• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.3
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• pp.451-458
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• 2015

The deployment density of AP increases as well as the density WLAN stations due to increase of WLAN use and the real performance of WLAN is degraded. To improve the performance, there are many PHY/MAC technologies and OFDMA and full duplex are promising technologies among them. In conventional OFDMA WLAN MAC relate works, there are some limitations in terms of channel utilization and collision probability. Thus, it need to research for effective channel allocation protocol. Full duplex can transmit data on the same time and same frequency resource so it can allocate channel more flexible than half duplex. In this paper, we prose the OFDMA FD-MAC(Full Duplex MAC) protocol that it allocates the sub-channels based on the idle channel information for full duplex pair. In addition, it shows the throughput improvement by performance analysis.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06a
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• pp.369-372
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• 2011

최근 스마트폰 사용의 증가로 인해 지그비 네트워크는 동일한 주파수 대역을 사용하는 무선랜에 의한 간섭이 심각해졌다. 이와 같이 이기종 네트워크에 의해 발생하는 간섭 문제를 해결하기 위한 채널 호핑 기법의 연구가 활발히 이루어지고 있다. 본 논문에서는 자원 낭비와 패킷 손실을 최소화하기 위해 테이블 기반의 채널 호핑 기법을 제안한다. 제안한 테이블 기반의 채널 호핑 기법은 간섭의 발생을 채널 테이블을 통해 관리하며 이를 기반으로 채널 호핑을 수행한다. 기존 기법과의 성능 비교 실험을 통해 테이블 기반 채널 호핑 기법은 간섭 발생시 빠른 회피가 가능하고 이로 인해 네트워크의 성능을 향상시킬 수 있음을 확인하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.3
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• pp.534-541
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• 2018

The number of stations existing in the same wireless channel is increasing due to the spread of the wireless LAN devices. CSMA/CA, a conventional wireless LAN protocol, uses a random backoff method. In the random backoff scheme, collision between stations is frequent in a dense region where the number of stations existing in the same channel is several tens or more, and the performance of the performance degradation of such a protocol, the IEEE 802.11ah standard proposed a Restricted Access Window(RAW) wireless access method. RAW improves performance by limiting the number of concurrent access stations by dividing the stations into several groups. In this paper, we propose a method to improve the performance of channel connection by using new group creation, group removal and group relocation algorithm according to traffic change by improving existing RAW method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.5
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• pp.646-651
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• 2012

This paper is about the experiment which is throughput of WLANs based on 802.11 due to interference each other. Recently, WLAN has been increased due to generalization of smart-phone and potable notebook. Therefore, the decrease of throughput because of interference between WLANs is expected. In regard of this, the throughput of WLANs according to channelling is measured in order to figure out efficient channelling and the throughput of WLANs according to the number of AP was measured in order to get relation between number of AP and throughput. Then, more efficient channelling of 1, 5, 9, 13 is suggested and the throughput of WLAN is decreased as increasing of number of AP.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.255-258
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• 2002

무선 랜 서비스는 전송 선로에 대한 제약이 적으므로 높은 이동성을 보장하지만 무선이라는 망 자체의 특성에 의해 여러 가지 제약을 갖게 된다. 본 논문에서는 고속의 통신 속도 제공의 어려움, 에러의 빈도가 높은 불안정한 통신 채널, 저전력 소비등의 해결과 같은 문제를 가지는 무선 랜의 제한적인 요소들에 의해 비디오 스트리밍이 어떠한 영향을 받는지를 분석한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.11
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• pp.2188-2195
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• 2015

In tactical wireless local area networks, jamming attack can easily occur by sending out continuous radio signals. The damage will be serious when the channel frequency is identical. Since wireless channel environment is open to everyone, the perfect solution for jamming attack does not exist. However, a channel-hopping scheme is well known for mitigating those jamming attacks. In this paper, I consider various channel-hopping schemes in order to analyze the throughput and fairness performance under smart jammer attack. Also an analytical model is introduced to evaluate the throughput performances of channel-hopping schemes. After analyzing well known channel-hopping schemes, I propose a simple channel-hopping scheme that can enhance fairness significantly at minimal throughput degradation expense.

• Journal of Advanced Navigation Technology
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• v.23 no.6
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• pp.589-596
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• 2019

With the proliferation of intelligent transportation system (ITS) with dedicated short-range communication (DSRC) deployment, there are various applications requiring different throughput and reliability performance. To meet the enhanced throughput requirements in newly generated applications, IEEE 802.11bd is proposed to standardize for support of enhanced throughput and latency, preserving the fairness with previously deployed WLAN V2X devices. One of the main features of IEEE 802.11 bd is 20 MHz transmission to support the high data rate. In this paper, the primary channel selection method is proposed to guarantee the fairness with frame transmissions with 10 MHz bandwith including communications in WLAN V2X devices deployed with IEEE 802.11p. Simulation shows that the proposed channel access method for 20 MHz transmission with primary selection preserves the fairness without the change of channel access method in wide-band transmission.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.6
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• pp.85-96
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• 2003

Wireless LAM in itself is vulnerable to eavesdropping and modification attack, and thus, IEEE 802.11i and IEEE 802. 1x/1aa have been defined to secure the wireless channel. These protocols accompanied by RADIUS and EAP-TLS provide users of wireless LAM with integrity and confidentiality services, and also they perform authentication and access control of wireless ports. In this paper, we suggest a method to implement accounting session using authentication session of IEEE 802. 1x and accounting state machine is designed with the accounting session. Also, we propose a key exchange mechanism to establish secure channel between stations and an access point. The mechanism is designed to be inter-operable with IEEE 802. 1aa.

• Journal of KIISE:Information Networking
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• v.37 no.2
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• pp.85-93
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• 2010

WLAN virtualization can make multiple simultaneous experiments, each of which is conducted by a separate researcher, share scarce wireless resources in an IEEE 802.11 WLAN. The experiment performed in a virtualized WLAN should be consistent with that in a non-virtualized WLAN. The more similar these two experimental results, the better the consistency. To this end, we propose a novel virtualization scheme that has good consistency by preventing multiple simultaneous experiments from interacting with one another, without any modifications to the IEEE 802.11 standard. Through an intensive simulation study, we confirm that the consistency depends not only on the number of simultaneous experiments but also on wireless channel characteristics such as Doppler frequency and Ricean factor. According to such dependencies, the proposed scheme is optimized, so that it supports good consistency.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.10
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• pp.7-12
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• 2011

The effect of frequency interference situation between WiBro and WLAN in TV White Space band was taken into account in this paper. We assumed the using frequency in each system is applied in co-channel. When it comes to co-channel interference case, the minimum distance between WiBro ME and WLAN UE should be at least 210m if the maximum transmitter power of WiBro UE of 25dBm is limited. Analysis results of this paper can provide efficient reference and guideline to make spectrum plan for deploying WiBro and WLAN in TVWS.