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Multipath TCP (MPTCP) is an evolvable technology for bandwidth aggregation on a mobile device. MPTCP naturally and concurrently exploits wireless links via different interfaces (i.e., Wi-Fi and cellular) for data transferring. Theoretically, the MPTCP's aggregated throughput is better or at least equals to the TCP throughput over a link. However, our investigation of MPTCP performance in a lossy wireless...
The number of devices enhanced with wireless communication capabilities is increasing at a fast pace. Such increase has exacerbated the quest for efficient medium access control protocols. In fact, the possibility of providing concurrent access to multiple channels, thus increasing throughput and reducing channel access delays, has been widely investigated. Among the alternatives for providing multi-channel...
In this paper, QoS characteristics such as TCP throughput is investigated for densely deployed mobile wireless LANs (WLANs). Factors affecting throughput characteristics are discussed and evaluated by using real machines such as smartphones and portable APs. In IEEE 802.11 WLANs, a rate adaptation mechanism controls the transmission rate and one of the dominant factors for QoS. In order to understand...
The emerging software defined networking (SDN) provides a new paradigm of network management by separating control functionalities from underlying data forwarding hardware to an external controller. SDN provides high flexibility to control the whole network in a unified way. In this paper, we are motivated to study the performance issues of a software defined WiFi network testbed. This testbed consists...
In this paper, we study the throughput of compressive random access for machine type communications (MTC) and compare it with that of multi-channel ALOHA. In compressive random access, the sparsity of active devices is exploited to use compressive sensing (CS) based low-complexity multiuser detection (MUD) when non-orthogonal spreading codes are used to support a number of devices. For tractable analysis,...
This work presents a new backoff algorithm, namely Maximum Throughput and Fairness aware Backoff (MTFB), for IEEE 802.11 wireless LANs. The algorithm adaptively adjusts the contention window (CW) size so that the maximum throughput and fairness can be maintained even with large number of active stations (STAs). In mixed environments with the legacy 802.11 devices the algorithm is able to keep the...
WiFi networks have becoming popular in the past decade to provide network access due to its inexpensive but high-bandwidth infrastructure. With the increasingly dense WiFi deployment and the rapid proliferation of network devices and applications, the demand for more bandwidth, constrained delay performance and less power consumption is soaring; however, the traditional WiFi networks have become incapable...
We present a simulation-based study of the impacts of channel switching overhead on the performance of multicast in multi-channel multi-radio wireless mesh networks (MCMR WMNs). We study how channel switching overhead affects the performance metrics such as packet delivery ratio, throughput, end-to-end delay, and delay jitter of a multicast session.
FPGA, or Field Programmable Gate Array, has been widely used for several applications such as digital signal and image processing, video processing, software-defined radio, radar processing, medical imaging and so on. Currently, with the significance growth of parallel computing and cloud computing application, FPGA provides another solution for high performance computing instead of CPU or GPGPU due...
Machine-Type-Communication (MTC), also known as Machine to Machine (M2M) communication is one of the emerging technologies in mobile broadband networks such as LTE (Long Term Evolution) known as a key technology for the future. Several problems occur in the presence of massive M2M communications, such as the congestion at the radio access because of simultaneous signals or data messages sent from...
We propose and design a new Block I/O schedulingscheme called Bulk I/O Dispatch (BID) suited for disk intensiveMapReduce applications. Large data access by such applicationsresult in a large number of block I/O requests which have thepotential to be sequentialized. However, due to contention byother applications and the way current I/O schedulers operate, the opportunities of a large sequential I/Os...
When SSDs are used for in-situ execution of data-intensive scientific workflows, it is challenging to obtain consistently high I/O throughput because its I/O efficiency can be compromised for serving write and read requests simultaneously. This issue is so-called write-read interference. In this paper, we propose a novel scheme named FlashStager, which can isolate writes from reads using write redirection...
Carrying out even the simplest performance benchmark requires considerable knowledge of statistics and computer systems, and painstakingly following many error-prone steps, which are distinct skill sets yet essential for getting statistically valid results. As a result, many performance measurements in peer-reviewed publications are flawed. Among many problems, they fall short in one or more of the...
It is expected that billions of devices will be connected with each other through the Internet of Things (IoT). Different aspects of IoT, such as security, have been extensively explored in the literature. However, the research focuses on how to identify and secure the IoT. We believe that it is very important to investigate how the IoT infrastructure will response when a huge amount of data is generated...
The patient monitoring through implant medical devices under medical implant communication service (MICS) band has significantly increased due to growing healthcare expenses, an aging population, and successful deployment of wearable home-based medical monitoring in telemedicine. Recent literature lacks the performance evaluation mechanisms and discussion of MICS band in terms of quality of service...
File system metadata is indispensable in both describing the data and maintaining the file system. Despite the importance of metadata in the file system, the overhead of maintaining the metadata cannot be taken lightly. It is because the metadata also have to be persisted on the storage device and it consumes IO bandwidth as well as creates journaling overhead. In this paper, we find that the random...
This paper proposes an asynchronous transmission WDMA protocol for passive star optical networks, considering the propagation delay effect. We aim to reduce the rejection probability at destination due to the receiver collisions and consequently to enhance the system throughput, by assuming two -instead of one-tunable receivers per node. An analytical model is developed for the performance evaluation,...
A new recursive shared segmented split multiply-accumulate (MAC) unit have been proposed which can be deployed in high speed DSP applications like Fast Fourier Transform (FFT), Discrete Cosine Transform (DCT), Wavelet Transform (WT) and digital filtering. This paper presents two design aspects, the former presents the design of new parallel prefix adder which is responsible in the generation of partial...
Networks have been expanding in scale and speeds, however, it is difficult to troubleshoot network problems because of specific measurement policies and services in different administrative domains. Moreover, many network issues are very subtle, e.g. a link becomes increasing slow but still connected, where active measurement is instrumental. While many measurement infrastructures have been developed...
Abnormal oscillatory movement (i.e. tremor) is usually evaluated with qualitative assessment by clinicians, and quantified with subjective scoring methods. These methods are often inaccurate. We utilized a quantitative and standardized task based on the Fitts' law to assess the performance of arm movement with tremor by controlling a gyration mouse on a computer. The experiment included the center-out...
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