Abstract: Provided is an image pickup apparatus including, in order from an object side: a first lens unit; a stop; a second lens unit having a positive refractive power; and an image pickup element. The second lens unit includes a second lens sub-unit including only at least one positive lens. A refractive index (N2a) at a d-line of every lens included in the second lens sub-unit, an Abbe constant (?2a) and a partial dispersion ratio (?2a) of the every lens, a temperature-related relative refractive index change (dn2a/dTrelative) at the d-line, a focal length (f) of the overall system, a focal length (f2a) of the second lens sub-unit, an overall length (TD) of an image pickup lens, and a distance (BF) from an image-side surface of a lens arranged closest to an image side in the image pickup lens to an image plane of the image pickup element satisfy predetermined relationships.

Abstract: A terminal apparatus includes: a reception unit configured to receive a signal from a base station; a channel estimation unit configured to estimate a state of a channel based on a received signal; a storage configured to store a codebook including channel state values; an index of search number acquisition unit configured to acquire index of search number of candidates to be selected from among the channel state values for a correlation calculation with the estimated state value; a candidate selecting unit configured to select candidates for which the correlation calculation should be performed from among the channel state values according to the index of search number; a correlation calculation unit configured to calculate a correlation between the estimated state value and each of selected candidates; a selection unit configured to select a candidate having a highest correlation value; and a reporting unit configured to report a selected candidate to the base station.

Abstract: A wireless communication apparatus performs simultaneous communication with a plurality of communication terminals by using the same frequency band. The apparatus including: a reception unit that receives feedback information from each of the communication terminals; an acquisition unit that acquires a correlation value between the latest feedback information and the feedback information previously stored in a storage unit for each of the communication terminals; a measurement unit that measures a delay time relating to the feedback information; a generation unit that generates a reliability parameter representing degree of error that is allowed in the feedback information based on the correlation value and the delay time; and a selection unit that selects two or more of the communication terminals from among the plurality of the communication terminals based on the reliability parameter.

Abstract: A radio communications apparatus executing transmit beam forming includes a receiver which receives an estimate value of a propagation path response, a computer which calculates a weighting matrix to be used for the transmit beam forming, in accordance with the estimate value, a correcting unit which corrects a component, of components of the weighting matrix, and a beam forming unit which executes beam forming using the weighting matrix corrected by the correcting unit and executes radio transmission.