International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / GLONASS is similar to GPS in many aspects such as system configuration, navigation mechanism, signal structure, etc.. There exists the possibility of receiving and processing GLONASS signals with GPS technology. The frequency plan of the GLONASS system is different from that of GPS. This makes the front-end of GLONASS receiver more complicated. The work here manifests our initial effort in GLONASS receiving. A design scheme is proposed of a C/A code GLONASS receiver.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / In this paper, a hybrid frequency division multiple access/code division multiple access (FDMA/CDMA) system in a Rician fading channel is described and analysis. The performance of the hybrid system is compared with a wideband CDMA system, which occupies the same total bandwidth. The results show that for DPSK modulation with a RIKE receiver, a hybrid system can have a greater capacity with a strong direct path component or a high signal to noise ratio (SNR). Otherwise, a wideband system remains optimal.

Rodrigues, A. B. Alocação de recursos de rádio para sistemas sc-fdma baseado em relaxamento e programação linear. 2016. 73 f. Dissertação (Mestrado em Engenharia Elétrica e da Computação) - Campus de Sobral, Universidade Federal do Ceará, Sobral, 2016. / Submitted by Programa de Pós-Graduação Engenharia Elétrica e de Computação (secretaria_ppgeec@sobral.ufc.br) on 2017-03-06T21:14:14Z No. of bitstreams: 1 2016_dis_abrodrigues.pdf: 1200876 bytes, checksum: 65bf4b1452b81c2dd6e5c26b0ab5bbc4 (MD5) / Approved for entry into archive by Ana Márcia Sousa (marciasousa@ufc.br) on 2017-03-07T11:23:43Z (GMT) No. of bitstreams: 1 2016_dis_abrodrigues.pdf: 1200876 bytes, checksum: 65bf4b1452b81c2dd6e5c26b0ab5bbc4 (MD5) / Made available in DSpace on 2017-03-07T11:23:43Z (GMT). No. of bitstreams: 1 2016_dis_abrodrigues.pdf: 1200876 bytes, checksum: 65bf4b1452b81c2dd6e5c26b0ab5bbc4 (MD5) Previous issue date: 2017-03 / In this work, we study the maximization problem of the sum of the weighted data rates in the wireless system’s uplink that uses SC-FDMA. The SC-FDMA multiple access scheme was adopted in the LTE uplink especially because it eases the power amplifier design in the mobile terminals. However, SC-FDMA presents an important restriction in radio resource allocation that is not present in OFDMA that was adopted in the LTE downlink: the resource adjacency or contiguity. With the resource adjacency constraint, the blocks of frequency resources assigned to each mobile terminal should be adjacent in the frequency domain. From the resource allocation point of view, this new constraint not only makes ineffective all previous resource allocation solutions proposed for OFDMA but also turns the problems even more harder in terms of computational complexity. In this work, we study the total data rate maximization problem in uplink SC-FDMA systems. Firstly, we discuss about the optimal solution of the problem that can be obtained through the use of integer optimization techniques. Motivated by the high computational complexity of this solution, we propose an alternative solution based on integer optimization relaxation and application of linear programming. The simulation results show that our proposed scheme is able to achieve the optimal solution in 55% (at least) of the simulations with a much lower computational complexity. For the cases where the solution obtained by continuous linear programming is not integer, the study proposes an algorithm that obtains an integer solution through rounding techniques. We also present a performance analysis comparing the algorithm developed with algorithms present in the literature. / Neste trabalho, estudamos o problema de maximização do somatório das taxas de dados ponderadas no enlace reverso de um sistema sem fio que emprega Single Carrier - Frequency Division Multiple Access (SC-FDMA). O esquema de múltiplo acesso SC-FDMA apresenta uma importante restrição quanto a alocação de recursos que não está presente em sistemas Orthogonal Frequency Division Multiple Access (OFDMA) (esquema utilizado no enlace direto de sistemas Long Term Evolution (LTE)): a contiguidade ou adjacência de blocos de recursos na frequência. A restrição de adjacência implica que a alocação dos blocos de recursos a cada terminal móvel deve ser feita de forma contígua na frequência. Na ótica de alocação de recursos em redes móveis, essa nova restrição não só inviabiliza o uso das soluções desenvolvidas para OFDMA encontradas na literatura, mas também torna o problema bem mais desafiador do ponto de vista matemático e computacional. Primeiramente, nós discutimos sobre a solução ótima desse problema que pode ser obtida através de programação inteira. Motivado pela alta complexidade computacional desta solução, propomos o uso de técnicas de relaxamento do problema de otimização inteiro e aplicação de programação linear (contínua). Através de simulações computacionais, demonstramos que o esquema proposto é capaz de encontrar a solução ótima em pelo menos 55% das simulações realizadas com uma complexidade computacional muito menor. Para os casos em que a solução obtida pela programação linear contínua não é inteira, o estudo propõe um algoritmo que obtém uma solução inteira através de técnicas de arredondamento. Apresentamos também uma análise de desempenho comparando o algoritmo desenvolvido com algoritmos presentes na literatura.

Interference dominated wireless communications systems are considered. Joint detection methods are applied to combat the negative effects of the temporal and spatial interference. However, practical joint detectors are not commonly used due to their high complexity. Therefore, there is a constant need to deliver reduced complexity solutions that approach substantial fraction of the channel capacity. In the first part of this thesis it is shown that simple transmission technique employing repetition coding and interleaving combined with interference cancellation is an asymptotically optimal processing strategy when high interference is experienced, for instance due to the relatively high ratio of the number of signals to the number of orthogonal dimensions. Surprisingly, strong, capacity achieving codes exhibit inferior performance and are not well suited for iterative interference cancellation due to their sharp threshold characteristics. Motivated by this observation partitioned modulation is introduced and applied to a multiuser spread spectrum system, which inherently encompasses a repetition coding mechanism. The detection of the resulting signals employs a parallel interference cancellation approach, where the repetition code exchanges information iteratively with the canceller. Precise signal-to-noise ratio evolution of the proposed receiver as a function of demodulation iterations is given. It is shown, that for equal received power system, partitioned demodulator outperforms linear minimum mean squared error processor at a fraction of complexity. This receiver processing for a wide range of parameters delivers estimates that coincide with the optimal processing based on exhaustive search. For unequal received signal powers these advantages are even more visible and for a particular exponential power allocation the proposed system reaches the capacity of the channel. The analytical investigations are verified using computer simulations. In the second part of this dissertation, multi-user MIMO systems compliant with 3GPP LTE standard are considered. Turbo near-far resistant interference cancellation receiver is proposed. It jointly removes multi-user, multi-antenna and inter-symbol interference and outperforms traditional demodulation/decoding method adopted in the LTE standard. Semi-analytical method of predicting the performance of this joint receiver for any system setup is outlined. This approach makes it possible to tune up the performance of the system without running extensive bit-error-rate simulations. / Communications

This thesis concerns the effect of phase noise (PHN) on multi-carrier systems such as OFDM and the detection of multi-carrier symbols affected by PHN. It is known that PHN causes mixing between sub-carriers resulting in inter-carrier interference (ICI) and rotates symbols on every sub-carrier by a certain angle called the common phase error (CPE). We explore how these two effects arise and show that these two effects are coupled to each other. We also note that higher order M-QAM constellations like 64-QAM are more sensitive to CPE than smaller constellations like 4-QAM. Based on our observations on CPE, we propose a blind CPE estimation algorithm. We then address the issue of ICI and propose a turbo receiver design to mitigate it.

This thesis concerns the effect of phase noise (PHN) on multi-carrier systems such as OFDM and the detection of multi-carrier symbols affected by PHN. It is known that PHN causes mixing between sub-carriers resulting in inter-carrier interference (ICI) and rotates symbols on every sub-carrier by a certain angle called the common phase error (CPE). We explore how these two effects arise and show that these two effects are coupled to each other. We also note that higher order M-QAM constellations like 64-QAM are more sensitive to CPE than smaller constellations like 4-QAM. Based on our observations on CPE, we propose a blind CPE estimation algorithm. We then address the issue of ICI and propose a turbo receiver design to mitigate it.

This master thesis investigates the uplink transmition from User Equipment (UE) to base station in LET (Long Term Evolution) and channel estimation using pilot symbols with parameter defined in 3GPP (3rd Generation Partnership Project) specifications. The purpose of the thesis was to implement a simulator which can generate uplink signal as it is generated by UE. The Third Generation (3G) mobile system was given the name LTE. This thesis focus on the uplink of LTE where single carrier frequency division multiple access (SC-FDMA) is utilized as a multiple access technique. The advantage over the orthogonal frequency division multiple access (OFDMA), which is used in downlink is to get better peak power characteristics. Because in uplink communication better peak power characteristic is necessary for better power efficiency in mobile terminals. To access the performance of uplink transmition realistic channel model for wireless communication system is essential. Channel models used are proposed by International Telecommunication Union (ITU) and the correct knowledge of these models is important for testing, optimization and performance improvements of signal processing algorithms. The channel estimation techniques used are Least Square (LS) and Least Minimum Mean Square Error (LMMSE) for different channel models. Performance of these algorithms has been measured in term of Bit Error Rate (BER) and Signal to Noise Ratio (SNR).

No description available.

Aim of thesis was to acquaint with architecture and process of signal in systems using broadband LTE wireless technology. Thesis in detail is described physical layer of system. Next there is described comparison of LTE and WiMAX and table with all present systems. Thesis also is contained information about tested LTE system in real traffic. Next aim was created simulation of LTE system in downlink and uplink. Interface was created for easier configuration of each characteristics of transfer and type of interference of useful signal. This interface is contained control of whole simulation and presentation of measured values. Measured data were processed into graphs, which show dependence of error rate BER on C/N of useful and interference signal.

Cette thèse est consacrée à l’étude de la modulation OFDM/OQAM en tant qu’alternative à la modulation OFDM. Nous traitons plus particulièrement le contexte multiusagers. De ce point de vue, les aspects de synchronisation sont déterminants. Les différentes options plus le choix de la forme d’onde sont donc examinés de ce point de vue. Un autre objectif est de montrer de manière précise comment la modulation OFDM/OQAM peut s’adapter à une transmission de type cellulaire, en prenant comme référence le système 3GPP/LTE. Les principales contributions que nous avons apportées sont : 1) Une analyse des phénomènes de désynchronisation : nous analysons l’effet de la désynchronisation, suivant les axes temporel et fréquentiel, sur les performances de l’OFDM/OQAM au récepteur. 2) Méthode de synchronisation : nous analysons une méthode de synchronisation temporelle définie dans un contexte de transmission OFDM/OQAM mono-usager et nous l’adaptons à un scénario de type multi-usagers. 3) Proposition d’un schéma d’accès multiple : nous proposons un schéma d’accès multiple basé sur la modulation OFDM/OQAM, alternatif aux techniques connues OFDMA et SC-FDMA, pour la transmission en liaison montante dans un contexte de type 3GPP/LTE. / This thesis is dedicated to the study of the OFDM/OQAM modulation as an alternative to the OFDM modulation. We treat more especially the multi-user environment. In this respect, synchronization aspects are crucial. The different options plus the choice of the waveform are examined in this point of view. Another objective is to precisely show how the OFDM/OQAM can be adapted to a cellular transmission type, taking as reference the 3GPP/LTE system. The main contributions we have made are : 1) Analysis of the desynchronization phenomena : we analyze the effect of desynchronization, according to the time and frequency axes, on the performance of OFDM/OQAM at the receiver side. 2) Synchronization method : we analyze a method of temporal synchronization defined in a single user OFDM/OQAM transmission and we adapt it to a multi-user scenario type. 3) Proposing for a multiple access scheme : we propose a multiple access scheme based on theOFDM/OQAM modulation, alternative to the known techniques OFDMA and SC-FDMA, for the UL transmission in a 3GPP/LTE context.