A low complexity 256QAM soft demapper for 5G mobile system

Mao, Juquan; Abdullahi, Mahmoud; Xiao, Pei; Cao, Aijun

doi:10.1109/eucnc.2016.7560996

Cited by 27 publications

(6 citation statements)

References 9 publications

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“…Note that this holds for a specific data frame for which the g k,t and p k,t can be regarded as constant values. The soft information at the ith bit is then expressed by the mean of log-likelihood ration (LLR) as [21] L i = ln…”

Section: B Maximum Likelihood Detectionmentioning

confidence: 99%

Output SNR analysis and detection criteria for optimum DCT-based multicarrier system

Zhang

Mao

et al. 2016

2016 International Symposium on Wireless Communication Systems (ISWCS)

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Abstract-The discrete cosine transform (DCT) based multicarrier system is regarded as one of the complementary multicarrier transmission techniques for 5th Generation (5G) applications in near future. By employing cosine basis as orthogonal functions for multiplexing each real-valued symbol with symbol period of T , it is able to reduce the minimum orthogonal frequency spacing to 1/(2T ) Hz, which is only half of that compared to discrete Fourier transform (DFT) based multicarrier systems. Critical to the optimal DCT-based system design that achieves interference-free single-tap equalization, not only both prefix and suffix are needed as symmetric extension of information block, but also a so-called front-end pre-filter is necessarily introduced at the receiver side. Since the pre-filtering process is essentially a time reversed convolution for continuous inputs, the output signal-to-noise ratio (SNR) for each subcarrier after filtering is enhanced. In this paper, the impact of pre-filtering on the system performance is analyzed in terms of ergodic output SNR per subcarrier. This is followed by reformulated detection criterion where such filtering process is taken into consideration. Numerical results show that under modified detection criteria, the proposed detection algorithms improve the overall bit error rate (BER) performance effectively.

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Section: B Maximum Likelihood Detectionmentioning

confidence: 99%

Output SNR analysis and detection criteria for optimum DCT-based multicarrier system

Zhang

Mao

et al. 2016

2016 International Symposium on Wireless Communication Systems (ISWCS)

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“…Because of noise colouration as a result of equalization, the performance of conventional demapper above can be enhanced in OFDM systems [16] by appropriately scaling the soft demapper using the variance of coloured noise. This was derived with the assumption that zero forcing equalization is optimum for OFDM systems as individaul subcarriers experience narrow-band fading.…”

Section: Zero Forcing Receivermentioning

confidence: 99%

Performance analysis and soft demapping for coded MIMO-OFDM systems

Abdullahi

Xiao

2016

2016 International Symposium on Wireless Communication Systems (ISWCS)

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Abstract-Multiple input multiple output-Orthogonal frequency division multiplexing (MIMO-OFDM) is a viable solution for providing high data rate services in harsh channel environments. The optimum receivers for them are those based on the maximum likelihood criterion. However, they have a prohibitive complexity especially when channel dimensions are high and coding is employed. Zero Forcing (ZF) and Linear Minimum Mean Square Error (MMSE) receivers on the other hand provide practicable and low complexity solutions for detection, but require soft demappers to deduce the soft bits information contained in each of the received symbols. In this work, we present the ZF and MMSE receiver analysis of a bit interleaved and coded MIMO-OFDM system and propose a soft output demapper based on MMSE equalizer output to demap the information needed for viterbi decoding. A comparison of the proposed soft demapper with conventional soft demappers in literature show a significant performance improvement. We also noticed that it is more advantageous to apply the proposed demapper on a MIMO-OFDM system employing higher modulation schemes.

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“…This is in order to satisfy the increasing demand for high data rate communications in frequency selective fading channels. The advantages of OFDM include its ability to mitigate Inter-Symbol Interference (ISI) caused by channel frequency selectivity [1], and its use of simple frequency domain equalizers at the receiver for efficient detection [2], [3]. However, OFDM suffers high Peak to Average Power Ratio (PAPR) which may severely impair system performance due to induced spectral regrowth and detection performance degradation.…”

Section: Introductionmentioning

confidence: 99%

A Generalized Bit Error Rate Evaluation for Index Modulation Based OFDM System

et al. 2020

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Orthogonal frequency division multiplexing (OFDM-IM) is a multicarrier transmission technology that modulates information bits not just onto subcarriers by means of M-ary constellation mapping but also onto selected (active) subcarrier indices. Consequently, errors can occur in OFDM-IM systems indices in addition to the errors of M-ary symbols. This paper analyzes the error scenarios and derives mathematical expressions for the error performance based on the maximum likelihood (ML) detection. In evaluating the bit error rate (BER) in the additive white Gaussian noise (AWGN) channel, some assumptions are made and our analytical result show that the BER of OFDM-IM system is a weighted sum of exponential functions and Q-functions. Our general BER expression has been shown to be in excellent agreement with numerical simulation and proven to be accurate and can serve as a reference for the design and evaluation of any arbitrary size and configuration of OFDM-IM systems.

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A low complexity 256QAM soft demapper for 5G mobile system

Cited by 27 publications

References 9 publications

Output SNR analysis and detection criteria for optimum DCT-based multicarrier system

Output SNR analysis and detection criteria for optimum DCT-based multicarrier system

Performance analysis and soft demapping for coded MIMO-OFDM systems

A Generalized Bit Error Rate Evaluation for Index Modulation Based OFDM System

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