Apparatus and method for adaptive map channel decoding in radio telecommunication system
AssigneeSamsung Electronics Co., Ltd.
InventorsBeong-Jo Kim, Min-Goo Kim
Life of this patent
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Abstract
An adaptive MAP channel decoding apparatus and method in a mobile communication system. In the adaptive MAP channel decoding apparatus, a channel estimator calculates channel noise power and a scaling factor, a controller determines an operation mode by checking accumulated channel noise power and the scaling factor, and a MAP channel decoder performs a MAP decoding operation with an E function including a log function in a static channel mode and an E function free of a log function in a time-varying channel mode.
Claims12
An adaptive MAP channel decoding apparatus in a communication system, comprising:
- a channel estimator for calculating a channel noise power and a scaling factor;
- a controller for determining an operation mode according to the channel noise power and the scaling factor;
- and
- a MAP channel decoder having an E function operator for selectively operating in a static channel mode, according to the following equation:
- xEy=min(x, y)−log(1+e−|x−y|)
- and
- in a time-varying mode, according to the following equation:
- xEy=min(x, y)
- where x and y are metric values.
An adaptive MAP channel decoding method in a communication system, comprising the steps of:
- estimating a current channel state;
- performing an E function operation according to the following equation when the current channel state is static and performing a first MAP decoding operation:
- xEy=min(x, y)−log(1+e−|x−y|)
- where x and y are metric values;
- and
- performing the E function operation according to the following equation when the current channel state is time-varying and performing a second MAP decoding operation:
- xEy=min(x, y)
- where x and y are metric values.
A MAP channel decoding method adaptive to a current communication channel state in a mobile communication system, comprising the steps of:
- performing an E function operation without a log function according to the following equation:
- xEy=min(x, y)
- where x and y are the input of the E function operator;
- and
- performing a MAP channel decoding according to the following equations:
- [AutoLeftMatch] D k i ( m ) = ( L a ( d k ) + x k ) · i + y k · Y 1 i ( m ) A k i ( m ) = D k i ( m ) + min j = 0 1 ( A k - 1 i ( S b j ( m ) ) B k i ( m ) = min j = 0 1 ( B k + 1 i ( S b i ( m ) ) + D k + 1 j ( S f j ( m ) ) L ( d k ) = min m = 0 NS - 1 A k 0 ( m ) + B k 0 ( m ) - min m = 0 NS - 1 A k 1 ( m ) + B k 1 ( m ) }
- where Dki(m)=a BM
- La(dk)=extrinsic information obtained from a feed-back loop in the MAP channel decoder;
- xk=a systematic code;
- yk=a parity code;
- i=an expected systematic code;
- Yli(m)=an expected parity code;
- Aik(m)=a forward state metric (FSM)
- Sbi(m)=a backward changed state when an information bit is j to set a current state to m;
- Bki(m)=an RSM;
- Sfj(m)=a state changed forward when an information bit is input in a current encode state m;
- and
- L(dk)=an LLR when an information bit is dk at time k of MAP.
A receiving device in a communication system, comprising:
- a MAP channel decoder for decoding a signal received in a frame:
- a channel estimator for estimating the channel state of the input signal;
- and
- a controller for controlling the operation mode of the MAP channel decoder according to the estimated channel state value received from the channel estimator, wherein the channel decoder performs map decoding with a static mode or a time varying mode under the control of the controller.
An MAP channel decoding apparatus in a communication system, comprising:
- a receiver receiving a radio signal and outputting a corresponding demodulated signal;
- a MAP channel decoder for decoding the demodulated signal with an E function of following equation:
- xEy=min(x, y)
- where x and y are metric values.
Dependencies are inferred from the claim text.