Millimeter Wave Cellular Networks: A MAC Layer Perspective

The millimeter wave (mmWave) frequency band is seen as a key enabler of multi-gigabit wireless access in future cellular networks. In order to overcome the propagation challenges, mmWave systems use a large number of antenna elements both at the base station and at the user equipment, which lead to high directivity gains, fully-directional communications, and possible noise-limited operations. The fundamental differences between mmWave networks and traditional ones challenge the classical design constraints, objectives, and available degrees of freedom. This paper addresses the implications that highly directional communication has on the design of an efficient medium access control (MAC) layer. The paper discusses key MAC layer issues, such as synchronization, random access, handover, channelization, interference management, scheduling, and association. The paper provides an integrated view on MAC layer issues for cellular networks, identifies new challenges and tradeoffs, and provides novel insights and solution approaches.Comment: 21 pages, 9 figures, 2 tables, to appear in IEEE Transactions on Communication

An Appropriate Parameterized Utility Technique On Heterogeneous Server Dependencies

A new server-based approach incorporated in Heterogeneous Servers. Current cloudinfrastructures are mostly homogeneous composed of a large number of machines of the same type – centrally managed and made available to the end user.In a cloud computing pattern, multiple resources types were utilizing. Users may have diverse resource needs. Furthermore, diversity in server properties/capabilities may mean that only a subset of servers may be usable by a given user. In platforms with such heterogeneity, we identify important limitations in existing multi-resource fair allocation mechanisms, notably Dominant Resource Fairness and its follow-up work. To overcome such limitations, we propose a new server-based approach; each server allocates resources by maximizing a per-server utility function. We propose a specific class of utility functions which, when appropriately parameterized, adjusts the trade-off between efficiency and fairness, and captures a variety of fairness measures. We establish conditions for the proposed mechanism to satisfy certain properties that are generally deemed desirable, e.g., envy-freeness, sharing incentive, bottleneck fairness, and Pareto optimality. To implement resource parameterized mechanism, we develop an iterative algorithm which is shown to be globally convergent on Heterogeneous server dependencies

A Cross-layer Framework for Multiobjective Performance Evaluation of Wireless Ad Hoc Networks

International audienceIn this paper we address the problem of finding the optimal performance region of a wireless ad hoc network when multiple performance metrics are considered. Our contribution is to propose a novel cross-layer framework for deriving the Pareto optimal performance bounds for the network. These Pareto bounds provide key information for understanding the network behavior and the performance trade-offs when multiple criteria are relevant. Our approach is to take a holistic view of the network that captures the cross-interactions among interference management techniques implemented at various layers of the protocol stack (e.g. routing and resource allocation) and determines the objective functions for the multiple criteria to be optimized. The resulting complex multiobjective optimization problem is then solved by multiobjective search techniques. The Pareto optimal sets for an example sensor network are presented and analyzed when delay, reliability and energy objectives are considered

Expressing application and network adaptivity : time variations and adaptation paths

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2001.Includes bibliographical references (leaves 45-48).Existing wireless networks provide a wide variety of service capabilities. Due to the inherent nature of wireless transmissions, these services are often characterized by high error rates, variable bandwidths and delays, and unpredictable interruptions. Users and applications are somewhat adaptive in their ability to handle these variable service conditions. However applications are not completely flexible nor does the user perceived quality vary in uniform fashion with the changes in network service. By characterizing flexibility, network service variations and application behaviors can be correlated to improve the QoS provided. To this end, this thesis argues that two new concepts, adaptation paths and time constraints, are important. Adaptation paths specify the ways in which network services and traffic can or do change with time. Time constraints capture aspects of QoS requirements related to time. In particular, two time constraints are introduced. First, a Discernible Service Time (DST) captures the duration for which a level of service must or will be provided before it is changed. Second, Interrupt Time (IT) captures durations for which a particular service may be interrupted for whatever reason. To demonstrate the utility of theses constructs this thesis provides a number of examples for how these extensions can be employed in wireless networks to improve QoS.by Steven J. Bauer.S.M

Issues in evaluating tax and payment arrangements for publicly owned minerals

Many developing countries are still heavily dependent on mineral extraction to generate fiscal revenue and to earn foreign exchange. When minerals form a significant proportion of the country's asset base it is particularly important to have a framework to evaluate the adequacy of compensation schemes. Are these countries collecting enough in return for depleting their reserves? Are these countries carrying too much of the risk? This paper describes work in progress in developing such a framework. In many mineral dependent countries, the government holds the mineral rights and enters into compensation agreements with public or private firms that will extract the resources. Given the high degree of risk and uncertainty associated with mineral development, determining tax/payment arrangements is further complicated by the need to develop risk-sharing schemes between government and the resource extractors. This paper reviews these issues briefly and concludes that when objectives are not perfectly correlated it is preferable to use multiple instruments and to match each instrument to an objectives.Economic Theory&Research,Environmental Economics&Policies,Health Economics&Finance,Banks&Banking Reform,Insurance&Risk Mitigation