Static and Dynamic Path Planning Using Incremental Heuristic Search

Path planning is an important component in any highly automated vehicle system. In this report, the general problem of path planning is considered first in partially known static environments where only static obstacles are present but the layout of the environment is changing as the agent acquires new information. Attention is then given to the problem of path planning in dynamic environments where there are moving obstacles in addition to the static ones. Specifically, a 2D car-like agent traversing in a 2D environment was considered. It was found that the traditional configuration-time space approach is unsuitable for producing trajectories consistent with the dynamic constraints of a car. A novel scheme is then suggested where the state space is 4D consisting of position, speed and time but the search is done in the 3D space composed by position and speed. Simulation tests shows that the new scheme is capable of efficiently producing trajectories respecting the dynamic constraint of a car-like agent with a bound on their optimality.Comment: Internship Repor

Self-Interference Cancellation Using Time-Domain Phase Noise Estimation in OFDM Full-Duplex Systems

In full-duplex systems, oscillator phase noise (PN) problem is considered the bottleneck challenge that may face the self-interference cancellation (SIC) stage especially when orthogonal frequency division multiplexing (OFDM) transmission scheme is deployed. Phase noise degrades the SIC performance significantly, if not mitigated before or during the SIC technique. The presence of the oscillator phase noise has different impacts on the transmitted data symbol like common phase error (CPE) and inter-carrier interference (ICI). However, phase noise can be estimated and mitigated digitally in either time or frequency domain. Through this work, we propose a novel and simple time domain self-interference (SI) phase noise estimation and mitigation technique. The proposed algorithm is inspired from Wiener filtering in time domain. Simulation results show that the proposed algorithm has a superior performance than the already-existing time-domain or frequency domain PN mitigation solutions with a noticeable reduction in the computational complexity

Multi-User Diversity with Optimal Power Allocation in Spectrum Sharing under Average Interference Power Constraint

In this paper, we investigate the performance of multi-user diversity (MUD) with optimal power allocation (OPA) in spectrum sharing (SS) under average interference power (AIP) constraint. In particular, OPA through average transmit power constraint in conjunction with the AIP constraint is assumed to maximize the ergodic secondary capacity. The solution of this problem requires the calculation of two Lagrange multipliers instead of one as obtained for the peak interference power (PIP) constraint and calculated using the well known water-filling algorithm. To this end, an algorithm based on bisection method is devised in order to calculate both Lagrange multipliers iteratively. Moreover, Rayleigh and Nakagami-$m$ fading channels with one and multiple primary users are considered to derive the required end-to-end SNR analysis. Numerical results are depicted to corroborate our performance analysis and compare it with the PIP case highlighting hence, the impact of the AIP constraint compared to the PIP constraint application

Cooperative Cognitive Relaying Under Primary and Secondary Quality of Service Satisfaction

This paper proposes a new cooperative protocol which involves cooperation between primary and secondary users. We consider a cognitive setting with one primary user and multiple secondary users. The time resource is partitioned into discrete time slots. Each time slot, a secondary user is scheduled for transmission according to time division multiple access, and the remainder of the secondary users, which we refer to as secondary relays, attempt to decode the primary packet. Afterwards, the secondary relays employ cooperative beamforming to forward the primary packet and to provide protection to the secondary destination of the secondary source scheduled for transmission from interference. We characterize the diversity-multiplexing tradeoff of the primary source under the proposed protocol. We consider certain quality of service for each user specified by its required throughput. The optimization problem is stated under such condition. It is shown that the optimization problem is linear and can be readily solved. We show that the sum of the secondary required throughputs must be less than or equal to the probability of correct packets reception.Comment: This paper was accepted in PIMRC 201

On Orthogonal Band Allocation for Multi-User Multi-Band Cognitive Radio Networks: Stability Analysis

In this work, we study the problem of band allocation of $M_s$ buffered secondary users (SUs) to $M_p$ primary bands licensed to (owned by) $M_p$ buffered primary users (PUs). The bands are assigned to SUs in an orthogonal (one-to-one) fashion such that neither band sharing nor multi-band allocations are permitted. In order to study the stability region of the secondary network, the optimization problem used to obtain the stability region's envelope (closure) is established and is shown to be a linear program which can be solved efficiently and reliably. We compare our orthogonal allocation system with two typical low-complexity and intuitive band allocation systems. In one system, each cognitive user chooses a band randomly in each time slot with some assignment probability designed such that the system maintained stable, while in the other system fixed (deterministic) band assignment is adopted throughout the lifetime of the network. We derive the stability regions of these two systems. We prove mathematically, as well as through numerical results, the advantages of our proposed orthogonal system over the other two systems.Comment: Conditional Acceptance in IEEE Transactions on Communication

Association Between Joint Hypermobility Syndrome and Developmental Coordination Disorder – A Review.

Introduction: The term joint hypermobility syndrome (JHS) was adopted after clinicians became aware of the myriad of symptoms associated with this multisystemic condition. JHS is an inherited disorder of connective tissues affecting the musculoskeletal and visceral systems which may contribute to a reduction in health related physical fitness. Pain associated with JHS may be influenced by hypermobility and biomechanical dysfunction. Biomechanical dysfunction observed in patients with JHS may be as a result of impaired motor control and in particular developmental coordination disorder (DCD). DCD (described in the literature utilising the terms clumsy child syndrome; perceptual motor dysfunction; dyspraxia) is a neurodevelopmental condition characterised by coordination difficulties affecting function. The objective of this review is to examine the association between hypermobility, JHS, motor control impairment and DCD. Methods and data sources: EMBASE, MEDLINE, CINAHL, ASSIA, PsychARTICLES, SPORTDiscus and PsycINFO from 1989 - 2009. Research articles written in English and peer reviewed were included. Results: Five research papers were identified. The studies employed a variety of methodologies and assessment tools for reporting joint hypermobility, JHS, motor delay, motor impairments and DCD. All five studies reported on children between the ages of six months and 12 years. Three out of four studies reported on association between impaired motor development, motor delay and joint hypermobility. There was no consensus as to whether motor delay, impaired motor development and joint hypermobility continued as the child matured. One study ascertained that children with JHS reported similar functional difficulties as children with DCD. Conclusion: There was a paucity of literature relating to an association between joint hypermobility, JHS, impaired motor control, motor delay and DCD in children, there was no literature pertaining to adults. This association requires further exploration if professionals are to understand, nurture and manage those reporting these associated conditions

Factors influencing branchless banking for microfinance in Sudan: Theoretical perspectives and future directions

In Sudan more than 40% live below the poverty line and getting basic financial service poses a challenge to financial institutions. Most of these unserved populations live in far-flung areas that make it difficult for microfinance institutions to reach them. But the enormous growth of mobile technology industry has created new opportunity to expand financial services to this unserved population. Branchless banking is one of the latest technologies that have been employed in different developing countries to expand financial services to the unbanked poor. Despite the potential benefits and relevance of Branchless banking to Sudan, there are still very few studies on Branchless banking in Sudan. To address this gap in the literature, this study aims to investigate the factors that are essential to the development of branchless banking in Sudan using mobile technology. This is a research-in-progress paper, the critical review of the literature so far revealed that there are essential factors for the success of branchless banking in Sudan e.g. the identification of the industry key players and their roles, the enabling regulatory environment, the infrastructure readiness and Sudanese cultural values. The paper will provide regulators and policy makers in Sudan a way forward to expedite the development of suitable Branchless banking for microfinance in Sudan