Adaptive modulation scheme and data rate control method

• US 20050197065A1
• Filed: 01/05/2005
• Published: 09/08/2005
• Est. Priority Date: 03/05/2004
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Saito, Toshiyuki, Yano, Takashi, Tamaki, Satoshi, Hanaoka, Seishi
• Granted Patent: US 7,801,236 B2
• Time in Patent Office: Days
• US Class Current: 455/42
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0021 in which the algorithm uses adaptive thresholds
• CPC Class Codes: H04L 27/0008 arrangements for allowing a transmitter or receiver to use more than one type of modulation negotiating modulation type for two-way transmission paths H04L5/1453
• CPC Class Codes: H04L 5/0046 Determination of how many bits are transmitted on different sub-channels
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling

Abstract

A transmitter station and receiver station have common maximum number of transmission bits per symbol of each subcarrier and information of encoding types to be selected. The transmitter station selects the modulation type from the propagation path quality of each subcarrier, executes the encoding with the encoding type corresponding to the number of bits for communication with the selected modulation type, distributes the maximum number of transmission bits per symbol of each subcarrier by dividing the code, and transmits the data through modulation of only the number of bits for communication with the selected modulation type among distributed bits in each subcarrier. The receiver station executes demodulation by selecting the modulation type used for demodulation from the propagation path quality, summarizes the demodulation result with addition of reception of the signal having a zero degree of likeliness for the number of wanted bits, and executes decoding to the result of demodulation.

Claims

1. A radio communication system comprising a first radio station for dividing codeword generated by encoding the transmission information into a plurality of communication units and transmitting the divided codewords by modulating these codewords in every communication unit and a second radio station for coupling and decoding the signals obtained by demodulating a plurality of communication units, wherein

the first and second radio stations have the common information of the first number of bits which is equal to the maximum bits per symbol of a plurality of communication units and an encoding type list including encoding types having different information bit lengths and equal code length after the encoding which can be used in the first radio station to encode the transmission information;

and

the first radio station generates codewords by encoding the transmission information with one of the encoding types listed in the encoding type list and divides the codeword into a plurality of communication units;

modulates and transmits a plurality of communication units each with a modulation type in which the number of bits per symbol is a second number of bits which is equal to or less than the first number of bits;

the second radio station receives a plurality of communication units modulated by the first radio station;

modulates respectively a plurality of communication units with a modulation type in which the number of bits per symbol is a third number of bits which is equal to or less than the first number of bits;

combines and decodes the demodulated signals of a plurality of communication units with one or a plurality of encoding types among those listed in the encoding type list; and

obtains the result of the decoding, as the reception information, by the encoding type in which no error is detected in the result of decoding.

2. The radio communication system according to claim 1, wherein the first radio station measures the propagation path condition up to the second radio station and selects an encoding type used for the encoding or a modulation type used for the modulation based on the measured propagation path condition.

3. The radio communication system according to claim 1, wherein the second radio station measures the propagation path condition up to the first radio station and selects, based on the measured propagation path condition, a modulation type used for the demodulation or an encoding type used for the decoding.

4. The radio communication system according to claim 1, having the common information of a first number of transmission bits and an encoding type list on the basis of the communication conducted between the first radio station and the second radio station prior to the transmission of the transmission information.

5. The radio communication system according to claim 1, wherein modulation is executed using the center frequency which is different for each of a plurality of communication units.

6. The radio communication system according to claim 1, wherein communication is executed through dispersion by different dispersion codes for each of a plurality of communication units.

7. The radio communication system according to claim 1, wherein the first radio station uses a plurality of antennas for transmission and conducts the communication using different antenna for each of a plurality of communication unit.

8. The radio communication system according to claim 1, wherein the first radio station uses a plurality of antennas for communication and executes the communication using different antenna for each result of primary conversion of the codeword divided into a plurality of communication units.

9. A transmitter station for transmitting the transmission information to a receiver station in the radio communication system, comprising:

a memory for storing the information of first number of transmission bits as the maximum bits per symbol for transmission of communication units divided from the codeword generated from the transmission information and an encoding type list including encoding types having different information bit lengths and equal code length after the encoding which can be used for encoding the transmission information;

a channel encoder for generating codeword by encoding the transmission information with one of the encoding types listed in the encoding type list;

a modulator for modulating a plurality of communication units divided from the codeword with a modulation type in which the number of bits per symbol is a second number of bits which is equal to or less than the first number of bits; and

a transmitter for transmitting the modulated communication units, wherein

the transmitter station has in common, with the receiver station, the information of the first number of transmission bits and the encoding type list.

10. The transmitter station according to claim 9, further comprising an adaptive controller for measuring the propagation path condition up to the receiver station and selecting an encoding type used for the encoding or a modulation type used for the modulation on the basis of the measured propagation path condition.

11. The transmitter station according to claim 9, having, in combination with the receiver station, the common information of the first number of transmission bits and the encoding type list on the basis of the communication executed to the receiver station prior to the transmission of the transmission information.

12. The transmitter station according to claim 9, wherein transmission is executed using different subcarrier for each of a plurality of communication units.

13. A receiver station for decoding the receiving information from the transmitter station in the radio communication system comprising:

a memory for storing the information of a first number of bits as the maximum number of transmission bits per symbol of communication unit for transmission from the transmitter station and an encoding type list including encoding types having different information bit lengths and equal code length after the encoding;

a receiver for receiving a plurality of communication units from the transmitter station;

a demodulator for executing the demodulation with a demodulation type in which the number of transmission bits per symbol for a plurality of communication units received is a third number of bits equal to or less than the first number of transmission bits; and

a channel decoder for the decoding with one or a plurality of encoding types among the encoding types listed in the encoding type list;

wherein the receiver station has in common, with the transmitter station, the information of the first number of transmission bits and the encoding type list; and

the channel decoder obtains the result, as the receiving information, of the decoding by the encoding type in which no error is detected in the decoding result.

14. The receiver station according to claim 13, wherein the channel decoder sequentially selects an encoding type listed in the encoding type list, performs the decoding with the selected encoding type, and also performs the decoding with different encoding type when an error is detected in the decoding result.

15. The receiver station according to claim 13, wherein the channel decoder selects an encoding type based on the receiving signal quality from the encoding type listed in the encoding type list, performs the decoding with the selected encoding type, obtains the decoding result as the receiving information when no error is detected in the decoding result, and performs the decoding with different encoding type when an error is detected in the decoding result.

16. The receiver station according to claim 13, wherein the channel decoder selects the encoding type, in which no error is detected in the decoding of the other signal, from the encoding type listed in the encoding type list, performs the decoding with the selected encoding type, obtains the decoding result as the receiving information when no error is detected in the decoding result, and performs the decoding with different encoding type when an error is detected in the decoding result.

17. The receiver station according to claim 13, further comprising an adaptive controller for measuring the propagation path condition up to the transmitter station and for selecting an encoding type used for the decoding or a modulation type used for the demodulation according to the measured propagation path condition.

18. The receiver station according to claim 13 having in common, in combination with the transmitter station, the information of the first number of transmission bits and the encoding type list based on the communication executed to the transmitter station prior to the transmission of the transmission information.

19. The receiver station according to claim 13, wherein a plurality of communication units are transmitted using different subcarriers.