ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, Nevada / Transmitter mobility and multipath propagation make the telemetry channel both time and frequency selective, which results in telemetry link errors, sometimes in crucial flight phases. Only part of these impairments are compensated by various diversity techniques, but a fast converging adaptive channel equalization is probably the best suited and most cost effective solution. This paper first presents an analysis of mobile multipath propagation in telemetry based on recorded operational signals, both at the transmitter and at the receiver sides. Then it provides performance evaluation of a novel blind equalizer, assessed by offline processing of the recorded signals. The paper focuses on typical environments at a flight test centre, which exhibit critical multipath channel characteristics, namely during parking, taxiway and flight. The channel analysis exploits the recorded signals as well as the time frequency response of the novel equalizer filter. Performance evaluation shows that the equalizer outperforms state of the art Constant Modulus Algorithm (CMA). In particular, it is shown to significantly increase the telemetry link availability even in severe conditions, sometimes from nearly 0% to almost 100%, whereas the CMA fails to improve the signal quality as soon as the channel varies in time.

Submitted by PPG Engenharia El?trica (engenharia.pg.eletrica@pucrs.br) on 2018-04-23T19:26:15Z No. of bitstreams: 1 KAYOL_SOARES_MAYER_DIS.pdf: 19305237 bytes, checksum: 0750bd8f9d1820565918888661bc5acb (MD5) / Approved for entry into archive by Sheila Dias (sheila.dias@pucrs.br) on 2018-05-04T12:47:14Z (GMT) No. of bitstreams: 1 KAYOL_SOARES_MAYER_DIS.pdf: 19305237 bytes, checksum: 0750bd8f9d1820565918888661bc5acb (MD5) / Made available in DSpace on 2018-05-04T13:13:01Z (GMT). No. of bitstreams: 1 KAYOL_SOARES_MAYER_DIS.pdf: 19305237 bytes, checksum: 0750bd8f9d1820565918888661bc5acb (MD5) Previous issue date: 2018-03-28 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Em sistemas de comunica??o digital sem fio, o sinal transmitido pode ser afetado por v?rias fontes de distor??o, sendo as mais significantes o ru?do gaussiano branco aditivo (AWGN), multipercurso e efeito Doppler. Em ambientes onde a resposta de impulso do canal de comunica??o ? vari?vel no tempo, como em comunica??es m?veis, a distor??o por multipercurso ? din?mica. Juntamente com o efeito Doppler, o multipercurso din?mico pode at? mesmo eventualmente interromper completamente o link de comunica??o sem fio. Para minimizar este problema, equalizadores de canais autodidatas s?o usados para mitigar os efeitos de multipercurso e Doppler. Neste contexto, esta disserta??o prop?e um novo equalizador de canal autodidata (blind), baseado no algoritmo de m?dulo constante modificado n?o linear (NMCMA) e no equalizador Soft Direct Decision (SDD) em uma arquitetura concorrente. Este novo equalizador concorrente NMCMA-SDD ? comparado com o estado da arte, o equalizador concorrente com algoritmo de m?dulo constante (CMA)-SDD, operando sob os chamados "Brazil channels A-E", proposto pela Uni?o Internacional das Telecomunica??es (UIT). O equalizador proposto apresenta resultados significativos em compara??o com o estado da arte, possibilitando a opera??o em links de comunica??o sem fio entre ve?culos a?reos n?o tripulados (UAVs), ve?culos terrestres e em outros cen?rios de comunica??o din?mica. / In wireless digital communication systems, the transmitted signal may be affected by several sources of distortion, the most significant being Additive Whit Gaussian Noise (AWGN), multipath and Dopplr effect. In environmets where the impulse response of the communication channel is time variant, as in mobile communications, the multipath distortion is dynamic. Together with the Doppler effect, the dynamic multipath may even completely interrupt the wireless communication link. In order to solve this issue, blind channel equalizers are used to mitigate the multipath and Doppler effects. In this context, this dissertation proposes a novel blind channel equalizer, based on the Nonlinear Modified Constant Modulus Algorithm (NMCMA) and on the Soft Direct Desicion (SDD) equalizers in a concurrent architecture. This novel NMCMA-SDD concurrent equalizer is compared with the state of the art, the Constant Modulus Algorithm (CMA)-SDD concurrent equalizer, over the so-called "Brazil channels A-E", proposed by the International Telecommunication Union (ITU). The proposed equalizer presents significant results when compared with the state of the art, making possible its operation in wireless communication links for Unmanned Aerial Vehicles (UAVs), terrestrial vehicles, and others dynamic communication scenarios.

Doctor of Philosophy(PhD) / In this thesis, we propose and investigate promising approaches for interference mitigation in multiple input multiple output (MIMO) and code division multiple access (CDMA) systems. Future wireless communication systems will have to achieve high spectral efficiencies in order to meet increasing demands for huge data rates in emerging Internet and multimedia services. Multiuser detection and space diversity techniques are the main principles, which enable efficient use of the available spectrum. The main limitation for the applicability of the techniques in these practical systems is the high complexity of the optimal receiver structures. The research emphasis in this thesis is on the design of a low complexity interference suppression/cancellation algorithm. The most important result of our research is the novel design of interference cancellation receivers which are adaptive and iterative and which are of low computational complexity. We propose various adaptive iterative receivers, based on a joint adaptive iterative detection and decoding algorithm. The proposed receiver can effectively suppress and cancel co-channel interference from the adjacent antennas in the MIMO system with a low computation complexity. The proposed adaptive detector, based on the adaptive least mean square (LMS) algorithm, is investigated and compared with the non-adaptive iterative receiver. Since the LMS algorithm has a slow convergence speed, a partially filtered gradient LMS (PFGLMS) algorithm, which has a faster convergence speed, is proposed to improve the convergence speed of the system. The performance and computational complexity of this receiver are also considered. To further reduce the computational complexity, we apply a frequency domain adaptation technique into the adaptive iterative receivers. The system performance and complexity are investigated. It shows that the computational complexity of the frequency domain based receiver is significantly lower than that of the time domain based receiver with the same system performance. We also consider applications of MIMO techniques in CDMA systems, called MIMO-CDMA. In the MIMO-CDMA, the presence of the co-channel interference (CCI) from the adjacent antennas and multiple access interference (MAI) from other users significantly degrades the system performance. We propose an adaptive iterative receiver, which provides the capability to effectively suppress the interference and cancel the CCI from the adjacent antennas and the MAI from other users so as to improve the system performance. The proposed receiver structure is also based on a joint adaptive detection and decoding scheme. The adaptive detection scheme employs an adaptive normalized LMS algorithm operating in the time and frequency domain. We have investigated and compared their system performance and complexity. Moreover, the system performance is evaluated by using a semi-analytical approach and compared with the simulation results. The results show that there is an excellent agreement between the two approaches.

Nowadays the technologies of communication are widely developing due to the huge requirements in the world, such as asymmetric digital subscriber line (ADSL), wireless fidelity (Wi-Fi), and high definition television (HDTV). We are seeking for high performance and quality communication schemes. The scheme of orthogonal frequency division multiplexing (OFDM) catches everyone's eyes due to the advantages of the OFDM. Not only high bit rate in the long haul transmission but also reconfigurable network is the charming contention, and the penalties are reduced by the cyclic prefix which can reduce the inter-symbol interference (ISI). In this thesis, I will introduce the demand for optical fiber communications, then, interpret the motivation and the organizations in a nutshell. Next, the theoretical studies will be discussed, including mathematical formulations and basic theories of one tap equalizer, a cyclic prefix, a training symbol synchronization, and a discrete multitone (DMT) modulation. In addition, the experimental setups are successfully constructed and used for verifying the impact of one tap equalizer and the training symbol synchronization. Also, the performance of the systems are measured. Finally, the thesis is concluded.

This paper designs and implements a DSP based intelligent battery charger and residual capacity estimator. This system uses the proposed structure of the series circuit and battery equalizer with the intelligent fuzzy charge algorithm to charge batteries, and the improved coulometric measurement with accurate residual capacity estimation to estimate the residual capacity of batteries. Because of using the intelligent fuzzy charge algorithm can give different charging current depend on the difference of voltage, capacity and temperature of battery; And because of using the battery equalizer can adjust the voltage of battery. The charger can charge the battery safely without causing any damage. From the experimental results, the charger can achieve the purpose of fast and uniform charge with charging time six (6) to eight (8) hours, the residual capacity estimator can accurate estimate the residual capacity of batteries due to calculating the increment current and considering the aging factor.

This thesis is to design an intelligent battery charger and residual capacity estimator with DSP. This system uses the proposed structure of the series circuit and battery equalizer with the intelligent fuzzy charge algorithm to charge battery, The internal resistance measurement can accurately estimate the residual capacity of battery. Because of using the intelligent fuzzy charge algorithm, it can give different charging current depends on voltage, capacity and temperature of battery. Because of using battery equalizer, it can adjust the voltage of battery to guarantee the battery be charged safely. According to experimental results, the charger can achieve the goal of fast and uniform charge within 6 to 8 hours. On the residual capacity estimator, We measure internal resistance to accurately estimate residual capacity of battery, because internal resistance is affected by environmental temperature, battery corrosion, aging factor and output current .

This work presents design techniques for the implementation of high-speed analog integrated circuits for wireless and wireline communications systems. Limitations commonly found in high-speed switched-capacitor (SC) circuits used for intermediate frequency (IF) filters in wireless receivers are explored. A model to analyze the aliasing effects due to periodical non-uniform individual sampling, a technique used in high-Q high-speed SC filters, is presented along with practical expressions that estimate the power of the generated alias components. The results are verified through circuit simulation of a 10.7MHz bandpass SC filter in TSMC 0.35mu-m CMOS technology. Implications on the use of this technique on the design of IF filters are discussed. To improve the speed at which SC networks can operate, a continuous-time common-mode feedback (CMFB) with reduced loading capacitance is proposed. This increases the achievable gain-bandwidth product (GBW) of fully-differential ampli- fiers. The performance of the CMFB is demonstrated in the implementation of a second-order 10.7MHz bandpass SC filter and compared with that of an identical filter using the conventional switched-capacitor CMFB (SC-CMFB). The filter using the continuous-time CMFB reduces the error due to finite GBW and slew rate to less than 1% for clock frequencies up to 72MHz while providing a dynamic range of 59dB and a PSRR- > 22dB. The design of high-speed transversal equalizers for wireline transceivers requires the implementation of broadband delay lines. A delay line based on a third-order linear-phase filter is presented for the implementation of a fractionally-spaced 1Gb/s transversal equalizer. Two topologies for a broadband summing node which enable the placement of the parasitic poles at the output of the transversal equalizer beyond 650MHz are presented. Using these cells, a 5-tap 1Gb/s equalizer was implemented in TSMC 0.35mu-m CMOS technology. The results show a programmable frequency response able to compensate up to 25dB loss at 500MHz. The eye-pattern diagrams at 1Gb/s demonstrate the equalization of 15 meters and 23 meters of CAT5e twistedpair cable, with a vertical eye-opening improvement from 0% (before the equalizer) to 58% (after the equalizer) in the second case. The equalizer consumes 96mW and an area of 630mu-m x 490mu-m.

The object of this research is to develop a solution for band-limited channels. Backplane channels and GPON channels are investigated to apply an equalization technique. Different lengths of backplane channels are measured with different signal speeds to investigate the channel performance. Also a GPON system with different fiber lengths is designed and set up in a lab to measure the BER performance. The GPON system utilizes a Fabry-Perot laser for the most economical solution. After the circuits are fabricated, they are inserted into the system to measure the performance of the channels with equalizers. Both the backplane and the GPON system show successful channel improvement in measured eye diagrams and BER. To expedite the procedure and eventually build an adaptive system which could be inserted and self-optimizing, we found it essential to monitor the output of the equalizer. A novel analog way to achieve this goal is suggested. All the equalizers mentioned in this dissertation have one summing node to add up all the values from VGAs. This structure is very efficient, but in the event that there are too many VGAs, it draws too much current through the one node. This issue is dealt with by the design of two nine tap equalizers, which are compared to assess the difference in performance between the unbalanced structure and the balanced structure.

The advancements of semiconductor processing technology have led to the ability for computing platforms to operate on large amounts of data at very high clock speeds. To fully utilize this processing power the components must have data continually available for operation upon and transport to other system components. To enable this data requirement, high speed serial links have replaced slower parallel communication protocols. Serial interfaces inherently require fewer signals for communication and thus reduce the device pin count, area and cost. A serial communication interface can also be run at a higher frequency because the clock skew between channels is no longer an issue since the data transmitted on various channels is independent. Serial data transmission also comes with a set of drawbacks when signal integrity is considered. The data must propagate through a channel that induces unwanted effects onto the signals such as intersymbol interference. These channel effects must be understood and mitigated to successfully transmit data without creating bit errors upon reception at the target component. Previously developed adaptive equalization techniques have been used to filter the effects of intersymbol interference from the transmitted data in the signal. This report explores the modeling and implementation of a system comprised of a transmitter, channel, and receiver to understand how intersymbol interference can be removed through a decision-feedback equalizer realized in hardware. The equalizer design, implementation, and measurements are the main focus of this report and are based on previous works in the areas of integrated circuit testing, channel modeling, and equalizer design. Simulation results from a system modeled in Simulink are compared against the results from a hardware model implemented with an FPGA, analog to digital converter and discrete circuit elements. In both the software and hardware models, bit errors were eliminated for certain amounts of intersymbol interference when a receiver with decision-feedback equalization was used instead of a receiver without equalization. / text

At a communications receiver the observed signal is a corrupted version of the transmitted signal. This distortion in the received signal is due to the physical characteristics of the channel, including multipath propagation, the non-idealities of copper wires and impulse noise. Equalization is a process to combat these distortions in order to recover the original transmitted signal. Roughly stated, the equalizer tries to implement the inverse transfer function of the channel while taking into account the channel noise. The equalizer parameters can be tuned to this inverse transfer function using an adaptive algorithm. In many cases, the algorithm uses a training sequence to drive the equalizer parameters to the optimum solution. But, for time-varying channels or multiuser channels the use of a training sequence is inefficient in terms of bandwidth, as bandwidth is wasted due to the periodic re-transmission of the training sequence. A blind equalization algorithm is a practical method to eliminate this training sequence. An equalizer adapted using a blind algorithm is a key component of a bandwidth efficient receiver for broadcast and point-to-multipoint communications. The initial convergence performance of a blind adaptive equalizer depends on the higher-order statistics of the transmitted signal. In modern digital systems, Tomlinson-Harashima precoding (THP) is often used for signal shaping and to mitigate the error propagation problem of a decision feedback equalizer (DFE). The concept of THP comes from pre-equalization. In fact, it is a nonlinear form of pre-equalization, which bounds the higher-order statistics of the transmitted signal. But, THP and blind equalization are often viewed as incompatible equalization techniques. In this research, we give multiple scenarios where blind equalization of a THP-encoded signal might arise. With this motivation we set out to answer the question, can a blind equalizer successfully acquire a THP-encoded signal? We investigate the combination of a Tomlinson-Harashima precoder on the transmitter side and a blind equalizer on the receiver side. By bounding the kurtosis of the THP-encoded signal, we show that THP actually aids the initial convergence of blind equalization. We find that, as the symbol constellation size increases, the THP-encoded signal kurtosis approaches that of a uniform distribution, not a Gaussian. We investigate the compatibility of blind equalization with THP-encoded signals for both SISO and MIMO systems. In a SISO system, conventional blind algorithms can be used to counter the distortions introduced in the received signal. However, in a MIMO system with multiple users, the other users act as interferers on the desired user's signal. Hence, modified blind algorithms need to be applied to mitigate these interferers. For both SISO and MIMO systems, we show that the THP encoder ensures that the signal distribution approaches a non-Gaussian distribution. Using Monte Carlo simulations, we study the effects of Tomlinson-Harashima precoding on the performance of Bussgang-type blind algorithms and verify our theoretical analysis. The major contributions of this thesis are: • A demonstration that a blind equalizer can successfully acquire a THP-encoded signal for both SISO and MIMO systems. We show that THP actually aids blind equalization, as it ensures that the transmitted signal is non-Gaussian. • An analytical quantification of the effects of THP on the transmitted signal statistics. We derive a novel bound on the kurtosis of the THP-encoded signal. • An extension of the results from a single-user SISO scenario to multiple users and a MIMO scenario. We demonstrate that our bound and simulated results hold for these more general cases. Through our work, we have opened the way for a novel application of training sequence-less equalization: to acquire and equalize THP-encoded signals. Using our proposed system, periodic training sequences for a broadcast or point-to-multipoint system can be avoided, improving the bandwidth efficiency of the transceiver. Future modem designs with THP encoding can make use of our advances for bandwidth efficient communication systems.