摘要:
The transport format (TF) of a signal may be blindly detected from a reduced set of TF hypotheses. In an example embodiment, a method for the blind detection of a TF of a signal includes filtering a set of transport format hypotheses to identify a reduced set of TF hypotheses using one or more filtering schemes. From the reduced set of TF hypotheses, a TF that is associated with an interfering signal is detected. The TF includes a modulation and a spreading factor for the interfering signal. It may also include a number of channelization codes. In an example implementation, when an interfering signal is to be canceled, symbols carried by the signal are detected using the detected TF. Example filtering schemes include filtering based on system design/operation, filtering based on known configuration information, filtering based on an expected level of interference contribution, and so forth.
摘要:
The method an apparatus described herein manages uplink resources to increase spectral efficiency and system capacity. According to one embodiment of the present invention, a base station may be assigned two or more downlink carriers for downlink transmission and two or more corresponding uplink carriers. In a multi-carrier mode, the base station may transmit signals on two or more downlink carriers to the same mobile terminal, and receive signals from the mobile terminal on one of the paired uplink terminals. The uplink carriers can be operated at different interference levels and the uplink traffic can be divided between the available uplink carriers based on the type of traffic and/or data transmission parameters. The mobile terminals may also be allowed to switch between the uplink carriers to improve overall efficiency.
摘要:
In a receive node of a wireless network, an iterative multi-user multi-stage interference cancellation receiver is used. After each stage of interference cancellation, interference characteristics change. An adaptive strategy is used in which after each stage of interference cancellation, impairment covariance is parametrically updated and combining weights of the receiver are adapted to reflect the updated impairment covariance.
摘要:
A receiver is configured to perform symbol detection based on a total frequency domain received signal that comprises contribution from a block of time domain symbols. The receiver comprises electronic circuitry operate to divide the block into plural sub-blocks, and for each sub-block, to jointly detect the symbols of the sub-block while treating symbols of the block which are outside of the sub-block as noise.
摘要:
The quality of a received signal in a non-linear receiver is estimated using a coupling matrix G or Q that describes the interaction of symbols in the received signal with other symbols and/or how the impairment (noise and interference) interacts in the received signal. The coupling matrix is also useful for joint detection. The signal quality estimate may include, e.g., the minimum eigenvalue, and other functions, such as the determinant and trace of the coupling matrix. When G or Q varies with each block, as in CDMA systems employing longcode scrambling, a representative matrix can be used, such as a matrix of RMS values or average magnitudes of real and imaginary components. The signal quality estimate can be expressed as a bit error rate (BER).
摘要:
A receiver comprises plural receive antennas and electronic circuitry. The plural receive antennas are configured to receive, on plural subcarriers transmitted over a radio interface, a frequency domain signal that comprises contribution from a block of time domain symbols. The electronic circuitry is configured or operable to perform symbol detection of time domain symbols comprising the block by performing a multi-stage joint detection procedure comprising plural stages, and thus serves as a detector (40). For a first stage the block is divided into a first number of sub-blocks each having a sub-block first size. For a second stage the block is divided into a second number of sub-blocks each having a sub-block second size, the sub-block second size being greater than the sub-block first size. For each stage a detector (40) formulates frequency domain combining weights and uses the frequency domain combining weights for combining multiple receive versions of each subcarrier to provide candidate symbol combination values for symbols in each sub-block of the respective stage. For the second stage the detector (40) is further configured to use the candidate symbol combination values of the first stage to formulate joint hypotheses to serve as candidates for the joint detection operation of the second stage.
摘要:
Methods and apparatus are disclosed for improving a precoder selection process in a wireless communications system. In a normal precoder selection process, a precoder is selected from a codebook based on channel state information estimated from received reference signals. In between two received reference signals, a subset of precoders is cycled through and each precoder in the subset is iteratively selected for use by a transmitter to precode transmit signals. The subset of precoders may be adaptively modified based on predefined criteria.
摘要:
A CDMA multi-code joint demodulation solution in which impairment suppression and channel matching operations are performed prior to despreading. Embodiments include a linear front end that performs chip-level suppression of signal components that are not included in a subsequent joint demodulation process. The pre-processing stage also carries out metric preparation and provides a vector decision statistic that is processed by a joint demodulation stage to extract per-code soft values for the symbols of interest in the received signal. Both code-specific and code-averaged versions of the linear processing are disclosed, as are several front-end configurations with equivalent performance, but different complexity trade-offs. These new approaches use a block formulation, requiring a set of input chip samples as an input, and perform all operations as matrix-vector multiplications, which is an approach amenable to efficient DSP or hardware implementation.
摘要:
In one aspect, the present invention improves Turbo equalization and/or soft interference cancellation processing in communication receivers by providing an efficient and accurate technique to compute the second moment of a received symbol, e.g., an interfering symbol, as a function of the expected bit values of only those bits in the symbol that are magnitude-controlling bits according to a defined modulation constellation. Advantageously, the expected bit values in at least one embodiment are computed using a LUT that maps bit LLRs to corresponding hyperbolic tangent function values. Further, the expected symbol value is computed as a linear function of terms comprising the expected bit values and the soft symbol variance is efficiently computed from the second moment and the expected symbol value squared. This simplified processing reduces receiver complexity, particularly in the context of modulation constellations having non-constant magnitudes, and thus saves power and/or improves design economics.
摘要:
A system and method in which a base station treats the Channel State Information (CSI) from wireless terminals as only partially-stale, and exploits this partially-stale CSI to predict the current channel from old estimates of the channel. The predicted channel is then used to design a precoder. The base station shapes the transmitted signal with the precoder so as to match it as closely as possible to the current channel. Particular embodiments thus combine the benefits of the stale feedback scheme with precoding to match the channel. Consequently, the signal received at a terminal is better conditioned, thereby providing a greater overall boost in performance of the communication arrangement between the base station and the terminal. The usage of partially-stale CSI can be important for dense networks with a large number of simple terminals.