• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.1013-1016
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• 2012

IEEE 802.11 규격[1]은 2.4GHz 및 5GHz 대역에서 무선 근거리 접속 통신을 위한 국제 표준이다. 1997 년 2.4GHz 대역에서 1, 2 Mbps 의 속도를 지원하는 최초의 규격이 정의된 이래, 속도 개선을 위한 변복조 방식, 보안, QoS 등 다양한 요구 사항을 만족하기 위하여 표준이 지속적으로 개정되어 왔으며 2012 년 새로 개정된 표준이 발표된 바 있다. 특히, 최근 들어서 스마트폰의 무선랜 사용량이 폭발적으로 증가하고 무선랜 접속을 위한 핫스팟 역시 수가 크게 늘면서, 보안성을 유지하면서도 무선랜의 초기 연결접속 시간을 최소화(FILS; Fast Initial Link Setup)함으로써 무선랜 접속 요청 이용자 수에 확장성을 갖는 무선랜 규격을 제정할 필요성이 생기면서 IEEE 내에 802.11ai Task Group[3]이 승인되어 현재 표준화 작업을 진행중에 있다. IEEE 802.11 무선랜 규격에서 초기 연결접속 시간의 상당 부분을 네트워크 발견, 보안 접속, 인증 등에 소요하게 되어, IEEE 802.11ai에서는 보안성을 떨어뜨리지 않으면서도 빠르게 인증을 하기 위한 매커니즘에 대해 논의 중이다. 본 논문에서는 IEEE 802.11ai에서 논의 중인 "FILS를 위한 EAP/EAP-RP 기반의 빠른 인증" 기술에 대해 살펴보고, 이의 장단점을 분석하여 보다 개선된 형태의 빠른 인증 기법을 제안하고자 한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.4
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• pp.837-846
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• 2013

Recently, new technologies based on wireless LAN is being studied because utilization on smart phone using Wi-Fi is increased. 802.11 b/g/a is universalized wireless LAN technologies based on ISM, the standard developed in 11's working group of IEEE 802. standardization about IEEE 802.11ac that overcame limitation on Blue-ray of IEEE 802.11n or uncompressed video transmission and IEEE 802.af's technologies using TVWS is being actively studied. In this paper, ability of transmission considering the security on AP operated by these technologies have measured and done a comparative analysis with existing wireless LAN environment ability of transmission measured when appling security is more stable than existing ability of transmission in an environment with obstacles and shorten of transmission time is confirmed as a result of analysis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11B
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• pp.1178-1190
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• 2009

IEEE 802.11e proposed by IEEE 802.11 working group to guarantee QoS has contention based EDCA and contention free based HCCA. HCCA, a centralized polling based mechanism of 802.11e, needs a scheduling algorithm to allocate the network resource efficiently. The existing standard scheduler, however, is inefficient to support for QoS guarantee for real-time service having VBR traffic. To efficiently assign resource for VBR traffic, in this paper, we propose TXOP algorithm based on dual leaky bucket using average resource allocation and peak resource allocation. The minimum TXOP of each station is obtained by using statistical approach to maximize number of stations of which performance satisfy QoS target. Simulation results show that the proposed algorithm has much higher performance compared with reference scheduler in terms of throughput and delay.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.9
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• pp.100-106
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• 2013

AMI enables bi-directional exchange of information between utilities and consumers in order to maximize energy efficiency. To enable the AMI, it is essentially required to construct stable communication networks. This paper shows the AMI system based on IEEE 802.11s as one of the communication methods. Experimental results show that the wireless mesh network technology achieves a stable communication performance over a wide coverage.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6B
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• pp.420-429
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• 2008

Currently, IEEE 802.11 Network could not support optimized tunneling scheme and buffering scheme based on movement detection to reduce multimedia data packet loss when an MN move from current subnet to new subnet during handover. It is because IEEE 802.11 did not transfer information of movement detection to AP. In this paper, we proposed new fast handover scheme by using advanced access point and optimized snoop protocol for network based Proxy Mobile IPv6 in IEEE 802.11 Networks. During handover, the proposed scheme reduces both the multimedia data packet loss rate and the packet reordering problems without changing MN's mobility stack in IEEE 802.11 Networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.12B
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• pp.1996-2002
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• 2000

This paper investigates a priority scheme for IEEE 802.11 Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) protocol in order to provide short access times for priority frames (e.g. time-deadline traffic) even when the overall traffic on the wireless channel is heavy. Under the compatibility constraint for the IEEE 802.11 wireless LANs, two priority systems are simulated: no priority (current IEEE 802.11 standard) for time-deadline traffics and dynamic time-deadline priority. We evaluate algorithms to improve the time-deadline traffic performance using discrete event simulation (DES)

• The KIPS Transactions:PartC
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• v.13C no.4 s.107
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• pp.455-460
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• 2006

Currently, the IETF group is working on service differentiation in the Internet. However, in wireless environments such as Ad-hoc networks, where channel conditions are variable and bandwidth is scarce, the Internet differentiated services are suboptimal without lower layers' support. The IEEE 802.11 standard for Wireless LANs is the most widely used WLAN standard today. 1t has a mode of operation that can be used to provide service differentiation, but it has been shown to perform badly. In this paper, we present a new service differentiation scheme for support QoS in the wireless IEEE 802.11, which is based on a multiple queuing system to provide priority of user's flow. We simulate and analyze the performance of our algorithm and compare its performance with the original IEEE 802.11b protocol. Simulation results show that our approach increases overall throughput in the MAC layer.

• Journal of Korea Society of Industrial Information Systems
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• v.16 no.2
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• pp.1-11
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• 2011

A lot of works on the throughput analysis of the IEEE 802.11 DCF have been studied since last few years. However, we should predict the throughput of the IEEE 802.11g that we mostly use today because the existing numerical results do not consider exactly the IEEE 802.11g with the physical layer ERP-OFDM parameters. In particular, we might have different results in the working WLAN s compared with the simple predictions of the throughput using the previous results. In this paper, we directly monitor the ERP-OFDM physical layer parameters on the operating WLANs, and then analyze the saturated DCF throughput with the well-known analytic model. Moreover, we measure the bandwidth utilization on the real WLANs working with FTP services, and then compare them with the analytic results. According to the experiment results, we confirm the usefulness of the analytic models which assume the saturated traffic sources.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.3
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• pp.22-33
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• 2014

As a standard of WMNs, IEEE 802.11s supports two kinds of MAC algorithm: a mandatory EDCA used by IEEE 802.11e and an optional MCCA. While EDCA classifies traffic according to four Access Categories (AC) and offer differentiated service using a classified priority, MCCA can guarantee the specific bandwidth of users with a TDMA-style bandwidth reservation scheme between mesh routers. In case that a flow is VBR traffic of a multimedia application, MCCA has disadvantage that the reserved bandwidth does not be used entirely, though it guarantees required bandwidth of users and fairness using bandwidth reservation with neighbors' node. In this paper, we showed a problem that is wastes the reserved bandwidth when MCCA is enabled and proposed a new scheduling algorithm to prevent waste of bandwidth and to improve network utilization effectively, named Resource Sharing Round Robin (RSRR) scheduling. Finally we showed simulation results that performance of a proposed RSRR is better than the legacy MCCA through NS-2 simulation.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.4
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• pp.31-41
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• 2009

IEEE 802.11e proposed by IEEE 802.11 working group to guarantee QoS has contention based EDCA and contention free based HCCA. HCCA, a centralized polling based mechanism of 802.11e, needs a scheduling algorithm to allocate the network resource efficiently. The existing standard scheduler, however, is inefficient to support for QoS guarantee for real-time service having VBR traffic. To improve these limit, in this paper, we First, we propose priority polling algorithm which additionally considers the size of MSI and TXOP based on EDD algorithm to increase number of QSTAs. We also propose a dual token bucket TXOP allocation algorithm to reduce congestion caused by stations which enters network with considerable delay variance. TSPEC parameters, Maximum Burst Size (MBS) and Peak Data Rate (PR), are applied to design depth and token generation rate of two buckets. Simulation results show that the proposed algorithm has much higher performance compared with reference and SETT-EDD scheduler in terms of throughput and delay.