24661results about "Spatial transmit diversity" patented technology

Channel state information (CSI) can be used by a communications system to precondition transmissions between transmitter units and receiver units. In one aspect of the invention, disjoint sub-channel sets are assigned to transmit antennas located at a transmitter unit. Pilot symbols are generated and transmitted on a subset of the disjoint sub-channels. Upon receipt of the transmitted pilot symbols, the receiver units determine the CSI for the disjoint sub-channels that carried pilot symbols. These CSI values are reported to the transmitter unit, which will use these CSI values to generate CSI estimates for the disjoint sub-channels that did not carry pilot symbols. The amount of information necessary to report CSI on the reverse link can be further minimized through compression techniques and resource allocation techniques.

Exploiting the substantive reciprocity of internode channel responses through dynamic, adaptive modification of receive and transmit weights, enables locally enabled global optimization of a multipoint, wireless electromagnetic communications network of communication nodes. Each diversity-channel-capable node uses computationally efficient exploitation of pilot tone data and diversity-adaptive signal processing of the weightings and the signal to further convey optimization and channel information which promote local and thereby network-global efficiency. The preferred embodiment performs complex digital signal manipulation that includes a linear combining and linear distribution of the transmit and receive weights, the generation of piloting signals containing origination and destination node information, as well as interference-avoiding pseudorandom delay timing, and both symbol and multitione encoding, to gain the benefit of substantive orthogonality at the physical level without requiring actual substantive orthogonality at the physical level.

A communication method and apparatus using analog and digital hybrid beamforming are provided. The method includes receiving a first message including a measurement and selection condition for hybrid beamforming from a Base Station (BS), measuring channels of a plurality of BS transmission beams, selecting at least one BS transmission beam based on channel measurements, transmitting report information about the selected at least one BS transmission beam to the BS, receiving from the BS a second message, estimating an effective channel matrix for the selected final BS transmission beam according to the measurement and report condition, determining feedback information for digital beamforming of the BS based on the effective channel matrix, transmitting the determined feedback information to the BS, and receiving a data burst from the BS according to a Multiple Input Multiple Output (MIMO) mode and/or a configuration scheduled based on the feedback information.

The present invention provides methods and apparatus for implementing spatial multiplexing in conjunction with the one or more multiple access protocols during the broadcast of information in a wireless network. A wireless cellular network for transmitting subscriber datastream(s) to corresponding ones among a plurality of subscriber units located within the cellular network is disclosed. The wireless cellular network includes base stations and a logic. The base stations each include spatially separate transmitters for transmitting, in response to control signals, selected substreams of each subscriber datastream on an assigned channel of a multiple access protocol. The logic communicates with each of the base stations. The logic assigns an available channel on which to transmit each subscriber datastream. The logic routes at least a substream of each datastream to at least a selected one of the base stations. The logic also generates control signals to configure the at least a selected one of the base stations to transmit the selected substreams to a corresponding one among the plurality of subscriber units on the assigned channel. A subscriber unit for use in a cellular system is also disclosed. The subscriber unit includes: spatially separate receivers, a spatial processor, and a combiner. The spatially separate receivers receive the assigned channel composite signals resulting from the spatially separate transmission of the subscriber downlink datastream(s). The spatial processor is configurable in response to a control signal transmitted by the base station to separate the composite signals into estimated substreams based on information obtained during the transmission of known data patterns from at least one of the base stations. The spatial processor signals the base stations when a change of a spatial transmission configuration is required. The combiner combines the estimated substreams into a corresponding subscriber datastream.

Apparatus and methods implement aggregation frames and allocation frames. The aggregation frames include a plurality of MSDUs or fragments thereof aggregated or otherwise combined together. An aggregation frame makes more efficient use of the wireless communication resources. The allocation frame defines a plurality of time intervals. The allocation frame specifies a pair of stations that are permitted to communicate with each other during each time interval as well as the antenna configuration to be used for the communication. This permits stations to know ahead of time when they are to communicate, with which other stations and the antenna configuration that should be used. A buffered traffic field can also be added to the frames to specify how much data remains to be transmitted following the current frame. This enables network traffic to be scheduled more effectively.

A receiver of the present invention addresses the need for improved interference suppression without the number of transmissions by the power control system being increased, and, to this end, provides a receiver for a CDMA communications system which employs interference subspace rejection to tune a substantially null response to interference components from selected signals of other user stations. Preferably, the receiver also tunes a substantially unity response for a propagation channel via which a corresponding user's signal was received. The receiver may be used in a base station or in a user/mobile station.

Systems and methods of optimizing communication channels in multi-user communication systems are provided. Coding weights are determined based on communication channel state information for communication channels between a transmitter and multiple receivers. The coding weights are applied to communication signals to be transmitted from the transmitter to the receivers. Each receiver decodes received signals using inverses of the coding weights. Embodiments of the invention support multi-user MIMO (Multiple Input Multiple Output) where each receiver has fewer antennas than the transmitter, and enhance system performance if the total number of antennas at all of the receivers exceeds the number of antennas at the transmitter.

Methods and apparatus are provided for communicating data in a multiple antenna communication system having N transmit antennas. According to one aspect of the invention, a header format includes a legacy preamble having at least one legacy long training field and an extended portion having at least N additional long training fields on each of the N transmit antennas. The N additional long training fields may be tone interleaved across the N transmit antennas and are used for MIMO channel estimation. The extended portion may include a short training field for power estimation. The short training field may be tone interleaved across the N transmit antennas and have an extended duration to support beam steering.

The distortion in the sub-carrier signals is determined by transmitting known values that are incorporated into the preamble portion of the frame and/or are incorporated into pilot symbols that are inserted into the data portion of the frame. The receiver typically receives these known values in a distorted form and then processes the distorted values together with the original known values to obtain a channel response. The channel response is then used to estimate the frequencies at which the channels are received.

Closed loop wireless communication of signals using an adaptive transmit antenna array (3), in which a plurality of copies of signals to be transmitted by the transmit antenna array (3) are produced with delays and weights (w_n^j) that are functions of the multi-path transmission channel characteristics (H) from the transmit antenna array (3) to a receive antenna array (4) of a receiver (2) and are combined before transmission by the transmit antenna array. The delays and weights (w_n^j) of the transmit copies for each transmit antenna element are functions of the respective multi-path transmission channel characteristics $\left(h_{n,m=1}^{l=1},\dots ,h_{n,m=M}^{l=L}\right)$

from that transmit antenna element to the receive antenna array (4) ssuch that the multi-path signal components propagated to each receiver element are received with distinguishable delays according to the propagation path. The receiver (2) combines the received signal components from each receive antenna element with delays and weights (u) that are respective functions of the multi-path transmission channels.

Preferably, the receiver comprises a multi-finger RAKE receiver (6) that copies the received signals from the receive antenna array with delays and weights (u) that are respective functions of the multi-path transmission channels and combines the copied received signals.

A method of transmitting/receiving channel quality information (CQI) of subcarriers in an OFDM system where data is transmitted on the subcarriers via one or more transmit antennas. The subcarriers are grouped into subcarrier groups each having at least one subcarrier and further grouped into subgroups each having one or more subgroups. A user equipment generates CQIs for one or more allocated subcarrier groups and the transmit antennas or CQIs for the allocated subcarrier groups, the subgroups of the subcarrier groups, and the transmit antennas. The group CQIs and the subgroup CQIs are transmitted to a Node B in one or more physical channel frames.

Frequency-independent eigensteering in MISO and MIMO systems are described. For principal mode and multi-mode eigensteering, a correlation matrix is computed for a MIMO channel based on channel response matrices and decomposed to obtain N_S frequency-independent steering vectors for N_S spatial channels of the MIMO channel. ND data symbol streams are transmitted on N_D best spatial channels using N_D steering vectors, where N_D=1 for principal mode eigensteering and N_D>1 for multi-mode eigensteering. For main path eigensteering, a data symbol stream is transmitted on the best spatial channel for the main propagation path (e.g., with the highest energy) of the MIMO channel. For receiver eigensteering, a data symbol stream is steered toward a receive antenna based on a steering vector obtained for that receive antenna. For all eigensteering schemes, a matched filter is derived for each receive antenna based on the steering vector(s) and channel response vectors for the receive antenna.

A communication station employs discontinuous transmission of channel quality feedback to reduce channel quality feedback transmitted over overhead channels. Prior to transmitting channel quality information to a remote station, the communication station compares the channel quality feedback to predetermined qualification criteria. If the qualification criteria are not met, the channel quality feedback is not transmitted. The method may be implemented by a mobile station to reduce channel quality feedback sent to a base station over a reverse link overhead channel.

In a multiuser Multiple Input Multiple Output (MIMO) radio communication system, a transmitter receives channel quality information transmitted from receivers, schedules resource for the receivers within a corresponding scheduling epoch based on the received channel quality information. Thereafter, the transmitter pre-codes signals to be transmitted to the resource-scheduled receivers in a predetermined coding method before transmission, thereby maximizing system transmission efficiency.

A wireless communication network includes a plurality of mobile nodes each including a transceiver, a phased array antenna connected to the transceiver, and a controller connected to the transceiver. The controller schedules a respective semi-permanent time slot for each time frame to establish a communication link with each neighboring mobile node and leaves at least one available time slot in each time frame. The controller also schedules the at least one available time slot to also serve the communication link with a neighboring mobile node based upon link communications demand. The phased array antenna is aimed by the controller towards each neighboring mobile node during communication therewith. The controller also detects interference in time slots for communication with neighboring mobile nodes and coordinates the scheduling of time slots based upon detected interference.

The present invention makes it possible to increase a data rate between a transmitter and receiver using a multiple-input, multiple-output radio frequency channel. A multiple-stream, multiple-antenna receiver measures a composite channel between a multiple-antenna transmitter and a multiple-antenna receiver to produce a composite channel measurement. The receiver selects a plurality of antenna array weight sets for use in the multiple-antenna transmitter in response to the composite channel measurement, where each antenna array weight set is associated with one of multiple data streams. Information describing the plurality of antenna array weight sets for use in the multiple-antenna transmitter are then transmitted.

In a MIMO system the signals transmitted from the various antennas are processed so as to improve the ability of the receiver to extract them from the received signal even in the face of some correlation. More specifically the number of bit streams that is transmitted simultaneously is adjusted, e.g., reduced, depending on the level of correlation, while multiple versions of each bit stream, variously weighted, are transmitted simultaneously. The variously weighted versions are combined to produced one combined weighted signal. The receiver processes the received signals in the same manner as it would have had all the signals reaching the receive antennas been uncorrelated. The weight vectors may be determined by the forward channel transmitter using the channel properties of the forward link which are made known to the transmitter of the forward link by being transmitted from the receiver of the forward link by the transmitter of the reverse link or the weight vectors may be determined by the forward channel transmitter using the channel properties of the forward link and the determined weight vectors are made known to the transmitter of the forward link by being transmitted from the receiver of the forward link by the transmitter of the reverse link. The channel properties used to determine the weight vectors may include the channel response from the transmitter to the receiver and the covariance matrix of noise and interference measured at the receiver.

MIMO transmission methods are applied to communicaiton systems in which a transmitter has more than one transmit antenna and a receiver has more than one receive antenna. Information to be transmitted is divided into a plurality of subsignals according to the number of used transmit antennas and each subsignal is processed separately before it is emitted by the respective transmit antenna. In the receiver the different receive signals are processed thus that subsignals are detected and decoded and the contribution of each detected and decoded subsignal is subtracted from the receive signals and whereby a feedback channel from receiver to transmitter is used to send control information to the transmitter depending on the receive situation. In order to optimize the usage of the MIMO channel the invention proposes the in the receiver the link quality of each subsignal is determined and information of each subsignal is transmitted to the receiver via the feedback channel and that in the transmitter properties of the subsignals are controlled by the link quality information.

Two-way (full-duplex) wireless communications. Various embodiments measure interference channels and provide for interference cancellation in both analog and digital domains to mitigate self-interference. The system supports multiple clients wherein new clients can join the network asynchronously, and also supports Multiple-Input Multiple-Output (MIMO) antennas.

Aspects of the present invention provide additional MAC functionality to support the PHY features of a wireless communication system framework. The additional MAC functionality aids in enabling feedback from wireless terminals to base stations. In some aspects of the invention the feedback is provided on an allocated feedback channel. In other aspects of the invention the feedback is provided by MAC protocol data units (PDU) in a header, mini-header, or subheader. The feedback may be transmitted from the wireless terminal to the base station autonomously by the wireless terminal or in response to an indication from the base station that feedback is requested. Aspects of the invention also provide for allocating feedback resources to form a dedicated feedback channel. One or more of these enhancements is included in a given implementation. Base stations and wireless terminals are also described upon which methods described herein can be implemented.

A pilot (or reference) transmission scheme is utilized where different transmitters are assigned pilot sequences with possibly different cyclic time shifts. A pilot signal is transmitted concurrently by the transmitters in a plurality of pilot blocks, and a receiver processes the plurality of received pilot blocks to recover a channel estimate for at least one of the transmitters while suppressing the interference due to the pilot signals from the other transmitters.