COMMUNICATION APPARATUS AND COMMUNICATION METHOD

Abstract

A communication apparatus transmits data by adaptively selecting at least one of an error-correction coding rate and a modulation method so that the error rate of data transmission is within a target error rate at a destination. In the communication apparatus, a transmission-parameter generating unit selects at least one of an error-correction coding rate and a modulation method based on the number of hops, transmission channel characteristics, and the target error rate, thus generating at least one transmission parameter, and an error-correction coding unit and a modulating unit adaptively perform either or both error-correction coding and modulation according to the transmission parameter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a detailed functional block diagram of a communication apparatus according to a first embodiment of the present invention;

FIG. 2 is a schematic of a communication network to which can be applied the communication apparatus shown in FIG. 1;

FIG. 3 is a schematic of a relay communication network including the communication apparatus;

FIG. 4 is a graph for explaining the relation between error rate and estimated transmission-channel characteristics for each modulation method;

FIG. 5 is a detailed functional block diagram of a communication apparatus according to a second embodiment of the present invention;

FIG. 6 is a detailed functional block diagram of a communication apparatus according to a third embodiment of the present invention;

FIG. 7 is an example of the structure of data added with control information; and

FIG. 8 is an example of a selection chart used to select a transmission parameter in conventional wireless communication.

Claims

1. A communication apparatus that constitutes a communication network in which data is transferred through a relay path including at least one relay link from a data-transfer origin to a destination so that an error rate of data transfer is within a target error rate at the destination, the communication apparatus comprising: a transmission-parameter generating unit that adaptively selects at least one of an error-correction coding rate and a modulation method for data to be transferred based on number of relay links in a relay path, characteristics of a transmission channel between the communication apparatus and a next-hop communication apparatus, and the target error rate to generate at least one transmission parameter; andan adaptive-modulation coding unit that performs at least one of error-correction coding and modulation of the data depending on contents of the transmission parameter.

2. The communication apparatus according to claim 1, wherein the target error rate is the same on all relay paths in the communication network, andthe transmission-parameter generating unit calculates an individual error rate on a corresponding relay link in a relay path used to transfer data to satisfy the target error rate, and selects at least one of the error-correction coding rate and the modulation method based on the number of relay links, the characteristics of the transmission channel, and the individual error rate.

3. The communication apparatus according to claim 1, further comprising: a data-transfer initiating unit that initiates the data transfer; andan individual-error-rate calculating unit that obtains the characteristics of each relay link in a relay path used to transfer data, and calculates an individual error rate on the relay link based on obtained characteristics and the target error rate, whereinthe transmission-parameter generating unit selects at least one of the error-correction coding rate and the modulation method based on the number of relay links, the characteristics of the transmission channel, and the individual error rate.

4. The communication apparatus according to claim 3, further comprising: a data relaying unit that relays data from a previous-hop communication apparatus to a next-hop communication apparatus; andan individual-error-rate obtaining unit that obtains the individual error rate from a communication apparatus that initiates the data transfer, whereinthe transmission-parameter generating unit selects at least one of the error-correction coding rate and the modulation method based on the number of relay links, the characteristics of the transmission channel, and the individual error rate.

5. The communication apparatus according to claim 1, wherein the target error rate is non-variable.

6. The communication apparatus according to claim 1, wherein the target error rate varies according to at least one of type and amount of data to be transferred.

7. The communication apparatus according to claim 1, further comprising: a data-transfer initiating unit that initiates the data transfer;a target-error-rate determining unit that determines a target error rate at a destination according to at least one of type and amount of data to be transferred; anda control-information generating unit that generates control information including a determined target error rate and number of relay links in a relay path to the destination, whereinthe transmission-parameter generating unit selects at least one of the error-correction coding rate and the modulation method based on the control information and the characteristics of the transmission channel, andthe adaptive-modulation coding unit performs at least one of the error-correction coding and the modulation of the data added with the control information.

8. The communication apparatus according to claim 7, further comprising: a data relaying unit that relays data from a previous-hop communication apparatus to a next-hop communication apparatus; anda control-information extracting unit that extracts the control information from the data, whereinthe transmission-parameter generating unit selects at least one of the error-correction coding rate and the modulation method base on extracted control information and the characteristics of the transmission channel.

9. A communication method of transferring data through a relay path including at least one relay link from a communication apparatus at a data-transfer origin to a communication apparatus at a destination in a communication network so that an error rate of data transfer is within a target error rate at the destination, the communication method comprising: adaptively selecting at least one of an error-correction coding rate and a modulation method for data to be transferred based on number of relay links in a relay path, characteristics of a transmission channel between the communication apparatus at the data-transfer origin and a next-hop communication apparatus, and the target error rate to generate at least one transmission parameter; andperforming at least one of error-correction coding and modulation of the data depending on contents of the transmission parameter.