81 results about "Space time frequency" patented technology

A method and system for cooperative multiple-input multiple output (MIMO) transmission operations in a multicell wireless network. Under the method, antenna elements from two or more base stations are used to from an augmented MIMO antenna array that is used to transmit and receive MIMO transmissions to and from one or more terminals. The cooperative MIMO transmission scheme supports higher dimension space-time-frequency processing for increased capacity and system performance.

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

A space-time-frequency block coding apparatus and method in a transmitter with three transmit (Tx) antennas are provided. An input symbol sequence is transmitted through three Tx antennas according to a permutation method using a selected transmission matrix in order to improve the performance of an STFBC.

Techniques are described for space-time-frequency (STF) coding of multi-carrier transmissions over frequency-selective fading channels. In particular, techniques for STF coding of MIMO-OFDM systems are described that provide maximum diversity, high coding gains, and low decoding complexity are described. A set of generally correlated OFDM subcarriers are divided into groups of subcarriers creating a set of group STF (GSTF) subsystems, within which STF coding is applied to each GSTF subsystem. Subcarrier grouping preserves maximum diversity gains and simplifies both the code construction within each GSTF and decoding complexity. ST coding techniques are used in designing STF block (STFB) and STF trellis (STFT) codes which are applied within GSTF subsystems.

A space-time-frequency domain based information feedback method, system, user equipment and base station for wireless transmission technical fields is provided. The user equipment measures and evaluates quality of wireless transmission downlinks in MIMO system, obtains rank, precoding matrix index and channel quality indicator information in the wireless transmission downlinks, processes information of the wireless transmission downlink respectively in space domain, frequency domain and time domain by using space selectivity, frequency selectivity and time selectivity characteristics of a channel, and feeds back downlink information to the base station through uplinks by using feedback schemes. The base station optimizes a transmitter according to feedback information from the user equipment.

A method detects unused frequency bands in a cognitive radio network. Multiple frequency bands for RF signals are sensed using an antenna array including a plurality of elements coupled to a receive RF chain, in which the plurality of elements are individually controllable. For each frequency band, multiple spatial directions are sensed for the RF signals using the antenna array. A particular frequency band and a particular direction and a particular time slot are assigned as an available frequency band, an available direction and a particular time slot for transmitting RF signals in a cognitive radio if the RF signals are not sensed in the particular spatial direction for the particular frequency band, and in which the RF signals are transmitted by a transmit chain connected to the antenna array.

The invention relates to a method for feeding information back on the basis of space time frequency domain, a system, a user device and a base station thereof, which are used in the technical field of wireless transmission, the user device in the invention measures and estimates the quality of a wireless transmission chain circuit of a downlink MIMO system, information such as order, pre-coding matrix key number, communication channel quality indication and the like of the downlink wireless transmission chain circuit is obtained, the selecting characteristics of the communication channel in three dimensional space of spatial domain, frequency domain and time domain are utilized to process the information of the downlink wireless transmission chain circuit in the spatial domain, the frequency domain and the time domain respectively, a feedback method which is used effectively and simply is used to transmit the information of the downlink chain circuit to the base station, the base station optimizes a transmitter according to the information which is fed back by the user device, and thereby the purpose of improving the whole data throughput of a wireless district and the data throughput of the district edge under the precondition that the service quality of the wireless district is considered is achieved.

A method and system for cooperative multiple-input multiple output (MIMO) transmission and reception operations in a multicell wireless network. Under the method, antenna elements from multiple base stations and / or multiple antennas are utilized to from an augmented MIMO antenna array that is used to transmit and receive MIMO transmissions at base stations and / or terminals. The cooperative MIMO transmission scheme supports higher dimension space-time-frequency processing for increased capacity and system performance.

A Space-Time-Frequency Block Coding (STFBC) encoding apparatus and method for a wireless communication system are provided. In a transmitter using a plurality of transmit antennas, an encoder encodes an input symbol sequence according to a predetermined space-time coding matrix. An antenna circulator selects one of predetermined permutation matrices according to a predetermined formula and generates a plurality of symbol vectors by permuting the space-time coded symbols according to the selected permutation matrix.

Maximum diversity in multiple antenna distributed frequency broadband systems such as MIMO-OFDM is achievable through space-frequency (SF) and space-time-frequency (STF) coding. Full-rate full-diversity coding is achieved through a combination of maximal minimum product distance symbol set design and formation of codeword blocks. Full-diversity codes are also achieved which have reduced symbol transmission rates, such as through mapping of space-time (ST) codes to SF codes. The reduction in symbol rate may be offset by the fact that any ST code may be mapped to a full-diversity SF code.

A method detects unused frequency bands in a cognitive radio network. Multiple frequency bands for RF signals are sensed using an antenna array including a plurality of elements coupled to a receive RF chain, in which the plurality of elements are individually controllable. For each frequency band, multiple spatial directions are sensed for the RF signals using the antenna array. A particular frequency band and a particular direction and a particular time slot are assigned as an available frequency band, an available direction and a particular time slot for transmitting RF signals in a cognitive radio if the RF signals are not sensed in the particular spatial direction for the particular frequency band, and in which the RF signals are transmitted by a transmit chain connected to the antenna array.

Multiple wireless user devices act cooperatively to communicate with a remote destination node through a MIMO channel. In at least one embodiment, a cooperative cluster of user devices is formed that makes use of vertical coding techniques to achieve enhanced communication performance.

A space-time-frequency block coding apparatus and method in a transmitter with three transmit (Tx) antennas are provided. An input symbol sequence is transmitted through three Tx antennas according to a permutation method using a selected transmission matrix in order to improve the performance of an STFBC.

A transmitter for maximizing coding gain by transmitting an input symbol sequence through a plurality of transmit antennas method according to feedback CQIs from a receiver in a 3 Tx-rate 2 communication system. In the transmitter, an S / P converter converts serial modulated data to parallel modulated data. A coder mode decider determines a transmission mode based on the channel quality indicator of each transmit antenna fed back from a receiver. A coder transmits the parallel modulated data through the three transmit antennas according to the determined transmission mode.

A method for space-time-frequency coding pieces of data includes receiving a stream of a plurality of pieces of data in a multi-antenna transmission system, where the data may comprise a stream of orthogonal frequency division multiple access (OFDMA) symbols, orthogonal frequency division multiplexed (OFDM) symbols or the like. The pieces of data are then coded across space, time and frequency dimensions based upon a plurality of space-time-frequency (STF) codes. The pieces of data are coded such that one or more STF codes in the frequency dimension differ from one or more other STF codes in the frequency dimension. In this regard, the frequency dimension can include a plurality of frequency bins such that the pieces of data can be coded in a manner whereby the plurality of STF codes sequentially circulates through sets of at least one frequency bin in the frequency domain.

The present invention provides a space-time-frequency block coding apparatus and method in a transmitter with three transmit(Tx) antennas. An input symbol sequence is transmitted through three Tx antennas according to a permutation method using a selected transmission matrix in order to improve the performance of an STFBC.

A method and system realize reliable wireless communications in non-coherent multiple-input multiple-output (MIMO) doubly-selective channels. The method uses Grassmannian space-time-frequency block codes and an iterative generalized likelihood ratio test (GLRT) with a multi-dimensional basis expansion model (BEM), decision reordering, and a fixed number of surviving candidates. The computational complexity of a non-coherent MIMO equalizer becomes linear as a function of a code length and a size of a modulation alphabet. The codebook, the alphabet size, the bit labeling, and the block power are optimized using worst-case channel statistics or instantaneous channel states. The method can use soft-information feedback from error correction codes, such as low-density-parity-check codes to improve performance.

A Space-Time-Frequency Block Coding (STFBC) encoding apparatus and method for a wireless communication system are provided. In a transmitter using a plurality of transmit antennas, an encoder encodes an input symbol sequence according to a predetermined space-time coding matrix. An antenna circulator selects one of predetermined permutation matrices according to a predetermined formula and generates a plurality of symbol vectors by permuting the space-time coded symbols according to the selected permutation matrix.

The invention provides a wave beam domain time-frequency analysis method for warship line spectrum noise source positioning. The wave beam domain time-frequency analysis method comprises the following steps: performing frequency domain filtering and super-directivity beam forming to the signals received by an array, that is, performing spatial filtering and constituent isolation on the time domain, so as to realize space-time-frequency domain combined processing of the signals; estimating the abeam moment of each line spectrum noise source, and referring to the synchronous acoustic beacon information to estimate the longitudinal position distribution of the line spectrum noise source along the warship. The wave beam domain time-frequency analysis method disclosed by the invention adopts the high-order super-directivity beam forming algorithm to greatly shrink the physical size of the receiving array and improve the actual operability of the measuring method on the premise of maintaining the receptivity; the space-time-frequency domain combined processing to the received signals is used for extracting the signal constituents of each line spectrum noise source; the time-frequency analysis method is used for obtaining the accurate time-frequency domain distribution diagram of the Doppler signals and accurately estimating the Doppler inflexions, so as to realize noise source position estimation of the high-precision multi-line spectrum and the same-frequency line spectrum.

A space-time-frequency block coding apparatus and method in a transmitter with three transmit (Tx) antennas are provided. An input symbol sequence is transmitted through three Tx antennas according to a permutation method using a selected transmission matrix in order to improve the performance of an STFBC.

A maneuvering target parameter estimation method based on compressed sensing comprises the following steps: estimating a clutter covariance matrix by using data of a reference unit, restraining clutter to data of a unit under a test, scattering coming directional angle space, speed space and acceleration space of a objective, establishing objective space-time frequency three dimensional parameters according to scattered parameter space and estimating required base dictionary, obtaining objective parameter rough estimating values based on compressed sensing through sparse solution and recording the objective parameter rough estimating values as construction cost function, raking in a local range with the rough estimating values as domain to achieve objective parameter accurate estimate, and obtaining final estimating results. The maneuvering target parameter estimation method based on the compressed sensing can be used for realizing that an airborne phased array radar accurately estimates space-time frequency three dimensional parameters of an air maneuvering objective.

In a wireless wideband MIMO-OFDM transmission system, a method includes converting a coded bit sequence to parallel data layers, responsive to channel encoding and interleaving of an information sequence to provide the coded bit sequence; passing each data layer through a respective repetition encoder, independently interleaving respective spread data sequences from the respective repetition encoder, and amplifying the respective interleaved outputs responsive to power allocation of a respective layer of multiple layers for both I and Q channels for being combined to form complex symbols for transmission through respective multiple antennas.

The invention discloses a differential encoding space-time-frequency modulation method, and belongs to the technical field of wireless communication. The method comprises that: a mobile terminal of a communication system performs space-time encoding on an information bit sequence required to be transmitted to generate a unitary matrix code word sequence; the unitary matrix code word sequence is subjected to differential modulation to generate a matrix sequence to be transmitted; symbols in the matrix sequence to be transmitted are respectively mapped to a space domain, a time domain and a frequency domain so as to acquire a group of space-time-frequency three-dimensional signals; a plurality of groups of transmission signals are acquired through OFDM modulation, and each group of transmission signals is transmitted through a transmitter antenna; and the OFDM modulation and differential demodulation are directly carried out a receiving end, and required information is acquired. Through differential space-time-frequency block code mapping or differential space-time-frequency cyclic code mapping, the encoding and the differential modulation are respectively carried out at different dimensionalities, so that a requirement of a channel on relevance of the time domain and the frequency domain is reduced, and a requirement of reliable signal transmission in high-speed mobile environment in a wideband communication system can be met.

The invention provides a rectangular tunnel wireless propagation channel modelling method for a statistical channel model for a tunnel V2V scattering environment. A uniform linear antenna array is provided for each of a mobile transmitter and a receiver; supposing that scatters are freely distributed on a tunnel wall, and the transmitter and the receiver are located in mobile state; LOS and NLOS scattering conditions are considered in a rectangular tunnel scattering region; a 3D tunnel geometric model is analyzed to obtain a space-time frequency mutual-correlation function, a time self-correlation function and a frequency correlation function. For verifying the rationality and feasibility of the model, the theoretical parameter and a reference model are contrasted, a result shows that thetime self-correlation function and the frequency correlation function of the model conform to a reference channel model. And meanwhile, the influence on the Doppler power spectrum density and the MIMOchannel capacity by the model parameters is researched. By computing the statistical feature parameters of the rectangular channel, the tunnel V2V communication system performance is improved.

The invention discloses a signal transmission and reception method of a multi-carrier MIMO (multiple input multiple output) system based on a chip-level spread spectrum code of a space-time-frequency three-dimensional complementary code, relating to an MIMO system based on a chip-level spread spectrum code of a space-time-frequency three-dimensional complementary code. Through the invention, the problem of poor multi-path interference resistance of the MIMO system adopting the existing coding mode is solved; and the existing coding mode is only applicable to the condition that the channel response is in slow fading, namely that the channel response is kept unchanged for sure within the time of the symbol bits. A transmitting end of the multi-carrier MIMO system performs spectrum spread by using the chip-level spread spectrum code of the space-time-frequency three-dimensional complementary code; and a receiving end performs de-spreading operation by using the chip-level spread spectrum code of the space-time-frequency three-dimensional complementary code. The multi-path interference resistance of the MIMO system disclosed by the invention is greatly improved, and the MIMO system is suitable for wireless communication processes.

Methods, a base station and computer programs for performing multiple access in wireless OFDM cellular systems over multipath wireless channels considering both space and frequency domains,The base station 100 comprises a large number of antennas 103 in the form of a two-dimensional array and transmits a given number of signals to a number of users 106, so that each one receives its intended signal (or set of intended signals) without interference to / from the other users 106. The base station 100 includes a scheduler in space-time-frequency dimensions 101 as well as an orthogonal space-frequency processing technique 102 for addressing the users 106. The cellular scenario is assumed where the wireless channel 105 presents significant multipath, thereby resulting in multiple signal components being received by each user 106. Orthogonality of the beams is achieved upon transmission by properly discretizing the spatial domain, while inter-user interference is avoided by exciting only those beams that result in multipath components received by one single user 106.