1039 results about "Frequency-division multiplexing" patented technology

A facility transport system for transporting high speed Ethernet data over digital subscriber lines. The system, referred to as 100BaseS, is capable of transmitting 100 Mbps Ethernet over existing copper infrastructure up to distances of approximately 400 meters. The system achieves bit rates from 25 to 100 Mbps in increments of 25 Mbps with each 25 Mbps increment utilizing a separate copper wire pair. Each pair used provides a bidirectional 25 Mbps link with four copper wire pair connections providing 4×25 Mbps downstream channels and 4×25 Mbps upstream channels. The system utilizes framing circuitry to adapt the 100BaseT input data signal to up to four separate output signals. A DSL Ethernet Port card couples the modem to each twisted pair used. Each DSL Ethernet Port card comprises modem transmitter and receiver circuitry for sending and receiving 100BaseS signals onto twisted pair wires. The system utilizes QAM in combination with frequency division multiplexing (FDM) to separate downstream channels from upstream channels and to separate both the downstream and the upstream channels from POTS and ISDN signals.

A class of bandwidth reduction techniques are used develop a broad class of modulation types collectively called SSB-FM. These signals can be used to construct communication systems that provide bandwidth-normalized performance gains of 10 dB or more when compared to popular prior art modulation methods. An aspect of the invention involves mapping trellis paths in a complex signal space onto corresponding real-valued trellis signals with desirable spectral properties. The invention can be used map continuous phase modulated (CPM) signals onto simpler amplitude-modulated trellis signals having double the channel capacity of prior art CPM signals. Multi-amplitude signaling and frequency division multiplexing may also be incorporated to further accommodate more information per symbol.

A communications device includes a demapping and demodulation circuit and processes an OFDM communications signal that includes modulated subcarriers carrying communications data forming a data payload and modulated subcarriers carrying a training sequence forming a preamble. Those OFDM subcarriers carrying the training sequence have a sample for each subcarrier at a frequency bin using evenly spaced, equal amplitude subcarriers that have a set phase of each sinusoid to a specific angle with quadratic phase to form a low peak-to-average power ratio (PAPR) preamble with about a PAPR value of 2.6 decibels (dB). A channel estimate circuit is operative for measuring fluctuations within a flat-top spectrum of the received OFDM communications signal corresponding to the preamble to reflect the frequency response of the communications channel.

Methods and apparatus are described for time synchronizing a receiver to orthogonal frequency division multiplexing (OFDM) signals in a multiple-input/multiple-output (MIMO) system, the signals being transmitted from multiple transmitters and received at multiple receivers. The method includes determining the frequency offset and the sampling clock offset of the received signals.

A method and apparatus of transmitting a reference signal in a wireless communication system is provided. Demodulation Reference Signals (DMRSs) for a plurality of respective antennas is generated. The DMRSs are mapped to a resource region, and transmitted through the respective corresponding antennas. The DMRSs are multiplexed using at least one of frequency division multiplexing (FDM), code division multiplexing (CDM), and time division multiplexing (TDM) methods and mapped in the resource region. Also, a position of an orthogonal frequency division multiplexing (OFDM) symbol to which the DMRSs are mapped in the resource region is an OFDM symbol to which a physical downlink control channel (PDCCH) and a legacy cell-specific reference signal (CRS) are not mapped.

A method of transmitting feedback information in a wireless communication system is disclosed. More specifically, the method comprises a mobile station (MS) which determines whether to transmit feedback information to a base station (BS) without solicitation from the BS. After determining to do so, the MS transmits a request message to request the BS to allocate an uplink resource for transmitting at least one unsolicited header and thereafter receives the uplink resource allocation from the BS. Lastly, the MS transmits the at least one unsolicited header via the allocated uplink resource.

A framing method of fixing a training signal and a control channel for multi-link (direct link and relay link) synchronization in a multi-hop relay cellular network, and a transmitting/receiving apparatus for supporting the framing method. A base station (BS) transmits BS downlink (DL) subframe sequentially including a preamble, control information, and a DL burst to a relay station (RS) or a first mobile station (MS) connected to the BS by direct link. The RS transmits an RS DL subframe sequentially including a DL burst, a postamble, and control information to a second MS connected to the BS by relay link. Therefore, difficulties of initial synchronization, handoff, and cell search can be removed from MSs. Furthermore, multi-link bursts can be located between the preamble and the postamble by Time Division Multiplexing (TDM) or Frequency Division Multiplexing (FDM).

A fiber optic network transmits data between a hub node and a plurality of local nodes connected by at least one unidirectional fiber ring. Downstream data streams are carried on wavelength-division-multiplexed optical carriers from the hub node to the local nodes. An optical carrier corresponding to a specific wavelength carries downstream data streams to a specific local node. Downstream data streams are multiplexed onto an optical carrier via orthogonal frequency division multiplexing. A parallel signal detector in each local node detects all downstream optical carriers. A signal processing module demultiplexes the data stream from the optical carrier having the specific wavelength corresponding to the local node. An upstream data stream is multiplexed via orthogonal frequency division multiplexing onto an upstream optical carrier having the same specific wavelength and transmitted from the local node to the hub node. Upstream data awaiting transmission is allocated to specific subcarriers and time slots.

A method of determining random access resources performed by a mobile terminal, the method comprising: receiving information on available random access resources from a network; deciding how to derive the random access resources to be allowed based on default values or information received from the network; measuring received signal quality of at least one of a cell to be accessed and a neighboring cell; and deriving the allowed random access resources based on the deciding and the measuring.

A method and apparatus for determining a control resource set for system information in a wireless communication system is provided. A user equipment (UE) receives a configuration of control resource set (CORESET) for remaining system information (RMSI) via a synchronization signal (SS) block from a network, and determines the control resource set for the RMSI according to the configuration. The SS block may include a physical broadcast channel (PBCH). A time and frequency location of a common search space (CSS) for the RMSI may be aligned with the SS block by at least one of time division multiplexing (TDM) or frequency division multiplexing (FDM).

A base station having the strongest downlink signal is identified by utilizing a unique slope of a pilot tone hopping sequence being transmitted by a base station. Specifically, base station identification is realized by determining the slope of the strongest received pilot signal, i.e., the received pilot signal having the maximum energy. In an embodiment of the invention, the pilot tone hopping sequence is based on a Latin Squares sequence. With a Latin Squares based pilot tone hopping sequence, all a mobile user unit needs is to locate the frequency of the pilot tones at one time because the pilot tone locations at subsequent times can be determined from the slope of the Latin Squares pilot tone hopping sequence. The slope and initial frequency shift of the pilot tone hopping sequence with the strongest received power is determined by employing a unique maximum energy detector. In one embodiment, the slope and initial frequency shift of the pilot signal having the strongest received power is determined by finding the slope and initial frequency shift of a predicted set of pilot tone locations having the maximum received energy. In another embodiment, the frequency shift of the pilot signal with the strongest, i.e., maximum, received power is estimated at each of times “t”. These frequency shifts are employed in accordance with a prescribed relationship to determine the unknown slope and the initial frequency shift of the pilot signal.

PCT No. PCT/EP96/02209 Sec. 371 Date Nov. 17, 1997 Sec. 102(e) Date Nov. 17, 1997 PCT Filed May 23, 1996 PCT Pub. No. WO96/41458 PCT Pub. Date Dec. 19, 1996In the case of the OFDM method, a large number of modulated carriers are transmitted using frequency division multiplexing, a spectrum having a virtually rectangular shape being produced as a result of the large number of carriers. In order to separate the carriers from one another again in the receiver, a Fast-Fourier-Transformation is carried out, it then being possible to separate each carrier cleanly from the others provided the carriers are exactly orthogonal with respect to one another. The carrier orthogonality can, however, be disturbed by various causes. Furthermore, the wanted signal must be separated from the undesired adjacent channel signals by analog or digital filtering in the receiver. In order to improve carrier and channel separation, the selectivity of the FFT filtering can be increased by enlarging the number of FFT components. However, this normally leads to an undesirably sharp increase in the computation complexity. The refinement according to the invention of the time window which is used for the FFT and the oversampling before the FFT make it possible, however, to dispense with calculation of some of the coefficients.

The invention discloses a multi-wavelength high-sensitivity online monitor of multi-component NH3 and H2O based on semiconductor laser absorption spectroscopy. It contains host chassis and open long-path system. Equip power receptacle, switch, fiber connector and data transmission interface. It is characterized in that: there are near-infrared semiconductor laser, semiconductor laser controller, phase-locked amplifier, signal generator, data collecting and controlling module and infrared detector in host chassis which is connected with field optical system by fiber. Open optical system contains send-receive optical telescope and multielement reflector array. Optical telescope has input and output fiber couplers. The device realizes simultaneous testing of gas multi-component by using multi-wavelength and frequency division multi-signal detecting technique.

Provided is a data transmission apparatus to transmit a reference orthogonal frequency division multiplexing (OFDM) symbol generated by frequency division multiplexing a reference symbol and a data symbol, and a data reception apparatus to estimate a channel using the reference OFDM symbol. Since the reference symbol and the data symbol are frequency division multiplexed, a Peak to Average Power Ratio (PAPR) may not increase greatly, and the transmission apparatus may transmit the reference OFDM symbol to the data reception apparatus more frequently. Accordingly, the data reception apparatus may estimate a channel accurately.

There is provided a system and method for sharing a wireless spectrum compromising a first transceiver for establishing the communication channels within the allocated bandwidth using a first protocol, a broker for determining the unused bandwidth within the allocated bandwidth, and a second transceiver for establishing the further communication channels within the unused allocated bandwidth using a second protocol. The first protocol is UMTS and the second protocol is WiMax. The broker may monitor UMTS traffic and allocate bandwidth to WiMax traffic whenever resources are idle or traffic are low or allocate bandwidth in dependence upon time division multiplexing, or frequency division multiplexing or may overlap a WiMax signal with a UMTS signal.

The present invention provides a method executed by a base station. The method comprises: (S320) generating a code word sequence comprising system information of the base station; (S330) modulating the code word sequence, and generating a physical broadcast channel (PBCH) sequence; (S340) selecting a physical resource block (PRB) for each PBCH in the PBCH sequence; and (S350) executing the mapping between the PBCH and a resource element (RE) in the selected PRB. The PRB has a distributed PRB frequency division multiplexing format or an integrated PRB frequency division multiplexing format. The present invention further provides a method executed by a user equipment and a corresponding base station and a user equipment. By using the present invention, the energy utilization rate can be enhanced and the frequency spectrum efficiency in an LTE-Advanced system can be improved, and time/frequency resource conflicts between cells can be reduced.

A wireless communication system includes an intermediate node, a first node and a second node. There is described a method for implementing MIMO based network coding, comprising the first node transmitting first data to the intermediate node, and the second node transmitting second data to the intermediate node. Both the first node and the second node may use spatial multiplexing or time division multiplexing or frequency division multiplexing on a common/different resource. The intermediate node receives the transmissions from the first node and second node, and performs network coding on the first data and second data using a predefined network coding scheme to produce network coded information. The intermediate node transmits the network coded information to the first node and second node using multi-user MIMO; and; each first or second node receives the MIMO transmissions from the intermediate node and applies network decoding procedures to recover the first data and second data. Network coding schemes include Decode and Forward (DF), Map and Forward (MF) and Amplify and Forward (AF). The first node and second node may be members of groups of nodes all within the same coverage area. A method for scheduling MIMO-based network coded transmissions is also described. Hybrid Automatic Repeat Request (HARQ) transmission may also be network encoded.

The invention relates to a thermoplastic polyurethane modified composite material for FDM (frequency division multiplexing) 3D printing and a preparation method thereof. The composite material is prepared from the following components in parts by weight: 70-95 parts of thermoplastic polyurethane, 1-5 parts of antioxidant, 1-5 parts of hydrolysis-resistant stabilizer, 1-5 parts of compatilizer, 1-5 parts of lubricant and 1-10 parts of other assistant. Compared with the prior art, the antioxidant, hydrolysis-resistant stabilizer, lubricant and other assistants are added, so that the modified composite material has the advantages of favorable mechanical properties, high elasticity, favorable wear resistance, higher heat stability, hydrolysis resistance, higher oxidation resistance and higher processability. When being used for FDM 3D printing, the thermoplastic polyurethane modified composite material has the characteristics of smooth printing process, no odor, smooth printing product surface, beautiful appearance, stable size, low tendency to shrinkage, favorable mechanical properties, high flexibility, high heat stability, high hydrolysis resistance, high oxidation resistance and high processability.