摘要:
Apparatuses and methodologies are described that enhance performance in a wireless communication system using beamforming transmissions. According to one aspect, a set of transmit beams are defined that simultaneously provides for space division multiplexing, multiple-input multiple output (MIMO transmission and opportunistic beamforming. The addition of a wide beam guarantees a minimum acceptable performance for all user devices.
摘要:
Apparatuses and methodologies are described that enhance performance in a wireless communication system using beamforming transmissions. According to one aspect, the channel quality is monitored. Channel quality indicators can be used to select a scheduling technique, such as space division multiplexing (SDM), multiple-input multiple output (MIMO) transmission and opportunistic beamforming for one or more user devices. In addition, the CQI can be used to determine the appropriate beam assignment or to update the beam pattern.
摘要:
Systems and methodologies are described that facilitate improved pilot information to MIMO user devices without increasing interference of SISO user devices in a wireless communication environment. A data communication signal can be generated and transmitted at a first power level, and a continuous pilot waveform comprising pilot information related to the data signal can be generated and sent at a second power level below the first transmission power level. Alternatively, a discontinuous pilot waveform can be generated so that it does not overlap with pilot segments in the first waveform, and can be transmitted at the first power level without interfering with the first waveform as received by a SISO user device. A MIMO user device can receive both waveforms, and can employ the pilot waveform to better estimate a MIMO channel for the first waveform.
摘要:
Techniques to enhance the performance in a wireless communication system using segments called subbands and using precoding are shown. According to one aspect, the bandwidth for transmission to an access terminal is constrained to a preferred bandwidth which is less than the bandwidth available for transmission to an access terminal and precoding information related to the subcarriers within the constrained bandwidth is provided to a transmitter. The precoding information related to the subcarriers within a constrained bandwidth provides feedback about the forward link channel properties relative to different subbands and may be fed back on a channel associated with the bandwidth.
摘要:
Efficient pilot transmission schemes for multi-antenna communication systems are described. In general, MISO receivers prefer a pilot transmitted in one spatial direction, and MIMO receivers typically require a pilot transmitted in different spatial directions. In one pilot transmission scheme, a first set of T scaled pilot symbols is generated with a first training vector and transmitted (e.g., continuously) from T transmit antennas, where T>1. If MIMO receiver(s) are to be supported by the system, then at least T−1 additional sets of T scaled pilot symbols are generated with at least T−1 additional training vectors and transmitted from the T transmit antennas. The training vectors are for different (e.g., orthogonal) spatial directions. Each MISO receiver can estimate its MISO channel based on the first set of scaled pilot symbols. Each MIMO receiver can estimate its MIMO channel based on the first and additional sets of scaled pilot symbols.
摘要:
Accordingly, a method and apparatus are provided wherein a receiver system selects a pre-coding matrix, comprising eigen-beamforming weights, to use and provides rank value and matrix index associated with the selected matrix to the transmitter system. The transmitter system upon receiving the rank value and matrix index, determine if the matrix associated with the matrix index provided by the receiver system can be used. If not, them transmitter system selects another matrix for determining eigen-beamforming weights.
摘要:
Embodiments are described in connection with enhancing performance in a wireless communication system using codebook technology. According to an embodiment is a method for enhancing performance in a wireless communication environment. The method can include receiving a user preference for a transmission mode, associating the user preference with an entry or entries in a codebook, and assigning the user to a transmission mode corresponding to the entry or entries. The transmission mode can be one of a preceding, space division multiple access (SDMA), SDMA preceding, multiple input multiple output (MIMO), MIMO preceding, MIMO-SDMA and a diversity. Each entry can correspond to a transmission mode.
摘要:
Each transmitter is assigned a time-only pilot code, a frequency-only pilot code, or a time-frequency pilot code to use for pilot transmission. The pilot codes may be pseudo-random, orthogonal, and/or cyclic-shift codes. To obtain a channel estimate for a transmitter using a time-frequency pilot code composed of a time-only code and a frequency-only code, a receiver multiplies a set of received symbols for each symbol period with a set of code values for the frequency-only code to obtain a set of detected symbols and performs an IDFT on the set of detected symbols to obtain an initial impulse response estimate. The receiver performs code matching on multiple initial impulse response estimates derived for multiple symbol periods with the time-only code to obtain a final impulse response estimate for the desired transmitter. The receiver retains the first L channel taps and zeroes out remaining channel taps, where L is the expected channel length.
摘要:
Techniques to facilitate estimating the frequency response of a wireless channel in an OFDM system are provided. The method and systems allow for combining signal information across multiple communication channels at one or more channel tap delays in order to determine appropriate taps for channel information.
摘要:
Transmission schemes that can flexibly achieve the desired spatial multiplexing order, spatial diversity order, and channel estimation overhead order are described. For data transmission, the assigned subcarriers and spatial multiplexing order (M) for a receiver are determined, where M≧1. For each assigned subcarrier, M virtual antennas are selected from among V virtual antennas formed with V columns of an orthonormal matrix, where V≧M. V may be selected to achieve the desired spatial diversity order and channel estimation overhead order. Output symbols are mapped to the M virtual antennas selected for each assigned subcarrier by applying the orthonormal matrix. Pilot symbols are also mapped to the V virtual antennas. The mapped symbols are provided for transmission from T transmit antennas, where T≧V. Transmission symbols are generated for the mapped symbols, e.g., based on OFDM or SC-FDMA. Different cyclic delays may be applied for the T transmit antennas to improve diversity.