CNRG Research Projects


Wireless networks research

Increasingly we have come to depend on wireless networks for internet access.  Unfortunately, existing wireless networks are almost exclusively confined to single hop access, as provided by cellular telephony or wireless LANs. Multi-hop wireless networks can be deployed; however, current protocols typically result in extremely poor performance for even moderate sized networks. Our research in the area of wireless networks attempts to bridge the gap between wireless networks and the wired internet, by addressing issues in the control and management of wireless networks, including mobile ad hoc networks, sensor networks, and wireless mesh networks.  Our goal is to develop develop architectures,  protocols, and control algorithms for  providing efficient and reliable wireless networking.  Our projects include fundamental aspects of network control, robust wireless network design, as well as the design of practical practical network control algorithms for  routing, scheduling and flow control.

Effective Control of Wireless Networks

Wireless Mesh Networks (WMNs) have emerged as a solution for providing last-mile Internet access. By exploiting advanced communication technologies such as adaptive modulation and coding, MIMO, OFDM, and Software Radio, WMNs can achieve access rates that are comparable to those achieved by wired access technologies. However, hindering their success is our relative lack of understanding of how to effectively control wireless networks; especially in the context of advanced physical layer technologies, realistic models for channel interference, and distributed operation. The goal of this project is to develop effective and practical network control algorithms that make efficient use of wireless resources through joint topology adaptation, network layer routing, MAC layer scheduling, and physical layer power, channel, and rate control.

A Migration Approach to Optimal Network Control

Our new NSF project introduces a novel architectural paradigm for wireless network control, whereby control algorithms are designed to operate in networks with both new and legacy nodes.  This new paradigm allows optimal control algorithms to be incrementally deployed alongside existing schemes, thus providing a migration path for new control algorithms, and the promise of dramatic improvement in network performance.  -more-

Toward Reducing Control Overhead in Wireless Networks

Network control mechanisms, such as scheduling, routing, and flow control, ensure effective data transport in a communication network, but also require the exchange of network state information, such as channel conditions and queue-length information, which amounts to “control overhead”.  The project investigates the tradeoffs between the rate of sending such control information, and the ability to effectively control the network in terms of performance metrics such as throughput, stability, delay and network utility.  The project takes a two-pronged approach:  First, a rate-distortion framework is being developed for understanding the impact of degraded network state information on network performance.  Second, mechanisms are being developed for reducing the amount of control overhead and the impact of these mechanisms on network performance is being investigated. The project develops a fundamental understanding of the requirements for protocol overhead, which will lead to more efficient network control policies, with reduced overheads.-more-

Protection and restoration in wireless mesh networks

Most previous work on routing in ad hoc networks has focused almost entirely on the problem of route discovery. Little, if any, attention has been paid to the problem of reliable communications in a mobile network. In a network this is often accomplished by providing "backup" routes. However, recovery using backup routes in ad hoc networks is very different from a static fiber networks due to the high degree of mobility that results in rapid topology changes. This project will develop efficient recovery mechanisms in a mobile ad hoc environment. -more-

Ultra-low latency and High Reliability for Wireless IoT

The goal of this project is to develop a new framework for supporting ultra-low latency and high reliability network services for emerging Internet-of-Things applications.  These emerging applications often impose stringent requirements on both latency and reliability that cannot be met with existing techniques.  The main idea behind this project is that latency and reliability are inherently coupled and must be addressed not just at the physical layer but also at higher network layers.  Our comprehensive research agenda addresses latency and reliability at various time scales, ranging from packet time scale and MAC layer scheduling to network deployment and the economics of their services. .-more-

Optimizing Information Freshness in Wireless Networks

Future Internet-of-Things (IoT) applications will increasingly rely on the exchange of delay sensitive information for monitoring and control.   Application domains such as autonomous vehicles, command and control systems, industrial control, virtual reality, and sensor networks, heavily rely upon the distribution of time-critical information.  Age of Information (AoI) is a recently proposed performance metric that captures the freshness of the information from the perspective of the application.  AoI measures the time that elapsed from the moment that the most recently received packet was generated to the present time.-more-


Network Control In Adversarial Environments

This project introduces a novel paradigm for wireless network control, whereby control algorithms are designed to operate effectively in networks with uncooperative or adversarial users.   Recent growth in mobile and media-rich applications has greatly increased the demand for wireless capacity.  Network control algorithms for flow control, routing, and scheduling have the potential to significantly improve performance.  However, these algorithms were designed under idealized assumptions, and cannot operate effectively in heterogeneous environments that includes uncooperative or even malicious users.-more-


RINGS: Enabling Wireless Edge-cloud Services via Autonomous Resource Allocation and Robust Physical Layer Technologies

Wireless technology has evolved at a remarkable rate, with data rates increasing by four orders of magnitude over the past twenty years.   New wireless communication technologies such as millimeter-wave (mmWave), and full-duplex, along with the emergence of edge-cloud computing will enable additional improvements, ultimately exceeding one giga-bits-per-second data rates and sub-millisecond delays.  This project will develop network control algorithms that leverage these emerging wireless technologies to enable robust and resilient next generation of wireless networks and usher in novel applications, such as smart cities, connected vehicles, virtual reality,  telemedicine, and advanced manufacturing.  -more-


RINGS: Robust and Resilient Wireless Networks using Next Generation Spectrum

Next generation (NextG) wireless networks will likely operate in an environment involving extensive sharing of underlying infrastructure and spectrum. In addition, many NextG services may be provided by over-the-top (OTT) providers who utilize multiple networks of shared spectrum and infrastructure to provide services to end users. These trends raise new challenges in addressing how resources are effectively shared within a network and how OTT service providers can effectively manage resources across different shared networks. These challenges are particularly acute when attempting to offer services that have stringent Quality of Service (QoS) requirements, e.g., in terms of latency and reliability, and so require a high level of robustness. This project lays out a research plan to address these questions. -more-


Optical Networks research

Over the past decade the growth in the use and capabilities of communication networks has transformed the way we live and work. As we progress further into the information age, the reliance on networking will increase. With the expected explosive growth in data traffic, networks will be strained in terms of both transport and processing requirements. Wavelength Division Multiplexing (WDM) is emerging as a dominant technology for use in backbone and access networks. With WDM, the capacity of a fiber is significantly increased by allowing simultaneous transmission on multiple wavelengths (channels), each operating at the maximum electronic rate. Systems with between 40 and 80 wavelengths are presently being deployed for point-to-point transmission. With tens of wavelengths per fiber and transmission rates of up to 10 Gbps per wavelength, capacities that approach a Tera-bit per second can be achieved.  Our research in the area of optical networks include survivable network design, access network architecture, and mechanisms for optical bypass of the electronic layers.

Mechanisms for optical bypass  

While WDM systems are likely to meet future transport demands, electronically processing all of the traffic at network nodes will present a significant bottleneck. Fortunately, it is not necessary to electronically process all traffic entering and leaving each node. For example, much of the traffic passing through a node is neither sourced at that node nor destined to that node. To reduce the amount of traffic that must be electronically processed at intermediate nodes, future WDM systems will employ WDM Add/Drop multiplexers (WADMs) and cross-connects, that allow each wavelength to either be dropped and electronically processed at the node or to optically bypass the node's electronics. Our research in this area is focused on developing mechanisms for providing optical bypass to the electronic layer thereby reducing the size and cost of electronic switches and routers in the network. These mechanisms include traffic grooming of low rate streams, logical topology reconfiguration, and optical flow switching.

Cross-Layer Survivability

Modern communication networks are constructed using a layered approach, with one or more electronic layers (e.g., IP, ATM, SONET) built on top of an optical fiber network. This multitude of layers is used in order to simplify network design and operations and to enable efficient sharing of network resources. However, this layering also gives rise to certain inefficiencies and interoperability issues.  Networks often rely on the electronic layers to provide most protection and restoration services. However, in a layered network, the protection mechanisms provided at the electronic layer may not be robust in the face of failures in the underlying optical layer. For example, SONET networks typically provide protection against single link failures using a ring network architecture, and protection in general “mesh” networks (e.g., ATM, WDM) is typically provided using disjoint paths. However, even electronic topologies that are designed to be tolerant of single link failures, once they are embedded on the physical (e.g., fiber) topology, may no longer be survivable to single physical (fiber) link failures. This is because the failure of a single fiber link can lead to the failure of multiple links in the electronic topology, which may subsequently leave the electronic topology disconnected. Thus, network survivability mechanisms often cannot provide their claimed level of protection and restoration, when embedded on a physical topology. The goal of this project is to develop a fundamental theory for understanding cross-layer survivability, and mechanisms for providing survivability in layered networks. -more-


Space Networks Research

While the field of communications and networks is rapidly advancing due to the increased popularity of the Internet, space communication systems are at a much more immature state of development. Certain attributes of the satellite channels make techniques previously developed for terrestrial networks inefficient or entirely unsuitable. For example, satellite systems often have longer propagation delays and higher bit error rates than their terrestrial counterparts; and the open air interface for satellite channels lends itself to the concept of dynamic sharing of resources.  This gives rise to a range of problems including:  Resource allocation (such as power and bandwidth), media access control,  system management, dynamic routing in the presence of changing topologies and fluctuating loads, and interconnection with terrestrial and wireless networks.  Of particular interest is the design of architectures and protocols for heterogeneous networks that include both space and terrestrial segments, which  gives rise to a range of issues including: Space/ground network architectures, the design of efficient end-to-end protocols, quality of service assurance and the design of efficient interfaces between the ground and space portions of the network.