Adaptive modulation and coding
First Claim
1. An adaptive modulation and coding method comprising:
- selecting one of a plurality of different available modulation and coding levels to apply to a signal transmitted from a transmitter to a receiver, the selection being based on a comparison between a signal transmission quality and a threshold value; and
adjusting the threshold value when the signal transmission quality is within a predetermined range of the threshold value, and maintaining the threshold value unchanged when the signal transmission quality is outside that range.
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Abstract
An adaptive modulation and coding method comprises selecting (S7) one of a plurality of different available modulation and coding levels to apply to a signal transmitted from a transmitter to a receiver. The selection is based on a comparison between a signal transmission quality (Îor/Ioc) and one or more threshold values. The or each threshold value is adjusted (S5, S6) when the signal transmission quality is within a predetermined range of that threshold value, and is maintained unchanged (S3) when the signal transmission quality is outside that range.
By maintaining the threshold value unchanged when the signal transmission quality is outside the range of that value the adjustments to the threshold value(s) are limited, whilst still enabling the threshold value(s) to take account of prevailing signal transmission conditions. This leads to improved throughput performance, especially under path conditions involving a single dominant path.
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Citations
23 Claims
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1. An adaptive modulation and coding method comprising:
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selecting one of a plurality of different available modulation and coding levels to apply to a signal transmitted from a transmitter to a receiver, the selection being based on a comparison between a signal transmission quality and a threshold value; and
adjusting the threshold value when the signal transmission quality is within a predetermined range of the threshold value, and maintaining the threshold value unchanged when the signal transmission quality is outside that range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. Adaptive modulation and coding apparatus comprising:
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a level selecting unit which selects one of a plurality of different available modulation and coding levels to apply to a signal transmitted from a transmitter to a receiver, the selection being based upon a comparison between a signal transmission quality and a threshold value; and
a threshold value adjusting unit operable, when the signal transmission quality is within a predetermined range of the threshold value, to adjust the threshold value, and also operable when the signal transmission quality is outside that range, to maintain the threshold value unchanged.
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20. A user equipment, for use in a wireless communication system, comprising:
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a level selecting unit which selects one of a plurality of different available modulation and coding levels to be applied by a base station of the system to a downlink signal transmitted from the base station to the user equipment, the selection being based on a comparison between a signal transmission quality and a threshold value;
a threshold value adjusting unit operable, when the signal transmission quality is within a predetermined range of the threshold value, to adjust the threshold value, and also operable, when the signal transmission quality is outside that range, to maintain the threshold value unchanged; and
reporting means for reporting the selected level to the base station.
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21. A base station, for use in a wireless communication system, comprising:
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a report receiving unit which receives from a user equipment of the system a report of a downlink signal transmission quality produced by the user equipment;
a level selecting unit which selects one of a plurality of different available modulation and coding levels to apply to a downlink signal transmitted from the base station to the user equipment, the selection being based upon a comparison between the reported downlink signal transmission quality and a threshold value; and
a threshold value adjusting unit operable, when the signal transmission quality is within a predetermined range of the threshold value, to adjust the threshold value, and also operable, when the signal transmission quality is outside that range, to maintain the threshold value unchanged.
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22. A recording medium storing an operating program which, when run on a processor in a user equipment of a wireless communication system, causes the user equipment to carry out the steps of:
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selecting one of a plurality of different available modulation and coding levels to be applied by a base station of the system to a downlink signal transmitted from the base station to the user equipment, the selection being based on a comparison between a signal transmission quality and a threshold value;
when the signal transmission quality is within a predetermined range of the threshold value, adjusting the threshold value, and, when the signal transmission quality is outside that range, and maintaining the threshold value unchanged; and
reporting the selected level to the base station.
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23. A recording medium carrying an operating program which, when run on a processor in a base station of a wireless communication system, causes the base station to carry out the steps of:
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receiving from a user equipment of the system a report of a downlink signal transmission quality produced by the user equipment;
selecting one of a plurality of different available modulation and coding levels to be applied by the base station to a downlink signal transmitted from the base station to the user equipment, the selection being based on a comparison between the reported downlink signal transmission quality and a threshold value; and
when the signal transmission quality is within a predetermined range of the threshold value, adjusting the threshold value, and when the signal transmission quality is outside that range, maintaining the threshold value unchanged.
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Specification