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.
摘要:
Techniques for rank adaptation and multiple-stream reverse link communications in a wireless access network are disclosed. A remote unit transmits one or more reverse link data streams using separate identifiers to a base station. The number of reverse link data streams may be determined according to feedback from the base station or it may be determined by testing one or more multiple-antenna transmit hypotheses. The base station may estimate channel conditions using information obtained from the one or more reverse link data streams and may determine a spatial rank of the communication channel. The remote unit may perform separate error control and power control processes for each reverse link data stream in cooperation with the base station.
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:
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.
摘要:
Space division multiple access channelization is provided that includes scheduling transmission for two or more terminals and utilizing different code offsets that correspond to different sub-trees. The transmissions can be scheduled on overlapping frequency resources for overlapping time periods on different spatial resources. The pilot code offsets provide different pilot signatures so that the pilot transmissions do not overlap. The overlapping frequency resources can partially overlap or completely overlap.
摘要:
Techniques are provided to support successive interference cancellation (SIC) receiver processing with selection diversity whereby each of NT transmit antennas may be turned on or off. One symbol stream may be transmitted from each transmit antenna. A SIC receiver recovers the transmitted symbol streams in a specific order. Up to NT! orderings are evaluated. For each ordering, NT post-detection SNRs are obtained for NT transmit antennas and used to determine NT data rates, where the data rate is zero if the post-detection SNR is worse than a minimum required SNR. An overall data rate is computed for each ordering based on the NT data rates. The ordering with the highest overall data rate is selected for use. Up to NT symbol streams are processed at the data rates for the selected ordering and transmitted. The transmitted symbol streams are recovered in accordance with the selected ordering.
摘要:
Techniques to estimate the frequency response of a wireless channel in an OFDM system. In one method, an initial estimate of the frequency response of the wireless channel is obtained for a first group of subbands based on a pilot transmission received via the subbands in the first group. An estimate of the impulse response of the wireless channel is then derived based on the initial frequency response estimate. An enhanced estimate of the frequency response of the wireless channel is then derived for a second group of subbands based on the impulse response estimate. The first and second groups may each include all or only a subset of the usable subbands. Subband multiplexing may be used to allow simultaneous pilot transmissions by multiple terminals on their associated groups of subbands.
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 method and apparatus for broadcast multicast service in an ultra mobile broadband network is provided. An apparatus is provided which is operable in a wireless communication system to provide a means for mapping broadcast flows to a broadcast multicast logical channel and transmitting the broadcast multicast logic channel on an aggregation of broadcast physical channels, where each of the aggregation of the broadcast physical channels is uniquely characterized. Radio configurations to support the ultra mobile broadband network are also provided.
摘要:
Spatial pilot to support MIMO receivers in a multi-antenna and multi-layer transmission communication system. A first layer pilot for a single layer transmission is repeated across subbands in a first OFDM symbol and the first layer pilot is also repeated offset from the first OFDM symbol in an adjacent second OFDM symbol. Additional transmission layers may also be transmitted each include a separate pilot generated and repeated in the first symbol and repeated offset form the separate pilot in an adjacent second symbol. The first and second OFDM symbols are then transmitted and received to characterize the receive channels.