• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.9
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• pp.741-749
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• 2012

Ad Hoc Self-Organizing TDMA (ASO-TDMA) has been proposed as a specification to support the multi-hop data communication service for ships over VHF band. It allows for organizing a multi-hop ad-hoc network in a distributed manner by sharing the radio resources among the ships navigating along the route. In this paper, Markov chain analysis is given to provide the average throughput performance for ASO-TDMA protocol Furthermore, the analytical results are verified with computer simulation, which shows that there exists the optimal transmission rate to maximize the average throughput as the subframe size and the number of ships are varying in each hop region.

• Journal of Satellite, Information and Communications
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• v.10 no.4
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• pp.32-38
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• 2015

Next generation military satellite communication systems have been developed for expanding capacity and survivability. As for expanding capacity, the communication systems require efficient techonology to use limited resource. So, next generation communication systems are expected to use MF-TDMA technology. MF-TDMA is the technology which has the advantages of FDMA and TDMA. By using MF-TDMA, communication systems can use limited resource efficiently, and the performance of resource allocation depends on the allocation scheme. In this paper, we propose efficient allocation scheme for next generation military satellite communication systems. Also, we compare and analze performances such as Total Resource Efficient, Reject Ratio, Computational Time, PSD distribution with existing allocation schemes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4C
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• pp.364-370
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• 2006

It is required for correct signal detection to accurately maintain the synchronization of frequency and timing in a TDMA system. In this paper, we consider nondecision-aided estimation of frequency offset for the transmission of QPSK signal in a TDMA-based satellite system. The proposed scheme estimates the phases of two parts in the burst and then estimates the frequency offset based on the difference between the two estimated phases. Thus, it can provides performance comparable to that of conventional schemes, while significantly reducing the implementation complexity, The performance of the proposed scheme is analyzed and verified by computer simulation, when applied to a GSM based geostationary earth orbit mobile radio(GMR) system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1457-1467
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• 2015

Depending on the type of Tx-Rx pairs, VHF Data Exchange System (VDES) for maritime communication is expected to employ the different frequency channels. Load imbalance between the different channels turns out to be a critical problem for the multi-hop communication using Ad-hoc Self-Organizing TDMA (ASO-TDMA) MAC protocol, which has been proposed to provide the connectivity between land station and remote ship stations. In order to handle the inter-channel load imbalance problem, we consider a model of the stochastic geomety in this paper. After analyzing the spatial reuse efficiency in each hop region by the given model, we show that the resource utility can be maximized by balancing the inter-channel traffic load with optimal resource allocation in each hop region.

• Journal of the Korea Society of Computer and Information
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• v.17 no.3
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• pp.85-93
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• 2012

In this paper, I designed the satellite system, using the MF-TDMA (Multi Frequency-Time Division Multiple Access) DAMA (Demand-Assigned Multiple Access) method, that allocates the satellite resources more effectively to prevent a large quantity data discard when Earth Terminals (ETs) request their satellite network resource to Network Controller (NC) by using their history information, such as traffic pattern or traffic class which have been receiving, and the network controller allocates the satellite network resource and send to earth terminals by using his history information that earth terminals have been requested already. The U.S. Military Warfighter Information Network-Tactical (WIN-T) community has selected the L-3 Linkabit MF-TDMA DAMA Network Centric Waveform (NCW) as the networking standard for full-mesh IP over SHF satellite communications. In the MF-TDMA DAMA satellite network, network controller allocates the satellite network resources and enables maximum 255 earth terminals to communicate each other for periodic satellite network resource requests of earth terminals.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11B
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• pp.1640-1650
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• 2010

To prepare for the network centric warfare, Korea Joint Tactical Data Link System(KJTDLS) has been developed by the South Korean military recently and its development is divided into two phases: basic and complete ones. Due to the limited bandwidth and low transmission efficiency of the developing KJTDLS (basic), lots of problems could be occurred when the TDMA protocol in Link-16 is applied. In this paper, a new dynamic TDMA frame structure for KJTDLS(basic) is proposed and the performance of the proposed is evaluated through the implementation of simulation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.2
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• pp.511-527
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• 2024

This paper proposes a block-based self-organizing time-division multiple access (BSO-TDMA) protocol for very high frequency (VHF) data exchange system (VDES) in shipborne ad-hoc networks (SANETs). The BSO-TDMA reduces the collisions caused by the simultaneous transmission of automatic identification system (AIS) messages by uniformly allocating channel resources using a block-wise frame. For this purpose, the BSO-TDMA includes two functional operations: (1) frame configuration and (2) slot allocation. The first operation consists of block division and block selection. A frame is divided into multiple blocks, each consisting of fixed-size subblocks, by using the reporting interval (RI) of the ship. Then, the ship selects one of the subblocks within a block by considering the number of occupied slots for each subblock. The second operation allocates the slots within the selected subblock for transmitting AIS messages. First, one of the unoccupied slots within the selected subblock is allocated for the periodic transmission of position reports. Next, to transmit various types of AIS messages, an unoccupied slot is randomly selected from candidate slots located around the previously allocated slot. Experimental simulations are conducted to evaluate the performance of BSO-TDMA. The results show that BSO-TDMA has better performance than that of the existing SOTDMA.

• Journal of Advanced Navigation Technology
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• v.13 no.3
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• pp.406-411
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• 2009

In this paper, we study the method of noise analysis for analysing TDMA noise in a GSM mobile phone and describe the cause of TDMA noise. And we reduced noise by 9dB, 3.5dB, 6dB, using MIC shielding, equipped bead or capacitance, connected PCB ground based on the difference analysis method, which is one of common noise analysis methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.5B
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• pp.466-474
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• 2003

In this paper, we develope the simulation model for Ethernet passive optical networks (Ethernet-PON) by using OPNET. Ethernet-PON is an emerging access network technology that provides a low-cost method of deploying optical access lines. The simulator uses a Request/Grant TDMA MAC protocol based on IEEE 802.3ah EFM. It also executes registration, ranging and dynamic bandwidth allocation algorithm by exchanging control packets between OLT and ONUs. We have evaluated for success ratio of initial registration process and delay of late registration process. We also have simulated for dynamic TDMA protocol and static TDMA protocol in terms of channel utilization and queueing delay. We expect that this simulator can help to determine various parameters which are considered for designing Ethernet-PON system.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.6
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• pp.1025-1032
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• 2022

In this paper, the TDMA-based PoE wireless multi-IP camera transmission system using wireless communication technology is developed to reduce the burden of construction costs caused by the existing wired-based CCTV surveillance system and IP camera system. It intends to design and implement the long-distance wireless transmission technology of video. The transmission/reception prototype of the line IP transmission system and the wireless multi-IP camera transmission terminal and image acquisition device (SB-200) for the proposed related technology were described.