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We consider a wireless Device-to-Device (D2D) caching network, where users make arbitrary requests from a library of files and have pre-fetched (cached) information on their devices, subject to a per-node storage capacity constraint. The network is assumed to obey the “protocol model”, widely considered in the wireless network literature. Unlike other related works, which either restrict the communication...
We present Timestamp Order Preserving (TOP), a replicated state machine (RSM) protocol that exploits the synchrony of networks to provide high performance. TOP uses physical timestamp of synchronized clock as a consistent total order to achieve consensus. It keeps estimating the bounds of network latency and offset of synchronized clock to deduce the commit time for each operation. It adopts speculative...
The various flows in production datacenters usually can be classified into two types: bandwidth-hungry and delay-sensitive. To improve their performance, datacenter networks require effective load balancing and flow control protocols, respectively. However, as the two techniques are typically employed separately in current datacenters, they are unable to optimize the network in a coordinated way....
Distributed applications deployed in multi-datacenter environments need to deal with network connections of varying quality, including high bandwidth and low latency within a datacenter and, more recently, high bandwidth and high latency between datacentres. In principle, for a given network connection, each message should be sent over the best available network protocol, but existing middlewares...
State machine replication is a fundamental approach to high availability. Despite the vast literature on the topic, relatively few studies have considered the issues involved in recovering faulty replicas. Recovering a replica requires (a) retrieving and installing an up-to-date replica checkpoint, and (b) restoring and re-executing the log of commands not reflected in the checkpoint. Parallel techniques...
Big data has, in recent years, revolutionised an evergrowing number of fields, from machine learning to climate science to genomics. The current state-of-the-art for storing large datasets is either object stores or distributed filesystems, with Hadoop being the dominant open-source platform for managing ‘Big Data’. Existing large-scale storage platforms, however, lack support for the efficient sharing...
Recently there has been increased research interest in developing adaptive control systems for autonomous vehicles. This study presents a comparative evaluation of two distinct approaches to automated intersection management for a multi-agent system of autonomous vehicles. The first is a centralized heuristic control approach using an extension of the Autonomous Intersection Management (AIM) system...
With the increasing number of connected devices, new challenges are being raised in the networking field. Software Defined Networking (SDN) enables a greater degree of dynamism and simplification for the deployment of future 5G networks. In such networks, the controller plays a major role by being able to manage forwarding entities, such as switches, through the application of flow-based rules via...
Cross-technology communication (CTC) techniques are introduced in recent literatures to explore the opportunities of collaboration between heterogeneous wireless technologies, such as WiFi and ZigBee. Their applications include context-aware services and global channel coordination. However, state-of-the-art CTC schemes either suffer from channel inefficiency, low throughput, or disruption to existing...
In the non-time-slotted cognitive radio networks (CRNs), the synchronization between PUs and secondary users (SUs) cannot be guaranteed, resulting in two challenging problems: the reactivation-failure of PUs and the frequently unexpected hand-offs among SUs. The reactivation-failure of PUs is the incident that the SUs cannot detect the PUs' reactivation when the SUs are occupying the channels to transmit...
MmWave communications, one of the cornerstones of future 5G mobile networks, are characterized at the same time by a potential multi-gigabit capacity and by a very dynamic channel, sensitive to blockage, wide fluctuations in the received signal quality, and possibly also sudden link disruption. While the performance of physical and MAC layer schemes that address these issues has been thoroughly investigated...
Tor hidden services make it possible to hide Internet services' location. Via so-called rendezvous circuits, Tor users can communicate with hidden services without learning each other's location. In this paper, we propose a performance-enhanced rendezvous circuit, which consists of five instead of six relays. We show that omitting the client's middle relay in a rendezvous circuit brings significant...
This paper represents the design, feasibility evaluation and performance validation of ICMR, a novel cross layer protocol that can maximize concurrent transmissions and avoid data frame interference in wireless networks, achieving higher throughput comparing with the 802.11 standard and other state-of-the-art protocols. Observations on the 802.11 standard reveal that nodes degrade the network throughput...
In this paper, a cross-layer-based sensor node selection scheme in a cooperative network with equally spatially correlated channels is proposed. The equally correlated model can be used as a worst-case benchmark or as a rough approximation by assuming equal correlation coefficients for all channels. By considering the physical and link layer characteristics, one or multiple sensor nodes are selected...
With emerging technology and support for 4G and 5G network, considering Internet and Intranet, the bandwidth is not a big of a problem as it was before. The main concern now is the implementation of security and how efficiently we can send the data to recipients. We have come up with an awesome concept that takes confidentiality and availability as mainstream. The idea in simple words is like our...
In this paper, an analytical model is developed to study the performance of distributed and opportunistic multichannel bonding in IEEE 802.11ac WLANs, with co-existing legacy IEEE 802.11a/b/g users. By modeling the transmissions of legacy users and ac users with and without channel bonding in each channel as a two-level renewal process, the channel bonding probability of ac users in each secondary...
This paper studies the throughput performance of a two-way energy harvesting relaying system. Network Coding and Energy Harvesting are promising techniques that can improve the transmission efficiency and the energy efficiency of wireless systems, respectively. In particular, we focus on the energy harvesting system with the power splitting-based relaying (PSR) protocol, and consider both the amplify-and-forward...
Hybrid beamforming (BF) is a widely considered strategy to enable downlink multiuser transmission for mmWave communication systems. However, current mmWave WiFi standard, the IEEE 802.11 ad, does not support hybrid BF because it could only serve one user at a time. Thus, it is important to implement hybrid BF based on IEEE 802.11.ad such that it could be applied in future mmWave WiFi. In this paper,...
In this paper, we investigate the throughput analysis for the MIMOMAX protocol, a cross-layer design based on multiple transmit and receive antennas (MIMO) capabilities. We propose an analytical model based on a three-dimensional Markov chain. This model includes two additional parameters than the conventional model: a) non-saturated traffic situation, and b) beam strength at the receiver. Each beam...
This paper examines the throughput and power tradeoffs of WiFi communication in smartphones. The energy consumption of three devices with different operating system version and different screen size and resolution was measured in various operating modes. At the same time, the throughput was measured while using different communication protocols. The experiments reveal interesting tradeoffs and show...
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