Radio signal communication method, base station and terminal station

A base station in a communication system for controlling transmission of a data signal to each mobile terminal from said base station in accordance with a condition of a propagation path between said base station and said each mobile terminal, comprising:

• a transmission signal multiplexing unit for multiplexing a plurality of transmission signals transmitted to said mobile terminal;
• a transmission unit for transmitting said plurality of multiplexed transmission signals;
• a receiving unit for receiving a control signal transmitted from said mobile terminal;
• and
• a multiplexing scheme determining unit for determining a multiplexing scheme of said plurality of the transmission signals based on a control signal received from said mobile terminal;
• a space division multiplexing unit for multiplexing at least a plurality of transmission signals in a space domain, and a mobile terminal direction determining unit for determining a direction of the mobile terminal to which each of said transmission signals is transmitted;
• and
• an array antenna including a plurality of antennas for transmitting and receiving the signals to and from said mobile terminal,
• wherein each of said transmission signals includes a data signal and a dedicated pilot signal transmitted using a dedicated channel to said each mobile terminal,
• wherein said multiplexing scheme is selected from a plurality of signal multiplexing schemes, said plurality of signal multiplexing schemes include space division multiplexing, time division multiplexing, and code division multiplexing, and the space division multiplexing is higher in priority than the time division multiplexing or the code division multiplexing,
• wherein it is determined whether the transmission signals to said plurality of said mobile terminals are to be multiplexed by said space division multiplexing unit based on the directions of said plurality of said mobile terminals determined by said mobile terminal direction determining unit, and
• wherein said space division multiplexing unit determines an array weight of said array antenna for each of said plurality of said mobile terminals and carries out a beam-forming operation using said array weight.

A mobile terminal in a communication system for controlling a multiplexing scheme of the signal transmitted to each mobile terminal from a base station in accordance with a condition of a propagation path between said base station and said each mobile terminal, comprising:

• received signal separation unit for separating the signal transmitted to said mobile terminal from the signal multiplexed and transmitted by said base station;
• and
• a separation method determining unit for determining a separation method of separating the signal received from said base station;
• wherein said receiving signal separation unit separates the signal transmitted to said mobile terminal, based on the said separation method determined by said separation method determining unit,
• wherein said signal transmitted to said mobile terminal includes a data signal and a dedicated pilot signal to be transmitted to said mobile terminal, and
• wherein said multiplexing scheme is selected from a plurality of signal multiplexing schemes, the plurality of signal multiplexing schemes includes space division multiplexing, time division multiplexing, and code division multiplexing, and wherein the space division multiplexing is higher in priority than the time division multiplexing or the code division multiplexing,
• wherein said selected signal multiplexing scheme is selected based on selected one of a direction of each of said plurality of said mobile terminals with respect to said base station and a spatial correlation between said mobile terminals, and
• wherein the signal is transmitted from said base station to mobile terminal by determining a relation between the directions of said plurality of said mobile terminals, determining separability of the transmission signals to said plurality of said mobile terminals in a space domain based on said relation of their directions, and selecting the time division multiplexing and the space division multiplexing in the case where an angular difference between the mobile terminals in view from the base station exceeds a threshold value or a spatial correlation value between the mobile terminals is lower than a threshold value.