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The following topics were dealt with: IEEE 802.11b/g networks; wirless LANs; H.264 video streaming; QoS; IPTV service; SLA assessment; Internet mobility; mobile 3G network; dynamic bandwidth allocation; G-PON systems; congestion control; MAC protocol; distributed storage; IP flow networks.
Over the years, IEEE 802.11b/g wireless networks have been deployed in various locations such as hotels, airports and enterprises. Although IEEE 802.11b/g can be considered a mature technology, its deployment still presents challenges due to the limited number of non-overlapping channels available. This is particularly true in scenarios with a high density of users where a large number of APs covering...
We present extensions to the IEEE 802.11 WLAN architecture to facilitate the deployment and operation of large-scale networks. A new distribution system (DS) is designed to work across IP networks removing the need for an Ethernet backbone. APs connected to different IP networks can join the DS to form a single WLAN, with link-layer mobility support for users. Two entities, portal and registry, are...
Recent years have seen a growing demand for high quality multimedia traffic over wireless links. Due to the strong demands imposed to all the involved actors, several optimization techniques have been proposed and studied, mostly through theoretical analysis and simulation. In this article we focus on the practical evaluation of H.264 video streaming performance over IEEE 802.11e wireless devices...
Wireless technologies have rapidly evolved and are becoming ubiquitous. An increasing number of users attach to the Internet using these technologies; hence the performance of these wireless access links is a key point when considering the performance of the whole Internet. In this paper we present a measurement-based analysis of the performance of an IEEE 802.16 (WiMAX) client and an UMTS client...
Due to the unreliable nature of the wireless medium, provisioning of quality of service (QoS) in wireless LANs is far more complicated than in wired networks. In order to address this challenge, IEEE 802.11e defines a framework for QoS support where packets are prioritized based on their traffic characteristics. In this paper, we propose two new QoS support schemes. One is based on a ldquouser centricrdquo...
Despite the fact that the Request-To-Send/Clear-To-Send (RTS/CTS) protocol significantly reduces collisions and retransmissions due to the hidden node problem, it is well known that it adds considerable overhead specially with small payload packets. The IEEE 802.11 standard defined a manageable parameter, RTS threshold, above which a data packet should be preceded with RTS/CTS handshake. In this paper,...
IEEE 802.11 k is an extension of the IEEE 802.11 specification for radio resource measurements. In an IEEE 802.11 k-enabled wireless LAN, an access point or other network element may request from a client or another access point to monitor and report the load of a channel. We call the latter a channel monitoring station. In this paper we propose a mechanism for a channel monitoring station to efficiently...
Disaster recovery and business continuity issues are becoming fundamental in networks since the importance and social value of digital data is continuously increasing. On the one hand, there is an obvious need of backing up data for resilience against major failures; in many situations the process of storing backup data is also enforced by the law. On the other hand, providing services that allow...
Broadcast TV distribution over an IP network requires stringent QoS constraints, such as low latency and loss. The main challenge to achieving these QoS objectives is how to design the network to respond to network failures. Streaming content in IPTV is typically delivered to the distribution points on the IP backbone using IP multicast, and in the case being considered, with protocol independent...
New business infrastructures over the Internet pose a new set of traffic constraints. In particular, multimedia and interactive contents require guarantees of bandwidth and delivery time. The broad deployment and real-time nature of this class of applications require the provisioning of specific resources in the network to guarantee a certain level of quality of service (QoS). QoS techniques need...
Network traces are a valuable source of information for modeling and analysis of network behavior and for the evaluation of network protocols. These crucial activities should be supported with reliable traffic traces. Reliable packet capturing facilities should be devoted to avoid losing packets and at the very last, report when packets have been lost with the highest accuracy possible. This paper...
Mobility is a requirement not appropriately addressed by the original design of the Internet since an IP address has two fundamentally different tasks. It specifies a network location (for routing) and serves as an application identifier. A plethora of suggestions have been made to overcome this, e.g., Mobile IP and HIP. Yet, each of the proposed solutions has drawbacks such as requiring fundamental...
In this paper we investigate the dynamics of one-way delays in an operational mobile core network. Our final goal is to develop anomaly detection schemes for the packet delay process in order to reveal network and equipment problems. This requires a preliminary exploration of the delay distribution in the core network, which we undertake in this study. We present one-way delay measurements extracted...
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