Support Of Real-time Services Research Articles

Proposal and Investigation of a Lite Time Sensitive Networking Solution for the Support of Real Time Services in Space Launcher Networks

Proposal and Investigation of a Lite Time Sensitive Networking Solution for the Support of Real Time Services in Space Launcher Networks

RANCE: A Randomly Centralized and On-Demand Clustering Protocol for Mobile Ad Hoc Networks

LEACH-like clustering protocols focus mainly on the low-power, low-rate, and low-wakeup network applications, and work in a multiround clustering strategy that causes frequent handovers of cluster heads (CHs), thus less support for real-time services that require stable cluster topologies. Besides, these protocols are faced with respective drawbacks, such as suboptimality of selected heads, costly node-base station (BS) energy overheads, lack of runtime cluster maintenance, etc. This article proposes RANCE, a randomly centralized and on-demand clustering protocol, aiming at prolonging nodes’ clustered time to support internodes collaboration while being energy efficient in mobile ad hoc networks. First, RANCE designs a randomly centralized CH selection mechanism in which every node in the local wireless network is eligible to initiate the centralized CH selection, so that the self-organizing characteristics of mobile ad hoc nodes can be utilized for head selection optimization. Second, taking into account the wireless volatility caused by changes of topology, obstacles, signal strength, etc., the fine-grained cluster relationships maintenance is provided by means of multilevel aliveness and adaptive bidirectional heartbeat packets. Third, RANCE works in an event-driven and on-demand manner instead of a time-triggered manner in LEACH-like protocols, to reduce the impact on continuous services caused by frequent CH handovers among all nodes. Simulation results show that RANCE provides longer clustered time (over 99% of nodes’ lifetime in networks more than 100 nodes) and good clustering scalability with high consistency at minimum energy cost, and exhibits good potentials in mobile wireless environments that are infrastructureless/poor for continuous missions.

Convergence of Information-Centric Networks and Edge Intelligence for IoV: Challenges and Future Directions

Recently the Internet of Vehicles (IoV) has become a promising research area in the field of the Internet of Things (IoT), which enables vehicles to communicate and exchange real-time information with each other, as well as with infrastructure, people, and other sensors and actuators through various communication interfaces. The realization of IoV networks faces various communication and networking challenges to meet stringent requirements of low latency, dynamic topology, high data-rate connectivity, resource allocation, multiple access, and QoS. Advances in information-centric networks (ICN), edge computing (EC), and artificial intelligence (AI) will transform and help to realize the Intelligent Internet of Vehicles (IIoV). Information-centric networks have emerged as a paradigm promising to cope with the limitations of the current host-based network architecture (TCP/IP-based networks) by providing mobility support, efficient content distribution, scalability and security based on content names, regardless of their location. Edge computing (EC), on the other hand, is a key paradigm to provide computation, storage and other cloud services in close proximity to where they are requested, thus enabling the support of real-time services. It is promising for computation-intensive applications, such as autonomous and cooperative driving, and to alleviate storage burdens (by caching). AI has recently emerged as a powerful tool to break through obstacles in various research areas including that of intelligent transport systems (ITS). ITS are smart enough to make decisions based on the status of a great variety of inputs. The convergence of ICN and EC with AI empowerment will bring new opportunities while also raising not-yet-explored obstacles to realize Intelligent IoV. In this paper, we discuss the applicability of AI techniques in solving challenging vehicular problems and enhancing the learning capacity of edge devices and ICN networks. A comprehensive review is provided of utilizing intelligence in EC and ICN to address current challenges in their application to IIoV. In particular, we focus on intelligent edge computing and networking, offloading, intelligent mobility-aware caching and forwarding and overall network performance. Furthermore, we discuss potential solutions to the presented issues. Finally, we highlight potential research directions which may illuminate efforts to develop new intelligent IoV applications.

A Real-Time Software Defined Networking Framework for Next-Generation Industrial Networks

Industry 4.0 brings in a whole set of new requirements to engineering industrial systems, with notorious impact at the networking layer. A key challenge posed by Industry 4.0 is the operational flexibility needed to support on-the-fly reconfiguration of production cells, stations, and machines. At the networking layer, this flexibility implies dynamic packet handling, scheduling, and dispatching. SoftwareDefined Networking (SDN) provides this level of flexibility in the general Local Area Network (LAN) domain. However, its application in the industry has been hindered by a lack of support for real-time services. This paper addresses this limitation, proposing an extended SDN OpenFlow framework that includes realtime services, leveraging existing real-time data plane Ethernet technologies. We show the OpenFlow enhancements, a real-time SDN controller, and experimental validation and performance assessment. Using a proof-of-concept prototype with 3 switches and cycles of 250μs, we could achieve 1μs jitter on timetriggered traffic and a reconfiguration time between operational modes below 10ms.

Intra-flow Contention Scheme for Improving QoS in WLAN

With the increasing popularity of wireless local area network(WLAN),the demand for multimedia services encompassing VoIP, multimedia streaming and interactive gaming is increasing rapidly. The real-time services require stringent Quality of Service (QoS) guarantees for effective communication. While a lot of research has dealt with providing QoS support for real-time services in traditional wired networks, the shared and broadcast nature of the wireless medium necessitates the design of new solutions for wireless networks. In wireless networks, unlike wired networks, the communication from one node will consume the bandwidth of the neighboring nodes and hence the shared bandwidth can be easily over-utilized. Therefore, to provide an acceptable level of QoS for the real-time services, it is necessary to control the utilization of the shared bandwidth. In this paper , we propose an efficient admission control scheme named Intra-flow contention scheme with CAC-OLSR routing protocol for WLAN networks which aims at preserving the QoS for all the admitted flows by employing a low overhead threshold mechanism. We describe several alternatives for the design of IAC and compare the performance of these alternatives using simulation results.

Quality of Service Analysis for the Real-Time Secondary Users in Cognitive Radio Cellular Networks

Cognitive radio technology can improve the spectrum utilization in wireless networks by providing the capability for the secondary users to opportunistically use the frequency spectrum which is originally dedicated to the licensed users. In this paper the quality of service parameters for the real-time (RT) secondary users are analyzed in an overlay cognitive radio cellular network. RT packets are delay sensitive and can tolerate a limited amount of waiting time. Otherwise they will be useless and hence will be dropped. On the other hand, the availability of the frequency channels for SUs in cognitive radio networks (CRNs) depends on the activity of licensed users. Therefore, the support of RT services in CRNs requires elaborate considerations in various functionalities of the network. Here a practical cellular structure for the network is considered. Furthermore, a packet scheduling scheme is proposed and an analytical framework is developed for the performance analysis of RT secondary users. The effect of errors of spectrum sensing is also taken into account in the performed analysis. The analytical results are verified by simulations. The obtained results are very helpful for the support of RT traffic in cellular CRNs.

A Call Admission Control Scheme for Multimedia Support Over IEEE 802.11 Wireless LANs

These days there is an increasing interest for VoIP over wireless LANs. QoS support for real-time services like voice in the IEEE 802.11 WLAN is an important issue. Since IEEE 802.11 uses contention based MAC protocol – the distributed coordination function DCF, it is difficult to support the strict QoS requirements for voice in these networks. In this thesis a call admission scheme called “CAC” is proposed to achieve this goal, without changing the basic channel access mechanism of IEEE 802.11. CAC scheme regulates the arriving traffic in the wireless network to efficiently coordinate the medium among the contending traffic sources so that the network operates at optimal point, supporting the QoS requirements as well as providing better channel utilization. In this proposal, majority of available bandwidth is allocated to voice sources and remaining small amount is allocated for non real-time data traffic. It is expected that the proposed CAC scheme can well support strict QoS requirements, such as high throughput and low delay at the same time achieve a high channel utilization.

A holistic approach to minimizing handover latency in heterogeneous wireless networking environments

One major requirement that has to be satisfied in heterogeneous wireless networking environments is the support for real time services and applications that are becoming increasingly popular and should be effectively supported end-to-end. Thus special emphasis should be given for the design and dimensioning of the handover procedure which becomes a challenge when a user is moving within heterogeneous systems. In this work we deal with the problem of handover time minimization for bandwidth demanding and real time services in 4th generation wireless communications systems. In particular we present a framework for handover execution as well as its associated procedures that are activated adaptively to the available resources for achieving bounded latency, together with their performance which is evaluated via simulations.

Quality of service provisioning for distributed data center inter-connectivity enabled by network virtualization

Today’s service platform or Cloud service models, such as Infrastructure-as-a-Service (IaaS), enable customers to deploy and execute applications on an on-demand available infrastructure. Such platforms reduce operational expenses for the service provider and lower the entry barrier for small and medium enterprises. However, current commercial solutions do not provide sufficient quality of service (QoS) guarantees for some applications. For example, they do not support various interactive real-time applications. In this paper, we introduce a way overcome these current Cloud service limitations. We show how to provide and guarantee quality of service requirements for resource networks within an IaaS framework. Our work has focused on methods for network resource management and flow control as well as QoS models. We have developed a framework that enables QoS support for real-time services executing within an IaaS environment.

Service architectures in H.323 and SIP: A comparison

One of the major challenges for next-generation IP networks is to provide new, attractive multimedia services. This includes traditional telephony (voice over IP) and the interworking with legacy telephony systems. In addition to the general problems regarding the support of realtime services in the IP network, e.g., quality of service, voice over IP focuses on the control of advanced features such as supplementary services well known from telephony and on the mechanisms for their fast and efficient development and deployment. The two most promising approaches in the area of multimedia over IP are the protocol suites H.323 (ITU-T) and SIP (IETF). Several comparisons of these two protocols have already been published, but comparisons of their service architectures have been rarely addressed. This tutorial describes and compares the service architectures of H.323 and SIP. The basic protocol architectures are explained, followed by an in depth evaluation of the service implementation mechanisms. The analyses focus mainly on the control of telephony supplementary services in H.323 and SIP and are backed up by detailed examples. Although the two protocol architectures are quite similar, it is shown that there are considerable differences regarding their supplementary service architectures. H.323 (together with H.450) has been especially focused on supplementary services, smooth interworking with the PSTN, and interoperability between different implementations. In this respect, it has clear advantages for IP telephony applications. SIP has been designed with a broader scope, providing more generic syntax and semantics regarding feature definition and session description. Since the SIP standards do not describe details of possible application and service features, this bears the danger of interoperability problems, e.g, for supplementary services. SIP offers advantages for non voice over IP services and applications. A coexistence of both protocols can be foreseen, stressing the importance of interworking between them.

TeleMIP: telecommunications-enhanced mobile IP architecture for fast intradomain mobility

This article first surveys existing protocols for supporting IP mobility and then proposes an extension to the mobile IP architecture, called TeleMIP. Our architecture attempts to achieve smaller handoff latency by localizing the scope of most location update messages within an administrative domain or a geographical region. TeleMIP is intended for use in evolving third-generation wireless networks, and introduces a new logical entity, called the mobility agent, which provides a mobile node with a stable point of attachment in a foreign network. While the MA is functionally similar to conventional foreign agents, it is located at a higher level in the network hierarchy than the subnet-specific FAs. Location updates for intradomain mobility are localized only up to the MA; transmission of global location updates are necessary only when the mobile changes administrative domains and/or geographical regions. By permitting the use of private or locally scoped addresses for handling intradomain mobility, TeleMIP allows efficient use of public address space. Also, by reducing the frequency of global update messages, our architecture overcomes several drawbacks of existing protocols, such as large latencies in location updates, higher likelihood of loss of binding update messages, and loss of inflight packets, and thus provides better mobility support for real-time services and applications. The dynamic creation of mobility agents (in TeleMLP) permits the use of load balancing schemes for the efficient management of network resources.

Performance of Single-Hop WDM LANs Supporting Real-Time Services

Optical wavelength division multiplexing (WDM) local area networks are capable of fulfilling the enormous bandwidth demands of present and future applications. Up to now, the WDM LAN world is primarily dominated by the passive-star coupler (PSC) based architectures, for which many medium access control (MAC) protocols have been proposed. However, an arrayed waveguide grating multiplexer (AWGM)-based single-hop WDM network seems to be a very promising alternative. One of the most critical issues in designing next generation photonic LANs is the support of real-time services for applications with different time constraints. In this paper, different basic access protocols for the PSC as well as AWGM-based single-hop WDM LANs are considered and their performance in supporting real-time traffic is analyzed by means of extensive computer simulations. For evaluation of real-time performance, packet drop rates and deadline missing rates are taken as performance measures. Furthermore, new real-time message scheduling schemes are proposed which improve the performance of protocols accommodating mixed traffic. They can be differentiated between message scheduling at the source nodes’ transmit queues and scheduling based upon control information from a control channel. It is shown that both types of priority scheduling significantly improve the overall real-time performance.

Integrated services packet networks with mobile hosts: architecture and performance

This paper considers the support of real-time services to mobile users in an Integrated Services Packet Network. In the currently existing architectures, the service guarantees provided to the mobile hosts are mobility dependent, i.e., mobile hosts experience wide variation in the quality of service and often service disruption when hosts move from one location to another. The network performance degrades significantly when mobile hosts are provided with mobility independent service guarantees. In this paper we have proposed a service model for mobile hosts that can support adaptive applications which can withstand service degradation and disruption, as well as applications which require mobility independent service guarantees. We describe an admission control scheme for implementing this service model and evaluate its performance by simulation experiments. Simulation results show that, if sufficient degree of multiplexing of the mobility dependent and independent services are allowed, the network does not suffer any significant performance degradation and in particular our admission control scheme achieves high utilization of network resources.

Modelling the delivery of multimedia services over Hiperlan

Results from a detailed model of multimedia service delivery using the Hiperlan wireless LAN standard are reported. Hiperlan is shown to provide reasonable quality of service support for real-time services in several likely scenarios. However, the channel access prioritisation mechanism is shown to reduce to effectively two levels under conditions of network overload.