scispace - formally typeset
Search or ask a question
Proceedings ArticleDOI

On synchronization algorithms for OFDMA based wireless MAN system

14 May 2007-pp 515-519
TL;DR: In this paper, robust and efficient frame detection, symbol timing synchronization, frequency synchronization and cell ID detection techniques suitable for IEEE 802.16d/e wireless MAN system are proposed.
Abstract: In this paper, robust and efficient frame detection, symbol timing synchronization, frequency synchronization and cell ID detection techniques suitable for IEEE 802.16d/e wireless MAN system are proposed. The proposed timing synchronization algorithm exploits periodicity in preamble and also cyclic prefix (CP) periodicity to find the orthogonal frequency division multiplexing (OFDM) symbol boundary. This algorithm is a novel combination of preamble and CP self-correlation information to achieve symbol timing synchronization. The proposed frequency synchronization algorithm also uses self-correlation result of preamble and CP. Cell ID detection is done using the cross correlation properties of the preamble. The proposed synchronization algorithms can do synchronization even under low SNRs, high frequency offset, and multipath fading channels.
Citations
More filters
Patent
21 Dec 2007
TL;DR: In this article, a method for uplink synchronization in a wireless communication device with a base station in wireless communication system based on Orthogonal Frequency Division Multiple Access (OFDMA) is disclosed.
Abstract: A method for uplink synchronization, in a wireless communication device, with a base station in a wireless communication system based on Orthogonal Frequency Division Multiple Access (OFDMA) is disclosed The method comprises selecting (440), by the wireless communication device, at least one ranging slot randomly from ranging slots in at least a transition gap The wireless communication device further transmits (445) at least one ranging code in the selected at least one ranging slot

9 citations

Patent
10 Dec 2008
TL;DR: In this article, the authors proposed a preamble-based method for network coexistence in which a network communication method and a network device are used in order to identify the unknown terminal and connect it to an existing network.
Abstract: Provided are a network communication method and a network device using a preamble. According to the network communication method and the network device, network coexistence is easily achieved by using network identification transmitted in the preamble, and an unknown terminal, which has a low reception signal to noise ratio (SNR) and has not yet been connected to an existing network, is easily connected to the existing network.

5 citations

References
More filters
Book
31 Dec 1999
TL;DR: In this paper, the authors present a comprehensive introduction to OFDM for wireless broadband multimedia communications and provide design guidelines to maximize the benefits of this important new technology, including modulation and coding, synchronization, and channel estimation.
Abstract: From the Book: The manifestations of the mode of goodness can be experienced when all the gates of the body are illuminated by knowledge The Bhagavad Gita (14.11) During the joint supervision of a Master's thesis "The Peak-to-Average Power Ratio of OFDM," of Arnout de Wild from Delft University of Technology, The Netherlands, we realized that there was a shortage of technical information on orthogonal frequency division multiplexing (OFDM) in a single reference. Therefore, we decided to write a comprehensive introduction to OFDM. This is the first book to give a broad treatment to OFDM for mobile multimedia communications. Until now, no such book was available in the market. We have attempted to fill this gap in the literature. Currently, OFDM is of great interest by the researchers in the Universities and research laboratories all over the world. OFDM has already been accepted for the new wireless local area network standards from IEEE 802.11, High Performance Local Area Network type 2 (HIPERLAN/2) and Mobile Multimedia Access Communication (MMAC) Systems. Also, it is expected to be used for the wireless broadband multimedia communications. OFDM for Wireless Multimedia Communications is the first book to take a comprehensive look at OFDM, providing the design guidelines one needs to maximize benefits from this important new technology. The book gives engineers a solid base for assessing the performance of wireless OFDM systems. It describes the new OFDM-based wireless LAN standards; examines the basics of direct-sequence and frequency-hopping CDMA, helpful in understanding combinations of OFDM and CDMA. It also looks at applications of OFDM, includingdigital audio and video broadcasting, and wireless ATM. Loaded with essential figures and equations, it is a must-have for practicing communications engineers, researchers, academics, and students of communications technology. Chapter 1 presents a general introduction to wireless broadband multimedia communication systems (WBMCS), multipath propagation, and the history of OFDM. A part of this chapter is based on the contributions of Luis Correia from the Technical University of Lisbon, Portugal, Anand Raghawa Prasad from Lucent Technologies, and Hiroshi Harada from the Communications Research Laboratory, Ministry of Posts and Telecommunications, Yokosuka, Japan. Chapters 2 to 5 deal with the basic knowledge of OFDM including modulation and coding, synchronization, and channel estimation, that every post-graduate student as well as practicing engineers must learn. Chapter 2 contains contributions of Rob Kopmeiners from Lucent Technologies on the FFT design. Chapter 6 describes the peak-to-average power problem, as well as several solutions to it. It is partly based on the contribution of Arnout de Wild. Basic principles of CDMA are discussed in Chapter 7 to understand multi carrier CDMA and frequency-hopping OFDMA, which are described in Chapters 8 and 9. Chapter 8 is based on the research contributions from Shinsuke Hara from the University of Osaka, Japan, a postdoctoral student at Delft University of Technology during 1995-96, Chapter 9 is based on a UMTS proposal, with main contributions of Ralf Bohnke from Sony, Germany, David Bhatoolaul and Magnus Sandell from Lucent Technologies, Matthias Wahlquist from Telia Research, Sweden, and Jan-Jaap van de Beek from Lulea University, Sweden. Chapter 10 was written from the viewpoint of top technocrats from industries, government departments, and policy-making bodies. It describes several applications of OFDM, with the main focus on wireless ATM in the Magic WAND project, and the new wireless LAN standards for the 5 GHz band from IEEE 802.11, HIPERLAN/2 and MMAC. It is partly based on contributions from Geert Awater from Lucent Technologies, and Masahiro Morikura and Hitoshi Takanashi from NTT in Japan and California, respectively. We have tried our best to make each chapter quite complete in itself This book will help generate many new research problems and solutions for future mobile multimedia communications. We cannot claim that this book is errorless. Any remarks to improve the text and correct any errors would be highly appreciated.

4,020 citations

Journal ArticleDOI
TL;DR: A rapid synchronization method is presented for an orthogonal frequency-division multiplexing (OFDM) system using either a continuous transmission or a burst operation over a frequency-selective channel.
Abstract: A rapid synchronization method is presented for an orthogonal frequency-division multiplexing (OFDM) system using either a continuous transmission or a burst operation over a frequency-selective channel. The presence of a signal can be detected upon the receipt of just one training sequence of two symbols. The start of the frame and the beginning of the symbol can be found, and carrier frequency offsets of many subchannels spacings can be corrected. The algorithms operate near the Cramer-Rao lower bound for the variance of the frequency offset estimate, and the inherent averaging over many subcarriers allows acquisition at very low signal-to-noise ratios (SNRs).

3,492 citations

Journal ArticleDOI
TL;DR: It is shown, and confirmed by simulation, that to maintain signal-to-interference ratios of 20 dB or greater for the OFDM carriers, offset is limited to 4% or less of the intercarrier spacing.
Abstract: This paper discusses the effects of frequency offset on the performance of orthogonal frequency division multiplexing (OFDM) digital communications. The main problem with frequency offset is that it introduces interference among the multiplicity of carriers in the OFDM signal. It is shown, and confirmed by simulation, that to maintain signal-to-interference ratios of 20 dB or greater for the OFDM carriers, offset is limited to 4% or less of the intercarrier spacing. Next, the paper describes a technique to estimate frequency offset using a repeated data symbol. A maximum likelihood estimation (MLE) algorithm is derived and its performance computed and compared with simulation results. Since the intercarrier interference energy and signal energy both contribute coherently to the estimate, the algorithm generates extremely accurate estimates even when the offset is far too great to demodulate the data values. Also, the estimation error depends only on total symbol energy so it is insensitive to channel spreading and frequency selective fading. A strategy is described for initial acquisition in the event of uncertainty in the initial offset that exceeds 1/2 the carrier spacing, the limit of the MLE algorithm. >

2,475 citations

Proceedings ArticleDOI
25 Jul 1995
TL;DR: The authors present the MMSE and LS estimators and a method for modifications compromising between complexity and performance and the symbol error rate for a 18-QAM system is presented by means of simulation results.
Abstract: The use of multi-amplitude signaling schemes in wireless OFDM systems requires the tracking of the fading radio channel. The paper addresses channel estimation based on time-domain channel statistics. Using a general model for a slowly fading channel, the authors present the MMSE and LS estimators and a method for modifications compromising between complexity and performance. The symbol error rate for a 18-QAM system is presented by means of simulation results. Depending upon estimator complexity, up to 4 dB in SNR can be gained over the LS estimator.

1,647 citations

Journal ArticleDOI
TL;DR: The authors discuss the potential of OFDM signaling, with its limitations and inherent problems, as well as another potential technique that has so far been overlooked: single-carrier transmission with frequency- domain equalization, and introduces coded-OFDM (COFDM), which makes use of channel coding and frequency-domain interleaving.
Abstract: The authors discuss the potential of OFDM signaling, with its limitations and inherent problems, as well as another potential technique that has so far been overlooked: single-carrier transmission with frequency-domain equalization. The carrier synchronisation issue is dealt with before the authors introduce coded-OFDM (COFDM), which makes use of channel coding and frequency-domain interleaving. >

1,423 citations