Is re-farming the answer to the spectrum shortage conundrum?

Radio spectrum has become one of the engines of economic growth. However, rapid technological change, ever increasing demands for new wireless services and the nature of spectrum as a scarce resource necessitate an urgent re-examination of issues such as congestion and interference. This paper argues that the traditional administrative spectrum management approach is unlikely to overcome these issues, thereby resulting in growing technical and economic inefficiencies. As countries review their spectrum policies - a process that is generically referred to as radio spectrum policy reform - to counter these inefficiencies, modifications to the radio frequency allocations and assignments are beginning to be implemented by way of radio spectrum re-farming? This phenomenon forms the subject matter of this paper

Decomposition Methods in Column Generation and Data-Driven Stochastic Optimization

In this thesis, we are focused on tackling large-scale problems arising in two-stage stochastic optimization and the related Dantzig-Wolfe decomposition. We start with a deterministic setting, where we consider linear programs with a block-structure, but data cannot be stored centrally due to privacy concerns or decentralized storage of large datasets. The larger portion of the thesis is dedicated to the stochastic setting, where we study two-stage distributionally robust optimization under the Wasserstein ambiguity set to tackle problems with limited data. In Chapter 2, joint work with Shabbir Ahmed, we propose a fully distributed Dantzig-Wolfe decomposition (DWD) algorithm using the Alternating Direction Method of Multipliers (ADMM) method. DWD is a classical algorithm used to solve large-scale linear programs whose constraint matrix is a set of independent blocks coupled with a set of linking rows but requires to solve a master problem centrally, which can be undesirable or infeasible in certain cases due to privacy concerns or decentralized storage of data. To this end, we develop a consensus-based Dantzig-Wolfe decomposition algorithm where the master problem is solved in a distributed fashion. We detail the computational and algorithmic challenges of our method, provide bounds on the optimality gap and feasibility violation, and perform extensive computational experiments on instances of the cutting stock problem and synthetic instances using a Message Passing Interface (MPI) implementation, where we obtain high-quality solutions in reasonable time. In Chapter 3 and 4, we turn our focus to stochastic optimization, specifically applications where data is scarce and the underlying probability distribution is difficult to estimate. Chapter 3 is joint work with Anirudh Subramanyam and Kibaek Kim. Here, we consider two-stage conic DRO under the Wasserstein ambiguity set with zero-one uncertainties. We are motivated by problems arising in network optimization, where binary random variables represent failures of network components. We are interested in applications where such failures are rare and have a high impact, making it difficult to estimate failure probabilities. By using ideas from bilinear programming and penalty methods, we provide tractable approximations of our two-stage DRO model which can be iteratively improved using lift-and-project techniques. We illustrate the computational and out-of-sample performance of our method on the optimal power flow problem with random transmission line failures and a multi-commodity network design problem with random node failures. In Chapter 4, joint work with Alejandro Toriello and George Nemhauser, we study a two-stage model which arises in natural disaster management applications, where the first stage is a facility location problem, deciding where to open facilities and pre-allocate resources, and the second stage is a fixed-charge transportation problem, routing resources to affected areas after a disaster. We solve a two-stage DRO model under the Wasserstein set to deal with the lack of available data. The presence of binary variables in the second stage significantly complicates the problem. We develop an efficient column-and-constraint generation algorithm by leveraging the structure of our support set and second-stage value function, and show our results extend to the case where the second stage is a fixed-charge network flow problem. We provide a detailed discussion on our implementation, and end the chapter with computational experiments on synthetic instances and a case study of hurricane threats on the coastal states of the United States. We end the thesis with concluding remarks and potential directions for future research.Ph.D

The ITU IMT-2020 Standardization: Lessons from 5G and Future Perspectives for 6G

The evaluation of candidate International Mobile Telecommunications-2020 (IMT-2020) radio interfaces ended in February 2021, with three technologies being approved while another two were granted additional time to demonstrate their suitability. This marks a useful milestone at which the International Mobile Telecommunications (IMT) standardization process can be evaluated, and its implications for 6G explored. We argue that the relationship between IMT standardization and identification is increasingly problematic, with identification requiring the refarming of spectrum already allocated to other services. Furthermore, as standardization is largely done outside of the International Telecommunication Union (ITU), being part of IMT is largely a way to obtain more spectrum. While these developments question the value of the existing approach, we argue that changes are necessary to the IMT standardization processes given the value to be gained from a single global mobile standard

Clinical and electrophysiological study of peripheral and central neuromuscular changes in connective tissue diseases in children

AbstractIntroductionChildren with juvenile connective tissue diseases (JCTDs) may have a wide variety of clinical features ranging from fever or a simple arthritis to complex multisystem autoimmune diseases.Aim of the workTo study clinical and electrophysiological peripheral and central neuromuscular changes in children with connective tissue diseases.Patients and methodsThirty children with different JCTDs were enrolled. Clinical and neurological examination and laboratory investigations were done. Electrophysiological evaluation was performed and included: peripheral nerve conduction studies, late responses, somatosensory evoked potential and electromyography.ResultsTwenty patients had juvenile idiopathic arthritis (JIA) (66.7%), 8 patients had juvenile systemic lupus erythematosus (JSLE) (26.7%), one patient had juvenile systemic sclerosis (JSScl), and one patient had juvenile overlap syndrome (JSScl and polymyositis). Clinical neurologic abnormalities were present in 3 patients (ulnar neuropathy, median neuropathy and polymyositis). Electrophysiological abnormalities were detected in 18 patients (clinical in 3 and subclinical in 15 patients) and included ulnar entrapment neuropathy, median axonal neuropathy, demyelinating sensory motor polyneuropathy, deep peroneal nerve entrapment at the ankle (anterior tarsal tunnel syndrome), prolonged posterior tibial somatosensory evoked potential latency and prolonged H reflex latency not explained by peripheral neuropathy, increased H/M ratio and myopathic motor units. The most common electrophysiological abnormalities were present in patients with JSLE.ConclusionClinical neurological abnormalities are not common in JCTDs whereas subclinical neurological abnormalities are common findings. Juvenile systemic lupus erythematosus had the most common abnormalities among JCTDs. Polyneuropathy in JIA is commonly of demyelinating type. Entrapment neuropathy is less frequent than in adults

World radiocommunication conference 12 : implications for the spectrum eco-system

Spectrum allocation is once more a key issue facing the global telecommunications industry. Largely overlooked in current debates, however, is the World Radiocommunication Conference (WRC). Decisions taken by WRC shape the future roadmap of the telecommunications industry, not least because it has the ability to shape the global spectrum allocation framework. In the debates of WRC-12 it is possible to identify three main issues: enhancement of the international spectrum regulatory framework, regulatory measures required to introduce Cognitive Radio Systems (CRS) technologies; and, additional spectrum allocation to mobile service. WRC-12 eventually decided not to change the current international radio regulations with regard to the first two issues and agreed to the third issue. The main implications of WRC-12 on the spectrum ecosystem are that most of actors are not in support of the concept of spectrum flexibility associated with trading and that the concept of spectrum open access is not under consideration. This is explained by the observation that spectrum trading and spectrum commons weaken state control over spectrum and challenge the main principles and norms of the international spectrum management regime. In addition, the mobile allocation issue has shown the lack of conformity with the main rules of the regime: regional spectrum allocation in the International Telecommunication Union (ITU) three regions, and the resistance to the slow decision making procedures. In conclusion, while the rules and decision-making procedures of the international spectrum management regime were challenged in the WRC-12, the main principles and norms are still accepted by the majority of countries

Exploring the interaction between the international radio spectrum management regime and national radio spectrum management policies

This thesis was previously held under moratorium from 1st December 2016 until 1st December 2020.National spectrum management policy is once more a key issue facing the global telecommunications industry in order to meet the rapid growth in wireless services and the increasing demand for mobile broadband. Three approaches are usually suggested to overcome the deficiencies of the command and control approach to spectrum management: spectrum markets, spectrum commons, and spectrum easements. Meanwhile, while a few countries have reformed or planned to reform their national policies, in most of the world, especially in the developing countries, radio spectrum is managed along the lines of traditional government administration due to different factors. Largely overlooked in current debates, however, is the influence of the international spectrum management regime on national policy reform. To address such influence, this thesis has examined the main research question 'How do the international radio spectrum management regime and national radio spectrum management policies interact?' With a focus on the cases of Egypt and UAE, this research has examined the research question regarding three main concepts, radio communication service allocation flexibility, technology neutrality, and opportunistic access in the TV White Spaces (TVWS), which are considered as main elements of the three alternative approaches to command and control. Data was collected through semi-structured interviews with main national and international actors. The main finding of the thesis is that the international spectrum management regime does not prevent adopting radiocommunication service allocation flexibility, technology neutrality, or opportunistic access in the TVWS. However, there are different elements of flexibility and restriction that have an influence on regulators' flexibility regarding radiocommunication service allocation, regulators' tendency towards technology neutrality, and deployment of opportunistic access in the TVWS. These elements are dependent on the country's geographical position, country's relationship with neighbouring countries, size of country market, being advanced in technology, interpretation of the international regulations, and national telecommunication market status.National spectrum management policy is once more a key issue facing the global telecommunications industry in order to meet the rapid growth in wireless services and the increasing demand for mobile broadband. Three approaches are usually suggested to overcome the deficiencies of the command and control approach to spectrum management: spectrum markets, spectrum commons, and spectrum easements. Meanwhile, while a few countries have reformed or planned to reform their national policies, in most of the world, especially in the developing countries, radio spectrum is managed along the lines of traditional government administration due to different factors. Largely overlooked in current debates, however, is the influence of the international spectrum management regime on national policy reform. To address such influence, this thesis has examined the main research question 'How do the international radio spectrum management regime and national radio spectrum management policies interact?' With a focus on the cases of Egypt and UAE, this research has examined the research question regarding three main concepts, radio communication service allocation flexibility, technology neutrality, and opportunistic access in the TV White Spaces (TVWS), which are considered as main elements of the three alternative approaches to command and control. Data was collected through semi-structured interviews with main national and international actors. The main finding of the thesis is that the international spectrum management regime does not prevent adopting radiocommunication service allocation flexibility, technology neutrality, or opportunistic access in the TVWS. However, there are different elements of flexibility and restriction that have an influence on regulators' flexibility regarding radiocommunication service allocation, regulators' tendency towards technology neutrality, and deployment of opportunistic access in the TVWS. These elements are dependent on the country's geographical position, country's relationship with neighbouring countries, size of country market, being advanced in technology, interpretation of the international regulations, and national telecommunication market status

The APT Frequency Arrangement in the 700 MHz: Reflections on the International Spectrum Management Regime

Following WRC-12, discussions have emerged with regard to the frequency arrangements in the 700 MHz band, out of band emissions (OOBE) of the mobile terminals below 694 MHz considering the allocation of the 694-790 MHz band to the mobile service. These discussions have shown that there is a tendency to partially harmonise with the APT plan and to adopt APT OOBE values. This reflects the emerging approach of countries in Regions 1 and 2 that are aligning themselves with Region 3 to lower the cost of end user equipment. Countries such as Australia and New Zealand are leading the discussion in Region 3. The 700 MHz issue has revealed that the ITU-R decision making procedures are mostly based upon consensus with the possibility of few countries blocking the discussion. Moreover, it suggests that there is a need to revise the current ITU-R structure of three regions

Allocating spectrum : towards a commons future

Spectrum divide is a consequence of the current spectrum management framework which is locked into a paradigm that is based on assigning spectrum exclusively to a number of operators. This regulatory gridlock is due to resistance from current institutional framework, decision making political economy, and misconception of commons. Industrial, Scientific and Medical (ISM) applications, International Telecommunication Union (ITU) primary allocation for mobile service in the 5 GHz for the implementation of WLAN applications, and operation of Cognitive Radio Systems (CRS) in the TV white spaces have initiated changes to the current framework. The driving forces for CRS deployment are ITU indirect support, pressure on regulators to face the growth in data demand, and benefits to the industry. On the other hand, the undermining forces are the ITU concerns, regulators' constrains, broadcasting deployment, and manufacturing issues. This paper argues that the CRS trigger has initiated a new wave of changes within the current spectrum management framework towards spectrum commons where DSA is enabled in other services' spectrum bands rather than broadcasting. The new spectrum management paradigm would accommodate a new kind of secondary operators that deploy CRS to dynamically access the licensees' spectrum. However, it would be difficult for this new paradigm to evolve towards the spectrum commons paradigm. This is due to the structure of the current spectrum management framework which is in favour of regulators and operators