• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.7
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• pp.1272-1281
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• 1994

CDMA technique has been largely focused for Wireless Data Network and PCN. ALOHA protocol also has been proven to be effective for Packet Radio Network regardless of low throughput due to channel colisions. In this paper, we evaluate the performance of CDMA_ALOHA scheme, denoted as S_CDMA_ALOHA(Soltted_CDAM_ALOHA) and MS_CDMA_ALOHA(Minislotted_CDMA_ALOHA) system, by analytic and simulation method. The superiority of the CDMA_ALOHA systems over conventional Slotted ALOHA system are clearely demonstrated for throughput, delay and stability performances. The MS_CDMA_ALOHA scheme provides better delay and throughput performance than the S_CDMA_ALOHA scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.9A
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• pp.814-821
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• 2005

When there are many tags using the same frequency around the reader in RFID system, they disturb each other and in the end their response cannot be received by the reader. To solve this disturbance and fast identify the tags, the anti-collision algorithm, which is the core technology in RFID system, is needed. We propose two ALOHA-type Dynamic Framed Slotted ALOHA(DFS-ALOHA) algorithms using Dynamic Slot Allocation(DSA), which dynamically allocates the frame size in accordance with the number of tags and Tag Estimation Method(TEM), which estimates the number of tags around the reader. We also compare the performance of the proposed DFS-ALOHA algorithms with that of the conventional Framed Slotted ALOHA (FS-ALOHA) algorithms and the algorithms proposed by Vogt using OPNET simulation. According to the analysis, the two proposed DFS-ALOHA algorithms(DFS-ALOHA I and DFS-ALOHA II) show better performance than the conventional ALOHA-based algorithms regardless of the number of tags. Although the two proposed DFS-ALOHA algorithms show the similar performance, BFS-ALOHA ll is better because it is easier to be implemented in the system and the complexity is lower.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.3
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• pp.713-720
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• 1996

In recent, the demand of mobile communication system is increasing rapidly. However, since wireless resources is limitted, the protocol to utilize wireless resource efficiently is needed. Up to now, Slotted CDMA_ALOHA(S_CDMA_ALOHA) and Mini-Slotted CDMA_ALOHA(MS_CDMA_ALOHA) methods are proposed as a CDMA_ALOHA mechanism, and it is turned out that MS_CDMA_ALOHA offers betterperformance than S_CDMA_ALOHA mechanism. Also, IS-95 multiple access mechanism has been proposed as common air interface(CAI) protocol of CDMA digital cellular system. However, in former study, the performance evaluations were made without considertion of chnnel characteristics of wireless communication environment. In this paper, a new access mechanism for improring the performance in the DS/CDMA digital cellular environment is suggested. This mechanism is adaptive to the channel condition and based on the conventional MS_CDMA_ALOHA mechanism. Also, the performance of new access mechanism is compared with that of conventional mechanisms, through computer simulation. According tot h simulation results, it is shown that the proposed NA_CDMA_ALOHA(Noise-Adaptation CDMA_ALOHA) mechanism offers better performance than conventional three CDMA_ALOHA mechanisms in view of mean delay time and system throughput characteristics. This phenomenon is due to the fast that NA_CDMA_ALOHA mechanism controls the access attempts efficiently based on the channel condition in heavy traffic environments.

• The Transactions of the Korea Information Processing Society
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• v.1 no.4
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• pp.502-510
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• 1994

CDMA technique has been largely focused for Wireless Data Communication and Personal Communication Network. ALOHA protocol also has been proven to be effective for Packet Radio Radio Network regardless of low throughput due to channel collisions. In this paper, we evaluate the performance of MS-CDMA-ALOHA (Mini-Slotted-CDMA-ALOHA) system, by analytic and simulation method. The superiority of the MS-CDMA-ALOHA system over conventional Slotted ALOHA and Slotted-CDMA-ALOHA systems are clearly demonstrated for throughput, delay and stability performances.

• International journal of advanced smart convergence
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• v.12 no.4
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• pp.55-62
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• 2023

Slotted-Aloha (S-Aloha) has been widely employed in random access networks owing to its simple implementation in a distributed manner. To enhance the throughput performance of the S-Aloha, connection-based slotted-Aloha (CS-Aloha) has been proposed in recent years. The fundamental principle of the CS-Aloha is to establish a connection with a short-sized request packet before transmitting data packets. Subsequently, the connected node transmits long-sized data packets in a batch of size M. This approach efficiently reduces collisions, resulting in improved throughput compared to the S-Aloha, particularly for a large M. In this paper, we address the short-term fairness of the CS-Aloha, as quantified by Jain's fairness index. Specifically, we evaluate how equitably the CS-Aloha allocatestime slots to all nodes in the network within a finite time interval. Through simulation studies, we identify the impact of system parameters on the short-term fairness of the CS-Aloha and propose an optimal transmission probability to support short-term fairness.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.594-599
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• 2003

This paper proposed to compare and analyze the data throughput of ALOHA and Slotted-ALOHA method which were used to the communication of satellites in an early stage and apply to the data throughput of a transponder in an RFID system. The ALOHA method is the operation priority to a transponder but the Slotted ALOHA method is the operation priority to an reader in an RFID system. Because ALOHA method transmits the data to an reader as a authority of a transponder at random time when generating collisions, therefore, it seems reasonable to conclude that ALOHA method is inefficient for the data throughput and the efficiency of collision interval than Slotted-ALOHA method that synchronizes and controls the transponder in an reader.

• Journal of the Korea Fashion and Costume Design Association
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• v.9 no.2
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• pp.59-68
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• 2007

"Aloha" is the Hawaiian word that extends the warmth friendliness, and pride of the Hawaiian people to their island's visitors. The aloha shirt truly symbolizes aloha sprit to islanders and visitors alike. The earliest foreign settlers in the Hawaiian Islands were the Chinese and Japanese. They brought with them their myriad talents and trades, among them the art of tailoring. In July of 1936, a shirtmaker named Ellery J.Chun coined the term "Aloha Shirt" an apt characterization for such an eloquent garment. He was the first to make the shirt on a commercial basis. The shirt sold for as little as a dollar in Chun's own King-Smith store. The genuine aloha shirt is now regaled as a work of art and avidly sought out by collectors. When tourism came to Hawaii in the late 1930s, these unusal shirts were among the first thing that visitors had to have. Local designers and tailors worked quickly to meet the demand and began to expand the range of decoration to include palm trees and romantic beaches, tropical jungles and volcanoes, exotic flowers and scenes from polynesian legend. Therefore the aloha shirt had been born. The functional use of creative colors and amazing artistic renderings in these shirts certainly capture the simplicity and sprit of Hawaii. Aloha shirt is dress that display mystery and charm of Hawaii and cultural symbol of condensed Hawaiian mind. Furthermore, the innocence with which Hawaiians formerly translated their life and heritage onto fabric ranks these shirts with the finest of American folk art. Aloha shirt is made from cotton, silk, rayon in present and past. Most important design element of Aloha shirt is print pattern. Main print pattern of Aloha shirt are all over pattern, horizontal pattern, border pattern, Japanese pattern, picture pattern and back panel pattern. In this study I investigate the design characteristics and development process of aloha shirt.

• International Journal of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.43-51
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• 2023

Slotted ALOHA (S-ALOHA) is a classical medium access control protocol widely used in multiple access communication networks, supporting distributed random access without the need for a central controller. Although stability and delay have been extensively studied in existing works, most of these studies have assumed ideal channel conditions or independent fading, and the impact of time-correlated wireless channels has been less addressed. In this paper, we investigate the queueing delay performance in S-ALOHA networks under time-correlated channel conditions by utilizing a Gilbert-Elliott model. Through simulation studies, we demonstrate how temporal correlation in the wireless channel affects the queueing delay performance. We find that stronger temporal correlation leads to increased variability in queue length, a larger probability of having queue overflows, and higher congestion levels in the S-ALOHA network. Consequently, there is an increase in the average queueing delay, even under a light traffic load. With these findings, we provide valuable insights into the queueing delay performance of S-ALOHA networks, supplementing the existing understanding of delay in S-ALOHA networks.

• Proceedings of the IEEK Conference
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• summer
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• pp.5-9
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• 2004

This paper proposed a systematic analysis for slotted ALOHA with capture effect. This is a generalization for slotted ALOHA system. Based on this model, we can increase the maximum through-put of slotted ALOHA system with two power levels. Lee's algorithm is consider to be an extension of ALOHA system with capture effect. In this paper, we showed that, the choice of Lee's algorithm is not an optimum one. Based on the previous experimental results, we proposed here a more practical analysis for slotted ALOHA system. The result is very accurate and can be applied to other wireless systems which also employed capture effect.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.12
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• pp.4324-4342
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• 2014

Previous papers analyzed the throughput performance of the CDMA ALOHA system in Rayleigh fading channel, but they assume that the channel coefficient of Rayleigh fading was the same in the whole packet, which is not realistic. We recently proposed the finite-state Markov channel (FSMC) model to the throughput analysis of DS uncoded CDMA/unslotted ALOHA networks for fixed length data traffic in the mobile environment. We now propose the FSMC model to the throughput analysis of coded DS CDMA/unslotted ALOHA networks with variable length data traffic and one or two user classes in the mobile environment. The proposed DS CDMA/unslotted ALOHA wireless networks for two user classes with access control can maintain maximum throughput for the high priority user class under high message arrival per packet duration.