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1

Coded GFDM with decision feedback equaliser for enhanced performance in underwater wireless optical communication

Hema R., Ananthi A., Diana D. C.

Opto-Electronics Review

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2024

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Vol. 32, No. 1

art. no. e148697

EN

Underwater wireless optical communication is the best alternative for many applications especially for high bandwidth data communication between underwater objects and vehicles. The implementation of coding scheme along with advanced modulation technique and equalisation methods is identified as a key research scope for enhancing the performance of the system. In this paper, the coded generalised frequency division multiplexing (GFDM) technology is employed to provide high-data rates and less out-of-band emission. The Bose-Chaudhuri-Hocquenghem (BCH) and Reed-Solomon (RS) coding schemes along with equalisation techniques namely normalised least mean square (NLMS)-based decision feedback equalisers (DFE), minimum mean square error (MMSE) and zero forcing (ZF) are utilized to reduce inter symbol interference (ISI). The bit error rate (BER) performance is evaluated in the presence of pointing error (PE) and turbulence using Monte Carlo channel modelling simulations. The results showed that RS coding with NLMS-DFE outperforms other techniques and achieves a BER of roughly 10⁻⁵ with a signal-to-noise ratio levels below 20 dB. The simulation results demonstrate that RS code with 15 total symbols per code word and 3 data symbols, i.e., RS (15, 3) and BCH code with 31 total symbols in a code word and 6 data symbols, i.e., BCH (31, 6) provided the best error performance among other coding schemes employed. It is inferred that RS (15, 3) coded 2 × 2 multiple input multiple output systems with NLMS-DFE achieved a BER value of 1.1925 × 10⁻⁵ at 11 dB which is 16 dB less than uncoded system. Thus, the coded GFDM improves overall BER performance and has the potential to provide higher reliability for internet of underwater things (IoUT) applications.

2

Recognition of convolutional codes

Nowosielski Leszek, Dudziński Bartosz, Nowosielski Michał, Ślubowska Aleksandra

Przegląd Elektrotechniczny

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2023

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R. 99, nr 7

140--146

EN

Radio communication remains one of the most effective and prevalent methods of communication to date. Therefore, there is a need for tools (such as the Universal Digital Demodulator), which would give the appropriate state services the ability to monitor unknown radio emissions. Un-fortunately, manufacturers of hardware and software for automatic recognition of radio com-munication protocols do not publish the solutions they use, arguing that these solutions are proprietary information. The authors of the article did not find many articles on automatic recognition of convolutional codes in the available literature, and thus propose such a convolu-tional code recognition method, which is one of many components of the radio communication protocol recognition system. The first part of the article contains a short description of the convolutional code decoding process using the Viterbi algorithm. What follows is a presentation of an innovative method of automatic recognition of convolutional code types, based on monitoring of path metrics values during the operation of the Viterbi decoder. Finally, the results of operational efficiency measurements for the proposed algorithm convolutional code recognition algorithm, achieved using computer simulation, are presented.

PL

Łączność radiowa pozostaje jak dotąd jedną z najskuteczniejszych i najbardziej rozpowszechnionych metod komunikacji. Dlatego potrzebne są narzędzia (takie jak Uniwersalny Demodulator Cyfrowy), które dawałyby odpowiednim służbom państwowym możliwość monitorowania nieznanych emisji radiowych. Niestety, producenci sprzętu i oprogramowania do automatycznego rozpoznawania protokołów komunikacji radiowej nie publikują stosowanych przez siebie rozwiązań, twierdząc, że są to informacje zastrzeżone. Autorzy artykułu nie odnaleźli w dostępnej literaturze wielu artykułów dotyczących automatycznego rozpoznawania kodów splotowych, stąd proponują taką metodę rozpoznawania kodu splotowego, która jest jednym z wielu elementów składowych systemu rozpoznawania protokołów komunikacji radiowej. Pierwsza część artykułu zawiera krótki opis procesu dekodowania kodu splotowego z wykorzystaniem algorytmu Viterbiego. Poniżej przedstawiono prezentację innowacyjnej metody automatycznego rozpoznawania typów kodów splotowych, opartej na monitorowaniu wartości metryk ścieżki podczas pracy dekodera Viterbiego. Na koniec przedstawiono wyniki pomiarów efektywności działania proponowanego algorytmu rozpoznawania kodu splotowego, uzyskane za pomocą symulacji komputerowej.

3

Retransmission as a Replacement Forward Error Correction in Noiseless LV Networks used for Narrowband PLC

Kiedrowski Piotr

Journal of Telecommunications and Information Technology

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2020

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nr 2

91--94

EN

The article describes a project concerned with deploying PLC technology in railway light signals. The proposal increases reliability of communication between railway light signals and the railway automation center, relying on frame retransmissions instead of the FEC technique. The paper presents the results of long-term FER measurements performed in a narrowband PLC-based communication system. The said results are used as communication reliability metrics. Deployment of dual channels in order to increase communication reliability is discussed as well, as is eﬃciency of FEC-based convolutional coding. The results are veriﬁed in a real world environment.

4

100 Gb/s Data Link Layer - from a Simulation to FPGA Implementation

Łopaciński Ł., Brzozowski M., Kraemer R., Buechner S., Nolte J.

Journal of Telecommunications and Information Technology

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2016

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nr 1

90--100

EN

In this paper, a simulation and hardware implementation of a data link layer for 100 Gb/s terahertz wireless communications is presented. In this solution the overhead of protocols and coding should be reduced to a minimum. This is especially important for high-speed networks, where a small degradation of efficiency will lower the user data throughput by several gigabytes per second. The following aspects are explained: an acknowledge frame compression, the optimal frame segmentation and aggregation, Reed-Solomon forward error correction, an algorithm to control the transmitted data redundancy (link adaptation), and FPGA implementation of a demonstrator. The most important conclusion is that changing the segment size influences the uncoded transmissions mostly, and the FPGA memory footprint can be significantly reduced when the hybrid automatic repeat request type II is replaced by the type I with a link adaptation. Additionally, an algorithm for controlling the Reed-Solomon redundancy is presented. Hardware implementation is demonstrated, and the device achieves net data rate of 97 Gb/s.

5

Evaluation of wimax admission control algorithms in mobile voip scenarios with batch arrivals and nbldpc fec

Flizikowski A., Przybyszewski M., Hołubowicz W.

Image Processing & Communications

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2013

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Vol. 18, no. 1

45--56

EN

This paper presents results of assessing quality of VoIP conversations in WiMAX networks using the nbLDPC (non-binary Low- Density Parity-Check) FEC in mobility scenarios that are based on the real world terrain charactristics around simulated BS. System under test (SUT) is instrumented with three Call Admission Control (CAC) mechanisms (namely EMAC, ARAC and nsc-ARAC). These algorithms are evaluated against controlling the VBR traffic that comes with burst arrivals. The first algorithm relies on calculating simple exponential weighted moving average (EWMA) of the overall resource consumption whereas the other two ARAC algorithms perform calculations discerning between the new, the ongoing and the finishing connections thus providing more accurate resource estimations (but the ARAC tracks the history of requests as well). In order to evaluate their performance authors rely on a cell-level based simulation environment that relies on the cooperative use of well known simulators - ns2 and Matlab. Previous work in the field is enhanced by improving the fidelity of proposed IEEE 802.16 simulator. Authors demonstrate the influence of increasing number of arrivals per one batch as well as testing the "zero hour" scenario (system saturation). In order to include nbLDPC codes in SUT’s mobile channels, a method called Link-To-System interface (L2S) has been implemented.

6

Ewolucja szybkich sieci szkieletowych w technice DWDM

Ollivier F., Thompson S., Zugano C.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

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2001

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nr 3

191-200

PL

Omówiono zastosowania szybkiej transmisji DWDM w sieciach szkieletowych, które stwarzają możliwość realizacji marzeń o "całkowicie optycznej sieci". Wskazano na nowe techniki, między innymi na nowe światłowody z dyspersją chromatyczną, umożliwiające spełnienie wymagań stawianych przed przyszłymi szybkimi sieciami szkieletowymi.

EN

High speed DWDM transmission over backbone networks, that opens up the possibility of achieving the dream of an "all optical network", is discussed. The article has highlighted the enabling technologies that will make it possible to meet the requirements of future high speed backbone networks.