Aly I. El-Osery

Distributed power control in CDMA cellular systems

In wireless cellular communication, it is essential to find effective means for power control of signals received from randomly dispersed users within one cell. Effective power control will heavily impact the system capacity. Distributed power control (DPC) is a natural choice for such purposes, because, unlike centralized power control, DPC does not require extensive computational power. Distributed power control should be able to adjust the power levels of each transmitted signal using only local measurements, so that, in a reasonable time, all users will maintain the desired signal-to-interference ratio. In this paper, we review different approaches for power control, focusing on CDMA systems. We also introduce state-space methods and linear quadratic power control (LQPC) to solve the power-control problem. A simulation environment was developed to compare LQPC with earlier approaches. The results show that LQPC is more effective, and is capable of computing the desired transmission power of each mobile station in fewer iterations, as well as being able to accommodate more users in the system.

V-Lab-a virtual laboratory for autonomous agents-SLA-based learning controllers

In this paper, we present the use of stochastic learning automata (SLA) in multiagent robotics. In order to fully utilize and implement learning control algorithms in the control of multiagent robotics, an environment for simulation has to be first created. A virtual laboratory for simulation of autonomous agents, called V-Lab is described. The V-Lab architecture can incorporate various models of the environment as well as the agent being trained. A case study to demonstrate the use of SLA is presented.

Implementation of an FPGA-based aided IMU on a low-cost autonomous outdoor robot

This paper presents the implementation of real-time algorithms for an aided Inertial Navigation System (INS) on a fabric processor based field programmable gate array (FPGA). Such an approach allows for the development of a hard real-time computational architecture tailored to the specific INS requirements while still preserving flexibility. The development of a realistic simulator proved to be an important stepping stone in the deployment of the INS algorithms in addition to providing useful insight into overall system operation. The simulation supports modular code verification and validation for the embedded target. Specifically, we focus on the integration of an inertial navigation systems (INS) with a man-portable tracked MATILDA robot manufactured by Mesa Robotics. This platform has seen service in both Afghanistan and Iraq, and divides into three pieces for transportation where each piece weighs about 20 pounds.

Power Control in Ad Hoc Networks: An Overview

In this paper, a brief overview of the power control problem will be presented along with different directions in power control design. In addition, a new approach to power control design inspired from control theory will be introduced. In this approach, linear quadratic control will be utilized to determine the transmission power of each node in the network. The system states will represent the signal quality and the error between the signal-to-interference level and the desired target. The necessary modifications to the IEEE 802.11 MAC layer to incorporate the proposed power control algorithm will be described.

Transmission power management in ad hoc networks: issues and advantages

Power management is a very important aspect of ad-hoc networks. With power management capacity, throughput and battery lifetime could be increased, and latency could be reduced. But all of these advantages may be hindered depending on the power management employed and depending on the network configuration. In this paper, issues and advantages involved in the design of power control and management schemes are discussed. We also present a novel approach to power management by utilizing modern control theory to achieve the low-level power control. Simulation has shown that the new approach provides a more accurate and faster power control, than traditional power control.

A fuzzy-statistical contour model for MRI segmentation and target tracking

In this paper, a new formulation for the parametric active contour model is presented. The new formulation is based on statistical pattern recognition theory. A hybrid of kernel density estimation and fuzzy logic is used to show that active contours can be thought of as a pattern recognition problem. The proposed approach is used in two different application domains, with different performance requirements, to demonstrate its effectiveness. First, the proposed approach is used for a magnetic resonance image segmentation problem to demonstrate the segmentation accuracy. Second, the contour is used in a target tracking experiment to show its tracking capabilities.

An adaptable outdoor robotic platform: architecture, communications, and control

This paper presents a robust, easily upgradeable robotic platform for research along with its accompanying low-bandwidth and long-distance communication system. The proposed solution is a man-portable platform with easily accessible electronics bays and a communication system that uses free software, the Internet, and a cellular network. The design is made with the goal of developing multiple robotic platforms for cooperative robotic research

A learning automata based power management for ad-hoc networks

Power management is a very important aspect of ad-hoc networks. It directly impacts the network throughput among other network metrics. On the other hand, transmission power management may result in disconnected networks and increased level of collisions. In this paper, we introduce a transmission power control based on stochastic learning automata (SLA) to modify the transmission power. Based on the level of successful transmissions and the level of packet retransmissions, the SLA will modify the transmission power level either by increasing it or decreasing it. The probabilistic nature of SLA makes it a useful choice for ad-hoc networks. Using the network simulator NS, we show that using SLA for transmission power will result in an increased system bandwidth and a decrease in the collision levels.

Non-parametric expectation maximization: a learning automata approach

The famous expectation maximization technique suffers two major drawbacks. First, the number of components has to be specified apriori. Also, the expectation maximization is sensitive to initialization. In this paper, we present a new stochastic technique for estimating the mixture parameters. Parzen Window is used to estimate a discrete estimate of the PDF of the given data. Stochastic learning automata is then used to select the mixture parameters that minimize the distance between the discrete estimate of the PDF and the estimate of the expectation maximization. The validity of the proposed approach is verified using bivariate simulation data.

An unmanned ground vehicle for landmine remediation

Anti-tank (AT) landmines slow down and endanger military advances and present sizeable humanitarian problems. The remediation of these mines by direct human intervention is both dangerous and costly. The Intelligent Systems & Robotics Group (ISRG) at New Mexico Tech has provided a partial solution to this problem by developing an Unmanned Ground Vehicle (UGV) to remediate these mines without endangering human lives. This paper presents an overview of the design and operation of this UGV. Current results and future work are also described herein. To initiate the remediation process the UGV is given the GPS coordinates of previously detected landmines. Once the UGV autonomously navigates to an acceptable proximity of the landmine, a remote operator acquires control over a wireless network link using a joystick on a base station. Utilizing two cameras mounted on the UGV, the operator is able to accurately position the UGV directly over the landmine. The UGV houses a self-contained drill system equipped with its own processing resources, sensors, and actuators. The drill system deploys a neutralizing device over the landmine to neutralize it. One such device, developed by Science Applications International Corporation (SAIC), employs incendiary materials to melt through the container of the landmine and slowly burn the explosive material, thereby safely and remotely disabling the landmine.