Improved Spectrum Mobility using Virtual Reservation in Collaborative Cognitive Radio Networks

Cognitive radio technology would enable a set of secondary users (SU) to opportunistically use the spectrum licensed to a primary user (PU). On the appearance of this PU on a specific frequency band, any SU occupying this band should free it for PUs. Typically, SUs may collaborate to reduce the impact of cognitive users on the primary network and to improve the performance of the SUs. In this paper, we propose and analyze the performance of virtual reservation in collaborative cognitive networks. Virtual reservation is a novel link maintenance strategy that aims to maximize the throughput of the cognitive network through full spectrum utilization. Our performance evaluation shows significant improvements not only in the SUs blocking and forced termination probabilities but also in the throughput of cognitive users.Comment: 7 pages, 10 figures, IEEE ISCC 201

Prototyping and evaluating SDN-based multicast architectures for live video streaming [Demo]

Software Defined Networking (SDN) is an emerging approach for network programmability, with the capacity to initialize, control, change, and manage network behavior dynamically via open interfaces. The rise of SDN presents an opportunity to overcome the limitations of rigid and static traditional Internet architecture and provide services like inter-domain network layer multicast for live video streaming. In this demonstration we present a platform to evaluate and compare SDN-based multicast architectures for live streaming and benchmark their performance against standard IP unicast. The platform is equipped with two graphical user interfaces (GUI). A Panoramic UI provides a mechanism to modify various evaluation parameters and monitor the effect on output in form of graphs and live statistics. An Animator UI displays traffic flows over the chosen network topology and offers packet level information for the ongoing video streams. We also present a prototype of mCast implemented on our platform. mCast is a novel SDN-based multicast architecture for live video streaming over the Internet. The feedback from our platform and its GUIs showcases how mCast can save network and system resources while improving the video quality for clients

mCast: An SDN-based resource-eficient live video streaming architecture with ISP-CDN collaboration

The rise of Software Defined Networking (SDN) presents an opportunity to overcome the limitations of rigid and static traditional Internet architecture and provide services like network layer multicast for live video streaming. In this paper we propose mCast, an SDN-based architecture for live streaming, to reduce the utilization of network and system resources for both Internet Service Providers (ISP) and Content Delivery Networks (CDN) by using multicast over the Internet. We propose a communication framework between ISPs and CDNs to enable mCast while retaining user and data privacy. mCast is transparent to the clients and maintains the control of CDNs on user sessions. We developed a testbed and performed large scale evaluation and comparison. Results showed that mCast can improve the video quality received by clients and, for CDNs and ISPs in comparison to IP unicast, mCast can decrease link utilization by more than 50% and network losses to 0%

ARBITER: Adaptive rate-based intelligent HTTP streaming algorithm

Dynamic Adaptive streaming over HTTP (DASH) is widely used by content providers for video delivery and dominates traffic on cellular networks. The inherent variability in both video bitrate and network bandwidth negatively impacts the user Quality of Experience (QoE), motivating the design of better DASH-compliant adaptation algorithms. In this paper we present ARBITER, a novel streaming adaptation algorithm that explicitly integrates the variations in both video and network dynamics in its adaptation decisions. Our simulation-based performance evaluation, using real video content and cellular bandwidth traces, shows that ARBITER achieves an excellent tradeoff among streaming metrics in terms of received video quality, stall count, stall duration, and switching dynamics, leading to a relative improvement of 17-45% in user QoE in comparison to state-of-the-art algorithms

Sizing network buffers: an HTTP Adaptive Streaming perspective

HTTP Adaptive video Streaming (HAS) is the dominant traffic type on the Internet. When multiple video clients share a bottleneck link many problems arise, notably bandwidth underutilisation, unfairness and instability. Key findings from previous papers show that the "ON-OFF" behaviour of adaptive video clients is the main culprit. In this paper we focus on the network, and specifically the effects of network queue size when multiple video clients share network resources. We conducted experiments using the Mininet virtual network environment streaming real video content to open-source GPAC video clients. We explored how different network buffer sizes, ranging from 1xBDP to 30xBDP (bandwidth-delay-product), affect clients sharing a bottleneck link. Within GPAC, we implemented the published state-of-the-art adaptive video algorithms FESTIVE and BBA-2. We also evaluated impact of web cross-traffic. Our main findings indicate that the "rule-of-thumb" 1xBDP for network buffer sizing causes bandwidth underutilisation, limiting available bandwidth to 70% for all video clients across different round-trip-times (RTT). Interaction between web and HAS clients depends on multiple factors, including adaptation algorithm, bitrate distribution and offered web traffic load. Additionally, operating in an environment with heterogeneous RTTs causes unfairness among ompeting HAS clients. Based on our experimental results, we propose 2xBDP as a default network queue size in environments when multiple users share network resources with homogeneous RTTs. With heterogeneous RTTs, a BDP value based on the average RTTs for all clients improves fairness among competing clients by 60%

Datasets for AVC (H.264) and HEVC (H.265) evaluation of dynamic adaptive streaming over HTTP (DASH)

In this paper we present datasets for both trace-based simulation and real-time testbed evaluation of Dynamic Adaptive Streaming over HTTP (DASH). Our trace-based simulation dataset provides a means of evaluation in frameworks such as NS-2 and NS-3, while our testbed evaluation dataset offers a means of analysing the delivery of content over a physical network and associated adaptation mechanisms at the client. Our datasets are available in both H.264 and H.265 with encoding rates comparative to the representations and resolutions of content distribution providers such as Netflix, Hulu and YouTube. The goal of our dataset is to provide researchers with a sufficiently large dataset, in both number, and duration, of clips which provides a comparison between both encoding schemes. We provide options for evaluating not only different content and genres, but also the underlying encoding metrics, such as transmission cost, segment distribution (the range of the oscillation of the segment sizes) and associated delivery issues such as jitter and re-buffering. Finally, we also offer our datasets in a header-only compressed format, which allows researchers to download the entire dataset and uncompress locally, thus ensuring that our datasets are accessible both online via remote and local servers

Effect of weeding status and tapping date on the yield of gum Arabic (Acacia Senegal) in Jigawa state, Nigeria

The study examined the Effect of Weeding Status and Tapping Date on the yield of gum Arabic (Acacia senegal) in Jigawa State, Nigeria. The said task has been accomplished by employing a two factorial experiment of complete randomized block design with three replicates which involves the weeding status and tapping dates conducted in 2014 season at two different locations; Kadoma and Kwanar duhuwa. The weeding status experiment comprises of three 100% weeded plots; and three Unwweded plots; while the tapping date investigation was tested at six levels (1st and 15th September, 1st and 5th October and 1st and 15th November). In each of these treatments three (3) trees were tapped making a total number of two hundred and sixteen trees in the two locations and one hundred and eight (108) trees at kadoma and Kwanar duhuwa respectively. The first picking of the gum yield took place 45day after tapping and each consecutive picking was collected after 15 days from the previous one. The gum from each picking was weighed after air drying with sensitive balance JY2002 model. SAS statistical package used for the data analysis thus DUNCAN multiple range test were employed in establishing the relationships between the variable investigated.Thus, the finding has revealed that gum Arabic tapping conducted on the 15th of October gave higher yield of gum Arabic when compared with the rest dates of tapping; the unweeded plots gave superior yield than the weeded plot.Therefore gum Arabic farmers were advised not to weed gum Arabic field when they are matured enough for harvest at the same time tapping should be carried out when the gum Arabic tree lost at least 50% of their leaves.Keywords; Gum Arabic, Jigawa State, Tapping and Weeding

Prototyping and evaluating SDN-based multicast architectures for live video streaming [poster presentation]

Significance: Internet video to TV will continue to grow at a rapidpace, increasing 3.6-fold by 2020. Live video streaming services constitute of 40 per cent of consumer Internet video traffic. [Cisco2015] Contribution: A generic platform to evaluate and compare various SDN-based multicast architectures or algorithms. Benchmark the performance against standard IP unicast. Provide a mechanism to modify various evaluation parameters and monitor the effect on output in form of graphs and live statistics. Implement a prototype of mCast and compare it with IP unicast

RTOP: optimal user grouping and SFN clustering for multiple eMBMS video sessions

Evolved Multimedia Broadcast Multicast Service (eMBMS) is a 3GPP standard that improves the utilization of scarce wireless resources and the quality of the received content. eMBMS uses a Single Frequency Network (SFN) to transmit real-time videos over synchronized resources across neighboring base stations (eNBs) and allows users to share wireless spectrum across multiple cell sites. However the user with the worst channel condition and the eNB with the least available resources limit the throughput of a session. To overcome such limitations, the SFN can be divided into non-overlapping clusters of eNBs and in each cluster users can be split into groups. We formulate an optimization problem that maximizes an operator-defined utility for multiple eMBMS sessions served at multiple bitrates by choosing the optimal set of SFN clusters and user groups for each session. We propose an algorithm, RTOP, that finds the optimal or a near-optimal solution in real-time regardless of the number of eMBMS users. Our extensive simulations indicate that, in comparison to state-of-the-art schemes, RTOP improves the system utility and average user bitrate by up to 14% and 90% respectively. Additionally, we show that the utility of RTOP always stays within a 1% gap from the optimal solution