Abstract: A method of performing downlink multiuser superposition transmission (MUST) with enhanced channel state information (CSI) feedback is proposed. When a user equipment (UE) reports CQI/SINR feedback for RI=RANK-2, the UE also reports a single beam CQI/SINR feedback for RI=RANK1. As a result, the scheduling base station can calculate the actual SINRs based on different MUST scenarios and thereby determining appropriate modulation and coding scheme (MCS) for the UE. Furthermore, if the granularity of the CQI table cannot reflect the high values of the single beam SINR, then a predefined scaling factor (0<?<1) known to both the base station and the UE may be applied.

Abstract: When the codeword level interference cancellation (CW-IC) is used at the receiver in conjunction with the superposition coding scheme at the transmitter, it is helpful if the soft buffer at the receiver is reserved not only for the desired transport blocks (TBs) but also for the interfering TBs handled by the CW-IC. In so doing, the soft channel bits of interfering TBs at multiple (re)transmissions can be combined to enhance the success rate of data decoding. A soft buffer partition method for the soft channel bits of the desired and interfering TBs in the superposition coding scheme is proposed. The proposed method has a full flexibility in adjusting the soft buffer sizes for the desired and interfering TBs.

Abstract: Methods for rate matching with soft buffer size setting at the transmitter and soft channel bits storage at the receiver for superposition coding are proposed. In the superposition coding scheme, a transport block intended to one UE needs to be decoded by another UE's receiver. However, the soft buffer sizes per code block of the two receivers may not be the same since the size depends on the UE category. The base station can signal the soft buffer size used at the transmitter for rate matching to the UEs for superposition decoding. A UE stores information bits associated with an interfering signal in its soft buffers in accordance with the soft buffer size used at the transmitter for rate matching. As a result, the UE can decode and subtract the interfering signal from the desired signal for superposition coding.

Abstract: When the codeword level interference cancellation (CW-IC) is used at the receiver in conjunction with the superposition coding scheme at the transmitter, in order to guarantee the success of signal reception, restrictions of scheduling decisions in resource allocation of superposed transport blocks may occur. A method to mitigate the scheduling restrictions is proposed. For a low-geometry UE in NOMA operation, one sub-band is used as the basic scheduling unit. As a result, data in resource blocks scheduled for NOMA operation and data in resource blocks scheduled for other non-NOMA operation correspond to different transport blocks. Therefore, a high-geometric UE only needs to decode the data scheduled for NOMA. The base station does not need to impose additional scheduling restrictions and signaling overhead.

Abstract: A method for a receiver to cancel or suppress co-channel interference with network assistance is provided. The method comprises deriving a first set of parameters related to interfering signals in a mobile communication network; receiving a second set of parameters related to the interfering signals from the network; and cancelling the contribution of interfering signals from the received signal based on the combination of the first set and second set of parameters. In one embodiment, scrambling rules and resource block allocation information are signaled to the victim UE to facilitate Codeword-Level Interference Cancellation (CWIC). While the scrambling rule for control channel is based on UE-specific identity, the scrambling rule for data channel is based on cell-specific identity or other network-configurable identity to facilitate CWIC. In addition, RA-allocation information are signaled to the victim UE in an efficient way.

Abstract: A method of interference cancellation is proposed. A serving base station transmits a first configuration information to a UE, the first configuration information is related to a desired signal of a data transmission from a serving cell to the UE. The serving base station determines a second configuration information related to an interference signal of a data transmission from a neighboring cell to the UE. The second configuration information comprises a resource allocation type and a basic resource allocation unit of the interference signal. The serving base station transmits the second configuration information to the UE such that the UE can cancel the data transmission from the neighboring cell.

Abstract: A method is proposed to enable a UE performing codeword level interference cancellation (CW-IC) to know whether an interfering transport block (TB) is a new transmission or retransmission. With this knowledge, the UE knows whether the soft channel bits stored in a soft buffer are to be discarded or combined with the soft channel bits newly obtained.

Abstract: A method of interference cancellation is proposed. A UE obtains configuration information of a data transmission from a neighboring cell via an interference channel in a mobile communication network. The UE receives radio signals on a set of data resource elements as determined based on the obtained configuration information. The UE then estimates the interference channel corresponding to the data transmission from the neighboring cell based on the received radio signals on the set of data resource elements. Finally, the UE cancels the data transmission from the neighboring cell based on the estimated interference channel.

Abstract: A method of interference cancellation is proposed. A UE obtains configuration information of a data transmission from a neighboring cell via an interference channel in a mobile communication network. The UE receives radio signals on a set of data resource elements as determined based on the obtained configuration information. The UE then estimates the interference channel corresponding to the data transmission from the neighboring cell based on the received radio signals on the set of data resource elements. Finally, the UE cancels the data transmission from the neighboring cell based on the estimated interference channel.

Abstract: A method of interference cancellation is proposed. A UE obtains configuration information of a data transmission from a neighboring cell via an interference channel in a mobile communication network. The UE receives radio signals on a set of data resource elements as determined based on the obtained configuration information. The UE then estimates the interference channel corresponding to the data transmission from the neighboring cell based on the received radio signals on the set of data resource elements. Finally, the UE cancels the data transmission from the neighboring cell based on the estimated interference channel.

Abstract: A new air interface that is interference cancellation friendly is proposed. In one novel aspect, a novel code rate assignment with rate splitting is proposed. In one embodiment, a base station decomposes a codeword {x1} into two codewords {x1a} and {x1b}. The two codewords are applied with different code rates and/or modulation orders. More specifically, the code rate or modulation order of codeword {x1a} is set appropriately so that a victim UE can decode and cancel {1a} under the channel quality of the victim UE. Typically, the channel quality of a victim UE is poorer than the channel quality of the intended UE. As a result, the MCS for {1a} can be lower than the MCS for {1b} such that the victim UE is able to apply CWIC to decode and cancel {1a}.

Abstract: A new air interface that is interference cancellation friendly is proposed. In one novel aspect, addition information is provided between eNB and UE for interference cancellation. From eNB perspective, it provides assistance information to UEs for CWIC. The assistance information may include modulation order and code rate information of the PDSCH for data transmission that may cause interference to other UEs. From UE perspective, it provides feedback information to the eNB for MCS level assignment. The feedback information may include additional channel quality and interference condition information of a data transmission of a desired transport block with respect to the decoding of the desired transport block.

Abstract: Methods of enabling multiuser superposition transmission (MUST) in LTE systems are proposed. MUST operation allows simultaneous transmission for multiple co-channel users on the same time-frequency resources. A higher-layer signaling is used for configuring a UE to enable MUST. When a UE is configured by higher layer to enable MUST, the UE will monitor physical-layer control signaling carrying scheduling information and MUST-related information. Depending on whether MUST exists in each subframe, the UE derives the power allocation between the UE and its co-channel UE on allocated resource blocks. The UE also derives the power allocation based on whether it is configured for CRS-based transmission mode or DMRS-based transmission mode.

Abstract: A method of interference cancellation is proposed. A UE obtains configuration information of a data transmission from a neighboring cell via an interference channel in a mobile communication network. The UE receives radio signals on a set of data resource elements as determined based on the obtained configuration information. The UE then estimates the interference channel corresponding to the data transmission from the neighboring cell based on the received radio signals on the set of data resource elements. Finally, the UE cancels the data transmission from the neighboring cell based on the estimated interference channel.

Abstract: A method of modulating and demodulating superposed signals for MUST scheme is proposed. A transmitter takes bit sequences intended for multiple receivers under MUST scheme to go through a “bit sequence to constellation points” mapper before entering the modulators to satisfy the Gray coding rule and to achieve high demodulation performance for the receivers. In a first method, each bit sequence is assigned for each constellation point on the constellation map to satisfy one or more conditions under different power split factors. In a second method, the constellation map is divided into sub-regions according to the clustering of the constellation points for bit sequence assignment. A near-UE may use an ML receiver for demodulation and decoding the superposed signal. A far-UE may use an ML receiver or an MMSE receiver for demodulation and decoding the superposed signal.

Abstract: A method of modulating and demodulating superposed signals for MUST scheme is proposed. A transmitter takes bit sequences intended for multiple receivers under MUST scheme to go through a “bit sequence to constellation points” mapper before entering the modulators to satisfy the Gray coding rule and to achieve high demodulation performance for the receivers. In a first method, each bit sequence is assigned for each constellation point on the constellation map to satisfy one or more conditions under different power split factors. In a second method, the constellation map is divided into sub-regions according to the clustering of the constellation points for bit sequence assignment. A near-UE may use an ML receiver for demodulation and decoding the superposed signal. A far-UE may use an ML receiver or an MMSE receiver for demodulation and decoding the superposed signal.

Abstract: Methods of enabling multiuser superposition transmission (MUST) in LTE systems are proposed. MUST operation allows simultaneous transmission for multiple co-channel users on the same time-frequency resources. A higher-layer signaling is used for configuring a UE to enable MUST in each transmission mode (TM). MUST is a sub-TM of each TM. When a UE is configured by higher layer to enable MUST, the UE will monitor new DCI formats supported by the configured TM with new fields carrying scheduling information of another co-channel UE. Dynamic switching between MUST and non-MUST operation is allowed. Mixed transmission schemes and precoders among co-channel UEs are also supported.

Abstract: A method of performing downlink multiuser superposition transmission (MUST) when different precoders are applied to superposed signals is proposed. For demodulation reference signal (DM-RS) transmission mode, the near-user can estimate the far-user's channel by means of separate DM-RS symbols. For common reference signal (CRS) transmission mode, the near-user can blindly detect code far-user's precoder that is not signaled to the near-user. As a result, even the downlink control information (DCI) format is designed for the situation using the same precoder for superposed signals, the MUST scheme works and the near-user receiver can separate the superposed signal for the far-user.

Abstract: A method of performing downlink multiuser superposition transmission (MUST) with enhanced channel state information (CSI) feedback is proposed. When a user equipment (UE) reports CQI/SINR feedback for RI=RANK-2, the UE also reports a single beam CQI/SINR feedback for RI=RANK1. As a result, the scheduling base station can calculate the actual SINRs based on different MUST scenarios and thereby determining appropriate modulation and coding scheme (MCS) for the UE. Furthermore, if the granularity of the CQI table cannot reflect the high values of the single beam SINR, then a predefined scaling factor (0<?<1) known to both the base station and the UE may be applied.

Abstract: When the codeword level interference cancellation (CW-IC) is used at the receiver in conjunction with the superposition coding scheme at the transmitter, in order to guarantee the success of signal reception, restrictions of scheduling decisions in resource allocation of superposed transport blocks may occur. A method to mitigate the scheduling restrictions is proposed. For a low-geometry UE in NOMA operation, one sub-band is used as the basic scheduling unit. As a result, data in resource blocks scheduled for NOMA operation and data in resource blocks scheduled for other non-NOMA operation correspond to different transport blocks. Therefore, a high-geometric UE only needs to decode the data scheduled for NOMA. The base station does not need to impose additional scheduling restrictions and signaling overhead.