• Journal of Advanced Navigation Technology
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• v.22 no.4
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• pp.302-310
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• 2018

To realize the self-driving technology, there have been various system designs based on the related V2X standards, especially the IEEE 802.11p and WAVE standard supporting the WLAN V2X communication. On the other hand, the new standard IEEE 802.11ba defining supplementary wake-up radio operation is now under standardization targeting the low power operation, and it includes the V2P operation in use cases. However, if IEEE 802.11ba is used with the IEEE 802.11ba for V2X operation, the additional transmission procedure of wake-up frame in IEEE 802.11ba may cause the congestion problem and fails to meet the delay requirement. In this paper, the system structure of the combination of IEEE 802.11ba with the 802.11p is studied. In addition, based on the analysis and simulation, the considerations and improvements for effective low-power V2P communication in future self-driving technology using IEEE 802.11ba are proposed.

• Information and Communications Magazine
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• v.24 no.9
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• pp.49-59
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• 2007

본 논문에서는 IEEE 802.22 WRAN 표준화 중심으로 진행되고 있는 스펙트럼 센싱 기술에 관련된 내용들을 살펴보고 현재 IEEE 802.22 WG에 제안된 스펙트럼 센싱 기술들을 간략하게 소개하고 있다. 그리고 본논문에서는 IEEE802.22 표준화에 제안된 각사의 센싱기술들 중에서 최종적으로 표준안의 부록을 채택하는 방법으로 활용되었던 센싱기술 성능평가 방법인 다섯 가지 시뮬레이션 시나리오들에 대하여 설명하고 있다. 그런데 현재 IEEE 802.22 표준화에 제안된 센싱기술들은 Working Group에서 제시한 12개로 이루어진 DTV 신호 파일에 의해 센싱기술의 성능 검증을 위한 시뮬레이션을 수행하고 있다. 이의 DTV 신호들은 와싱톤 도심지 및 뉴욕에서 수집되었는데, 도심지, 교외, 주거지역 및 시골지역, 그리고 옥내외 채널환경 등 다양한 채널환경에서 수집된 신호들이다. 그리고 본 논문에서는 스펙트럼센싱 시스템의 구성을 제시하고 있고, 제시된 스펙트럼 센싱 구조에서 스펙트럼관리기능모듈, 스펙트럼센싱 기능 모듈, 그리고 채널집합분류기능 모듈에 대한 CPE와 기지국의 역할을 설명하고 있다. 또한 coarse 센싱 방법과 fine 센싱 방법의 결합으로 제시될 수 있는 hybrid 센싱 방법으로 incumbent 신호세기 및 센싱 단계에 따라 고속의 스펙트럼 센싱 타임(sensing time)을 도모할 수 있는 스펙트럼 센싱 과정을 제시하고 있다.

• 한국ITS학회:학술대회논문집
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• 2010.05a
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• pp.22-25
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• 2010

• Journal of Internet Computing and Services
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• v.9 no.4
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• pp.1-10
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• 2008

In this paper, a packet scheduling algorithm, called the modified PLFS, is proposed for real-time traffic in IEEE 802.22 WRAN systems. The modified PLFS(Packet Loss Fair Scheduling) algorithm utilizes not only the delay of the Head of Line(HOL) packets in buffer of each user but also the amount of expected loss packets in the next-next frame when a service will not be given in the next frame. The performances of the modified PLFS are compared with those of PLFS and M-LWDF in terms of the average packet loss rate and throughput. The simulation results show that the proposed scheduling algorithm performs much better than the PLFS and M-LWDF algorithms.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.2 s.58
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• pp.61-70
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• 2006

In this paper, we compare the performance of representative MIMO techniques such as space-time block code, closed-loop transmit diversity, and V-BLAST, etc., in IEEE 802.22 environments. We first develope deco-ding algorithms of the representative MIMO techniques and design a MIMO-OFDM system employing QPSK, 16 QAM, 64 QAM to cover several transmission rates. Since the frequency band used for IEEE 802.22 systems belongs mostly to V/UHF band and the angular spread of the received signal at the base station is very small, there Is a significant correlation between the signals from transmit antennas. Thus, in this paper, we compare the performance of MIMO-OFDM systems employing only two Tx antennas in correlated fading environments.

• Journal of Korea Society of Industrial Information Systems
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• v.22 no.3
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• pp.13-18
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• 2017

In this paper, We Numerically Analyze the Performance of the 802.11 Power Save Multi-Poll (PSMP) Operation. From the Analysis, we have Power Saving Efficiency Indicating how much time is Used for Power Consumption Over the Entire Operation Time. Consequently, we can Estimate the Operational Efficiency of the PSMP Operation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.9
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• pp.1243-1249
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• 2018

In this paper, we propose a scheme that tunes the backoff period for enhancing the system throughput with estimating the number of devices in IEEE 802.15.4 slotted carrier sense multiple access with collision avoidance (CSMA/CA) networks. Since each device does not sense the channel always in IEEE 802.15.4 slotted CSMA/CA networks, a personal area network (PAN) coordinator is used to estimate the number of active devices. The PAN coordinator broadcasts an optimal backoff period for the estimated number of devices through a beacon frame. In order to estimate the number of devices in run time, a simple moving average filter is utilized. We show the performance of our proposed scheme in terms of the estimated number of devices and the system throughput. The simulation results show that our proposed scheme can obtain higher system throughput than the IEEE 802.15.4 standard.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.7B
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• pp.538-549
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• 2008

Recently IEEE 802.22 WG has considered Cognitive Radio (CR) technology to overcome shortage of communication channels. For using CR technology, accurate and rapid sensing method selection is extremely important. According to the channel sensing method, it is of the utmost importance because it can affect the incumbent system protection. So, optimum selection of channel sensing method is very important. IEEE 802.22 gives the solution, name of fine sensing, but the solution can not adapt to various networks. So in this paper we propose Policy-based Channel Sensing Architecture and Algorithms for Cognitive Radio Networks. The proposed channel sensing architecture and algorithms can reduce both primary system detection time and quiet time in our simulation. Among the proposed sensing algorithm, channel division round robin sensing reduce average detection time up to 70% compare to fine sensing method in IEEE 802.22.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.2
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• pp.31-38
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• 2012

In this paper, a low area timing synchronization structure for the IEEE 802.11a OFDM MODEM SoC is proposed. The timing synchronization block of the IEEE 802.11a OFDM MODEM SoC requires large implementation area. In the proposed timing synchronization structure, it is shown that the number of multiplication can be reduced by using the transposed direct form filter. Furthermore, implementation area of the proposed structure can be more reduced using CSD(Canonic Signed Digit) and Common Sub-expression Sharing techniques. Through Verilog-HDL coding and synthesis, it is shown that the 22.7 % of implementation area can be reduced compared with the conventional one.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.12B
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• pp.1068-1075
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• 2006

Frequency resource value is growing bigger more with the development of the wireless communication. But Frequency shortage phenomenon is risen seriously because the need of Frequency resource is very many compared with the supply in an information society of the future. So we need Cognitive technique Radio which is taking the attention recently to use Frequency resource not to be not using efficiently. We propose efficient Dynamic Spectrum Allocation method in IEEE a 802.22 WRAN environment of CR foundation in this paper. To share spectrum more efficiently, we presented some Dynamic Spectrum Allocation technique to apply the Variable bandwidth, Mobility and verified this through the result of the simulations.