Les réseaux sans fil multisauts présentent un certain nombre d'intérêts car ils n'ont pas besoin d'infrastructure fixe, sont peu coûteux et sont simples d'utilisation. Le mode DCF de IEEE 802.11 est souvent utilisé comme le protocole d'accès au canal pour les nœuds dans ces réseaux. Un avantage de ce protocole est qu'il est facile à implémenter. Pourtant, ses performances dépendent de deux facteurs importants : le partage du canal sans fil et les collisions entre paquets provenant des nœuds cachés. L'évaluation de ces paramètres est donc importante afin d'améliorer la performance de ce protocole. La première partie de la thèse est consacrée à l'évaluation de la bande passante disponible. C'est un paramètre qui est souvent utilisé pour le contrôle d'admission ou pour le routage dans ces réseaux. Dans la littérature, il existe de nombreuses méthodes qui permettent d'estimer la bande passante disponible sur un lien sans fil. Pourtant, ces méthodes ne prennent pas en compte la notion de retransmission qui est définie dans IEEE 802.11 et qui a clairement des impacts sur la bande passante disponible. Nous proposons donc une nouvelle méthode passive, appelée RABE (Retransmission-based Available Bandwidth Estimation). Notre méthode se base principalement sur des informations locales qui peuvent être détectées par chaque nœud du lien. Nous évaluons également la probabilité de collisions non conditionnelle des paquets provenant des nœuds cachés via un modèle analytique. Cette probabilité nous permet d'estimer le nombre moyen de retransmissions qui est ensuite utilisé pour évaluer d'autres paramètres utilisé par RABE. Les simulations réalisées avec le simulateur ns2.33 montrent que notre méthode produit des résultats plus précis que d'autres méthodes existantes / The first part of the thesis is devoted to the evaluation of the available bandwidth. This is a parameter that is often used for admission control in these networks. In the literature, there are many methods for estimating the available bandwidth on a wireless link. However, these methods do not take into account the concept of retransmission which is defined in IEEE 802.11 and have clear impacts on the available bandwidth. We propose therefore a new passive method called RABE (Retransmission-based Available Bandwidth Estimation). Our method is based mainly on local information that can be detected by each node. We also evaluate the unconditional collision probability of packets from hidden nodes via an analytical model. This probability allows us to estimate the average number of retransmissions, which is then used to evaluate other parameters used by RABE. The simulations performed with the simulator ns2.33 show that our method produces more accurate results than other existing solutions. In the second part, we focus on the distribution of idle periods of a node that is often used to evaluate the performance of wireless networks based on IEEE 802.11. The problem is that there are different assumptions for this distribution in literature. We first characterize different types of idle periods in some fundamental scenarios such as the scenario as asymetric hidden stations and the scenario of flow in the middle. We then generalize these types of idle periods for relatively highly loaded networks. The obtained simulation results in ns2.33 are similar to our proposed model. This work also brings out that these distributions are multimodal, unlike what is often assumed in the literature

Providing access to telecommunication services in rural areas is of paramount importance for the development of any country. Since the cost is the main inhibiting factor, any technical solution for access in sparsely populated rural areas has to be reliable, efficient, and deployable at low-cost. This thesis studies the utilization of Multihop Wireless Networks (MWN) as an appealing alternative for rural communication. MWN are designed with a self-configuring capability and can adapt to the addition or removal of network radio units (nodes). This makes them simple to install, allowing unskilled users to set up the network quickly. To increase the performance and cost-efficiency, this thesis focuses on the use of Advanced Antenna Systems (AAS) in rural access networks. AAS promise to increase the overall capacity in MWN, improving the link quality while suppressing or reducing the multiple access interference. To effectively exploit the capabilities of AAS, a proper design of Medium Access Control (MAC) protocols is needed. Hence, the results of system level studies into MAC protocols and AAS are presented in this thesis. Two different MAC protocols are examined: Spatial Time Division Multiple Access (STDMA) and Carrier Sense Multiple Access Collision Avoidance (CSMA/CA) with handshaking. The effects of utilizing advanced antennas on the end-to-end network throughput and packet delay are analyzed with routing, power control and adaptive transmission data rate control separately and in combination. Many of the STDMA-related research questions addressed in this thesis are posed as nonlinear optimization problems that are solved by the technique called "column generation" to create the transmission schedule using AAS. However, as finding the optimal solution is computationally expensive, we also introduce low-complexity algorithms that, while simpler, yield reasonable results close to the optimal solution. Although STDMA has been found to be very efficient and fair, one potential drawback is that it may adapt slower than a distributed approach like CSMA/CA to network changes produced e.g. by traffic variations and time-variant channel conditions. In CSMA/CA, nodes make their own decisions based on partial network information and the handshaking procedure allows the use of AAS at the transmitter and the receiver. How to effectively use AAS in CSMA/CA with handshaking is addressed in this thesis. Different beam selection policies using switched beam antenna systems are investigated. Finally, we demonstrate how the proposed techniques can be applied in a rural access scenario in Nicaragua. The result of a user-deployed MWN for Internet access shows that the supported aggregated end-to-end rate is higher than an Asymmetric Digital Subscriber Line (ADSL) connection. / QC 20100908

The aim of this work is to understand the requirements behind Quality of Service (QoS) for Multihop Wireless Networks and evaluate the performance of different such strategies. This work starts by establishing the basis for requirement of QoS and evaluates different approaches for providing QoS. Bandwidth is selected as the most important resource amongst the resources identified for ensuring QoS. The problem is modeled as an optimization problem that tries to maximize the amount of bandwidth available in the system while providing bounds over the bandwidth available over a route. Other QoS parameters are bound by hard limits and are not involved in the optimization problem. The existence of spatial reuse rules has been established through simulations for a TCP based network. This establishes that the reuse rules are independent of the MAC and network layer protocols used. This idea is used in designing the simulations for strategies that use controlled spatial reuse and give known bounds for QoS. Simulations take the network and a set of connections to generate the best possible schedule that guarantees bandwidth to individual connections and maximizes the total number of slots used in the entire system. The total number of slots used is a measure of the bandwidth in use. The set of graphs and connections is generated by a random graph and connection generator and the data set is large enough to average the results. There are two different approaches used for scheduling the connections. The first approach uses graph coloring and provides a simpler implementation in terms of network deployments. Second approach uses on-demand slot allocation. The approaches are compared for their pros and cons. The first approach uses graph coloring to allocate fixed number of slots to each link. This makes an equivalent of a wired network with fixed bandwidth over each link. This network is simpler to operate and analyze at the cost of one time expense of graph coloring. The assumption here is that the network is static or has low mobility. The on demand approach is more flexible in terms of slot assignment and is adaptable to the changing traffic patterns. The cons are that connection establishment is more expensive in terms of bandwidth required and is more complicated and difficult to analyze. The advantages include low initial network establishment cost and accommodation of mobility.

Η έννοια της ψηφιακής αναμετάδοσης έχει μελετηθεί σαν ένα ϑεωρητικό πρόβλημα από την πλευρά της ϑεωρίας της πληροφορίας στις δεκαετίες του ’70 και ’80 όπου υπολογίστηκε η χωρητικότητα συστημάτων με ένα αναμεταδότη. Το σενάριο στο οποίο η επικοινωνία δύο τερματικών σταθμών πραγματοποείται με τη ϐοήθεια ενός τρίτου το οποίο αναλαμβάνει να αναμεταδόσει την πληροφορία, υλοποιήθηκε αρχικά στους δορυφόρους με ανακλαστική επανεκπομπή. Ενδιαφέρον, σύμφωνα με όσα γνωρίζουμε, προκαλεί το γεγονός ότι δεν υπήρχε έως πολύ πρόσφατα καμία εργασία σχετική με την ϑεωρία της αναμετάδοσης - πιο πιθανή αιτία η μη ύπαρξη σχετικών εφαρμογών. Με την ωριμότητα των ψηφιακών ασύρματων επικοινωνιών και λόγω των ϱαγδαία αυξανόμενων αναγκών για επικοινωνίες υψηλής απόδοσης, ϕαίνεται ότι έφτασε η ώρα για την ανάπτυξη ‘‘έξυπνης’’ αναμετάδοσης στο άμεσο μέλλον. Η παρούσα διδακτορική διατριβή (DD) έρχεται να συμβάλλει προς την κατεύθυνση αυ- τή και να δώσει στους μελετητές των ψηφιακών επικοινωνιών νέες τεχνικές και εργαλεία αναλύοντας και μελετώντας στο ϕυσικό επίπεδο τα ασύρματα τηλεπικοινωνιακά συστήματα (ή δίκτυα) πολλαπλών αλμάτων με μη-αναγεννητικούς αναμεταδότες δηλ. συστήματα στα οποία το σήμα εκπέμπεται από τον πηγαίο κόμβο και ϕθάνει στον κόμβο προορισμού διαμέσου ενός ή περισσοτέρων αναμεταδοτών. Με την τεχνική αυτή καταπολεμούμε τους δύο ϐασικούς παράγοντες υποβάθμισης του εκπεμπόμενου σήματος που είναι η μειωμένη μέση ισχύς λήψης λόγω απόστασης ή/και εμποδίων, και οι διακυμάνσεις του σήματος στη λήψη του, εξαιτίας του ϕαινομένου των διαλείψεων. Βασικός σκοπός της DD είναι η αξιολόγηση των επιδόσεων των συστημάτων πολλαπλών αλμάτων, που λειτουργούν σε περιβάλλον διαλείψεων Rayleigh ή Nakagami-m, με δείκτες επιδόσεων όπως ο μέσος λό- γος σήματος προς ϑόρυβο (ΛΣΘ), η πιθανότητα διακοπής της επικοινωνίας (ΠDΕ) και η μέση πιθανότητα σφάλματος bit (ΜΠΣΒ). Για να επιτευχθούν τα παραπάνω στα πολυαλ- ματικά συστήματα, απαιτείται η στατιστική μελέτη του απ’ άκρο-σε-άκρο ΛΣΘ στην έξο- δο του κόμβου προορισμού για την εξαγωγή σημαντικών στατιστικών συναρτήσεων όπως της συνάρτησης πυκνότητας πιθανότητας (ΣΠΠ), της συνάρτησης αθροιστικής πιθανότητας (ΣΑΠ), της ϱοπο-γεννήτριας συνάρτησης (ΡΓΣ) και των ϱοπών. Οι δείκτες επίδοσης παρουσιάζονται είτε σε κλειστές μαθηματικές μορφές οι οποίες εξάγουν άμεσα αποτελέ- σματα, είτε σε αναλυτικές μορφές για τις οποίες η χρήση της αριθμητικής ολοκλήρωσης είναι απαραίτητη μέσω γνωστών μαθηματικών λογισμικών όπως MATHEMATICA ή MAPLE. Παράλληλα, όπου απαιτείται, παρουσιάζονται αποτελέσματα προσομοίωσης Monte Carlo για την επαλήθευση των αριθμητικών αποτελεσμάτων. Λαμβάνοντας υπόψην όλα τα παραπάνω, ερευνάται ένα σύστημα N αλμάτων σε περι- ϐάλλον διαλείψεων Nakagami-m και παράγονται τόσο σημαντικά αποτελέσματα για την επίδοσή τους όσο και ένα καινοτόμο στατιστικό ϑεώρημα για τη ΡΓΣ τυχαίων μεταβλητών Γάμμα. Η επίδοση των συστημάτων αυτών αξιολογείται για μη-αναγεννητικούς αναμε- ταδότες και συγκεκριμένα, τόσο για αναμεταδότες μεταβλητού κέρδους (ΑΜΚ) δηλ. το κέρδος τους εξαρτάται από την εκτίμηση της κατάστασης του καναλιού (ή κέρδος κανα- λιού) στην είσοδό τους, όσο και για αναμεταδότες σταθερού κέρδους (ΑΣΚ). Επίσης στη DD προτείνεται ένα νέος τύπου μη-αναγεννητικού αναμεταδότη, ο αναμεταδότης συνδυα- σμένου κέρδους (ΑΣυΚ), του οποίου η επίδοση εξετάζεται σε ένα σύστημα διπλού άλματος (δηλ. σ’ ένα σύστημα με έναν αναμεταδότη). Η επίδοσή του συγκρίνεται με αυτή του ΑΜΚ. Η επίδοση του ΑΣυΚ εμφανίζεται να είναι καλύτερη σε κάποιες περιπτώσεις απ’ αυτήν του ΑΜΚ. Ιδιαίτερη ϐαρύτητα δίνεται τέλος και στη μελέτη πολυαλματικών συστημάτων επικοινω- νίας με διαφορική συνεργασία χρηστών. Τα συστήματα αυτά διαφέρουν από τα συμβατικά πολυαλματικά διότι εκμεταλλεύονται τα πλεονεκτήματα της ‘‘εικονικής’’ διαφορικής εκ- πομπής στον πηγαίο κόμβο και τη διαφορική λήψη στον κόμβο προορισμού. Οι δείκτες επίδοσης εξετάζονται είτε για συστήματα διαφορικής συνεργασίας ενός χρήστη, είτε για πολλούς χρήστες με διαφορικό δέκτη συνδυασμού επιλογής ή μεγίστου λόγου στον κόμβο προορισμού, αντίστοιχα. / The concept of digital relaying has been studied as a theoretical problem from a network information theory perspective in 70’s and 80’s, and capacity regions of simple relaying channels have been evaluated. The scenario where the communication between two terminal is achieved with the help of a third terminal, was firstly implemented in bentpipe satellites. To the best of our knowledge, there has been no other analytical study on this concept until very recently due to the fact that there were no foreseeable applications at that time. With the maturity of digital wireless technologies and with the overwhelming demand for high data rate coverage, it seems that time has finally arrived for the implementation of intelligent relaying. The present PhD thesis contributes in that direction and gives to researchers of digital communications new techniques and smart tools by analyzing and studying multihop wireless communications systems in physical layer. In multihop systems, the source terminal transmits a signal which arrives to the destination terminal via a number of relays. By applying relayed transmission we mitigate two main reasons that causes Quality of Service degradation of the received signal, which are the low average receive power, induced by the presence of obstacles or by long distance, or due to the fluctuations in the received signal induced by fading effects. The main subject of this PhD is the evaluation of the performance metrics of multihop wireless communications systems, operating over Rayleigh or Nakagamim fading channels such as average signaltonoise ratio (SNR), outage probability and average biterror rate. To achieve this, the statistics of the equivalent endtoend SNR at the output of the destination terminal is required and specifically the probability density function, the cumulative distribution function, the moments and moment generating function (MGF). The performance metrics are presented either in closed forms giving direct results or in analytical ones where the results are extracted via numerical integration with the use of standard mathematical software packages such as MATHEMATICA or MAPLE. Additionally, Monte Carlo simulation results are also presented for the verification of the numerical results. Considering all the above, a multihop system with Nhops over Nakagamim environment is studied, and important performance results are derived. Also, a novel statistical result regarding the MGF of the product of rational powers of Gamma random variables is presented for the first time in the technical literature. The performance metrics of the multihop system are evaluated for nonregenerative relays and specifically, for both channel state information (CSI)based and fixed gain relays. Moreover, in this PhD thesis a new type of relay is presented, the combined gain relay (CGR), and its performance is studied in dualhop systems. The performance of the CGRs is compared to CSIbased ones whose amplification gain depends on the channel state at their input. It is interesting that CGR performs better in some situations than CSI ones. Finally, we concentrate on multihop wireless communications systems with cooperative diversity. Cooperative diversity systems differ from conventional multihop ones since exploits the benefits of virtual transmit diversity in the source terminal and diversity reception in the destination terminal. Performance analysis is conducted for cooperative diversity systems with one or more users (relays) and selection combiner or maximal ratio combiner at the destination terminal, correspondingly.

In the last few years, the number of real-time applications has increased. These applications are sensitive and require the methods to utilize existing network capacity efficiently to meet performance requirements and achieve the maximum throughput to overcome delay, jitter and packet loss. In such cases, when the network needs to support highly interactive traffic like packet-switched voice, the network congestion is an issue that can lead to various problems. If the level of congestion is high enough, the users may not be able to complete their calls and have existing calls dropped or may experience a variety of delays that make it difficult to participate smooth conversation. In this paper, we investigate the effect of priority levels on soft real-time performance. We use the priority queues to help us manage the congestion, handle the interactive traffic and improve the over all performance of the system. We consider switched multi-hop network with priority queues. All the switches and end-nodes control the real-time traffic with “Earlier Deadline First” scheduling. The performance of the network is characterized in terms of the average delay, the deadline missing ratio and the throughput. We will analyze these parameters with both the bursty traffic and evenly distributed traffic. We will analyze different priority levels and will see how the increase in priority level increases the performance of the soft real-time system.

Environmental monitoring represents a major application domain for wireless sensor networks (WSN). However, despite significant advances in recent years, there are still many challenging issues to be addressed to exploit the full potential of the emerging WSN technology. In this dissertation, we introduce the design and implementation of low-power wireless sensor networks for long-term, autonomous, and near-real-time environmental monitoring applications. We have developed an out-of-box solution consisting of a suite of software, protocols and algorithms to provide reliable data collection with extremely low power consumption. Two wireless sensor networks based on the proposed solution have been deployed in remote field stations to monitor soil moisture along with other environmental parameters. As parts of the ever-growing environmental monitoring cyberinfrastructure, these networks have been integrated into the Texas Environmental Observatory system for long-term operation. Environmental measurement and network performance results are presented to demonstrate the capability, reliability and energy-efficiency of the network.

No description available.

We consider the transmission of correlated sources over a multiple access channel(MAC). Multiple access channels are important building blocks in many practical communication systems, e.g., local area networks(LAN), cellular systems, wireless multi-hop networks. Thus this topic has been studied for last several decades. One recent motivation is estimating a random field via wireless sensor networks. Often the sensor nodes are densely deployed resulting in correlated observations. These sensor nodes need to transmit their correlated observations to a fusion center which uses this data to estimate the sensed random field. Sensor nodes have limited computational and storage capabilities and very limited energy. Since transmission is very energy intensive, it is important to minimize it. This motivates our problem of energy efficient transmission of correlated sources over a sensor network. Sensor networks are often arranged in a hierarchical fashion. Neighboring nodes can first transmit their data to a cluster head which can further compress information before transmission to the fusion center. The transmission of data from sensor nodes to their cluster-head is usually through a MAC. At the fusion center the underlying physical process is estimated. The main trade-off possible is between the rates at which the sensors send their observations and the distortion incurred in estimation at the fusion center. The availability of side information at the encoders and/or the decoder can reduce the rate of transmission. In this thesis, the above scenario is modeled as an information theoretic problem. Efficient joint source-channel codes are discussed under various assumptions on side information and distortion criteria. Sufficient conditions for transmission of discrete/continuous alphabet sources with a given distortion over a discrete/continuous alphabet MAC are given. We recover various previous results as special cases from our results. Furthermore, we study the practically important case of the Gaussian MAC(GMAC) in detail and propose new joint source-channel coding schemes for discrete and continuous sources. Optimal schemes are identified in different scenarios. The protocols like TDMA, FDMA and CDMA are widely used across systems and standards. When these protocols are used the MAC becomes a system of orthogonal channels. Our general conditions can be specialized to obtain sufficient conditions for lossy transmission over this system. Using this conditions, we identify an optimal scheme for transmission of Gaussian sources over orthogonal Gaussian channels and show that the Amplify and Forward(AF) scheme performs close to the optimal scheme even at high SNR. Next we investigate transmission of correlated sources over a fast fading MAC with perfect or partial channel state information available at both the encoders and the decoder. We provide sufficient conditions for transmission with given distortions. We also provide power allocation policies for efficient transmission. Next, we use MAC with side information as a building block of a hierarchical sensor network. For Gaussian sources over Gaussian MACs, we show that AF performs well in such sensor network scenarios where the battery power is at a premium. We then extend this result to the hierarchical network scenario and show that it can perform favourably to the Slepian-Wolf based source coding and independent channel coding scheme. In a hierarchical sensor network the cluster heads often need to send only a function of the sensor observations to the fusion center. In such a setup the sensor nodes can compress the data sent to the cluster head exploiting the correlation in the data and also the structure of the function to be computed at the cluster head. Depending upon the function, exploiting the structure of the function can substantially reduce the data rate for transmission. We provide efficient joint source-channel codes for transmitting a general class of functions of the sources over the MAC.

Orientador: Michel Daoud Yacoub / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-10T09:17:00Z (GMT). No. of bitstreams: 1 Medeiros_AlvaroAugustoMachadode_D.pdf: 910419 bytes, checksum: 8fee720ee964b6908659ff1ab27c754e (MD5) Previous issue date: 2007 / Resumo: As redes ad hoc são redes sem um controle centralizado, cujos nós se comunicam através de um canal sem fio diretamente ou através de múltiplos saltos. Uma questão complexa referente a redes ad hoc é o cálculo da capacidade. Estimar quantas transmissões a rede permite, garantindo qualidade de serviço aos usuarios é uma tarefa difícil em virtude de duas características da rede: o canal sem fio e as transmissões em múltiplos saltos. Este trabalho propõe um novo método para cálculo da capacidade através da probabilidade de outage que considera ambos os aspectos. Este método apresenta vantagens como fácil implantação, baixo esforço computacional e resultados praticamente indistinguíveis daqueles obtidos atraves de simulação. O metodo pode ser aplicado aos mais variados ambientes de propagação e qualquer topologia de rede. Modelos de interferência mais realistas, bem como a questão do roteamento são também abordados ao longo do trabalho / Abstract: Ad hoc networks are networks that operate without centralized control, whose nodes communicate through wireless links in a single or multihop way. A complex issue about ad hoc networks is the capacity estimation. The computation of how many transmissions the network can support ensuring a quality of service for its users is a difficult task due to two central aspects: the wireless medium and the multihop nature of transmissions. An analytical method to calculate the capacity through the computation of the outage probability considering both aspects is proposed in this work. This method presents advantages such as simple implementation, low computational efforts and practically indistinguishable results from those obtained through simulation. This method can be applied to many propagation environments and to any network topology. More realistic interference models and the routing issue are also described along this work / Doutorado / Telecomunicações e Telemática / Doutor em Engenharia Elétrica

Abstract The high increase in traffic and data rate for future generations of mobile communication systems, with simultaneous requirement for reduced power consumption, makes Multihop Cellular Networks (MCNs) an attractive technology. To exploit the potentials of MCNs a number of new network paradigms are proposed in this thesis. First, a new algorithm for efficient relaying topology control is presented to jointly optimize the relaying topology, routing and scheduling resulting in a two dimensional or space time routing protocol. The algorithm is aware of intercell interference (ICI), and requires coordinated action between the cells to jointly choose the relaying topology and scheduling to minimize the system performance degradation due to ICI. This framework is extended to include the optimization of power control. Both conventional and cooperative relaying schemes are considered. In addition, a novel sequential genetic algorithm (SGA) is proposed as a heuristic approximation to reconfigure the optimum relaying topology as the network traffic changes. Network coding is used to combine the uplink and downlink transmissions, and incorporate it into the optimum bidirectional relaying with ICI awareness. Seeking for a more tractable network model to effectively use context awareness and relying on the latest results on network information theory, we apply a hexagonal tessellation for inner partition of the cell into smaller subcells of radius r. By using only one single topology control parameter (r), we jointly optimize routing, scheduling and power control to obtain the optimum trade-off between throughput, delay and power consumption in multicast MCNs. This model enables high resolution optimization and motivates the further study of network protocols for MCNs. A new concept for route discovery protocols is developed and the trade-off between cooperative diversity and spatial reuse is analyzed by using this model. Finally, a new architecture for MCN is considered where multihop transmissions are performed by a Delay Tolerant Network, and new solutions to enhance the performance of multicast applications for multimedia content delivery are presented. Numerical results have shown that the algorithms suggested in this thesis provide significant improvement with respect to the existing results, and are expected to have significant impact in the analysis and design of future cellular networks. / Tiivistelmä Tiedonsiirron ja tiedonsiirtonopeuksien suuri kasvu sekä tehonkulutuksen pieneneminen tulevien sukupolvien matkapuhelinjärjestelmissä tekevät monihyppyiset matkapuhelinverkot houkutteleviksi vaihtoehdoiksi. Tässä työssä esitetään uusia tiedonsiirtoverkkojen paradigmoja monihyppyisten matkapuhelinverkkojen hyödyntämiseksi. Työssä esitellään uusi algoritmi tehokkaaseen releointitopologian hallintaan, joka optimoi yhtäaikaisesti topologian, reitityksen sekä lähetyshetkien ajoituksen ja mahdollistaa tila-aika-reititysprotokollan toteutuksen. Esitetty algoritmi huomioi solujen keskinäishäiriön ja vaaditulla solujen välisellä koordinoidulla hallinnalla saadaan yhdessä valittua topologia ja ajoitus, jotka minimoivat solujen keskinäisistä häiriöistä johtuvan suorituskyvyn heikentymisen. Myöhemmin tätä viitekehystä on laajennettu lisäämällä siihen tehonsäädön optimointi. Työssä on tutkittu sekä perinteisiä että kooperatiivisia releointimenetelmiä. Lisäksi työssä esitetään uusi geneettinen algoritmi heuristiseksi approksimaatioksi verkon liikenteen muutoksen vaatimaan releointitopologian uudelleen järjestelyyn. Työssä tarkastellaan lisäksi verkkokoodausta ylä- ja alasuuntaan tapahtuvan tiedonsiirron yhdistämiseksi sisällyttämällä se solujen keskinäishäiriön huomioivaan kahdensuuntaiseen releointiin. Etsittäessä paremmin mukautuvaa ja kontekstitietoisuutta hyödyntävää verkkomallia, joka käyttää hyväkseen viimeisimpiä verkkojen informaatioteoreettisia tuloksia, voidaan verkon solut pilkkoa pienempiin kuusikulmaisiin alisoluihin. Käyttämällä ainoastaan näiden alisolujen sädettä r voidaan puolestaan verkon reititys, ajoitus ja tehon säätö optimoida yhtäaikaisesti saavuttaen paras mahdollinen kompromissi verkon läpäisyn, viiveen ja tehonkulutuksen välillä. Kehitetty malli mahdollistaa korkean resoluution optimoinnin ja motivoi uusien verkkoprotokollien kehitystä monihyppyisissä matkapuhelinverkoissa. Tätä mallia käyttäen esitellään myös uusi konsepti reitinetsintäprotokollille sekä analysoidaan kooperatiivisen diversiteetin ja tila-avaruudessa tapahtuvan uudelleenkäytön välistä kompromissiratkaisua. Lopuksi työssä tarkastellaan monihyppyisen matkapuhelinverkon uutta arkkitehtuuria, jossa monihyppylähetykset suoritetaan viivesietoisella verkolla ja esitetään uusia ratkaisuja multimediasisällön monilähetysten tehokkuuden parantamiseksi. Työssä saadut tulokset osoittavat, että ehdotetut algoritmit parantavat järjestelmien suorituskykyä verrattuna aiemmin tiedossa olleisiin tuloksiin. Työn tuloksilla voidaan olettaa myös olevan suuri vaikutus tulevaisuuden matkapuhelinverkkojen analysointiin ja suunnitteluun.