Self-optimizing load balancing with backhaul-constrained radio access networks

Self-Organizing Network (SON) technology aims at autonomously deploying, optimizing and repairing the Radio Access Networks (RAN). SON algorithms typically use Key Performance Indicators (KPIs) from the RAN. It is shown that in certain cases, it is essential to take into account the impact of the backhaul state in the design of the SON algorithm. We revisit the Base Station (BS) load definition taking into account the backhaul state. We provide an analytical formula for the load along with a simple estimator for both elastic and guaranteed bit-rate (GBR) traffic. We incorporate the proposed load estimator in a self-optimized load balancing algorithm. Simulation results for a backhaul constrained heterogeneous network illustrate how the correct load definition can guarantee a proper operation of the SON algorithm.Comment: Wireless Communications Letters, IEEE, 201

Self Organizing strategies for enhanced ICIC (eICIC)

Small cells have been identified as an effective solution for coping with the important traffic increase that is expected in the coming years. But this solution is accompanied by additional interference that needs to be mitigated. The enhanced Inter Cell Interference Coordination (eICIC) feature has been introduced to address the interference problem. eICIC involves two parameters which need to be optimized, namely the Cell Range Extension (CRE) of the small cells and the ABS ratio (ABSr) which defines a mute ratio for the macro cell to reduce the interference it produces. In this paper we propose self-optimizing algorithms for the eICIC. The CRE is adjusted by means of load balancing algorithm. The ABSr parameter is optimized by maximizing a proportional fair utility of user throughputs. The convergence of the algorithms is proven using stochastic approximation theorems. Numerical simulations illustrate the important performance gain brought about by the different algorithms.Comment: Submitted to WiOpt 201

Transboundary threats in the Mekong basin: protecting a crucial fishery

This repository item contains a single issue of Issues in Brief, a series of policy briefs that began publishing in 2008 by the Boston University Frederick S. Pardee Center for the Study of the Longer-Range Future.In this Issues in Brief, Pardee Center Visiting Research Fellow Irit Altman looks at the impacts that dams in the upper Mekong River basin have on the critically important fishery in Cambodia’s Tonle Sap, the largest freshwater lake in Southeast Asia. Altman explores how development of dams, in combination with a failure of regional governance, has threatened the ecological sustainability of the lake and its watershed, and the livelihoods of people in the region. She identifies strategies to enhance the resilience of the Tonle Sap fishery and improve the lives of people who are connected to this unique ecosystem. Irit Altman is a Pardee Center Visiting Research Fellow and Research Assistant Professor of Biology at Boston University. A marine and freshwater ecologist, she works with an interdisciplinary research team to develop ecosystem models that integrate scientific knowledge and inform decision-making. She has extensive experience working with field experts and decision makers in Cambodia to understand system change and explore sustainability options in the Tonle Sap ecosystem

Transformative Effects of NDIIPP, the Case of the Henry A. Murray Archive

This article comprises reflections on the changes to the Henry A. Murray Research Archive, catalyzed by involvement with the National Digital Information Infrastructure and Preservation Program (NDIIPP) partnership, and the accompanying introduction of next generation digital library software. Founded in 1976 at Radcliffe, the Henry A. Murray Research Archive is the endowed, permanent repository for quantitative and qualitative research data at the Institute for Quantitative Social Science, in Harvard University. The Murray preserves in perpetuity all types of data of interest to the research community, including numerical, video, audio, interview notes, and other types. The center is unique among data archives in the United States in the extent of its holdings in quantitative, qualitative, and mixed quantitativequalitative research. The Murray took part in an NDIIPP-funded collaboration with four other archival partners, Data-PASS, for the purpose of the identification and acquisition of data at risk, and the joint development of best practices with respect to shared stewardship, preservation, and exchange of these data. During this time, the Dataverse Network (DVN) software was introduced, facilitating the creation of virtual archives. The combination of institutional collaboration and new technology lead the Murray to re-engineer its entire acquisition process; completely rewrite its ingest, dissemination, and other licensing agreements; and adopt a new model for ingest, discovery, access, and presentation of its collections. Through the Data-PASS project, the Murray has acquired a number of important data collections. The resulting changes within the Murray have been dramatic, including increasing its overall rate of acquisitions by fourfold; and disseminating acquisitions far more rapidly. Furthermore, the new licensing and processing procedures allow a previously undreamed of level of interoperability and collaboration with partner archives, facilitating integrated discovery and presentation services, and joint stewardship of collections.published or submitted for publicatio

Internal Structure of Addition Chains: Well-Ordering

An addition chain for $n$ is defined to be a sequence $(a_0,a_1,\ldots,a_r)$ such that $a_0=1$, $a_r=n$, and, for any $1\le k\le r$, there exist $0\le i, j<k$ such that $a_k = a_i + a_j$; the number $r$ is called the length of the addition chain. The shortest length among addition chains for $n$, called the addition chain length of $n$, is denoted $\ell(n)$. The number $\ell(n)$ is always at least $\log_2 n$; in this paper we consider the difference $\delta^\ell(n):=\ell(n)-\log_2 n$, which we call the addition chain defect. First we use this notion to show that for any $n$, there exists $K$ such that for any $k\ge K$, we have $\ell(2^k n)=\ell(2^K n)+(k-K)$. The main result is that the set of values of $\delta^\ell$ is a well-ordered subset of $[0,\infty)$, with order type $\omega^\omega$. The results obtained here are analogous to the results for integer complexity obtained in [1] and [3]. We also prove similar well-ordering results for restricted forms of addition chain length, such as star chain length and Hansen chain length.Comment: 19 page

Intermediate arithmetic operations on ordinal numbers

There are two well-known ways of doing arithmetic with ordinal numbers: the "ordinary" addition, multiplication, and exponentiation, which are defined by transfinite iteration; and the "natural" (or Hessenberg) addition and multiplication (denoted $\oplus$ and $\otimes$), each satisfying its own set of algebraic laws. In 1909, Jacobsthal considered a third, intermediate way of multiplying ordinals (denoted $\times$), defined by transfinite iteration of natural addition, as well as the notion of exponentiation defined by transfinite iteration of his multiplication, which we denote $\alpha^{\times\beta}$. (Jacobsthal's multiplication was later rediscovered by Conway.) Jacobsthal showed these operations too obeyed algebraic laws. In this paper, we pick up where Jacobsthal left off by considering the notion of exponentiation obtained by transfinitely iterating natural multiplication instead; we will denote this $\alpha^{\otimes\beta}$. We show that $\alpha^{\otimes(\beta\oplus\gamma)} = (\alpha^{\otimes\beta}) \otimes(\alpha^{\otimes\gamma})$ and that $\alpha^{\otimes(\beta\times\gamma)}=(\alpha^{\otimes\beta})^{\otimes\gamma}$; note the use of Jacobsthal's multiplication in the latter. We also demonstrate the impossibility of defining a "natural exponentiation" satisfying reasonable algebraic laws.Comment: 18 pages, 3 table