72 results about "Frequency domain multiplexing" patented technology

A method and apparatus for wireless communication are described. In one embodiment, a method for communicating with a subscriber comprises transmitting orthogonal frequency domain multiplexing (OFDM) signals to the subscriber, and receiving direct-sequence spread spectrum (DSSS) signals from the subscriber.

An external mask-based radiance camera may be based on an external, non-refractive mask located in front of the main camera lens. The mask modulates, but does not refract, light. The camera multiplexes radiance in the frequency domain by optically mixing different spatial and angular frequency components of light. The mask may, for example, be a mesh of opaque linear elements, which collectively form a grid, an opaque medium with transparent openings, such as circles, or a pinhole mask. Other types of masks may be used. Light may be modulated by the mask and received at the main lens of a camera. The main lens may be focused on a plane between the mask and the main lens. The received light is refracted by the main lens onto a photosensor of the camera. The photosensor may capture the received light to generate a radiance image of the scene.

An acquisition and tracking apparatus is provided for tracking digitized spread spectrum navigation signals modulated with a spreading code according to any of a set of modulation types including Binary Phase Shift Keying (BPSK) with and without Frequency Domain Multiplexing Access (FDMA), time multiplexed BPSK, Quadrature Phase Shift Keying (QPSK), sine and cosine Binary Offset Carrier (BOC), modified, complex, and time multiplexed BOC (TMBOC), the apparatus comprising a plurality of universal tracking channels, each coupled to an interrupt module. The universal tracking channel includes a carrier demodulation module, a code generation module, a correlator module, a code frequencies generation module, and a subcarrier combining module for efficiently using the correlator resources in the correlation of the data and the pilot components of the signal within a single universal tracking channel. A corresponding method of operation is also provided.

The invention provides a vehicle to everything (V2X) business transmission method and device, and a resource allocation method and device. The V2X business transmission method includes that a first onboard unit OBU acquires the transmission resources for transmitting the V2X business, the transmission resources include the resources required to send the V2X business data and scheduling information in the V2X business, the scheduling information refers to the information indicating the resource scheduling of the V2X business data, the first OBU transmits the scheduling information and the V2X service data to the second OBU on the transmission resources, the scheduling information and the V2X business data are subjected to frequency domain multiplexing in the same subframe in the transmission resources and the scheduling information indicates that the V2X business data is subjected to resource allocation in the same and/or different subframes. According to the invention, the problem that the D2D technology in the prior art can only send the resource scheduling information and V2X business data separately is solved, and the gaps in the relevant technology are filled.

The invention discloses a method and device for transmitting a channel state information reference signal (CSI-RS). The method for transmitting the CSI-RS comprises the following steps of: determining the port quantities and the frequency domain displacement of CSI-RS patterns of user equipment, wherein the CSI-RS patterns refer to CSI-RS four-port patterns and a CSI-RS eight-port pattern, the CSI-RS four-port patterns are same and are separated orthogonally in a frequency domain multiplexing mode according to different frequency domain displacements, and the CSI-RS eight-port pattern is formed by combining the CSI-RS four-port patterns of any two adjacent cells; and informing the user equipment of the port quantities and the frequency domain displacement of the CSI-RS patterns to make the user equipment perform downlink channel estimation according to the port quantities and the frequency domain displacement of the CSI-RS patterns. Due to the adoption of the method and the device, the transmission of the CSI-RS can be realized.

The invention discloses a method for estimating pulse noise in an OFDM (Orthogonal Frequency Domain Multiplexing) underwater acoustic communication system. At a receiving end, sparse estimation is performed on pulse noise on an OFDM signal in an underwater acoustic channel transmission process according to a frequency domain signal subjected to redundant Doppler frequency shift compensation, and frequency offset compensation is performed on the frequency domain signal subjected to the redundant Doppler frequency shift compensation with void subcarriers. Under the consideration of mutual interference between the pulse noise and a carrier frequency offset in underwater acoustic communication, compensation of the carrier frequency offset is added in an iteration process while the pulse noise is estimated with all subcarriers and a posteriori distribution under a framework of conventional sparse Bayesian learning, and the frequency domain signal subjected to the redundant Doppler frequency shift compensation and a measurement diagonal matrix for estimating the pulse noise are updated continuously in order to lower influences between the two types of interference. Moreover, the pulse noise is estimated by full utilization of all the subcarriers in the method, so that the spectrum efficiency and the performance of the communication system are improved.

An OFDM communication system employs a cell time division time frame for a plurality of overlapping cells wherein the time frame comprises time slots with each time slot allocated to one of the overlapping cells and each time slot being either an information exchange time slot or a data time slot. Remote nodes (101-105) transmit resource requests for at least one subcarrier in a data time slot to one or more of the central nodes (107, 109) in the information exchange time slots of those nodes (107, 109). The central nodes (107, 109) broadcast information of uplink channel characteristics received in the request messages and the remote nodes (101-105) use this to determine whether to abandon or continue the resource request. Eventually, the remote node may decide to use the resource and thus to transmit in the associated data time slot. A distributed multi-cell resource allocation can be achieved based on distributed decisions in the remote stations.

A method is provided for applying frequency domain multiplexing of unicast and multicast services on a single carrier, such that both services can operate at the same time, and may be received with the same RF front end and A/D converter. In order to reduce subcarrier interference between unicast and multicast tones a guardband is introduced between the unicast and multicast bands, where the guardband can be fixed or variable within a sub-frame. Also disclosed is a device and computer program product operable with the device.

A dual band high isolation antenna structure includes a diplexer unit, a 4-port decoupling module, a first frequency band antenna assembly, and a second frequency band antenna assembly. The diplexer unit is operable to frequency domain multiplex between a first frequency band and a second frequency band. The 4-port decoupling module is operably coupled to the diplexer unit and is operable to isolate a first pair of ports from a second pair of ports. The first frequency band antenna assembly is operably coupled to the diplexer unit and is operable to transceive wireless signals in the first frequency band. The second frequency band antenna assembly is operably coupled to a port in each of the first and second pairs of ports and is operable to transceive wireless signals in the second frequency band.

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.

There is proposed a mechanism for controlling and conducting a discovery procedure of small cells or secondary cells located in a macro cell or primary cell. The discovery procedure is based on a discovery signal communicated via PDCH and based on a positioning reference signal (PRS). For configuring the signaling of the discovery signal, frequency domain multiplexing for splitting resources of the PRS in the frequency domain for increasing capacity, and/or usage of reserved communication resources for the signaling of the discovery signal are employed. Assistance information is provided to the UE for supporting the discovery of small cells.

A COFDM demodulator providing independent DQPSK symbol amplitude and phase equalization provides improved soft-symbol estimates by reducing the possibility of clipping in the differential demodulator, improving the tolerance of the differential demodulator to finite word length effects, correcting for phase drifting between adjacent subcarriers, and improving signal-to-noise ratio (SNR) calculation accuracy for maximal ratio combining applications. Separate acquisition and tracking modes for the amplitude and phase equalizers are provided that handle start-up, reacquisition, and steady-state operation of the demodulator.

A very narrow band multipoint communication system suitable for use in an automatic meter reading (AMR) system having a communication protocol that divides each main channel of a frequency or digital code hopping system into multiple sub-channels and applies frequency division multiplexing among the sub-channels. Each sub-channel exhibits a very narrow band characteristic that allows gain increase to increases the transmission range of the meters. In addition, frequency division multiplexing among the sub-channels greatly increases the number of meters that can communicate on each main channel. The data collection device demodulates and decodes the multiplexed meter signals at an intermediate frequency with electronic circuitry. The resulting very narrow band AMR system exhibits greater transmission range, greater bandwidth and can accommodate a much larger number of meters per data collection device in comparison to conventional narrow band AMR system.

A coils array (40, 40') including a plurality of coils (71, 72, 73) receives magnetic resonance signals from an examination region of a magnetic resonance imaging scanner (10). Each coil has mixing circuitry (74, 75, 76, 80, 81, 82) that frequency-shifts the received magnetic resonance signal to a selected transmission channel frequency. The coils array further includes combining circuitry (90) that combines the frequency-shifted magnetic resonance signals to produce an analog frequency domain multiplexed transmission signal output of the coils array. Receiver electronics (56, 56'') receive the analog frequency domain multiplexed transmission signal from the coils array. The receiver electronics include an analog-to-digital converter (164) that digitizes the analog frequency domain multiplexed transmission signal and digital signal processing circuitry (166) that processes the digital frequency domain multiplexed transmission signal to recover digitized signals corresponding to the magnetic resonance signals received by the plurality of coils.

The application discloses a signal sending and carrier detection method. The method comprises the following steps: a signal sending way at a communication node is different from a sending way out of a time window in a predefined time window, and the method comprises a carrier detection way and/or data transmission way. By applying the application disclosed by the invention, a frequency domain reuse factor among the nodes in the same access technology can be improved, and meanwhile, the coexistence of other access technology can be guaranteed.

The invention discloses a frequency domain multiplexing method for hopping frequency users and non-hopping frequency users, which comprises the following steps of: dividing at least one frequency domain serving as a non-hopping frequency area and at least two frequency domain serving as hopping frequency areas in the bandwidth of a physical uplink shared channel of an LTE system; separating the hopping frequency areas and the non-hopping frequency area on the frequency domains, and separating the different hopping frequency areas or the different non-hopping frequency areas on the frequency domains; and configuring the non-hopping frequency users in the non-hopping frequency area, and configuring the hopping frequency users in the hopping frequency areas, wherein each hopping frequency of the hopping frequency users hops between the different hopping frequency areas. The invention also discloses a frequency domain multiplexing device for the hopping frequency users and the non-hopping frequency users.

An apparatus, system, and method of performing adaptive frequency domain equalization in an Orthogonal Frequency Domain Multiplexing (OFDM) based communication system transmitting data information, wherein the method comprises receiving OFDM symbols comprising scattered pilots; obtaining channel estimates on every third bin of the scattered pilots in a frequency domain, wherein the channel estimates are obtained by performing an interpolation in a time domain across the received OFDM symbols; estimating an original channel based on the channel estimates, wherein the original channel in the time domain is estimated by applying a finite impulse response (FIR) low-pass filter in a frequency domain, wherein the FIR low-pass filter is adaptive according to a delay span of an original channel impulse response and is sufficiently wide to cover the delay span of the original channel impulse response; and dividing the received OFDM symbols by the channel estimate to obtain transmitted data information.

A network sends data blocks in a first/n1h radio frame having a first configuration of uplink to downlink transmission time intervals TTIs. Each of these data blocks originate a separate hybrid automatic repeat request HARQ process. The network then frequency or spatially mutliplexes first re-transmissions of at least two of the data blocks in at least one TTI of a sequentially next second/(n+l)st radio frame having a different second configuration of uplink to downlink TTIs. If necessary second re-transmissions of the HARQ processes can also be similarly multiplexed in a TTI of a third/(n+2)nd radio frame sequentially next after the second/(n+l)st frame. In the examples, if frequency domain multiplexing the frequency mutliplexed first re-transmissions are separately scheduled; or if spatial domain multiplexing the spatially mutliplexed first re-transmissions are scheduled with a single physical downlink control channel PDCCH.

A frequency domain multiplexed signal receiving method which decodes received signals that are multiplexed in a frequency domain, includes: a digital signal acquisition step of acquiring digital signals from the received signals that are multiplexed in the frequency domain; an offset discrete Fourier transform step of applying an offset discrete Fourier transform to odd discrete point numbers based on the acquired digital signals; and a decode step of decoding frequency domain digital signals in the frequency domain obtained by the offset discrete Fourier transform, and that are the frequency domain digital signals of one or more frequency channels.

The invention provides a method and device for downlink transmission. According to an embodiment, the method is based on time domain multiplexing. According to the method, a physical resource block (PRB) pair used for transmitting scheduling information of one set of user equipment is selected from predetermined PRB pairs capable of being used for transmitting the scheduling information in available PRB pairs, and the scheduling information is transmitted to the user equipment on predetermined subcarriers of first two orthogonal frequency division multiplexing symbols of the selected PRB pair. In addition, the invention further provides a technical scheme based on frequency domain multiplexing. According to the embodiment, the technical scheme based on time domain multiplexing and frequency domain multiplexing is provided, so PMCH information transmission on new types of carriers can be achieved in LTE-A, and meanwhile the influence on regulations of an RAN1 is limited.

The invention discloses a communication method, a system, a signal multiplexing method and a device between time and frequency domains. A method for optical fiber communication between frequency domains comprises the following steps: at a transmitting end, an inputted serial binary electrical signal is converted into an N-channel parallel electrical signal, and the N-channel parallel electrical signal is converted into a multiplex electrical signal between time domains; the multiplexed electrical signal in frequency domain is modulated on optical carrier to form multiplexed optical signal, which is input to optical fiber link for transmission; at a receiving end, the multiplexed optical signal received from the optical fiber link is converted into a multiplexed electrical signal, and the multiplexed electrical signal is demultiplexed to restore the multiplexed electrical signal to a serial binary electrical signal. The invention extends the traditional frequency domain multiplexing technology to time. Multiplexing and demultiplexing are realized in the frequency domain between the time and frequency, which suppresses the signal degradation caused by the nonlinear and dispersion effects of optical transmission in optical fiber, improves the frequency band efficiency in OFDM system and reduces the PAPR.

The invention discloses a frequency-domain synchronous signal transmission and detection method of an orthogonal frequency division multiplexing system, wherein the transmission method obtains data by IFFT (inverse fast discrete Fourier transform) operation on a PN sequence (pseudo-random sequence) The time-domain preamble training sequence of the frame; wherein the detection method utilizes a time window with the same length as the preamble training sequence to slide the received time-domain data stream, and sends the data in the window into the FFT (Fast Discrete Fourier Transform) operation After the module, use the PN sequence correlation characteristics in the frequency domain to determine whether there is a signal arriving, and obtain the precise time domain synchronization position of the signal. The frequency-domain synchronous signal transmission and detection method of the OFDM system avoids the influence of time-domain interference, and at the same time utilizes the correlation characteristics of the PN sequence in the frequency domain. In a synchronous manner, the detection accuracy of the frequency domain correlation method provided by the present invention is greatly improved. The present invention can also realize reliable signal detection and synchronization under harsh channel conditions with interference.