USER TERMINAL, RADIO BASE STATION AND ADAPTIVE MODULATION AND CODING METHOD

• US 20150365181A1
• Filed: 01/20/2014
• Published: 12/17/2015
• Est. Priority Date: 01/29/2013
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Nagata, Satoshi, Mu, Qin, Liu, Liu, Jiang, Yu, Chen, Lan
• Granted Patent: US 9,667,361 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04L 1/00 Arrangements for detecting or preventing errors in the information received correcting synchronisation H04L7/00
• 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 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 27/2275 wherein the carrier recovery circuit uses the received modulated signals
• CPC Class Codes: H04L 27/2692 with preamble design, i.e. with negotiation of the synchronisation sequence with transmitter or sequence linked to the algorithm used at the receiver
• CPC Class Codes: H04L 27/34 Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
• CPC Class Codes: H04W 72/21 in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 72/51 based on terminal or device properties
• CPC Class Codes: H04W 74/002 Transmission of channel access control information
• CPC Class Codes: H04W 74/008 with additional processing of random access related information at receiving side

Abstract

The present invention is designed to make possible adaptive modulation and coding (AMC) that supports high-order modulation schemes. The adaptive modulation and coding method of the present invention is an adaptive modulation and coding method for a downlink shared channel, and includes, in a user terminal, the steps of measuring channel quality based on a reference signal from the radio base station, acquiring a channel quality indicator to indicate the modulation scheme and the coding rate that are applicable to the downlink shared channel in the channel quality, from a table in which channel quality indicators, modulation schemes and coding rates are associated with each other, and transmitting the channel quality indicator to the radio base station, and the modulation schemes include a modulation scheme of a higher order than 64 QAM.

Claims

1. A user terminal that receives a downlink shared channel from a radio base station, comprising:

a measurement section that measures channel quality based on a reference signal from the radio base station;

an acquisition section that acquires a channel quality indicator to indicate a modulation scheme and a coding rate that are applicable to the downlink shared channel in the channel quality, from a table, in which channel quality indicators, modulation schemes and coding rates are associated with each other; and

a transmitting section that transmits the channel quality indicator to the radio base station,

wherein the modulation schemes include a modulation scheme of a higher order than 64 QAM (Quadrature Amplitude Modulation).

2. The user terminal according to claim 1, wherein the transmitting section expands a size of a channel quality indicator field in an uplink control channel or an uplink shared channel, and transmits the channel quality indicator by using the expanded channel quality indicator field.

3. The user terminal according to claim 1, wherein the transmitting section carries out joint encoding of a first bit part and a second bit part constituting the channel quality indicator, and transmits the channel quality indicator by using a channel quality indicator field in an uplink control channel.

4. The user terminal according to claim 1, wherein the transmitting section transmits the channel quality indicator by using a channel quality indicator field and a reference signal field in an uplink control channel.

5. The user terminal according to claim 1, wherein:

the table comprises a first sub-table, which includes channel quality indicators from a minimum value to a final value that is smaller than a maximum value, and a second sub-table, which includes channel quality indicators from a starting value that is bigger than the minimum value, to the maximum value; and

the transmitting section transmits an operation result, which is acquired based on the channel quality indicator and the starting value that is reported between radio base station and the user terminal, to the radio base station.

6. The user terminal according to claim 1, wherein:

the table comprises a first sub-table, which includes channel quality indicators from a minimum value to a final value that is smaller than a maximum value, and a second sub-table, which includes channel quality indicators from a starting value that is bigger than the minimum value, to the maximum value;

the transmitting section transmits an operation result, which is acquired based on the channel quality indicator, to the radio base station; and

the channel quality indicator is retrieved in accordance with a result of judgment as to whether or not the second sub-table is used, based on history of channel quality indicators.

7. The user terminal according to claim 1, wherein a combination of a modulations scheme and a coding rate in the table is punctured linearly or non-linearly so that a size of a channel quality indicator field in an uplink control channel or an uplink shared channel does not increase.

8. The user terminal according to claim 1, wherein the modulation scheme of a higher order than 64 QAM is 256 QAM (Quadrature Amplitude Modulation).

11. The user terminal according to claim 2, wherein the modulation scheme of a higher order than 64 QAM is 256 QAM (Quadrature Amplitude Modulation).

12. The user terminal according to claim 3, wherein the modulation scheme of a higher order than 64 QAM is 256 QAM (Quadrature Amplitude Modulation).

13. The user terminal according to claim 4, wherein the modulation scheme of a higher order than 64 QAM is 256 QAM (Quadrature Amplitude Modulation).

14. The user terminal according to claim 5, wherein the modulation scheme of a higher order than 64 QAM is 256 QAM (Quadrature Amplitude Modulation).

15. The user terminal according to claim 6, wherein the modulation scheme of a higher order than 64 QAM is 256 QAM (Quadrature Amplitude Modulation).

16. The user terminal according to claim 7, wherein the modulation scheme of a higher order than 64 QAM is 256 QAM (Quadrature Amplitude Modulation).

9. A radio base station that transmits a downlink shared channel to a user terminal, comprising:

a receiving section that receives a channel quality indicator from the user terminal;

an acquisition section that acquires a modulation scheme and a coding rate that correspond to the channel quality indicator received in the receiving section, from a table in which channel quality indicators, modulation schemes and coding rates are associated with each other; and

a transmitting section that transmits the downlink shared channel by applying the modulation scheme and the coding rate,

wherein the modulation schemes include a modulation scheme of a higher order than 64 QAM.

10. An adaptive modulation and coding method for a downlink shared channel, comprising, in a user terminal, the steps of:

measuring channel quality based on a reference signal from the radio base station;

acquiring a channel quality indicator to indicate a modulation scheme and a coding rate that are applicable to the downlink shared channel in the channel quality, from a table, in which channel quality indicators, modulation schemes and coding rates are associated with each other; and

transmitting the channel quality indicator to the radio base station, wherein the modulation schemes include a modulation scheme of a higher order than 64 QAM.