THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

What will 5G be? What it will not be is an incremental advance on 4G. The previous four generations of cellular technology have each been a major paradigm shift that has broken backward compatibility. Indeed, 5G will need to be a paradigm shift that includes very high carrier frequencies with massive bandwidths, extreme base station and device densities, and unprecedented numbers of antennas. However, unlike the previous four generations, it will also be highly integrative: tying any new 5G air interface and spectrum together with LTE and WiFi to provide universal high-rate coverage and a seamless user experience. To support this, the core network will also have to reach unprecedented levels of flexibility and intelligence, spectrum regulation will need to be rethought and improved, and energy and cost efficiencies will become even more critical considerations. This paper discusses all of these topics, identifying key challenges for future research and preliminary 5G standardization activities, while providing a comprehensive overview of the current literature, and in particular of the papers appearing in this special issue.

What Will 5G Be

Recommender systems have developed in parallel with the web. They were initially based on demographic, content-based and collaborative filtering. Currently, these systems are incorporating social information. In the future, they will use implicit, local and personal information from the Internet of things. This article provides an overview of recommender systems as well as collaborative filtering methods and algorithms; it also explains their evolution, provides an original classification for these systems, identifies areas of future implementation and develops certain areas selected for past, present or future importance.

http://romisatriawahono.net/lecture/rm/survey/information%20retrieval/Bobadilla%20-%20Recommender%20Systems%20-%202013.pdf

Recommender systems survey

Cloud data centers host diverse applications, mixing workloads that require small predictable latency with others requiring large sustained throughput. In this environment, today's state-of-the-art TCP protocol falls short. We present measurements of a 6000 server production cluster and reveal impairments that lead to high application latencies, rooted in TCP's demands on the limited buffer space available in data center switches. For example, bandwidth hungry "background" flows build up queues at the switches, and thus impact the performance of latency sensitive "foreground" traffic.To address these problems, we propose DCTCP, a TCP-like protocol for data center networks. DCTCP leverages Explicit Congestion Notification (ECN) in the network to provide multi-bit feedback to the end hosts. We evaluate DCTCP at 1 and 10Gbps speeds using commodity, shallow buffered switches. We find DCTCP delivers the same or better throughput than TCP, while using 90% less buffer space. Unlike TCP, DCTCP also provides high burst tolerance and low latency for short flows. In handling workloads derived from operational measurements, we found DCTCP enables the applications to handle 10X the current background traffic, without impacting foreground traffic. Further, a 10X increase in foreground traffic does not cause any timeouts, thus largely eliminating incast problems.

/pdf/data-center-tcp-dctcp-4d3pj8xdal.pdf

Data center TCP (DCTCP)

This paper presents and evaluates two principles for wireless routing protocols. The first is datapath validation: data traffic quickly discovers and fixes routing inconsistencies. The second is adaptive beaconing: extending the Trickle algorithm to routing control traffic reduces route repair latency and sends fewer beacons.We evaluate datapath validation and adaptive beaconing in CTP Noe, a sensor network tree collection protocol. We use 12 different testbeds ranging in size from 20--310 nodes, comprising seven platforms, and six different link layers, on both interference-free and interference-prone channels. In all cases, CTP Noe delivers > 90% of packets. Many experiments achieve 99.9%. Compared to standard beaconing, CTP Noe sends 73% fewer beacons while reducing topology repair latency by 99.8%. Finally, when using low-power link layers, CTP Noe has duty cycles of 3% while supporting aggregate loads of 30 packets/minute.

/pdf/collection-tree-protocol-selhhlblmq.pdf

Collection tree protocol

We model World Wide Web (WWW) servers and clients running over an ATM network using the ABR (available bit rate) service. The WWW servers are modeled using a variant of the SPECweb96 benchmark, while the WWW clients are based on a model by Mah. The traffic generated by this application is typically bursty, i.e., it has active and idle periods in transmission. A timeout occurs after given amount of idle period. During idle period the underlying TCP congestion windows remain open until a timeout expires. These open windows may be used to send data in a burst when the application becomes active again. This raises the possibility of large switch queues if the source rates are not controlled by ABR. We study this problem and show that ABR scales well with a large number of bursty TCP sources in the system.

Performance of Bursty World Wide Web (WWW) Sources over ABR

The increasing demand for high-quality streaming video delivered to mobile clients necessitates efficient bandwidth utilization and allocation at not only the wireless channel but also the wired backhaul of broadband wireless networks. In this context, we propose techniques for increasing the link utilization and enhancing the quality-of-experience (QoE) for end users while multiplexing video streams over a wired link. For increasing the link utilization, we present a generic multi-tiered bandwidth estimation and scheduling scheme that can guarantee lower bounds on loss for flows at lower tiers. This scheme can be used for supporting heterogeneous loss classes, differentiated losses for different layers of video streams, or per-flow guarantees using lower aggregate bandwidth than schemes proposed in the literature. For enhancing the end-user QoE, we present a scheme for minimizing correlated losses and improving the smoothness of video quality by minimizing the maximum loss suffered by any logical unit of a stream and also the variability in loss across the length of the stream. In simulations performed using MPEG-4 sources, our loss-minimization approach could lower the maximum loss by a factor of five and the loss variance by more than an order of magnitude. Our multi-tiered scheme could lower the estimated bandwidth and improve statistical multiplexing gains by 10-20% with three classes, 5--20% with two classes, and over 30% in the context of providing deterministic per-flow guarantees.

Multi-tiered, burstiness-aware bandwidth estimation and scheduling for VBR video flows

Information comes in two general flavors: non-executable (a string of bits with predefined meaning and already in their final form) and executable (bits of program code, intended to be executed, and whose result after execution is of primary interest). Our understanding of non-executable information is relatively deep and well known. Characteristics and behavior of executable information, on the contrary, is far from known: no one can say in general when the smallest program that performs a task has been generated—no one can predict the impact of changes to the bits of program code—no one can determine in general when or if a program will end; most practitioners steer clear of applying it within the network and even fewer researchers explore algorithmic information theory with respect to managing a network. Active networks [1‐3] provide a framework enabling the previously discussed flavors of information to co-exist within, and modify the behavior of, communication networks. Executable code and non-executable data reside within network packets such that injected code can modify behavior of lowlevel network layers. Programmable networks allow customization of dataplane and control-plane services (e.g., using network processor methods in high-speed routers or software radio methods in wireless networks). These networks raise new management issues regarding the relation and tradeoffs among communication and computation, configuration, fault, security, performance, and accounting management. Ad hoc wireless networks and software radios are being facilitated by the advancement of active networks; however, they add another level of complexity to active and programmable network management.

Management of Active and Programmable Networks

Soil moisture and temperature are key inputs to several precision agricultural applications such as irrigation scheduling, identifying crop health, pest and disease prediction, yield and acreage estimation, etc. The existing remote sensing satellites based soil moisture products such as SMAP are of coarse resolution and physics based land surface model such as NL-DAS, GLDAS are also of coarse resolution as well as not available for real time applications. Keeping this in focus, we have customized high resolution land data assimilation system (HRLDAS) for India. The customization involve: (1) use of Global Data Assimilation System (GDAS) dataset for dynamic forcing fields, (2) ability to ingest local information about the soil characteristics (3) high resolution USGS land-cover and other static datasets, amongst others. In this paper, we present the performance of the customized model against SMAP soil moisture data and local sensors observations. The first results from the comparison shows a significantly reduced errors in model results. The RMSE for LSM generated outputs are less than 2%, whereas SMAP gives 4–5 % error for soil moisture.

Evaluation of Land Surface Model Against Smap and In-Situ Observations for Indian Region

An additive-increase-multiplicative-decrease (AIMD) type of algorithm has been popular in network congestion control. The stability and performance of the algorithm has been analyzed for the single bottleneck network model. This paper considers the impact of time delay on the performance of the AIMD algorithm applied to the rate control of a single bottleneck, multiple-source network. An estimate of the worst case queue length is derived which can be used to allocate buffers at bottlenecks to avoid loss. This bound is nonconservative in the sense that there is an initial source rate distribution that can lead to this queue length.

Shivkumar Kalyanaraman

Papers

Performance of Bursty World Wide Web (WWW) Sources over ABR

Multi-tiered, burstiness-aware bandwidth estimation and scheduling for VBR video flows

Management of Active and Programmable Networks

Evaluation of Land Surface Model Against Smap and In-Situ Observations for Indian Region

Effect of time delay in network traffic control