摘要:
Methods and apparatus for multiple-input multiple-output (MIMO) transmissions are disclosed. A base station may precode wireless transmit/receive unit (WTRU)-specific reference signals and data that are transmitted to a WTRU using a randomly selected precoder. The precoder may be selected based on a predefined precoder selection sequence or by the base station. A different precoder may be applied to different resource blocks (RBs). In addition, a large delay cyclic delay diversity (CDD) or discrete Fourier transform (DFT) spreading may be applied on the WTRU-specific reference signals and the data. For heterogeneous deployed antennas, spatial diversity gain is achieved by dynamically scheduling resources between transmission points. A hopping scheme may be applied across the transmission points as the resources are dynamically partitioned between the transmission points. A different randomly selected precoder may be applied to each RB transmitted from a different transmission point.
摘要:
Methods and apparatus for multiple-input multiple-output (MIMO) transmissions are disclosed. A base station may precode wireless transmit/receive unit (WTRU)-specific reference signals and data that are transmitted to a WTRU using a randomly selected precoder. The precoder may be selected based on a predefined precoder selection sequence or by the base station. A different precoder may be applied to different resource blocks (RBs). In addition, a large delay cyclic delay diversity (CDD) or discrete Fourier transform (DFT) spreading may be applied on the WTRU-specific reference signals and the data. For heterogeneous deployed antennas, spatial diversity gain is achieved by dynamically scheduling resources between transmission points. A hopping scheme may be applied across the transmission points as the resources are dynamically partitioned between the transmission points. A different randomly selected precoder may be applied to each RB transmitted from a different transmission point.
摘要:
A method and apparatus for using demodulation reference signal (DM-RS) based channel state information (CSI) feedback in Orthogonal Frequency Division Multiplexing—multiple-input multiple-output (OFDM-MIMO) systems is disclosed. The wireless transmit/receive unit (WTRU) receives one or more resource blocks from a base station, wherein the resource blocks (RBs) include demodulating reference signals (DM-RS) and precoder information. The precoder information is sent unicast or broadcasted over a common control channel. The WTRU estimates an effective channel estimate based on the DM-RS, derives an unprecoded channel based on the effective channel and the precoder information, generates CSI feedback based on the unprecoded channel, and transmits the CSI feedback to the base station. Alternatively, the WTRU estimates an effective channel estimate based on the DM-RS, quantizes the effective channel estimate and transmits the CSI feedback to the base station.
摘要:
An iterative nonlinear preceding method based on, for example. Tomlinson-Harashima Preceding (THP) may be implemented in a MU-MIMO system to alleviate the performance degradation due to mismatches between actual Channel State Information (CSI) and impaired CSI available at a transmitter. In such a method, the effective channel may be fed back rather than a nonprecoded channel for a relay backhaul channel such that the iterative precoding and effective channel feedback may reduce the sensitivity to quantization errors and improve spectrum usage efficiency. Additionally, a Channel Quality Indicator (CQI) may be used to estimate a signal-to-interference-plus-noise (SINK) ratio based on quantization errors to accurately derive the effective channel quality of the receiver.
摘要:
Methods and apparatus are described for compressing channel state information (CSI) in time-domain based on path location information for CSI feedback. Downlink (DL) CSI is compressed in the time domain and fed back by not sending the multipath location information, or sending at a very low rate. In one method, a wireless transmit/receive unit (WTRU) selects the strongest multipath components based on channel characteristics. The multipath components are quantized in the time domain via direct or vector based quantization. The base station reconstructs a channel impulse response from the fed back quantized multipath components and applies same to precoding processing. In another method, the WTRU feeds back information associated with a narrowband portion(s) of a system spectrum. The selected narrowband portion(s) have sufficient density over time to allow good precoding per subband or across the system spectrum. Short term feedback may be augmented with long term channel information.
摘要:
Systems and methods for channel quality indicator (CQI) feedback may be disclosed. At a current transmission time interval, precoder and/or modulation information that may be used at or associated with a future transmission time interval may be determined. As such, at a current transmission time interval, precoder and/or modulation information that may be used to select a modulation or coding scheme (MCS) and/or schedule transmission at a future transmission time interval may be predicted in the current transmission time interval. The precoder and/or modulation information may be broadcast and received such that the information may be used to estimate a channel quality indicator (CQI) at the current transmission time interval. The estimated CQI may be used to select a modulation and coding scheme (MCS), schedule transmissions, and the like.
摘要:
Systems, methods, and instrumentalities are disclosed for a user equipment (UE) to provide feedback in a multi-site scheduling system (e.g., a system where multiple entities may schedule and/or send data to the UE). For example, the UE may receive a first data from a first network entity and a second data from a second network entity. A network entity may include entities that transmit data and/or control information to the UE, e.g., an eNodeB (eNB). The UE may generate feedback relating to received data, such as ACK/NACK information or channel state information (CSI). The UE may send a first feedback relating to the first data in a first subframe and a second feedback relating to the second data in a second subframe.
摘要:
An iterative nonlinear preceding method based on, for example. Tomlinson-Harashima Preceding (THP) may be implemented in a MU-MIMO system to alleviate the performance degradation due to mismatches between actual Channel State Information (CSI) and impaired CSI available at a transmitter. In such a method, the effective channel may be fed back rather than a nonprecoded channel for a relay backhaul channel such that the iterative precoding and effective channel feedback may reduce the sensitivity to quantization errors and improve spectrum usage efficiency. Additionally, a Channel Quality Indicator (CQI) may be used to estimate a signal-to-interference-plus-noise (SINK) ratio based on quantization errors to accurately derive the effective channel quality of the receiver.
摘要:
Systems, methods, and instrumentalities are disclosed for a user equipment (UE) to provide feedback in a multi-site scheduling system (e.g., a system where multiple entities may schedule and/or send data to the UE). For example, the UE may receive a first data from a first network entity and a second data from a second network entity. A network entity may include entities that transmit data and/or control information to the UE, e.g., an eNodeB (eNB). The UE may generate feedback relating to received data, such as ACK/NACK information or channel state information (CSI). The UE may send a first feedback relating to the first data in a first subframe and a second feedback relating to the second data in a second subframe.
摘要:
Feedback information for multiple serving cells are transmitted on high speed dedicated physical control channel (HS-DPCCH). A slot format for transmitting feedback information is determined based on the number of configured secondary serving cells and whether multiple input multiple-output (MIMO) is configured in the serving cells. Spreading factor is reduced to 128 when two secondary serving cells are configured and MIMO is configured in at least one of the two configured secondary serving cells, or when three secondary serving cells are configured. The serving cells are grouped into feedback groups, each feedback group having one or more serving cells. Channel coding may be applied to feedback information for the feedback groups. The resulting encoded feedback information for the feedback groups is concatenated to form composite feedback information.