Increasing the Bandwidth Efficiency in UW-OFDM

Lang, Oliver; Böck, Carl; Huemer, Mario; Hofbauer, Christian

doi:10.1109/ieeeconf44664.2019.9048927

Cited by 4 publications

(5 citation statements)

References 17 publications

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“…Hence, we expect SICNNv2 to be universally applicable for any communication system with system models similar to the system model ( 5) of SC-FDE systems. To demonstrate this claim, we apply SICNNv2 as an equalizer in a UW-OFDM system [51]- [53]. The data transmission in UW-OFDM systems can be modeled as [39], [51], [52] y = HG…”

Section: Bit Error Ratio Performance Of Sicnnv2 For Uw-ofdmmentioning

confidence: 99%

SICNN: Soft Interference Cancellation Inspired Neural Network Equalizers

Baumgartner,

Lang,

Huemer

2024

Trans. Mach. Learn. Comm. Netw.

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In recent years data-driven machine learning approaches have been extensively studied to replace or enhance traditionally model-based processing in digital communication systems. In this work, we focus on equalization and propose a novel neural network (NN-)based approach, referred to as SICNN. SICNN is designed by deep unfolding a model-based iterative soft interference cancellation (SIC) method. It eliminates the main disadvantages of its model-based counterpart, which suffers from high computational complexity and performance degradation due to required approximations. We present different variants of SICNN. SICNNv1 is specifically tailored to single carrier frequency domain equalization (SC-FDE) systems, the communication system mainly regarded in this work. SICNNv2 is more universal and is applicable as an equalizer in any communication system with a block-based data transmission scheme. Moreover, for both SICNNv1 and SICNNv2, we present versions with highly reduced numbers of learnable parameters. Another contribution of this work is a novel approach for generating training datasets for NN-based equalizers, which significantly improves their performance at high signal-to-noise ratios. We compare the bit error ratio performance of the proposed NN-based equalizers with state-of-the-art model-based and NN-based approaches, highlighting the superiority of SICNNv1 over all other methods for SC-FDE. Exemplarily, to emphasize its universality, SICNNv2 is additionally applied to a unique word orthogonal frequency division multiplexing (UW-OFDM) system, where it achieves state-of-theart performance. Furthermore, we present a thorough complexity analysis of the proposed NN-based equalization approaches, and we investigate the influence of the training set size on the performance of NN-based equalizers.

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Section: Bit Error Ratio Performance Of Sicnnv2 For Uw-ofdmmentioning

confidence: 99%

SICNN: Soft Interference Cancellation Inspired Neural Network Equalizers

Baumgartner,

Lang,

Huemer

2024

Trans. Mach. Learn. Comm. Netw.

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“…The encoded bits are interleaved within one UW-OFDM burst. We note that the interleaver length is different compared to an interleaver restricted to one OFDM symbol as utilized in some of our previous works [1], [2], [6], [8], [9], [10], [38], [11], which therefore may impede a direct comparison of the BER results in some cases. However, a change of the interleaver length is necessary to prevent statistical dependencies among the bits within an OFDM symbol l, which are otherwise present due to a common error introduced by the estimate φl , resulting then in a degradation of the decoding performance at the receiver.…”

Section: A Simulation Setupmentioning

confidence: 99%

“…The introduction of the unique word within the discrete Fourier transform (DFT) interval requires the introduction of redundancy in the frequency domain. This redundancy can advantageously be utilized to provide several beneficial properties, such as superior spectral shaping characteristics [2], [3], [4], [5], [6] or outstanding bit error ratio (BER) performance for linear [7], [8], [2], [9], [10], [11], non-linear [12], [13], [14], [15] as well as iterative [16], [17] receivers 1 .…”

Section: Introductionmentioning

confidence: 99%

Impact of a Carrier Frequency Offset on Unique Word OFDM

Hofbauer

Haselmayr

Bernhard

et al. 2020

2020 IEEE 31st Annual International Symposium on Personal, Indoor and Mobile Radio Communications

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Word-orthogonal frequency division multiplexing (UW-OFDM) is known to provide various performance benefits over conventional cyclic prefix (CP) based OFDM. Most important, UW-OFDM features excellent spectral sidelobe suppression properties and an outstanding bit error ratio (BER) performance. Carrier frequency offset (CFO) induced impairments denote a challenging task for OFDM systems of any kind. In this work we investigate the CFO effects on UW-OFDM and compare it to conventional multi-carrier and single-carrier systems. Different CFO compensation approaches with different computational complexity are considered throughout this work and assessed against each other. A mean squared error analysis carried out after data estimation reveals a significant higher robustness of UW-OFDM over CP-OFDM against CFO effects. Additionally, the conducted BER simulations generally support this conclusion for various scenarios, ranging from uncoded to coded transmission in a frequency selective environment.

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“…The introduction of the unique word within the discrete Fourier transform (DFT) interval requires the introduction of redundancy in the frequency domain. This redundancy can advantageously be utilized to provide several beneficial properties, such as superior spectral shaping characteristics [2], [3], [4], [5], [6] or outstanding bit error ratio (BER) performance for linear [7], [8], [2], [9], [10], [11], non-linear [12], [13], [14] as well as iterative [15], [16] receivers 1 .…”

Section: Introductionmentioning

confidence: 99%

“…In this context, spreading redundancy by Tp on (N d + Nr) instead of Nr subcarriers helps reducing the required energy Jp 6. The energy is scaled by N , originating from the DFT, to easier link the resulting energies with the number of pilots Np in the subsequent paragraphs.…”

mentioning

confidence: 99%

On the Inclusion and Utilization of Pilot Tones in Unique Word OFDM

Hofbauer,

Haselmayr,

Bernhard

et al. 2020

Preprint

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Unique word-orthogonal frequency division multiplexing (UW-OFDM) is known to provide various performance benefits over conventional OFDM using cyclic prefixes (CP). Most important, UW-OFDM features excellent spectral sidelobe suppression properties and an outstanding bit error ratio performance. Current research has mainly focused on principle performance bounds of UW-OFDM, with less attention on challenges aside from idealized communication scenarios, such as system parameter estimation tasks. In this work we present an approach for including frequency pilots tones into the UW-OFDM signaling scheme, which can then be utilized for these estimation tasks. Suitable optimization criteria are presented and interactions of pilots with data symbols are highlighted. Pilot tone based estimation of a carrier frequency offset (CFO) is conducted as an estimation example, revealing considerable differences to conventional OFDM. Simulation results in a multipath environment demonstrate a significantly increased estimation accuracy in UW-OFDM over CP-OFDM, which becomes even more dominant with an increasing CFO. This performance difference is due to the inherent redundancy present in an UW-OFDM signal.

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Increasing the Bandwidth Efficiency in UW-OFDM

Cited by 4 publications

References 17 publications

SICNN: Soft Interference Cancellation Inspired Neural Network Equalizers

SICNN: Soft Interference Cancellation Inspired Neural Network Equalizers

Impact of a Carrier Frequency Offset on Unique Word OFDM

On the Inclusion and Utilization of Pilot Tones in Unique Word OFDM

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