An efficient synchronization signal structure for OFDM-based cellular systems

Abstract

OFDM has been a widely accepted technology in high rate and multimedia data service systems such as long term evolution (LTE) in the 3rd generation partnership project (3GPP). In this paper, we investigate a synchronization signal structure and corresponding cell search algorithm in the LTE system where two, primary and secondary synchronization signals are employed. We focus on the secondary synchronization signal which possesses two layered scrambling sequences in addition to basic sequences. These scrambling sequences minimize performance degradation in cell search, but incur a high complexity to a mobile station receiver. In this paper, we propose a new secondary synchronization signal structure which does not require additional scrambling sequences while maintaining almost the same performance as the current LTE scheme. We evaluate the performance of the proposed scheme under various channel environments by examining the impacts of multipath fading, frequency offset, and vehicular speed. We also compare the complexity of the proposed scheme with the LTE scheme.

Behavior and Techniques for Improving Performance of OFDM Systems for Wireless communications

“…A number of techniques have been proposed for estimating and mitigating the CFO. These techniques are divided into 2 categories namely: a) Named Data Aided techniques: These techniques are based on the preamble blocks in the time domain or on the pilot sub-channels inserted at different OFDM blocks [78][79][80][81][82][83][84][85][86].Recently, Salim et.al [86] has proposed an iterative pilot-aided algorithm based on Expectation Conditional Maximization (ECM) for joint estimation of multipath channels, Wiener PHNs, and CFOs in Amplify-and-Forward (AF) based cooperative OFDM systems.The proposed estimator is found to be computationally efficient because it estimates the desired parameters in few iterations and have high SNR. The pilots, training sequences or preambles are basically inserted at the transmitter in order to assist the synchronization at the receiving end [87].…”

Hierarchical taylor-made scheduling for data traffic with prioritization over LTE networks

“…Proportional Fairness [17] is the most commonly used technique [18]. It seeks to attend the compromise between maximizing the overall data throughput and enable a minimum level of service for all users.…”

Frequency Synchronization in OFDM System

“…The power level of the ternary sequence to be added needs to be low enough in order not to affect the normal operation of the OFDM system. Ilgyu Kim et al [14] proposed an efficient synchronization signal structure for OFDM-based Cellular Systems The sequence used for the Primary Synchronization signal is generated from a frequencydomain ZC sequence for high rate and multimedia data service systems such as LTE in the 3GPP. Ji-Woong Choi et al [15] described the joint ML estimation using correlation of any pair of repetition patterns, providing optimized performance.…”

“…Ec is the energy of subcarrier All the preamble based frequency offset estimation methods given in literature aims at accuracy and increasing the range of frequency offset estimation [2][3][4][5][6][7][8]. The importance of frequency offset estimation in various high speed broadband wireless applications can be understood from the literature in [11][12][13][14][15]. This paper deals with frequency offset estimation using ZC sequence as preamble.…”

“…6) r 1 (k) represents the received preamble compensated using Schmidl's algorithm if offset is within the range of ±1 and is given as in (14)    2…”