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The latest wireless communication systems focus on developing MIMO-OFDM systems that allow the transmission of very high data rates in fading environments. We can optimize these systems even further by setting the modulation and coding adaptively according to the channel conditions, and by using sub-carrier frequency and power allocation techniques. The overall system performance depends on the accuracy...
This paper is a review of studies dealing with Power Line Communication (PLC) in vehicle. The electronic control units (ECUs) that replace mechanical or hydraulic systems require specific buses in order to exchange information between sensors and actuators. Different networks as LIN, CAN, Flexray have been proposed, from low up to high data rate. Considering these networks, we can observe that each...
In-vehicle power line communication (PLC) provides a solution for high data communication in the automotive networks without increasing volume, weight and cost of the wiring harnesses. This paper presents the vehicle power line channel model. Also, we propose the design of baseband transceiver, which specifically aimed at this channel model. In transmitter part, the corresponding preamble structure...
The work presented herein proposes an algorithm for joint Carrier Frequency Offset (CFO) and channel estimation, acquisition and tracking, for OFDM systems in the presence of very high mobility. The algorithm is based on a parametric channel model. Assuming the path delays are known, the multi-path Rayleigh channel Complex Gains (CG) variation, within one OFDM symbol, is approximated by a Basis Expansion...
The 3GPP Long term Evolution (LTE) represents a major advance in cellular technology. This is designed to meet carrier needs for high-speed data and media transport as well as high-capacity voice support. The LTE PHY is a highly efficient means of conveying both data and control information between an enhanced base station and mobile user equipment. The LTE PHY employs some advanced technologies that...
Besides avoiding inter-symbol interference and leading to high capacity, wireless orthogonal frequency division multiplexing (OFDM) provide fine granularity for resource allocation since they are capable of dynamically assigning sub-carriers to multiple users and adaptively allocating transmit power. The current dominate layered networking architecture, in which each layer is designed and operated...
In the last years, the migration from analog to digital terrestrial television systems has favored the deployment of Single Frequency Networks (SFN), more efficient from a spectrum point of view, to provide DVB-T services in larger geographical areas through the reuse of frequencies. However, the planning of a SFN is not a trivial task, since the designer must find a trade-off between the quality...
Channel estimation is a significant component of any receiver implementation. This paper presents a fast non-iterative channel estimation and equalization algorithm for TDS-OFDM systems. The proposed method is a hybrid of CP-OFDM and ZP-OFDM systems. By discarding the initial portion of the PN-sequence that absorbs all the ISI, the channel can be estimated from the remaining PN-sequence by using the...
Realization of transmitter and Receiver architecture for LTE is the major research work being carried out by implementation experts. There are four Control channels available in LTE for both uplink and downlink. The uplink control channel is PUCCH. The downlink control channels are PDCCH, PCFICH and PHICH. The Physical Control Format Indicator Channel(PCFICH) is one among the downlink physical control...
This paper proposes time, frequency and clock synchronization technique for a Q transmit and L receive (Q x L), Multiple-Input Multiple-Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) for Wireless Local Area Network (WLAN) systems. OFDM is a multi-carrier modulation scheme that transmits a large number of closely spaced sub-carriers to be modulated with a conventional modulation technique...
In this paper, we propose a new robust closed-loop extended orthogonal space-time block coding (EO-STBC) scheme for two-way four relay networks over frequency selective fading channels with imperfect synchronization. It is a three time slot scheme where the first one is specified for the two terminals while the other two are specified for amplify-and-forward (AF) relays. An orthogonal frequency division...
Channel estimation in orthogonal frequency division multiplexing (OFDM) systems is required for coherent demodulation. This paper deals with channel estimation in the OFDM based LTE system. In particular, two pilot-aided techniques are presented: the low-pass filter based estimator (LPFE), and the robust minimum mean square error estimator (MMSE). These techniques are characterized by their low complexity...
WiMAX is a Worldwide Interoperability for Microwave Access. The technology is specified by the Institute of Electrical and Electronics Engineers Inc., as the IEEE 802.16 standard that works on development of globally standardized protocols for wireless MAN and it has been commercialized under the name “WiMAX”. 802-16-2004 has often been considered the “fixed standard” or “fixed WiMAX” and 802.16-2005...
Estimation of time-varying and sparse channels is a topic that has attracted considerable interest lately, especially for underwater acoustic communication. In the context of multicarrier transmission, several important questions remain unanswered: i) should pilots be placed in clusters as for time-varying, non-sparse channels, or randomly dispersed between the data as common in the Compressive Sensing...
In this paper, we study the impact of an important RF impairment inside direct-conversion receiver, namely the I/Q imbalance, on the performance of OFDM radio link over frequency-selective Rayleigh fading channel. Closed-form expressions for link performance, in terms of detection error rate, ergodic capacity and outage capacity, under both frequency-selective RX I/Q imbalance and noisy frequency-selective...
The use of distributed space-time codes in cooperative communications promises to increase the rate and reliability of data transmission. These gains were mostly demonstrated for ideal scenarios, where all nodes are perfectly synchronized. Considering a cooperative uplink scenario with asynchronous nodes, the system suffers from two effects: timing errors and individual carrier frequency offsets....
This paper discusses the performance of Golden codes in a hybrid satellite/terrestrial system framework employing dual polarized MIMO-OFDM transmissions. Although the use of Golden codes in satellite and terrestrial scenarios has been studied independently, a realistic performance assessment must involve both components taking into account the relative delay between their reception. In fact, this...
Due to wide coverage and high transmission power of digital television (DTV) transmitters, DTV based wireless positioning is a promising complementary to global positioning system. For Chinese DTV broadcasting network whose key technology is time-domain synchronous orthogonal frequency division multiplexing (TDS-OFDM), this paper proposes a time-frequency joint positioning scheme by utilising TDS-OFDM...
In this paper, we present a thorough investigation on the impact of spatial smoothing and forward-backward averaging techniques for subspace-based channel estimation. The spatial smoothing technique requires the selection of a window size, which, if not selected properly, leads to dramatically performance breakdown of the subspace-based methods. We aim to provide an explanation of the performance...
Long Term Evolution (LTE) is considered one of the main candidate to provide wireless broadband access to mobile users. Among main LTE characteristics, flexibility and efficiency can be guaranteed by resorting to suitable resource allocation schemes, in particular by adopting adaptive OFDM schemes. This paper proposes a novel solution to the sub-carrier allocation problem for the LTE downlink that...
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