Investment and Pricing with Spectrum Uncertainty: A Cognitive Operator's Perspective

This paper studies the optimal investment and pricing decisions of a cognitive mobile virtual network operator (C-MVNO) under spectrum supply uncertainty. Compared with a traditional MVNO who often leases spectrum via long-term contracts, a C-MVNO can acquire spectrum dynamically in short-term by both sensing the empty "spectrum holes" of licensed bands and dynamically leasing from the spectrum owner. As a result, a C-MVNO can make flexible investment and pricing decisions to match the current demands of the secondary unlicensed users. Compared to dynamic spectrum leasing, spectrum sensing is typically cheaper, but the obtained useful spectrum amount is random due to primary licensed users' stochastic traffic. The C-MVNO needs to determine the optimal amounts of spectrum sensing and leasing by evaluating the trade off between cost and uncertainty. The C-MVNO also needs to determine the optimal price to sell the spectrum to the secondary unlicensed users, taking into account wireless heterogeneity of users such as different maximum transmission power levels and channel gains. We model and analyze the interactions between the C-MVNO and secondary unlicensed users as a Stackelberg game. We show several interesting properties of the network equilibrium, including threshold structures of the optimal investment and pricing decisions, the independence of the optimal price on users' wireless characteristics, and guaranteed fair and predictable QoS among users. We prove that these properties hold for general SNR regime and general continuous distributions of sensing uncertainty. We show that spectrum sensing can significantly improve the C-MVNO's expected profit and users' payoffs.Comment: A shorter version appears in IEEE INFOCOM 2010. This version has been submitted to IEEE Transactions on Mobile Computin

Crowdsourced Live Streaming over the Cloud

Empowered by today's rich tools for media generation and distribution, and the convenient Internet access, crowdsourced streaming generalizes the single-source streaming paradigm by including massive contributors for a video channel. It calls a joint optimization along the path from crowdsourcers, through streaming servers, to the end-users to minimize the overall latency. The dynamics of the video sources, together with the globalized request demands and the high computation demand from each sourcer, make crowdsourced live streaming challenging even with powerful support from modern cloud computing. In this paper, we present a generic framework that facilitates a cost-effective cloud service for crowdsourced live streaming. Through adaptively leasing, the cloud servers can be provisioned in a fine granularity to accommodate geo-distributed video crowdsourcers. We present an optimal solution to deal with service migration among cloud instances of diverse lease prices. It also addresses the location impact to the streaming quality. To understand the performance of the proposed strategies in the realworld, we have built a prototype system running over the planetlab and the Amazon/Microsoft Cloud. Our extensive experiments demonstrate that the effectiveness of our solution in terms of deployment cost and streaming quality

Inclined Surface Locomotion Strategies for Spherical Tensegrity Robots

This paper presents a new teleoperated spherical tensegrity robot capable of performing locomotion on steep inclined surfaces. With a novel control scheme centered around the simultaneous actuation of multiple cables, the robot demonstrates robust climbing on inclined surfaces in hardware experiments and speeds significantly faster than previous spherical tensegrity models. This robot is an improvement over other iterations in the TT-series and the first tensegrity to achieve reliable locomotion on inclined surfaces of up to 24\degree. We analyze locomotion in simulation and hardware under single and multi-cable actuation, and introduce two novel multi-cable actuation policies, suited for steep incline climbing and speed, respectively. We propose compelling justifications for the increased dynamic ability of the robot and motivate development of optimization algorithms able to take advantage of the robot's increased control authority.Comment: 6 pages, 11 figures, IROS 201

Role of Space Station: The how of space industrialization

The roles of the Space Station, as an R&D facility, as part of an industrial system which support space industralization, and as a transportation node for space operations are considered. Industrial opportunities relative to these roles are identified and space station concepts responsive to these roles are discussed

Market Structure and Energy Efficiency: The Case of New Commercial Buildings

This is a report on why commercial office buildings aren’t more energy efficient. Several decades of energy efficiency programs have resulted in some gains, but overall increases in the energy efficiency of buildings have fallen far short of the 30 to 50 percent improvement that many efficiency advocates believe is possible. The purpose of this study is to consider the “why” question by empirically examining the dynamics of new commercial building markets. To do so, the authors used multiple research techniques, including qualitative field observation and interview methods that allow for a more in-depth understanding of complicated market processes. Their research focused primarily on new office buildings and centered in four regional markets: Sacramento, San Francisco, Seattle, and Portland. The authors identify key dynamics of commercial office building markets, describe how change and innovation occurs in commercial development, discuss the implications for energy efficiency, and suggest next steps

IT and telecom companies in Kista Science City, Northern Stockholm

The Kista area north of Stockholm is a symbol of Sweden’s IT and telecom sector, which has great importance for the economy and working life. The report gives a current, empirically founded description of the IT sector in Kista (including the districts Akalla and Husby), which to a high extent previously has not been available. What do the establishments in Kista look like and what are the relations between them? The management of one hundred IT and telecom establishments in Kista with up to 200 employees have answered a substantial number of survey questions about their activities, their staff and about Kista. The report is descriptive and includes a short description of Kista’s history from the ideas of a city with an integration of work, housing and services until today’s Kista Science City, the year of establishment, number and size of the IT establishments in Kista and their activities. Some results in brief are: • Most of the companies have developed during the last five to ten years. • They are to a very high degree focused on IT and telecom. The most common activity is consulting followed by production of software, R&D and commerce. • More than half of the establishments have an exchange of experiences with other companies in Kista, and almost half of them are involved in strategic cooperation within e.g. development, production and marketing. • Quite a few outsource IT activities to other companies and work as subcontractors to them, but only a limited part of the contracts are with companies in Kista. The networks are regional and international rather than local. • About a quarter cooperate with interactive media companies in Stockholm. • The managements are throughout satisfied with Kista. On all the five factors they see as most important for their operations, Kista comes out well: communications, telecom, premises, competent staff and customers. Kista also comes out well on the criterion proximity to university; although few regard this as important, which is discussed in the report. • One fifth of the employees are women and the top manager is a woman in less then ten per cent of the establishments. • The average age of employees is 38 years. • The staff is well educated, almost 70 percent have three years university education or more. Still, managements view learning on the establishment as the most important source of skills. Perhaps university education is taken for granted.

Radar altimetry systems cost analysis

This report discusses the application and cost of two types of altimeter systems (spaceborne (satellite and shuttle) and airborne) to twelve user requirements. The overall design of the systems defined to meet these requirements is predicated on an unconstrained altimetry technology; that is, any level of altimeter or supporting equipment performance is possible