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Mobile Ad-hoc Networks (MANET) and more specifically their vehicular variant (VANET) have to deal with fast changing channel conditions, specifically in urban areas. Routing protocols that have to build end to end paths over such volatile links typically react to link failure. In this paper we present a novel PHY layer based link state indicator which aims to predict such failure. The proposed link...
The Alamouti coded Space Frequency Block Code (SFBC) based Orthogonal Frequency Division Multiplexing (OFDM) scheme is upon analyzed by assuming that the Channel Frequency Response (CFR) remains constant over Alamouti code period (two adjacent OFDM subcarriers). But when the channel is highly frequency selective, this assumption does not hold good and causes inter-symbol-interferences (ISI). Thus,...
In CoMP, two or multiple transmitters are coordinated to establish links with users. For example, a pair of coordinated base stations can transmit Alamouti-coded data, which has two streams, with one base station being responsible for one stream. When multiple carrier frequency offsets exist, the performance of Alamouti-type schemes in CoMP degrades seriously. MCFOs can exist when transmitters are...
In this paper a modified iterative decoding algorithm (MIDA) is proposed for decoding the Cubic Product Codes (CPC), also called three dimensional product block codes. It is a hard decision decoder that was initially proposed by the same authors for decoding simple product codes, where the decoding complexity of the basic iterative algorithm was significantly reduced with negligible performance degradation...
The main objective of reliable radio packet data access is providing efficient data rates with minimum bandwidth requirement with low bit error rate(BER). To achieve all these requirements there is need to study characteristics of channel like ability to with stand for the errors. This paper analyses bit error rate(BER), by arbitrarily assuming AWGN channel with OFDM-MIMO (orthogonal frequency division...
In this paper, we evaluate and compare the performances of Viterbi decoding schemes based on soft decision and hard decisions, with results applicable to the Digital Video Broadcast-Terrrestial (DVB-T) standard. The standard suggests that the BER ≤ 2 × 10−4 at the decoder output is good enough for the quasi error-free condition. We assume that the channel state information (CSI) of all sub-carriers...
This paper proposes a work flow model of the LTE Downlink System in order to analyze the performance of the downlink communication and simulate this model to evaluate the key parameters like signal-to-noise ratio (SNR) and bit error rate (BER). It focuses on the implementation of the LTE downlink mainly in the physical layer. In the transmitter, functionalities like Turbo coding and OFDM has been...
Differential distributed space-time coding (D-DSTC) has been considered to improve both diversity and data-rate in cooperative communications in the absence of channel information. However, conventionally, it is assumed that relays are perfectly synchronized in the symbol level. In practice, this assumption is easily violated due to the distributed nature of the relay networks. This paper proposes...
In this paper, we study the design of frequency domain turbo equalization (FDTE) in single carrier (SC) multiple-input multiple-output (MIMO) systems, and prove the equivalence of two typical FDTE schemes under constant-modulus modulation. In the design of FDTE schemes, received signals and soft decision symbols obtained at the previous iteration are utilized to recover the transmitted symbols under...
In this paper, a differential space-time coding (D-STC) scheme is presented for relay assisted cooperative wireless communication networks over frequency selective fading channels. Two most common schemes, i.e., differential amplify-and-forward (DAF) and differential decode-and-forward (DDF), are both investigated in our single relay assisted system. Leveraging spectral encoder and differential space-time...
Orthogonal Frequency Division Multiplexing (OFDM) is a popular modulation technique that provides high data rates and good robustness against frequency selective fading. Space-Time Block Coding (STBC) is an efficient way to introduce space-time diversity in Multiple-Input Multiple-Output (MIMO) systems. Using non-linear modulations such as Continuous Phase Modulation (CPM) with its constant envelope...
Previously, a hybrid mechanism employing clipping and turbo coding was vindicated to be remarkably robust against impulse noise, characterized by strong power and frequent occurrence, in Orthogonal Frequency Division Multiplexing systems. This work aims at addressing the impulse noise together with the distortion induced by a more realistic transmitter configuration: Clipping and filtering for the...
In this paper, we present an energy efficient, and high speed analog fast Fourier transform (FFT) processor for Multi-Band Orthogonal Frequency Division Multiplexing (MB-OFDM) Ultrawideband (UWB) systems, although it is generally applicable to many other OFDM based receiver systems. The proposed high-speed, low power FFT architecture can provide higher throughput rate by using analog CMOS current...
Orthogonal Frequency Division Multiplexing (OFDM), aided by proper channel coding schemes, can realize very dependable transmission in fading channels. For the purpose of improving the performance of the OFDM based DRM digital AM broadcasting in MF and HF channels, this paper designs MLC-LDPC-OFDM transmission scheme that is suitable for MF and HF channels. The equivalent channel capacities of MLC-LDPC-OFDM...
The challenges and issues related to the application in IEEE 802.11ac systems of lattice reduction (LR) techniques for the implementation of successive interference cancellation (SIC) receivers in single-user (SU) and multi-user (MU) orthogonal frequency division multiplexing (OFDM) multiple input multiple output (MIMO) transceivers are investigated in this paper. The shown simulation results, validated...
In this contribution, we propose a novel Network Coding based LTE Cooperative-communication (NCLC) system. More specifically, our novel NCLC system is devised by incorporating a beneficial network coding scheme into the TD-LTE system. The benefit obtained by employing the network coding scheme in our NCLC systems are highlighted and analysed by both insightful formulae and illustrative examples. Particularly,...
Coding and decoding schemes are critical to the performance in wireless communication system. In Current coding scheme of LTE system, each transport block (TB) is segmented into several code blocks (CBs) which can be coded and decoded individually. If one of the CBs in a TB fails in decoding, the whole TB is required to be retransmitted. Channel estimation is very crucial for the correctness of the...
In a short-range multiple-input and multiple-output (SR-MIMO) transmission system that relies on line-of-sight (LOS) propagation, the channel matrix is determined by the antenna geometry, hence radio frequency (RF) signal processing by using an analog matrix circuit is a valid means of separating spatially-multiplexed multiple signal streams. To date several simple decoding methods utilizing this...
We consider a cooperative relay communication system where the source and the relay have separate frequency bands for message transmission. The relay is assumed to be a decode-forward node, i.e. It can decode the information send from the source node and re-transmit after suitable modifications. With power splitting at the source, we find an optimum relaying function which achieves the capacity of...
Algebraic Space-Time Codes (ASTC) for MIMO systems are based on quaternion algebras. Thanks to their algebraic construction, the ASTC codes, called the golden codes, are full-rank, full-rate and have the non-vanishing determinant property. Proposed for MIMO flat fading channels, these codes can increase the spectral efficiency and enhance the coding gain. ASTC codes maintain their proprieties for...
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