• Journal of KIISE:Information Networking
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• v.32 no.3
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• pp.391-403
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• 2005

Several nv6 mobility support protocols for mobile Internet services are proposed in IETP : Mobile Ipv6, Hierarchical Mobile Ipv6, and Fast Handovers over Mobile Ipv6. Recently, IEEE 802.11 network has also been widely deployed in public areas for mobile Internet services. In the near future, IPv6 mobility support over IEEE 802.11 network is expected to be a key function to actualize the All If-based mobile various services. For appropriate application of these protocols, the IPv6 mobility support protocols should be analyzed according to their characteristics in terms of signaling, handover latency, lost packets, and required buffer sire as well as the impact of lower layer such as IEEE 802.11 network. In this paper, we analyze the performance of the protocols over IEEE 802.11 network. We define a packet-level traffic model, a network system model, and a mobility model. From these models, we construct a framework for the performance analysis. We also make cost functions to formalize each protocol's performance. Lastly, we analyze the effect of varying parameters used to show diverse numerical results, and compare with each other. From the analysis results, it is concluded that each Protocol has contrary or contrastive advantages with other Protocols, so there is no protocol that holds a dominant position.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.1
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• pp.33-43
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• 2011

This paper proposes a traffic-aware TXOP adjustment algorithm for the IEEE 802.11e networks. In the proposed algorithm the access point (AP) monitors the network traffics periodically and adjusts the TXOP value of the non-QoS traffic in order to improve the network throughput while maintaining the QoS of video and voice applications. The experimental results show that the proposed algorithm outperforms the legacy IEEE 802.11e in terms of the throughput and the fairness.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2A
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• pp.128-139
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• 2004

As the Internet usage grows, people want to access the Internet while they are moving. To satisfy this requirement economically, IEEE 802.11 Wireless LANs(WLANs) are rapidly deployed. In order to support mobility, WLANs must provide smooth handoff mechanism. Recent studies show, however, handoff delay of WLANs exceeds 300ms, most of which is due to slow scanning mechanism finding a new AP. With this handoff delay, current WLANs is not suitable to provide seamless realtime interactive services such as VoIP sevice. In this paper, we analyze the current handoff method of IEEE 802.11 and we propose a new handoff algorithm which can decrease time needed for searching a new AP and thus reduce overall handoff time. We show by simulation that the proposed algorithm has shorter handoff delay than current handoff method.

• Journal of Digital Convergence
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• v.12 no.3
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• pp.249-254
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• 2014

Wireless LAN system is evolving toward high-speed data transmission and more accurate channel estimation is necessarily required to improve communication performance. The PLCP preamble field in IEEE 802.11 based wireless MODEM consists of ten short symbols and two long symbols and is used for synchronization and channel estimation. The existing least square (LS) channel estimation is based on only two long training symbols. After estimating channel response separately by using each long training symbol, the final channel estimation is obtained by the average of each estimation. In this paper, a new channel estimation algorithm is presented to improve the performance of the existing LS channel estimation algorithm. From the fact that the short training symbol consists of 12 non-zero subcarriers, it gives us a clue of being able to additionally estimate at least one fourth of channel coefficients. The new LS algorithm performs channel estimation based on both two long training symbols and a short training symbol. The proposed LS algorithm shows a little bit performance improvement over the existing LS estimation and it will be able to be applied to the IEEE 802.11p WAVE system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.10
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• pp.1950-1956
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• 2007

IEEE 802.16e has many points to be improved. Among them, fast handover is essential when user moves in high speed. In this paper we proposed a fast handover scheme using handover candidate BS set. This scheme is based on IEEE 802.16e, however according to the performance evaluation results through simulation; our proposed scheme shows more than 30% of handover delay reduction and at least 5% of handover drop probability improvement.

• Journal of Korea Society of Digital Industry and Information Management
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• v.16 no.2
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• pp.45-52
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• 2020

This paper is focused on the modulation scheme detection of the IEEE 802.11 standard. In the IEEE 802.11ac standard, the information of the modulation scheme is indicated by the modulation coding scheme (MCS) included in the VHT-SIG-A of the preamble field. Transmitting end determines the MCS index suitable for the low signal to noise ratio (SNR) situation and transmits the data accordingly. Since data field decoding can take place only when the receiving end acquires the MCS index information of the frame. Therefore, accurate MCS detection must be guaranteed before data field decoding. However, since the MCS index information is the information obtained through preamble field decoding, the detection rate can be affected significantly in a low SNR situation. In this paper, we propose a relatively robust modulation classification method based on deep learning to solve the low detection rate problem with a conventional method caused by a low SNR.

• The KIPS Transactions:PartC
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• v.17C no.6
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• pp.485-490
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• 2010

IEEE 802.11n supports two frame aggregation schemes, aggregation for MAC service data unit (A-MSDU) and aggregation for MAC protocol data unit (A-MPDU), to improve throughput at the MAC layer. In this paper, we propose a cooperative frame aggregation (CoFA), which can recover erroneous frames in a cooperative manner based on A-MPDU. Specifically, CoFA receive multiple frames from direct and relay paths, and combined multiple frames jointly. Numerical results show that CoFA outperforms direct transmission and relay transmission over diverse channel conditions.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1558-1562
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• 2005

This paper describes the design and implementation of a wireless home network system using Home Network Control Protocol (HNCP) called the wireless HNCP home network system. For wireless interfaces of HNCP, IEEE 802.11b and IEEE 802.15.4 standard protocols are considered. With the implementation of the wireless HNCP home network system, a simple analysis about coexistence between IEEE 802.11b and IEEE 802.15.4 is achieved. Through the implemented wireless HNCP home network system and the analytical results about the coexistence between both two different wireless protocols, the feasibility of the wireless HNCP home network system is shown.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.104-107
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• 2009

In this paper, we analyze the effect of interference between DTV system and IEEE 802.11n. We set DTV as a victim receiver and IEEE 802.11n as an interfering system. When they exist in the same area, they can make an interference effect. Therefore, we calculate a minimum coupling loss (MCL) and compare the resulting value with a path loss for determining whether there exists a potential interference or not. The minimum separation distance is determined when the path loss is larger than the MCL.

• The KIPS Transactions:PartC
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• v.16C no.3
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• pp.317-324
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• 2009

In this paper, a 4-way Handshake protocol in the IEEE 802.11i is analyzed in terms of both security and reliability. It is shown that the 4-way Handshake protocol breaks down under some conditions due to a MIC (message integrity code) failure, and a solution to fix it is proposed. It is also proposed that a new 2-way Handshake protocol which is more secure and efficient than the 4-way Handshake protocol.