Quality Of Service Degradation Research Articles

Cooperative QoS Control Scheme Based on Scheduling Information in FiWi Access Network

Fiber-wireless (FiWi) access networks comprising wireless local area networks (WLANs) and passive optical networks (PONs) have attracted much attention recently for future cyber-physical systems (CPSs). Because of the explosive growth of smart devices such as smart phones and sensors, the number of such devices has also grown phenomenally that require real time communication demanding quality of service (QoS)-centric applications for CPSs, such as smart grid, medical, and traffic control systems, which construct smart society. To deal with such situations, the FiWi access networks may be a suitable choice since they are capable of providing both wide bandwidth and flexibility. However, combining the WLAN and PON in FiWi that are inherently different networking technologies leads to inefficient data transmission in the point of junction of the WLAN and PON. Therefore, the QoS of real time communication degrades significantly. In this paper, we address this problem involving QoS degradation in the FiWi networks, and propose a QoS control scheme, which is based on cooperation between the WLAN and PON. Through computer-based simulations, we demonstrate that our proposed scheme can significantly improve the QoS performance of the FiWi access networks for CPSs.

Vertical Handover Over Intermediate Switching Framework: Assuring Service Quality for Mobile Users

Ensuring quality of service (QoS) for the mobile users during vertical handover between IEEE 802.11 wireless local area networks (WLAN) and data network provided by Ultramodern Telecommunication Systems (UMTS) is one of the key requirements for seamless mobility and transfer of existing connections from one network to another. QoS fulfillment is a complex problem and requires participation of both the mobile users as well as the connection networks. The QoS assurance criteria for existing connections can be affected by fluctuations of data rates when a user moves from the high speed WLAN network to the low speed UMTS network, even in the presence of another WLAN network in its vicinity. This can happen if the alternate WLAN network is highly loaded. Therefore handover from a high speed network to a low speed network should be avoided, whenever possible. This paper proposes a QoS based handover procedure that prioritizes the existing connection over the new connections so that rate fluctuations due to handover can be avoided if there exist another WLAN network in the range of the mobile user. Whenever the possibility of handover is detected, a pre-handover bandwidth reservation technique is used to reserve bandwidth at the alternate WLAN networks to avoid QoS degradation. The proposed scheme is implemented in Qualnet network simulator and the performance is analyzed and compared with traditional handover techniques.

A personalized QoE-aware handover decision based on distributed reinforcement learning

Recent developments in heterogeneous mobile networks and growing demands for variety of real-time and multimedia applications have emphasized the necessity of more intelligent handover decisions. Addressing the context knowledge of mobile devices, users, applications, and networks is the subject of context-aware handoff decision as a recent effort to this aim. However, user perception has not been attended adequately in the area of context-aware handover decision making. Mobile users may have different judgments about the Quality of Service (QoS) depending on their environmental conditions, and personal and psychological characteristics. This reality has been exploited in this paper to introduce a personalized user-centric handoff decision method to decide about the time and target of handover based on User Perceived Quality (UPQ) feedbacks. The UPQ degradations are mainly for the sake of (1) exiting the coverage of the serving Point of Attachment (PoA) or (2) QoS degradation of serving access network. Using UPQ metric, the proposed method obviates the necessity of being aware about rapidly varying network QoS parameters and overcomes the complexity and overhead of gathering and managing some other context information. Moreover, considering the underlying network and geographical map, the proposed method is able to inherently exploit the trajectory information of mobile users for handover decision. UPQ degradation is not only due to the user behaviour, but also due to the behaviours of others users. As such, multi-agent reinforcement learning paradigm has been considered for target PoA selection. The employed decision algorithm is based on WoLF-PHC learning method where UPQ is used as a delayed reward for training. The proposed handoff decision has been implemented under IEEE 802.21 framework using NS2 network simulator. The results have shown better performance of the proposed method comparing to conventional methods assuming regular movement of mobile users.

LOW COST TEST BENCH TO ASSESS ENERGY EFFICIENCY OF COMMUNICATIONS NETWORK EQUIPMENT

Communication network Quality of Service (QoS) degradation can lead to the consumption of additional energy to exchange information than that needed in normal conditions. If such behavior is known, network management can be more efficient and accurate, permitting to control more efficiently the energy consumption in telecommunication equipments. This study describes a test bench that can simultaneously measure the QoS parameters and energy consumption in telecommunication networks, in different traffic conditions and in different parts and components of a reduced communication network. The implemented test bench allows the accomplishment of different experiments. The QoS and power data can be presented as graphs that correlate them both. The results show that network quality of service degradation imply in more energy consumption compromising Energy Efficiency in the network.

IP Multimedia subsystem authentication protocol in LTE-heterogeneous networks

AbstractIP Multimedia Subsystem (IMS) introduces important advantages for users of LTE-femtocell heterogeneous access networks. In order to access services hosted in the IMS layer, the user has to undergo authentication procedure with the access network, followed by an authentication procedure with the IMS layer. This multi-pass authentication procedure is essential for securing IMS from malicious users, resulting in added overhead and possible quality of service degradations. The problem is further compounded when the user moves from one femtocell domain into another, which requires the authentication procedure to be repeated. To mitigate this problem, we present a lightweight, robust, and architecture-compatible IMS authentication protocol that implements a one-pass IMS procedure by promoting efficient key re-use for a mobile user. We make use of Home Node B femtocells to perform the role of IMS proxy. To verify the feasibility of using our protocol in mobile networks, an abstract model of our protocol is derived. The abstract model is emulated using Asterisk server and virtualization techniques. We also analyze the authentication delay of our proposed scheme. Numerical results reveal a reduction in user authentication delay of more than 50 percent compared to the existing authentication procedure.

Network convergence and QoS for future multimedia services in the VISION project

The emerging use of real-time 3D-based multimedia applications imposes strict quality of service (QoS) requirements on both access and core networks. These requirements and their impact to provide end-to-end 3D videoconferencing services have been studied within the Spanish-funded VISION project, where different scenarios were implemented showing an agile stereoscopic video call that might be offered to the general public in the near future. In view of the requirements, we designed an integrated access and core converged network architecture which provides the requested QoS to end-to-end IP sessions. Novel functional blocks are proposed to control core optical networks, the functionality of the standard ones is redefined, and the signaling improved to better meet the requirements of future multimedia services. An experimental test-bed to assess the feasibility of the solution was also deployed. In such test-bed, set-up and release of end-to-end sessions meeting specific QoS requirements are shown and the impact of QoS degradation in terms of the user perceived quality degradation is quantified. In addition, scalability results show that the proposed signaling architecture is able to cope with large number of requests introducing almost negligible delay.

A Fair Transmission Opportunity by Detecting and Punishing the Malicious Wireless Stations in IEEE 802.11e EDCA Network

We propose a malicious detection algorithm that permits identification of misbehaving wireless stations, and then dispenses punishment by denying an ACK packet which allows transmission by the malicious stations. The proposed algorithm is designed for an IEEE 802.11e network and is based upon detecting a change in quality of service (QoS) where a station is moved up in terms of permission to a level not justified. Non-detection causes honest stations to increase their retransmit attempts, exceeding the specified deadline in order to sustain continuous receipt of their data. Even with the coexistence of such malicious stations, our algorithm guarantees the lower bound of performance degradation to the honest stations. Also, the punished period imposed upon the malicious stations compensates the experienced degradation in QoS for the honest stations in the next transmission period. As a result, we provide fair resource sharing among the stations operating from the same access point. Our simulation within the ns-2 framework of the IEEE 802.11e enhanced distributed channel access network shows how our algorithm actually detects and adjusts the punishment phase for stations that may be misbehaving as well as stations which are misbehaving.

Call Admission Control with Resource Reservation for OFDM Networks

The scarcity of the radio resources and variable channel quality cause many challenges to the resource management for future all-IP wireless communications. One technique to guarantee a certain level of quality of service (QoS) is call admission control (CAC). Briefly, CAC is a mechanism which decides whether a new call could be admitted or rejected depending on its impacts on the current calls’ QoS. Conventional CACs such as guard channel, channel borrowing and queuing priority techniques only consider the instantaneous radio resource availabilities to make a decision on admission problem, thus they are neither able to prevent the network congestion problem nor meet the QoS requirements of different users with multi-service requirements. In this work, we propose a new CAC technique with a future look into the needed extra resources through a reservation technique to offset the changes of the channel condition due to mobility. We show that during a call session, the needed radio resources may be increased compared with the negotiated resources during call setup. Although such fluctuations are fairly low for a single call, it is not negligible when the network is congested. As a result, some ongoing calls may experience QoS degradation. We show that such a consideration is critical in orthogonal frequency division multiplexing (OFDM) wireless networks such as 3GPP LTE where the radio resources are assigned to the users depending on the channel quality. The study assumes two types of applications denoted by wide-band and narrow-band and the performance of the proposed algorithm is modeled through queuing theory and event-driven simulation approaches. The results show that such a reservation technique improves the call admission performance significantly in terms of call blocking, call drop and call QoS degradation probabilities, and it outperforms the conventional CACs with insignificant loss in network capacity.

무선 네트워크 환경에서 효과적인 영상 스트리밍을 위한 And-Or 트리 기반의 LT 부호화 심볼 패킷화 알고리즘

본 논문에서는 무선 네트워크 환경에서의 패킷 손실에 따른 영상 스트리밍 서비스의 영상 열화를 최소화 시키는 And-Or 트리 기반의 LT 패킷화 알고리즘을 제안한다. 심볼들의 효율적인 패킷화를 위해 And-Or 트리를 통한 심볼들 간의 관계를 분석하고 이 관계를 바탕으로 LT 부호화 심볼들이 포함된 패킷들 간의 의존성을 줄여 패킷손실에 대한 영향을 최소화 시키는 패킷화 알고리즘을 설계한다. 마지막으로 무선 네트워크 환경에서 영상 스트리밍 시스템을 통해 제안한 패킷화 알고리즘이 기존의 패킷화 알고리즘보다 더 향상된 복호화 성능과 영상 화질을 제공할 수 있음을 보인다. In this paper, we propose a robust And-Or tree-based Luby transform encoded symbol packetization algorithm to minimize the quality degradation of video streaming service caused by packet losses over wireless network. To achieve this goal, the relationship among Luby transform encoded symbols are analyzed by using And-Or tree, and the proposed packetization algorithm is designed to minimize packet loss effects by reducing the dependency among packets conveying Luby transform encoded symbols. Finally, experimental results are provided to show the performance of the proposed algorithm.

A Robust Luby Transform Encoding Pattern-Aware Symbol Packetization Algorithm for Video Streaming Over Wireless Network

In this paper, we propose a Luby transform encoding pattern-aware symbol packetization algorithm to minimize the quality degradation of video streaming service caused by packet losses over wireless network. To achieve this goal, the relationship among Luby transform encoded symbols is analyzed based on Luby transform encoding pattern, and the proposed packetization algorithm is designed to minimize packet loss effects by reducing the dependency among packets conveying Luby transform encoded symbols. Finally, experimental results are provided to show the performance of the proposed algorithm.

시뮬레이션을 이용한 대규모 스마트 TV 서비스 제공을 위한 사용자 그룹핑 알고리즘 성능 분석

ABSTRACTSmart TV System will lead to drastic change of communication and media industries as one of the emerging next generation network services. However, when the number of concurrent users increases rapidly, the issue of service quality degradation occurs because providing services to many users simultaneously stresses both the server and the network. The server limitation can be circumvented by deploying server clusters. but the network limitation is far less easy to cope with, due to the difficulty in determining the cause and location of congestion and in provisioning extra resources. In order to alleviate these problems, a number of schemes have been developed. Prior works mostly focus on reducing user-centric performance metrics of individual connection, such as the round-trip time(RTT), downloading time or packet loss rate, but tend to ignore the network loads caused by the concurrent connections or global network load balance. In this work, we make an in-depth investigation on the issue of user grouping for massive Smart TV services through simulations on actual Internet test-bed, PlanetLab.

OFDMA channel aware error-resilient mobile streaming video service over mobile WiMAX

The growing demands for advanced mobile multimedia let the wireless mobile Internet access be developed rapidly. The Mobile WiMAX (IEEE 802.16e) is capable of providing high data rate and flexible Quality of Service (QoS) mechanisms. However, one of killer applications, mobile streaming video service from mobile station (MS) to fixed internet network can't still avoid a traditional QoS degradation problem caused by unreliable mobile channel environment. The previous researches show that streaming video service based on downward cross-layer design over OFDMA channel has improved robust features to channel errors, but requires modifications of the existing schedulers, packet ordering, and channel allocation strategies in base station (BS). Now, our goal is that we develop a high error resilient and robust method to channel errors on the OFDMA mobile video device without the modification of conventional functions in WiMAX BS. In this paper, we introduce OFDMA channel aware error resilient video coding method using an upward cross-layer design. Through the extensive simulation results, we prove that the proposed channel-aware intra-refresh coding can recover video damages more efficiently than traditional intra-refresh one over OFDMA channel environment. This error resilience feature can be adapted to all types of streaming video server devices.

VoIP Quality Measurement System Using Flow Mediation for Large-Scale IP Networks

We present the development of a VoIP quality of service (QoS) measurement system that enables operators to diagnose a QoS degradation segment. Our system uses a flow-based passive measurement method to fulfill the requirement for QoS measurement in large-scale IP networks. In particular, we adopt an access control list (ACL)-based filtering function that selects traffic to monitor and develop a function for correlating signals and media data records. This correlation function is required to dynamically configure ACL-based filtering for monitoring media streams whose port numbers are determined by a signaling protocol. To improve the scalability of existing measurement systems, we also develop a hardware-based filtering engine on a commercial switch as well as a mediation box that performs QoS calculation based on traffic records exported by the engine in a distributed manner. We demonstrate the feasibility of the measurement system by evaluating a prototype system.

On the Handling of Node Failures: Energy-Efficient Job Allocation Algorithm for Real-time Sensor Networks

Wireless sensor networks are usually characterized by dense deployment of energy constrained nodes. Due to the usage of a large number of sensor nodes in uncontrolled hostile or harsh environments, node failure is a common event in these systems. Another common reason for node failure is the exhaustion of their energy resources and node inactivation. Such failures can have adverse effects on the quality of the real-time services in Wireless Sensor Networks (WSNs). To avoid such degradations, it is necessary that the failures be recovered in a proper manner to sustain network operation. In this paper we present a dynamic Energy efficient Real-Time Job Allocation (ERTJA) algorithm for handling node failures in a cluster of sensor nodes with the consideration of communication energy and time overheads besides the nodes' characteristics. ERTJA relies on the computation power of cluster members for handling a node failure. It also tries to minimize the energy consumption of the cluster by minimum activation of the sleeping nodes. The resulting system can then guarantee the Quality of Service (QoS) of the cluster application. Further, when the number of sleeping nodes is limited, the proposed algorithm uses the idle times of the active nodes to engage a graceful QoS degradation in the cluster. Simulation results show significant performance improvements of ERTJA in terms of the energy conservation and the probability of meeting deadlines compared with the other studied algorithms.

Effective distributed service architecture for ubiquitous video surveillance

Video surveillance systems are playing an important role to protect lives and assets of individuals, enterprises and governments. Due to the prevalence of wired and wireless access to Internet, it would be a trend to integrate present isolated video surveillance systems by applying distributed computing environment and to further gestate diversified multimedia intelligent surveillance (MIS) applications in ubiquity. In this paper, we propose a distributed and secure architecture for ubiquitous video surveillance (UVS) services over Internet and error-prone wireless networks with scalability, ubiquity and privacy. As cloud computing, users consume UVS related resources as a service and do not need to own the physical infrastructure, platform, or software. To protect the service privacy, preserve the service scalability and provide reliable UVS video streaming for end users, we apply the AES security mechanism, multicast overlay network and forward error correction (FEC), respectively. Different value-added services can be created and added to this architecture without introducing much traffic load and degrading service quality. Besides, we construct an experimental test-bed for UVS system with three kinds of services to detect fire and fall-incident features and record the captured video at the same time. Experimental results showed that the proposed distributed service architecture is effective and numbers of services on different multicast islands were successfully connected without influencing the playback quality. The average sending rate and the receiving rates of these services are quite similar, and the surveillance video is smoothly played.

Surmounting Data Overflow Problems in the Collection of Information for Emerging High-Speed Network Systems

Emerging high-speed network systems are capable of transporting and delivering data at rates faster than hardware and software components can economically process them. The result is data overflow in which performance information that is critical for effective network system monitoring and management may be lost, thereby leaving the system vulnerable to quality of service degradation and the service provider unable to meet customer service level agreements. Service providers seek a solution to this problem that minimizes the amount of high-speed, high-cost electronics required to comprehensively recognize such information. This paper addresses the challenge of surmounting data overflow problems in the collection of information by introducing a new procedure to transform finite state recognizers into new machines that can recognize bit-level information as it passes a monitoring point while operating slower than bit-rate for implementation in reconfigurable hardware, such as RAM and Field Programmable Gate Arrays. This is accomplished by mapping N-bit sets from the input stream into new symbols that can be processed at rate 1/N while also generating N-bit output symbols. The process is illustrated by implementation examples, and a time versus space tradeoff analysis is presented.

Reputation-Enabled Self-Modification for Target Sensing in Wireless Sensor Networks

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Wireless sensor networks provide new tools for sensing physical environments. However, the general existence of faulty sensor measurements in networks will cause degradation of the network service quality and huge burden of the precious energy. While cryptography-based approaches are helpless of information generation, reputation systems are demonstrated of positive results. In this paper, we investigate the benefits of a distributed reputation system in target localization. A node reputation is defined as its measurement performance and is computed by the Dirichlet distribution. By assuming the sensing model of each node to be mixed Gaussian, we use reputation to estimate parameters of the sensing model and modify a node's original measurement. We also develop a reputation-based local voting algorithm to filter the untrustworthy data and then estimate the target location by a particle swarm optimization algorithm. To assure energy efficiency of the proposed approach, we use a reputation-based model to indicate the information importance of each data packet and ensure that a more important packet can be delivered with higher reliability. Finally, we experimentally evaluate the reputation system and demonstrate its accuracy and energy efficiency. </para>

SCTP for robust and flexible IP anycast services

IP anycast is a powerful network layer mechanism that can be used for transparent communications between clients and a distributed service infrastructure. Unfortunately, large-scale deployment of IP anycast would cause a number of severe problems, including excessive routing table growth and potential routing instability. In order to solve these problems, a number of overlay network architectures have been proposed over the last years. In this paper we show that the robustness of anycast services provided via such anycast architectures can be significantly improved by using SCTP transport layer facilities. More specifically, the proposed approach adds the following important features to existing anycast overlays: Robustness to anycast overlay node failure or network reconfiguration, seamless anycast service delivery to mobile clients, and true stateful anycast communications over an entirely stateless infrastructure. Furthermore, we argue that the number of overlay nodes can be drastically reduced in comparison with the earlier architectures, without degrading service quality or increasing the end-to-end path stretch.

Improving Quality-of-Service in Wireless Sensor Networks by Mitigating “Hidden-Node Collisions”

Wireless sensor networks (WSNs) emerge as underlying infrastructures for new classes of large-scale networked embedded systems. However, WSNs system designers must fulfill the quality-of-service (QoS) requirements imposed by the applications (and users). Very harsh and dynamic physical environments and extremely limited energy/computing/memory/communication node resources are major obstacles for satisfying QoS metrics such as reliability, timeliness, and system lifetime. The limited communication range of WSN nodes, link asymmetry, and the characteristics of the physical environment lead to a major source of QoS degradation in WSNs-the ldquohidden node problem.rdquo In wireless contention-based medium access control (MAC) protocols, when two nodes that are not visible to each other transmit to a third node that is visible to the former, there will be a collision-called hidden-node or blind collision. This problem greatly impacts network throughput, energy-efficiency and message transfer delays, and the problem dramatically increases with the number of nodes. This paper proposes H-NAMe, a very simple yet extremely efficient hidden-node avoidance mechanism for WSNs. H-NAMe relies on a grouping strategy that splits each cluster of a WSN into disjoint groups of non-hidden nodes that scales to multiple clusters via a cluster grouping strategy that guarantees no interference between overlapping clusters. Importantly, H-NAMe is instantiated in IEEE 802.15.4/ZigBee, which currently are the most widespread communication technologies for WSNs, with only minor add-ons and ensuring backward compatibility with their protocols standards. H-NAMe was implemented and exhaustively tested using an experimental test-bed based on ldquooff-the-shelfrdquo technology, showing that it increases network throughput and transmission success probability up to twice the values obtained without H-NAMe. H-NAMe effectiveness was also demonstrated in a target tracking application with mobile robots over a WSN deployment.

Throughput and QoS improvement via fixed relay station cooperated beam-forming

Throughput and quality-of-service (QoS) over multicell environments are two of the most challenging issues that must be addressed when developing next generation wireless network standards. Currently, multiple-input/multiple-output (MIMO), inter-cell coordination and multi-hop relay technologies are viable options for improving channel capacity or coverage extension. Nevertheless, severe QoS degradation occurs in the outer region of multi-cells due to significant interference from neighboring cells or relay stations, thereby limiting overall performance. This paper describes an effective technique, fixed relay station cooperated beam-forming (FCBF), which combines MIMO, multi-hop relay and multi-cell coordination. Simulated testing of FCBF demonstrates an increase of 10% in the average sum-rate and a decrease of 25% in the outage probability compared with conventional techniques. In particular, throughput at the cell boundary is remarkably increased with FCBF compared with traditional beam-forming technologies.