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A heavy deployment of IEEE 802.11 Wireless LANs and limited number of orthogonal channels make lots of Access Points (APs) overlap their interference regions, which greatly increases interferences between APs and stations. In order to cope with the performance degradation caused by the interferences, we propose Co-Fi, a centralized Wi-Fi architecture that effectively coordinates downlink transmissions...
In this paper we treat the problem of identification of a subset of active users in a set of a large number of potentially active users. The users from the subset are activated randomly, such that the access point (AP) does not know the subset or its size a priori. The active users are contending to report their activity to the AP over a multiple access channel. We devise a contention algorithm that...
A prime source of collisions in underwater acoustic communication networks (UWANs) is the so called near-far effect, where a node located farther from the receiver is jammed by a closer node. While common practice considers such situation as a challenge, in this paper we consider it as a resource, and use it to increase network throughput of spatial reuse time-division multiple access. We propose...
The aim of topology-transparent scheduling algorithms for multi-hop wireless networks is to find a schedule for the nodes that does not need re-computation when the network topology changes. It caters to highly dynamic scenarios where topology changes occur faster than the speed at which schedule updates can be orchestrated. These algorithms normally take as input only global network parameters like...
In IEEE 802.11 based wireless local area networks (WLANs), channel induced errors and collisions cause transmission failures which waste bandwidth and energy. To improve the energy efficiency of battery powered mobile devices we propose a scheme which mitigates channel induced errors and collisions by using two ideas namely, backoff-free fragment retransmission and collision-free transmission schedules,...
It is challenging to schedule multiple dataflow applications concurrently on multi-processor embedded systems with processor sharing. As a viable solution, an approach has been proposed recently, in which the dataflow graphs are transformed into a set of independent realtime tasks. However, it may produce poor resource utilization and excessive buffer usage. Alternatively, we propose a novel two-phase...
The Synchronous Dataflow Graph (SDFG) and Cyclo-Static Dataflow Graph (CSDFG) are two well-known models, used practically by industry for many years, and for which there is a large number of analysis techniques. Yet, basic problems such as the throughput computation or the liveness evaluation are not well solved, and their complexity is still unknown. In this paper, we propose K-Iter, an iterative...
The widespread use of network access technology has enabled the mobile terminals to have multiple interfaces, which promotes the development of multipath transport. However, there exist some important issues on multipath transport, such as out-of-order packets problem which results from the different performance among sub-flows. Those will lead to unnecessary retransmission, even a decrease in throughput...
A multi-mode QC-LDPC decoder is proposed to satisfy the 802.11n/ac WiFi standard. With code-specific design, the overall performance of the decoder is enhanced while ensuring an on-the-fly reconfigurable ability. The proposed architecture has been synthesized using an FPGA for measurements. A state-of-art error rate and implementation complexity are reported. Meanwhile, the throughput has been increased...
Recently, the full duplex communication has been spotlighted as one of key technologies of the future wireless local area network (WLAN). The full duplex MAC protocols are actively researched because the feasibility of full duplexing is achieved because of the technology evolution. The full duplex MAC protocols can be categorized as two types. One is centralized type and the other is distributed type...
Data volume grows dramatically in the era of big data. To save capital cost on storage hardware, datacenters currently prefer using erasure coding rather than simply replication to resist data loss. Erasure coding can provide equivalent three-way fault tolerance to HDFS's default three replication mechanism but degrades data availability for task scheduling. In an erasure-coded system, data reconstruction...
Real-time navigation of autonomous vehicles requires the processing of a large amount of sensor data by the perception algorithms onboard the vehicle, like object detection and localization. To meet the driving performance and safety requirements, these algorithms require the hardware to be over-engineered to always operate for the worst-case. This leads to excessive power consumption by the computation...
Multiprocessor systems are becoming ubiquitous in today's embedded systems design. In this paper, we address the problem of mapping an application represented by a Homogeneous Synchronous Dataflow (HSDF) graph onto a real-time multiprocessor platform with the objective of maximizing total throughput. We propose that the optimal solution to the problem is composed of three components: actor-to-processor...
The FSM-based scenario-aware data ow (FSM-SADF) model of computation has been introduced to facilitate the analysis of dynamic streaming applications. FSM-SADF interprets application's execution as an execution of a sequence of static modes of operation called scenarios. Each scenario is modeled using a synchronous data ow (SDF) graph (SDFG), while a finite-state machine (FSM) is used to encode scenario...
Recently, it has been shown that hard real-time scheduling theory can be applied to streaming applications modeled as acyclic Cyclo-Static Dataflow (CSDF) graphs. However, that approach is not efficient in terms of throughput and processor utilization. Therefore, in this paper, we propose an improved hard real-time scheduling approach to schedule streaming applications modeled as acyclic CSDF graphs...
Uncontrolled charging is known to cause problems for the distributed power network even if only 10% of cars are powered by electric, so a charging system that prevents such problems will become necessary as they increase in popularity. Electric vehicle charging regimes that can provide the charge required by the user whilst supporting the grid and protecting battery health are required and are described...
Bandwidth is a shared and limited resource of the wireless LAN. The MAC protocols are mainly responsible for efficiently sharing it among all the stations. The IEEE 802.11 standard uses Distributed Coordination Function (DCF) as its default MAC protocol which employs Carrier Sense Multiple Access using Collision Avoidance (CSMA/CA) scheme with binary exponential backoff algorithm. Despite its ubiquitous...
In this paper different aspects of variability in a job scheduling system are discussed. Unlike an ideal manufacturing system a real-world system requires an efficient mix of different buffers to balance the influence of variability. The focus in this paper is to observe the effects of non-uniformity of processing times on the performance measures Makespan, Flowtime and Squared Variability of Completion...
Cloud hosted NoSQL data stores are for economic reasons often shared amongst multiple tenants simultaneously. The NoSQL provider consolidates multiple tenants access into a shared NoSQL instance and provides a dedicated view for each tenant. This multi-tenancy has tenants' data and workloads coexisting in the same node, which under certain conditions can lead to performance degradation of one tenant...
Scheduling algorithms published in the scientific literature are often difficult to evaluate or compare due to differences between the experimental evaluations in any two papers on the topic. Very few researchers share the details about the scheduling problem instances they use in their evaluation section, the code that allows them to transform the numbers they collect into the results and graphs...
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