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With the exponential growth of the mobile video traffic and the dramatic diversity of wireless channels among users, maintaining a tradeoff between resource consumption and perceived experience of users is of overwhelming challenges. Dynamic Adaptive Streaming over HTTP(DASH), as a promising technique to improve the video transmission efficiency, achieves bitrate adaption at users' ends to accommodate...
We investigate the overlay coding scheme as the capacity achieving multi user detection (MUD) technique, i.e., transmitting over non-orthogonal channels, in forward link in multi-beam satellite systems with dense frequency reuse. The classic overlay coding scheme, uses the strongest co- channel interference (CCI) as extra source of information. The data intended for the target user is shared between...
The cellular data traffic has been dramatically increased, a typical approach is considering the operation of the Long Term Evolution (LTE) system in the unlicensed spectrum. Although there are a large number of theoretical researches on LTE-U, field trial results are still lacking. In this paper, we build a real time field trial in 5.8GHz unlicensed bands. The typical indoor scenario is deployed...
Data movement to and from off-chip memory dominates energy consumption in most video decoders, with DRAM accesses consuming 2.8x–6x more energy than the processing itself. We present a H.265/HEVC video decoder with embedded DRAM (eDRAM) as main memory. We propose the following techniques to optimize data movement and reduce the power consumption of eDRAM: 1) lossless compression is used to store reference...
In this work, we introduce a powerful hardware-based rogue access point (PrAP), which can relay traffic between a legitimate AP and a wireless station back and forth, and act as a man-in-the-middle attacker. Our PrAP is built of two dedicated wireless routers interconnected physically, and can relay traffic rapidly between a station and a legitimate AP. Through extensive experiments, we demonstrate...
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....
Licensed-Assisted Access (LAA) is a new operation mode for the Long Term Evolution Advanced systems to transmit data via both licensed spectrum and unlicensed spectrum based on the framework of carrier aggregation. For LAA uplink (UL) transmission, there is a mismatch between resource allocation and actual data transmission due to the requirement of listen-before-talk (LBT). Such a mismatch may cause...
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...
Wi-Fi is the dominant wireless indoor broadband solution and thus key for meeting the exponential traffic growth. The recent IEEE 802.11ac amendment enables PHY data rates exceeding 1 Gbps. However, it is not clear how this increased per-link performance, achieved especially via wider channels, translates to network-level performance. The latter is crucial for understanding the true potential of emerging...
The lower layer characteristics of 60 GHz wireless networks impact the entire protocol stack. This includes effects such as sudden link failure due to blockage, high packet loss due to deafness, or suboptimal transmit rates due to antenna misalignment. To understand the resulting behaviors at the upper layers, it is key to have access to lower layer information. At the time of writing, 60 GHz experimentation...
Upload and download traffic often coexist in mobile networks. However, TCP download throughput could be substantially degraded by upload traffic even if the downlink is not the bottleneck. Previous works such as RSFC and TCP-RRE can substantially improve TCP download throughput in the presence of concurrent TCP upload flows, albeit at the expense of significantly degraded upload throughput performance...
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...
Due to the widespread use of broadband communication media, it is often the case that the conventional TCP cannot fully utilize such broad bandwidth; hence, many improvements on TCP itself and a lot of accelerating methods which use multiple TCP flows have been proposed. In addition, video hosting services on the Internet as a new medium have become popular, and progressive downloading methods, which...
We tackle the problem of a network switch enforcing fair bandwidth sharing of the same link among many TCP-like senders. Most of the mechanisms to solve this problem are based on complex scheduling algorithms, whose feasibility becomes very expensive with today's line rate requirements, i.e. 10–100 Gbit/s per port. We propose a new scheme called FDPA in which we do not modify the scheduler, but instead...
We consider the practical problem of video surveillance in public transport systems, where security videos are stored onboard, and a central operator occasionally needs to access portions of the recordings. When this happens, the selected video must be uploaded within a deadline, possibly using multiple parallel wireless interfaces. Interfaces have different associated costs, related to tariffs charged...
To take advantage of software defined networking (SDN) within a limited budget constraint, a natural strategy is to incrementally deploy a few SDN switches (and a limited amount of additional link bandwidth) into the legacy optical network. In such a hybrid optical network, operators can only change the routes of flows that traverse SDN switches. Therefore, to optimize SDN deployment, it is essential...
In the era of global-scale services, analytical queries are performed on datasets that span multiple data centers (DCs). Due to the scarce and expensive inter-DC bandwidth, various methods have been proposed to reduce either the traffic cost or the completion time for those analytics queries. However, current methods make no attempt to maximize the number of successfully served query requests. Moreover,...
RAM-based storage aggregates the RAM of servers in data center networks (DCN) to provide extremely high storage performance. For quick recovery of storage server failures, Mem-Cube [1] exploits the proximity of the BCube network to limit the recovery traffic to the recovery servers' 1-hop neighborhood. However, previous design is applicable only to BCube, and has suboptimal recovery performance due...
The Dynamic Adaptive Streaming over HTTP (DASH) is specified to cope with the changing network conditions and provide an adaptive bit-rate HTTP-based streaming solution. While there have been many researches of rate adaptation algorithms on adaptive HTTP streaming, much of the work is focused on Video on Demand (VoD) service — which is not same as live streaming. It is generally preferred to minimize...
Video streaming takes the lion's share of network bandwidth, with a trend that will likely increase in the future. In the recent years, dynamic adaptive streaming has been developed to offer a smooth video stream with variable quality, depending on the performance of the network connection. At present, several content providers like Netflix, YouTube and Hulu, to name a few, already offer videos that...
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