Two-dimensional differential demodulation for OFDM

Haas, E.; Kaiser, Stefan

doi:10.1109/tcomm.2003.810831

Cited by 16 publications

(12 citation statements)

References 11 publications

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“…The complexity increases roughly exponentially as 8 · 7 Lmax−1 , so an appropriate algorithm should be created to reduce the amount of investigated paths, rather than using the exhaust method, e.g., brute-force method in [12].…”

Section: B Optimal Path Selection Criterionmentioning

confidence: 99%

“…For 1-D DD or L max = 1, N unit equals one obviously. Compared with the brute-force method in [12], our 2-D DD optimal path searching algorithm has more reasonable complexity, and saves about 86% computational complexity in both channels for L max = 3, which can obtain most of the performance gain. …”

Section: Complexity Comparisonmentioning

confidence: 99%

“…To overcome the degrading effects of differential demodulation (DD), a variety of techniques have been discussed in the literatures [8]- [12]. A suboptimal soft Viterbi decoding metric was used in [8] and [9] to compensate for the SNR gap between 64-QAM and 64-DAPSK.…”

Section: Introductionmentioning

confidence: 99%

“…While [8]- [11] perform the DD in only one dimension (1-D), namely, the direction of the modulated information. Then, as reported in [12], Haas conceived a two-dimensional differential demodulation (2-D DD) that was based on differential quadrature phase shift keying (DQPSK) modulated OFDM signals. However, the suggested algorithm uses the complicated soft decision metric and exhausting method to search for the optimal path, and has not been generalized to DAPSK.…”

Section: Introductionmentioning

confidence: 99%

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Two-Dimensional Differential Demodulation for 64-DAPSK Modulated OFDM Signals

Gong

Han

et al. 2010

2010 7th IEEE Consumer Communications and Networking Conference

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A novel two-dimensional differential demodulation (2-D DD) algorithm, which exploits both the time and frequency dimensions by using the orthogonal frequency division multiplexing (OFDM) frame structure, was investigated for 64-differential amplitude and phase shift keying (DAPSK) modulated OFDM signals. Without changing the transmitter, the proposed algorithm based on graph attempts to search for a more confident bypass, probably containing multiple DD operations, to demodulate one 64-DAPSK symbol rather than conventional direct DD. In order to carry out the optimal path searching process, the soft decision metrics of the amplitude ratio and phase difference were derived by making use of a Gaussian approximation. Simulation results show that the proposed algorithm can obtain substantial performance gains with reasonable computational complexity for uncoded AWGN and frequency selective fading channels. In addition, it is advantageous to withstand the Doppler effect, which is hence suitable for high mobile (e.g., in a car or train) broadband wireless access (BWA) systems.

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Section: B Optimal Path Selection Criterionmentioning

confidence: 99%

Section: Complexity Comparisonmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Two-Dimensional Differential Demodulation for 64-DAPSK Modulated OFDM Signals

Gong

Han

et al. 2010

2010 7th IEEE Consumer Communications and Networking Conference

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“…PSK or quadrature amplitude modulation (QAM) with or without spreading. Similarly to the algorithm presented for differentially coherent systems in [6], it makes use of the two-dimensional (2D) structure of the OFDM frame applied in the multi-carrier code-division multiple access (MC-CDMA) system and uses decisions on neighbouring data symbols to improve the estimate of the current pilot or data symbol.…”

Section: Introductionmentioning

confidence: 99%

Improved MC-CDMA reception employing two-dimensional decision-feedback pilot and data symbol correction

Haas

Krzymien²

Eighth IEEE International Symposium on Spread Spectrum Techniques and Applications - Programme and Book of Abstracts (IEEE Cat.

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In this contribution, an algorithm is presented that recovers to a large degree the performance degradation due to channel estimation and equalization errors in a multi-carrier code division multiple access (MC-CDMA) system. The algorithm uses the two-dimensional structure of the MC-CDMA frame to estimate the equalization error. It contains two steps that can be applied independently from each other. In the first step, the pilot symbols are corrected and channel estimation and equalization is redone for the received data symbol samples. In the second step, a possible remaining mismatch on the equalized data symbol samples is 're-equalized' and new symbol decisions on the 're-equalized' signal are made. It is shown that the algorithm is able to improve the performance in additive white Gaussian noise (AWGN) and fading channels with and without channel coding. On a frequency-selective fading channel and with standard Rcc = 1/2 convolutional coding, a performance improvement of approximately 4.75 dB is possible at a BER of 10 −6 .Index Terms-Multi-carrier code division multiple access, orthogonal frequency division multiplexing, phase shift keying, quadrature amplitude modulation, demodulation, multidimensional signal detection, channel equalization.

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Multi‐Carrier and Spread Spectrum Systems

Fazel¹,

Kaiser²

2008

462

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Two-dimensional differential demodulation for OFDM

Cited by 16 publications

References 11 publications

Two-Dimensional Differential Demodulation for 64-DAPSK Modulated OFDM Signals

Two-Dimensional Differential Demodulation for 64-DAPSK Modulated OFDM Signals

Improved MC-CDMA reception employing two-dimensional decision-feedback pilot and data symbol correction

Multi‐Carrier and Spread Spectrum Systems

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