Communication apparatus and communication method thereof
The present invention is provided to improve transmission efficiency by preventing interference between different networks during data transmission using a multicarrier communication method. A transmitter includes a phase vector setting unit and a multicarrier modulator. The phase vector setting unit rotates a phase of transmission data corresponding to each subcarrier signal in an OFDM multicarrier signal, by generating a randomized phase vector for each subcarrier signal. The multicarrier modulator modulates the multicarrier signal as transmission data by using an inverse Fourier transform or an inverse wavelet transform. The phase vector setting unit changes a phase vector according to the status of a transmission line or the status of another network.
1 . A communication apparatus that performs data transmission employing a multicarrier communication method, the communication apparatus comprising:
a phase vector modification unit that changes a phase vector corresponding to at least one of a plurality of subcarrier signals, so that different networks have different phase vectors, the plurality of subcarrier signals being included in a multicarrier signal; and
a phase rotator that rotates a phase of at least one of the plurality of subcarrier signals based on the phase vector changed by the phase vector modification unit.
2 . The communication apparatus according to claim 1 ,
wherein the phase vector modification unit changes the phase vector, so that the phase vector is randomized for each of the subcarriers.
3 . The communication apparatus according to claim 1 ,
wherein, when a plurality of one of logically and physically separated networks are present, the phase vector modification unit changes a phase vector to be used for the communication apparatus itself, so that a network to which the communication apparatus belongs and another network have different phase vectors.
4 . The communication apparatus according to claim 3 ,
wherein, when the communication apparatus builds a network or when the communication apparatus is connected to an existing network, the phase vector modification unit changes the phase vector according to a code of the network to be set.
5 . The communication apparatus according to claim 3 ,
wherein, when detecting the another network, which differs from the network to which the communication apparatus belongs, the phase vector modification unit changes the phase vector.
6 . The communication apparatus according to claim 5 , further comprising:
a phase vector setting unit that stops a phase vector changing process by the phase vector modification unit, when the phase vector modification unit has not detected the another network during a predetermined time.
7 . The communication apparatus according to claim 5 ,
wherein, when detecting the another network, the phase vector modification unit further changes the phase vector only when a signal level of a multicarrier signal used for the detected another network is higher than a predetermined threshold.
8 . The communication apparatus according to claim 6 , further comprising:
a phase vector setting unit that stops the phase vector changing process by the phase vector modification unit, the communication apparatus being a remote unit of a network including a base unit and the remote unit,
wherein the phase vector modification unit detects a phase vector and a code of the network indicated in a multicarrier signal transmitted from another communication apparatus, and wherein the phase vector setting unit stops the phase vector changing process by the phase vector modification unit, when the phase vector detected by the phase vector modification unit is identical to the phase vector of the network to which the communication apparatus belongs, and when the code of the network detected by the phase vector modification unit is identical to the code of the network to which the communication apparatus belongs.
9 . The communication apparatus according to claim 3 ,
wherein, when detecting a communication apparatus of the another network, which differs from the network to which the communication apparatus belongs, and when the communication apparatus is a base unit of the network including the base unit and remote units, the phase vector modification unit changes the phase vectors of the communication apparatus and all the remote units connected to the network to which the communication apparatus belongs.
10 . The communication apparatus according to claim 3 ,
wherein, when detecting the communication apparatus of the another network, which differs from the network to which the communication apparatus belongs, and when the communication apparatus is a remote unit of the network including the base unit and remote units, the phase vector modification unit notifies the base unit of the network to which the communication apparatus belongs of the presence of the another network.
11 . The communication apparatus according to claim 1 ,
wherein the phase vector modification unit includes a random value generator that generates a random value by which a phase vector is generated.
12 . The communication apparatus according to claim 1 ,
wherein the phase vector modification unit includes a cyclic shift designator that performs a cyclic shift on a phase vector.
13 . The communication apparatus according to claim 1 ,
wherein, when determining the change of the phase vector deteriorates communication performance, the phase vector modification unit generates a new phase vector.
14 . The communication apparatus according to claim 1 , further comprising:
a transmission connecting unit that is connectable to a plurality of transmission lines.
15 . The communication apparatus according to claim 1 ,
wherein the communication apparatus uses a power line as its transmission line for data transmission.
16 . A communication method by which data transmission is performed employing a multicarrier communication, the communication method comprising:
changing a phase vector corresponding to at least one of a plurality of subcarrier signals, so that different networks have different phase vectors, the plurality of subcarrier signals being included in a multicarrier signal; and
rotating a phase of at least one of the plurality of subcarrier signals based on the changed phase vector.
17 . The communication method according to claim 16 , further comprising:
changing the phase vector, so that the phase vector is randomized for each of the subcarriers.
18 . The communication method according to claim 16 , further comprising:
changing a phase vector to be used for the communication apparatus itself, so that a network to which the communication apparatus belongs and another network have different phase vectors, when a plurality of one of logically and physically separated networks are present.
19 . The communication method according to claim 18 , further comprising:
changing the phase vectors of the communication apparatus and all the remote units connected to the network to which the communication apparatus belongs, when detecting a communication apparatus of the another network, which differs from the network to which the communication apparatus belongs, and when the communication apparatus is a base unit of the network including the base unit and remote units.
20 . An integrated circuit that performs data transmission employing a multicarrier communication method, the integrated circuit comprising:
a phase vector modification unit that changes a phase vector corresponding to at least one of a plurality of subcarrier signals, so that different networks have different phase vectors, the plurality of subcarrier signals being included in a multicarrier signal; and
a phase rotator that rotates a phase of at least one of the plurality of subcarrier signals based on the phase vector changed by the phase vector modification unit.
21 . A communication apparatus that performs data transmission via a power line employing a multicarrier communication method, the communication apparatus comprising:
a vector generator configured to generate a phase vector, the phase vector being a set of coefficients indicating a rotation degree corresponding to each of a plurality of subcarriers;
a receiver configured to receive from another communication apparatus a multicarrier signal having the plurality of subcarriers, the multicarrier communication signal including network information regarding a network of the another communication apparatus;
a demodulator configured to demodulate the multicarrier communication signal based on each of the plurality of subcarriers to generate a plurality of signal points, each of the plurality of signal points corresponding to each of the plurality of subcarriers; and
a phase rotator configured to rotate each of the plurality of signal points on a complex coordinate plane, based on each of the coefficients the set of which is the phase vector generated by the generator,
wherein the generator being further configured to change the phase vector generated by the generator into other phase vector, when each of the plurality of signal points rotated by the phase rotator indicates the network information included in the multicarrier communication signal.