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In this paper, we propose a joint content and channel aware (JCCA) resource allocation algorithm for video transmission in OFDMA relay system. It can maximize accumulation of allocated subcarriers' contribution for video transmission so as to improve overall quality of users' received video under resource constrained conditions. As is explained in this work, the algorithm is implemented by packet...
In this paper, the performance of the Least Squares (LS) estimator along with turbo codes in OFDM is evaluated for the SUI channel models in the presence of AWGN. Turbo codes are used in this paper because of its BER performance close to Shannon limit. The iterative turbo decoder exchanges soft information between the component decoders. Maximum A Posteriori (MAP) and its simplified version Max-Log-MAP...
In this paper, we propose IB-DFE receiver (Iterative Block Decision Feedback Equalization) with iterative SISO LDPC decoding (soft-input soft-output - Low Density Parity Code) suitable for SC-FDE (Single- Carrier with Frequency-Domain Equalization) with multilevel modulations. This scheme can be implemented in a simple way using an analytical characterization where the any multilevel constellation...
This paper proposes a two dimensional (2D) code, which has vertical raptor-like rate-compatible LDPC code and horizontal Reed Solomon (RS) code, for the terrestrial CTxn system. The proposed 2D code not only removes error-floor phenomenon with a help of RS code, but also does not require a complex interleaver for stable reception under fading channels because the 2D code itself provides block-type...
We consider a multiuser scenario with a center node for data fusion, where simultaneously transmitting is required in real time and with low probability of interception. We established a novel multiple access scheme, named matrix division multiple access (MDMA), based on OFDM technology. Precoded with different matrices, the signal from different end nodes can be distinguished due to the signal space...
Recent advances in microwave technology and signal processing have unveiled the potential of the so-called wireless power transfer (WPT) from one device to the other. This has resulted in reducing the need of a local power source at the wireless devices. In this paper, we target a popular physical layer technology, namely the orthogonal frequency division multiplexing (OFDM) and propose a novel approach...
Vehicular wireless channels are highly time-varying and the pilot pattern in the 802.11p orthogonal frequency-division multiplexing frame has been shown to be ill suited for long data packets. The high frame error rate in off-the-shelf chipsets with noniterative receiver configurations is mostly due to the use of outdated channel estimates for equalization. This paper deals with improving the channel...
This paper considers the coded OFDM system and instead of discarding the cyclic prefix (CP) at the receiver, we utilize the CP observation for joint detection, decoding and channel estimation. In particular, detection and decoding are performed iteratively between an equalizer and a soft-input soft-output (SISO) decoder based on the turbo principle, and the expectation-maximization (EM) algorithm...
Fountain Codes belongs to the class of rateless codes[4] which effectively improves the performance of systems used for wireless data transmission. In this paper, we present a quantitative analysis of Fountain Coded Orthogonal Frequency Division Multiplexing (OFDM) systems over Rician faded channel. Bit Error Rate (BER) performance evaluation and comparison is carried out for Fountain Coded and Convolution...
In what follows signal-code constructions employing block and convolutional nonbinary inner codes that can perform under severe jamming are proposed. Robustness of the proposed signal-code constructions to jamming is verified by means of simulation.
In this paper we investigate multiple access schemes and multi-carrier waveforms in the context of future 5th Generation (5G) wireless communication systems. We compare classical Frequency Division Multiple Access (FDMA) to Interleave-Division Multiple Access (IDMA) on top of two different multicarrier waveforms: Orthogonal Frequency Division Multiplexing (OFDM) and a new approach called Universal...
In cellular systems, the interference has been the most critical issue that practically limits the performance of overall networks. Furthermore, the distribution of the inter-cell interference (ICI) in conventional cellular networks employing orthogonal frequency-division multiple-access (OFDMA) with quadrature amplitude modulation (QAM) tends to approach a Gaussian distribution, which is known to...
Physical layer cooperation of a source with a relay can significantly boost the performance of a wireless connection. However, the best practical relaying scheme can vary depending on the relative strengths of the channels that connect the source, relay and destination. This paper proposes and evaluates QUILT, a system for physical-layer relaying that seamlessly adapts to the underlying network configuration...
Reactive jamming is considered the most powerful jamming attack as the attack efficiency is maximized while the risk of being detected is minimized. Currently, there are no effective anti-jamming solutions to secure OFDM wireless communications under reactive jamming attack. On the other hand, MIMO has emerged as a technology of great research interest in recent years mostly due to its capacity gain...
This paper is concerned with the performance analysis of a Single Code Superposition Coded Modulation Orthogonal Frequency Division Multiplexing (SC-SCM-OFDM) communication system. A simple Chip-By-Chip (CBC) iterative Multi User Detection (MUD) strategy is used in SC-SCM-OFDM system. The performance of SC-SCM-OFDM has been studied over Additive White Gaussian Noise (AWGN), Jack fading and Rician...
Quadrature Orthogonal Frequency Division multiple access (Q-OFDMA) has been renowned as a promising technique which provides a solution to the high PAPR (Peak to average power ratio), sensitivity to carrier frequency offset (CFO) problem and design complexity as introduced by the normal OFDMA systems. Exploiting this Q-OFDMA systems on the Multi-Input Multi-Output (MEMO) architecture, leads to a remarkable...
MU-MIMO-OFDM is an effective technique to achieve high capacity and reliable wireless communications systems because both the robustness against multipath fading and the high spectrum efficiency can be effectively achieved by the combination of OFDM with MU-MIMO. However, MU-MIMO-OFDM significantly suffers from the nonlinear distortion which is a main drawback of OFDM. In this paper, we propose nonlinear...
Pilot subcarriers are very useful in the measurement of channel indicator such as CINR, frequency offset estimation and channel estimation. They are applied widely in many existing standards such as IEEE 802.11, IEEE 802.16 and IEEE 802.22. In this paper, a set of pilot patten is proposed for a network operating in VHF/UHF band based on 802.16 WiMax design pattern. Rationales behind the choice of...
Periodic impulsive noise synchronous to the main powerline frequency is the dominant noise component in OFDM-based narrowband (NB) powerline communications (PLC). Such noise occurs in periodic bursts, where a single burst could corrupt multiple OFDM symbols. Standardized NB PLC systems use frequency-domain interleaving (FDI) in combination with forward error correction to combat impulsive noise. Alternate...
Pre-processing (PP) of received symbol vector and channel matrices is an essential pre-requisite operation for Sphere Decoder (SD)-based detection of Multiple-Input Multiple-Output (MIMO) wireless systems. PP is a highly complex operation, but relative to the total SD workload it represents a relatively small fraction of the overall computational cost of detecting an OFDM MIMO frame in standards such...
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