Information processing apparatus, transmission-side apparatus and method

An information processing apparatus comprising a controller configured to, when signals are simultaneously received from K transmission-side apparatuses (K:

• a positive integer) by a receiving antenna, and repetition of repeatedly and successively transmitting the same signal N times (N:
• a positive integer) is performed by the K transmission-side apparatuses:
• acquire a received reference signal r(n) (n=1, . . . , N) that is received by the receiving antenna by the n-th reference signal transmission in the repetition, the received reference signal r(n) including a transmitted reference signal x(k,n) (k=1, . . . , K) from each of the K transmission-side apparatuses, the transmitted reference signal x(k,n) given a phase rotation amount φ(g,n) that is assigned to a group g (g=1, . . . , G) to which the transmission-side apparatus k belongs among G groups (G:
• a positive integer;
• 1<G≤K) made by dividing the K transmission-side apparatuses;
• acquires, by giving a phase rotation amount opposite to the phase rotation amount φ(g,n) for the group g to the received reference signal r(n) and adding the first to N-th received reference signals in the repetition, a received reference signal r(g) (g=1, . . . , G) of the group g that includes received reference signals from one or more transmission-side apparatuses belonging to the group g;
• and
• performs communication channel estimation based on the received reference signal r(g) (g=1, . . . , G).