187 results about "High spectral efficiency" patented technology

An uplink and downlink channel structure supports a shared downlink data channel. The new structure accommodates advanced physical and Medium Access Control (MAC) layer techniques, such as incremental redundancy (IR), fast adaptation to channel conditions, and multiple input multiple output (MIMO) antenna configuration. The proposed changes are intended to lead to a downlink structure that achieves higher spectral efficiency for the packet oriented services over then shared downlink channel. Additionally, the new structure uses the base station transmit power information and of the channelization (OVSF) code space more efficiently.

Methods and apparatus are provided for command and control of an unmanned vehicle (“UV”). A preferred embodiment of the invention includes a Virtual Pilot (“VP”), which includes a Brain and an Arena The Brain includes rules governing the behavior of the UV and information on missions to be performed. The Arena includes state information about the UV and its environment. UVs in a swarm communicate with each other, as well as with various ground stations, through regular updates. Backup schemes are provided to deal with the failure of a UV module, thereby providing partial degradations in performance. Communication among the UVs and ground stations of a system employ a probabilistic scheme that promotes high spectral efficiency.

Digital compensation of chromatic dispersion (CD) effect experienced by optical orthogonal frequency-division multiplexed (OFDM) signal in fiber transmission is provided in the frequency domain using a Fast Fourier Transform / Inverse Fast Fourier Transform (FFT / IFFT) pair with equal length of digital samples prior to OFDM receiver signal processing, wherein the equal length is larger than the length of a FFT used for OFDM subcarrier demultiplexing of the received signal. The OFDM signal processing is independent of fiber CD, so small guard-interval (GI) can still be used to achieve high spectral efficiency even under the experience of large CD. The GI need only to be large enough to accommodate other effects such as polarization-mode dispersion. The length of an IFFT used for OFDM subcarrier multiplexing, as well as the FFT for OFDM demultiplexing can be sufficiently small so subcarrier spacing is sufficiently large to tolerate typical frequency offsets between the transmitter laser and the optical local oscillator.

Systems and methods of wireless communication in which wireless devices are adapted to implement adaptive waveform selection are disclosed. For example, operation according to embodiments may provide for use of a waveform design that minimizes peak-to-average power ratio (PAPR), such as single-carrier frequency division multiplexing (SC-FDM), as well as a waveform design that provides higher spectral efficiency, such as orthogonal frequency division multiplexing (OFDM), for scenarios that are not power-limited and the higher PAPR is acceptable. Adaptive waveform selection may be based implicitly on one or more parameters or may be based on explicit signaling. Adaptive waveform selection may be utilized with respect to initially establishing a communication link and / or with respect to an established communication link.

The present invention discloses a wavelength-division multiplexing passive optical network (WDM-PON) capable of high-bandwidth transmission for optical signals by using modulation format having high spectral efficiency. The WDM-PON according to the present invention provides a larger capacity and higher bandwidth transmission economically (at lower costs) by using a modulation format where spectral efficiency (a transmission bit number per a unit band width) is high, while using a low noise part of a light source.

The invention discloses a hybrid precoding method of a large-scale MIMO system applied to a millimeter wave band. The method comprises the following steps: S1: obtaining, by a base station, channel state information (CSI); S2: performing SVD on a downlink channel to obtain a right singular matrix V, using a phase angle of a former NRF column of the V as each element in an analog precoding matrix FRF, wherein NRF represents the number of radio frequency links; S3: using former Ns columns of the right singular matrix V subjected to the SVD on the downlink channel as an optimal precoding matrix Fopt, and obtaining a digital precoder (the formula is described in the specification) according to the Fopt and the FRF by using a least-squares solution (LS), wherein Ns represents the number of datastreams; and S4: performing first time precoding on the data streams through the FBB obtained in the step S3, then performing phase adjustment on a signal, namely, the FRF in the step S2, by using aphase shifter, and finally transmitting the signal through an antenna. Compared with the prior art, the hybrid precoding method disclosed by the invention has the advantages that no optimization method or complicated iterative algorithm is needed, so that the complexity is greatly reduced, and higher spectral efficiency can be achieved.

Invention presented here relates to Low Probability of Exploitation and Anti Jamming communication system offering high spectral efficiency. The object of the present invention is achieved by hopping in polarization domain and by employing an adaptive polarization-nulling algorithm (FIG. 18, H [2,2]) to detect and eliminate jamming signal. The use of signals which hops or spreads in polarization domain does not need wide frequency spectrum due to which, the said modulation when employed at the physical layer offers and extremely secure and survivable wireless communication at very high data rates.

The invention belongs to the technical field of wireless communication and discloses a standard-orthogonalization-based hybrid pre-coding method for a large-scale MIMO system. Analog pre-coding design is based on equal-gain transmission. The phase of a main diagonal element of a baseband equivalent channel matrix is set to zero to obtain the maximum antenna array gain so as to reduce the total energy consumption and complexity of a transmitter. The design of a digital pre-coding matrix is based on standard orthogonalization and singular value decomposition. By mapping a desired user to other user null space, the interference between users is completely eliminated and the maximum spectral efficiency is obtained. A numerical result shows that the performance of the hybrid pre-coding method, when equipped with a small number of radiofrequency links, approaches that of an all-digital pre-coding solution that requires the same number of radiofrequency links as the antennas, and can obtain high spectral efficiency with low implementation complexity.

The invention discloses an OFDM (Orthogonal Frequency Division Multiplexing) underwater acoustic communication method with high spectral efficiency under a time-varying double-spread channel condition, and belongs to the technical field of underwater acoustic communication. The method comprises the following steps: carrying out band-pass filtering on a received signal r (k), carrying out front-endprocessing such as ADC (Analog to Digital Converter) conversion into a digital signal, carrying out down-conversion and low-pass filtering, estimating average Doppler by utilizing a fuzzy function method, carrying out resampling and frequency correction, multiplexing the signal, carrying out time domain equalization and frequency domain equalization, carrying out diversity combination, and then adopting the OMP-DCD algorithm to perform residual Doppler compensation. an iterative signal processing technology is adopted, an LDPC decoder and an equalizer are cascaded through soft-in soft-out mapping / demapping and an interleaver / deinterleaver, close information interaction is achieved in the two modules, soft information transmitted in a reciprocating mode is fully utilized, and interferenceof a time-varying double-spread channel is effectively resisted. According to the method, the complexity and the performance can be well compromised, and serious inter-symbol interference, inter-carrier interference and pilot frequency-pilot frequency interference in the transmission process are efficiently solved. And the method is low in complexity and can be realized on the DSP in real time.

The present invention discloses a high performance optical architecture for multiplexing and demultiplexing channels for use in high spectral efficiency optical systems. In general, the MUX and DeMUX architectures of the present invention will fall into two key sections or stages: a wavelength group section and a channel section. The group section makes use of characteristic associated with groups of multiplexed channels for separating said groups from an optical signal having a plurality of multiplexed groups. Advantageously, in preferred embodiments, the channel section is colorless (non-wavelength specific between groups) in order to reduce cost and complexity. With respect to the colorless channel section, components with free spectral ranges (FSRs) have been strategically added to provide repetitive optical filtering functions on group of channels (i.e., subsets of channels within each band of wavelengths) so that the colorless channel section can operate in any respective group identically. Hence each of said colorless channel sections are interchangeable. Advantageously Distortion compensation can be performed on a per group basis.

The invention discloses an adaptive switching method of an SU-MIMO mode and an MU-MIMO mode and an adaptive switching apparatus thereof. Estimation is carried out on a current signal environment to calculate SINRs of an SU-MIMO mode and an MU-MIMO mode; according to the SINRs, table looking up is carried out to obtain matched modulation modes and error rates; and then, spectral efficiencies of the two modes are calculated and then are compared as well as the mode with the high spectral efficiency is used as an optimal mode in a channel environment. In addition, a tolerance mechanism is added in the switching process so as to avoid a ping-pong effect. According to the invention, characteristics of stable performance, a few response time and low system load can be realized.

The invention discloses a rotated electromagnetic wave orbital angular momentum wireless transmission system. Different orbital angular momentum state data of transmitting end electromagnetic waves are converted into different frequency offset of receiving end electromagnetic waves through rotating a spiral phase plate, so that orthogonal frequency division multiplexing signals can be formed at a receiving end; and the receiving of orbital angular momentum electromagnetic waves is converted to time-domain orthogonal receiving from space-domain receiving, so that the problem of free spatial divergence caused by an orbital angular momentum electromagnetic wave beam angle in the prior art can be solved, and long-distance, large-capacity and high-spectral efficiency transmission of electromagnetic wave orbital angular momentums can be realized. According to the rotated electromagnetic wave orbital angular momentum wireless transmission system of the invention, baseband signals are modulated and are up-converted to radio-frequency signals, and the radio-frequency signals are fed into a transmitting antenna; after being converged by a lens, the radio-frequency signals are emitted to the spiral phase plate, so that orbital angular momentum electromagnetic waves can be generated; the spiral phase plate rotates under the control of a rotation device, so that rotated orbital angular momentum electromagnetic waves can be generated; after receiving a part of electromagnetic waves, the receiving end carries out down-conversion on the electromagnetic waves and transmits the converted electromagnetic waves to a demodulator; and the electromagnetic waves are demodulated through adopting an orthogonal frequency division multiplexing signal demodulation method.

Apparatus and methods are provided for receiving differential phase-shift keyed (DPSK) optical signals subjected to tight optical filtering, such as may be experienced by 40 Gb / s and 100 Gb / s channels in a dense wavelength division multiplexing (DWDM) communications system with 50 GHz channel spacing. An optical DPSK receiver is described which employs an optical delay interferometer (ODI) demodulator having a free spectral range (FSR) that is larger than the symbol rate (SR) of the DPSK signal to be demodulated. The receiver includes means for introducing an additional power imbalance between the outputs of the ODI demodulator, and the additional power imbalance may be related to the ratio of FSR to SR. The additional power imbalance increases the signal tolerance to tight optical filtering, thereby achieving high spectral efficiency in applications such as DWDM.

The invention belongs to the technical field of optical fiber communication, in particular to a multimode blind equalization digital signal processing algorithm applied to a quadrature duobinary (QDB) frequency-spectrum-compressed polarization multiplexing signal. According to the invention, in a coherent optical communication system, the multimode-blind-equalization-based digital signal processing algorithm is adopted to realize equalization compensation and demodulation of an optical signal which is subjected to QDB frequency spectrum compression; suitable filters are adopted in an electric field or an optical field to realize the QDB frequency spectrum compression of a polarization multiplexing signal; the polarization demultiplexing of a transmitted optical signal is realized by using a cascade multimode algorithm (CMMA); frequency offset estimation is realized by using a multimode quadrature phase shift keying (QPSK) partition method; and phase retrieval is realized by using the multimode QPSK partition method and maximum likelihood estimation. By the algorithm, the frequency spectrum efficiency of the signal can be effectively improved, the transmission quality of the signal can be improved, and high-spectral-efficiency coherent optical transmission can be realized.

The invention discloses a high-spectral-efficiency pilot design and channel estimation method in an FBMC system. According to the method, at a transmitting end of the FBMC system, a column of data power on a frequency time coordinate is halved when a pilot is inserted into a head of each data block, data is symmetrically placed at two sides of the pilots, and the pilots are still repeated continuously according to a rule of [1, -j, -1, j ]<T>; at a system receiving end, the channel estimation accuracy is effectively improved through an iteration method, it is assembled that data protection columns are placed at two sides of the pilots, pseudo-pilots are calculated for channel estimation, the data placed at two sides of the pilots are demodulated; and the pseudo-pilots are calculated again for channel estimation through utilization of the demodulated data at two sides of the pilots, and all data is demodulated. According to the method, the pilot cost is effectively reduced in the FBMC system, and the spectral efficiency is improved.

Optical packets are generated by generating a first optical beam with a first wavelength and a second optical beam with a second optical beam. The first optical beam is modulated with a payload signal and then filtered to reduce the bandwidth of the signal. The second optical beam is modulated with a label signal. The filtered modulated first optical beam and modulated second optical beam are combined to generate a dual-wavelength optical beam.

The invention belongs to the field of digital wireless communication, and discloses a new spatial modulation (SM) transmission method, namely, spatial modulation (TRSM) based on selection of receiving and transmitting antennas. The method comprises the following steps: at a transmitting end, firstly dividing code word bits into two parts, mapping a part of code word bits into modulation constellation symbols through amplitude phase modulation (AMP), mapping the other part of code word bits into index numbers of the receiving and transmitting antennas through a spatial modulator, and then designing a to-be-sent spatial modulation signal vector according to the index numbers of the receiving and transmitting antennas. The spatial modulation method disclosed by the invention integrates spatial modulation (TSM) of transmitting antenna selection and the spatial modulation (RSM) of receiving antenna selection, thereby not only carrying information through the index numbers of the transmitting antenna, but also carrying information through the index number of the receiving antennas. Compared with the traditional TSM and RSM methods, the provided TRSM method has higher spectral efficiency and relatively low error beds. In addition, at a receiving end, in order to reduce the decoding complexity, the invention further provides a corresponding suboptimal soft detection algorithm.

The invention discloses a bandwidth compressed high-spectral-efficiency multi-carrier communication method, belonging to the field of multi-carrier communication technology. The method comprises the following steps: serially connecting external coding and multi-carrier modulation processing at a transmitter through pseudo-random interleaving, and equalizing to a mode of encoding signals through aserially concatenated Turbo code; performing decoding and interference cancellation at a receiver by using an iterative decoding structure of a serial Turbo code, serially connecting internal decodingprocessing and external decoding processing through pseudo-random interleaving and de-interleaving, and continuously exchanging soft information with each other to achieve iteration, wherein the internal decoding mode performs iterative estimation and cancellation for ICI by using a successive interference cancellation method, the external decoding mode decodes external codes by using a soft input and soft output method, and thus the impact of Gaussian white noises of channels can be resisted. Compared with existing methods, by adopting the method disclosed by the invention, a better detection performance can be obtained by using a lower computation complexity, and meanwhile, a large multi-carrier communication system with more sub-carriers can be adapted.

The invention discloses a polarity diversity reception method based on an SOQPSK-TG signal. The method comprises the following steps: adopting two ADCs to transfer a received levogyration polarity signal and a received dextrorotation polarity signal into digital signals respectively; adopting an automatic gain control loop to enable the two digital signals to be constant in amplitude or in a threshold value section; tracking frequency difference and phase difference of the two gained digital signals through a difference module loop to fulfill same frequency and phase locking of the two digital signals; adopting maximal-ratio combining to obtain average SNR gain; tracking Doppler frequency shift to conduct carrier recovery; conducting position timing clock recovery; tracking clock phase shift and frequency shift between a receiver and a transmitter. The invention further discloses an SOQPSK-TG signal modulation and polarity diversity reception device based on FPGA. The modulation and reception device utilizes the characteristics of constant envelope and high spectral efficiency of the SOQPSK-TG to meet modern satellite communication demand; the polarity diversity reception technology is introduced to avoid deep zero point influence; system performance is improved.

The invention discloses an orbital angular momentum (OAM) multiplexing transmission system based on phase surface relaying. The OAM multiplexing transmission system comprises a signal transmitting end, a signal receiving end and a central receiver, wherein the signal transmitting end is used for collecting user data, modulating the user data into OAM electromagnetic waves of a plurality of modes,and transmitting the OAM electromagnetic waves to the signal receiving end; the signal receiving end comprises a plurality of relay repeaters which are distributed on a circular ring covered by a mainlobe; each relay repeater forwards received signals at different locations on a phase plane circular ring; the relay repeaters are independent of each other, and the number of the relay repeaters isno less than the mode number of the OAM electromagnetic waves; the signals are forwarded to the central receiver in a wireless or wired way; the central receiver comprises a second receiving and transmitting antenna for receiving the signals relayed and forwarded by the plurality of relay repeaters, a phase plane correction module for carrying on phase plane correction on the distributed transmitted signals, and a demodulation module for demodulating the signals being subjected to phase plane correction. By adopting the system, electromagnetic wave orbital angular momentum transmission of longdistance, high capacity and high spectral efficiency can be realized.

The invention provides a coding method and device. The coding method comprises steps: a transmitting end device superposes a scrambling code bit sequence with a bit sequence after polarization codingto obtain a to-be-transmitted bit sequence; the transmitting end device modulates and maps the to-be-transmitted bit sequence according to a preset modulation mode to obtain to-be-transmitted signals;and the signals are transmitted. By adopting the above technical scheme, the traditional coding modulation scheme is applied to the polarization coding system; as the polarization code itself is extremely low in coding and decoding complexity, the transmitted signals have low complexity, the non-error floor characteristics of the polarization code solve the error floor problem existing in the coding modulation system in a related technology, the above technical scheme introduces polarization mapping in the polarization coding modulation, the system performance is further enhanced, and the high spectral efficiency is realized.

The invention proposes a hybrid beamforming method based on row vector optimization. The algorithm comprises the following steps: step a, establishing a hybrid pre-coding problem model of a millimeterwave MIMO system; step b, calculating an optimal pre-coding matrix by a transmitting end according to channel information and randomly generating an analog pre-coding matrix; step c, solving a digital pre-coding matrix by the transmitting end under an alternately optimized frame; step d, solving the analog pre-coding matrix by the transmitting end under the alternately optimized frame by using amanifold optimization method; and step e, outputting digital pre-coding and analog pre-coding of a transceiving end. The method proposed by the invention can be used for solving the hybrid pre-codingproblem in the millimeter wave MIMO system under multiple situations. The proposed algorithm can achieve higher spectral efficiency with lower complexity, and has certain innovation and practicability.

The invention belongs to the technical field of wireless communication, and discloses a method for designing a hybrid precoder / combiner based on matrix decomposition, which comprises the design of a precoder and a combiner in an analog domain and a digital domain. The design of the analog precoder is based on equal-gain transmission, and the interference between users is eliminated by zeroing theelements on the non-main diagonal of the baseband equivalent channel matrix. The simulation combiner is designed to obtain the maximum antenna array gain, and the orthogonal basis is selected by DFT for each user. The design of digital precoder and combiner is based on matrix block diagonalization. The interference between users is eliminated by matrix QR decomposition, and the stream of each useris parallelized by LDLH decomposition, so as to obtain the maximum spectral efficiency. Numerical results show that the hybrid precoding / combining algorithm can achieve higher spectral efficiency with lower implementation complexity.

The invention discloses a downlink dispatching method and a device. According to the method, all user equipment (UE) which can be dispatched on a resource block i of a community S is confirmed, and in the confirmed UE, the dispatched UE on the resource block i of the community S is confirmed according to dispatched RB quantity of the UE in a preset time window and priority levels of the UE in a channel quality instruction (CQI) of the resource block i of the community S. According to the technical scheme, a transmission rate of a user is increased, and effect of high spectral efficiency is obtained.

A transceiver architecture can contain an encoder and a decoder for communicating high speed transmissions. The encoder can modulate signal data for being mapped in a constellation that is generated based on concatenations of a leech lattice having binary and non-binary codes. The data can be transmitted at a high speed according to the constellation with an embedded leech lattice configuration in order to generate a coding gain. A decoder operates to decode the received input signal data with a decreased latency or a minimal latency with a high spectral efficiency.

The embodiment of the invention relates to the technical field of communication, and discloses a cooperative transmission method and device in a heterogeneous network. According to the method, a CoMP-JP transmission mode and a CoMP-CB transmission mode are utilized for joint cooperative transmission so as to serve macro base station users and micro base station users. Due to the fact that the CoMP-JP transmission mode has higher spectral efficiency and the CoMP-CB transmission mode has the advantage of a larger power utilization space, the cooperative transmission method and device can improve the system energy efficiency of the heterogeneous network.

It is an object of the present invention to provide a method for processing optical signals showing real improvement for the transmission of optical signals over long distance at high bit rate but without implying to high costs. This is achieved by the use of a new modulation format (BL-FSK) based on the generation of a frequency modulated signal. It is obtained by driving an electro-optical modulator (e.g. LiNbO3) with a 1-bit delay pre-coded signal (or some other differential pre-coding) in a similar way as for generating DPSK. But unlike for DPSK, it is advantageously make use of the bandwidth limitation of the electrical and electro-optical components, chosen close to a half of the bit rate (B). A ramp-electrical signal is generated that produces the FSK modulation. As a direct consequence of such modulation, a higher spectral efficiency and a lower cost construction of the transmitter is achieved.

The invention provides a block V-BLAST detection algorithm for a general multi-input multi-output CDMA system over the frequency-selective channels, in which each user's data stream can be either orthogonal space-time block encoded for transmit diversity or spatially multiplexed for high spectral efficiency according to the channel conditions. For such the considered dual-signaling system, the receiver could suffer from the large dimension data processing. A two-stage group V-BLAST detection algorithm is thus proposed to further reduce the computational complexity.

A frequency reuse scheme that provides high spectral efficiency and reduced interference in areas where cell sites overlap is provided. Three frequencies are allocated per cell site, with each sector employing two frequencies, one frequency being transmitted at a higher power and the second frequency being transmitted at a lower power. The higher power frequency in one sector differs from the higher power frequency employed in the other two sectors, and the lower power frequency used in one sector differs from the lower power frequency used in the other two sectors.

The invention discloses a linear digital phase demodulation method for a high-spectral-efficiency coherent optical link, and relates to the technical field of optical communication, the technical field of microwaves and the field of digital signal processing. The method is as shown in figure 1 in the specification, and comprises two lasers CW1 and CW2, a polarization multiplexing Mach-Zehnder modulator PDMMZM, a 25km single-mode optical fiber SMF, two polarization controllers PC1 and PC2, an integrated coherent receiver ICR, an analog-to-digital converter ADC and a digital signal processing module DSP. Intensity modulation and phase modulation are respectively carried out on two radio frequency signals RF in an optical carrier orthogonal polarization state by using PDMMZM, the polarizationstates of a modulated optical signal and a local oscillation optical signal are manually adjusted through two PCs, the modulated optical signal and the local oscillation optical signal are sent to anICR for coherent detection, and then the signals are sent to a DSP module through ADC sampling to complete linear demodulation. According to the invention, coherent detection is combined with a digital signal processing technology to realize signal demodulation. The method has the advantages of high spectral efficiency, good linearity, high sensitivity, capability of effectively suppressing phasenoise and the like.