Initial Synchronization for 802.16e Downlink
ABSTRACT In this paper, we propose an initial synchronization scheme for time and carrier frequency synchronization and cell identification in 802.16e OFDMA downlink. The proposed method does not require knowledge of actual transmitted preamble, but only utilizes the preamble structure and inverse Fourier transform properties to obtain time/frequency synchronization. Through simulations, we show that the proposed synchronization method is suitable in multipath as well as multicell environment. Although evaluated for IEEE 802.16e, the proposed method can also be used in other OFDM systems with similar signal properties.
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- "When M is not divisible by the number of subcarriers, e.g., M = 3 for the downlink of IEEE 802.16 OFDMA (WiMAX) system, the training symbol is made up of highly correlated but not identical segments in the time domain. This scenario has not been investigated by the existing literature –, and Bhatt et al  suggested to use the cyclic prefix for frequency estimation. "
Conference Paper: A Universal Frequency Offset Estimator for OFDM Applications[Show abstract] [Hide abstract]
ABSTRACT: This paper studies fractional carrier frequency offset (CFO) estimation for orthogonal frequency-division multiplexing (OFDM) systems. In the IEEE 802.16 (WiMAX) standard, a training symbol structure with three highly correlated but not identical segments is specified. The existing CFO estimation methods require the segments in the training symbol to be identical, so cannot work for the generalized training structure. In this paper, we proposed a universal fractional CFO estimator to solve the problem. Both the analytical and numerical results are presented to confirm the performance of the proposed method.Global Telecommunications Conference, 2009. GLOBECOM 2009. IEEE; 01/2010
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- "Figure 2 depicts the preamble of segment 1 where subcarrier 0 will correspond to the first subcarrier used on the preamble symbol . Each preamble data is transmitted on every 3 rd subcarrier within the preamble symbol and the offset of the preamble subcarrier helps mobile or subscriber station determine sector of the cell . "
ABSTRACT: In wireless-domain, performance evaluation of preamble detection under varying channel conditions is of compelling research interest nowadays. Most of the existing works, based on preamble detection under channel conditions are limited to ITU, AWGN etc in Mobile WiMAX. In this work, we have performed preamble detection for 1024 point FFT and 512 point FFT data under SUI channel models in addition to ITU –R Vehicular A and Pedestrian B models. The results show that the performance of 1024 FFT is better than 512 FFT under various channel models. Moreover, we analyzed the behavior of various channels for these two different bandwidths.
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ABSTRACT: Embedded reconfigurable architectures are currently attracting increasing attention in the wireless communications industry due to the escalating number of wireless standards in today's market. Application specific instruction-set processors (ASIPs) present a reconfigurable solution that offers a compromise between programmability and low power consumption. In this article, the design and implementation of an embedded synchronization and acquisition ASIP for OFDM based systems is proposed. The engine architecture is presented and the programming model is explained in details. The proposed engine is scalable and it can be configured to support a multitude of synchronization algorithms and OFDM standards. While applicable to many OFDM systems, the proposed architecture was successfully verified on long term evolution (LTE Rel. 8) and WiMAX 802.16e systems. A partial list of synchronization and acquisition algorithms are tested on the engine for the two standards, and the results highlight the capabilities of the engine. The processor has been synthesized with 0.18μm standard cell CMOS library. It is estimated to occupy 1.1 mm2 and the projected power consumption is 7.9mW at 120 MHz, which meets the speed requirements of the tested standards. More results are included within the article.EURASIP Journal on Embedded Systems 01/2012; 2012(1). DOI:10.1186/1687-3963-2012-2