Erhan A. Ince

Efficient expression and bound for pairwise error probability in Rayleigh fading channels, with application to union bounds for turbo codes

This work provides a new exact expression for the pairwise error probability under perfect channel state information. Using this expression, the average union upper bounds for (1,7/5,7/5) and (1,5/7,5/7) turbo coding schemes are presented based on transfer function approach assuming fully interleaved Rayleigh fading channels. Derivation for the pairwise error probability leads to a compact approximation which overlaps with the exact expression. This new approximation is computationally more efficient than the existing ones, and leads to a much quicker general ion of union bounds for performance analysis.

Closed form expression and improved bound on pairwise error probability for performance analysis of turbo codes over Rician fading channels

This letter provides derivations for an exact expression and a bound on pair wise error probability over fully interleaved Rician fading channels under the assumption of ideal channel state information. The derivation which is based on the probability distribution of the sum of squared Rician random variables leads to an improved upper bound in comparison with the only known bound in literature. Pairwise error probability plots together with average union upper bounds for turbo codes having (1,7/5,7/5) and (1,5/7,5/7) generator polynomials are presented to demonstrate the effectiveness of the new results

Priority-aware downlink frame packing algorithm for OFDMA-based mobile wireless systems

In this paper, downlink frame packing in OFDMA-based mobile wireless communication systems is addressed by extending an existing low-complexity frame packing algorithm. In particular, a realistic channel model and users with variable bit rates are used for evaluating the performance of the packing algorithms. The first extension involves allowing the unallocated bursts to be transmitted in upcoming frames. The average percentage of the unallocated bursts is improved to 0.0014% compared to 0.584% obtained with the standard eOCSA algorithm. The second extension involves assigning priorities to bursts in order to support possible quality of service requirements by users. With two different service classes, the average percentage of the unallocated bursts for the priority-aware case is 0.0048%.

Exact expression and tight bound on pairwise error probability for performance analysis of turbo codes over nakagami-m fading channels

This letter presents derivation for an exact and efficient expression on pairwise error probability over fully interleaved Nakagami-m fading channels under ideal channel state information at the decoder. As an outcome, this derivation also leads to a tight upper bound on pairwise error probability which is close to the exact expression. Pairwise error probability plots for different values of Nakagami parameter m along with an already existing numerically computable expression are provided. As an application of pairwise error probability, average union upper bounds for turbo codes having (1,7/5,7/5) and (1,5/7,5/7) generator polynomials employing transfer function approach are presented to illustrate the usefulness of the new efficient results

Interference management in two-tier heterogeneous networks using blind interference alignment

The paper presents a new solution for interference management in downlink (DL) heterogenous networks where macrocell base station (MBS) and neighboring femtocell base stations cause interference on femtocell users. A novel scheme is proposed where the i-th macrocell user (MU-i, i = 1, ..., F) and the i-th femtocell (FC-i, i = 1, ..., F) form a pair ([MU-i FC-i] pair), and pairs are orthogonal ([MU-i FC-i] orthogonal to [MU-j FC-j], where i is not equal to j). Without loss of generality, it is assumed that ith macrocell user and femtocell are chosen. In each femtocell, blind interference alignment (BIA) using staggered antenna switching is utilized and the paired macrocell users streams are aligned on the predetermined interference dimensions of the femtocell users set by BIA. For the baseline, it is assumed all femtocells, where BIA is applied in each, share their reserved resources thus causing significant interference on each other, and the macrocell users are orthogonal to all femtocells. It is shown that the degrees of freedom of the proposed and the baseline schemes in the case of 2 femtocells each with 2-user 2 × 1 multiple-input single-output (MISO) broadcast channels (BCs) is 7/3 and 1, respectively. Numerical results also show that the sum-rate of the proposed scheme is higher compared with the baseline where MBS applies zero-forcing precoder with water filling power allocation. The novel proposed scheme can be extended to a general network via judicious selection and orthogonalization approaches.

Entropy-based subspace separation for multiple frequency estimation

A subspace-based algorithm for estimating the order and the frequencies of multiple sinusoids embedded in noise is proposed. The new estimator (referred to as E-MUSIC) uses the entropy of a random variable related to the angles between the signal and noise subspaces as its objective function. Maximizing the entropy tends to achieve uniform angle distribution and thus leads to maximal subspace separation. The entropy-based objective function and the performance of the E-MUSIC algorithm is compared with some reference algorithms in the literature. Simulations which are performed in additive white and colored Gaussian noise show that the E-MUSIC offers an improvement for both model order and multiple frequency estimation. The improvement is more pronounced for high model orders and large SNR values.

Traffic analysis of avenues and intersections based on video surveillance from fixed video cameras

Based on adaptive Gaussian mixture modelling this article presents the separation of foreground objects from frames of surveillance video taken at avenues and/or intersections. The paper also describes an approach for determining the lane fullness of a dedicated leg of an intersection. In order to give an accurate fullness measure the cast shadows that might be present in the segmented foregrounds must be eliminated. In this study the detection and removal of shadows have been carried out using the HSV color space. The simulations were carried out using the Camera 1 sequence from PETS 2001 database and a custom sequence recorded in TRNC-Famagusta. A new method for computing right and left lane fullness in each leg of the intersection has been proposed and values computed have been recorded on the bottom left corner of the frame under study.

Rule Based Segmentation and Subject Identification Using Fiducial Features and Subspace Projection Methods

This paper describes a framework for carrying out face recognition on a subset of standard color FERET database using two different subspace projection methods, namely PCA and Fisherfaces. At first, a rule based skin region segmentation algorithm is discussed and then details about eye localization and geometric normalization are given. The work achieves scale and rotation invariance by fixing the inter ocular distance to a selected value and by setting the direction of the eye-to-eye axis. Furthermore, the work also tries to avoid the small sample space (S3) problem by increasing the number of shots per subject through the use of one duplicate set per subject. Finally, performance analysis for the normalized global faces, the individual extracted features and for a multiple component combination are provided using a nearest neighbour classifier with Euclidean and/or Cosine distance metrics.

A simple moment based approximation to pairwise error probability for memoryless fading channels

This paper provides a simple approximation to pairwise error probability for memoryless fading channels when there is no channel state information at the decoder. The derived approximation is independent of the fading process and depends only on the mean and variance of the fading distribution. The new approximation is considerably better than an already existing approximation and a bound for low signal to noise ratio values. It can be applied to obtain average union upper bounds for block and turbo-like coding schemes. Plots for pairwise error probability for Rician, Rayleigh and Nakagami-m fading channels along with average union upper bounds for turbo codes with (1,5/7,5/7) generator polynomial are given to illustrate improvement in already published work

Subspace Alignment and Separation for Multiple Frequency Estimation

In this letter, a new subspace based estimator that can effectively provide the order and frequencies of multiple sinusoids in noise is proposed. The estimator, referred to as SAS-Est (Subspace Aligning and Separating Estimator), simultaneously seeks to separate the steering vectors from the noise subspace and align them to the signal subspace. The angles between subspaces and the generalized Kullback-Leibler divergence are used in characterizing the alignment and separation. Minimizing the divergence leads to maximal subspace separation and best alignment, thus allowing improved performance. Simulations in additive white Gaussian noise show that the new estimator offers an improvement for both model order and frequency estimation. When compared with other methods, the improvement is more pronounced for high model orders and low signal-to-noise ratio values.