Control Aware Radio Resource Allocation in Low Latency Wireless Control Systems

We consider the problem of allocating radio resources over wireless communication links to control a series of independent wireless control systems. Low-latency transmissions are necessary in enabling time-sensitive control systems to operate over wireless links with high reliability. Achieving fast data rates over wireless links thus comes at the cost of reliability in the form of high packet error rates compared to wired links due to channel noise and interference. However, the effect of the communication link errors on the control system performance depends dynamically on the control system state. We propose a novel control-communication co-design approach to the low-latency resource allocation problem. We incorporate control and channel state information to make scheduling decisions over time on frequency, bandwidth and data rates across the next-generation Wi-Fi based wireless communication links that close the control loops. Control systems that are closer to instability or further from a desired range in a given control cycle are given higher packet delivery rate targets to meet. Rather than a simple priority ranking, we derive precise packet error rate targets for each system needed to satisfy stability targets and make scheduling decisions to meet such targets while reducing total transmission time. The resulting Control-Aware Low Latency Scheduling (CALLS) method is tested in numerous simulation experiments that demonstrate its effectiveness in meeting control-based goals under tight latency constraints relative to control-agnostic scheduling

Connectivity in a Multi-radio, Multi-channel Heterogeneous Ad Hoc Network

Abstract. Future wireless networks are expected to integrate heterogeneous devices equipped with multiple radios and different characteristics. Nodes equipped with a single communication interface will co-exist with nodes equipped with multiple radios that can transmit and receive simultaneously. Therefore, it is important to understand how these heterogeneous radios can affect connectivity and overall multihop network performance. Maintaining connectivity in ad hoc networks has been a major challenge and many complex topology control algorithms have been investigated. In this paper, we study the connectivity of a heterogeneous ad hoc network. We consider two types of nodes: nodes equipped with a single communication interface with communication range r, and Dual-Mode (DM) nodes, equipped with two communication interfaces with two different communication ranges r and rf, respectively, where rf>r. We assume the radios in the DM nodes operate in two different channels. We provide a theoretical analysis of connectivity in a linear network and we present simulation results for the two-dimensional case that show the impact of DM nodes on connectivity, broadcast latency and robustness in static and mobile scenarios. 1

Spectrum sensing for dynamic spectrum access of TV bands

Abstract – In this paper we address the issue of spectrum sensing in cognitive radio based wireless networks. Spectrum sensing is the key enabler for dynamic spectrum access as it can allow secondary networks to reuse spectrum without causing harmful interference to primary users. Here we propose a set of integrated medium access control (MAC) and physical layer (PHY) spectrum sensing techniques that provide reliable access to television (TV) bands. At the MAC level, we propose a two-stage spectrum sensing that guarantees timely detection of incumbents while meeting the quality of service (QoS) requirements of secondary users. At the PHY level, we introduce FFT-based pilot energy and location detection schemes that can detect a TV signal on a TV channel at levels as low as-116 dBm. We have evaluated these schemes through simulation and prototyping and show their effectiveness, reliability, and efficiency. These mechanisms are also part of the current IEEE 802.22 draft standard which is based on cognitive radio technology

D.: Exploiting the Small-World Effect to Increase Connectivity in Wireless Ad hoc Networks

Abstract. This paper investigates how the small world concept can be applied in the context of wireless ad hoc networks. Different from wireless ad hoc networks, small world networks have small characteristic path lengths and are highly clustered. This path length reduction is caused by long-range edges between randomly selected nodes. However, in a wireless ad hoc network there are no such long-range connections. Then, we propose to use a fraction of nodes in the network equipped with two radios with different transmission ranges in order to introduce the long-range shortcuts. We analyze the system from a percolation perspective and show that a small fraction of these “special nodes ” can improve connectivity in a significant way. We also study the effects of the special nodes on the process of information diffusion and on network robustness.

Advances in Wireless Communication and Networking for Cooperating Autonomous Systems

International audienc

Joint Resource Scheduling for AMR Navigation Over Wireless Edge Networks

The future of autonomous systems will rely on the usage of wireless time-sensitive networks to connect mobile cyberphysical systems, such as Autonomous Mobile Robots (AMRs), to Edge compute platforms to offload computationally intensive workloads necessary to complete tasks. In the case of AMRs, due to their mobility, the offloading of expensive processes such as localization and tracking methods to the Edge computing infrastructure must also be done over dynamic wireless networks. In larger scale systems, the network and compute resource requirements can quickly become prohibitively large due to network traffic and heavy workloads and tight deadline requirements for proper execution of time-critical tasks. In this paper, we formulate the problem of jointly allocating network and compute resources for time sensitive systems as the state of the wireless channel changes over time. By characterizing a compute model for AMR workloads, we further demonstrate how the network and compute scheduling decisions can be serialized, thus making the optimal scheduling problem significantly more tractable, via the incorporation of a compute-utility aware network cost function. Simulation results of AMR systems in a Wi-Fi network demonstrate substantial gains over baseline scheduling methods in total resource efficiency