Information processing apparatus, transmission-side apparatus and method
When signals are simultaneously received from K transmission-side apparatuses by a receiving antenna, and repetition is performed by the K transmission-side apparatuses, an information processing apparatus is configured to: in order to obtain a transmitted reference signal x(k,n) transmitted from a transmission-side apparatus k (k=1, . . . , K) by the n-th reference signal transmission in the repetition, acquire a phase rotation amount φ(g,n) given to a transmitted reference signal x(k) and assigned to a group g to which the transmission-side apparatus k belongs and transmit the phase rotation amount φ(g,n) to the transmission-side apparatus k. The phase rotation amount φ(g,n) is acquired so that received reference signals from transmission-side apparatuses not belonging to the group g are cancelled when a phase rotation amount opposite to the phase rotation amount φ(g,n) is given to a received reference signal r(n), and the first to N-th received reference signals in the repetition are added.
1. 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).
2. The information processing apparatus according to claim 1 , wherein the phase rotation amount φ(g,n) is a value such that received reference signals from transmission-side apparatuses not belonging to the group g are cancelled when giving the phase rotation amount opposite to the phase rotation amount φ(g,n) to the received reference signal r(n) and adding the first to N-th received reference signals in the repetition.
3. The information processing apparatus according to claim 2 , wherein the phase rotation amount φ(g,n) is a value such that a phase sequence Φg1 and a phase sequence Φg2 are orthogonal to each other in all of combinations of two groups g1 and g2 (g1=1, . . . , G; g2=1, . . . , G; g1≠g2) among the G groups.
4. The information processing apparatus according to claim 1 , wherein
the controller
acquires a data signal d by adding data signals d(n) corresponding to the N times in the repetition, each of the data signals d(n) transmitted from the K transmission-side apparatuses by the n-th data signal transmission in the repetition, received by the receiving antenna, and including a data signal d(k,n) from the transmission-side apparatus k (k=1, . . . , K); and
separates a data signal d(k) received from the transmission-side apparatus k, from the data signal d using a result of the communication channel estimation.
5. The information processing apparatus according to claim 1 , wherein the controller simultaneously receives signals from the K transmission-side apparatuses by M receiving antennas (M: a positive integer), and, when each of the K transmission-side apparatuses performs the repetition, executes the communication channel estimation for each receiving antenna.
6. A method executed by a computer comprising:
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,
acquiring 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;
acquiring 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
performing communication channel estimation based on the received reference signal r(g) (g=1, . . . , G).
7. The method according to claim 6 , wherein the phase rotation amount φ(g,n) is a value such that received reference signals from transmission-side apparatuses not belonging to the group g are cancelled when giving the phase rotation amount opposite to the phase rotation amount φ(g,n) to the received reference signal r(n) and adding the first to N-th received reference signals in the repetition.
8. The method according to claim 7 , wherein the phase rotation amount φ(g,n) is a value such that a phase sequence Φg1 and a phase sequence Φg2 are orthogonal to each other in all of combinations of two groups g1 and g2 (g1=1, . . . , G; g2=1, . . . , G; g1+g2) among the G groups.
9. The method according to claim 6 , further comprising:
acquiring a data signal d by adding data signals d(n) corresponding to the N times in the repetition, each of the data signals d(n) transmitted from the K transmission-side apparatuses by the n-th data signal transmission in the repetition, received by the receiving antenna, and including a data signal d(k,n) from the transmission-side apparatus k (k=1, . . . , K), and
separating a data signal d(k) received from the transmission-side apparatus k, from the data signal d using a result of the communication channel estimation.
10. The method according to claim 6 , wherein the computer simultaneously receives signals from the K transmission-side apparatuses by M receiving antennas (M: a positive integer), and, when each of the K transmission-side apparatuses performs the repetition, executes the communication channel estimation for each receiving antenna.