Abstract: A Precoding-codebook-base Secure Uplink (PSU) scheme is proposed to utilize the channel reciprocity, uniqueness, and randomness in solving the secure initiation problem. A UE receives a first reference signal via first downlink channel in a mobile communication network. The UE performs channel estimation based on the first reference signal and thereby obtaining a first channel response matrix of the first downlink channel. The UE then encodes secrecy information onto a second reference signal. The UE transmits the second reference signal via a second uplink channel. The secrecy information is hidden in the uplink channel through a precoding operation such that the secrecy information can be extracted when the second uplink channel is reciprocal to the first downlink channel.

Abstract: A Precoding-codebook-base Secure Uplink (PSU) scheme is proposed to utilize the channel reciprocity, uniqueness, and randomness in solving the secure initiation problem. A UE receives a first reference signal via first downlink channel in a mobile communication network. The UE performs channel estimation based on the first reference signal and thereby obtaining a first channel response matrix of the first downlink channel. The UE then encodes secrecy information onto a second reference signal. The UE transmits the second reference signal via a second uplink channel. The secrecy information is hidden in the uplink channel through a precoding operation such that the secrecy information can be extracted when the second uplink channel is reciprocal to the first downlink channel.

Abstract: A method for reducing the quantization effect of precoding operations utilizing a finite codebook in MIMO systems is provided. First, at the receiver side, downlink channel state information is obtained and a set of indices of precoding matrices within a plurality of finite codebooks are selected accordingly. The selected indices of precoding matrices for each of the finite codebooks and a set of scalar coefficients are transmitted from the receiver to the transmitter. Thereafter, at the transmitter side, at least a first and a second refined precoding matrices are generated based on the selected set of indices of precoding matrices for all of the finite codebooks, and the one or more scalar coefficients and a final precoding matrix is generated at least based on the first refined precoding matrix and the second refined precoding matrix. The final precoding matrix is applied for transmission between the transmitter and the receiver.

Abstract: A method of handling a retransmission of a hybrid automatic repeat request scheme for a receiver in a communication system is disclosed. The method comprises receiving a first payload from a transmitter in the communication system, and feeding back a resource index to the transmitter, to indicate a size for a second payload in the next reception, when the receiver is unsuccessful to decode the first payload into a plurality of information bits, wherein the transmitter encodes the plurality of information bits into the first payload by using an error correction code.

Abstract: A method of reducing quantization error caused by precoding for a receiver in a wireless communication system is disclosed. The method comprising measuring channel information of a channel between the receiver and a transmitter in the wireless communication system; determining at least one precoding matrix from at least one codebook according to the channel information of the channel; determining at least one geometric coefficient according to a Geodesic interpolation algorithm and the at least one precoding matrix, for the at least one precoding matrix, respectively; and feeding back the at least one precoding matrix and the at least one geometric coefficient to the transmitter.

Abstract: A method of handling a retransmission of a hybrid automatic repeat request scheme for a receiver in a communication system is disclosed. The method comprises receiving a first payload from a transmitter in the communication system, and feeding back a resource index to the transmitter, to indicate a size for a second payload in the next reception, when the receiver is unsuccessful to decode the first payload into a plurality of information bits, wherein the transmitter encodes the plurality of information bits into the first payload by using an error correction code.

Abstract: A method for reducing the quantization effect of precoding operations utilizing a finite codebook in MIMO systems is provided. First, at the receiver side, downlink channel state information is obtained and a set of indices of precoding matrices within a plurality of finite codebooks are selected accordingly. The selected indices of precoding matrices for each of the finite codebooks and a set of scalar coefficients are transmitted from the receiver to the transmitter. Thereafter, at the transmitter side, at least a first and a second refined precoding matrices are generated based on the selected set of indices of precoding matrices for all of the finite codebooks, and the one or more scalar coefficients and a final precoding matrix is generated at least based on the first refined precoding matrix and the second refined precoding matrix. The final precoding matrix is applied for transmission between the transmitter and the receiver.

Abstract: A method for reducing the quantization effect of precoding operations utilizing a finite codebook in multiple-input multiple-output (MIMO) or multiple-input single-output (MISO) systems from a transmitter to a receiver is provided. First, downlink channel state information is obtained at the receiver side. A set of indices of precoding matrices or a set of precoding matrices within the finite codebook are determined according to the obtained downlink channel state information at the receiver side. The selected indices of precoding matrices and a set of scalar coefficients are transmitted from the receiver to the transmitter. Thereafter, a refined precoding matrix is generated based on the set of indices of precoding matrices and the one or more scalar coefficients at the transmitter side. The refined precoding matrix is applied for transmission between the transmitter and the receiver.