Comparative Performance Evaluation of DVB-T using Advance Design System (ADS)

Wireless technologies have brought a rapid growth to digital video broadcasting and as such, has played (and still playing) a vital role in communication systems. Orthogonal frequency division multiplexing (OFDM) has also become so popular in wireless communication systems reason been that it has high spectral efficiency, high throughput, high data capacity and resilience to multipath fading. In addition to these, it is very robust to channel impairment; a quality which has made it preferable and ideal in wireless communication systems. This paper evaluates DVB and compares its performance across three different channels (AWGN, Rayleigh and Ricean) and three different modulation techniques (QPSK, 16 QAM and 64 QAM) is employed. DTV_DVB in 2K Mode carriers is transmitted across AWGN, Rayleigh and Ricean and a comparison of BER performance of the different modulation schemes was considered. At the end of the simulation results and analysis, it was found that AWGN in 16QAM carrier modulation is considered the best modulation technique for DVB_T. Keywords: modulation, channel, digital television, digital video broadcasting

Hardware simulator design for LTE applications with time-varying MIMO channels

International audienceA hardware simulator facilitates the test and validation cycles by replicating channel artifacts in a controllable and repeatable laboratory environment. This paper presents new frequency domain and time domain architectures of the digital block of a hardware simulator of MIMO propagation channels. The two architectures are tested with LTE standard, in outdoor environment, using time-varying channels. The new architectures of the digital block are presented and designed on a Xilinx Virtex-IV FPGA. Their accuracy and latency are analyzed. The result shows that the architectures produce low occupation on the FPGA and have a small relative error of the output signals

Including general environmental effects in K-factor approximation for rice-distributed VANET channels

© 2014. This paper presents a method of approximating the Rician K-factor based on the instantaneous static environment. The strongest signal propagation paths are resolved in order to determine specular and diffuse powers for approximation. The model is experimentally validated in two different urban areas in New South Wales, Australia. Good agreement between the model and experimental data was obtained over short-range communication links, demonstrating the suitability of the model in urban VANETs. The paper concludes with recommendations for methods to account for vehicles in the simulation and incorporating additional phenomena (such as scattering) in the approximation

Design and theoretical analysis of advanced power based positioning in RF system

Accurate locating and tracking of people and resources has become a fundamental requirement for many applications. The global navigation satellite systems (GNSS) is widely used. But its accuracy suffers from signal obstruction by buildings, multipath fading, and disruption due to jamming and spoof. Hence, it is required to supplement GPS with inertial sensors and indoor localization schemes that make use of WiFi APs or beacon nodes. In the GPS-challenging or fault scenario, radio-frequency (RF) infrastructure based localization schemes can be a fallback solution for robust navigation. For the indoor/outdoor transition scenario, we propose hypothesis test based fusion method to integrate multi-modal localization sensors. In the first paper, a ubiquitous tracking using motion and location sensor (UTMLS) is proposed. As a fallback approach, power-based schemes are cost-effective when compared with the existing ToA or AoA schemes. However, traditional power-based positioning methods suffer from low accuracy and are vulnerable to environmental fading. Also, the expected accuracy of power-based localization is not well understood but is needed to derive the hypothesis test for the fusion scheme. Hence, in paper 2-5, we focus on developing more accurate power-based localization schemes. The second paper improves the power-based range estimation accuracy by estimating the LoS component. The ranging error model in fading channel is derived. The third paper introduces the LoS-based positioning method with corresponding theoretical limits and error models. In the fourth and fifth paper, a novel antenna radiation-pattern-aware power-based positioning (ARPAP) system and power contour circle fitting (PCCF) algorithm are proposed to address antenna directivity effect on power-based localization. Overall, a complete LoS signal power based positioning system has been developed that can be included in the fusion scheme --Abstract, page iv

Hardware Simulator Design for MIMO Propagation Channel on Shipboard at 2.2 GHz

27 pagesInternational audienceA wireless communication system can be tested either in actual conditions or with a hardware simulator reproducing actual conditions. With a hardware simulator it is possible to freely simulate a desired radio channel, making it possible to test "on table" mobile radio equipments. This paper presents new architectures for the digital block of a hardware simulator ofMIMO propagation channels. This simulator can be used for LTE and WLAN IEEE 802.11ac applications, in indoor and outdoor environments. However, in this paper, specific architectures of the digital block of the simulator for shipboard environment are presented. A hardware simulator must reproduce the behavior of the radio propagation channel. Thus, ameasurements campaign has been conducted to obtain the impulse responses of the shipboard channel using a channel sounder designed and realized at IETR. After the presentation of the channel sounder, the channel impulse responses are described and implemented. Then, the new architectures of the digital block of the hardware simulator, implemented on a Xilinx Virtex-IV FPGA are presented. The accuracy, the occupation on the FPGA and the latency of the architectures are analyzed

MIMO Hardware Simulator Design for Outdoor Time-Varying Heterogeneous Channels

1-4International audienceThis paper presents a hardware simulator of Multiple- Input Multiple-Output (MIMO) propagation channels. The hardware simulator reproduces a desired radio channel and makes it possible to test "on table" different MIMO systems. A specific architecture of the digital block of the simulator is presented to characterize an outdoor scenario for Long Term Evolution (LTE) systems. An algorithm is introduced to switch between the impulse responses and to control the time variation of the delays. The new architecture is designed on a Xilinx Virtex-IV Field Programmable Gate Array (FPGA). Its accuracy, occupation on the FPGA and latency are analyzed

Channel-predictive link layer ARQ protocols in wireless networks

Communication performance over a wireless channel should be considered according to two main parameters: energy and throughput. The reliable data transfer is a key to these goals. The reliable node-to-node data transfer is performed by link layer protocols. One prominent approach is Automatic Repeat Request (ARQ) protocol. The traditional ARQ protocols attempt to recover the erroneously transmitted frames by retransmitting those frames, regardless of the channel state. Since this channel state unaware behaviour may cause unnecessary retransmissions, traditional ARQ protocols are expected to be energy inefficient. Some ideas have been proposed such as stochastic learning automaton based ARQ, and channel probing based ARQ. However, these algorithms do not attempt to estimate the channel\u27s existing condition. Instead, the retransmission decision is made according to a simple feedback, on whether the previous frame was successful. This thesis presents four proposed algorithms, which incorporates the channel state estimate in the feedback process to judiciously select a frame (re)transmission timing instant. Algorithms have been applied on Stop-and-Wait (S-W) ARQ, and the performance have been compared with respect to simple S-W ARQ, and probing based S-W ARQ. In probing based ARQ, when the channel deteriorates, transmitter starts probing channel periodically, but the periodicity is chosen arbitrarily, regardless of the fading state. In contrast, the proposed algorithms estimate the channel\u27s existing condition by using feedbacks, and the probing interval is chosen according to the Average Fading Duration (AFD) of received signal. Simulations are performed with Rayleigh Fading Channel. The performance results show that at the cost of some additional delay, significiant gain on energy saving and throughput performance can be achieved when AFD based intelligent probing is done