Hybrid ARQ technique for data transmission
First Claim
1. A hybrid ARQ method of operating a transmitter for transmitting a data unit on a radio channel in a communication system to a receiver, the method comprising the steps of:
- encoding (700) the data unit into a sequence of at least two code words using at least one encoding parameter;
transmitting (720) a first code word;
receiving (730) a positive (ACK) or negative (NAK) acknowledgement message from the receiver indicating that the receiver was or was not able to decode the data unit; and
if a negative acknowledgement message was received, transmitting (740, 720) the next code word of the sequence and continuing with the receiving step;
characterised in that the method further comprises the step of determining (770) a measurement value indicating the current channel conditions, by counting (750) negative acknowledgement messages and/or evaluating the at least one encoding parameter.
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Abstract
The invention provides a hybrid ARQ technique for transmitting a data unit on a radio channel in a communication system to a receiver. After encoding the data unit into a sequence of code words using an encoding parameter, a first code word is transmitted, and an ACK or NAK is received from the receiver. If a NAK is received, the next code word of the sequence is transmitted. According to the invention, a measurement value indicating the current channel conditions is determined by counting the NAK messages and/or evaluating the encoding parameters. Preferably the measurement values are the overall coding rate, the average number of retransmissions per data unit, and the average number of retransmissions per code word. In the preferred embodiment, the transmitter comprises a NAK counter. Besides the improved transmission measurement, the present invention provides using this measurement for adaptation purposes.
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Citations
21 Claims
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1. A hybrid ARQ method of operating a transmitter for transmitting a data unit on a radio channel in a communication system to a receiver, the method comprising the steps of:
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encoding (700) the data unit into a sequence of at least two code words using at least one encoding parameter;
transmitting (720) a first code word;
receiving (730) a positive (ACK) or negative (NAK) acknowledgement message from the receiver indicating that the receiver was or was not able to decode the data unit; and
if a negative acknowledgement message was received, transmitting (740, 720) the next code word of the sequence and continuing with the receiving step;
characterised in that the method further comprises the step of determining (770) a measurement value indicating the current channel conditions, by counting (750) negative acknowledgement messages and/or evaluating the at least one encoding parameter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16)
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15. A hybrid ARQ transmitter for transmitting a data unit on a radio channel in a communication system to a receiver, comprising:
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an encoder (310) for encoding the data unit into a sequence of at least two code words using at least one encoding parameter;
a transmission unit (330, 340, 350, 400, 360) for transmitting a first code word;
a receiving unit (360, 400, 410, 420, 430) for receiving a positive (ACK) or negative (NAK) acknowledgement message from the receiver indicating that the receiver was or was not able to decode the data unit; and
means (440, 320) for operating the transmission unit for transmitting the next code word of the sequence if a negative acknowledgement message was received;
characterised by a measurement unit (600, 610) for determining a measurement value indicating the current channel conditions, by counting negative acknowledgement messages and/or evaluating the at least encoding parameter. - View Dependent Claims (17, 18, 19, 20, 21)
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Specification