Quality Of Service Degradation Research Articles

Performance Analysis of Location Privacy Preserving Scheme for MANETs

We consider the problem of preserving node's location privacy which is essential for minimizing the attacks during multi-hop routing in MANETs. As by intercepting and analyzing the transmitted packets, intermediate nodes (conventionally, assumed to be trustworthy) can track sender and receiver nodes, and can also trace the route between them. Earlier approaches attempts to preserve the location privacy by changing node-IDs or masking the location information, but results in high cost and degradation of service quality. To overcome these drawbacks, this paper presents: 1) a novel rough set based Location Privacy Preserving (LPP) scheme during route establishment; and 2) an efficient Data Transfer scheme for Location Privacy Preserving based Routes (DTLPPR) during data transfer. Analysis of trustworthiness of neighbor nodes using Discrete Time Markov Chain, and proposed scheme in terms of location privacy and route untraced ability is presented. Analytical work is validated using simulations.

Provider selection and task allocation in telecommunications with QoS degradation policy

The information age that we are living in is characterized by exponentially increasing needs and corresponding means to access, transmit and use data in a variety of business settings. Fast growing demand, which is translated to market opportunities, has led to the emergence of many new and well-established firms entering into the telecommunications market, resulting in a crowded, highly competitive business environment with numerous providers and carriers offering a wide range of data services. Today’s firms use telecommunication networks in a variety of ways to carry out their daily communications such as video conferencing, voice over IP and other data-intensive transmissions. In this paper, we report on a study in which we investigate a cost optimization problem that a firm encounters when acquiring network bandwidth from a telecommunication market that consists of many backbone providers offering different combinations of pricing policies and quality of service (QoS) levels. After the acquisition of network resources (bandwidth), firms allocate these resources to their daily data transmissions (tasks) according to the QoS requirement of the tasks. In an optimal allocation scheme, it is generally presumed that each task has to be assigned to a network resource which is capable of providing an equal or higher level of QoS than required by the task. However, it is shown with the proposed heuristic approach (presented herein) that QoS degradations during the allocation of tasks can lead to more favorable outcomes, especially when certain cost penalty policies are applied to the reduction of QoS requirements.

Complex log file synthesis for rapid sandbox-benchmarking of security- and computer network analysis tools

Today Information and Communications Technology (ICT) networks are a dominating component of our daily life. Centralized logging allows keeping track of events occurring in ICT networks. Therefore a central log store is essential for timely detection of problems such as service quality degradations, performance issues or especially security-relevant cyber attacks. There exist various software tools such as security information and event management (SIEM) systems, log analysis tools and anomaly detection systems, which exploit log data to achieve this. While there are many products on the market, based on different approaches, the identification of the most efficient solution for a specific infrastructure, and the optimal configuration is still an unsolved problem. Today׳s general test environments do not sufficiently account for the specific properties of individual infrastructure setups. Thus, tests in these environments are usually not representative. However, testing on the real running productive systems exposes the network infrastructure to dangerous or unstable situations. The solution to this dilemma is the design and implementation of a highly realistic test environment, i.e. sandbox solution, that follows a different – novel – approach. The idea is to generate realistic network event sequence (NES) data that reflects the actual system behavior and which is then used to challenge network analysis software tools with varying configurations safely and realistically offline. In this paper we define a model, based on log line clustering and Markov chain simulation to create this synthetic log data. The presented model requires only a small set of real network data as an input to understand the complex real system behavior. Based on the input׳s characteristics highly realistic customer specified NES data is generated. To prove the applicability of the concept developed in this work, we conclude the paper with an illustrative example of evaluation and test of an existing anomaly detection system by using generated NES data.

Resource Allocation Based on the Type of Handovers in Overlaid Macro-Femto Networks

In this paper we propose the resource allocation scheme for the overlaid macro-femtocell networks, which considers the type of handovers such as the inter-macrocell, macrocell-to-femtocell, femtocell-to-macrocell, or inter-femtocell in order to guarantee Quality of Service (QoS) and expand the accommodation capacity. Our proposed scheme takes into account the movement of mobile terminals, the QoS degradation, or the load control which trigger handovers in the overlaid networks, before it allocates resources dynamically. Moreover it considers QoS requirements of realtime or non-realtime mobile multimedia services such as video communication, Video on Demand (VoD) and dataa services. Simulation results show that our scheme provides better performances than the conventional one with respect to the outage probability, data transmission throughput and handover failure rate.

Grid Energy Consumption and QoS Tradeoff in Hybrid Energy Supply Wireless Networks

Hybrid energy supply (HES) wireless networks have recently emerged as a new paradigm to enable green networks, which are powered by both the electric grid and harvested renewable energy. In this paper, we will investigate two critical but conflicting design objectives of HES networks, i.e., the grid energy consumption and quality of service (QoS). Minimizing grid energy consumption by utilizing the harvested energy will make the network environmentally friendly, but the achievable QoS may be degraded due to the intermittent nature of energy harvesting. To investigate the tradeoff between these two aspects, we introduce the total service cost as the performance metric, which is the weighted sum of the grid energy cost and the QoS degradation cost. Base station assignment and power control is adopted as the main strategy to minimize the total service cost, while both cases with non-causal and causal side information are considered. With non-causal side information, a Greedy Assignment algorithm with low complexity and near-optimal performance is proposed. With causal side information, the design problem is formulated as a discrete Markov decision problem. Interesting solution structures are derived, which shall help to develop an efficient monotone backward induction algorithm. To further reduce complexity, a Look-Ahead policy and a Threshold-based Heuristic policy are also proposed. Simulation results shall validate the effectiveness of the proposed algorithms and demonstrate the unique grid energy consumption and QoS tradeoff in HES networks.

Multi Agent System based Tcp using Seamless Internet Access for Vanet

In this project implement seamless and efficient WIFI-based Internet access from moving vehicles. In our implementation, a group of aps are employed to communicate with a client (called ‘AP diversity’), and the transmission succeeds if any AP in the group accomplishes the delivery with the client (called ‘opportunistic transmission’). Such AP diversity and opportunistic transmission are exploited to overcome the high packet loss rate, which is achieved by configuring all the aps with the same MAC and IP addresses. The cellular networks have been proven to be insufficient for the surging amount of data from Internet-enabled mobile devices. Due to the explosive growth of the subscriber number and the mobile data, cellular networks are suffering overload, and the users are experiencing service quality degradation. With such a configuration, a client gets a graceful illusion that only one (‘virtual’) AP exists, and will always be associated with this ‘virtual’ AP. Uplink communications, when the client transmits a packet to the virtual AP, actually multiple aps within its transmission range are able to receive it. seamless in the sense that any user can use it and maintain his workspace, including all existing network connections without manual configuration and with minimal network overhead. In downlink, a packet destined for a client is first pushed to a group of APs through multicast. This AP group is maintained dynamically to follow the moving client.

Experimental evaluation of the uplink dynamic range threshold

Despite the orthogonality of LTE’s uplink transmission, it can happen that signals which are received at the base station with low power are drown out by strong signals from other users. Reason is the limited quantization resolution of the base station’s analog-to-digital converter. Since this effect causes a quality of service degradation for users at the cell edge, the dynamic receive power range of uplink signals arriving at the base station should be upper limited. However, setting an adequate upper limit for the dynamic receive power range is not trivial since many effects, such as quantization noise, fast fading etc., decrease the dynamic range which the analog-to-digital converter can handle in theory. In this paper, we measure the maximal uplink dynamic receive power range, denoted as uplink dynamic range threshold, for our LTE-like measurement setup by monitoring the uplink bit-error-rate of a first user while decreasing its transmit power during the presence of a second adjacently scheduled user with fixed transmit power. As the measured threshold is 31.4±7.6 dB, we can conclude that a link-budget-based estimation of the dynamic receive power range, which has been published previously, is accurate since its result coincides with the measurement.

Supporting Time-Based QoS Requirements in Software Transactional Memory

Software transactional memory (STM) is an optimistic concurrency control mechanism that simplifies parallel programming. However, there has been little interest in its applicability to reactive applications in which there is a required response time for certain operations. We propose supporting such applications by allowing programmers to associate time with atomic blocks in the form of deadlines and quality-of-service (QoS) requirements. Based on statistics of past executions, we adjust the execution mode of transactions by decreasing the level of optimism as the deadline approaches. In the presence of concurrent deadlines, we propose different conflict resolution policies. Execution mode switching mechanisms allow the meeting of multiple deadlines in a consistent manner, with potential QoS degradations being split fairly among several threads as contention increases, and avoiding starvation. Our implementation consists of extensions to an STM runtime that allow gathering statistics and switching execution modes. We also propose novel contention managers adapted to transactional workloads subject to deadlines. The experimental evaluation shows that our approaches significantly improve the likelihood of a transaction meeting its deadline and QoS requirement, even in cases where progress is hampered by conflicts and other concurrent transactions with deadlines.

무선 네트워크에서 비디오 스트리밍의 버퍼 오버플로우를 해결하기 위한 토큰버킷 기법

In wireless network, the amount of video streaming packet information in receiver replay buffer can be varied according tothe wireless network condition. By the effect, unforeseeable delay and jitter are generated and then busty video traffics can be made. If the amount of buffer information coming in receiver replay buffer is larger than the amount of a specific buffer information, buffer overflow is generated. Such a problem makes the image skip effect and packet loss, and then causes the quality degradation and replay discontinuity of the video streaming service in destination receiver. To solve the buffer overflow problem, this paper applies the token bucket for the busty traffic to the receiver terminal and analyzes the effect of the token bucket. The simulation result using NS-2 and JSVM shows that the proposed scheme with the token bucket has significantly better performance than the conventional scheme without the token bucket in terms of overflow generation number, packet loss rate and PSNR.

Virtual Spectrum Hole: Exploiting User Behavior-Aware Time-Frequency Resource Conversion

In this paper, to address network congestion stemmed from traffic generated by advanced user equipment, we propose a novel network resource allocation strategy, i.e., time-frequency resource conversion (TFRC), via exploiting user behavior, a specific kind of context information. The key idea is to use radio resources mainly on the traffic/connection to which a user pays attention. The TFRC withdraws spectrum resources strategically from connection(s) not focused on by the user, providing reuseable spectrum called “virtual spectrum hole”. Considering an LTE-type cellular network, a double-threshold guard channel policy is proposed to facilitate the implementation of TFRC. An analytical model is established to study benefits of exploiting TFRC in terms of call-level performance, including new call blocking, handoff call dropping, and recovering call dropping probabilities. Numerical results demonstrate the effectiveness of the proposed approach, in increasing the cell capacity (maximum user number per cell) while limiting potential service quality degradation introduced by the newly proposed technique.

A Novel QoS Mapping Mechanism in Integrated UMTS/WLANs

Due to the problem of different QoS granularity in integrated UMTS/WLANs, how we construct effective QoS mapping mechanism for user satisfaction is essential during the changes of access networks, so called, handoffs. So in this paper, a novel dynamical QoS mapping mechanism based on Application Service Map (ASM) is proposed in order to support end to end QoS and minimize the service quality degradations. Based on the access network corresponding classification methods, all services can be categorized by priority and subdivides each grade of service into three sub-levels based on ASM. The proposed mechanism contains a two-way QoS mapping adjustment mechanism and it can dynamically adjust the QoS mapping relationship to optimize the allocation of resource according to present load condition of network. And a two-level QoS mapping selection algorithm based on the sub-level and priority of QoS service is used in the two-way QoS mapping adjustment mechanism to adaptively select more refined QoS. As an experimental result, the proposed mechanism can greatly improve the utilization of network resource and the user's satisfaction.

Modeling Handover in Satellite Communications

The Handover is one of the key subjects in maintaining the quality of service offered by non-geostationary constellation systems. As the satellite coverage moves according to the satellite motion, the continuity of a call must be maintained from one satellite to another. In case of the Handover fails, the call is dropped, resulting in a quality degradation of service. In this paper, the performance of several channel assignment strategies for a LEO satellite constellation is evaluated. The FCA and DCA methods are considered where its advantages and disadvantages are highlighted. Moreover, the Handover process implication in the call blocking probability is assessed via simulation. Strategies able to cope with the high number of Handovers, due to the high speed of the satellites, without affecting strongly the capacity of the system are investigated. Simulation models have been developed to implement all the features evaluated in this paper including the mobility model. An analytical description and interpretation of results are also presented.

A new SIR-based sigmoid power control game in cognitive radio networks.

Interference resulting from Cognitive Radios (CRs) is the most important aspect of cognitive radio networks that leads to degradation in Quality of Service (QoS) in both primary and CR systems. Power control is one of the efficient techniques that can be used to reduce interference and satisfy the Signal-to-Interference Ratio (SIR) constraint among CRs. This paper proposes a new distributed power control algorithm based on game theory approach in cognitive radio networks. The proposal focuses on the channel status of cognitive radio users to improve system performance. A new cost function for SIR-based power control via a sigmoid weighting factor is introduced. The existence of Nash Equilibrium and convergence of the algorithm are also proved. The advantage of the proposed algorithm is the possibility to utilize and implement it in a distributed manner. Simulation results show considerable savings on Nash Equilibrium power compared to relevant algorithms while reduction in achieved SIR is insignificant.

RADIO FREQUENCY OPTIMIZATION OF MOBILE NETWORKS IN ABEOKUTA, NIGERIA FOR IMPROVED QUALITY OF SERVICE

Radio Frequency Optimization is an important process in verifying and monitoring the performance of any GSM radio network already deployed in an area. It is a periodic activity that is done to maintain a good radio quality of service and enhance end users’ perception. This research work aimed at improving the Quality of Service (QoS) of the GSM radio network deployed within Abeokuta City, Nigeria in order to retain existing subscribers and attract new ones while continually expanding the network. A drive test was carried out in dedicated mode with the goal of collecting measurement data as a function of location and to identify the eventual black spots in the GSM radio network. The data collected were analysed in post-processing software tool (MapInfo Professional) to identify the causes of problems and determine how these problems can be solved effectively and efficiently. Poor network coverage and degradation in QoS were encountered in some parts of the city. This performance was due to the land topology and the presence of physical obstructions in the propagation environment. The Hand-Over (HO) failures were mainly due to Base Station Controller (BSC) synchronization issue. Therefore, additional Base Stations were planned to be deployed in those areas; and the BSC synchronization issue was resolved. This will resolve frequent network complaints that lead to customers’ dissatisfaction and boost the revenue of the mobile network provider.

Evaluation of Long Term Evolution Cellular Network Performance when Transmitting Multi-view Video Content

The Long Term Evolution (LTE) cellular technology provides higher data rates than its predecessor technologies. This advancement paves the way for more data services, including improved multimedia services. Three-dimensional (3D) video transmission is one such service that can benefit from LTE deployment. For a positive uptake of 3D video transmission, the network must provide a good Quality of Service (QoS). In this paper the authors evaluate the LTE network's performance when transmitting Multi-view Video Coding (MVC) using simulcast and inter-view prediction coding. Furthermore, the authors evaluate the system using both the H.264/AVC (Advanced Video Coding) and the more recent High Efficiency Video Coding (HEVC) and their MVC extensions. Results show that, in an urban environment, LTE can accommodate a maximum of 93 users per cell, with adequate QoS, when transmitting 3D HEVC video at Common Intermediate Format (CIF) resolution. Moreover, cross-layer techniques can be used to reduce the QoS degradation as the user moves away from the eNodeB by transmitting lower resolution video.

The negative impacts of hosting mega-sporting events and intention to travel: a test of the crowding-out effect using the London 2012 Games as an example

This study examines the negative impacts of mega sporting events on host cities and the relationship between negative impacts and the travel intentions of potential international tourists. Data were collected from Shanghai University students, who were asked about their international travel experiences, London Games awareness, the perceived negative impacts of the Games on London and their travel intentions during the London Games. Travel inconvenience was the most negative impact recorded, followed by price inflation, security and crime concern, risk of disease and pollution and environment concern. Respondents were unsure about any negative impact on service quality degradation. Negative impacts did not vary according to age or gender. Travel inconvenience and price inflation were found to be significantly but negatively related to intention to travel.

Real-Time Traffic-Differentiated QoS Routing for Wireless Sensor Networks

Wireless sensor networks (WSNs) emerge as underlying infrastructures for new classes of large scale networked embedded systems. However, WSNs system designers must fulfill the Qualityof-Service (QoS) requirements imposed by the applications (and users). Very harsh and dynamic physical environments and extremely limited 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. This paper proposes a Real-Time Traffic-Differentiated Routing protocol for Wireless Sensor Networks (WSNs). It targets WSN applications having different types of data traffic with several priorities. The protocol achieves to increase packet reception ratio and reduce end-to-end delay while considering multi-queue priority policy, two-hop neighborhood information, link reliability and power efficiency. The protocol is modular and utilizes memory and computational effective methods for estimating the link metrics. Numerical results show that the proposed protocol is a feasible solution to addresses QoS service differentiation for traffic with different priorities.

User Access Control and Authentication System for VoIP Service in Mobile Communication Environments

VoIP, which is used to transmit voice data on the Internet, is being welcomed as a replacement for the PSTN. In VoIP, voice data are converted to IP data and transmitted in an ordinary IP network. As a result, it is less expensive than the ordinary telephone network and has excellent scalability. With the increasing demand for VoIP services, problems are also occurring, namely, security vulnerabilities and degraded service quality. To address these issues, in this paper an AA (Attribute Authority) server is added to VoIP to design an authentication system with bolstered security and differentiated user access.

Supporting seamless mobility for P2P live streaming.

With advent of various mobile devices with powerful networking and computing capabilities, the users' demand to enjoy live video streaming services such as IPTV with mobile devices has been increasing rapidly. However, it is challenging to get over the degradation of service quality due to data loss caused by the handover. Although many handover schemes were proposed at protocol layers below the application layer, they inherently suffer from data loss while the network is being disconnected during the handover. We therefore propose an efficient application-layer handover scheme to support seamless mobility for P2P live streaming. By simulation experiments, we show that the P2P live streaming system with our proposed handover scheme can improve the playback continuity significantly compared to that without our scheme.

Q-CBQ기반 MPLS망에서 Q-MOTP의 멀티미디어 객체 데이터 전송 QoS 지원을 위한 자원 관리자

The internet will should require the QoS(quality of service) guarantees that the real-time traffic like as audio and video data will be operated well in the future. We had designed Q-MOTP which transfer multimedia object data and proved excellent performance. This paper describes an adaptive QoS management architecture and mechanism based on the information of system resources. Resource manager reports the system resource information periodically or when resources are in the overload state, or on demand by the QoS manager. By using this information, the QoS manager can predict QoS degradation and perform CAC.