Multipoint Relay Selection based on Stability of Spatial Relation in Mobile Ad hoc Networks

Increasing stability is one of the main objectives in designing routing protocols for Mobile Ad-Hoc Network (MANETS). Various research schemes have been addressed to this challenge and to support it. In fact, some papers have considered modifications to MPRs selection mechanism in OLSR. In this paper, the author proposes a new mechanism to elect stable and sustainable nodes relay between all nodes in MANETs. In this mechanism, a mobility function is used as the main selection criterion based on the calculation of the spatial relation of a node relative to its neighbor. This mechanism is applied in OLSR protocol to choose stable and supportable MPRs nodes. This mechanism significantly finds more stable MPRs and it promises QoS metrics such as lost packets and delay. Simulation results reveals a significant performance gains and it motivates further examinations to develop the mechanism in order to improve the routing protocol requirements. Performances are evaluated based on Random Waypoint model and network simulator ns3

Formulation, implementation considerations, and first performance evaluation of algorithmic solutions - D4.1

Deliverable D4.1 del projecte Europeu OneFIT (ICT-2009-257385)This deliverable contains a first version of the algorithmic solutions for enabling opportunistic networks. The presented algorithms cover the full range of identified management tasks: suitability, creation, QoS control, reconfiguration and forced terminations. Preliminary evaluations complement the proposed algorithms. Implementation considerations towards the practicality of the considered algorithms are also included.Preprin

Joint relay selection and bandwidth allocation for cooperative relay network

Cooperative communication that exploits multiple relay links offers significant performance improvement in terms of coverage and capacity for mobile data subscribers in hierarchical cellular network. Since cooperative communication utilizes multiple relay links, complexity of the network is increased due to the needs for efficient resource allocation. Besides, usage of multiple relay links leads to Inter- Cell Interference (ICI). The main objective of this thesis is to develop efficient resource allocation scheme minimizes the effect of ICI in cooperative relay network. The work proposed a joint relay selection and bandwidth allocation in cooperative relay network that ensures high achievable data rate with high user satisfaction and low outage percentage. Two types of network models are considered: single cell network and multicell network. Joint Relay Selection and Bandwidth Allocation with Spatial Reuse (JReSBA_SR) and Optimized JReSBA_SR (O_JReSBA_SR) are developed for single cell network. JReSBA_SR considers link quality and user demand for resource allocation, and is equipped with spatial reuse to support higher network load. O_JReSBA_SR is an enhancement of JReSBA_SR with decision strategy based on Markov optimization. In multicell network, JReSBA with Interference Mitigation (JReSBA_IM) and Optimized JReSBA_IM (O_JReSBA_IM) are developed. JReSBA_IM deploys sectored-Fractional Frequency Reuse (sectored- FFR) partitioning concept in order to minimize the effect of ICI between adjacent cells. The performance is evaluated in terms of cell achievable rate, Outage Percentage (OP) and Satisfaction Index (SI). The result for single cell network shows that JReSBA_SR has notably improved the cell achievable rate by 35.0%, with reduced OP by 17.7% compared to non-joint scheme at the expense of slight increase in complexity at Relay Node (RN). O_JReSBA_SR has further improved the cell achievable rate by 13.9% while maintaining the outage performance with reduced complexity compared to JReSBA_SR due to the effect of optimization. The result for multicell network shows that JReSBA_IM enhances the cell achievable rate up to 65.1% and reduces OP by 35.0% as compared to benchmark scheme. Similarly, O_JReSBA_IM has significantly reduced the RN complexity of JReSBA_IM scheme, improved the cell achievable rate up to 9.3% and reduced OP by 1.3%. The proposed joint resource allocation has significantly enhanced the network performance through spatial frequency reuse, efficient, fair and optimized resource allocation. The proposed resource allocation is adaptable to variation of network load and can be used in any multihop cellular network such as Long Term Evolution-Advanced (LTE-A) network

Smart Agent and Modified Master-Backup Algorithm for Auto Switching Dynamic Host Configuration Protocol Relay through Wireless Router

Several problems happened in a wireless router which is the number of clients that connected to DHCP (Dynamic Host Configuration Protocol) services and also durability in connectivity. Wireless router which is used in the office nowadays usually has a small memory and also CPU power. Memory or CPU sometimes could be running out when a wireless router does some background services. DHCP is one of the services needed to run in a wireless router. DHCP is interrupted when memory or CPU is full. DHCP relay and modification of the backup algorithm needed to overcome this situation when the memory or CPU in the wireless router is limited. The modification of the backup algorithm is a mechanism to switch the main router with the backup router when the main router memory is busy. DHCP relay could become a DHCP server directly when the main router is busy. Wireless router in another side could be formatted with open-source OS such as OpenWRT to become bridge interface that connected to DHCP relay. The scenario that tested in this research is using Cisco DHCP relay services in combination with OpenWRT wireless router, in variation with Mikrotik original “capsman” protocol with DHCP relay in combination with wireless-enabled Mikrotik and also in combination with OpenWRT wireless router. The result shows that OpenWRT in configuration with DHCP relay and backup algorithm could extend the number of a client connected, and also the durability of the wireless router runs its services as DHCP forwarder to DHCP relay and DHCP server. Theoretically, the number of the client that could connect in class C IPv4 address is 253 clients. Practically, in some wireless router brand, the number of the client is limited to 15 to 30 clients because that number is an optimal client for consuming the bandwidth. DHCP relay scenario could extend that limit to have a larger number of the client, and the new backup algorithm in combination also doesn’t decrease IP release time significantly from usual DHCP using a direct connection

Conceção e desempenho de retransmissões sem fios cooperativas

Doutoramento em Engenharia Eletrotécnica/TelecomunicaçõesIn recent years, a new paradigm for communication called cooperative communications has been proposed for which initial information theoretic studies have shown the potential for improvements in capacity over traditional multi-hop wireless networks. Extensive research has been done to mitigate the impact of fading in wireless networks, being mostly focused on Multiple-Input Multiple-Output (MIMO) systems. Recently, cooperative relaying techniques have been investigated to increase the performance of wireless systems by using diversity created by different single antenna devices, aiming to reach the same level of performance of MIMO systems with low cost devices. Cooperative communication is a promising method to achieve high spectrum efficiency and improve transmission capacity for wireless networks. Cooperative communications is the general idea of pooling the resources of distributed nodes to improve the overall performance of a wireless network. In cooperative networks the nodes cooperate to help each other. A cooperative node offering help is acting like a middle man or proxy and can convey messages from source to destination. Cooperative communication involves exploiting the broadcast nature of the wireless medium to form virtual antenna arrays out of independent singleantenna network nodes for transmission. This research aims at contributing to the field of cooperative wireless networks. The focus of this research is on the relay-based Medium Access Control (MAC) protocol. Specifically, I provide a framework for cooperative relaying called RelaySpot which comprises on opportunistic relay selection, cooperative relay scheduling and relay switching. RelaySpot-based solutions are expected to minimize signaling exchange, remove estimation of channel conditions, and improve the utilization of spatial diversity, minimizing outage and increasing reliability.Nos últimos anos foi proposto um novo paradigma de comunicação, chamado de comunicação cooperativa, para o qual estudos iniciais de teoria da informação demonstraram ter potencial para melhorias na capacidade em redes sem fios tradicionais multi-hop. Uma extensa pesquisa tem sido realizada para mitigar o impacto da atenuação em redes sem fios, tendo-se debruçado principalmente em sistemas Multiple-Input Multiple-Output (MIMO). Recentemente têm sido investigadas técnicas de retransmissão cooperativas para aumentar o desempenho de sistemas sem fios, usando a diversidade criada por diferentes antenas individuais com o objetivo de atingir o mesmo nível de desempenho dos sistemas MIMO com dispositivos de baixo custo. A comunicação cooperativa é um método promissor para atingir uma elevada eficiência na ocupação espectral e melhorar a capacidade de transmissão em redes sem fios. A comunicação cooperativa tem por ideia base a junção de recursos de nós distribuídos para melhorar o desempenho global de uma rede sem fios. Em redes cooperativas os nós cooperam para ajudarem-se mutuamente. Um nó cooperativo que ofereça ajuda estará agindo como um intermediário ou mediador, podendo transmitir mensagens da origem para o destino. A comunicação cooperativa explora a natureza da transmissão em difusão das comunicações sem fios para formar antenas múltiplas virtuais com vários nós de rede independentes e com antenas únicas. Esta investigação visou contribuir para a área científica das redes sem fios cooperativas. O foco da pesquisa foi nos protocolos de controlo de acesso ao meio (MAC) com retransmissão cooperativa. Especificamente, proponho uma arquitetura para enquadrar a retransmissão cooperativa, chamada RelaySpot (ponto de retransmissão), que explora a seleção oportunista de retransmissores, o escalonamento de retransmissores cooperativos e a comutação entre retransmissores. As comunicações baseadas na RelaySpot deverão ter uma troca de sinalização reduzida, não usam estimativas das condições do canal e melhoram o aproveitamento da diversidade espacial, minimizando a interrupção e aumentando a fiabilidade

Improving Multicast Communications Over Wireless Mesh Networks

In wireless mesh networks (WMNs) the traditional approach to shortest path tree based multicasting is to cater for the needs of the poorest performingnode i.e. the maximum permitted multicast line rate is limited to the lowest line rate used by the individual Child nodes on a branch. In general, this meansfixing the line rate to its minimum value and fixing the transmit power to its maximum permitted value. This simplistic approach of applying a single multicast rate for all nodes in the multicast group results in a sub-optimal trade-off between the mean network throughput and coverage area that does not allow for high bandwidth multimedia applications to be supported. By relaxing this constraint and allowing multiple line rates to be used, the mean network throughput can be improved. This thesis presents two methods that aim to increase the mean network throughput through the use of multiple line rates by the forwarding nodes. This is achieved by identifying the Child nodes responsible for reducing the multicast group rate. The first method identifies specific locations for the placement of relay nodes which allows for higher multicast branch line rates to be used. The second method uses a power control algorithm to tune the transmit power to allow for higher multicast branch line rates. The use of power control also helps to reduce the interference caused to neighbouring nodes.Through extensive computer simulation it can be shown that these two methods can lead to a four-fold gain in the mean network throughput undertypical WMN operating conditions compared with the single line rate case

Unaprjeđenje cjelovitosti vojno-obrambenih komunikacijskih sustava s pomoću mrežnih pristupnih točaka s naglaskom na zemaljskim radiorelejnim vezama

Obvious changes in a very broad field of the information and communication technologies are the key driver of the accelerated development of every sphere of human activity, including private life. In the military organization, this technological progress is present through the “post 2000” concept of the networked implementation of operations, which is implemented to varying degrees in armies around the world. New confrontations on the modern front include demands for an ever-increasing volume of the electronic traffic, complexity of the systems that generate, share and consume information content, and above all, the fastest possible availability of the relevant information. The race for information superiority is accompanied, on the other hand, by an ever more destructive highly sophisticated threats, from classic degradations and physical destruction, action of the hybrid (intelligence-combat) platforms of the unmanned systems, to cyber-electromagnetic activities of an offensivedefensive nature. The new paradigms of the multi-domain warfare and expected scenarios that such forms of engagement put forward, demand from the modern military organization further normative arrangements within the functional area related to communication information systems. At the operational-strategic level, they imply the introduction of adequate organizational concepts and doctrines, while in the implementation part they require correction of the established tactics, techniques and procedures. In such an operational environment, integrative efforts within today’s militarydefence communication systems transformed into unique complete solutions have brought a special challenge. Key networking of the mission components is provided by network access points. For this reason, they are the subject of special attention of the network designers, both conceptually and in terms of implementation. The effectiveness of their functioning is also an assessment of the maturity of military thinking, inventiveness and engineering practice – which will bring along defeats or victories to any combat system in future challenges.Očigledne promjene na vrlo širokom području informacijsko-komunikacijskih tehnologija ključni su pokretač ubrzanog razvoja svake sfere ljudskog djelovanja – uključujući i privatni život. U vojnoj organizaciji ovaj tehnološki napredak prisutan je kroz tzv. post 2000 koncept umrežene provedbe operacija – koji se u različitim stupnjevima implementira u vojskama širom svijeta. Nova sučeljavanja na suvremenoj bojišnici uključuju zahtjeve za sve većim volumenom elektroničkih prometnica, usložnjavanja sustava koji generiraju, dijele i konzumiraju informacijske sadržaje te prije svega što bržu dostupnost relevantnih informacija. Utrku za informacijskom superiornošću s druge strane prate nikad destruktivnije visokosofisticirane prijetnje – od klasičnih degradacija i fizičkih uništenja, djelovanja hibridnih (obavještajno-borbenih) platformi besposadnih sustava, do kiberelektromagnetskih aktivnosti napadajno-obrambene prirode. Nove paradigme višedomenskog ratovanja i očekujući scenariji koje takvi oblici angažmana donose, od suvremene vojne organizacije traže daljnja normativna uređenja unutar funkcionalnog područja vezanog uz komunikacijsko-informacijske sustave. Ona na operativno-strategijskoj razini podrazumijevaju uvođenje adekvatnih organizacijskih koncepata i doktrina, dok u provedbenom dijelu traže korigiranje ustaljenih taktika, tehnika i procedura. U takvom operativnom okružju, poseban izazov donose integrativni napori unutar vojno-obrambenih komunikacijskih sustava današnjice, pretočeni u jedinstvena cjelovita rješenja. Ključnu umreženost misijskih sastavnica osiguravaju mrežne pristupne točke. Zbog tog su razloga predmetom od posebne pozornosti mrežnih dizajnera, i u konceptualnom i u izvedbenom smislu. Učinkovitost njihova funkcioniranja, ujedno je i ocjena zrelosti vojnog promišljanja, inventivnosti i inženjerske prakse – koja će u budućim izazovima svakom borbenom sustavu donositi poraze ili pobjede

Routing Strategies for Capacity Enhancement in Multi-hop Wireless Ad Hoc Networks

This thesis examines a Distributed Interference Impact Probing (DIIP) strategy for Wireless Ad hoc Networks (WANETs), using a novel cross-layer Minimum Impact Routing (MIR) protocol. Perfonnance is judged in tenns of interference reduction ratio, efficiency, and system and user capacity, which are calculated based on the measurement of Disturbed Nodes (DN). A large number of routing algorithms have been proposed with distinctive features aimed to overcome WANET's fundamental challenges, such as routing over a dynamic topology, scheduling broadcast signals using dynamic Media Access Control (MAC), and constraints on network scalability. However, the scalability problem ofWANET cannot simply adapt the frequency reuse mechanism designed for traditional stationary cellular networks due to the relay burden, and there is no single comprehensive algorithm proposed for it. DIIP enhances system and user capacity using a cross layer routing algorithm, MIR, using feedback from DIIP to balance transmit power in order to control hop length, which consequently changes the number of relays along the path. This maximizes the number of simultaneous transmitting nodes, and minimizes the interference impact, i.e. measured in tenns of 'disturbed nodes'. The perfonnance of MIR is examined compared with simple shortest-path routing. A WANET simulation model is configured to simulate both routing algorithms under multiple scenarios. The analysis has shown that once the transmitting range of a node changes, the total number of disturbed nodes along a path changes accordingly, hence the system and user capacity varies with interference impact variation. By carefully selecting a suitable link length, the neighbouring node density can be adjusted to reduce the total number of DN, and thereby allowing a higher spatial reuse ratio. In this case the system capacity can increase significantly as the number of nodes increases. In contrast, if the link length is chosen regardless ofthe negative impact of interference, capacity decreases. In addition, MIR diverts traffic from congested areas, such as the central part of a network or bottleneck points

Formulations and identification of algorithmic solutions for enabling opportunistic networks - M4.1

Milestone M4.1 del projecte Europeu OneFIT (ICT-2009-257385).This document contains a detailed description of the algorithms to be implemented to manage the opportunistic networks. There are defined according to the functional and system architecture (WP2) to fulfil the technical challenges. These algorithms will implemented during the WP4.2 and validated during the WP4.3Postprint (published version