantly modulated pilot carrier, the degradation of the synchronization between transmitter (TX and receiver (RX) is reduced significantly.

Abstract: A method of transmitting data on multiple carriers is disclosed, the method consisting, on a transmitter side, of binary to signal coding of the data to be transmitted so as to form modulation signals, of modulating a plurality of sub-carriers with the modulation signals as to form symbols, referred to as OFDM symbols, and then of transmitting, over a channel between the transmitter and a receiver, the OFDM symbols at a rate which is related to a sampling frequency referred to as the transmitter sampling frequency, and, on the receiver side, of determining, from a clock signal at a frequency related to a sampling frequency referred to as the receiver sampling frequency, an analysis window for the signal received from the transmitter so as to form a block of samples, and of estimating the transmitted modulation signals by demodulating the sub-carriers for the block of samples under consideration.

Abstract: A gradient sensitivity based method is described for reducing Peak to Average Power Ratio in multicarrier communication systems. The method involves definition of a differentiable penalty function which has non-zero values whenever there is a peak violation. The gradient of the function with respect to the symbol magnitudes and phases is evaluated at the given symbol vector. Symbol perturbations are computed in the opposite direction of the gradient in such a way that the peaks are reduced and the amount of errors introduced in the symbols is not large enough to affect the decoding process. In order to reduce computation, a variant of the method is proposed where a peak reduction kernel is precomputed and stored. The kernel is rotated to the location of the peak and added with proper sign to reduce PAR.

Abstract: An orthogonal frequency division multiplexed signal generator comprises a data sequence conversion means, a power changing means, an inverse discrete Fourier transform part, and an orthogonal modulation means, and modulates a first data and a second data using modulation systems independent of each other, into an orthogonal frequency division multiplexed signal. The data sequence conversion means arranges the first data to be transmitted, in a predetermined order correspondingly to two or more sub-carriers orthogonal to each other on a frequency axis. The power changing means changes powers of the sub-carriers in accordance with the second data to be transmitted which is independent of the first data. The inverse discrete Fourier transform means generates a time-base waveform by synthesizing the individual sub-carriers. The orthogonal modulation means performs orthogonal modulation on a real axis signal and an imaginary axis signal which are orthogonal to each other to synthesize them.

Abstract: This invention pertains to multicarrier systems where the Peak power to Average power Ratio (PAR) is generally high, and where the system has a Forward Error Correction (FEC) mechanism. A peak detection mechanism, a procedure for choosing a subcarrier to be modified and a symbol modifier scheme are disclosed for lowering the peak power of a signal while minimizing coding errors. The peak detector uses a threshold for determining whether the PAR reduction is to be applied. A subcarrier symbol(s) to be modified is identified depending on the number of peaks in a frame, by determining the subcarrier symbol which has the maximum effect on the peaks in the frame. One method chooses the subcarrier with the greatest overall effect on a peak in the frame, a second method selects the subcarrier that gives the minimum sum of residual peaks, and a third method is limited to situations where there are only two peaks.

Abstract: A method for providing Digital Subscriber Line (DSL) service to a group of subscribers over respective subscriber loops in the presence of another, existing digital network service provided on at least some of the subscriber loops. Lower, middle and upper frequency bands are assigned for transmission over the subscriber loops, such that the existing digital network service is provided on the lower band. DSL signals are transmitted downstream on the upper band and are received upstream on the middle band, generally without transmitting or receiving DSL signals on the lower band, over those subscriber loops on which the existing digital network service, is provided. Over those subscriber loops on which the existing digital network service is not provided, the DSL signals are transmitted downstream on the lower and upper bands and are received upstream on the lower and middle bands.

Abstract: A receiver receives an analog signal that is modulated from transmission data using a multi-carrier method, and a gain controller controls a gain of the received analog signal. An AD converter samples the received analog signal processed by the gain controller so that an FFT unit can perform a Fourier transform on the sampling data and demodulate the data into carrier units. Then, a sync symbol, which is transmitted from an opposing side after the data communication is initiated using the multi-carrier method, is retrieved from the demodulated data. By analyzing individual signal value of a plurality of carriers within the retrieved sync symbol, an appropriate gain control is instructed for the gain controller.

Abstract: In all wireless systems, the first operation that must take place at the receiver is the acquisition of the carrier and timing. OFDM systems are particularly sensitive to carrier offsets since these can introduce inter-carrier interference and loss of signal power. An algorithm, termed modulo-sub-carrier (ModSC), which can estimate the local oscillator offset in a fast and efficient manner has been devised. The carrier offset can be brought to within one half the carrier spacing within 1 to 10 OFDM symbols. By inserting a null in the center carrier, carrier acquisition can be easily accomplished by locating this null in the FFT bins at the receiver. The offset of this null from the designed position indicates the local oscillator offset in units of number of sub-carriers. An additional carrier tracking algorithm is used to estimate the offset within one half the inter-carrier spacing. Together, the ModSC and carrier tracking algorithms completely estimate the local oscillator offset.

Abstract: A method for transmission of data in a digital audio broadcasting system includes the steps of providing a plurality of orthogonal frequency division multiplexed sub-carriers, with the sub-carriers including data sub-carriers and reference sub-carriers, and modulating the data sub-carriers with a digital signal representative of information to be transmitted. The reference sub-carriers are modulated with a sequence of timing bits, wherein the sequence of timing bits includes an unambiguous block synchronization word, and the number of bits comprising the block synchronization word is less than one half of the number of bits in said timing sequence. Then the orthogonal frequency division multiplexed sub-carriers are transmitted. Receivers that differentially detect the block synchronization word and use the block synchronization word to coherently detect the digital signal representative of information to be transmitted are also included.