摘要:
A method codes multiple data streams in multiple-input, multiple-output communications systems. In a transmitter, an input bitstream is encoded as codewords b in multiple layers. Each layer is modulated. A quasi-block diagonal, low-density parity-check code is applied to each layer, the quasi-block diagonal, parity-check code being a matrix H, the matrix H including one row of blocks for each subcode, and one row of blocks for each layer such that Hb=0 for any valid codeword. The layers are then forwarded to transmit antennas as a transmitted signal x.
摘要:
A method estimates a channel impulse response in an ultra wide bandwidth (UWB) system. Multiple training sequences modulated at a chip rate are received. Each training sequence is sampled by parallel with multiple correlators at sampling rate substantially slower than the chip rate to obtain a samples over a time interval of the impulse response at a resolution substantially equal to the chip rate, and then estimating the channel impulse response from these samples.
摘要:
A method minimizes a rate for feeding back channel state information from a receiver to a transmitter in a multi-input, multi-output communications systems. A temporal autocorrelation function of the channel between the transmitter and the receiver is determined. A spatial covariance information is estimated of the channel. Then, the minimum rate for feeding back channel state information from the receiver to the transmitter is based on actual channel state information and the estimated spatial covariance information and the temporal autocorrelation function.
摘要:
A method suppresses interference in a time-frequency hopped, ultra wide bandwidth system. Signals corresponding to a transmitted symbol are received. The received signals are frequency demodulated, and a coefficient vector w that minimizes a cost function C ( w n ) = 1 ∑ k λ n - k ∑ k λ n - k w n H x k - c k 2 , is estimated, where λ is a weighting factor between 0, x is a vector representing the received signals, H is a frequency response of a channel used to transmit the symbol, and c is a known training symbol. A coefficient vector, ŵn={circumflex over (R)}n−1{circumflex over (d)}n, is determined, where a correlation matrix for the received signals is R ^ n = 1 ∑ k λ n - k ∑ k λ n - k x k x k H , and an estimate of a crosscorrelation is d ^ n = 1 ∑ k λ n - k ∑ k λ n - k x k c k * . The received signals are then combined according to c ^ n = 1 C ( w ^ n ) w ^ n H x n = 1 1 - w ^ n H d ^ n w ^ n H x n .
摘要:
A method transmits and receives signals in a cooperative, multi-user, multi-input, multi-output network. The network includes base stations (BSs) and mobile stations (MSs). Each BS has at least two antennas, and each MS has at least one antenna. At a first base station and a second base station using linear pre-coding matrices, a plurality of data streams are jointly pre-coded to produce first signals and second signals. The first signals are transmitted synchronously from the first BS and the second BS to a first MS, and the second signals are transmitted synchronously from the first BS and the second BS to a second MS, and in the first signal and the second signal are asynchronous with respect each other.
摘要:
A method eliminates spectral lines in a time hopping ultra wide bandwidth signal. First, a train of pulses is generated from input symbols. The pulses are then modulated in time according to symbols. The modulation can use pulse position modulation and time hopping. A polarity of the pulses is inverted randomly before transmitting the pulses as an ultra wide bandwidth signal. By randomly inverting the polarity of the pulses spectral lines in the ultra wide bandwidth signal are eliminated.
摘要:
A method increases transmit diversity gain in a wireless communication system. In the wireless network, a transmitter has multiple antennas and a receiver has one antenna. A phase of each of received signal is measured. One signal is selected as a reference signal. For each other signal, a phase, with respect to the phase of the reference signal, is measured independently to determine feedback information indicating a required rotation of each other signal so that a phase of each other rotated signal is within an identical quadrant as the phase of the reference signal. The feedback information for each other signal is sent to the transmitter. In the transmitter, each other signal is phase rotated according to the corresponding feedback information before the signal is transmitting to the receiver.
摘要:
A method for antenna subset selection by joint processing in RF and baseband in a multi-antenna systems. Lt input data streams are generated in a transmitter for either diversity transmission or multiplexing transmission. These streams are modulated to RF signals. These signals are switched to the t branches associated with the t transmit antennas, and a phase-shift transformation is applied to the RF signals by a t×t matrix multiplication operator Φ1, whose output are t≧Lt RF signals. These signals are transmitted over a channel by t antennas. The transmitted signals are received by r antennas in a receiver. A phase-shift transformation is applied to the r RF signals by a r×r matrix multiplication operator Φ2. Lr branches of these phase shifted streams are demodulated and further processed in baseband to recover the input data streams.
摘要:
A method analyzes a set of signal acquired from a physical system. A set of parameters characterizing the set of signals is measured. The parameters can include the mean and the variance of the power of the signal, and a Rician factor. A first point and a second point of a moment generating function for a combination of the set of signals are evaluated according to the set of parameters to obtain a first sample and a second sample, respectively. First and second equations are defined. The equations respectively have an approximation of a moment generation function of a lognormal random variable representing the combination of the set of signals, at the first point and the second point, on the left side, and the first and second sample on the right side. The two equations are solved to obtain a mean and a variance of the lognormal random variable representing a distribution of the combination of the set of the signals.
摘要:
A method is presented for processing signals of a multiple-input, multiple-output communications system in the RF domain. The system includes multiple transmit antennas and multiple receive antennas connected by a wireless channel. A matrix M is generated based on long-term characteristics of the wireless channel. The matrix M is multiplied times input RF signals to obtain output RF signals. The matrix can be generated in a transmitter, a receiver, or both.