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:
A rate adaptive transmission scheme for MIMO systems, which can transmit a variable number of data symbol streams, provide transmit diversity for each data symbol stream, and fully utilize the total transmit power of the system and the full power of each antenna. In one method, at least one data symbol stream is received for transmission from a plurality of antennas. Each data symbol stream is scaled with a respective weight corresponding to the amount of transmit power allocated to that stream. The scaled data symbol stream(s) are multiplied with a transmit basis matrix to provide a plurality of transmit symbol streams for the plurality of antennas. The transmit basis matrix (e.g., a Walsh-Hadamard matrix or a DFT matrix) is defined such that each data symbol stream is transmitted from all antennas and each transmit symbol stream is transmitted at (or near) the full power for the associated antenna.
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:
A transmitter generates multiple composite pilots with a training matrix and a gain matrix. Each composite pilot includes multiple training pilots generated with multiple columns of the training matrix and scaled with multiple gain elements in a column of the gain matrix. The transmitter transmits each composite pilot via multiple transmit antennas. A MISO receiver obtains received symbols for the multiple composite pilots and derives an estimate of a composite MISO channel. For OFDM, the MISO receiver derives an initial impulse response estimate for each composite pilot, filters the initial impulse response estimates for all composite pilots, and derives a frequency response estimate for the composite MISO channel. A MIMO receiver obtains and processes received symbols for the multiple composite pilots based on the training and gain matrices and derives channel estimates for individual SISO channels between the multiple transmit antennas and multiple receive antennas.
摘要:
Systems and methodologies are described that facilitate providing auxiliary multiple-input, multiple-output (MIMO) pilot signals to MIMO user devices in a wireless communication environment. According to some aspects, a portion of data transmission power may be reallocated for auxiliary MIMO pilot transmission during a data segment in a time slot, in order to permit a MIMO user device to perform CQI and rank prediction. Additionally or alternatively, non-MIMO pilot transmission power may be reallocated in a pilot segment in the time slot for transmission of an auxiliary MIMO pilot signal to permit the MIMO user device to demodulate data transmitted in data segments of the time slot. MIMO pilot signals may additionally be time-division multiplexed within or across time slots and may be transmitted over available Walsh codes in data and control segments.
摘要:
Systems and methodologies are described that facilitate reducing rank (e.g., of a user device) as a number of transmissions there from increases. Such rank step-down can improve interference resistance and facilitate maintaining code rate despite transmission propagation. Additionally, rank step-down information can be encoded along with CQI information to generate a 5-bit CQI signal that can facilitate updating a user's rank upon each CQI transmission (e.g., approximately every 5 ms). The described systems and/or methods can be employed in a single code word (SCW) wireless communication environment with a hybrid automatic request (HARQ) protocol.
摘要:
Systems and methodologies are described that facilitate providing auxiliary multiple-input, multiple-output (MIMO) pilot signals to MIMO user devices in a wireless communication environment. According to some aspects, a portion of data transmission power may be reallocated for auxiliary MIMO pilot transmission during a data segment in a time slot, in order to permit a MIMO user device to perform CQI and rank prediction. Additionally or alternatively, non-MIMO pilot transmission power may be reallocated in a pilot segment in the time slot for transmission of an auxiliary MIMO pilot signal to permit the MIMO user device to demodulate data transmitted in data segments of the time slot. MIMO pilot signals may additionally be time-division multiplexed within or across time slots and may be transmitted over available Walsh codes in data and control segments.
摘要:
A rate adaptive transmission scheme for MIMO systems, which can transmit a variable number of data symbol streams, provide transmit diversity for each data symbol stream, and fully utilize the total transmit power of the system and the full power of each antenna. In one method, at least one data symbol stream is received for transmission from a plurality of antennas. Each data symbol stream is scaled with a respective weight corresponding to the amount of transmit power allocated to that stream. The scaled data symbol stream(s) are multiplied with a transmit basis matrix to provide a plurality of transmit symbol streams for the plurality of antennas. The transmit basis matrix (e.g., a Walsh-Hadamard matrix or a DFT matrix) is defined such that each data symbol stream is transmitted from all antennas and each transmit symbol stream is transmitted at (or near) the full power for the associated antenna.
摘要:
A transmitter generates multiple composite pilots with a training matrix and a gain matrix. Each composite pilot includes multiple training pilots generated with multiple columns of the training matrix and scaled with multiple gain elements in a column of the gain matrix. The transmitter transmits each composite pilot via multiple transmit antennas. A MISO receiver obtains received symbols for the multiple composite pilots and derives an estimate of a composite MISO channel. For OFDM, the MISO receiver derives an initial impulse response estimate for each composite pilot, filters the initial impulse response estimates for all composite pilots, and derives a frequency response estimate for the composite MISO channel. A MIMO receiver obtains and processes received symbols for the multiple composite pilots based on the training and gain matrices and derives channel estimates for individual SISO channels between the multiple transmit antennas and multiple receive antennas.
摘要:
Systems and methodologies are described that facilitate providing high reuse for transmitting reference signals, such as positioning reference signals (PRS) and cell-specific reference signals (CRS), to improve hearability thereof for applications such as trilateration and/or the like. In particular, PRSs can be transmitted in designated or selected positioning subframes. Resource elements within the positioning subframe can be selected for transmitting the PRSs and can avoid conflict with designated control regions, resource elements used for transmitting cell-specific reference signals, and/or the like. Resource elements for transmitting PRSs can be selected according to a planned or pseudo-random reuse scheme. In addition, a transmit diversity scheme can be applied to the PRSs to minimize impact of introducing the PRSs to legacy devices. Moreover, portions of a subframe not designated for PRS transmission can be utilized for user plane data transmission.