Michał Hoeft

How to provide fair service for V2I communications in VANETs

In this paper, we focus on fairness issues of Vehicle-to-Infrastructure (V2I) communications. In particular, we show that under a common technique of selection of RSUs by OBUs based on the received signal strength, a vast variability of a number of OBUs connected to RSUs can be observed leading to inefficient/unfair service provided by RSUs.To overcome this problem, we propose an algorithm for RSU selection called RSEL to obtain even attachment of OBUs to RSUs. Its objective is to approach the best solution in terms of minimizing variability of the number of OBUs connected to each RSU and, as a result, increase fairness of access to services in V2I communications. We analyzed five scenarios referring to different RSU location schemes for two VANET topologies: considering urban environment and a multilane highway. As confirmed via simulations, the average fairness of RSU load (based on Jains formula) was improved up to 50%, while the value of user-perspective fairness measure of collision-free transmissions, introduced in this paper, was increased up to 35%.

Comparative Analysis of IP-Based Mobility Protocols and Fast Handover Algorithms in IEEE 802.11 Based WLANs

A rapid growth of IP-based networks and services created the vast collection of resources and functionality available to users by means of an uniform method of access – an IP protocol. At the same time, advances in design of mobile electronic devices allowed them to reach utility level comparable to stationary, desktop computers, while still retaining their mobility advantage. Unfortunately, the base IP protocol does not perform very well in mobile environments, due to lack of handover support and higher layer mobility management mechanisms. In this paper we present an overview of the most popular and promising methods of handling mobility in IPv4 and IPv6 networks, covering both ISO-OSI layer 2 low level handover mechanisms in IEEE 802.11 WLAN systems and ISO-OSI layer 3+ mobility solutions.

A Test-Bed Analysis of Simultaneous PMIPv6 Handover in 802.11 WLANs Environment

Providing mobility in access networks is a challenge that we have to deal with. Due to networks’ convergence and migration to all-IP networks, mobility management at the network layer is required. However, there is a need for cooperation mechanisms between the network layer and lower layers to support multimedia services and make handover more efficient. This paper presents experimental research on simultaneous handover performance in an integrated PMIPv6 and 802.11 WLAN system.

On extending open source IMS platform for integrated IPTV and VoIP services over IPv6

Even when IMS is the most popular platform for multimedia services, the open versions of IMS ecosystem are lacking in specified functionalities for IPTVv6 and VoIPv6 services. In this paper, we extend current client and server open source software in order to provide reliability and security to these multimedia services. As a part of our work the IMS architecture for conferencing system with proposed mechanisms to improve system availability is presented. The monitoring, based on local and remote mechanisms, gives an ability to fast and reliable failures detection. The proposed algorithm also includes load balancing of the original initialized and restored conferencing sessions on the MRF servers. The restoring mechanism relocates conferences with media mixing and management to one of the available media servers. Moreover, we put many efforts on adapting current IPv4-oriented software to IPv6 streaming. The importance of the presented results lie in the impulse offered to the multimedia services over IPv6, which are actually the main hindrance in IPv6 start.

Broadband communication solutions for maritime ITSs: Wider and faster deployment of new e-navigation services

In its initial part, the paper presents an overview of popular technologies and systems currently developed or employed in maritime communication. These solutions are used to provide both ship-to-ship and ship-to-shore communication for the purpose of supporting specific services, often dedicated to maritime safety and e-navigation. Utility of such communication systems have been thoroughly verified over the years and their strengths and limitations are also widely known. The later include relatively low maximum throughput and/or high cost of both deployment and operation, caused by the requirement of long communication range and high reliability in difficult propagation conditions. Based on the above overview, the subsequent part of the paper presents preliminary results of research conducted at the Computer Communications Department, Faculty of Electronics, Telecommunications and Informatics, Gdansk University of Technology within the netBaltic project. The projects objective is to create a maritime communication system, able to transparently utilize various transmission technologies to form a multihop network structure and thus provide maritime vessels with Internet Protocol-based communication capabilities in diverse set of conditions and areas. For this purpose a combination of mobility management, mesh and delay tolerant network mechanisms is employed, allowing deployment of a wide range of user-level services, starting with general purpose Internet access, through navigation/weather charts distribution and ending with varied e-navigation functionalities.

netBaltic System – Heterogeneous Wireless Network for Maritime Communications

Abstract In case of maritime communications, we observe a growing interest in deployment of multitask satellite-based solutions and development of new maritime-specific systems intended for improvements in safety of e-navigation. Analysis of different types of currently used maritime communication systems leads, however, to a conclusion that neither global and still very expensive satellite systems nor cheaper, but short-ranged transmission technologies can, on their own, fully meet the today’s expectations and quality requirements formulated for broadband maritime systems. This lack of reliable solutions, offering high throughput and ubiquitous availability of coverage to a wide audience at a relatively low price is one of the main barriers in a widespread implementation of e-navigation initiatives. This issue is addressed in the netBaltic project with the objective to design, deploy and validate in a real maritime environment a non-satellite wireless communication system enabling ship-to-ship and ship-to-shore information exchange via a multi-hop network composed of onshore base stations, maritime vessels and other transit elements such as buoys. In this paper, the idea of a heterogeneous wireless maritime system is presented. Details of the proposed netBaltic node architecture are described highlighting the solutions introduced in the project as a response to specific maritime communication requirements. Numerical results of communication area coverage are presented for four different scenarios utilizing different wireless transmission technologies. In particular, they indicate that when using appropriate wireless communication solutions, the number of vessels being able to connect to Internet is significantly increased as compared to traditional wireless systems (capable of one-hop communication) from 14% for short-range transmission technologies up to as high as 127% in case when relatively long-range transmission technologies are employed within the system.

A heterogenous wireless system for maritime communication - the netBaltic system architecture

In the article, the concept of a heterogeneous wireless maritime mesh network offering transmission for e.g., e-navigation services is presented. The constrains of existing and competitive solutions are discussed showing the need for a new system. The authors present detailed information about a netBaltic nodes architecture and networking mechanisms offering different transmission capabilities and proposed for use on different sea areas. Moreover, the results of the performed measurements campaigns are presented to estimate operational ranges of the described system and its ability to meet the requirements of e-navigation services. Practical advantages of presented solutions are highlighted bringing out new possibilities in e-navigation.

Postępy w rozwoju standardu IEEE 802.11 i jego zastosowańCzęść II: Nowe obszary zastosowań i nowe koncepcje pracy sieci WiFi

Artykul stanowi kontynuacje rozwazan, podjetych w zeszycie nr 11 z 2016 r. PTiWT [1], na temat rozwoju standardu lEEE 802.11 , ukierunkowanego na zwiekszanie szybkości przekazu i przekraczanie gigabitowej granicy przeplywności lącza. Wskazano tam na modyfikacje i nowe mechanizmy implementowane w warstwie fizycznej i podwarstwie MAC standardow IEEE 802.11 n, IEEE 802.11 ac oraz IEEE 802.11 ad, mające istotny wplyw zarowno na wzrost szybkości transmisji, jak i na poprawe efektywności pracy sieci WLAN. W niniejszym artykule skoncentrowano sie na prezentacji najnowszych rozszerzen standardu IEEE 802.11, podstawy bardzo popularnej techniki WiFi, zorientowanych na nowe obszary zastosowan. Przedmiotem zainteresowania są tym razem rozwiązania IEEE 802.11 af (transmisja z uzyciem niewykorzystywanych przedzialow licencjonowanych pasm czestotliwości), IEEE 802.11 af (systemy automatyki oraz komunikacja M2M) oraz IEEE 802.11 P (komunikacja miedzypojazdowa) . Slowa kluczowe: WiFi, radio kognitywne, M2M, sieci samochodowe, IEEE 802.11ah, IEEE802.11af, IEEE802.11p

Evaluation of Connectivity Gaps Impact on TCP Transmissions in Maritime Communications

Many organizations and research working groups, including among others IEEE, ITU, ETSI and IMO are currently working towards improvements in communication of different types of vehicles (cars, trains, planes and vessels) and upgrading utilities and services offered to their crews and passengers travelling all over the world. The paper deals with selected aspects of the TCP protocol connectivity in maritime wireless networks. The authors show results of measurements performed in a real-world maritime environment consisting of on- and off-shore devices and transmission systems, partly located on vessels. Based on the collected measurements, the authors provide statistical analysis, including connectivity periods and connectivity gaps observed as a result of vessels motions. The obtained statistical results were used, in turn, in a simulation test-bed to verify efficiency of TCP connections, assuming the use of Reno algorithm, together with F-RTO enhancement (Forward RTO-Recovery), Cubic algorithm, and further adjustments proposed by the authors. The results show significant increase of the average throughput (up to 3 times) and decrease of the average download time (up to 53%), as compared to the pure Reno TCP solution. The proposed modifications seem to be especially important and attractive for highly unreliable wireless links - expected to be very common in a maritime environment.

netBaltic – heteregeniczny system bezprzewodowej łączności na Morzu Bałtyckim

W artykule przedstawiono podstawowe zalozenia dotyczące realizacji systemu heterogenicznej samoorganizującej sie sieci bezprzewodowej zapewniającej lącznośc na obszarze morskim, miedzy innymi na potrzeby uslug e-nawigacji. Wskazano na ograniczenia istniejących systemow, w tym systemow satelitarnych, pokazując jednocześnie potrzebe opracowania nowego rozwiązania. Autorzy przedstawili dedykowane mechanizmy i systemy o zroznicowanych mozliwościach transmisji danych proponowane do wykorzystywania na roznych obszarach morza. Szczegolną uwage zwrocono na praktyczne korzyści plynące z proponowanego systemu w postaci nowych mozliwości wdrazania uslug e-nawigacji oraz uslug akwizycji i szybkiego transferu roznych typow danych.