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We consider the realtime services over on-demand routing protocols in ad hoc networks, where infrastructure does not exist and the network topology is highly dynamic and time-varying due to node mobilities. To reduce the end-to-end delay, we have proposed two efficient routing protocols: MSR (Multipath Source Routing) and RSR (Redundant Source Routing) in our previous work. Simulations have shown...
In this paper we investigate a model for delay-optimal scheduling for networks using relay station (RS) in contemporary broadband wireless access networks. We present an optimal control problem using a queueing model based on Markov Decision Process (MDP) incorporating an opportunistic scheduling for downlink in a RS architecture. Using a simplified queueing model for access networks, we propose a...
Cross-layer algorithms that jointly allocate resources at different layers are known to foster the communication performance in wireless networks. Recent works have shown that fading and queue information are among the most critical parameters to consider in cross-layer designs. Motivated by those findings, this work develops optimal algorithms that use instantaneous fading and queue length information...
The IETF Differentiated Service (DiffServ) architecture can allow for establishing a modern large scale network which guarantees the quality of service. In order to realize the multiple levels of packet drop precedence required for the Assured Forwarding (AF) framework of DiffServ, a multi-level RED algorithm is needed. RIO (RED with In/Out) is suitable for the AF scheme, and two major RIO variants...
Backfilling is well known in parallel job scheduling to increase system utilization and user satisfaction over traditional non-backfilling scheduling algorithms, which allow small jobs from the back of the queue to execute before larger jobs arriving earlier, and resources could be reserved to protect the latter from starvation. This paper proposed a relaxed backfill scheduling mechanism supporting...
Scheduling has a great influence in improving computer system performance. Many recent system designs use policies which give priority to short jobs as it is often the case that the majority of the jobs are short. SRPT (Shortest Remaining Processing Time First), which servers the jobs that needs the least amount of service to complete, is known to produce optimum mean response time. However SRPT requires...
In this paper we discuss the viability of utility-based abstractions for network management. These can be used for estimation and optimization of the network performance. We consider utilities that are determined by the application type, but also take into account changing user and provider context. These metrics incorporate technical performance characteristics, economic and personal considerations...
DOCSIS is a de facto standard for data transmissions on CATV/HFC networks. In DOCSIS, an upstream channel is shared by many stations, and the stations send out their data PDUs according to the random reservation manner. Before data transmission, the station must send a request in a random access manner during the reservation period called a request cluster. Recently, DOCSIS has introduced a concept...
Exact queueing analysis of erasure networks with network coding in a finite buffer regime is an extremely hard problem due to the large number of states in the network. In such networks, packets are lost due to either link erasures or due to blocking due to full buffers. In this paper, a block-by-block random linear network coding scheme with feedback on the links is selected for reliability and more...
The popularity of web based social networks is rapidly increasing nowadays. These solutions allow managing relationships online. There are also several mobile solutions to these networks but they are mainly limited to reaching the services of the social network from the mobile device. The fact, that the phonebook of the mobile phones also represents social relationships, can be used for detecting...
Load balancing in wireless mesh networks (WMNs) is one of the major design goals for any routing protocol. In this paper, we propose AntMesh, an efficient data forwarding scheme, specifically designed for load balancing in multi-radio infrastructure WMNs. As the foundation of AntMesh, we use Ant Colony Optimization (ACO) in which artificial ants (agents) perform the routing and data forwarding to...
Sequential interview is a common method for intellectual selection. In this study we formulate a sequential selection problem. In a setting where a choice sequence among candidates is established for filling a job position, the analysis explicitly takes into account the benefits from the hiring, the risk of rejection of the job offer, and the costs due to delay in filling the position. The most important...
We propose a simple unified analytical model to analyze the IEEE 802.11 DCF infrastructure BSS performance in terms of MAC delay, PLR, and throughput efficiency under non-homogeneous and non-saturation conditions. Our model accounts for: (i) asymmetric traffic load between an AP and its associated STAs of an infrastructure BSS; (ii) transition from the non-saturation to saturation mode (and vice-versa)...
Random Early Detection (RED) algorithm, a framework of active queue management (AQM), has been proposed in order to improve the performance of congestion routers due to the increased use of Internet. But, the basic problem of a lag between congestion's occurrence and its remedy remained. To overcome this problem of RED, Explicit Congestion Notification (ECN) proposed by the IETF that allows end-to-end...
Active Queue Management (AQM) plays a very important role in congestion control of Transmission Control Protocol/Internet Protocol (TCP/IP) networks. This paper attempts to design an improved proportional-integral-proportional-derivative (PI-PD) controller as an active queue manager for TCP routers. The proposed controller scheme controls present congestion reactively and also avoids the incipient...
Active queue management (AQM) mechanism plays an important role in network congestion control. In this paper, we propose an effective AQM algorithm, named adaptive real queue control (ARQC). In particular, an explicit congestion indicator, virtual regulating time, is designed to detect network congestion. Then by analyzing the queuing system on routers, we present the guideline to calculate the dropping/marking...
One of the most critical problems in multihop wireless networks is the fair allocation of bandwidth among different nodes. Although there are significant researches on the fairness issues in single-hop wireless networks, research on multihop fairness rarely found in the literature. A user in multi-hop network, besides the contention with other nodes to obtain the channel in physical layer, must find...
This paper presents a queueing model that provides a performance upper-bound for Multi-rate Downlink SDMA systems. It is shown that the performance of Downlink SDMA systems depends to a great extent of parameters such as the number of active users, the traffic arrival process, the queue size, the number of antennas and the set of available transmission rates. Using this upper-bound as a reference,...
This paper presents a mixed analytical model of preemptive streaming and elastic traffics with binary dynamic channel allocation scheme, similar applied in CDMA. Also there is a finite buffer to temporarily store the non preempted data calls. Different classes of traffic have different quality of service (QoS) requirements. Formulae for performance characteristics e.g. blocking probabilities and mean...
Task scheduling problems are of paramount importance which relate to the efficiency of the whole cloud computing facilities. In Hadoop, the open-source implementation of MapReduce, scheduling policies, such as FIFO or delay scheduling in FAIR scheduler is used by the master node to distribute waiting tasks to computing nodes (slaves) in response to the status messages of these nodes it receives. Although...
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