移动AdHoc网络的单信道媒体接入协议

AdHoc网络中的信道接入是一个比较复杂的问题,单信道接入协议是目前AdHoc网络中应用最广泛的,本文介绍了AdHoc网络中MAC协议需要解决的主要问题和设计要求,并列举分析了几种典型的基于CSMA/CA的由原端发起的单信道接入协议。最后总结了在MAC协议中常用的退避算法:二进制退避算法(BEB)和倍数增线性减算法(MILD),指出其中存在的问题。     

Energy efficient secured routing protocol for MANETs

The design of routing protocol with energy efficiency and security is a challenging task. To overcome this challenge, we propose energy-efficient secured routing protocol. The objective of our work is to provide a secured routing protocol, which is energy efficient. To provide security for both link and message without relying on the third party, we provide security to the protocol by choosing a secure link for routing using Secure Optimized Link State Routing Protocol. Each node chooses multipoint relay nodes amongst the set of one-hop neighbors, so as to reach all two-hop neighbors. The access control entity authorizes nodes announcing the node identification to the network. In addition, the access control entity signs a public key Ki, a private key ki, and the certificate Ci required by an authorized node to obtain the group key. Each node maintains a route table with power status as one of its entry. After selecting the link, on requirement of a new route, we check nodes’ power status in its routing table and then accordingly arise a route. Then, we perform group key distribution using the generated keys using a small number of messages which helps reducing energy consumption. The group key can be altered periodically to avoid nonauthorized nodes and to avoid the use of the same group key in more than some amount of data. Then, we provide communication privacy for both message sender and message recipient using Secure Source Anonymous Message Authentication Scheme. Thereby, the message sender or the sending node generates a source anonymous message authentication for message for releasing each message based on the MES scheme. Hence, our approach will provide message content authenticity without relying on any trusted third parties.     

The polarized gossip protocol for path discovery in MANETs

In this paper we present a novel probabilistic protocol for path discovery in Mobile Ad Hoc Networks (MANETs). The protocol implements what we call a polarized gossiping algorithm. While in the classical gossip algorithm each node forwards a message with the same probability, our proposal is characterized by a variable gossiping probability, which is high enough only for sustaining the spreading process towards the destination. The gossiping probability of a node is determined by the difference between its proximity to the destination and the proximity to the destination of the node from which the message was received. Differently from other proposals no external location service support, e.g., via GPS, is required. Rather, the proximity is estimated from the “inside” of the network using periodic beacons for determining the time elapsed since a node met the destination and the dwell time of a node with the destination. These information are then exploited by nodes to modulate their gossiping probability. The paper reports a mathematical model for the analysis of the algorithm along with an extensive simulation study of its implementation, which shows the suitability of the proposed solution.     

Design and analysis of RT-Ring: a protocol for supporting real-time communications

Distributed applications with quality of service (QoS) requirements are more and more used in several areas (e.g., automated factory networks, embedded systems, conferencing systems). These applications produce a type of traffic with hard timing requirements, i.e., transmissions must be completed within specified deadlines. To handle these transmissions, the communication system must use real-time protocols to provide a communication service that is able to satisfy the QoS requirements of the distributed applications. In this paper, the authors propose a new real-time protocol, called RT-Ring, able to support transmissions of both real-time and generic traffic over a ring network. RT-Ring provides both network guarantees and high network resource utilization, while ensuring the compatibility with the emerging differentiated service architectures. Network guarantees are fully proved and high network utilization is highlighted by a comparative study with the FDDI protocol. This comparison shows that RT-Ring network capacities are greater than the corresponding FDDI capacities. In fact, by assuming the FDDI frames with a length equal to the RT-Ring slot size and by using the same traffic load the authors show that the capacities of FDDI are equal to the lower bound capacities of RT-Ring.     

A paradigm for quality-of-service in wireless ad hoc networks using synchronous signaling and node states

Most limitations in mechanisms geared at achieving quality-of-service (QoS) in wireless ad hoc networking can be traced to solutions based on mapping wireless networks to a wireline paradigm of nodes and links. We contend that this paradigm is not appropriate since links are not physical entities and do not accurately represent the radio frequency (RF) media. Using the link abstraction makes arbitration of the use of the RF media cumbersome leaving only overprovisioning techniques to deliver QoS. In this paper, we argue that an appropriate paradigm should match the physics of the network. The critical resource is electromagnetic spectrum in a space; in turn, this results in a complex paradigm since the part of the spectrum-space that each node wants to use is unique to that node and its destination and will overlap with parts that other nodes may want to use creating interdependences among nodes. This paper describes protocol approaches for access and routing that seek solutions within this wireless paradigm. Access is arbitrated using synchronous signaling and topology is resolved through the dissemination of node states. This approach provides an intuitive framework that provides mechanisms that can be exploited to arbitrate RF media use and implement traffic engineering techniques to deliver QoS. Our proposed approach provides a novel way of tracking the state of the network that can serve as a unified state dissemination mechanism to simultaneously support routing, multicasting, and most QoS heuristics.     

Design and analysis of a propagation delay tolerant ALOHA protocol for underwater networks

Acoustic underwater wireless sensor networks (UWSN) have recently gained attention as a topic of research. Such networks are characterized by increased uncertainty in medium access due not only to when data is sent, but also due to significantly different propagation latencies from spatially diverse transmitters—together, we call these space-time uncertainty. We find that the throughput of slotted ALOHA degrades to pure ALOHA in such an environment with varying delay. We therefore propose handling this spatial uncertainty by adding guard times to slotted ALOHA, forming Propagation Delay Tolerant (PDT-)ALOHA. We show that PDT-ALOHA increases throughput by 17–100% compared to simple slotted ALOHA in underwater settings. We analyze the protocol’s performance both mathematically and via extensive simulations. We find that the throughput capacity decreases as the maximum propagation delay increases, and identify protocol parameter values that realize optimal throughput. Our results suggest that shorter hops improve throughput in UWSNs.     

IPBM: an energy efficient reliable interference-aware periodic broadcast messaging protocol for MANETs

Wireless Networks - Mobile ad-hoc networks (MANETs) have been widely employed in many fields including critical information delivery in open terrains as in tactical area, vehicular or disaster area...     

Design and analysis of accelerative preallocation protocol for WDMstar-coupled networks

For a wavelength division multiaccess (WDMA) system, the reservation (R-WDMA) and the preallocation (P-WDMA) protocols are two major media access methods to support packet-switched traffic. In this paper, a new media access control (MAC) protocol, accelerative preallocation WDMA (AP-WDMA), is proposed to overcome the disadvantages of P-WDMA and retain its advantages. AP-WDMA relieves the technology constraints by restricting the wavelength tunability at only one end of the communication link, removes the channel and station status tables required by R-WDMA, and uses simple arithmetics to allocate channels. Although it uses a dedicated control channel to send control-acknowledge packets, AP-WDMA employs a network management mechanism to make full use of idle time slots under different propagation and tuning delays. In addition, it is well suited to wavelength-limited networks. Three heuristic methods for channel sharing, interleaved (I), neighborhood (N), and weighted-balanced (WBH), are evaluated. Through analytical evaluations, AP-WDMA is shown to be able to improve the channel utilization and system throughput much more significantly than I-TDMA*, which is a P-WDMA protocol. We also evaluate the impact on the performance of AP-WDMA by the number of channels, the four traffic types (mesh, disconnected, ring, and uniform), the degree of channel sharing, and the unbalanced load among channels. The results show that the utilization is scalable in terms of the number of channels. Furthermore, the utilization of channels is best for the ring-traffic type and worst for the disconnected-traffic type, and the system throughput decreases as the degree of channel sharing increases. Finally, using heuristics I or WBH instead of N can resolve the unbalanced load problem under various traffic types and degrees of channel sharing     

Building a signaling protocol architecture for future mobile networks

Third-generation mobile systems are emerging. These systems will support a unified user access to a variety of services, including the existing mobile and fixed network (PSTN, N-ISDN) services, the enhanced multimedia and multiparty services envisaged for broadband networks, and personal communication services as well. The role of signaling is predominant in building a flexible, efficient, and evolving system. The aim of this paper is to provide a framework for developing a signaling protocol architecture for future mobile networks. The study especially focuses on the universal mobile telecommunication system (UMTS). Within this framework various design and operational requirements imposed on UMTS can be satisfied. A method to deal with the functional complexity of UMTS is provided. Mobile networks are viewed as integral parts of the broadband infrastructure and are built upon the IN principles.     

MQ-Routing: Mobility-, GPS- and energy-aware routing protocol in MANETs for disaster relief scenarios

Mobile-Ad-Hoc-Networks (MANETs) are self-configuring networks of mobile nodes, which communicate through wireless links. The main issues in MANETs include the mobility of the network nodes, the scarcity of computational, bandwidth and energy resources. Thus, MANET routing protocols should explicitly consider network changes and node changes into the algorithm design. MANETs are particularly suited to guarantee connectivity in disaster relief scenarios, which are often impaired by the absence of network infrastructures. Moreover, such scenarios entail strict requirements on the lifetime of the device batteries and on the reactivity to possibly frequent link failures. This work proposes a proactive routing protocol, named MQ-Routing, aimed at maximizing the minimum node lifetime and at rapidly adapting to network topology changes. The proposed protocol modifies the Q-Routing algorithm, developed via Reinforcement Learning (RL) techniques, by introducing: (i) new metrics, which account for the paths availability and the energy in the path nodes, and which are dynamically combined and adapted to the changing network topologies and resources; (ii) a fully proactive approach to assure the protocol usage and reactivity in mobile scenarios. Extensive simulations validate the effectiveness of the proposed protocol, through comparisons with both the standard Q-Routing and the Optimized Link State Routing (OLSR) protocols.     

Downlink scheduling in a cellular network for quality-of-service assurance

We consider the problem of scheduling data in the downlink of a cellular network over parallel time-varying channels, while providing quality-of-service (QoS) guarantees to multiple users in the network. We design simple and efficient admission control, resource allocation, and scheduling algorithms for guaranteeing requested QoS. In our design, a joint Knopp and Humblet (K&H)/round robin (RR) scheduler, composed of K&H scheduling and RR scheduling, utilizes both multiuser and frequency diversity to achieve capacity gain when delay constraints are loose or moderate. However, for tight delay constraints, an additional reference channel scheduler is required to obtain additional frequency diversity gain. The key advantage of our formulation is that the desired QoS constraints can be explicitly enforced by utilizing the concept of effective capacity.     

一种改进的JET光突发交换协议的实现及仿真

提出了一种支持服务质量(QoS)的改进JET(MJET)协议,并且提出了一种MJET突发包交换包格式、偏移时间的设置算法和节点控制算法,给出了用光混合突发交换(OCBS)实现此协议的仿真结果.     

Building a reference combinatorial model for MANETs

Wireless technologies and the deployment of mobile and nomadic services are driving the emergence of complex ad hoc networks that have a highly dynamic behavior. Modeling such dynamics and creating a reference model on which results could be compared and reproduced, was stated as a fundamental issue by a recent NSF workshop on networking. In this article we show how the modeling of time-changes unsettles old questions and allows for new insights into central problems in networking, such as routing metrics, connectivity, and spanning trees. Such modeling is made possible through evolving graphs, a simple combinatorial model that helps capture the behavior or dynamic networks over time.     

Design and analysis of an MAC-layer protocol for acar-to-infrastructure packet radio network

The structure of a packet radio network that must operate in an environment characterized by the presence of mobile stations and a ground network with fixed access points is defined. Each of these points consists of a ground station with a certain coverage area, which must exchange data with the mobiles over a common radio channel. Mobiles within the coverage area of a ground station must coordinate their access to the common channel. The design and analysis of the multiaccess protocol is considered, together with the procedure for the passage from a ground station coverage area to the next one along the direction of flow. The overall access strategy is described and analyzed to some extent, and simulation results are provided. The integration of this medium access control (MAC) layer protocol with existing packet radio software that also covers higher layer features is also discussed     

A signaling protocol for complex multimedia services

The author introduces a signaling protocol for user applications that invokes multimedia services provided by the EXPANSE research prototype, a broadband ISDN testbed. A generic framework that flexibly accommodates a wide variety of services involving multiple parties with heterogeneous terminals is described. The author describes the generic services supported, introduces the EXPANSE call model, discusses syntax and message flow procedures, and relates EXPANSE signaling to the ISDN signaling control part (ISCP) and long-term broadband ISDN signaling work currently under study by CCITT     

Optimal and Distributed Protocols for Cross-Layer Design of Physical and Transport Layers in MANETs

We seek distributed protocols that attain the global optimum allocation of link transmitter powers and source rates in a cross-layer design of a mobile ad hoc network. Although the underlying network utility maximization is nonconvex, convexity plays a major role in our development. We provide new convexity results surrounding the Shannon capacity formula, allowing us to abandon suboptimal high-SIR approximations that have almost become entrenched in the literature. More broadly, these new results can be back-substituted into many existing problems for similar benefit.      

An adaptive medium access control protocol using m-ary tree algorithms for quality-of-service support in single-cell ad hoc networks

Concurrent with the rapid expansion of wireless networks is an increasing interest in providing Quality-of-Service (QoS) support to them. As a consequence, a number of medium access control protocols has been proposed which aims at providing service differentiation at the distributed wireless medium access layer. However, most of them provide only average performance assurances. We argue that average performance guarantees will be inadequate for a wide range of emerging multimedia applications and “per-flow” service assurances must be provided instead. Based on m-ary tree algorithms, we propose an adaptive and distributed medium access algorithm for single-cell ad hoc networks to provide “per-flow” service assurances to flows whose QoS requirement can be expressed as a delay requirement. Both analytical and simulation experiments are conducted to assess the performance of the proposed scheme.     

A hybrid analysis/simulation for ATM performance with application to quality-of-service of CBR traffic

A discrete time queueing model for the performance of an ATM system is analyzed using matrix analytic methods. Time is segmented into slots with each slot equal to the transmission time of one ATM cell. The ATM system is modeled as a single server queue with Markovian arrivals and service time equal to one slot. The arrival process includes as a special case the superposition of on-off sources, possibly heterogeneous. The queueing model is of the M/G/1 type. By exploiting the structure of the M/G/1 type Markov chain, the complexity of the solution to the problem is reduced to only the inversion of a 2×2 matrix irrespective of the size of the Markov chain. This simplification allows us to investigate Constant Bit Rate (CBR) traffic performance (or quality-of-service) issues through a hybrid analysis/simulation approach. Specifically, we analyze the impact of on-off background traffic on the probability of consecutive cell losses, cell delay variation, and traffic shaper or playback buffer underflow and overflow probabilities of CBR traffic sources.     

NSIS: a new extensible IP signaling protocol suite

In the last few years it number of applications have emerged that can benefit from network-layer signaling (i.e., the installation, maintenance, and removal of control state in network elements). These applications include path-coupled and path-decoupled quality of service management and resource allocation, as well its network debugging, NAT, and firewall control. These applications call for an extensible and securable signaling protocol. This article discusses some of the recent standardization efforts in the IETF for it new extensible IP signaling protocol suite (NSIS). We describe the design of the NSIS protocol suite, and compare it with RSVP, the current Internet QoS signaling protocol.