4,020 research outputs found
MIMO OFDM DOA Estimation Algorithm Implementation and Validation Using SDR Platform
The work is devoted to research in Mobile Station (MS) positioning techniques having opportunity and perspective of using in the next generation communication networks, particularly in cellular networks. Direction of Arrival (DOA) estimation is necessary in many positioning applications and has been well studied by academy and by industry. The main contribution of this work is to design and implement a computationally light direction of arrival estimator on a Multiple Input Multiple Output (MIMO) Software Defined Radio (SDR) platform. Implemented direction of arrival estimator is tested and validated in real conditions and experimental measurements show, that the implemented algorithm can accurately estimate the directions of arrived signals. Used algorithm, estimates direction of arrivals by processing received data of 16-element two dimensional planar antenna array. The algorithm uses initial data received from channel estimators and further process it to obtain direction information. The hardware implementation has been thoroughly analyzed and experimentally validated and open source host code is available on GitHub
MIMO OFDM DOA Estimation Algorithm Implementation and Validation Using SDR Platform
The work is devoted to research in Mobile Station (MS) positioning techniques having opportunity and perspective of using in the next generation communication networks, particularly in cellular networks. Direction of Arrival (DOA) estimation is necessary in many positioning applications and has been well studied by academy and by industry. The main contribution of this work is to design and implement a computationally light direction of arrival estimator on a Multiple Input Multiple Output (MIMO) Software Defined Radio (SDR) platform. Implemented direction of arrival estimator is tested and validated in real conditions and experimental measurements show, that the implemented algorithm can accurately estimate the directions of arrived signals. Used algorithm, estimates direction of arrivals by processing received data of 16-element two dimensional planar antenna array. The algorithm uses initial data received from channel estimators and further process it to obtain direction information. The hardware implementation has been thoroughly analyzed and experimentally validated and open source host code is available on Github
An FPGA implementation of OFDM transceiver for LTE applications
The paper presents a real-time transceiver using an
Orthogonal Frequency-Division Multiplexing (OFDM)
signaling scheme. The transceiver is implemented on a
Field-
Programmable Gate Array (FPGA) through Xilinx System
Generator for DSP and includes all the blocks needed
for the
transmission path of OFDM. The transmitter frame can be
reconfigured for different pilot and data schemes. In the
receiver, time-domain synchronization is achieved thr
ough a
joint maximum likelihood (ML) symbol arrival-time and
carrier frequency offset (CFO) estimator through the
redundant information contained in the cyclic prefix (CP).
A
least-squares channel estimation retrieves the channel
state
information and a simple zero-forcing scheme has been
implemented for channel equalization. Results show that a
rough implementation of the signal path can be impleme
nted
by using only Xilinx System Generator for DSP
Performance of an Echo Canceller and Channel Estimator for On-Channel Repeaters in DVB-T/H Networks
This paper investigates the design and performance of an FIR echo canceller for on-channel repeaters in DVB-T/H network within the framework of the PLUTO project. The possible
approaches for echo cancellation are briefly reviewed and the main guidelines for the design of such systems are presented. The main system parameters are discussed. The performance of an FIR echo canceller based on an open loop feedforward approach for channel estimation is tested for different radio channel conditions and for different number of taps of the FIR filter. It is shown that a minimum number of taps is recommended to achieve a certain mean rejection ratio or isolation depending on the type of channel. The expected degradation in performance due to the use of fixed point rather than floating point arithmetic in hardware implementation is presented for different number of bits. Channel estimation based on training sequences is investigated. The performance of Maximum Length Sequences and Constant Amplitude Zero Autocorrelation (CAZAC) Sequences is compared for different channels. Recommendations are given for training sequence type, length and
level for DVB-T/H on-channel repeater deployment
Direction of Arrival Estimation for Radio Positioning: a Hardware Implementation Perspective
Nowadays multiple antenna wireless systems have gained considerable attention due to their
capability to increase performance. Advances in theory have introduced several new schemes
that rely on multiple antennas and aim to increase data rate, diversity gain, or to provide
multiuser capabilities, beamforming and direction finding (DF) features. In this respect, it
has been shown that a multiple antenna receiver can be potentially used to perform radio
localization by using the direction of arrival (DoA) estimation technique.
In this field, the literature is extensive and gathers the results of almost four decades
of research activities. Among the most cited techniques that have been developed, we find
the so called high-resolution algorithms, such as multiple signal classification (MUSIC), or
estimation of signal parameters via rotational invariance (ESPRIT). Theoretical analysis
as well as simulation results have demonstrated their excellent performance to the point
that they are usually considered as reference for the comparison with other algorithms.
However, such a performance is not necessarily obtained in a real system due to the presence
of non idealities. These can be divided into two categories: the impairments due to the
antenna array, and the impairments due to the multiple radio frequency (RF) and acquisition
front-ends (FEs). The former are strongly influenced by the manufacturing accuracy and,
depending on the required DoA resolution, have to be taken into account. Several works
address these issues in the literature. The multiple FE non idealities, instead, are usually
not considered in the DoA estimation literature, even if they can have a detrimental effect
on the performance. This has motivated the research work in this thesis that addresses the
problem of DoA estimation from a practical implementation perspective, emphasizing the
impact of the hardware impairments on the final performance. This work is substantiated
by measurements done on a state-of-the-art hardware platform that have pointed out the
presence of non idealities such as DC offsets, phase noise (PN), carrier frequency offsets
(CFOs), and phase offsets (POs) among receivers. Particularly, the hardware platform will
be herein described and examined to understand what non idealities can affect the DoA
estimation performance. This analysis will bring to identify which features a DF system
should have to reach certain performance.
Another important issue is the number of antenna elements. In fact, it is usually limited by practical considerations, such as size, costs, and also complexity. However, the most
cited DoA estimation algorithms need a high number of antenna elements, and this does not
yield them suitable to be implemented in a real system. Motivated by this consideration,
the final part of this work will describe a novel DoA estimation algorithm that can be
used when multipath propagation occurs. This algorithm does not need a high number
of antenna elements to be implemented, and it shows good performance despite its low
implementation/computational complexity
Real-Time Localization Using Software Defined Radio
Service providers make use of cost-effective wireless solutions to identify, localize, and possibly track users using their carried MDs to support added services, such as geo-advertisement, security, and management. Indoor and outdoor hotspot areas play a significant role for such services. However, GPS does not work in many of these areas. To solve this problem, service providers leverage available indoor radio technologies, such as WiFi, GSM, and LTE, to identify and localize users. We focus our research on passive services provided by third parties, which are responsible for (i) data acquisition and (ii) processing, and network-based services, where (i) and (ii) are done inside the serving network. For better understanding of parameters that affect indoor localization, we investigate several factors that affect indoor signal propagation for both Bluetooth and WiFi technologies. For GSM-based passive services, we developed first a data acquisition module: a GSM receiver that can overhear GSM uplink messages transmitted by MDs while being invisible. A set of optimizations were made for the receiver components to support wideband capturing of the GSM spectrum while operating in real-time. Processing the wide-spectrum of the GSM is possible using a proposed distributed processing approach over an IP network. Then, to overcome the lack of information about tracked devices’ radio settings, we developed two novel localization algorithms that rely on proximity-based solutions to estimate in real environments devices’ locations. Given the challenging indoor environment on radio signals, such as NLOS reception and multipath propagation, we developed an original algorithm to detect and remove contaminated radio signals before being fed to the localization algorithm. To improve the localization algorithm, we extended our work with a hybrid based approach that uses both WiFi and GSM interfaces to localize users. For network-based services, we used a software implementation of a LTE base station to develop our algorithms, which characterize the indoor environment before applying the localization algorithm. Experiments were conducted without any special hardware, any prior knowledge of the indoor layout or any offline calibration of the system
Performance Comparison Between Music And Esprit Algorithms For Direction Estimation Of Arrival Signals
This thesis examines and compares the performance of Multiple Signal Classification (MUSIC) and Estimation of Signal Parameters via Rotational Invariance Techniques (ESPRIT) for the estimation of Direction of Arrival (DOA) of incoming signals to the smart antenna. The comparison of these two algorithms was done on the basis of parameters like number of array elements, number of incoming signals, angle difference between the incoming signals, number of the samples taken of signal, processing time and SNR ratio.
These two algorithms were implemented with MATLAB and SIMULINK for the experimental purpose. After all the experiments performed, it was analyzed that results obtained from both of the software were almost same.
Comparing MUSIC\u27s results with ESPRIT, it was found that MUSIC is less prone to error than ESPRIT for almost all parametric tests. This superiority of MUSIC made it desirable to recommend it for DOA estimation in smart antenna system
Wi-Fi Finger-Printing Based Indoor Localization Using Nano-Scale Unmanned Aerial Vehicles
Explosive growth in the number of mobile devices like smartphones, tablets, and smartwatches has escalated the demand for localization-based services, spurring development of numerous indoor localization techniques. Especially, widespread deployment of wireless LANs prompted ever increasing interests in WiFi-based indoor localization mechanisms. However, a critical shortcoming of such localization schemes is the intensive time and labor requirements for collecting and building the WiFi fingerprinting database, especially when the system needs to cover a large space. In this thesis, we propose to automate the WiFi fingerprint survey process using a group of nano-scale unmanned aerial vehicles (NAVs). The proposed system significantly reduces the efforts for collecting WiFi fingerprints. Furthermore, since these NAVs explore a 3D space, the WiFi fingerprints of a 3D space can be obtained increasing the localization accuracy. The proposed system is implemented on a commercially available miniature open-source quadcopter platform by integrating a contemporary WiFi - fingerprint - based localization system. Experimental results demonstrate that the localization error is about 2m, which exhibits only about 20cm of accuracy degradation compared with the manual WiFi fingerprint survey methods
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