Babak Azimi-Sadjadi

Intelligent Automation, Inc.

In this demonstration, we present new capabilities of Intelligent Automation Inc. (IAI) Radio Frequency Network Emulation Simulation Tool (RFnestTM) (www.i-a-i.com/rfnest). RFnestTM is a Field Programmable Gate Array (FPGA) based network channel emulator that allows all of the channels of a full network of radio nodes to be emulated in real time, w...

We present a high fidelity cognitive radio (CR) network emulation platform for wireless system tests, measure- ments, and validation. This versatile platform provides the configurable functionalities to control and repeat realistic physical channel effects in integrated space, air, and ground networks. We combine the advantages of scalable simulati...

RFnest™ is an FPGA based network channel emulator that allows all of the channels for a full network of radio nodes to be emulated in real time, with all communication experiencing a realistic channel impulse response and correct interference. RFnest™ is the first network emulator that allows virtual simulated nodes and real RF nodes to interact an...

We study the performance of cooperative relaying using orthogonal frequency division multiplexing (OFDM) in the presence of frequency offsets due to Doppler shifts and oscillator instabilities. Through this study, several aspects of transmitter and receiver design, including channel coding, subcarrier mapping and channel estimation are brought to l...

The broadcast nature of any wireless communication network provides a natural eavesdropping and intervention capability to an adversary. Anyone with a tuned receiver within a radius that permits adequate signal to interference and noise ratio (SINR) may eavesdrop. Thus, effecting efficient key generation and renewal algorithms to ensure confidentia...

In this article, we introduce a novel link layer cooperation technique in noisy wireless networks to improve overall system throughput and reliability, and to reduce the cost of retransmission and energy consumption. Under a cluster-based network design, Chase combining (Chase, IEEE Transactions on Communications 33(5):385–393, 1985) is used togeth...

We address the shortage of available software frameworks for distributed control systems/robotics and describe a novel agent-based software architecture simplifying the development, testing, and deployment of distributed controllers. Our distributed control framework (DCF) provides extensive support for robot team coordination and management, a plu...

In this paper we present an agent-based distributed control framework for modeling, simulation, test and execution of distributed controllers for large autonomous unmanned vehicle teams, and a hybrid level set-based algorithm for boundary tracking using a class of unmanned ground vehicle teams. The framework provide an effective way to test and val...

The capacity of wireless ad hoc networks is constrained by the interference caused by the neighboring nodes. Gupta and Kumar have shown that the throughput for such networks is only Θ $(\frac{W}{\sqrt{n}})$ bits per second per node in a unit area domain when omnidirectional antennas are used [1]. In this paper we investigate the capacity of ad hoc...

The broadcast nature of a wireless link provides a natural eavesdropping and intervention capability to an adversary. Thus, securing a wireless link is essential to the security of a wireless network, and key generation algorithms are nec- essary for securing wireless links. However, traditional key agreement algorithms can be very costly in many s...

In a wireless LAN, the throughput is essentially important for multimedia applications due to their high bit rate requirement. In this paper, we propose two link layer error protection schemes that improve the effective throughout of wireless networks. Error control is applied to the packet header and packet payload separately. The network intermed...

Multimedia applications have different Quality of Service (QoS) requirements. In a multi-hop network, the throughput is essentially important for real-time applications due to their high bit rate requirement. In the wireless networks, error comes from fading, noise, or interference. Link layer error control will have impact on the end-to- end throu...

In this paper, we introduce for the first time particle filtering for an exponential family of densities. We prove that under certain conditions the approximated conditional density of the state converges to the true conditional density. In the realistic setting where the conditional density does not lie in an exponential family but stays close to...

In this paper we consider a system whose controller is directly connected to the actuators and receives the observation data from the sensors through a network. Because of packet loss in the network, the controller does not always have access to the observation data. For this networked control system we prove that if the covariance of the error of...

We present a change detection method for nonlinear stochastic systems based on particle filtering. We assume that the parameters of the system before and after change are known. The statistic for this method is chosen in such a way that it can be calculated recursively while the computational complexity of the method remains constant with respect t...

We present a change detection method for nonlinear stochastic systems based on particle filtering. We assume that the parameters of the system before and after change are known. The statistic for this method is chosen in such a way that it can be calculated recursively while the computational complexity of the method remains constant with respect t...

This paper presents a cooperative multi-input-multi-output (MIMO) diversity scheme for CDMA wireless multihop networks. None of the nodes have multiple antennas, allowing them to be small and lightweight. Using cooperative clusters of network nodes to relay information to its destination, the scheme both increases the effective rates and extends th...

In this paper we present a general framework for networked control systems, where all components are assumed to be connected through a communication network. We use the uncertainty threshold principle to show that under certain conditions there is a rate for dropped packets for which an undisturbed networked control system is mean square stable.

In this paper we propose a method in CDMA wireless multi-hop networks which groups transmission nodes into cooperative clusters coupled with RAKE receivers at each receiving node to reduce the total power expenditure of transmitting nodes. With this method cooperative nodes in each cluster act as a distributed nonlinear antenna array which, with an...

We present a change detection method for nonlinear stochastic systems based on projection particle filtering. The statistic for this method is chosen in such a way that it can be calculated recursively while the computational complexity of the method remains constant with respect to time. We present some simulation results that show the advantages...

Using carrier phase measurements enables the differential GPS to reach centimeter level accuracy. A phase lock loop cannot measure the full cycle part of the carrier phase. This unmeasured part is called integer ambiguity that requires to be resolved through other means. In this paper we present a new integer ambiguity resolution method. In this me...

We address the problem of nonlinear filtering in the presence of integer uncertainty. This setup is specially important for the case of differential GPS with carrier phase measurements. In simulation results we show that particle filtering is capable of resolving integer ambiguity in the given nonlinear setup. Motivated by these results we introduc...

In a multi-hop network, the throughput is essentially important for real-time applications due to their high bit rate requirement. We investigate the performance of multimedia applications in wireless networks and the impact of various error control protocols. In particular, we propose a two stage error control scheme that improves the effective th...

Abstract – IEEE 802.15.4 shares its frequency band with many existing technologies such as Bluetooth, IEEE 802.11, microwave ovens and other devices that use the same ISM bandwidth. The interference caused by these technologies can degrade the performance of an IEEE 802.15.4 based wireless network. In this paper we study such degrading effects on a...