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Multilayer optimization in radio resource allocation for the packet transmission in wireless networks

Nascimento, Alberto Jesus de
Fonte: Universidade da Madeira Publicador: Universidade da Madeira
Tipo: Tese de Doutorado
Publicado em //2009 Português
Relevância na Pesquisa
89.20804%
In the last decade mobile wireless communications have witnessed an explosive growth in the user’s penetration rate and their widespread deployment around the globe. It is expected that this tendency will continue to increase with the convergence of fixed Internet wired networks with mobile ones and with the evolution to the full IP architecture paradigm. Therefore mobile wireless communications will be of paramount importance on the development of the information society of the near future. In particular a research topic of particular relevance in telecommunications nowadays is related to the design and implementation of mobile communication systems of 4th generation. 4G networks will be characterized by the support of multiple radio access technologies in a core network fully compliant with the Internet Protocol (all IP paradigm). Such networks will sustain the stringent quality of service (QoS) requirements and the expected high data rates from the type of multimedia applications to be available in the near future. The approach followed in the design and implementation of the mobile wireless networks of current generation (2G and 3G) has been the stratification of the architecture into a communication protocol model composed by a set of layers...

Quality-of-Service provision for satellite systems implementing adaptive physical layer

Fausto Vieira
Fonte: Universidade do Porto Publicador: Universidade do Porto
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
49.189106%
Wireless communications have always been characterised by the challenge of fully exploiting the channel capacity limits. In the past, it was usually necessary to reach a compromise between spectral efficiency and service availability. New developments in wireless technology provide a breakthrough performance since complexity is introduced as a new degree of freedom in the classical spectral efficiency versus service availability compromise.New wireless communication systems provide Fade Mitigation Techniques (FMT) that allow for the transmission to constantly adapt itself to the channel conditions. DVB-S2 is the standard for second-generation specification for satellite broadcasting and it makes normative the use of Adaptive Coding and Modulation (ACM) as a FMT for interactive applications, hence implementing an Adaptive Physical Layer. The channel conditions must be reported by interactive terminals in order to implement the adaptability to the channel conditions.The introduction of an Adaptive Physical Layer creates an impact in the entire system design due to the fact that capacity is no longer constant, but rather time-and-location dependent. The basic assumption of having a constant capacity was a fundamental postulation in the classical communications systems design...

Joint design of RFID reader and tag anti-collision algorithms: a cross-layer approach

Gameiro, Atílio; Samano, Ramiro
Fonte: IARIA Publicador: IARIA
Tipo: Conferência ou Objeto de Conferência
Português
Relevância na Pesquisa
88.69097%
This paper investigates the potential interactions between reader and tag anti-collision algorithms of passive RFID (radio frequency identification) systems. Conventionally, reader and tag anti-collision algorithms are designed by assuming that they are independent from each other. In practice, however, readers and tags usually operate in the same frequency band. Therefore, contention between their transmissions can also potentially arise. Furthermore, reader anti-collision policies directly influence the way in which tags are activated, and thus also the way in which they collide when responding to reader’s requests. In view of this and considering the growing numbers of readers and tags, independence of both schemes can not longer be considered as a realistic assumption. This paper partially fills this gap by proposing a new cross-layer framework for the joint evaluation and optimization of reader and tag anticollision algorithms. Furthermore, the paper proposes a new approach, based on a Markov model, which allows capacity and stability analysis of asymmetrical RFID systems (i.e., when readers and tags experience different channel and queuing states). The model captures the dynamics of tag activation and tag detection processes of RFID. It also represents a first step towards a joint design of physical (PHY) and medium access control layers (MAC) of RFID. The results indicate that the proposed approach provides benefits in terms of stability and capacity over conventional solutions even when readers and tags operate in different channels. The results also provide useful guidelines towards the cross-layer design of future RFID platforms.

Cross-Layer Adaptive Feedback Scheduling of Wireless Control Systems

Xia, Feng; Ma, Longhua; Peng, Chen; Sun, Youxian; Dong, Jinxiang
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 15/07/2008 Português
Relevância na Pesquisa
58.679604%
There is a trend towards using wireless technologies in networked control systems. However, the adverse properties of the radio channels make it difficult to design and implement control systems in wireless environments. To attack the uncertainty in available communication resources in wireless control systems closed over WLAN, a cross-layer adaptive feedback scheduling (CLAFS) scheme is developed, which takes advantage of the co-design of control and wireless communications. By exploiting cross-layer design, CLAFS adjusts the sampling periods of control systems at the application layer based on information about deadline miss ratio and transmission rate from the physical layer. Within the framework of feedback scheduling, the control performance is maximized through controlling the deadline miss ratio. Key design parameters of the feedback scheduler are adapted to dynamic changes in the channel condition. An event-driven invocation mechanism for the feedback scheduler is also developed. Simulation results show that the proposed approach is efficient in dealing with channel capacity variations and noise interference, thus providing an enabling technology for control over WLAN.

Ambient Intelligence Context-Based Cross-Layer Design in Wireless Sensor Networks

Liu, Yang; Seet, Boon-Chong; Al-Anbuky, Adnan
Fonte: MDPI Publicador: MDPI
Tipo: Artigo de Revista Científica
Publicado em 14/10/2014 Português
Relevância na Pesquisa
58.406816%
By exchanging information directly between non-adjacent protocol layers, cross-layer (CL) interaction can significantly improve and optimize network performances such as energy efficiency and delay. This is particularly important for wireless sensor networks (WSNs) where sensor devices are energy-constrained and deployed for real-time monitoring applications. Existing CL schemes mainly exploit information exchange between physical, medium access control (MAC), and routing layers, with only a handful involving application layer. For the first time, we proposed a framework for CL optimization based on user context of ambient intelligence (AmI) application and an ontology-based context modeling and reasoning mechanism. We applied the proposed framework to jointly optimize MAC and network (NET) layer protocols for WSNs. Extensive evaluations show that the resulting optimization through context awareness and CL interaction for both MAC and NET layer protocols can yield substantial improvements in terms of throughput, packet delivery, delay, and energy performances.

Cross-layer design and optimization for wireless sensor networks

Lim, Tat Lee
Fonte: Monterey California. Naval Postgraduate School Publicador: Monterey California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
69.097227%
Cross-layer design and optimization is a new technique which can be used to design and improve the performance in both wireless and wireline networks. The central idea of cross-layer design is to optimize the control and exchange of information over two or more layers to achieve significant performance improvements by exploiting the interactions between various protocol layers. In this thesis, a cross-layer design and optimization framework was proposed and the concept of using the optimization agent to provide the exchange and control of information between the protocol layers was also introduced. The approach for this thesis is to investigate the effects of the wireless channel and the performance of a small scale wireless sensor network (WSN) to develop insights that can be used in the design and development of the optimization agent in the proposed cross-layer framework. A tap delay line (TDL) model was developed and simulated in MATLAB to investigate the effects of the wireless channel impairments due to mobility and multipath fading. Performance measurements were also conducted to study the effects of interference and transmission range for a group of networked wireless sensors.

Contribution to the cross-layer optimization of intra-cluster communication mechanisms in personal networks; Contribución a la optimización intercapa de los mecanismos de comunicación intra-cluster en redes personales

Sánchez González, Luis
Fonte: Universidad de Cantabria Publicador: Universidad de Cantabria
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
68.66075%
RESUMEN: En el futuro, los dispositivos digitales formarán parte del entorno en el que las personas se desenvuelvan, participarán en nuestros objetivos y necesidades y nos ayudarán a "hacer más haciendo menos". A través de los dispositivos portátiles o aquellos que estén embebidos a nuestro alrededor el usuario será capaz de interactuar con el futuro universo de servicios e infraestructuras ubicuas. El principal paradigma que se seguirá se basa en que este universo estará centrado en el usuario ya que éste demandará los servicios que más le convengan en cualquier momento y lugar, todo ello preservando nuestra privacidad y seguridad. Este nuevo concepto no sólo se aplica a un entorno de ocio sino que en el campo profesional las redes inalámbricas de próxima generación permitirán incrementar nuestra productividad, reduciendo el peso de tareas repetitivas, poniendo a nuestra disposición la información relevante en el momento adecuado y según sean las necesidades particulares del usuario en ese momento y permitiéndonos trabajar con otras personas independientemente de donde se encuentren. En particular, se intuye que las redes de próxima generación se diseñen de forma que aglutinen todos los servicios disponibles a través de los diferentes sistemas que existan de forma que las posibles deficiencias de alguno de ellos se vean compensadas por otro. Lo que se pretende conseguir es que el usuario pueda disfrutar en todo momento y lugar de los servicios que desee sin que ello suponga un esfuerzo. Este concepto implica diferentes retos tecnológicos y la integración de múltiples sistemas. Dentro de estos retos tecnológicos esta Tesis aborda los siguientes: soporte de la heterogeneidad en lo referente a las tecnologías de acceso radio que existen y que eventualmente aparecerán en el futuro y que coexistirán en un mismo terminal; desarrollo de técnicas de optimización basadas en la cooperación entre diferentes capas de la pila de protocolos; implementación de estrategias de selección de la red que mejor pueda soportar un determinado servicio ante la posibilidad de utilización de múltiples tecnologías de acceso; optimización del uso de recursos energéticos en las comunicaciones dentro de la red; protección de la privacidad y la seguridad de las comunicaciones personales del usuario. Desde el punto de vista de las aportaciones...

OPTIMIZATION OF RATELESS CODED SYSTEMS FOR WIRELESS MULTIMEDIA MULTICAST

CAO, YU
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
58.391387%
Rateless codes, also known as fountain codes, are a class of erasure error-control codes that are particularly well suited for broadcast/multicast systems. Raptor codes, as a particularly successful implementation of digital fountain codes, have been used as the application layer forward error correction (FEC) codes in the third generation partnership program (3GPP) Multimedia Broadcast and Multicast Services (MBMS) standard. However, the application of rateless codes to wireless multimedia broadcast/multicast communications has yet to overcome two major challenges: first, wireless multimedia communications usually has stringent delay requirements. In addition, multimedia multicast has to overcome heterogeneity. To meet these challenges, we propose a rateless code design that takes the layered nature of source traffic as well as the varying quality of transmission channels into account. A convex optimization framework for the application of unequal error protection (UEP) rateless codes to synchronous and asynchronous multimedia multicast to heterogeneous users is proposed. A second thread of the thesis addresses the noisy, bursty and time- varying nature of wireless communication channels that challenge the assumption of erasure channels often used for the wired internet. In order to meet this challenge...

Encaminamiento en redes inalámbricas malladas para minimizar la exposición de los usuarios a los campos electromagnéticos; Design and Implementation of an EMF-aware routing scheme for wireless mesh networks

Igareda Laso, Julián
Fonte: Universidade de Cantabria Publicador: Universidade de Cantabria
Tipo: Trabalho de Conclusão de Curso
Português
Relevância na Pesquisa
57.902495%
RESUMEN: Resulta incontestable que hoy en día las comunicaciones de carácter inalámbrico poseen un alto grado de aceptación, con una notable penetración entre los sistemas de telecomunicaciones, que van desde soluciones de telefonía móvil hasta redes de uso personal como Bluetooth, WIFI… Estas circunstancias han desembocado en una cierta preocupación sobre los posibles efectos adversos en la salud que puedan tener este tipo de redes, dado que, aunque utilizan radiación que no está considerada ionizante, crean una cierta exposición electromagnética sobre los usuarios. Esto se ha convertido en una cuestión que genera cierta controversia en la sociedad y es por ello por lo que nace el proyecto Low EMF Exposure Networks (LEXNET). En él, se trata de catalogar, desarrollar e implementar mecanismos para la reducción de la exposición electromagnética a la que se ve sometida el usuario, sin conllevar una reducción ni en la calidad de servicio (Quality of Service (QoS)), ni en la de experiencia (Quality of Experience (QoE)). Este trabajo n de grado se enmarca en este proyecto. Primeramente se planteará un estudio teórico, que permita abordar la problemática de este tipo de entornos, para posteriormente afrontar el diseño e implementación de un algoritmo basado en la teoría de grafos. Por último...

CoopGeo: A Beaconless Geographic Cross-Layer Protocol for Cooperative Wireless Ad Hoc Networks

Aguilar, Teck; Syue, Syue-Ju; Gauthier, Vincent; Afifi, Hossam; Wang, Chin-Liang
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 17/05/2012 Português
Relevância na Pesquisa
58.572314%
Cooperative relaying has been proposed as a promising transmission technique that effectively creates spatial diversity through the cooperation among spatially distributed nodes. However, to achieve efficient communications while gaining full benefits from cooperation, more interactions at higher protocol layers, particularly the MAC (Medium Access Control) and network layers, are vitally required. This is ignored in most existing articles that mainly focus on physical (PHY)-layer relaying techniques. In this paper, we propose a novel cross-layer framework involving two levels of joint design---a MAC-network cross-layer design for forwarder selection (or termed routing) and a MAC-PHY for relay selection---over symbol-wise varying channels. Based on location knowledge and contention processes, the proposed cross-layer protocol, CoopGeo, aims at providing an efficient, distributed approach to select next hops and optimal relays along a communication path. Simulation results demonstrate that CoopGeo not only operates properly with varying densities of nodes, but performs significantly better than the existing protocol BOSS in terms of packet error rate, transmission error probability, and saturated throughput.

Cross-layer design of distributed sensing-estimation with quality feedback, Part I: Optimal schemes

Michelusi, Nicolo; Mitra, Urbashi
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
58.30649%
This two-part paper presents a feedback-based cross-layer framework for distributed sensing and estimation of a dynamic process by a wireless sensor network (WSN). Sensor nodes wirelessly communicate measurements to the fusion center (FC). Cross-layer factors such as packet collisions and the sensing-transmission costs are considered. Each SN adapts its sensing-transmission action based on its own local observation quality and the estimation quality feedback from the FC under cost constraints for each SN. In this first part, the optimization complexity is reduced by exploiting the statistical symmetry and large network approximation of the WSN. Structural properties of the optimal policy are derived for a coordinated and a decentralized scheme. It is proved that a dense WSN provides sensing diversity, so that only a few SNs with the best local observation quality need to be activated, despite the fluctuations of the WSN. The optimal policy dictates that, when the estimation quality is poor, only the best SNs activate, otherwise all SNs remain idle to preserve energy. The costs of coordination and feedback are evaluated, revealing the scalability of the decentralized scheme to large WSNs, at the cost of performance degradation. Simulation results demonstrate cost savings from 30% to 70% over a non-adaptive scheme...

Cross-layer design of distributed sensing-estimation with quality feedback, Part II: Myopic schemes

Michelusi, Nicolo; Mitra, Urbashi
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
58.15259%
This two-part paper presents a feedback-based cross-layer framework for distributed sensing and estimation of a dynamic process by a wireless sensor network (WSN). Sensor nodes wirelessly communicate measurements to the fusion center (FC). Cross-layer factors such as packet collisions and the sensing-transmission costs are considered. Each SN adapts its sensing-transmission action based on its own local observation quality and the estimation quality feedback from the FC under cost constraints for each SN. In this second part, low-complexity myopic sensing-transmission policies (MPs) are designed to optimize a trade-off between performance and the cost incurred by each SN. The MP is computed in closed form for a coordinated scheme, whereas an iterative algorithm is presented for a decentralized one, which converges to a local optimum. The MP dictates that, when the estimation quality is poor, only the best SNs activate, otherwise all SNs remain idle to preserve energy. For both schemes, the threshold on the estimation quality below which the SNs remain idle is derived in closed form, and is shown to be independent of the number of channels. It is also proved that a single channel suffices for severely energy constrained WSNs. The proposed MPs are shown to yield near-optimal performance with respect to the optimal policy of Part I...

Delay-Aware Cross-Layer Design for Network Utility Maximization in Multi-hop Networks

Xiong, Haozhi; Li, Ruogu; Eryilmaz, Atilla; Ekici, Eylem
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 07/12/2010 Português
Relevância na Pesquisa
58.365293%
We investigate the problem of designing delay-aware joint flow control, routing, and scheduling algorithms in general multi-hop networks for maximizing network utilization. Since the end-to-end delay performance has a complex dependence on the high-order statistics of cross-layer algorithms, earlier optimization-based design methodologies that optimize the long term network utilization are not immediately well-suited for delay-aware design. This motivates us in this work to develop a novel design framework and alternative methods that take advantage of several unexploited design choices in the routing and the scheduling strategy spaces. In particular, we reveal and exploit a crucial characteristic of back pressure-type controllers that enables us to develop a novel link rate allocation strategy that not only optimizes long-term network utilization, but also yields loop free multi-path routes} between each source-destination pair. Moreover, we propose a regulated scheduling strategy, based on a token-based service discipline, for shaping the per-hop delay distribution to obtain highly desirable end-to-end delay performance. We establish that our joint flow control, routing, and scheduling algorithm achieves loop-free routes and optimal network utilization. Our extensive numerical studies support our theoretical results...

Decomposition Principles and Online Learning in Cross-Layer Optimization for Delay-Sensitive Applications

Fu, Fangwen; van der Schaar, Mihaela
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 05/12/2008 Português
Relevância na Pesquisa
58.811216%
In this paper, we propose a general cross-layer optimization framework in which we explicitly consider both the heterogeneous and dynamically changing characteristics of delay-sensitive applications and the underlying time-varying network conditions. We consider both the independently decodable data units (DUs, e.g. packets) and the interdependent DUs whose dependencies are captured by a directed acyclic graph (DAG). We first formulate the cross-layer design as a non-linear constrained optimization problem by assuming complete knowledge of the application characteristics and the underlying network conditions. The constrained cross-layer optimization is decomposed into several cross-layer optimization subproblems for each DU and two master problems. The proposed decomposition method determines the necessary message exchanges between layers for achieving the optimal cross-layer solution. However, the attributes (e.g. distortion impact, delay deadline etc) of future DUs as well as the network conditions are often unknown in the considered real-time applications. The impact of current cross-layer actions on the future DUs can be characterized by a state-value function in the Markov decision process (MDP) framework. Based on the dynamic programming solution to the MDP...

A Cross-Layer Design Based on Geographic Information for Cooperative Wireless Networks

Aguilar, Teck; Ghedira, Mohamed Chedly; Syue, Syue-Ju; Gauthier, Vincent; Afifi, Hossam; Wang, Chin-Liang
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 05/06/2012 Português
Relevância na Pesquisa
58.248843%
Most of geographic routing approaches in wireless ad hoc and sensor networks do not take into consideration the medium access control (MAC) and physical layers when designing a routing protocol. In this paper, we focus on a cross-layer framework design that exploits the synergies between network, MAC, and physical layers. In the proposed CoopGeo, we use a beaconless forwarding scheme where the next hop is selected through a contention process based on the geographic position of nodes. We optimize this Network-MAC layer interaction using a cooperative relaying technique with a relay selection scheme also based on geographic information in order to improve the system performance in terms of reliability.; Comment: in 2010 IEEE 71st Vehicular Technology Conference, 2010

Cross Layer Provision of Future Cellular Networks

Baligh, H.; Hong, M.; Liao, W. -C.; Luo, Z. -Q.; Razaviyayn, M.; Sanjabi, M.; Sun, R.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 05/07/2014 Português
Relevância na Pesquisa
58.376274%
To cope with the growing demand for wireless data and to extend service coverage, future 5G networks will increasingly rely on the use of low powered nodes to support massive connectivity in diverse set of applications and services [1]. To this end, virtualized and mass-scale cloud architectures are proposed as promising technologies for 5G in which all the nodes are connected via a backhaul network and managed centrally by such cloud centers. The significant computing power made available by the cloud technologies has enabled the implementation of sophisticated signal processing algorithms, especially by way of parallel processing, for both interference management and network provision. The latter two are among the major signal processing tasks for 5G due to increased level of frequency sharing, node density, interference and network congestion. This article outlines several theoretical and practical aspects of joint interference management and network provisioning for future 5G networks. A cross-layer optimization framework is proposed for joint user admission, user-base station association, power control, user grouping, transceiver design as well as routing and flow control. We show that many of these cross-layer tasks can be treated in a unified way and implemented in a parallel manner using an efficient algorithmic framework called WMMSE (Weighted MMSE). Some recent developments in this area are highlighted and future research directions are identified.

Cross-Layer Designs in Coded Wireless Fading Networks with Multicast

Rajawat, Ketan; Gatsis, Nikolaos; Giannakis, Georgios B.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
58.72118%
A cross-layer design along with an optimal resource allocation framework is formulated for wireless fading networks, where the nodes are allowed to perform network coding. The aim is to jointly optimize end-to-end transport layer rates, network code design variables, broadcast link flows, link capacities, average power consumption, and short-term power allocation policies. As in the routing paradigm where nodes simply forward packets, the cross-layer optimization problem with network coding is non-convex in general. It is proved however, that with network coding, dual decomposition for multicast is optimal so long as the fading at each wireless link is a continuous random variable. This lends itself to provably convergent subgradient algorithms, which not only admit a layered-architecture interpretation but also optimally integrate network coding in the protocol stack. The dual algorithm is also paired with a scheme that yields near-optimal network design variables, namely multicast end-to-end rates, network code design quantities, flows over the broadcast links, link capacities, and average power consumption. Finally, an asynchronous subgradient method is developed, whereby the dual updates at the physical layer can be affordably performed with a certain delay with respect to the resource allocation tasks in upper layers. This attractive feature is motivated by the complexity of the physical layer subproblem...

Cross-Layer Design of Wireless Multihop Networks over Stochastic Channels with Time-Varying Statistics

Stai, Eleni; Loulakis, Michail; Papavassiliou, Symeon
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 15/08/2015 Português
Relevância na Pesquisa
68.334443%
Network Utility Maximization (NUM) is often applied for the cross-layer design of wireless networks considering known wireless channels. However, realistic wireless channel capacities are stochastic bearing time-varying statistics, necessitating the redesign and solution of NUM problems to capture such effects. Based on NUM theory we develop a framework for scheduling, routing, congestion and power control in wireless multihop networks that considers stochastic Long or Short Term Fading wireless channels. Specifically, the wireless channel is modeled via stochastic differential equations alleviating several assumptions that exist in state-of-the-art channel modeling within the NUM framework such as the finite number of states or the stationarity. Our consideration of wireless channel modeling leads to a NUM problem formulation that accommodates non-convex and time-varying utilities. We consider both cases of non orthogonal and orthogonal access of users to the medium. In the first case, scheduling is performed via power control, while the latter separates scheduling and power control and the role of power control is to further increase users' optimal utility by exploiting random reductions of the stochastic channel power loss while also considering energy efficiency. Finally...

Cross-Layer Adaptive Feedback Scheduling of Wireless Control Systems

Xia, Feng; Ma, Longhua; Peng, Chen; Sun, Youxian; Dong, Jinxiang
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 29/09/2008 Português
Relevância na Pesquisa
58.679604%
There is a trend towards using wireless technologies in networked control systems. However, the adverse properties of the radio channels make it difficult to design and implement control systems in wireless environments. To attack the uncertainty in available communication resources in wireless control systems closed over WLAN, a cross-layer adaptive feedback scheduling (CLAFS) scheme is developed, which takes advantage of the co-design of control and wireless communications. By exploiting cross-layer design, CLAFS adjusts the sampling periods of control systems at the application layer based on information about deadline miss ratio and transmission rate from the physical layer. Within the framework of feedback scheduling, the control performance is maximized through controlling the deadline miss ratio. Key design parameters of the feedback scheduler are adapted to dynamic changes in the channel condition. An event-driven invocation mechanism for the feedback scheduler is also developed. Simulation results show that the proposed approach is efficient in dealing with channel capacity variations and noise interference, thus providing an enabling technology for control over WLAN.; Comment: 17 pages, 12 figures; Open Access at http://www.mdpi.org/sensors/papers/s8074265.pdf

Cross-layer Congestion Control, Routing and Scheduling Design in Ad Hoc Wireless Networks

Chen, Lijun; Low, Steven H.; Chiang, Mung; Doyle, John C.
Fonte: IEEE Publicador: IEEE
Tipo: Book Section; PeerReviewed Formato: application/pdf
Publicado em //2006 Português
Relevância na Pesquisa
58.42506%
This paper considers jointly optimal design of crosslayer congestion control, routing and scheduling for ad hoc wireless networks. We first formulate the rate constraint and scheduling constraint using multicommodity flow variables, and formulate resource allocation in networks with fixed wireless channels (or single-rate wireless devices that can mask channel variations) as a utility maximization problem with these constraints. By dual decomposition, the resource allocation problem naturally decomposes into three subproblems: congestion control, routing and scheduling that interact through congestion price. The global convergence property of this algorithm is proved. We next extend the dual algorithm to handle networks with timevarying channels and adaptive multi-rate devices. The stability of the resulting system is established, and its performance is characterized with respect to an ideal reference system which has the best feasible rate region at link layer. We then generalize the aforementioned results to a general model of queueing network served by a set of interdependent parallel servers with time-varying service capabilities, which models many design problems in communication networks. We show that for a general convex optimization problem where a subset of variables lie in a polytope and the rest in a convex set...