Farhad Mehran

Wireless MIMO systems employing joint turbo-like STBC codes with bit-level algebraically-interleaved URSCs

In this paper, permutations constructed based on algebraic derivations which are of particular interests due to better error-rate performance as well as simpler and practical hardware implementations, have been used in designing high performance fully-systematic joint space-time turbo coding technology. This scheme enjoys the integration of twin-/triplet-antenna bit-level space-time (ST) codes with the binary turbo-like codes of unpunctured codecs. The conducted performance evaluations reveal that this scheme has superior flare performance and yields additional coding gains in waterfall region, compared with the row-column block interleaved systems.

Performance evaluation of Serial Concatenated Convolutional Codes over aeronautical channels

In order to support an acceptable quality-of-service (QoS) in mobile wireless communication systems in terms of physical layer metrics, Serial Concatenated Convolutional Codes (SCCCs) are emerging as a strong candidate, promising remarkable coding gains with reasonable decoding complexities. This work addresses the performance evaluation of SCCCs over aeronautical channels, based on a ground-to-air scenario, where the fixed transmitter is on the ground operating in the 24–26 MHz band, and the mobile receiver is considered to be a commercial Boeing 747 airplane. The thorough investigation on the performance of system in a case of various channel conditions during the take-off and cruising stages of the flight are considered, and the SCCCs performance parameters are adopted to fulfill the bit-error-rate (BER) requirements. The simulations are based on the worst-case scenario for ground-to-air mobile wireless communications, where the line-of-sight (LOS) is blocked by high buildings or mountains.

Short-length FSU-SCQICs over coherent and incoherent stochastic aeronautical MISO channels

Multi-antenna systems play a major role in modern wireless systems due to their outstanding capability in alleviating deconstructive addition of multipath echoes and interferences from other users in wireless media. However, the performance of numerous technologies such as high-performance forward error correction (FEC) codes still have not been sufficiently examined under various multi-antenna wireless propagation environments. This short paper presents the performance of the integrated fully systematic unpunctured (FSU) serial concatenation of quadratic interleaved codes (SCQICs) and Alamouti dual-antenna space-time codes over coherent and incoherent stochastic aeronautical multiple-input single-output (MISO) wireless propagation links.

Serial concatenation of quadratic interleaved codes in different wireless doppler environments

The remarkable development of mobile networks has enabled ubiquitous communications that has transformed the way people connect with each other. Meanwhile, the growing adoption of smartphones, tablets, and increasingly bandwidth-intensive applications and services is driving unprecedented mobile broadband traffic growth; therefore, finding state-of-the-art strategies for improving the wireless transmission reliability has emerged significantly. In particular, to enable significant mitigation of the detrimental effects of multipath fading, high-performance forward error correction (FEC) techniques have now recognized to become a vital part of modern digital wireless systems. This work is dedicated to address a class of high-performance iteratively decoded FECs referred to as serial concatenation of quadratic interleaved codes (SCQICs) wherein the reordering arrays for permutor and unscramble in the FEC encoding/decoding entities enjoy the remarkable algorithm proposed by Takeshita et al. seminal contribution which: (1) yields provisioning coding gain in both waterfall and error-floor regions of the bit error rate (BER) performance curve (2) enables possibility of analysis and compact representation, (3) requires straightforward implementation. We have observed that their utilization for the modern wireless communications applications remained scarce due to the lack of strong and comprehensive performance predictions over the different statistical wireless channel models. Hence, in this paper, we endeavor to analyze and examine the error-correction capability of SCQICs vastly from the various aspects, and investigate their resultant coding gains in different wireless Doppler environments.

Joint space-time algebraically-interleaved turbo-like Coded Incoherent MIMO systems with optimal and suboptimal MAP probability decoders

The outstanding coding gains and also the practical complexities of the turbo-coded communication systems, heavily depend on the iterative soft-decision decoding algorithm used for the soft-input/-output component decoders. The goal of this paper is to address the investigation on the energy gaps of the enhanced channel coding entity of [1], when original and also approximated logarithmic-based iterative MAP algorithms are employed for the iterative near maximum-likelihood (ML) decoding. As far as the large decoding delays of the turbo and turbo-like code structures constitute a major disadvantage for these types of channel-codes, the previously introduced high-performance channel-codes of [1] are developed for the original and also approximated iterative BCJR-MAP turbo decoders to enable the higher level of selection flexibility in error-rate versus computational complexity tradeoff. We examine the required energy per bit Eb and the noise power spectral density N0 ratio to attain the BER ≈ 10-4 - 10-5 for the differentially encoded phase-shift keying (D-PSK) MIMO Rayleigh fading channels.

Decoupling numerical performance evaluation of microwave antennas feeding network

This paper presents decoupling analysis and numerical performance evaluation of a microwave antenna feeding network for enhancing the isolation between coupled microwave antennas. The RF network linearly combines the input signals in order to force the antennas microwave mutual coupling between the ports become zero. The objective of this RF investigation is to develop a mathematically designed feeding network intended for a suitable use in a 2×2 monopole RF antenna array. The microwave feeding network demonstrates the appropriateness in order to develop a well-established analysis model for microwave feeding networks.