What is it about?

Initial ranging (IR) is a process of performing power adjustment, timing offset estimation, and synchronization between Base Station (BS) and all users. It plays a vital role in mobile WiMAX standard which establishes a communication link between BS and Ranging Subscriber Stations (RSSs) i.e. users. Since RSS is located far away from the BS and uplink signal is corrupted by noise, IR process becomes inferior. Thus, we propose Improved Dynamic Threshold based IR (IDTIR) method which is comprised of following three phases: (i) code detection phase, (ii) filtering phase, and (iii) parameter estimation phase. In first two phases, the received signal is pre-processed in order to eliminate noise and unselected codes from the codeset. Then, the noise-free signal is considered for final phase which has only selected codes which improves accuracy. New Weight based code detection method is employed for detecting code and Adaptive Filter (AF) is employed to remove unnecessary noise from the signal. Iterative Expectation Maximization (IEM) algorithm is involved in the estimation of channel coefficient and timing offset. All possible active paths are detected by setting a dynamic threshold value for each channel by the Enhanced Dynamic Threshold (EDT) method. For all active channels, Round Trip Delay (RTD), and power level are estimated by considering particular channel coefficient and timing offset. Extensive simulation of proposed work shows considerable improvements in performance.

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Why is it important?

Our work is of primary importance in wireless communication as effective synchronization is performed using an improved dynamic threshold based initial ranging process which reduces the interference thereby improving the performance of main tasks such as code detection, timing offset estimation, power estimation with minimum computational complexity.


While being a student, I always had a great interest in research areas pertaining to WiMAX, OFDMA ranging, Synchronization, etc., to mitigate the loss while communication. Now being Research Scholar I got an opportunity to work on these areas. As a result of which I got extensively improved results over synchronization. procedure. I hope other researchers benefit from my work and the results I achieved working in the same research area.

naveen kn
Dr. Ambedkar Institute of Technology

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This page is a summary of: A Novel Multi-Phase Initial Ranging Process for OFDMA Systems: An Improved dynamic Threshold Based Multi-user Detection Approach, IET Communications, May 2020, the Institution of Engineering and Technology (the IET), DOI: 10.1049/iet-com.2019.0936.
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