Communication device, communication method and communication system

1. A communication device comprising:

a first communicating unit that performs wireless communication with an external device on a first carrier wave at a first frequency;

a second communicating unit that has a plurality of antennas, and that performs the wireless communication with the external device on a second carrier wave at a second frequency, wherein a directionality of the second carrier wave is stronger than a directionality of the first carrier, and wherein the second carrier wave causes a larger propagation loss than the first carrier wave causes;

a first communication processing unit that processes a signal received by the first communicating unit, and that allows the first communicating unit to transmit a signal; and

a second communication processing unit that processes a signal received by the second communicating unit, and that allows the second communicating unit to transmit a signal,

wherein the second communication processing unit includes

an adjusting unit that adjusts a signal to be transmitted from each of the plurality of antennas based on an adjustment factor for the each of the plurality of antennas, the adjustment factor derived by a loop back transfer function among the plurality of antennas,

a transmission beam pattern candidate setting unit that derives at least one transmission beam pattern for defining a beam directionality of the signal to be transmitted based on a first transmission request received by the first communicating unit and a second transmission request received by the second communicating unit, and that sets the derived at least one transmission beam pattern as at least one transmission beam pattern candidate to be applied to the signal to be transmitted, and

a beam pattern applying unit that applies any of the set at least one transmission beam pattern candidate based on first requested-beam-pattern identification information transferred from the first communication processing unit, the first requested-beam-pattern identification information specifying a beam pattern of which transmission is requested by the external device.

2. The communication device according to claim 1 ,

wherein the transmission beam pattern candidate setting unit includes

a synchronizing unit that locates a starting position of the second transmission request based on packet positional information transferred from the first communication processing unit, the packet positional information indicating a position of a predetermined packet included in the first transmission request,

a transfer function deriving unit that derives a transfer function based on the second transmission request whose starting position is located by the synchronizing unit, and

a transmission beam pattern candidate storing unit that derives the transmission beam pattern based on the transfer function derived by the transfer function deriving unit, and in which the derived transmission beam pattern is stored as the transmission beam pattern candidate.

3. The communication device according to claim 2 ,

wherein the second communicating unit receives the second transmission request, one packet of which nominates a plurality of transmission beam patterns, and

wherein the second communication processing unit further includes

a reception strength deriving unit that derives a reception strength for each of the nominated plurality of transmission beam patterns based on the second transmission request whose starting position is located by the synchronizing unit,

a requested-beam-pattern determining unit that determines, out of the plurality of transmission beam patterns nominated in the packet of the second transmission request, a beam pattern to request the external device to transmit data in, based on a derivation result from the reception strength deriving unit, the second transmission request having been transmitted from the external device, and

a processing unit that allows, via the first communication processing unit, second requested-beam-pattern identification information to be transmitted to the external device, which transmits the second transmission request, the second requested-beam-pattern identification information indicating the beam pattern determined by the requested-beam-pattern determining unit.

4. The communication device according to claim 3 ,

wherein the second requested-beam-pattern identification information is a number indicating the beam pattern determined by the requested-beam-pattern determining unit.

5. The communication device according to claim 2 ,

wherein the second communication processing unit further includes a processing unit that allows the second communicating unit to transmit a third transmission request, one packet of which nominates one or more transmission beam pattern candidates stored in the transmission beam pattern candidate storing unit.

6. The communication device according to claim 1 ,

wherein the adjusting unit includes

an adjustment reference signal generating unit that generates an adjustment reference signal for a reference for deriving the loop back transfer function,

a transfer function deriving unit that derives the loop back transfer function for each of the plurality of antennas based on a reception result acquired by transmitting the adjustment reference signal from the each of the plurality of antennas and receiving the transmitted adjustment reference signal at another of the plurality of antennas,

an adjustment factor deriving unit that derives the adjustment factor based on the loop back transfer function derived by the transfer function deriving unit, and

a multiplying unit that multiplies the signal to be transmitted by the adjustment factor.

7. A communication method comprising the steps of:

transmitting, at a transmitting device, synchronously a first transmission request using a first carrier wave at a first frequency and a second transmission request using a second carrier wave at a second frequency, one packet of the second transmission request nominating a plurality of transmission beam patterns for defining a beam directionality of the signal to be transmitted, wherein a directionality of the second carrier wave is stronger than a directionality of the first carrier, and wherein the second carrier wave causes a larger propagation loss than the first carrier wave causes;

locating, by a receiving device, a starting position of the second transmission request, based on a position of a predetermined packet included in the first transmission request;

determining, at the receiving device, out of the plurality of transmission beam patterns nominated in the packet of the second transmission request, a beam pattern to request the transmitting device to transmit a data in;

transmitting, at the receiving device, requested-beam-pattern identification information indicating the determined beam pattern to request;

determining, at the transmitting device, a beam pattern for use in transmitting the data on the second carrier wave, based on the requested-beam-pattern identification information; and

transmitting, at the transmitting device, the data on the second carrier wave, to which the determined beam pattern for use in transmitting the data is applied.

8. A communication system comprising:

a plurality of communication devices, each of which is capable of transmitting a signal and receiving a signal transmitted from an external device,

wherein each of the communication devices includes

a first communicating unit that performs wireless communication with an external device on a first carrier wave at a first frequency,

a second communicating unit that has a plurality of antennas, and that performs the wireless communication with the external device on a second carrier wave at a second frequency, wherein a directionality of the second carrier wave is stronger than a directionality of the first carrier, and wherein the second carrier wave causes a larger propagation loss than the first carrier wave causes,

a first communication processing unit that processes a signal received by the first communicating unit, and that allows the first communicating unit to transmit a signal, and

a second communication processing unit that processes a signal received by the second communicating unit, and that allows the second communicating unit to transmit a signal, and

wherein the second communication processing unit includes

an adjusting unit that adjusts a signal to be transmitted from each of the plurality of antennas based on an adjustment factor for the each of the plurality of antennas, the adjustment factor derived by a loop back transfer function among the plurality of antennas,

a transmission beam pattern candidate setting unit that derives at least one transmission beam pattern for defining a beam directionality of the signal to be transmitted based on a first transmission request received by the first communicating unit and a second transmission request received by the second communicating unit, and that sets the derived at least one transmission beam pattern as at least one transmission beam pattern candidate to be applied to the signal to be transmitted, and

a beam pattern applying unit that applies any of the set at least one transmission beam pattern candidate based on first requested-beam-pattern identification information transferred from the first communication processing unit, the first requested-beam-pattern identification information specifying a beam pattern of which transmission is requested by the external device.