Patent ID: 11012111

Abstract:
In a case that a large number of terminal apparatuses that are accommodated by contention-based radio communication technologies share a frequency resource, the number of data signals of the terminal apparatus that are non-orthogonally multiplexed in the spatial domain increases. If terminal apparatuses, of which the number exceeds the number of receive antennas or the spreading factor transmit uplink data at the same time, it is tantamount to a presence of terminal apparatuses using the same spreading code, and inter-user interference becomes a problem. A transmitter for transmitting a data signal to a receiver, includes a transmission processing unit configured to transmit the data signal without receiving control information to permit transmission (UL grant) transmitted by the receiver; a spreading unit configured to spread the data signal; and a transmit power control unit capable of switching a plurality of methods of controlling transmit power of the data signal, wherein the methods of controlling transmit power are switched in accordance with at least one of a spreading factor or a sequence of spreading codes used by the spreading unit for spreading the data signal.