161 results about "Channel reciprocity" patented technology

The invention relates to a signal processing method which optimizes the bit error rate under pragmatic conditions. The signalling method is optimally matched to the radio channel, variable with time, in rapid sequence by means of linear operations. Uplink and downlink transmission sides are determined by an excess of antennae on the downlink transmission side. The estimations of the channel matrix in the one transmission direction, necessary for the matching of the transmitter, can, in the absence of common-channel distortions with the condition of channel reciprocity, be directly obtained from the estimations for the other transmission direction. By a suitable linear combination of the transmission signals and, optionally, also the received signals, an error-free bi-directional transmission of data streams can be achieved in Rayleigh and Rice channels with significantly lower transmission powers than in purely receiver-side linear signal processing.

The present invention relates to a method and arrangement to enhance the communication performance in wireless communication systems. The method of the invention provides a method of calibrating at least one first radio node in a wireless communication network. The communication network comprises at least a first radio node and a second radio node, which can be arranged to be in radio communication with each other. The calibration method is based on that at least one representation of radio channel characteristics, which has been exchanged from one radio node to the other. Whereby inaccuracies and differences in transmit receive chains are compensated and channel reciprocity can be used.

The invention provides a pre-coding method for a multi-user MIMO (multi-input multi-output) system. The method comprises the following steps of: acquiring a channel matrix of each user of the system by feedback or TDD (time division duplex) system channel reciprocity; acquiring a channel pseudo-inverse matrix of each user of the system according to the least square error criterion; acquiring an orthogonal vector base matrix according to a channel pseudo-inverse sentence of each user of the system; acquiring a pre-coding merging matrix of each user of the system according to the channel matrixof each user of the system and the channel pseudo-inverse orthogonal vector base matrix by combining a max signal to leakage and noise ratio criterion; and acquiring a pre-coding matrix of each user of the system according to the orthogonal vector base matrix of each user of the system and the optimal merging matrix. The scheme can effectively reduce the calculation complexity of the scheme at the same time of keeping the performance of the original MSLNR (max signal to leakage and noise ratio) criterion scheme, the performance of the scheme is superior to that of the traditional diagonal scheme, and the scheme has lower calculation complexity and reduces the operating complexity of a base station.

A base station that communicates with a user equipment using multiple antenna ports includes an uplink channel estimation unit that estimates uplink channel states, a downlink channel estimation unit that estimates downlink channel states based on the estimated uplink channel states and channel reciprocity of uplink and downlink, a receiver unit that receives from the user equipment CSI feedback information, and a precoder generating unit that determines a precoding matrix of downlink based on Channel State Information (CSI) indicating the estimated downlink channel states and on the CSI feedback information.

The embodiment of the invention discloses a feedback method and equipment for signal channel quality information. Through the adoption of the technical scheme provided by the embodiment of the invention, terminal equipment calculates channel quality indicator (CQI) information under the condition of hypothetical closed loop pre-coding, factors such as receiving processing algorithms at the terminal equipment side and the like can be more accurately reflected, a base station can be combined with the corresponding CQI information and the signal channel reciprocity processing through the feedback of the CQI information, and more accurate signal channel information can be obtained for carrying out more accurate resource dispatching, so the system performance is improved.

The invention discloses a method and a device for sending a measurement reference signal. The method comprises the following steps that: user equipment select an antenna or an antenna group to send the measurement reference signal, wherein the user equipment determine the antenna or the antenna group for sending the measurement reference signal according to an antenna mapping rule, or an antenna selection rule or an antenna selection mask in the format of downlink control information. With the technical scheme of the invention, the problem of reciprocity of some channels caused by the traditional standard methods is solved, so that a base station end can obtain integral downlink CSI (Channel State Information) based on the channel reciprocity, and the optimal pre-coding matrix can be used for each PRB (Physical Resource Block) during downlink transmission so as to obtain frequency selective pre-coding gain.

Methods for WiFi beamforming, feedback, and sounding (WiBEAM) are described. Codebook based beamforming feedback signaling and sounding mechanisms for use in wireless communications are disclosed. The methods described herein improve the feedback efficiency by using Givens rotation based decompositions and quantizing the resulting angles of the Givens rotation based decompositions using a range from a subset of [0, 2π]. Feedback may also be divided into multiple components to improve feedback efficiency/accuracy. Time domain beamforming reports for taking advantage of channel reciprocity while still taking into account practical radio frequency (RF) channel impairments are also described. Beamforming feedback that prioritizes the feedback bits in accordance with the significance of the bits is also disclosed. A preamble structure to enable the use of smoothing methods for improved channel estimation, codebook designs that may be used for codebook based beamforming feedback, and multi-resolution explicit feedback are disclosed as well.

The invention discloses a reciprocity loss compensation method of a 2*2 TDD-MIMO system channel, which mainly solves the problem of channel reciprocity loss caused by in-phase/orthogonal I/Q imbalance in a TDD-MIMO system. In the method, a base station BS and a mobile station MS first measure respectively received direction channels to obtain channel state information CSI of an uplink and a downlink; then converging the CSI of the two links to the BS, and the BS calculates the calibration matrixes respectively used for the BS and the MS; sending the calibration matrix used by the MS to the MS; and when in formal data transmission, the BS and the MS use the respective calibration matrixes to pre-process signals to be sent so as to maintain the channel reciprocity of the uplink and the downlink. The method has the advantages of easiness, good effect and little spending of the system, and is applicable in compensating for the loss of the TDD-MIMO system channel caused by I/Q imbalance.

The invention relates to a power control method of a TD-LTE system. In the method, a user forecasts the up interference of an adjacent base station on a corresponding cell by estimating the down channel of the adjacent base station by utilizing the channel reciprocity of the uplink and the downlink of the TD-LTE system; on the basis of interference forecast, the user can actively regulate transmitting power per se so as to reduce the interference to an adjacent cell. The invention does not need to change the current power control flow and signalling, has good compatibility, can effectively reduce intracell interference level and improves the cell edge user throughput and system throughput.

The present invention relates to a method and arrangement to enhance the communication performance in wireless communication systems. The method of the invention provides a method of calibrating at least one first radio node in a wireless communication network. The communication network comprises at least a first radio node and a second radio node, which can be arranged to be in radio communication with each other. The calibration method is based on that at least one representation of radio channel characteristics, which has been exchanged from one radio node to the other. Whereby inaccuracies and differences in transmit receive chains are compensated and channel reciprocity can be used.

The invention discloses an antenna calibrating method and an antenna calibrating device used in a time division duplex coordinated multiple point system. The antenna calibrating method comprises a step of calibrating antennas among cells by a network side: selecting a standard antenna, taking the standard antenna as the standard, and calibrating reference antennas in all the cells; and a step of calibrating the antennas in the cells by the network side again: taking the reference antenna of the cell as the standard in each cell, and calibrating other antennas in the cell, excepting the reference antenna, wherein one of the antennas of the cell is selected as the reference antenna of the cell in each cell respectively. By using the protocol of calibrating the antennas among the cells firstly and then calibrating antennas in the cell on the basis of calibration among the cells, the reciprocity of an uplink and a downlink in the calibrated cell cannot be damaged; the channel reciprocity performance of the time division duplex (TDD) coordinated multiple point (CoMP) system is improved, so that the transmission performance of the CoMP system is also improved.

The invention belongs to the field of wireless communication, and discloses a key generation method capable of ensuring the security of wireless communication. The key generation method is based on a wireless channel reciprocity and a curve fitting method, extracts a shared key of wireless communication users from a shared wireless channel state to ensure the communication security, and specifically comprises five steps consisting of channel state estimation, pretreatment, quantization and coding, information coordination and privacy amplification; after the treatment of privacy amplification, a generated bit string can be used as a final shared key for transmitting and receiving parties, for protection the subsequent communication security. According to the method, the problem that a difference exists between channel state sequences collected by the transmitting and receiving parties can be solved, key negotiation and whole key generation efficiency are ensured, and the method can be more widely applied to various complex actual application scenarios, for efficiently ensuring the communication security.

Systems and methodologies are described that facilitate employing downlink precoding based on uplink sounding channel measurement and channel reciprocity in time division duplex or time division multiplex systems. In particular, mechanism are provided that enable downlink precoding in situations where user equipment antenna configuration includes an unequal number of transmit chains and receive chains. A mobile device transmits modulated sounding reference signals on each antenna during a calibration stage. The mobile device then transmits non-modulated sounding reference signals during a normal mode. A base station utilizes the modulated and non-modulated sounding reference signals to restore a downlink channel estimate employed in downlink precoding.

The invention relates to a feedback method for increasing downlink ability in a time division duplex system, which comprises the following steps: step 1, a terminal receives signals of a base station on bidirectional spectrum, which is used for receiving business data or control information; step 2, the terminal sends feedback information to the base station on uplink unidirectional spectrum. The invention can remarkably increase the power control frequency of the downlink in a TDD system and can remarkably reduce the scheduling delay of the TDD system. Furthermore, the invention effectively increases the throughput of the downlink in the TDD system and increases the supporting ability of the TDD system to a high-speed mobile terminal. The invention has the advantages of channel reciprocity and simple terminal structure on one hand, on the other hand has an FDD system with small closed ring control delay and a TDD downlink system which supports high-speed mobile advantage.

The invention discloses a method of obtaining underwater acoustic channel reciprocity by using compressed sensing and relates to underwater acoustic communication. The method is used for obtaining accurate channel parameters from OFDM (Orthogonal Frequency Division Multiplexing) received signals and ensuring the reciprocity of underwater acoustic channels. According to a compressed sensing theory, an OMP algorithm is used for reconstructing time domain impulse noise interference and wide single frequency noise interference, and eliminating the noise interference by observed quantity. For the time domain impulse noise interference, the time domain impulse noise interference is estimated by virtual subcarrier at a receiving end, is reconstructed by the OMP algorithm and is eliminated; the wide single frequency noise extracted at the receiving end has sparsity at a frequency domain, domain conversion is not needed, a measurement matrix is utilized, and the wide single frequency noise interference is reconstructed according to the OMP algorithm and is eliminated. The upper row and the lower row of underwater acoustic channels after the time domain impulse noise interference and the wide single frequency noise interference are eliminated are identical in channel states, namely, the underwater acoustic channels are provided with the reciprocity.

The invention discloses a large-scale antenna array oriented wireless energy information transmission network power control method. The large-scale antenna array oriented wireless energy information transmission network power control method comprises the following steps that firstly upstream channel parameters are estimated on the base station side and are obtained according to channel reciprocity; then, a base station allocates information sending power for each user and calculates pre-encoding vectors to perform downstream energy transmission by means of the method according to the estimated channel parameters; a terminal collects energy and then utilizes the power energy to send the information to the base station through upstream links; finally, the base station calculates receiving vectors according to upstream channel information and accordingly obtains upstream transmitted information of the users. The large-scale antenna array oriented wireless energy information transmission network power control method can be effectively applied to an actual scene, the terminal and rate of a system can be maximized, and meanwhile the minimum rate of the terminal of the system is maximized.

The invention discloses a time varying TDD-MIMO (Time Division Duplex-Multiple Input Multiple Output) channel reciprocity compensating method based on an LS-SVM (Least Square Support Vector Machine); and the channel reciprocities of an uplink and a downlink of a time varying TDD-MIMO communication system are kept by using the method. In the method, by using a base station, channel state information CSI is stored, a training sequence for predicating an LS-SVM channel is generated, a predicating model and parameters are figured out and the CSI of a follow-up downlink sub frame is predicated according to the CSI of an uplink sub frame obtained through channel estimation; and then the follow-up downlink sub frame is pre-encoded by the base station so as to compensate channel reciprocity loss. In the method, because the predicating model is established, the base station can obtain downlink channel state information of the TDD-MIMO system without need of a special feedback link so that the system expense is reduced; meanwhile, the capacity of the system is largely increased by the predicating result and the time varying TDD-MIMO channel reciprocity is compensated.

The invention discloses a time-variant TDD-MIMO communication channel reciprocity compensation method based on channel prediction, mainly aiming at solving the problem of channel reciprocity loss caused by channel time variation in a TDD-MIMO communication system. The method comprises the steps of: using a base station (BS) for carrying out channel estimation on a subframe of an upstream link, and obtaining channel state information of the subframe of the upstream link; then, according to the obtained channel state information of the subframe of the upstream link, predicting the subsequent channel state information of a subframe of a downstream link; according to the predicted channel state information, using the BS for carrying out recoding treatment on the subsequent subframe of the downstream link, and maintaining the channel reciprocity of the TDD-MIMO and the downstream link. The method does not need feedback, and uses the base station to obtain the channel state information of the downstream link in the TDD-MIMO system, thus reducing the cost of the system, being applicable to compensating channel reciprocity loss in the TDD-MIMO system caused by channel time variation.

In a LTE-based wireless communication system, a first user (UE_B) in a first cell (Cell A) may experience significant interference from downlink transmissions in a second cell (Cell B). Interference can be reduced by selecting a precoder for downlink transmission to a second user (UE_A) in the first cell which will result in reduced interference to the first user (UE_B) after the first user (UE_B) is handed-over to the second cell. The uplink/downlink channel reciprocity in TDD systems and the new transmission mode TM9 in LTE Release 10 are exploited to obtain channel information and determine precoding. After handover to the second cell, a resource allocation (RB_B) to the first user (UE_B) is notified to the first cell. In the first cell, the second user (UE_A) receives the same resource allocation and a precoder selected to reduce interference to the first user.

In an existing millimeter-wave MIMO (Multiple Input Multiple Output) system, in order to execute relatively accurate beam forming or spatial multiplexing, commonly, a reference signal needs to be sent on a working frequency band of the system; after estimation, frequency domain, spatial dimension and intensity state information of a channel, which is changed along time, i.e. CSI (Channel State Information); and feedback is carried out. However, the scheme has the problems that a big error is easy to generate for a system which cannot meet channel reciprocity, a certain system cost is brought in, and flexibility of system capacity and resource allocation is influenced. Therefore, the invention discloses a channel measurement and feedback method based on a cognitive radio technology. An idle frequency band is detected near the working frequency band of the system, and according to channel correlation and an idle frequency band available resource condition, channel measurement or feedback of the CSI is flexibly selected to be executed on the idle frequency band or the working frequency band, so that cost on the working frequency band of the system is reduced, and spectral efficiency, reliability and coverage are improved.

The invention belongs to the technical field of wireless communications, and relates to a method for quickly acquiring a plurality of formed beams at the same time in a wireless multiple input multiple outlet (MIMO) communication system by using channel reciprocity of a time division duplex system for iterating, in particular to a quick iteration beam forming method. The quick iteration beam forming method includes the following steps of initializing, conducting LANCZOS iteration, conducting iterative loop control, calculating a transmitting beam forming matrix F and training a receiving beam forming matrix. According to the method, the channel reciprocity of the time division duplex system is adopted, and channel state information does not need to be estimated; meanwhile, through the quick convergence performance and the characteristic that multiple feature vectors can be obtained at the same time of the LANCZOS algorithm, the antenna training speed is greatly increased, and the training cost is lowered.

The invention provides a multi-user safe energy-saving resource allocation method in a mobile edge computing network, which comprises the following steps that: step 1, K users are accessed to a base station in a current time slot, and the base station obtains channel state information of the users through channel training; time division duplex, channel reciprocity and channel compliance with a quasi-static block fading model are set; step 2, energy consumed by local calculation of each user and energy consumed by task unloading of each user are calculated; 3, according to the energy consumed by the local calculation and the energy consumed by unloading the calculation task obtained in the step 2, an optimization problem is constructed, the optimization problem comprises an optimization target and constraint conditions, and the optimization target refers to minimizing the total energy consumption of the system; 4, the optimization problem is solved to obtain the minimum value of the total energy consumption of the system and each corresponding optimization variable when the minimum value is reached; according to the method, the energy consumption is remarkably reduced in the aspectof realizing MEC network security energy-saving task unloading.