Adaptive modulation coding system and method in a mobile communication network

• US 20030231706A1
• Filed: 06/17/2003
• Published: 12/18/2003
• Est. Priority Date: 06/18/2002
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Hwang, In Tae
• Granted Patent: US 7,379,492 B2
• Time in Patent Office: Days
• US Class Current: 375/219
• 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 1/0015 characterised by the adaptation strategy
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/0656 Cyclotomic systems, e.g. Bell Labs Layered Space-Time [BLAST]

Abstract

An encoding method in a mobile communication system is provided. The method comprises selecting at least one adaptive coding rate and at least one modulation method according to estimated forward channel characteristics for a plurality of transmission antennas, based on BLAST-decoded signals received from a plurality of reception antennas; coding and modulating a plurality of transmission signal layers generated for transmission by the plurality of transmission antennas according to the selected adaptive coding rate and modulation method; and transmitting the plurality of transmission signal layers to the plurality of transmission antennas simultaneously by way of V-BLAST-coding.

Claims

1. A signal coding apparatus for a mobile communication system, the apparatus comprising:

an AMC receiver for BLAST-decoding signals received from a plurality of reception antennas, and estimating forward channel characteristics for a plurality of transmission antennas; and

an AMC transmitter for selecting at least one adaptive coding rate and at least one modulation method according to the estimated forward channel characteristics, coding and modulating a plurality of transmission signal layers generated for transmission by the plurality of transmission antennas according to the selected adaptive coding rate and modulation method, and transmitting the plurality of transmission signal layers to the plurality of transmission antennas simultaneously by way of BLAST-coding.

2. The apparatus of claim 1, wherein the plurality of transmission signal layers are generated based on the number of the plurality of transmission antennas.

3. The apparatus of claim 1, wherein the AMC receiver is operational to receive communication signals in a mobile terminal.

4. The apparatus of claim 1, wherein the AMC transmitter is operational to transmit communication signals in a base station.

5. The apparatus of claim 1, wherein the AMC receiver comprises:

a BLAST decoder for BLAST-decoding signals received from the plurality of reception antennas to produce at least one symbol; and

a channel estimator for estimating forward channel characteristics of the transmission antennas based on the symbol.

6. The apparatus of claim 5, further comprising:

a demodulator for

detecting a demodulation method based on the forward channel characteristics; and

demodulating the symbol based on the demodulation method.

7. The apparatus of claim 6, further comprising:

a channel deinterleaver for channel-deinterleaving of the symbol demodulated by the demodulator.

8. The apparatus of claim 7, further comprising:

a decoder for decoding output from the channel deinterleaver.

9. The apparatus of claim 5, wherein the AMC receiver further comprises:

a demodulator for detecting a demodulation method based on the forward channel characteristics; and

demodulating the symbol based on the demodulation method;

a channel deinterleaver for channel-deinterleaving of the symbol demodulated by the demodulator; and

a decoder for decoding output from the channel deinterleaver.

10. The apparatus of claim 1, wherein the AMC transmitter comprises:

a MCS level selector for selecting an optimum coding rate and modulation method according to the estimated forward channel characteristics; and

an encoder for encoding the plurality of transmission signal layers, according to the selected adaptive coding rate and the modulation method.

11. The apparatus of claim 10, wherein the AMC transmitter further comprises:

a channel interleaver for channel-interleaving the encoded plurality of transmission signal layers according to the coding rate.

12. The apparatus of claim 11, wherein the AMC transmitter further comprises:

a modulator for modulating the plurality of transmission signal layers produced the channel interleaver according to the modulation method.

13. The apparatus of claim 12, wherein the AMC transmitter further comprises:

a BLAST processing unit for transmitting at least one symbol in the plurality of transmission signal layers to the plurality of transmission antennas simultaneously by way of BLAST-coding, wherein the transmission symbol has a vertical form in temporal and spatial axes.

28. The method of claim 6, wherein the BLAST-decoding comprises:

arranging the signals received from the plurality of reception antennas as a reception vector;

estimating a certain symbol by regarding other symbols in the signals as an interference signal while estimating the certain symbol; and

subtracting a first-detected signal components from the reception vector.

29. The method of claim 6, wherein the V-BLAST coding comprises:

transmitting transmission data of each plurality of transmission signal layers to each of the plurality of transmission antennas simultaneously such that the transmission data of each of the plurality of transmission signal layers has a vertical form in temporal and spatial axes.

14. A mobile terminal in communication with a base station in a mobile communications network, the mobile terminal comprising an adaptive modulation (AMC) system wherein the AMC system comprises an AMC receiver for BLAST-decoding signals received from a plurality of reception antennas, and estimating forward channel characteristics for a plurality of transmission antennas.

15. The mobile terminal of claim 14, wherein the AMC receiver comprises:

a BLAST decoder for BLAST-decoding signals received from the plurality of reception antennas to produce at least one symbol;

a channel estimator for estimating forward channel characteristics of the transmission antennas based on the symbol;

a demodulator for detecting a demodulation method based on the forward channel characteristics; and

demodulating the symbol based on the demodulation method;

a channel deinterleaver for channel-deinterleaving of the symbol demodulated by the demodulator; and

a decoder for decoding output from the channel deinterleaver.

16. A base station in a mobile communications network in communication with a mobile terminal, the base station comprising an adaptive modulation (AMC) system wherein the AMC system comprises an AMC transmitter for:

selecting at least one adaptive coding rate and at least one modulation method according to forward channel characteristics provided by a mobile terminal,

coding and modulating a plurality of transmission signal layers generated for transmission by a plurality of transmission antennas according to the selected adaptive coding rate and modulation method, and

transmitting the plurality of transmission signal layers to the plurality of transmission antennas simultaneously by way of BLAST-coding.

17. The base station of claim 16, wherein the AMC transmitter comprises:

a MCS level selector for selecting an optimum coding rate and modulation method according to the estimated forward channel characteristics; and

an encoder for encoding transmission signal layers, according to the selected adaptive coding rate and the modulation method.

18. The base station of claim 17, wherein the AMC transmitter further comprises a channel interleaver for channel-interleaving the encoded transmission signal layers according to the coding rate.

19. The base station of claim 18, wherein the AMC transmitter further comprises a modulator for modulating the transmission signal layers produced the channel interleaver according to the modulation method.

20. The base station of claim 19, wherein the AMC transmitter further comprises a BLAST processing unit for transmitting at least one symbol in the transmission signal layers to the plurality of transmission antennas simultaneously by way of BLAST-coding, wherein the transmission symbol has a vertical form in temporal and spatial axes.

21. An adaptive modulation coding (AMC) method for a mobile communication system, the method comprising:

selecting at least one adaptive coding rate and at least one modulation method according to estimated forward channel characteristics for a plurality of transmission antennas in a base station of the mobile communication system, based on BLAST-decoded signals received from a plurality of reception antennas of a mobile terminal in communication with said base station;

coding and modulating a plurality of transmission signal layers generated for transmission by the plurality of transmission antennas according to the selected adaptive coding rate and modulation method; and

transmitting the plurality of transmission signal layers to the plurality of transmission antennas simultaneously by way of V-BLAST-coding.

22. The method of claim 21, wherein the selecting comprises:

selecting a 1/3 coding rate and a QPSK method when SNR of a forward channel is not greater than a first threshold value.

23. The method of claim 21, wherein the selecting comprises:

selecting a 2/3 coding rate and a QPSK method when SNR of a forward channel is not less than the first threshold value and not greater than a second threshold value.

24. The method of claim 21, wherein the selecting comprises:

selecting a 2/3 coding rate and a 8PSK method when SNR of a forward channel is not less than the second threshold value and not greater than a third threshold value.

25. The method of claim 21, wherein the selecting comprises:

selecting a 2/3 coding rate and a 16QAM method when SNR of a forward channel is not less than the third threshold value.

26. The method of claim 21, wherein the selecting comprises:

selecting a 1/3 coding rate and a QPSK method when SNR of a forward channel is not greater than a first threshold value;

selecting a 2/3 coding rate and a QPSK method when SNR of a forward channel is not less than the first threshold value and not greater than a second threshold value;

selecting a 2/3 coding rate and a 8PSK method when SNR of a forward channel is not less than the second threshold value and not greater than a third threshold value; and

selecting a 2/3 coding rate and a 16QAM method when SNR of a forward channel is not less than the third threshold value.

27. The method of claim 21, wherein the selecting comprises applying a coding rate and modulation method to at least one of the plurality of transmission antennas.

30. An encoding method in a mobile communication system comprising:

selecting at least one adaptive coding rate and at least one modulation method according to estimated forward channel characteristics for a plurality of transmission antennas, based on BLAST-decoded signals received from a plurality of reception antennas;

coding and modulating a plurality of transmission signal layers generated for transmission by the plurality of transmission antennas according to the selected adaptive coding rate and modulation method; and

transmitting the plurality of transmission signal layers to the plurality of transmission antennas simultaneously by way of V-BLAST-coding.