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Communications Quality and Reliability (CQR), 2011 IEEE International Workshop Technical Committee on

Date 10-12 May 2011

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Displaying Results 1 - 21 of 21
  • Subjective audio quality impairments of playout adaptation with AAC RTP communication

    Publication Year: 2011 , Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (160 KB) |  | HTML iconHTML  

    Adaptive playout is a core component of almost every Internet-based real-time communication system. The main concept of playout adaptation is to schedule the playout time of incoming audio frames using time scaling techniques. The ACE (Audio Communication Engine), a low delay audio communication system performs adaptive playout by exploiting the structure of the underlying AAC codec. To the best of our knowledge, no in-depth study on the impact of these techniques on the audio quality has been accomplished so far. This paper presents the results of comprehensive subjective listening tests, assessing the quality of time stretching and shrinking mechanisms, as used by the ACE. The listening tests have been conducted according to the BS.1534 (MUSHRA) specification and cover different aspects of playout adaptation, for instance implicit re-buffering, frame dropping and combinatory effects. The test results clearly show the high audio quality of ACE's time scaling techniques and point out their limits. In addition, the listening test results can be used as configuration guidelines to optimize the audio quality towards acceptable late loss and adaptation aggressiveness. View full abstract»

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  • SoKey: New security architecture for zero-possibility private information leak in social networking applications

    Publication Year: 2011 , Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (334 KB) |  | HTML iconHTML  

    We propose new security architecture, Socially Keyed (SoKey) architecture, to achieve zero possibility for personal information leak from social network sites (SNS). SoKey makes sure that the private information provided to a social networking server will never leak even in the worst cases, such as when the security administrators involve in information thefts, at the same time it allows flexible access controls to the users who have access permission. The master key server is also introduced, which guarantees no possible leak of the master keys. We designed and conducted a questionnaire to study how much SoKey would contribute to SNS users by mitigating or eliminating their fear for possible information leak. We found that SoKey will contribute to the people who are already using a social networking application. View full abstract»

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  • Effects of fully redundant dispersity routing on VoIP quality

    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (455 KB) |  | HTML iconHTML  

    Quality and reliability problems are characteristic of real-time services on the Internet such as Voice over IP (VoIP). In this paper the availability of diversity in the Internet is investigated to overcome these flaws. Fully redundant dispersity routing exploits diversity by routing complete copies of the data to be communicated along multiple paths. By actively replicating the data along multiple paths, the effect of a failure on one path may be reduced - or even masked completely - by other paths. This paper presents simulations of such a system, drawing on real VoIP traffic data for the loss, latency and jitter characteristics that data may experience while traversing a path. These simulations show that this form of dispersity routing reduces loss and mean loss burst length, has a de-jittering effect through competition among the paths, and that small numbers of paths already yield significant improvements in deliverable VoIP quality - from 84.12% of calls with which users are estimated as being `very satisfied', to 99.86% using fully redundant dispersity routing with just two paths. View full abstract»

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  • Evaluating geographic vulnerabilities in networks

    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (266 KB) |  | HTML iconHTML  

    In wireless ad-hoc and wireline networks used for search and rescue, military operations, and emergency communications; many failure modes are geographic in nature. They include jammers, explosions, enemy attacks, terrain issues, and natural causes like floods, storms, and fires. This paper proposes two methods to gain valuable insights into the physical topography and geographic vulnerabilities of networks. The 2-Terminal method and All-Terminal method find areas that given a threat of a certain radius can disconnect either the source and destination pair or any component of the network respectively. We believe that these methods could be used to optimize network node selection, placement and design. To be tractable, both methods incorporate innovative search techniques to use the size of the threat to reduce the complexity of the search. View full abstract»

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  • Multicast pre-distribution in VoD services

    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (357 KB) |  | HTML iconHTML  

    The number of users of VoD services in which users can request content delivery on demand has increased dramatically. In VoD services, the demand for content changes greatly daily. Because service providers are required to maintain a stable service during peak hours, they need to design the system resources based on the demand at the peak time, so reducing the server load at the peak time is an important issue. Although multicast delivery in which multiple users requesting the same content are supported by one delivery session is effective for suppressing the server load during peak hours, the response time of users seriously increases. A P2P-assisted delivery system in which users download content from other users watching the same content is also effective for reducing the server load. However, the system performance depends on selfish user behavior, and optimizing the usage of system resources is difficult. Moreover, complex operation, i.e., switching the delivery multicast tree or source peers, is necessary to support VCR operation. In this paper, we propose to reduce the server load without increasing user response time by multicasting popular content to all users independently of actual requests as well as providing on-demand unicast delivery. Through numerical evaluation using actual VoD access log data, we clarify the effectiveness of the proposed method. View full abstract»

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  • Bayesian piggyback control for improving real-time communication quality

    Publication Year: 2011 , Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (186 KB) |  | HTML iconHTML  

    The critical tasks in designing a real-time communication system, such as online games, voice chat, and video conference applications, is to keep the end-to-end delay and jitter as low as possible. Delays and jitters are usually caused by network congestion and packet losses. A packet loss event will trigger the timeout retransmission mechanism at the transport layer, however, it is time consuming. Therefore, it is important to detect a loss event and do the retransmission efficiently. To achieve this goal, we propose a Bayesian loss detection mechanism based on the round trip time. We show that our loss detector can achieve high accuracy and high probability of detection as the false alarm ratio is lower than 20%. In addition, we also present a piggyback scheme for packet retransmission. Cooperated with the loss detector, the piggyback scheme can reduce the end-to-end delay and jitter to less than half of that of the original real-time communication system. Moreover, it generates few overheads to the network. View full abstract»

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  • TXOP exchange: A cooperation mechanism for wireless access networks

    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (629 KB) |  | HTML iconHTML  

    We discuss a cooperation framework applicable for wireless access networks, in which wireless users compete for opportunistically available bandwidth with one another to satisfy each quality-of-service (QoS) demand. Our key concept is to encourage a user with low QoS requirement to provide its redundant bandwidth to another user requesting more bandwidth. The provider of bandwidth at this time can be a client at the next moment, and vice versa. Such cooperative exchange of bandwidth increases chances to satisfy QoS requirements. This paper shows how to incorporate our framework in wireless local area networks (WLANs), which is called TXOP (Transmission Opportunity) Exchange. TXOP Exchange enables flexible bandwidth exchange between compliant STAs in WLANs without any effect on the legacy access point and legacy STAs. In this paper, we particularly show how to implement the TXOP providing function in uplink WLANs and demonstrate how it works through simulation results. View full abstract»

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  • QoE assessment in olfactory and haptic media transmission: Influence of inter-stream synchronization error

    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (276 KB) |  | HTML iconHTML  

    In this paper, we deal with harvesting fruit in a 3-D virtual space for an olfactory and haptic media display system. Making use of the system, a user can pick fruit from a tree in the 3-D virtual space and perceive the smell of picked fruit by using an olfactory display (SyP@D2) and the reaction force when picking fruit by using a haptic interface device (PHANToM Omni). In the case where there exists inter-stream synchronization error between olfactory and haptic media, we assess the inter-stream synchronization quality as the quality of experience (QoE). View full abstract»

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  • Route instruction mechanisms with ‘longcut’ paths for mobile users

    Publication Year: 2011 , Page(s): 1 - 5
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (704 KB) |  | HTML iconHTML  

    The recent advent of smartphones and mobile thin-clients has increased opportunities for people to download a large volume of data via wireless access networks while they on the move. In this study, we considered a scenario in which a mobile user moving from one location to another has to arrive at the destination within a certain period of time and wants to obtain as much data as possible before arriving there. In scenario like this, wireless access points on routes that a lot of people pass through become congested. In particular, if the communication range of the wireless access point is limited like wireless local access networks, the wireless bandwidth becomes more competitive. We therefore propose route instruction mechanisms for mobile users that consider `longcut' paths. Our mechanisms direct mobile users to another route on which wireless access points are less competitive. However, we need to consider the tradeoff between the loss caused by the additional movement and the amount of additionally downloaded data. Furthermore, when there are two or more users, this route instruction problem can be modeled as a cooperation problem because the users selfishly try to occupy the best route for themselves. We therefore came up with and compared cooperative and non-cooperative route instruction mechanisms. Computer simulation demonstrated that the former approach brings better fairness for users. View full abstract»

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  • Performance evaluation in trust enhanced decentralised content distribution networks

    Publication Year: 2011 , Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (283 KB) |  | HTML iconHTML  

    Content Delivery Networks (CDN) have become a key architecture in the provision of today's Internet based services like Video on Demand. A higher degree of decentralisation in the implementation of CDNs is the next possible step to ensure quality levels but also to be more Internet Service Provider (ISP) friendly in the operation of CDNs. This paper discusses the impact of trust enhancements into peer-to-peer (P2P) based content distribution protocols using the BitTorrent protocol as an example. View full abstract»

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  • Using IPDR to transfer network management and measurement information

    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (905 KB) |  | HTML iconHTML  

    Due to recent boom of network applications, access to network usage data has earned tremendous attention. As traditional usage exporting mechanisms become inadequate to support current needs, the Internet Protocol Detail Records(IPDR) stands as an outstanding solution in transferring general network management and measurement information. This paper briefly describes IPDR in terms of high-level model and information content. To incarnate the use of IPDR as an exporting mechanism of network usage data, advanced service definitions are subsequently introduced as part of Data Over Cable Service Interface Specification (DOCSIS). It further highlights the comparison between IPDR and Simple Network Management Protocol (SNMP) and explains why IPDR produces better performance. Last but not least, an exporter application is demonstrated as an implementation of IPDR streaming protocol. This application is developed by Active Broadband Networks based on Junos-SDK (Juniper Operating System-Software Development Kit), which can be applied to transferring interface statistics as well as Multiprotocol Label Switching (MPLS) records. View full abstract»

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  • Characteristic analysis of individual call blocking rate and resource utilization by using our mixed delay and loss system

    Publication Year: 2011 , Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (203 KB) |  | HTML iconHTML  

    We have proposed a novel Call Admission Control (CAC) to maximize total user satisfaction in a heterogeneous traffic network by using buffer for broadband flows and showed the effectiveness of our CAC by using optimal-threshold from numerical analysis. However, we have not yet evaluated the individual call blocking rate and resource utilization of performance when we use proposed CAC under various traffic configurations. In this paper, we conducted a characteristic analysis of individual call blockign rate and resource utilization by using the minimum total call-clocking rate when traffic parameters of narrowband and broadband flow change. View full abstract»

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  • Application identification from encrypted traffic based on characteristic changes by encryption

    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (307 KB) |  | HTML iconHTML  

    Application identification is paid much attention by network operators to manage application based traffic control in the Internet. However, encryption is one of the factors to make application identification difficult, because it is so hard to infer the original (unencrypted) packets from encrypted packets. Therefore the accuracy of application identification is getting worse as the increase of encrypted traffic. In this paper, the changes in traffic features due to encryption are analyzed, and two methods are developed that can be used with an existing method for identifying applications from encrypted traffic. Experimental results show that these methods improve identification accuracy up to 28.5% for encrypted traffic compared to existing methods. Moreover, identification using the best combination of flow features enables high accuracy with less computation due to the elimination of features that do not flow a Gaussian distribution and thus degrade accuracy. View full abstract»

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  • Performance evaluation of TCP over multiple paths in fixed robust routing

    Publication Year: 2011 , Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (277 KB) |  | HTML iconHTML  

    Fixed robust routing is a promising approach for ISP networks to accommodate variable traffic patterns with low operational complexity. The routing minimizes the maximum link load by distributing traffic of every source-destination pair to multiple paths (multipath routing). The multipath routing can result in performance degradation of TCP because of frequent out-of-order packet arrivals. In this paper, we first investigate the influences of delay differences among multiple paths and ratio of shorter paths among multiple paths on TCP performance with simulation using ns-2. The simulation results clarify that smaller delay difference and lower ratio of shorter paths among multiple paths lead to higher TCP throughput. Based on the investigation results, we next propose fixed robust routing algorithms that try to improve TCP throughput in addition to decreasing the maximum link load. The first algorithm called MDD (Minimum Delay Difference) selects a set of paths with the minimum delay differences between the shortest and the longest paths as candidate paths for every source-destination pair The second algorithm called MDD-LF (Minimum Delay Difference with Limited Fraction) bounds the fraction of traffic routed on the shortest delay path in addition to selecting the same candidate paths as MDD. Simulations using ns-2 show that, compared to a straightforward fixed robust routing that selects k-shortest hop paths as the candidate paths, MDD and MDD-LF achieve about 22% and 27% higher TCP throughput while MDD and MDD-LF produce about 1.7 and 2.3 times higher maximum link load, respectively. View full abstract»

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  • Video quality in next generation mobile networks — Perception of time-varying transmission

    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (323 KB) |  | HTML iconHTML  

    Next Generation Mobile Networks (NGMNs) provide an all-IP wireless platform for multimedia service delivery. The integrated communication system creates new perspectives for wireless video distribution and quality provisioning. Depending on the mobility patterns of the nomadic users, the link layer characteristics may rapidly change. Furthermore, mobility and service adaptation events like network handovers, video bit rate switching, or codec changeovers, may affect the user perception. Provisioning “always best connected” video services requires a thorough knowledge of video quality perception in NGMNs. In this paper, we address this problem. A subjective test including 50 NGMN conditions has been carried out. They were arranged in groups to assess the impact on perceived quality of 1) the access technology and network handover, 2) video codecs and codec changeover, 3) video bit rate and bit rate switching, and 4) to provide guidelines for packet loss adaptation. We could identify the perceptual bottlenecks of the future wireless communication and are able to propose perceptual guidelines for mobility management. In this way, this paper contributes to the service quality improvement of future wireless communications. View full abstract»

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  • Performance evaluation of path cost improvement in inter-layer 3 networking with ID/Locator separation architecture

    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB) |  | HTML iconHTML  

    ID/Locator separation architecture is proposed in order to reduce routing table size in the current Internet. In this architecture, an end-host can be identified by unique ID which is independent of its network protocol in use. This capability of identifying an end host with ID enables communication with end hosts operating different network-layer protocol. This inter-layer 3 networking brings another benefit of improvement of shortest path because it enables paths including other network(s) and increases candidate paths between host pairs. In this paper, we evaluate this improvement of shortest path brought by inter-layer 3 networking. In inter-layer 3 networking, a shared node connecting different network layer plane plays an important role. We evaluate shortest path improvement with various shared node locations and show that strategic assignment of shared nodes brings large improvement. View full abstract»

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  • A distributed measurement method for reducing measurement conflict frequency in overlay networks

    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (205 KB) |  | HTML iconHTML  

    In overlay networks, in order to obtain accurate measurement results, it is important to solve the measurement conflict problem : the measurement tasks for overlapping paths conflict with each other. In this paper, we propose a measurement method which reduces the number of measurement conflicts, without centralized control in measurement tasks scheduling. In this method, each overlay node uses traceroute to get path information to other overlay nodes and exchanges it with nearby overlay nodes to estimate path overlaps. Based on the number of overlapping paths, the overlay node calculates an appropriate measurement frequency and a measurement timing to minimize the probability of measurement conflicts occurring among overlapping paths. Furthermore, the overlay node exchanges measurement results with a small number of overlay nodes to statistically obtain more accurate measurement results. Simulation results show that when the density of the overlay nodes (the ratio of the number of overlay nodes to the number of routers) is greater than 0.3, our method can run twice as many measurement tasks as existing methods without measurement conflict. View full abstract»

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  • Understanding the performance of thin-client gaming

    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1269 KB) |  | HTML iconHTML  

    The thin-client model is considered a good fit for online gaming. As modern games normally require tremendous computing and rendering power at the game client, deploying games with such models can transfer the burden of hardware upgrades from players to game operators. As a result, there are a variety of solutions proposed for thin-client gaming today. However, little is known about the performance of such thin-client systems in different scenarios, and there is no systematic means yet to conduct such analysis. In this paper, we propose a methodology for quantifying the performance of thin-clients on gaming, even for thin-clients which are close-sourced. Taking a classic game, Ms. Pac-Man, and three popular thin-clients, LogMeIn, TeamViewer, and UltraVNC, as examples, we perform a demonstration study and determine that 1) display frame rate and frame distortion are both critical to gaming; and 2) different thin-client implementations may have very different levels of robustness against network impairments. Generally, LogMeIn performs best when network conditions are reasonably good, while TeamViewer and UltraVNC are the better choices under certain network conditions. View full abstract»

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  • On the battle between lag and online gamers

    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (522 KB) |  | HTML iconHTML  

    Although online games have been an important Internet activity today, players inevitably suffer from lag from time to time due to the Internet's non-QoS-guaranteed architecture. Here by lag we refer to the phenomena when a game fails to respond to user commands or update the screen in a timely fashion due to long system processing or network delays. Currently, little is known about how game players feel about lag and how they react when encountering lag during game play. In this paper, we present an Internet survey that is designed to understand the following questions: 1) How do players perceive lag, 2) what do players think of the causes of lag, and 3) how do players react to lag. Our results show that game players often struggle with lag, because they are unable to identify the root cause. Therefore, they have to try any combination of possible solutions found on the Internet, blame game companies, or learn to cope. These findings manifest a strong demand for an automatic diagnostic tool that can identify the root cause of lag for gamers. View full abstract»

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  • Characteristics of QoS-guaranteed TCP on real mobile terminal in wireless LAN

    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (454 KB) |  | HTML iconHTML  

    For multimedia communications such as video streaming, a QoS-guaranteed TCP (QoS-TCP) has been proposed and evaluated in characteristics of guarantee performance. For wired networks QoS-TCP can guarantee a target bandwidth against competitive back ground TCP traffic, depending on number of the competitive TCP flows and the target bandwidth. In this paper, the characteristics of QoS-TCP in mobile and fixed wireless networks are investigated through both computer simulations and real terminal experiments in both outdoor and indoor environments. Many wireless related factors such as radio interference and handover could affect the performance as well as buffer size and queueing behavior of access points. The experiment results show that QoS-TCP has a possibility to guarantee a target bandwidth, with depending on both the specified target bandwidth and mobile wireless environments (channel capacity). View full abstract»

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  • Efficient content sharing taking account of updating replicas in hybrid peer-to-peer networks

    Publication Year: 2011 , Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (612 KB) |  | HTML iconHTML  

    Recently, peer-to-peer (P2P) traffic of contents sharing among network users has become one of the major parts of the Internet traffic, and many kinds of contents replication techniques have been investigated for smooth contents retrieval according to the users' requests. However, the strategies are almost for pure P2P networks and those for hybrid P2P have not thoroughly researched yet. In a hybrid P2P system, it is relatively important to restrain storage resources, because the network load for contents searching is small. And besides, when a content item the replicas of which are scattered on a number of peers is updated, it is necessary to maintain their consistency. This paper proposes a method of content replication that restrains the consumption of the storage resources, and at the same time, manages contents' consistency corresponding to their update for contents sharing in hybrid P2P networks. Furthermore, the effectiveness of the proposal is evaluated using computer simulations. View full abstract»

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