Jozef Wozniak

Performance Analysis of Multicast Video Streaming in IEEE 802.11 b/g/n Testbed Environment

The aim of the work is to analyse capabilities and limitations of different IEEE 802.11 technologies (IEEE 802.11 b/g/n), utilized for both multicast and unicast video streaming transmissions directed to mobile devices. Our preliminary research showed that results obtained with currently popular simulation tools can be drastically different than these possible in real-world environment, so, in order to correctly evaluate performance of video streaming, a simple wireless test-bed infrastructure has been created. The results show a strong dependence of the quality of video streaming on the chosen transmission technology. At the same time there are significant differences in perception quality between multicast (1:n) and unicast (1:1) streams, and also between devices offered by different manufacturers. The overall results seem to demonstrate, that, while multicast support quality in different products is still varied and often requires additional configuration, it is possible to select a WiFi access point model and determine the best system parameters to ensure a good video transfer conditions in terms of acceptable QoP/E (Quality of Perception/Exellence).

Performance of mobility support mechanisms in a heterogeneous UMTS and IEEE 802.11 network offered under the IEEE 802.21 standard

Wireless networks are becoming increasingly popular. These wireless solutions range from personal networks (e.g. Bluetooth), through local (e.g. WiFi) and metropolitan area networks (e.g. WiMax) up to the cellular networks that offer the coverage almost everywhere. As the number of different wireless technologies grows, a unified and standardized mobility support algorithm for heterogeneous networks is needed. The paper evaluates the performance of mobility support mechanisms and algorithms offered by a new IEEE 802.21 standard. The heterogeneous scenario with UMTS and IEEE 802.11 networks is modeled and investigated. The handover in both directions is discussed, taking into account implementation of MIH Link Going Down event for IEEE 802.11 networks, proposed by the authors. This event is used to optimize handover from IEEE 802.11 network to UMTS networks. The new, proposed in the paper solution, makes it possible to support multimedia services during the heterogenous handovers. To verify the proposed algorithm the simulation environment has been defined, based on ns-2 simulator. The number of experiments was performed to evaluate the packets lost ratio and the delays introduced by heterogenous handover.

Wireless and Mobile Networking

This book constitutes the refereed proceedings of the Second IFIP WG 6.8 Joint Conference on Wireless and Mobile Networking, WMNC 2009, held in Gdansk, Poland, in September 2009. The 30 thoroughly revised papers presented together with one invited talk were selected from 65 submissions. The papers are evenly split among three tracks: Personal Wireless Communications (PWC), Wireless Sensor and Actors Networks (WSAN) and Mobile and Wireless Communications Networks (MWCN) reflecting the state of the art, current discussions, and development trends in wireless and mobile networks and services. They are divided in topical sections on IMS interoperability; QoS and multimedia support; network design; sensor networks; trust management and competitive networking; location algorithms; evolution of 3G, 3G/4G and future generation systems; and handover mechanisms.

Analysis of IPv6 handovers in IEEE 802.16 environment

The second generation of WiMAX solutions, based on IEEE 802.16-2005 standard, offers limited mobility support. Unfortunately, after quickly changing the point of attachment on the WiMAX data link layer (DLL), very slow and inefficient IPv6 reconfiguration takes place. Delays introduced by automatic configuration (DHCPv6 and IPv6 protocols) and Mobile IPv6 can easily diminish or even render useless all benefits gained using the efficient handover performed on DLL. As handover is a crucial process in mobile cellular environments, reasons behind delays introduced by IPv6 layer mechanisms have to be analyzed and appropriate countermeasures applied.In order to analyse influence of different factors on the handover delay a simulation environment modelling the full handover procedure in a WiMAX environment has been developed. It allows simulation and analysis of various mobility related issues, offering support for multiple base stations with groups of subscribers, both fixed and mobile, with various mobility models. Also support for tight integration with higher layers (IPv6, DHCPv6, and Mobile IPv6) is fully implemented. All stages of full IPv6 handover in IEEE 802.16 environment, focusing on major reasons of reconfiguration delays are described.The paper presents components, functional requirements and architecture of the simulation environment, together with example simulation results. The obtained results clearly show that most significant delays are caused by the IPv6 layer. The areas of improvement in several autoconfiguration mechanisms are identified. Proposals include novel use of DHCPv6 relays for remote configuration, solving DAD delays, limiting Binding Update procedure in Mobile IPv6, and configuring routing through DHCPv6 communication.A universal metric for assessing impact of every stage on handover efficiency is also defined. Several proposed improvements to the IPv6 handover process are evaluated. Discussion regarding possible generalization of best improvement proposals and remarks on further research areas conclude this paper.

Analysis of profitability of inter-system handovers between IEEE 802.11b and UMTS

Internet access using relatively fast wireless local area networks (WLANs) is often perceived as a local complement to slower, but widely available access using cellular networks, e.g. GSM/GPRS or UMTS. To benefit from the advantages offered by both radio access networks, a mobile user should be able to seamlessly change the access network while moving, experiencing temporary network congestions or whenever switching to the other network seems profitable. The goal of this paper is to analyse the profitability of performing vertical handovers between IEEE 802.11b and UMTS in case of using mobile IPv4. Such research has not yet been done in detail before. The profitability of performing vertical handovers has been analysed depending on the available UMTS channel bandwidth, channel quality, number of WLAN users and generated traffic type. Several detailed simulations have been carried out using NS2 and results are presented. Based on these results, a general criterion for profitable switching between UMTS and IEEE 802.11b is proposed, analysed and verified by simulations.

On the fast BSS transition algorithms in the IEEE 802.11r local area wireless networks

Handover performance is critical to support multimedia services that are becoming increasingly available over the wireless devices. The high transition delay can be unaccepted for such services or can be a source of disruption on the session. On the other side, IEEE 802.11 standard is being extended with new functionalities. Security and QoS features, included in recent IEEE 802.11-2007 standard, add management frames that are exchanged during the transition process. In consequence the handover delay is increased. IEEE 802.11r-2008 amendment introduces Fast BSS Transition (FT) that simplifies the handover process. The authors propose the new handover algorithms based on FT protocol and compare them with existing solution. Additionally, simulation experiments are conducted to answer the question if multimedia services can be properly supported in IEEE 802.11r networks. The authors prove that handover delay can be reduced to 13 ms in the average case.

Mobility management solutions for IP networks

A rapid growth of IP-based networks and services has created a vast collection of resources and functionalities available to users by means of a uniform method of access offered by the IP protocol. At the same time, advances in the design of mobile electronic devices allowed them to reach a utility level comparable to 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 IP networks, covering ISO-OSI layers 2+, 3, as well as layer 3+ and layers 4 and 7 of mobility solutions, together with newly proposed methods.

Extension Management of a Knowledge Base Migration Process to IPv6

There are many reasons to deploy IPv6 protocol with IPv4 address space depletion being the most indisputable. Unfortunately, migration to the IPv6 protocol seems slower than anticipated. To improve pace of the IPv6 deployment, authors of the article developed the two applications -- IPv6 Migration Guide and IPv6 Knowledge Builder -- that support the migration process. Their main purpose of both applications is to help less experienced network administrators facilitate the migration process. Even though both application are generic in principle, they are focusing on enabling IPv6 in SOHO networks at this stage of development. This paper presents IPv6 Migration Guide with detailed description of available network detection techniques. A prototype of IPv6 Knowledge Builder application, its design concepts, intended usage scenarios and development details are also presented. It will allow extending existing knowledge base by defining new knowledge entities (questions, answers, advices and tests) to IPv6 Migration Guide in an easy manner. Used together with already developed IPv6 Migration Guide tool, it will provide significant assistance to network administrators during IPv6 enabling phase.

A new role-switching mechanism optimizing the coexistence of bluetooth and Wi-Fi networks

Unlicensed ISM band is used by various wireless technologies. Therefore, issues related to ensuring the required efficiency and quality of operation of coexisting networks become essential. The paper addresses the problem of mutual interferences between IEEE 802.11b transmitters (commercially named Wi-Fi) and Bluetooth (BT) devices. An optimization approach to modeling the topology of BT scatternets is introduced, resulting in more efficient utilization of ISM environment consisting of BT and Wi-Fi networks. To achieve it, the Integer Linear Programming approach has been proposed. Example results presented in the paper illustrate significant benefits of using the proposed modeling strategy.

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.