Mohammed Al-Rawi

Genetic algorithm matched filter optimization for automated detection of blood vessels from digital retinal images

Due to the importance of the matched filter in the automated detection of blood vessels in digital retinal images, improving its response is highly desirable. This filter may vary in many ways depending on the parameters that govern its response. In this paper, new parameters to optimize the sensitivity of the matched filter are found using genetic algorithms on the test set of the DRIVE databases. The area under the receiver operating curve (ROC) is used as a fitness function for the genetic algorithm. To evaluate the improved matched filter, the maximum average accuracy (MAA) is calculated to be 0.9422 and the average area under ROC is 0.9582.

Opportunistic Uplilnk Scheduling for 3G LTE Systems

In this paper we propose a heuristic opportunistic scheduler that is consistent with the resource allocation constraints of the uplink channel for 3G long term evolution (LTE) systems. Retransmission processes as well as channel conditions are taken into account in the formation of the scheduling decision. The heuristic scheduler could be seen a reasonable choice for solving the constrained resource allocation maximization problem since it is computationally feasible and can find a practical solution. We also formulate an integer programming problem that provides a theoretical optimal solution. The heuristic scheduler was found to perform relatively well when compared to the optimal solution.

Fast Zernike moments

Zernike moments are important digital image descriptors used in various applications starting from image watermarking to image recognition. Lots of fast algorithms have been proposed to speedup the computation of Zernike moments. This work provides computational complexity analysis of methods for the computation of Zernike moments, as well as a thorough study and simplification to the methods of finding Zernike moments from geometric moments. A new formula that relates Zernike moments to moments of digital filters is introduced that is very efficient and accurate. Comparisons are performed using Zernike moment via geometric moments method, the Q-recursive method, the coefficient method, and the symmetry method. Using a well defined performance metric, this work finds out that Zernike moments from geometric moments of digital filters is nearly 70 times faster than the best method known as the symmetry method.

On the performance of Heuristic opportunistic scheduling in the uplink of 3G LTE networks

In this paper we study the performance of the heuristic localized gradient algorithm (HLGA) that was designed for uplink scheduling in 3G long term evolution (LTE) systems. The performance of the algorithm is examined when dynamic traffic models are assumed. With dynamic traffic, users will have different buffer occupancies. The amount of resources granted to a user need to be mapped to the size of those occupancies. We suggest for that, a procedure called dasiapruningpsila where resources are given to users who maximize a certain criteria and later on prune the extra resources and allocate them to other users. We also study the performance loss caused by more realistic assumptions on base station knowledge of the terminalpsilas buffer state. We first assume no delay in the reporting of the buffer occupancy but later evaluate the effect of buffer reporting delays and quantification of data used to report the status of a buffer.

Dynamic Protected-Subframe Density Configuration in LTE Heterogeneous Networks

The protected-subframe (PSF) structure is one of the methods for downlink inter-cell interference coordination (ICIC) utilized in heterogenous networks and is featured in Rel-10 of the technical specification for 3GPPs E-UTRAN. Static configuration of PSF has proven to increase performance but the dynamic configuration is yet to be examined. In this paper, we study the effect of dynamically configuring PSF density according to a certain criterion in an attempt to increase system performance and maintain a quality of service for all users. Results show that with full buffer traffic, the impact of dynamic configuration is more noticeable in cases of large pico cell range expansions. With dynamic traffic, we find that in the majority of cases, dynamic configuration outperforms the static. In this paper we consider two forms of PSF known as almost blank subframes (ABS) and reduced power subframes (RPS) and show the results from implementing both these techniques.

A dynamic approach for cell range expansion in interference coordinated LTE-advanced heterogeneous networks

Cell range expansion is one of the features of LTE-advanced where low power nodes in a heterogonous network can increase their coverage area and neighboring cells can offload particular users accordingly. The amount of expansion however can differ from one cell to another depending on the location of the low power node with respect to the neighboring cells, the cell load and the method of interference coordination utilized. A study is made in this paper to examine the impact of dynamically changing the range of low power nodes in the presence of a time based ICIC method. A simple heuristic method is proposed which adapts the size of the low power nodes to the load and interference situation. Results show that dynamic range expansion provides better performance for the 5th and 50th percentile users but causes loss to the 95th percentile users of a system.

Using Gabor filter for the illumination invariant recognition of color texture

We derive Gabor feature matrices that are used to recognize color texture independent of illumination changes. The feature depends on Gabor energy feature in which we derive a multi-band Gabor energy feature matrix. We also prove that two Gabor energy feature matrices such that represent two corresponding textures under different illumination are related by a linear transform. Experimental results show that the model is successful in recognizing color texture independent of the change in the spectral illuminations.

A dynamic TDD inter-cell interference coordination scheme for Long Term Evolution networks

In this paper we propose an inter-cell coordination scheme that coordinates the transmission time and mode of users in neighboring cells. The scheme is designed for 3G LTE systems and therefore takes into account interface constraints especially for the uplink. The objective of the scheme is to assign physical resource blocks together with the transmission mode to users in a way that minimizes interference by maximizing a utility function subject to a certain quality of service. Numerical results show that interference coordination with Dynamic-TDD actually provides significant gains when compared to Static-TDD for noticeable differences of traffic between the downlink and uplink.

Channel-aware inter-cell interference coordination for the uplink of 3G LTE networks

In this paper we propose a heuristic inter-cell coordination scheme for scheduling users in an opportunistic multi-cell network. The scheme is mainly designed to be implemented in the uplink of networks that utilize the Third Generation Partnership Project Long Term Evolution (3GPP LTE) technology. The objective of the scheme is to coordinate the uplink transmission in neighboring cells such that inter-cell interference is mitigated and the aggregate utility of the mobile users is maximized. In addition to the heuristic approach we formulate the inter-cell scheduling coordination as an integer programming problem. While the optimal solution cannot be realized in practice due to the computational complexity, it provides good insights of how well different algorithms perform. Numerical results show that the proposed coordination method delivers near-optimal performance in the exemplified cases.

Illumination invariant recognition of three-dimensional texture in color images

In this paper, illumination-affine invariant methods are presented based on affine moment normalization techniques, Zernike moments, and multiband correlation functions. The methods are suitable for the illumination invariant recognition of 3D color texture. Complex valued moments (i.e., Zernike moments) and affine moment normalization are used in the derivation of illumination affine invariants where the real valued affine moment invariants fail to provide affine invariants that are independent of illumination changes. Three different moment normalization methods have been used, two of which are based on affine moment normalization technique and the third is based on reducing the affine transformation to a Euclidian transform. It is shown that for a change of illumination and orientation, the affinely normalized Zernike moment matrices are related by a linear transform. Experimental results are obtained in two tests: the first is used with textures of outdoor scenes while the second is performed on the well-known CUReT texture database. Both tests show high recognition efficiency of the proposed recognition methods.