Grouping based reference signal transmission for massive MIMO scheme

A method for a base station to operate in a wireless communication system employing a massive Multiple Input Multiple Output (MIMO) scheme, the method comprising:

• transmitting information on a sequence used for an uplink reference signal to user equipments (UEs), wherein the information is determined to assign orthogonal sequences to the UEs within a UE group considering at least one or more of a number of orthogonal sequences, a number of the UEs within the UE group, an amount of information to be transmitted, a channel condition between the base station and each UE, and a number of sequences assigned to each UE of the UEs;
• and
• receiving the uplink reference signals from the UEs using the sequence identified by the information,
• wherein the number of sequences assigned to each UE is determined based on a number of singular values greater than a threshold value, and
• wherein the singular values are of a covariance matrix of a channel between the base station and each UE.

A user equipment (UE) operating in a wireless communication system employing a massive Multiple Input Multiple Output (MIMO) scheme, the UE comprising:

• a receiver configured to receive information on a sequence used for an uplink reference signal from a base station, wherein the information is determined to assign orthogonal sequences to UEs within a UE group considering at least one or more of a number of orthogonal sequences, a number of the UEs within the UE group, an amount of information to be transmitted, a channel condition between the base station and each UE, and a number of sequences assigned to each UE of the UEs;
• a transmitter configured to transmit the uplink reference signal to the base station using the sequence identified by the information;
• and
• a processor connected to the receiver and transmitter,
• wherein the number of sequences assigned to each UE is determined based on a number of singular values greater than a threshold value, and
• wherein the singular values are of a covariance matrix of a channel between the base station and each UE.

A base station operating in a wireless communication system employing a massive Multiple Input Multiple Output (MIMO) scheme, the base station comprising:

• a transmitter configured to transmit transmitting information on a sequence used for an uplink reference signal to user equipments (UEs), wherein the information is determined to assign orthogonal sequences to the UEs within a UE group considering at least one or more of a number of orthogonal sequences, a number of the UEs within the UE group, an amount of information to be transmitted, a channel condition between the base station and each UE, and a number of sequences assigned to each UE of the UEs;
• a receiver configured to receive the uplink reference signals from the UEs using the sequence identified by the information;
• and
• a processor connected to the transmitter and the receiver,
• wherein the number of sequences assigned to each UE is determined based on a number of singular values greater than a threshold value, and
• wherein the singular values are of a covariance matrix of a channel between the base station and each UE.