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Scheduling schemes of wireless networks determine packet transmission opportunities for each network node by considering network parameters such as link quality, transmission rate, and delay. However, security has not been taken into account in these schemes, although it plays a critical role in network performance. In this paper a new scheduling scheme is proposed to determine packet transmissions...
In the paper, we consider the end-to-end routing and link scheduling problem for multi-hop wireless sensor networks. The efficient link scheduler under our consideration is intended to assign time slots to different users so as to minimize channel usage subject to constraints on data rate, delay bound, and delay bound violation probability. We also present a coupled robust multi-path routing structure...
The emerging WiMAX technology (IEEE 802.16) is a fourth generation standard for low-cost, high-speed and long range wireless communications for a large variety of civilian and military applications. IEEE 802.16j has introduced the concept of mesh network model and a special type of node called Relay Station (RS) for traffic relay for Subscriber Stations (SSs). A WiMAX mesh network is able to provide...
In most existing handshake-based collision avoidance protocols, nodes in the proximity of the transmitter or receiver are kept silent during an ongoing communication session. In this paper, we utilize the long propagation delay in the underwater acoustic channel and the (possible) sparsity of the network topology to increase network throughput. We formalize conditions for which a node can transmit...
Several underwater network characteristics, including long propagation delays and a bandwidth dependent on distance, provide unique challenges to protocol designers. In this paper we present STUMP-WR, a distributed routing and channel scheduling protocol, designed for heavily loaded underwater networks. STUMP-WR selects and schedules links using a distributed algorithm to overlap communications by...
This paper describes CoZi, a new packet scheduling mechanism for large scale ZigBee networks. CoZi aims at enhancing the reliability of the data delivery and the bandwidth utilization of the network. Based on simple network coding, instead of the classic packet forwarding, our algorithm takes advantage of the shared nature of the wireless medium as well as the cluster-tree topology of IEEE 802.15...
Successive interference cancellation (SIC) is an effective way of multipacket reception to combat interference. We study link scheduling under SINR (Signal to Interference Noise Ratio) model in ad hoc networks with SIC at physical layer. The facts that interference is accumulated and the links decoded sequentially by SIC are correlated pose key technical challenges. We propose conflict set graph (CSG)...
In this paper, we study the problem of transmission power control and its effects on the link-scheduling performance when a set of end-to-end flows established in the network are given. This problem is approached by means of the stability region of the link-scheduling policy. The stability region is defined for link-scheduling policies as the set of input-packet rates under which the queues in the...
This paper addresses the question of throughput guarantees through distributed scheduling in wireless sensor networks (WSNs) with relay based cooperative communications. We prove that in a single frequency network with bidirectional, equal power communication, low complexity distributed maximal scheduling attains a guaranteed fraction of the maximum throughput region in arbitrary wireless networks...
In this paper, we mainly focus on how to provide an efficient VoD service via the consideration on the scheduling scheme. Comparing with P2P live streaming, P2P VoD is more challenging due to users are allowed to join or leave the system at any time and watch any part of the video after a small buffering time. If not handled properly, either high work load is caused on the media server side or the...
The IEEE 802.16 mesh network is a promising next generation wireless backbone network. Under Coordinated Distributed Scheduling (CDS) mode, setting the holdoff time for nodes is essential to achieving good performances of medium access control layer scheduling in the networks. In this paper, we propose a dynamic scheme for setting holdoff time in IEEE 802.16 mesh mode with CDS. This scheme allows...
In wireless mesh networks with frequency-agile radios, an algorithm of dynamically combining consecutive channels has recently been proposed. However, the available channel widths are limited in the algorithm. In order to further improve the fairness or the throughput under given fairness, we propose a joint variable width spectrum allocation and link scheduling optimization algorithm. Our algorithm...
The Airborne Internet is envisioned to be a large scale multihop wireless mesh network of commercial passenger aircraft connected via long range highly directional air-to-air radio links. We propose a localized geographic load sharing technique to mitigate congestion in this network, taking into account the underlying link scheduling constraints with directional antennas. When forwarding packets for...
Transmission scheduling is a key design problem in wireless multi-hop networks. Many transmission scheduling algorithms have been proposed to maximize the spatial reuse and minimize the time division multiple access (TDMA) frame length. Most of the scheduling algorithms are topology-dependent. They are generally graph-based and depend on the exact network topology information. Thus, they cannot adapt...
In this paper we propose a mixed bias approach which makes use of cross layer optimization. The cross-layer parameters are based on conditions in the network from multiple layers and are used to determine resource and time allocation for nodes in the network. Unlike existing proposals, we propose to bias against several parameters such as link quality and queue size in addition to node distance. We...
WiMAX (IEEE 802.16) has emerged as a promising radio access technology for providing high speed broadband connectivity to subscribers over large geographic regions. New enhancements allow deployments of relay stations (RSs) that can extend the coverage of the base station (BS), increase cell capacity, or both. In this paper, we focus on deploying RSs for the purpose of coverage extension. We propose...
This paper describes an implementation of a realtime multi-user multiple-input multiple-output (MU-MIMO) communication system, with cross-layer channel-aware scheduling. The system is implemented using software reconfigurable nodes that may be configured as either user terminals, or as base stations, communicating in the GSM 1800 uplink band. Three different commonly used scheduling algorithms (based...
The recent advent of multi-core computing environments increases both the heterogeneity and complexity of managing desktop grid resources, making efficient load balancing challenging even for a centralized manager. Even with good initial job assignments, dynamic scheduling is still needed to adapt to dynamic environments, as well as for applications whose running times are not known a priori. In this...
We consider the problem of broadcasting a large message in a large scale distributed platform. The message must be sent from a source node, with the help of the receiving peers which may forward the message to other peers. In this context, we are interested in maximizing the throughput (i.e. the maximum streaming rate, once steady state has been reached). The platform model does not assume that the...
Efficient operation of wireless networks and switches requires using simple (and in some cases distributed) scheduling algorithms. In general, simple greedy algorithms (known as Greedy Maximal Scheduling - GMS) are guaranteed to achieve only a fraction of the maximum possible throughput (e.g., 50% throughput in switches). However, it was recently shown that in networks in which the Local Pooling conditions...
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