SISO Decoding of Z4 Linear Kerdock and Preparata Codes

Some nonlinear codes, such as Kerdock and Preparata codes, can be represented as binary images under the Gray map of linear codes over rings. This paper introduces MAP decoding of Kerdock and Preparata codes by working with their quaternary representation (linear codes over Z4 ) with the complexity of O(N2log2N), where N is the code length in Z4. A sub-optimal bitwise APP decoder with good error-correcting performance and complexity of O(Nlog2N) that is constructed using the decoder lifting technique is also introduced. This APP decoder extends upon the original lifting decoder by working with likelihoods instead of hard decisions and is not limited to Kerdock and Preparata code families. Simulations show that our novel decoders significantly outperform several popular decoders in terms of error rate

Short Block-length Codes for Ultra-Reliable Low-Latency Communications

This paper reviews the state of the art channel coding techniques for ultra-reliable low latency communication (URLLC). The stringent requirements of URLLC services, such as ultra-high reliability and low latency, have made it the most challenging feature of the fifth generation (5G) mobile systems. The problem is even more challenging for the services beyond the 5G promise, such as tele-surgery and factory automation, which require latencies less than 1ms and failure rate as low as $10^{-9}$. The very low latency requirements of URLLC do not allow traditional approaches such as re-transmission to be used to increase the reliability. On the other hand, to guarantee the delay requirements, the block length needs to be small, so conventional channel codes, originally designed and optimised for moderate-to-long block-lengths, show notable deficiencies for short blocks. This paper provides an overview on channel coding techniques for short block lengths and compares them in terms of performance and complexity. Several important research directions are identified and discussed in more detail with several possible solutions.Comment: Accepted for publication in IEEE Communications Magazin

Simulations in explosive processes area

Saglasnost teorije i eksperimenata eksplozivnih procesa pripada kategorijama kod kojih se traži visoka pouzdanost. Eksperimenti sa daljinskom kontrolom ili izazivanjem detonacionih procesa predstavljaju jednu od oblasti u kojoj se primenom optičkih metoda može da smanji rizik povezan sa ljudskim faktorom. Simulacije dinamike kad će pojedini zaštitini materijal da dostigne kritične parametre donose razne aproksimacije. U zavisnosti od primene bira se strožiji kriterijum. U radu je data analiza nekih primena lasera u svrhe eksplozivih procesa. Daće se aspekti preplitanja odnosa laser-eksplozivni proces sa nekoliko strana. Analiziraće se neki softverski paketi, kojima se modeluju procesi u kojima laser dovodi do promene temperature lokalnog suda sa eksplozivnim materijalom. Izborom osnovnih jednačina jednog prilaza daju se rezultati temperaturnih polja. Proračun može da posluži kao metod za modelovanje i nalaženje potrebnih uslova rada lasera za obezbeđenje eksplozivnog procesa.The agreement between theory and experiments of explosive processes belongs to a category at which the high reliability is needed. Experiments with remote control and initiation of detonation processes represent such field in which the risk for human factor could be decreased if optical methods are applied. Simulations in dynamics of reaching the critical parameters for different protective materials bring a various approximations. Depending from the application, the stronger criteria could be chosen. The application of some lasers for an explosive process is analyzed in this paper. The interrelations between laser-explosive process will be analyzed from a few sides. Some software packages, for modeling the processes in which the laser brings temperature changes into the container with an explosive material, will be critically analyzed. By choosing the principal equations in one approach, the results of temperature field distribution are given. This calculation may serve as method for modeling and finding the needed conditions of laser action for successful providing an explosive process

Određivanje performansi dekodera zaštitnih kodova

This thesis contains some of the results obtained by the author in the course of his postgraduate research in the fields of Communication system modeling and Information and coding theory. The results are presented in mathematical form and are verified by numerical simulations. Most of them are motivated by challenges arising in the design and standardization of 5G communication systems and are of practical and scientific relevance. Main contributions of the thesis are divided into two parts. In the first part of this thesis we introduce a novel SNR-invariant quasi-analytical technique for estimating the error rate of a communication link over the geodesic channel. We compared this technique to the Monte Carlo and Importance Sampling methods and it has been found out that it outperforms other methods in both accuracy and speed. In the second part of the thesis we introduce an optimization procedure, based on the variable force repulsion method, for the design of spherical codes that are tailored to the TCM and achieve lower error rates at high SNR, then their counterparts that are optimized for minimum distance. The performance of these codes is verified using the method developed in part I of this thesis which is suitable for simulating error rates at high SNR.Ова дисертација садржи неке од резултата аутора добијених током његовог постдипломског истраживања у областима моделовања комуникационих система и теорије информација и заштитног кодовања. Резултати су представљени у математичком формату и верификовани су нумеричким симулацијама. Већина њих је мотивисана проблемима који се појављују приликом развоја и стандрадизације 5G комуникационих система и имају велики научни и практични значај. Дисертација је подељена у два дела. Први део уводи нови квазианалитички поступак за естимацију вероватноће грешке декодера заштитних кодова. Математички је показано и експериментално потврђено да је нови симулациони поступак значајно брзи од постојећих симулационих постпупака (монте карло и поступак узорковања по значајности) који се користе у пракси. У другом делу тезе представљен је проблем конструкције вишедимензионалне трелис кодоване модулације (енг. Trellis Coded Modulation - TCM) помоћу сферичних кодова. Развијен је нови алгоритам за конструкцију сферичних кодова који су прилагођени структури TCM кода и показано је да такви TCM кодови имају знатно боље перформансе од постојећих. Вероватноћа грешке ових нових TCM кодова је естимирана применом симулационог поступка који је дат у првом делу дисертације.Ova disertacija sadrži neke od rezultata autora dobijenih tokom njegovog postdiplomskog istraživanja u oblastima modelovanja komunikacionih sistema i teorije informacija i zaštitnog kodovanja. Rezultati su predstavljeni u matematičkom formatu i verifikovani su numeričkim simulacijama. Većina njih je motivisana problemima koji se pojavljuju prilikom razvoja i standradizacije 5G komunikacionih sistema i imaju veliki naučni i praktični značaj. Disertacija je podeljena u dva dela. Prvi deo uvodi novi kvazianalitički postupak za estimaciju verovatnoće greške dekodera zaštitnih kodova. Matematički je pokazano i eksperimentalno potvrđeno da je novi simulacioni postupak značajno brzi od postojećih simulacionih postpupaka (monte karlo i postupak uzorkovanja po značajnosti) koji se koriste u praksi. U drugom delu teze predstavljen je problem konstrukcije višedimenzionalne trelis kodovane modulacije (eng. Trellis Coded Modulation - TCM) pomoću sferičnih kodova. Razvijen je novi algoritam za konstrukciju sferičnih kodova koji su prilagođeni strukturi TCM koda i pokazano je da takvi TCM kodovi imaju znatno bolje performanse od postojećih. Verovatnoća greške ovih novih TCM kodova je estimirana primenom simulacionog postupka koji je dat u prvom delu disertacije

Development of a Business Model by Introducing Sustainable and Tailor-Made Value Proposition for SME Clients

Due to the combination of vast technology trends brought by Industry 4.0, present-day consumers need and stiff global competition and require businesses from across many industries to constantly innovate. Clients request multifaceted support from manufacturers and service providers while the transition towards new symbiotic ecosystems disrupts traditionally established processes in some sectors. This is largely happening in the global automotive industry where in-car and around-the-car services with asset-sharing concepts are taking a dominant role rather than plain vehicles sales and car ownership. In our paper, we investigate the possibilities of new and improved business collaborations between a car retailer operating in several European countries and its SME (small and medium-sized enterprises) customers across various sectors currently owning car fleets of at least five vehicles. We test several hypotheses and conduct a systematic statistical analysis of the proposed business model’s aspects on the sample of almost 200 SMEs from five countries in Southeast Europe. By using the χ2 test and a one-tailed t-test we tested both frequency data and the continuous variables. Research indicates that SMEs look for new ways to organize their fleet management strategy more efficiently and thus more precisely plan associated costs. Regardless of the country of origin, SMEs want to explore a business model with more introduced to their fleet management and are ready to accept new technologies for fleet management operations