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Point to multipoint multicast (MC) packets delivery without optimal distribution trees is prone to unnecessary retransmissions that adversely influences narrow-band VHF networks. The bandwidth efficient MC packet delivery path has to be calculated to best reach all destinations using the inherent broadcast nature of VHF radio subnets by avoiding retransmissions of the same message/packet in the same...
Wired-cum-wireless networks are interconnected through proxy or gateway that acts as router and also caters for link MTU mismatch between the two networks. In IPv6 based networks, TCP is mandatory for bulk data transfer from wired to wireless host. This results in end-to-end TCP session through the default proxy. The single proxy supporting a large number of TCP sessions; is vulnerable to buffer overflow...
Recently, Variable-structure Congestion-control Protocol (VCP) has emerged as a great practical alternative of deployment for congestion control by requiring the use of only two ECN bits in the IP header. However, VCP suffers from a relatively low speed of convergence and exhibits biased fairness in moderate bandwidth high delay networks due to utilizing an insufficient amount of congestion feedback...
When supporting both voice and TCP in a wireless multihop network, there are two conflicting goals: to protect the VoIP traffic, and to completely utilize the remaining capacity for TCP. We investigate the interaction between these two popular categories of traffic and find that conventional solution approaches, such as enhanced TCP variants, priority queues, bandwidth limitation, and traffic shaping...
Active Queue Management (AQM) algorithm is important to manage buffers and transfer packets for wired/wireless networks. However, the unresponsive flows to the network congestion control is dangerous to the network equilibrium and Quality of Service (QoS), especially from the point of network resource allocation. In some certain scenarios, the limited network resource (buffers) can be occupied by...
When supporting both voice and TCP in a wireless multihop network, there are two conflicting goals: to protect the VoIP traffic and to completely utilize the remaining capacity for TCP. We investigate the interaction between these two popular categories of traffic and find that many solution approaches, such as enhanced TCP variants, priority queues, bandwidth limitation, and traffic shaping, do not...
Wireless Mesh Networks (WMNs) have been expected to be future commercial service-grade networks. OAM (Operations, Administration, and Maintenance) in wired networks is an important tool to guarantee a reliable network performance, WMNs needs such a tool to meet the service providers requirements, and to handle mobility problem. We propose a fundamental architecture of wireless mesh network OAM to...
In this paper, we present a centralized quasi-static channel assignment for multi-radio WMNs (wireless mesh networks) to provide high-throughput paths. We probe data packets at each wireless access point and estimate the traffic load for each network link using a new load estimation algorithm. So the channel assignment can intelligently assigns channels with the objective of maximizing the aggregate...
In this paper, we address the routing and call scheduling problem in which one has to find a minimum-length schedule of selected links in a TDMA (time division multiple access) based wireless network. As we deal with multi-hop networks, these selected links represent a routing solution (paths) providing enough capacity to achieve the routers requirements of bandwidth. We present a cross-layer formulation...
In wireless mesh networks (WMNs), the achievable throughput of a mesh client to a gateway (GW) is limited by the minimum link capacity of the intermediate nodes. In instances when the intermediate nodes experience congestion due to large relay traffic, link failure etc., this throughput may drop below an acceptable level. Since the mesh topology implies multi-path routing capability, it is possible...
In wireless mesh networks, the end-to-end throughput of a flow over a multiple-hop wireless link rapidly decreases as the hop-count between the source and destination nodes increases, and the flows that travel over a path of more than 4-5 hops from its source node eventually starve. To alleviate this unfairness, we propose a weighted random early detection (RED) mechanism that has a different dropping...
Current Internet use is evolving, users are becoming mobile and are expecting data services on the go. This fact presents big challenges and opportunities to operators, which see the increase in data services as a big market still to be exploited. However, current cellular technologies cannot accommodate the demand that will arise when the true mobile Internet evolves. Addressing these challenges,...
The usage of multimedia applications such as IP-TV and Video On Demand over wireless networks becomes more and more popular. In many cases the bandwidth of the wireless channel is the system bottleneck and thus it is important to increase the ability of wireless networks to provide a scalable service for multiple users simultaneously. The main idea proposed in this paper is based on a dynamic bandwidth...
Providing strong QoS guarantees for wireless multi-hop networks is very challenging, due to many factors such as use of a shared communication medium, variability in wireless link quality, and so on. However, wireless mesh technology gives the opportunity to alleviate some of these problems, due to lack of mobility in the wireless infrastructure, and presence of natural centralization points in the...
IEEE P1900.4 is an emerging standard for optimized radio resource utilization where cognitive radio technologies are used for efficient spectrum utilization. In this paper, we design and implement a cognitive wireless network system based on open documents of IEEE P1900.4, and evaluate its performance using UDP streaming and HTTP download. Our experiments show interesting results that total network...
This paper presents a DVB-RCS satellite emulation system built using the NPBox programmable network emulation system. NPBox allows system components to be modeled both at a higher abstraction level using a finite-state-machine like abstraction, and also at a lower level using customized event guards and actions. Comparison experiments show that the emulated performance is similar to that of a complex...
Wireless mesh networking technology has gained prominence in recent years with a diverse range of applications from small community-based networks to metropolitan area networks. Such mesh networks typically comprise a wireless backbone connected to the wired infrastructure with wireless client residing at the edge. The wireless routers and access points of a wireless mesh network (WMN) are connected...
Survivability of wireless mesh networks (WMNs) is a crucial issue that has not received enough attention in the literature. In this paper, we present a network coding-based protection scheme that overcomes the deficiencies in traditional proactive and reactive protection mechanisms. Proactive schemes ((1+1) protection) provide instantaneous recovery, but are resource-hungry. While reactive schemes...
A scheme that exploits the broadcast nature of the wireless communication in order to achieve multicast content delivery is presented in this paper. As opposed to broadcasting, this method enables the clients to determine on-line the delivered content, and thus preserves the advantages of an individual service. On the other hand, a multicast content delivery is much more efficient than a unicast content...
A high intercept points, cost-effective, and power-efficient switching FET double balanced mixer (DBM) is reported. The Switching FET DBM demonstrated in this work offers input intercept points (IIP3) and conversion loss typically 44 dBm and 8.5 dB respectively with 15 dBm LO power for the frequency band (RF: 900-2150 MHz, LO: 850-1950 MHz, IF: 50-200 MHz). The measured interport isolation is typically...
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