965 results about "Diversity gain" patented technology

The present invention relates to a method and system for transmitting a transmission signal from an antenna array (19) to a receiving means (20) of a wireless communication system, wherein a signal quality measurement is performed at the receiving means (20) for predetermined antennas or beams of said antenna array (19). Based on a feedback information derived from the signal quality measurement, at least two of the predetermined antennas or beams of the antenna array (19) are selected. The selected antennas or beams are used for transmitting said transmission signal according to a transmit diversity or beamforming scheme. Thus, spectral efficiency and diversity gain can be enhanced by using only selected ones of the predetermined antennas or beams.

An apparatus and a method capable of effectively allocating sub-carriers for a plurality of users and transmitting the sub-carriers to users through multiple antennas in an orthogonal frequency division multiplexing (OFDMA) mobile communication system are provided. A sub-carrier allocation method reduces transmission power by taking a desired bit rate and power budget into consideration. The sub-carriers are optimally allocated to each antenna, so that peak to average power ratio (PARR) is reduced and Quality of Service (QoS) is improved. The apparatus and the method are adaptable for multi-users and obtain space diversity gain through multiple antennas.

The present invention discloses a method for transmitting uplink control channel, a device and a system thereof. In the solution of the invention, after the CCE index and UE corresponding with the first CCE of PDCCH corresponding to the PDSCH resource allocation transmit the PUCCH resource index implicit mapping of PUCCH resource of HARQ-ACK package information, the RB indexes of resource block RB of PUCCH resource which transmits HARQ-ACK package information between two different time slots are respectively RB1,k and RB2,k, k, wherein k is selected from the range from 0 to N-1, and wherein N is the number of carrier component comprising PDSCH. The HARQ-ACK package information is transmitted selectively in the PUCCH resource corresponding with PDSCH on the K'-th carrier component, and k' satisfies the following relationship: k'=arg max(Metric(k)), wherein Metric(k)=abs(RB1,k-RB2,k). The PUCCH resource index of PUCCH resource is nPUCCH, k'. The maximum of RB index difference value means the maximum span length of frequency resource corresponding with two time slots on the frequency domain, thereby a larger frequency diversity gain can be obtained thereby enhancing the transmission efficiency of PUCCH and the transmission quality of whole transmission system is increased.

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 multiple-input multiple-output (MIMO) wireless communication system. A transmitter that includes a plurality of transmit antennas selects one of a spatial multiplexing scheme and a spatial diversity scheme, processes a signal in the selected transmission scheme, and transmits the signal through the plurality of transmit antennas. A receiver that includes a plurality of receive antennas processes a signal in a reception scheme mapped to a transmission scheme of the transmitter. The transmission schemes include a transmission scheme for maximizing diversity gain and a transmission scheme for maximizing spectral efficiency. The MIMO communication system using an adaptive transmission mode switching technique performs switching between MIMO transmission modes using spatial selectivity of a channel, thereby obtaining maximum gain in a signal to noise ratio (SNR) and spectral efficiency according to channel state.

A signal processing apparatus in a multi-input / multi-output (MIMO) communication system includes a transmitting end in which a code rate is differently set and a respectively different modulation method is performed at each antenna in consideration of a channel situation of each transmission antenna, coded bits are separately interleaved, and then collectively interleaved to transmit data, and a receiving end in which received data is collectively deinterleaved and then decoded and deinterleaved separately according to each reception antenna, and a channel situation of each signal received from multiple transmission antennas is estimated and fed back to the transmitting end. A different coding rates and modulation method are used at each transmission antenna and the spatial interleaving is performed to obtain a diversity gain in a space domain, and thus, the communication quality can be enhanced.

A system employs space-time coding characterized at the transmitter by bit-interleaved coded modulation (BICM) combined with modulating several streams of the BICM encoded data for transmission over two or more antennas. Space-time coding techniques improve transmission efficiency in radio channels by using multiple transmit and / or receive antennas and coordination of the signaling over these antennas. Bit-interleaved coded modulation provides good diversity gain with higher-order modulation schemes that employ binary convolutional codes. A receiver demodulates the received signals and applies multi-input, multi-output (MIMO) demapping to estimate the BICM encoded bitstream. After deinterleaving of the BICM encoded bitstream, maximum a posteriori (MAP) decoding is applied to the resulting bit stream to generate soft output values. By applying well-known turbo-decoding principles to iteratively demap and decode, the overall receiver performance is significantly improved. The MIMO demapping and MAP decoding processes exchange likelihood information to improve the bit error rate performance over several iterations of demapping / decoding. By generating tentative decisions for transmitted bits, the overall number of evaluations used for demapping may be reduced.

A MIMO transmitter has a modulator (40,41,42, 120, 122) a demultiplexer 100 arranged to divide the information into one or more demux streams for transmission over different ones of the channels, and a diversity splitter (110) to derive one or more sub-streams of the same information. A decorrelator (120) such as a scrambler (150, 155) decorrelates the sub-streams before or after the modulation. The arrangement is configurable to vary in use a ratio of demultiplexing and of diversity splitting. This balances between the gains from diversity and spatial multiplexing, without needing major changes to the transmit and receive processing.

Provided is a resource allocation method that considers frequency scheduling gain and frequency diversity gain when uplink packet data is transmitted in a wireless communication system based on Orthogonal Frequency Division Multiplexing (OFDM). A method is provided in which Localized Frequency Division Multiple Access (LFDMA) technology capable of obtaining the frequency scheduling gain and Distributed Frequency Division Multiple Access (DFDMA) technology capable of obtaining the frequency diversity gain are mixed. A method is provided which signals sub-carrier sets mapped to the DFDMA and LFDMA, to terminals.

A WLAN distributed / opportunistic scheduling (WDOS) method for acquiring a multi-user diversity gain is disclosed. The WDOS method allows a transmitter (i.e., a transmission user) to observe channel conditions of receivers (i.e., reception users), and commands the transmitter to transmit packets to a specific receiver having a relative good channel condition. The WDOS method uses a modified RTS / CTS exchange method to perform the channel probing. If the transmitter broadcasts the BRTS frame, each receiver transmits a CTS frame after the lapse of its backoff period. According to the reception signal strength distribution, the backoff delay time minimizes the number of CTS collisions irrespective of the number of receivers, reduces an amount of channel probing overheads, and maximizes a multi-user diversity gain. The better the relative channel condition, the lower the backoff delay time.

An STBC encoding extension method for more than two transmit antennas, which provides higher diversity gains while keeping the same coding / decoding latency as in the two-transmit-antenna case of conventional STBC encoding. A N×2 STBC encoder is constructed from a 2×2 STBC encoder, wherein the N×2 STBC encoder is suitable for transmission with higher numbers of transmit antennas including wireless transmission systems with N×1 antenna configurations where N>2.

Disclosed is method of adaptive transmission in an OFDM system with multiple antennas. The adaptive transmission scheme includes an STBC, BLAST, and combined STBC / BLAST. By estimating channel environment, the method selects the proper transmission scheme among the STBC, BLAST, and STBC-BLAST. Therefore, the method has an advantage of each technique, e.g. diversity gain or high transmission rate. By using the method, the reliable and high data-rate communications are achieved.

A diversity receiver is provided with antennas (1a) and (1b) in a first branch and antennas (1c) and (1d) in a second branch each of which antenna gains is controlled so that the offset between the directions of directional radiation patterns for the first and second branches becomes approximately π / 2. Thereby, the diversity receiver can obtain a sufficient diversity gain even when it is incorporated into an indoor television with the antennas being built thereinto in close vicinity to one another.

Multicarrier transmission apparatus 100 receives channel quality information of subcarriers from multicarrier reception apparatus 200 and interleave pattern setting section 108 sets an interleave pattern according to channel quality of subcarriers. Interleaver 106 interleaves I components and / or Q components of symbols using the set interleave pattern. As a result, it is possible to optimize diversity gains in modulation diversity modulation / demodulation according to channel quality.

The invention discloses a multi-input multi-output system, a data transmission method and a data transmission device thereof, which are used for improving the throughput of uplink data transmission inthe multi-input multi-output system. The method comprises that: a user terminal side performs corresponding modulation and coding on a data stream to be transmitted according to received modulation and coding scheme MCS information determined by a base station side, and inserts a user dedicated demodulation reference signal into each data stream to be transmitted respectively; downlink channel estimation is performed, and according to downlink channel information obtained by the estimation, eigenvalue decomposition is performed to obtain a corresponding pre-coding matrix which is used as an uplink pre-coding matrix; and the uplink pre-coding matrix is adopted to pre-code the data stream inserted with the user dedicated demodulation reference signal, and then the pre-coded data stream is transmitted to the base station side. The method and the device fully utilize uplink channel state information to obtain the spatial diversity gain of a plurality of antennae and improve the throughputof the uplink data transmission.

Cooperative communication is a technique that can be employed to meet the increased throughput needs of next generation WiMAX systems. In a cooperative scenario, multiple stations can jointly emulate the antenna elements of a multi-input multi-output system in a distributed fashion. A framework for a randomized distributed space-time coding (“R-DSTC”) technique in the emerging relay-assisted WiMAX network, and the development of a cooperative medium access control (“MAC”) layer protocol, called CoopMAX, for R-DSTC deployment in an IEEE 802.16 system, is described. The technique described couples the MAC layer with the physical (PHY) layer for performance optimization. The PHY layer yields significant diversity gain, while the MAC layer achieves a substantial end-to-end throughput gain.

The present invention relates to a transmitting apparatus of an OFDMA system and a method thereof. The transmitting apparatus includes an encoder for modulating data to be transmitted into data or a preamble by using a desired modulation scheme; an S / P converter for converting serial data output from the encoder to parallel data; a preamble or pilot generator for generating a pilot or preamble; a multiplexer for multiplexing the data or preamble output from the preamble or pilot generator and the parallel data; an antenna selection controller for dividing an entire band of a signal output from the multiplexer into groups formed of neighboring symbols in time domain and neighboring subcarriers in frequency domain, and selecting a transmit antenna for each group; an IFFT unit for turning off subcarriers in groups selected by the antenna selection controller and subcarriers in unselected groups by the antenna selection controller and performing IFFT; for each antenna, a P / S converter for converting parallel signals transmitted from the IFFT unit into serial signals and inserting a cyclic prefix; and for each antenna, a D / A converter and filter for converting a digital signal transmitted from the P / S into an analog signal and filtering the analog signal, and transmitting the filtered analog signal through an antenna of an R / F end. Accordingly, when a transmitting end does not know a channel state of a transmit antenna, a transmit antenna is selected for an allocation unit and data is transmitted through the selected transmit antenna when a transmitting end of an OFDMA system using multiple antennas does not know a channel state, and accordingly a diversity gain can be acquired without making any changes in allocation of subcarriers according to the number of antennas, a transmission structure of a pilot of the transmitting end, an allocation structure of the transmitting end, and a receiving end. In addition, when the transmitting end does know the channel state, an antenna having the best channel state is selected for each group, and accordingly, performance degradation due to feedback delay of channel state information and inter-antenna interference due to an increase of mobility of the terminal can be prevented.

A signal diversity method of an OFDM system comprises the following steps: carrying out data decoding, modulation and rotation-modulation by a transmitting end, and storing the symbols of the processed data blocks; subjecting the symbols of the data blocks of a plurality of users in a memory to grouping and time-frequency interleaving, OFDM time-frequency resource allocation and Q-path interleaving according to the set number of the users, respectively subjecting the symbols of each data block to IFFT operation and CP addition after zero padding according to the OFDM modulation length, then transmitting the data; and subjecting the symbols of the data blocks to de-CP and FFT operations after a receiving end receives the data, carrying out phase compensation and zero removal, and sequentially subjecting the symbols of the obtained data blocks to Q-path de-interleaving, rotation demodulation, time-frequency de-interleaving and coding to obtain the desired data information. By adopting OFDM technique and rotation modulation technique and by selecting an optimal rotation angle, the method can acquire signal diversity gain and maximal performance improvement, thereby improving the system performance.

In a wireless transmitter having a plurality of spatial streams differentiable at a receiver, wherein data is encoded and transmitted over a communication channel with pilot tones to provide the receiver with information about the effects of the communication channel and / or transmitter impairments and / or receiver impairments on the spatial streams transmitted, the benefits can be provided by identifying a plurality of symbol periods within which symbols representing some of the encoded data are to be transmitted, identifying pilot tone values for the plurality of symbol periods, wherein the identified pilot tone values are such that the receiver, when receiving at least some of the pilot tones having the identified pilot tone values, is provided with signals enabling the receiver to characterize the communication channel and / or transmitter impairments and / or receiver impairments to obtain transmit stream diversity gain, and transmitting the symbols and the pilot tones over the plurality of spatial streams for the plurality of symbol periods. In some embodiments, the pilot tones are orthogonal over space and time or over space and time and frequency, while in others they are semi-orthogonal. Pilot tone values might be of a constant amplitude and phase shifted, or might also have amplitude variations wherein at least two pilot tones are nonzero for spatial streams for a given symbol period.

The present invention provides a transmitter having multiple transmitting antennas, comprising: SM / STC apparatus for performing spatial multiplexing or space-time coding diversity on data and for causing resulting signals to be transmitted parallel by multiple transmitting antennas; and a controller for controlling the SM / STC apparatus to operate in SM mode or STC diversity mode in accordance with a signal indicating the operating area which a receiver is located in. The present invention further a corresponding receiver, a base station device and user equipment each comprising the transmitter and receiver of the present invention, and a corresponding method of interference cancellation. The present invention can obtain both diversity gain and interference cancellation gain by performing interference cancellation at the receiver side when interference from other transmitters dominates in the channel. Therefore, the present invention can improve the system capacity and coverage without increasing the base station complexity or decreasing the spectrum usage efficiency at the cell edge.

A MIMO communication system implements an interleaver design with multiple encoders for more than two transmit antennas for high throughput WLAN communication systems. Multiple encoders are utilized in the transmitter and multiple decoders are utilized in the receiver, wherein each encoder operates at lower clock speed than would be necessary with a single encoder. In conjunction with using multiple encoders, a modified interleaving function for each spatial stream processing allows fully exploring the diversity gains. The provided interleaving function is suitable for transmitter architectures with multiple encoders. Similarly, a modified de-interleaving function is provided that is suitable for receiver architectures with multiple decoders.

A system employs space-time coding characterized at the transmitter by bit-interleaved coded modulation (BICM) combined with multi-carrier Orthogonal Frequency Division Multiplexing (OFDM) modulation. Space-Time coding techniques improve transmission efficiency in radio channels by using multiple transmit and / or receive antennas and coordination of the signaling over these antennas. Bit-interleaved coded modulation provides good diversity gain with higher-order modulation schemes that employ binary convolutional codes. OFDM modulation allows for wideband transmission over frequency selective radio channels. A receiver demodulates the OFDM signal and applies multi-input, multi-output (MIMO) demapping to estimate the BICM encoded bitstream. After deinterleaving of the BICM encoded bitstream, maximum a posteriori (MAP) decoding is applied to the resulting bit stream to generate soft output values. The MIMO demapping and MAP decoding processes exchange likelihood information to improve the bit error rate performance over several iterations of demapping / decoding. By applying well-known turbo-decoding principles to iteratively demap and decode, the overall receiver performance is significantly improved.

Provided is a method for dynamic resource allocation of uplink and downlink in an OFDMA / TDD cellular system. The method for dynamic resource allocation of uplink in an OFDMA / TDD cellular system includes the steps of determining the number of sub-channels which can be allocated to each user through an FLR algorithm; performing channel allocation for a first frame through a round-robin algorithm in which channel information is not needed; performing dynamic channel allocation for a next frame through uplink channel information measured by uplink channel sounding; and performing power control. The method for dynamic resource allocation of downlink in an OFDMA / TDD cellular system includes the steps of selecting a user through a GPF algorithm; performing dynamic channel allocation through an ASA algorithm so as to perform a FASA algorithm for obtaining a multiuser diversity gain; and performing dynamic power allocation through an improved CHC algorithm, in consideration of a data rate provided to each user and a channel state.

A single chip diversity beamforming antenna array processor is disclosed. The processor utilizes low-power and low area circuits to achieve combining game mitigate the effects of multipath fading provide spatial suppression and provide diversity gain to a single input receiver. The device is radiofrequency transparent yet provides antenna gain by selective three G and four G code acquisition and tracking of a desired downlink channel.

In a mobile communication system including a transmitter and a receiver, an LDPC code is generated by encoding received information data such that a fifth partial matrix obtained by combining a second partial matrix having even-numbered columns of a first partial matrix corresponding to the information data with a fourth partial matrix having odd-numbered columns of a third partial matrix corresponding to a parity, and an eighth partial matrix obtained by combining a sixth partial matrix having odd-numbered columns of the first partial matrix with a seventh partial matrix having even-numbered columns of the third partial matrix correspond to a ninth partial matrix obtained by exclusive-ORing the first partial matrix and the third partial matrix and a parity check matrix having a predetermined rank in a binary field. A space-time LDPC code is generated by spatial-mapping the LDPC code according to a predetermined spatial mapping scheme.

The present invention relates to a method for coding the hybrid automatic repeat request channel. The method comprises the steps of executing code block dividing to the inputted transmission block according to the maximum allowed coding block of the coder; adding CRC bit to each sub-transmission-block generated after dividing; executing channel encoding to each newly generated sub-transmission-block; executing code rate matching to each subcode stream generated after coding; combining or cascading each subcode stream after code rate matching; executing channel interweaving to the combined or cascaded code stream; mapping the base band of the binary system bit stream after channel interweaving to the planisphere under corresponding modulation mode or orthogonally modulating to the carrier wave; and mapping the modulation symbol to the resource of physical channel. This method increases the performance of chain circuit through making that the coding block has enough diversity gain by configuring the code block cascading before the channel interweaving, and furthermore makes that the transmission has good enough error detection capability and the retransmission time of the coding block is reduced by configuring the CRC bit adding after the code block dividing.

A diversity receiver is provided with antennas (1a) and (1b) in a first branch and antennas (1c) and (1d) in a second branch each of which antenna gains is controlled so that the offset between the directions of directional radiation patterns for the first and second branches becomes approximately π / 2. Thereby, the diversity receiver can obtain a sufficient diversity gain even when it is incorporated into an indoor television with the antennas being built thereinto in close vicinity to one another.

There is provided a radio communication device having a high quality and accuracy regardless of fluctuation degree of the transmission path characteristic. The radio communication device estimates the fluctuation speed of the transmission path characteristic from the time correlation of the reception signal, judges the diversity technique used between the communication devices from the estimated value, and feeds back the judgment information so as to switch the diversity between the communication devices, thereby increasing the diversity gain. The feedback information is minimized by defining a correspondence table. Moreover, diversity switching is performed at a timing considering a control delay and a propagation path delay so as to prevent an instantaneous disconnection of the communication.

Data streams stored in buffers (101) are modulated by modulation sections (102). Multipliers (103) multiply the signals output from the modulation sections (102) by weights output from a weight control section (112). The signals output from the multipliers (103) are added up by addition sections (104), subjected to radio transmission processing by transmission radio sections (105) and sent through antennas (106). A buffer control section (111) controls the buffers (101) based on a retransmission count output from a retransmission count detection section (110). The weight control section (112) outputs weights different from weights at the time of previous transmission to the multipliers (103) every time data is retransmitted. This allows a diversity gain at the time of data retransmission to be increased even if a time variation of the propagation path environment for radio signals is slow.

A coding technique for achieving a maximum diversity gain in a wireless communication system having a transmitter for transmitting data on a fading channel through a plurality of transmit antennas and a receiver for receiving the data through a plurality of receive antennas. In the coding technique, P mth-order sub-rotated vectors {right arrow over (r)}i are generated by constellation-rotating an Lth-order input vector {right arrow over (x)} including a plurality of input symbols modulated in at least one modulation scheme. m pth-order sub-vectors {right arrow over (u)}i are generated using the sub-rotated vectors {right arrow over (r)}i. Codeword matrices Ai({right arrow over (u)}i) are generated by performing orthogonal space-time block coding on the sub-vectors {right arrow over (u)}i and then transmitted through the transmit antennas.