2023. 1^st Issue

Volume XV, Number 1

Table of contents 

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MESSAGE FROM THE EDITOR-IN-CHIEF

Pal Varga
Recent advances on high performance computing, mobile networking, and security
WITH the advent of new generation large language modelbased tools, such as ChatGPT, many worktasks and positions must re-evaluate themselves. This applies to writing editorial messages as well. It is no secret: I am using Google for searching scientific articles. Similarly: I used ChatGPT to extract some key information of the articles in this issue. The result needed validation and verification (just like Google search results), and some re-writing from my side – but the world has changed. Hopefully for the better, even for the long term! 

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PAPERS FROM OPEN CALL

Hayder Almizan, Marwah Haleem Jwair, Yahiea Al Naiemy, Zaid A. Abdul Hassain, Lajos Nagy and Taha A. Elwi
Novel Metasurface based Microstrip Antenna Design for Gain Enhancement RF Harvesting 
This paper presents an enhancement in radio frequency (RF) harvesting for conventional patch antenna using a metasurface layer (MSL). The key point behind such enhancement is inspired by Friis’ equation which states; increasing the antenna gain leads to an increase in the received power. To achieve this goal, a MSL consists of 5×5-unit cells of a modified Jerusalem cross are proposed. The proposed MSL provides gain enhancement of about 10 dBi while the gain of the patch antenna is about 1 dBi. The proposed MSL is fabricated, compacted to the antenna and experimentally characterized. The empirical results indict an excellent agreement with the numerical results in terms of |S11| and radiation patterns. In addition, a set of RF harvesting measurements are made for patch antenna with and without the MSL. The comparison between measurements shows a significant enhancement in the output voltage when the MSL is involved.

Reference
DOI: 10.36244/ICJ.2023.1.1
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Zoltán Belső and László Pap
On the Convex Hull of the Achievable Capacity Region of the Two User FDM OMA Downlink 
In multiple access channel systems, such as a mobile communication network, it is important to determine how to share the available resources (for example bandwidth and power) among the users. In recent years, one of the promising scheme is Non-Orthogonal Multiple Access (NOMA), where, unlike the traditional Orthogonal Multiple Access, OMA solution, signals for the different users overlap in some domain (power-domain NOMA, code-domain NOMA, etc). In order to evaluate the performance of any NOMA scheme, we need to compare the achievable bit rates of the users (the capacity region) to an OMA case with comparable parameters (for example, same total bandwidth, same total power and same channel conditions, etc). To make this comparison, we first need to know the capacity region for the OMA cases. Many papers make such comparison without detailing the derivation of the capacity region of the OMA case they compare to [1], [2], [3], [4]. In some cases, we have only one free parameter to choose (for example in uplink frequency division multiplexing systems for two users, it is the bandwidth ratio between the users), and the achievable capacity can be directly calculated for both users depending on the single parameter (hence the boundary of the capacity region is trivial). In other cases, such as downlink frequency division multiplexing systems, even for only two users, we have to allocate optimally two resources between the users: the bandwidth and the base station’s available power. Hence, it is far from being trivial to determine which combination is better and where the boundary of the capacity region is. In this paper, we provide a derivation for that case. 

Reference
DOI: 10.36244/ICJ.2023.1.2
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András Béres and Bálint Gyires-Tóth
Enhancing Visual Domain Randomization with Real Images for Sim-to-Real Transfer 
In order to train reinforcement learning algorithms, a significant amount of experience is required, so it is common practice to train them in simulation, even when they are intended to be applied in the real world. To improve robustness, camerabased agents can be trained using visual domain randomization, which involves changing the visual characteristics of the simulator between training episodes in order to improve their resilience to visual changes in their environment. In this work, we propose a method, which includes realworld images alongside visual domain randomization in the reinforcement learning training procedure to further enhance the performance after sim-to-real transfer. We train variational autoencoders using both real and simulated frames, and the representations produced by the encoders are then used to train reinforcement learning agents. The proposed method is evaluated against a variety of baselines, including direct and indirect visual domain randomization, end-to-end reinforcement learning, and supervised and unsupervised state representation learning. By controlling a differential drive vehicle using only camera images, the method is tested in the Duckietown self-driving car environment. We demonstrate through our experimental results that our method improves learnt representation effectiveness and robustness by achieving the best performance of all tested methods. 

Reference
DOI: 10.36244/ICJ.2023.1.3
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Norman Bereczki and Vilmos Simon
Machine Learning Use-Cases in C-ITS Applications 
In recent years, the development of Cooperative Intelligent Transportation Systems (C-ITS) have witnessed significant growth thus improving the smart transportation concept. The ground of the new C-ITS applications are machine learning algorithms. The goal of this paper is to give a structured and comprehensive overview of machine learning use-cases in the field of C-ITS. It reviews recent novel studies and solutions on CITS applications that are based on machine learning algorithms. These works are organised based on their operational area, including self-inspection level, inter-vehicle level and infrastructure level. The primary objective of this paper is to demonstrate the potential of artificial intelligence in enhancing C-ITS applications.

Reference
DOI: 10.36244/ICJ.2023.1.4
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Ákos Leiter, Edina Lami,  Attila Hegyi, József Varga and László Bokor
Closed-loop Orchestration for Cloud-native Mobile IPv6 
With the advent of Network Function Virtualization (NFV) and Software-Defined Networking (SDN), every network service type faces significant challenges induced by novel requirements. Mobile IPv6, the well-known IETF standard for network-level mobility management, is not an exemption. Cloud-native Mobile IPv6 has acquired several new capabilities due to the technological advancements of NFV/SDN evolution. This paper presents how automatic failover and scaling can be envisioned in the context of cloud-native Mobile IPv6 with closed-loop orchestration on the top of the Open Network Automation Platform. Numerical results are also presented to indicate the usefulness of the new operational features (failover, scaling) driven by the cloud-native approach and highlight the advantages of network automation in virtualized and softwarized environments.

Reference
DOI: 10.36244/ICJ.2023.1.5
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Gábor Lencse, Keiichi Shima
Optimizing the Performance of the Iptables Stateful NAT44 Solution 
The stateful NAT44 performance of iptables is an important issue when it is used as a stateful NAT44 gateway of a CGN (Carrier-Grade NAT) system. The performance measurements of iptables published in research papers do not comply with the requirements of RFC 2544 and RFC 4814 and the usability of their results has serious limitations. Our Internet Draft has proposed a benchmarking methodology for stateful NATxy (x, y are in {4, 6}) gateways and made it possible to perform the classic RFC 2544 measurement procedures like throughput, latency, frame loss rate, etc. with stateful NATxy gateways using RFC 4814 pseudorandom port numbers. It has also defined new performance metrics specific to stateful testing to quantify the connection setup and connection tear down performance of stateful NATxy gateways. In our current paper, we examine how the performance of iptables depends on various settings, and also if certain tradeoffs exist. We measure the maximum connection establishment rate, throughput and tear down rate of iptables as well as its memory consumption as a function of hash table size always using 40 million connections. We disclose all measurement details and results. We recommend new settings that enable network operators to achieve significantly higher performance than using the traditional ones. 

Reference
DOI: 10.36244/ICJ.2023.1.6
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Basma Mostafa, Miklos Molnar, Mohamed Saleh, Abderrahim Benslimane and Sally Kassem
Dynamic Distributed Monitoring for 6LoWPAN-based IoT Networks 
Mission-criticalal Internet of Things (IoT)-based networks are increasingly employed in daily and industrial infrastructures. The resilience of such networks is crucial. Given IoT networks’ constantly changing nature, it is necessary to provide dependability and sustainability. A robust network monitoring can reinforce reliability, such that the monitoring mechanism adapts itself to real-time network instabilities. This work proposes a proactive, dynamic, and distributed network monitoring mechanism with monitor placement and scheduling for 6LoWPAN-based IoT networks intended for mission-critical applications. The proposed mechanism aims to ensure real-time monitoring coverage while respecting the limited and changing power resources of devices to prolong the network lifetime.

Reference
DOI: 10.36244/ICJ.2023.1.7
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Péter Orosz, Tamás Skopkó, Tamás Marosits
Application-Aware Analysis of Network Neutrality: A Scalable Real-Time Method 
Internet access subscribers expect a satisfying quality of experience for any accessed service, independently from time, place, and service- and content-type. Besides the everincreasing amount of Internet data, the spectrum of video service platforms offering sharing and streaming also got significantly more comprehensive. Internet access providers try to avoid the exhaustion of network bandwidth by investing in network capacity or setting up higher-level resource management within their infrastructure. The primary question in this domain is how resource management constrains the subscriber to access an arbitrary service and experience good service quality.This question directly relates to network neutrality fundamentals. This paper presents a real-time full-reference objective method to assess network neutrality. It contributes three novelties to support user-centric analysis of potential restraints affecting Internet access quality: i) the proposal supports application-specific measurements and involves real content and real traffic, ii) the measured traffic originates from the content provider’s cloud infrastructure, iii) reference is created in real time. Accordingly, the proposal introduces a novel measurement layout. The key component is the emulated client that provides the real-time reference by emulating the access properties of the real client and accessing the same content simultaneously. We demonstrate the method’s feasibility with an applicationaware proof-of-concept use case: video streaming from a public VoD provider. We have validated the method against the emulated network parameters using an extensive series of laboratory measurements.

Reference
DOI: 10.36244/ICJ.2023.1.8
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Gábor Földes
Techno-economic analysis on Mobile Network Sharing contribution to social welfare at 4G-5G area in Hungary 
Telecommunication sector faces to parallel investments into both fixed and mobile (5G) networks, however return on investments lag behind profit expectations. Co-investment, like mobile network sharing is a cost efficiency enabler that may accelerate price decrease, may allow earlier, higher coverage and may improve capacity and quality parameters, like download speed, therefore altogether contributes to social welfare increase. The purpose of this paper to assess the Hungarian mobile network sharing that not cleared by the competition regulator, however has been placed in unchanged form for 8 years. The research question is to assess what is the connection between mobile network sharing and social welfare improvement at 4G - 5G mobile broadband rollout. The finding is that, majority of network sharing procompetitive effects allowing benefits, but anticompetitive effects not causing marked distortion. Affordable connectivity prices for information society roots in operators’ cost efficiency, however further research required to assess proper level of efficiency gains pass through to customers and appropriate level of access pricing to shared infrastructure for other rival operators in Hungary. Mobile Network Sharing’s benefits may outweigh potential drawbacks, but due to lack of regulatory clearance, 5G rollout launched without sharing, causing social welfare loss. The originality of the empirical research is despite network sharing not cleared, procompetitive advantages may outweigh anticompetitive ones.

Reference
DOI: 10.36244/ICJ.2023.1.9
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