Journal of shanghai Jiaotong University (Science) ›› 2014, Vol. 19 ›› Issue (2): 173-180.doi: 10.1007/s12204-014-1487-5

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Pragmatic Physical Layer Abstraction Method Based on Bit-LLR-Wise Exponential Effective SNR Mapping for Bit Interleaved Coded Orthogonal Frequency Division Multiplexing System

Pragmatic Physical Layer Abstraction Method Based on Bit-LLR-Wise Exponential Effective SNR Mapping for Bit Interleaved Coded Orthogonal Frequency Division Multiplexing System

LI Meng-shi* (李孟实), YU Hui (俞 晖), LUO Han-wen (罗汉文), XU You-yun (徐友云)   

  1. (Institute of Wireless Communication Technology, Shanghai Jiaotong University, Shanghai 200240, China)
  2. (Institute of Wireless Communication Technology, Shanghai Jiaotong University, Shanghai 200240, China)
  • Online:2014-04-30 Published:2014-04-29
  • Contact: LI Meng-shi (李孟实) E-mail:jdaims.lim@sjtu.edu.cn

Abstract: In this paper, we analyze the physical layer abstraction for bit interleaved coded orthogonal frequency division multiplexing (BIC-OFDM) system from a parallel bit channel perspective. By combining the exponential effective SNR (signal-to-noise ratio) mapping (EESM) with the maximum a posteriori (MAP) algorithm, a bit LLR (log-likelihood ratio) wise EESM (BL-EESM) method is proposed. This method can abstract the link performance with high accuracy, especially for the case when channel estimation is imperfect. Afterward, the BL-EESM method is simplified by utilizing the non-linear quantization idea, which can reduce the times of exponential operation by two orders of magnitude at wide system bandwidth, yet shows little loss in accuracy. Our proposal can be applied to both system level simulations to save the time consumption and to practical terminals to facilitate the adaptive modulation and coding (AMC) procedure, bringing about throughput improvement at low hardware cost.

Key words: physical layer abstraction| parallel bit channel| signal-to-noise ratio (SNR)| exponential effective SNR mapping (EESM)| adaptive modulation and coding (AMC)| quantization

摘要: In this paper, we analyze the physical layer abstraction for bit interleaved coded orthogonal frequency division multiplexing (BIC-OFDM) system from a parallel bit channel perspective. By combining the exponential effective SNR (signal-to-noise ratio) mapping (EESM) with the maximum a posteriori (MAP) algorithm, a bit LLR (log-likelihood ratio) wise EESM (BL-EESM) method is proposed. This method can abstract the link performance with high accuracy, especially for the case when channel estimation is imperfect. Afterward, the BL-EESM method is simplified by utilizing the non-linear quantization idea, which can reduce the times of exponential operation by two orders of magnitude at wide system bandwidth, yet shows little loss in accuracy. Our proposal can be applied to both system level simulations to save the time consumption and to practical terminals to facilitate the adaptive modulation and coding (AMC) procedure, bringing about throughput improvement at low hardware cost.

关键词: physical layer abstraction| parallel bit channel| signal-to-noise ratio (SNR)| exponential effective SNR mapping (EESM)| adaptive modulation and coding (AMC)| quantization

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