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 design and implement a novel system called Async, which enables a mobile network operator (MNO) to efficiently manage the growth of mobile data by leveraging the delay-elastic nature of certain applications and the price-sensitive nature of certain users. Specifically, Async introduces an alternate “asynchronous” content-delivery paradigm for heavy content (e.g., videos), and facilitates an MNO to negotiate with users a delay in delivery in exchange for appropriate incentives. The MNO uses the negotiated delays to actively manage Async flows to reduce congestion and improve the quality-of-experience (QoE) of both delayed and regular flows. We show that in comparison to state-of-the-art, Async's network-based flow management enhances QoE for more than 30% of the regular flows, with up to 60% improvement in per-flow QoE metric, while still meeting the negotiated delivery times of 95% of the delayed flows. Async also lowers the delivery times of delayed flows by ∼67% and significantly increases robustness to traffic unpredictability. Our design is robust to disconnections and does not require any modifications to existing network infrastructure and protocols. Our prototype deployment (using Apache's mod_proxy and an Android app) on live networks confirms Async's efficacy in meeting EDTs for diverse deployment scenarios.

Async: De-congestion and yield management in cellular data networks

The development of the IEEE 802.16 mobile broadband wireless access or WiMAX standards promises to usher the next generation of mobile wireless networks. There is considerable ongoing interest in evaluating the performance of such networks with simulations forming the primary tool for conducting such studies. This paper presents the design and implementation of the Medium Access Control (MAC) and Physical layers of WiMAX based on IEEE802.16e standard on the ns-2 network simulator. Appropriate abstractions and methodologies are carefully chosen to ensure the maximal conformance of simulation to reality while keeping the computational complexity acceptable. Results that validate the accuracy of the simulator as well as those that describe its performance are presented.

/pdf/wimax-system-design-and-evaluation-methodology-using-the-ns-e09wwkn68o.pdf

WiMAX system design and evaluation methodology using the NS-2 simulator

As wireless networks are deployed widely and user expectations grow, it is important to study the trade-offs among goodput, latency and loss rates that exist in link and transport protocols. Under low residual loss rates, retransmissions can be effective in bringing down the loss rate. However, at high loss rates, current links trade-off goodput and low latency for a small loss rate which diminishes overall performance. We look at the performance at the link and transport layers in the presence of raw loss and see how current protocols make an unattractive trade-off at the link layer. We also show high ARQ on the link can cause high per-packet latency on the link which can lead to interactions with TCP mechanisms leading to spurious retransmissions and timeouts and reduced TCP-layer goodput. Our measurements results, based on experiments conducted on the ORBIT testbed, show the need for modifications to the link layer to obtain a favorable three-way trade-off. In prior work, we have developed link and transport protocols that are designed to work under high loss rates. Our link design LL-HARQ (hybrid FEC/ARQ) is designed to minimize the link delay while exporting a very small residual loss rate and high goodput while our transport protocol Loss-Tolerant TCP is designed to operate over a wide range of residual loss rates. We provide insights about the balance between error-protection functions at the two layers and examine the case for cross-layer co-operation. The measurement traces were used as inputs to our simulations on the ns-2 simulator. Our results show the favorable trade-offs among goodput/latency/loss rate obtained with our approach over traditional approaches.

Experimental study of link and transport protocols in interference-prone wireless LAN environments

With the energy consumption of buildings trending upwards and energy prices rising, several commercial establishments are finding that their energy bills are fast becoming a significant part of their operational budget. In this paper, we describe the practical lessons learnt when the facility manager of a large office building in Australia was considering the of use of renewables to reduce the building's peak demand. We first illustrate how analytics can use used on data gathered by a building management system (BMS) to yield rich insights into the factors affecting the building's peak demand. We then describe the efficacy of solar PV and battery storage systems in alleviating the peak demand. We believe that the lessons learnt from our experience: (i) are generic as it informs facility managers of key factors to consider when incorporating renewables, and (ii) provides holistic guidelines when integrating solar PV and battery storage for reducing a building's peak demand and operating energy costs.

Using renewables to reduce peak demand: Lessons from an Australian experience

The technological advances in recent years are allowing Internet Service Providers (ISPs) to provide Quality of Service (QoS) assurance for traffic through their domains. This article develops a spot pricing framework for intra-domain expected bandwidth contract with a loss based QoS guarantee. The framework accounts for both the cost and the risks associated with QoS delivery. A nonlinear pricing scheme is used in pricing for cost recovery; a utility based options pricing approach is developed for risk related pricing. The application of options pricing in internet services provides a mechanism for fair risk sharing between the provider and the customer, and may be extended to price other uncertainties in QoS guarantees.

Shivkumar Kalyanaraman

Papers

Async: De-congestion and yield management in cellular data networks

WiMAX system design and evaluation methodology using the NS-2 simulator

Experimental study of link and transport protocols in interference-prone wireless LAN environments

Using renewables to reduce peak demand: Lessons from an Australian experience

Simulation for risk management: a two-component spot pricing framework for loss-rate guaranteed internet service contracts