• Journal of Information Processing Systems
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• v.15 no.4
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• pp.890-903
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• 2019

The single carrier frequency domain equalization (SC-FDE) technology is an important part of the broadband wireless access communication system, which can effectively combat the frequency selective fading in the wireless channel. In SC-FDE communication system, the accuracy of timing synchronization directly affects the performance of the SC-FDE system. In this paper, on the basis of Schmidl timing synchronization algorithm a timing synchronization algorithm suitable for FPGA (field programmable gate array) implementation is proposed. In the FPGA implementation of the timing synchronization algorithm, the sliding window accumulation, quantization processing and amplitude reduction techniques are adopted to reduce the complexity in the implementation of FPGA. The simulation results show that the algorithm can effectively realize the timing synchronization function under the condition of reducing computational complexity and hardware overhead.

• The KIPS Transactions:PartC
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• v.18C no.2
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• pp.119-126
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• 2011

In wireless sensor networks Time synchronization used to be performed after routing tree is constructed. It results in increasing the number of packets and energy consumption. In this paper, we propose a time synchronization algorithm combined with flooding routing tree construction algorithm, which applies LTS (Lightweight Time Synchronization) information packed into the forwarding and backward routing packets. Furthermore, the proposed algorithm compensates the time error due to clock drift using the round time with fixed period. We prove that the proposed algorithm could synchronize the time of among sensor nodes more accurately compared to TSRA (Time Synchronization Routing Algorithm) using NS2 simulation tool.

• Journal of information and communication convergence engineering
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• v.16 no.2
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• pp.84-92
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• 2018

For large wireless sensor networks running on battery power, the time synchronization of all sensor nodes is becoming a crucial task for waking up sensor nodes with exact timing and controlling transmission and reception timing. However, as network size increases, this synchronization process tends to require long processing time consume significant power. Furthermore, a naïve synchronization scheduler may leave some nodes unsynchronized. This paper proposes a power-efficient scheduling algorithm for time synchronization utilizing the notion of density, which is defined by the number of neighboring nodes within wireless range. The proposed scheduling algorithm elects a sequence of minimal reference nodes that can complete the synchronization with the smallest possible number of hops and lowest possible power consumption. Additionally, it ensures coverage of all sensor nodes utilizing a two-pass synchronization scheduling process. We implemented the proposed synchronization algorithm in a network simulator. Extensive simulation results demonstrate that the proposed algorithm can reduce the power consumption required for the periodic synchronization process by up to 40% for large sensor networks compared to a simplistic multi-hop synchronization method.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.29B no.10
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• pp.1-9
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• 1992

This paper presents an effective synchronization algorithm. It is different from the existing synchronization methods by inserting appropriate synchronization instructions between statements according to different kinds of data dependencies. The overhead caused by too many synchronization instructions in a loop can be a critical problem. Synchronization optimization is a method which discriminates and eliminates the redundant synchronization instructions in a loop. In this paper, a new synchronization optimization algorithm is developed, and performance analysis using simulation on the UNIX operating system is carried out.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.06a
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• pp.246-251
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• 1998

The basic requirement of a distributed multimedia system are intramedia synchronization which asks the strict delay and jitter for the check period of media buffer and the scaling duration with periodic continuous media such as audio and video media, and intermedia synchronization that needs the constraint for relative time relations among them when several media are presented in parallel. In this paper, a distributed multimedia synchronization algorithm based on the fuzzy logic is presented and the performance is evaluated through simulation. Intramedia synchronisation algorithm uses the media scaling techniques and intermedia synchronization algorithm uses variable service rates on the basis of fuzzy logic to solve the multimedia synchronization problem.

• ETRI Journal
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• v.37 no.5
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• pp.940-944
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• 2015

We present a frame synchronization algorithm for lowdensity parity-check (LDPC) coded burst transmissions, which combines a conventional pilots-assisted frame synchronization algorithm and a code-aided algorithm based on the mean magnitude of the soft outputs from the LDPC decoder. With moderate computational complexity, the proposed algorithm is more efficient in bandwidth than conventional pilots-assisted algorithms. When compared with other code-aided algorithms, the proposed algorithm offers a better trade-off between complexity and performance. Simulation results in the case of an 8-PSK system with (1944, 972) LDPC code show that the proposed algorithm can achieve a performance equivalent to that of the perfect frame synchronization, with a bandwidth efficiency loss of 0.06 dB due to the use of pilot symbols.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.415-417
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• 2005

Core operations (e.9. TDMA scheduler, synchronized sleep period, data aggregation) of many proposed protocols for different layer of sensor network necessitate clock synchronization. Our Paper mingles the scheme of dynamic clustering and diffusion based asynchronous averaging algorithm for clock synchronization in sensor network. Our proposed algorithm takes the advantage of dynamic clustering and then applies asynchronous averaging algorithm for synchronization to reduce number of rounds and operations required for converging time which in turn save energy significantly than energy required in diffusion based asynchronous averaging algorithm.

• The KIPS Transactions:PartC
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• v.18C no.1
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• pp.15-22
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• 2011

Usually time synchronization is performed after routing tree is constructed. This thesis proposes a time synchronization algorithm combined with single-flooding routing tree construction algorithm in a single path. TSRA (Time Synchronization Routing Algorithm) uses routing packets to construct a routing tree. Two types of time information are added to the routing packet: one is the packet receiving time, and the other is the packet sending time. Time offset and transmission time-delay between parent node and child node could be retrieved from the added time information using LTS (Lightweight Time Synchronization) algorithm. Then parent node sends the time offset and transmission time to children nodes and children nodes can synchronize their time to the parent node time along the routing tree. The performance of proposed algorithm is compared to the TPSN (Timing-sync Protocol for Sensor Networks) which is known to have high accuracy using NS2 simulation tool. The simulation result shows that the accuracy of time synchronization is comparable to TPSN, the synchronization time of all sensor nodes is faster than TPSN, and the energy consumption is less than TPSN.

• Journal of KIISE:Databases
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• v.34 no.4
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• pp.357-368
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• 2007

This paper proposes the SAMD(Synchronization Algorithms based on Message Digest) algorithm based on message digest in order to data synchronization between a database server and a mobile database. The SAMD algorithm makes the images at the database server and the mobile database using message digest tables and compares two images in order to select the rows needed to synchronization. If two images are different, the synchronization is progressed according to synchronization policy. The SAMD algorithm does not use techniques which are dependent the some database vendor and also triggers, stored procedures and timestamps. The SAMD only uses the standard SQL functions for the synchronization. Therefore the SAMD algorithm is used in any combinations of the database server and the mobile database because the SAMD algorithm is not depended on some database venders. Also the SAMD algorithm shows better performance compared with existing synchronization products.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.8
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• pp.488-490
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• 2014

This paper deals with distributed time and frequency synchronization algorithms using the flocking technique for OFDMA-based wireless mesh networks. We propose a time and frequency synchronization model taking into account channel propagation delays existing in wireless mesh networks, and analyze the convergence condition of the proposed synchronization algorithm. Convergence performance of the proposed synchronization algorithm is analyzed via computer simulation in terms of synchronization parameters in the time and frequency synchronization model.