Energy-Efficient Power Control for Contention-Based Synchronization in OFDMA Systems with Discrete Powers and Limited Feedback

This work derives a distributed and iterative algorithm by which mobile terminals can selfishly control their transmit powers during the synchronization procedure specified by the IEEE 802.16m and the 3GPP-LTE standards for orthogonal frequency-division multiple-access technologies. The proposed solution aims at maximizing the energy efficiency of the network and is derived on the basis of a finite noncooperative game in which the players have discrete action sets of transmit powers. The set of Nash equilibria of the game is investigated, and a distributed power control algorithm is proposed to achieve synchronization in an energy-efficient manner under the assumption that the feedback from the base station is limited. Numerical results show that the proposed solution improves the energy efficiency as well as the timing estimation accuracy of the network compared to existing alternatives, while requiring a reasonable amount of information to be exchanged on the return channel

StrawMAN: Making Sudden Traffic Surges Graceful in Low-Power Wireless Networks

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Conflict in Organizations

{Excerpt} Michael Cohen, James March, and Johan Olsen9 have developed an influential, agent-based representation of organizational decision-making processes. They submit that organizations are—at least in part and part of the time—distinguished by three general properties: (i) problematic preferences, (ii) unclear technology, and (iii) fluid participation. Citing, “Although organizations can often be viewed conveniently as vehicles for solving well-defined problems or structures within which conflict is resolved through bargaining, they also provide sets of procedures through which participants arrive at an interpretation of what they are doing and what they have done while in the process of doing it. From this point of view, an organization is a collection of choices looking for problems, issues and feelings looking for decision situations in which they might be aired, solutions looking for issues to which they might be the answer, and decision makers looking for work.” Decision opportunities characterized by problematic preferences, unclear technology, and fluid participation, viz., ambiguous stimuli, generate three possible outcomes, each driven by the energy it requires within the confines of organizational structure. These outcomes, whose meaning changes over time, are resolution, oversight, and flight. Significantly, resolution of problems as a style for making decisions is not the most common; in its place, decision making by flight or oversight is the feature. Is it any wonder then that the relatively complicated intermeshing of elements does not enable organizations to resolve problems as often as their mandates demand

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

Design of State-based Schedulers for a Network of Control Loops

For a closed-loop system, which has a contention-based multiple access network on its sensor link, the Medium Access Controller (MAC) may discard some packets when the traffic on the link is high. We use a local state-based scheduler to select a few critical data packets to send to the MAC. In this paper, we analyze the impact of such a scheduler on the closed-loop system in the presence of traffic, and show that there is a dual effect with state-based scheduling. In general, this makes the optimal scheduler and controller hard to find. However, by removing past controls from the scheduling criterion, we find that certainty equivalence holds. This condition is related to the classical result of Bar-Shalom and Tse, and it leads to the design of a scheduler with a certainty equivalent controller. This design, however, does not result in an equivalent system to the original problem, in the sense of Witsenhausen. Computing the estimate is difficult, but can be simplified by introducing a symmetry constraint on the scheduler. Based on these findings, we propose a dual predictor architecture for the closed-loop system, which ensures separation between scheduler, observer and controller. We present an example of this architecture, which illustrates a network-aware event-triggering mechanism.Comment: 17 pages, technical repor

Towards a new European Global Security Strategy: challenges and Opportunities

This report briefly examines the interplay between the European security strategic vision and capabilities, its institutional architecture and policy implementation practices, with a particular focus on the EU consular affairs, EU democracy promotion and EU engagement in frozen conflicts under the Neighbourhood Policy (Appendices 1-3). This report contends that in order for the EU to develop an effective and sustainable global security strategy, it first, has to reconcile the vision of its strategic priorities within its inter- and intra-institutional settings. Second, a serious effort is required to develop an integrated view on European security, which does not only focus on the internal dimensions of the EU Security strategy (capabilities), but also equally draws on its external aspects - a genuinely inclusive approach that would blur internal and external dimensions of security. For this to succeed a deeper understanding of a partnership-building process (especially of strategic partnership) is needed. Finally, while legitimation of the new security vision is essential within the EU, a greater emphasis should be placed on its external environment, which must not only include a cross-cutting approach to multiple policy instruments as suggested by the EEAs, but more essentially, their connection with the interests and needs of third parties. Case-studies in appendices elaborate further on some specific aspects of the EU security within the eastern neighbourhood context

The review of a design practice learning project to pilot heightened social responsibility and engagement

This paper describes the review of a design project devised to pilot a student community learning experience at a heightened level of social responsibility. There is evidence around the world that degree level programmes are beginning this process, albeit through initial discussions (Swan, 2000). The project involved students in the use of open-space technology to promote creative team working and reflective practice reporting on the design project. The review involved a programme of qualitative research into the evidence and outputs created by the students and staff and compared these with interviews with the; participants, industrial sponsor, independent academic staff and professional designers. It was not possible to determine in the review whether the project had led to a greater level of creativity, but those involved described it as a profoundly creative experience. The findings showed that the project engendered truly effective teamworking, complete consensus to solutions amongst the students and a heightened sensitivity to societal issues. The review makes recommendations for the future development of this form of design practice learning at appropriate levels of study