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Recent advances in dynamic spectrum sharing have led to renewed focus on the structure of regulatory games between a primary user and a secondary user of a spectrum band. The primary user has to decide to what extent it invokes the services of the regulator, and the secondary user has to decide how to operate in the spectrum band. This paper builds on a mathematical model for light-handed regulation...
The combination of emerging new communication technologies, economic growth, and current limitations on the amount of available dedicated spectrum necessitate sharing spectrum dynamically between incumbent (primary) users and opportunistic (secondary) users. This paper builds upon the seminal “spectrum jails” paradigm — a mathematical model for light-handed ex-post enforcement. Analyzing this as a...
Reachability traditionally thinks about the controllability Grammian of a system, i.e. the actuation vectors as they pass through the plant dynamics. This perspective depends on fully knowing the future plant dynamics even as we apply controls in the present, since the ability to plan is important for control.
This paper takes a step towards making practical cooperative protocols for wireless low-latency high-reliability communication. We consider the effect of finite block-length error correction codes and the main message is that the demands on the error-correcting code are different in different phases of a diversity-seeking cooperative protocol: In the first hop where messages must reach potential relays,...
Cooperative communication to extract multi-user diversity and network coding are two ideas for improving wireless protocols. These ideas can be exploited to design protocols for low-latency high-reliability communication for control. Given the high-performance constraints for this communication, it is critical, to understand how sensitive such protocols are to modeling assumptions. We examine the...
The role of information in the context of control is a deep issue. To get at this, we review Witsenhausen’s notions of information patterns for control problems. While staying in that basic framework, we then use ideas from traditional information theory as we re-examine Witsenhausen’s famous “counterexample”. In the process, we construct a family of nonlinear “quantizing” control laws that can perform...
The Internet of Things (IoT) envisions simultaneous sensing and actuation of numerous wirelessly connected devices. Emerging human-in-the-loop applications demand low-latency high-reliability communication protocols, paralleling the requirements for high-performance industrial control. This paper introduces a wireless communication protocol based on network coding that in conjunction with cooperative...
The Internet of Things (IoT) envisions simultaneous sensing and actuation of numerous wirelessly connected devices. Emerging human-in-the-loop applications demand low-latency high-reliability communication protocols, paralleling the requirements for high-performance industrial control. This paper introduces a wireless communication protocol based on network coding that in conjunction with cooperative...
This paper develops an information-theoretic understanding of side information in control systems. We build on the notion of "control capacity" — the rate at which a controller can dissipate uncertainty in a system over an actuation channel — and quantify the change in control capacity due to side information. The results build on the bit-level carry-free models that are widely used to understand...
Spectrum whitespaces and dynamic spectrum sharing have become important and interesting topics in recent years. The USA authorized the use of TV whitespaces in 2008 and the UK and Canada followed suit in early 2015. In light of the PCAST report of 2012, additional bands are being evaluated for spectrum sharing in the USA and abroad. With the increasing momentum of spectrum whitespaces, it is more...
Vector systems are fundamentally different from scalar systems since the dynamics of a vector system can both spin and stretch the system state. The magnitude and direction of control actions for multi-dimensional systems can need to be coordinated across time to achieve the desired behavior. Hence, planning for future actions is important. Consequently, system predictability, and the related ability...
This paper presents a notion of “control capacity” that gives a fundamental limit on the control of a system through an unreliable actuation channel. It tells us how fast we can reliably actively dissipate uncertainty in a system through that actuation channel. We give a computable single-letter characterization for scalar systems with memoryless stationary multiplicative actuation channels. The sense...
The Internet of Things envisions not only sensing but also actuation of numerous wirelessly connected devices. Seamless control with humans in the loop requires latencies on the order of a millisecond with very high reliabilities, paralleling the requirements for high-performance industrial control. Today's practical wireless systems cannot meet these reliability and latency requirements, forcing...
While some whitespace devices will be self-sufficient (“masters”), others will rely on help from other devices in order to access the whitespaces (“slaves”). Currently, this help is provided by a single master device. In this paper, we argue that (1) this assistance need not be provided by a single device and (2) the assisting device need not be a whitespace device. Instead, we can think of the “slave”...
Spectrum has traditionally been allocated for single uses and by now most of the “prime” spectrum has well-entrenched incumbent users. When a new service needs spectrum, there are two qualitatively distinct ways of making bandwidth available for it. A swath of incumbent users can be removed from a band, with the cleared band being reallocated for the new service. Alternatively, the new users can be...
As in portfolio theory, we can think of the value of side-information in a control system as the change in the “growth rate” due to side-information. A scalar counterexample (motivated by carry-free deterministic models) shows the value of side-information for control does not exactly parallel the value of side-information for portfolios. Mutual-information does not seem to be a bound here. The concept...
High-performance industrial control systems with tens to hundreds of sensors and actuators use wired connections between all of their components because they require low-latency, high-reliability links to maintain stability; however, the wires cause many mechanical problems that moving to wireless links would solve. No existing or proposed wireless system can achieve the latency and reliability required...
In [1]-[5], we have developed a mathematical theory of spectrum jails to enable light-handed spectrum regulation. The major result of this work is that trust can be guaranteed at certification time regardless of the technical solution for finding spectrum holes. Then, performance can improve as technology gets better. This paper is the policy-oriented case for why a new model of trust is needed in...
The GSM network is the largest network on Earth, providing vital communications service to billions of people. Yet hundreds of millions of people live outside the coverage of existing cellular providers. Recently, researchers have demonstrated a new model of cellular connectivity, community cellular, that has the potential to bring coverage to extremely rural populations. Although the total capital...
In this paper, we consider the problem of granting whitespace access to devices which have neither certified sensing capabilities nor a means of direct geolocation. These devices, called “slaves,” use a nearby “master” device to assist in determining which channels are available for secondary use. Such devices must be supported since even a “master” device which uses GPS for geolocation will need...
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