111 results about "Maximal-ratio combining" patented technology

Certain embodiments of the invention may be found in a method and system for antenna and radio front-end topologies for a system-on-a-chip (SOC) device that combines Bluetooth and IEEE 802.11 b/g WLAN technologies. A single chip radio device that supports WLAN and Bluetooth technologies receives a WLAN signal in a WLAN processing circuitry of the radio front-end and in a Bluetooth processing circuitry of the radio front-end. Signals generated by the WLAN processing circuitry and the Bluetooth processing circuitry from the received WLAN signal may be combined in a diversity combiner that utilizes selection diversity gain combining or maximal ratio combining (MRC). When a generated signal is below a threshold value, the signal may be dropped from the combining operation. A single antenna usage model may be utilized with the single chip radio device front-end topology to support WLAN and Bluetooth communications.

Soft-handoff methods involve receiving an uplink signal from a user equipment at more than one basestation. The uplink signals are processed at each basestation before being backhauled to a common point for use to derive a single signal from the user equipment. One problem with previous types of soft-handoff methods is that relatively complex processing is required at each basestation in order to demodulate and decode the signals. It is also desired to further increase uplink capacity as compared with known types of soft-handoff methods. This is achieved by backhauling signals without carrying out any decoding of the uplink signal at the basestation. The backhauled signals are combined at a common point using maximal ratio combining before being fully demodulated and decoded. As a result capacity is increased and required user equipment transmit power is reduced.

A multiple-input-multiple-output (MIMO) receiving system configured for receiving multiple transmission layers is provided herein. The system includes a plurality of beamformed tunable receiving antennas configured to receive a plurality of transmitted layers; and a control module configured to select for the beamformed antennas a single set of discrete weights for tuning said antennas for all of the transmitted layers so that the weights are selected for optimal performance of said receiving system, wherein said selection is carried out based on an extended Maximal Ratio Combining (MRC) metric or other quality metric measured by the MIMO baseband module, and using said measured metric separately for each beamformed antenna to determine gain or attenuation independently of phase selection.

The present invention relates to use of a smart antenna for a RF reader on a Radio Frequency Identification (RFID) system to significantly increase the operating range of the RFID system. The smart antenna can be an adaptive antenna array. The smart antenna comprises a plurality of antenna elements and, by combining the signals from multiple antenna elements, significantly increases the received signal-to-noise ratio. In a noise limited environment, combining the signals to maximize the received signal-to-noise ratio can be based on the maximal ratio combining (MRC) principle. To achieve the best signal quality, the received signal from each antenna can be phase-shifted such that the resultant signals from all antennas are in phase. In addition, the signal from each antenna can be scaled in amplitude based on the square root of its received signal-to-noise ratio.

The present invention provides a method and system for operating a wireless communication system in which received signals from a plurality of antennas are weighted and combined with a beam forming operation to form an output signal. In an embodiment of the present invention, beamforming operations are performed with maximal ratio combining (MRC) and an interference nulling algorithm (INA). The INA receives an error signal which is 180° out of phase with a combination of the channels for individual antennas, referred to as the SUM channel. The error signal is determined by complex conjugate multiplication of the individual signals and a reference complex signal. The weight amplitude is controlled by weight normalization to provide faster convergence and prevent integrator overflow.

The invention belongs to the technical field of wireless communication and specifically relates to a phase noise compensation and suppression method for a large-scale MIMO system. The method providedby the invention mainly comprises the steps of carrying out maximal-ratio combining on receiving signals of antennas under the condition of assuming that phase noise is zero, thereby obtaining an initial value of a data symbol; carrying out iteration according to the obtained initial value through adoption of a variational Bayesian algorithm, wherein an estimation value of the data symbol is converged to a stable value under the condition that the receiving signal ri is known. The method has the beneficial effects that the data symbol can be judged in a high-order modulation mode within the large-scale MIMO system; and according to a judgment method, the inversion operation of a high-dimensional matrix is avoided in a traditional variational Bayesian inference algorithm, and the inversionoperation of the high-dimensional matrix is converted into the inversion operation of a diagonal matrix, so the system complexity is reduced, and the system performance is improved.

The invention discloses an artificial noise precoding secure transmission method for a full duplex relay system. The method comprises the following steps: an information source adopts an artificial noise precoding scheme to simultaneously broadcast useful signals and artificial noise signals; a relay receives the signals broadcast by the information source and the self-interference at the relay, and a wiretapper receives the signals broadcast by the information source and recoding signals transmitted by the relay; a relay node reduces the influence caused by the self-interference by adopting a self-interference elimination technique; an information sink receives the transmitted signals that are recoded by the relay by adopting a maximal-ratio combining strategy; the signal to interference and noise ratios of the information source to a relay link and the relay to an information sink link are obtained, and the received signal to interference and noise ratios at the information sink and the wiretapper are also calculated; and the instantaneous safety rate of the system is obtained according to the received signal to interference and noise ratios at the information sink and the wiretapper, and an average safety rate is calculated. According to the method disclosed by the invention, the legal channel transmission rate can be increased, and the capacity of wiretap channels can also be effectively reduced.

The present invention provides a method of quantifying a signal to noise ratio (SNR) gap between diversity combining schemes that are operable to process multi-path wireless communications for an arbitrary number of diversity branches. The method determines the gap in a without the need to determine or know the SNR for each individual diversity combining scheme. This involves determining the number of diversity branches associated with the multi-path wireless communication and the receiver used to process the multi-path wireless communication. The SNR gap may then be expressed as the term 10log₁₀L!/L where L is the number of diversity branches.

The invention discloses a full duplex scrambling transmission method in an untrusted relay network, which is applied to a wireless communication system including three nodes of an information source, a relay and a destination node, and the relay is an untrusted relay. The method comprises the following steps: in a first time slot, transmitting information to the relay and the destination node by the information source, and receiving information source information by the destination node and transmitting an interference signal to the relay; in a second time slot, amplifying the signal received in the first time slot by the relay by adopting an amplify-and-forward protocol, after that, forwarding the signal to the destination node; performing self-interference cancellation by the destination node according to estimated channel information, and performing maximal-ratio combining on information received in the first time slot and the second time slot; and calculating the instantaneous security capacity of the system according to the received signal to noise of the relay in the first time slot and the received signal to noise of the destination node in the two time slots. The method of the invention can not only make the information source send the information to the destination node efficiently, but also make the destination node effectively interfere with the relay node to receive useful information, so as to maximize the security capacity of the system.

A COFDM demodulator providing independent DQPSK symbol amplitude and phase equalization provides improved soft-symbol estimates by reducing the possibility of clipping in the differential demodulator, improving the tolerance of the differential demodulator to finite word length effects, correcting for phase drifting between adjacent subcarriers, and improving signal-to-noise ratio (SNR) calculation accuracy for maximal ratio combining applications. Separate acquisition and tracking modes for the amplitude and phase equalizers are provided that handle start-up, reacquisition, and steady-state operation of the demodulator.

The amplify and forward relay method enhances QOS in wireless networks and is based on the switch-and-examine (SEC) and SEC post-selection (SECps) diversity combining techniques where only a single relay out of multiple relays is used to forward the source signal to the destination. The selection process is performed based on a predetermined switching threshold. Maximal-ratio combining (MRC) is used at the destination to combine the signal on the relay path with that on the direct link.

The invention relates to a secure transmission method adopting information source and relay-combined transmitting antenna selection. The method includes the following steps that: in a first time slot, and an information source obtains channel state information from a relay and selects an antenna which makes the received signal to noise of the relay maximum to broadcast confidential signals according to the channel state information, and other three nodes receive signals through adopting maximal-ratio combining; in a second time slot, the relay adaptively decodes a forwarding protocol, when the relay can correctly decode the forwarding protocol, the relay obtains channel state information from an information sink and selects one antenna which makes the received signal to noise of the information sink maximum to forward confidential signals according to the channel state information from the information sink; and when the relay cannot correctly decode the forwarding protocol, the information source obtains the channel state information from the information sink and selects an antenna which makes the received signal to noise of the information sink maximum to retransmit the confidential signals in the first time slot, and the information sink and the relay receive the signals with maximal-ratio combining. According to the method of the invention, transmitting antenna selection technology is adopted to maximize the received signal to noise ratio of the relay or the information sink, and the received signal to noise ratio of an eavesdropper can be decreased, and low complexity and high security can be achieved.

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 a method and device for frequency domain equalization detection. The method comprises the steps that a time domain signal interference noise ratio (SINR) and a noise interference covariance matrix Re_pilot of a pilot frequency subcarrier are calculated; the noise interference covariance matrix Re_pilot of the pilot frequency subcarrier is utilized for calculating a noise interference ratio (NIR); the time domain SINR and the NIR are utilized for determining the adoption of an interference rejection combining (IRC) detection mode or a maximal ratio combining (MRC) detection mode to conduct the frequency domain equalization detection. According to the method and device for the frequency domain equalization detection, the frequency domain equalization detection is conducted in the mode that the MRC detection mode or the IRC detection mode is selected in a self-adaptive pattern, therefore, when interference plays a leading role in receiving signals, the interference and noise can be distinguished and processed, and the detection performance can be fully guaranteed; when the interference does not play a leading role in receiving the signals, the situation that computational accuracy is lowered due to the introduction of channel estimation errors cannot occur, and therefore the detection performance can be fully guaranteed.

The invention provides a dual-medium hybrid fading communication system performance analysis method based on an AF (Amplify and Forward) protocol, and belongs to the technical field of dual-medium cooperative communications. The method comprises the following steps: establishing a Moment Generating Function (MGF) model that satisfies the signal-to-noise ratio of a wireless link in the Nakagami distribution; establishing an MGF model that satisfies the signal-to-noise ratio of a power line link in the logarithmic normal distribution; according to the two MGF models respectively established in the above steps, determining an MGF model of the total signal-to-noise ratio of a system under Maximal Ratio Combining (MRC); and determining the bit error rate and outage probability of the system according to the system total signal-to-noise ratio MGF model. According to the dual-medium hybrid fading communication system performance analysis method based on the AF protocol provided by the invention, the system performance calculation complexity is simplified, optimal distribution parameters of system performance can be obtained, and a theoretical expression of the bit error rate and the outage probability of the system can be calculated approximately.

The invention discloses a transmitting light path selecting method for combined diversity reception in MIMO (Multiple-input and Multiple-Output)free space optical communication, and belongs to the technical field of MIMO free space optical communication. The transmitting light path selecting method comprises the following steps of: carrying out comparison on the light intensity gain after the gains from each laser to Nr detectors and the like are combined to obtain a serial number of the laser with maximum light intensity gain value, and then feedbacking the serial number of the laser to a light path selector at a transmitting end by a low-speed feedback channel so as to enable the transmitting end to select and activate the optimal laser for transmitting light signals. The method disclosed by the invention has the advantages that the system performances of the MIMO free space optical communication modulated on basis of OOK (On-Off Keying) are obviously improved, and compared with maximal-ratio combining reception, the complexity for realizing the method of united equal-gain combining reception, adopted by the invention, on hardware can be reduced.

The invention is applicable to the field of wireless communication, and provides a search method for the best communication location of multiple mobile relays. The method comprises the following steps: (A) mobile relays receive a training sequence sent by a source end in any position of a fixed orbit, and transmit the training sequence to a destination end; (B) the destination end receives independent fading signals from the mobile relays and performs maximal-ratio combining, and then, generates single-bit information according to the combining result in each time slot and feeds the single-bit information back to all the mobile relays through broadcasting; and (C) the mobile relays record the current location information, perform calculation according to the single-bit information and move according to the calculation result, the method returns to step A, and finally, the best relay communication position is determined. According to the search method provided by the invention, an airborne single antenna is used, there is neither need to rely on GPS nor need to know the location information of a ground communication unit, and the mobile relays can find the best relay communication location within a given movement trajectory range only by use of the bit information fed-back by the destination end.

The invention discloses a multi-channel signal synchronization and diversity combining device and method. The method comprises the following steps: receiving multi-channel diversity signals, and calculating the signal-to-noise ratio (SNR) of the signals of each channel according to the multi-channel diversity signals; selecting the signals of any channel as reference signals, and carrying out orthogonal down-conversion and low-pass filtering on the signals of each channel; carrying out inner ring phase discrimination and loop filtering on the reference signals and the signals of the other channels; respectively carrying out maximal-ratio combining on all same-phase branches and orthogonal branches that are obtained through the low-pass filtering; carrying out outer ring phase discrimination and loop filtering on maximal-ratio combining results; completing pre-combining same-frequency and same-phase adjustments of the multi-channel signals jointly through a plurality of differential mode rings and an overall common mode ring; and completing calculation of weights of the signals of each channel during the combining through SNR estimations, so that the maximal-ratio combining is completed. The method has the advantages that the implementation is easy; and a larger combining gain can be provided, so that the information transmission quality is improved.

The invention discloses a self-adaption relay communication method based on ladder modulation. The method comprises the steps: (1) obtaining basic layer data and strengthening layer data; (2) adding cyclic redundancy check (CRC) codes; (3) conducting convolution and coding; (4) obtaining a sending data matrix; (5) confirming a star map; (6) modulating sending data; (7) sending a relay noise signal; (8) conducting self-adaption choosing processing; (9) sending a direct route signal and a relay route signal; (10) combining signals; (11) conducting demodulation, convolution and decoding; and (12) removing the check codes. Ladder modulation, relay node self-adaption choosing processing and a maximal-ratio combining method are adopted by the self-adaption relay communication method to complete self-adaption relay communications based on the ladder modulation, according to different error code conditions, self-adaption choosing processing of relay nodes is allowed, error code rate of data of various routes can achieved independent controlling, the basic layer data and the strengthening layer data are fully and reasonably utilized, and error code performance of a whole system is improved.

The invention discloses a full-duplex opportunistic relaying protocol self-adaptation switching security transmission scheme. The scheme is applied to a system including an information source, a relay, an information sink and an eavesdropper. According to the scheme, information is transmitted to the relay through the information source, the relay can perform transmission by selecting an antenna which can maximize the received signal to noise ratio of the information sink, maximal-ratio combining is performed by means of other antennas, and information of the information source is received; in the process, it is supposed that the relay can obtain channel state information of the information sink and the eavesdropper, the average security speed of the system is estimated by means of the information, and transmission is performed by selecting the best relay protocol from an amplifying-forwarding protocol and a decoding-forwarding protocol. The system security speed is a comparison condition, the two main protocols are automatically switched, and the evaluation security speed of the system can be increased and the evaluation security performance of the system can be improved by selecting the best relay protocol according to scenes in a self-adaptation mode.