• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.4
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• pp.612-623
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• 2022

Estimation of the presence of people in real time is extremely useful for businesses in providing better services. Many companies and researchers have attempted various researches in order to count the number of floating population in a specific space. Recently, as part of smart cities and digital twins, commercialization of measuring floating populations using Wi-Fi signals has become active in the public and private sectors. In this paper we present a method of estimating the floating population based on MAC-address values collected from smartphones. By distinguishing Real MAC-address and Random MAC-address values, we compare the estimated number of smartphone devices and the actual number of people caught on CCTV screens to evaluate the accuracy of the proposed method. And it appeared to have a similar correlation between the two datas. As a result, we present a method of estimating the floating population based on analyzing Wi-Fi Probe Requests.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.24-34
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• 2021

Estimation of the presence of people in real time is extremely useful for businesses in providing better services. Many companies and researchers have attempted various researches in order to count the number of floating population in specific space. Recently, as part of smart cities and digital twins, commercialization of measuring floating populations using Wi-Fi signals has become active in the public and private sectors. This paper explains the floating population measuring system from the perspective of general consumers(non-experts) who uses current population data. Specifically, it presents a method of estimating the floating population based on MAC-address values collected from smartphones. By distinguishing Real MAC-address and Random MAC-address values, we compare the estimated number of smartphone devices and the actual number of people caught on CCTV screens to evaluate the accuracy of the proposed method. And it appeared to have a similar correlation between the two datas. As a result, we present a method of estimating the floating population based on analyzing Wi-Fi Probe Requests

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.237-239
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• 2004

Wireless LAN Voice over IP(VoIP) equipment needs Quality-of-Service(QoS) with priority for processing real-time traffic. This paper shows transmit function implementation of wireless LAN(WLANs) media access control(MAC) support VoIP, and it has an advantage of guarantee of QoS and is adaptable to VoIP or mobile wireless equipment. The IEEE 802.11e standard in progress has four queues according to four access categories(AC) for transmit and the MAC transmits the data based on EDCA. The value of AC is from AC0 to AC3 and AC3 has the highest priority. The transmit method implemented at this paper ensure QoS using one transmit FIFO in hardware since real-time traffic data and non real-time traffic data has the different priority. The device driver classifies real-time data and non real-time data and transmit data to hardware with information about data type. The hardware conducts shorter backoff and selects faster AIFS slot for real-time data than it for non real-time data. Therefor It make give the real-time traffic data faster channel access chance than non real-time data and enhances QoS.

• Journal of the Institute of Convergence Signal Processing
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• v.12 no.2
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• pp.119-127
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• 2011

The paper surveys various analytical models for IEEE 802.11 medium access control protocols and critically discusses recent issues developing in wireless mobile ad hoc networks and their MACs. The surveyed MAC protocols include the standard IEEE 802.11 MAC suites such as IEEE 802.11 DCF, IEEE 802.11 PCF, IEEE 802.11e EDCA, and IEEE 802.11 ad hoc mode; and also the newer, de facto MAC protocols. We study the analytic models of the standard MAC suites followed by the newer analytic models that have been published in recent years. Also, the paper tries to include most of current literatures discussing analytic modeling of MAC in conjunction to some critical issues such as contention among ad hoc nodes, hidden terminal problems, and real-time service support.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.6
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• pp.88-96
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• 2011

Underwater acoustic communication is applicable in various areas, such as ocean data collection, undersea exploration and development, tactical surveillance, etc. Thus, robot control system construction used for underwater-robot like AUV or ROV is essential in these areas. In this paper, we propose the Message Merging MAC($M^2$-MAC) protocol, which is suitable for real time robot control system, considering energy efficiency in important parts of underwater acoustic sensor network constitution. In this proposed MAC protocol, gateway node receives the data from robot nodes according to the time slots that were allotted previously. And messages delivered from base-station are generated to one MAC frame by buffering process. Finally, generated MAC frames are broadcasted to all robot nodes in the cluster. Our suggested MAC protocol can also be hybrid MAC protocol, which is successful blend of contention based and contention-free based protocol through relevant procedure with Maintenance&Sleep (M&S) period, when new nodes join and leave as an orphan. We propose mathematical analysis model concerned about End-to-End delay and energy consumption, which is important factor in constructing real-time robot control system. We also verify the excellence of performance according to comparison of existing MAC protocols with our scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.1
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• pp.123-140
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• 2011

In this paper, we propose an Energy Efficient Media Access Control (EE-MAC) protocol for wireless sensor networks. The proposed scheme is designed to save power consumption and guarantee quality-of-service for real-time traffic. EE-MAC uses the superframe structure which is bounded by the transmission of a beacon frame and can have an active and an inactive portion. The active period is divided into the contention free period (CFP) for real-time traffic transmission and the contention access period (CAP) for non-real-time traffic transmission. We propose the exclusively allocated backoff scheme which assigns a unique backoff time value to each real-time node based on bandwidth allocation and admission control. This scheme can avoid collision between real-time nodes by controlling distributed fashion and take effect a statistical time division multiple access. We also propose the algorithm to change the duty cycle adaptively according to channel utilization of media depending on network traffic load. This algorithm can prolong network lifetime by reducing the amount of energy wasted on idle listening.

• Journal of Internet Computing and Services
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• v.9 no.4
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• pp.85-96
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• 2008

An authentication procedure on wired and wireless network will be done based on the registration and management process storing both the user's IP address and client device's MAC address information. However, existent MAC address registration/administration mechanisms were weak in MAC Spoofing attack as the attacker can change his/her own MAC address to client's MAC address. Therefore, an advanced mechanism should be proposed to protect the MAC address spoofing attack. But, existing techniques sequentially compare a sequence number on packet with previous one to distinguish the alteration and modification of MAC address. However, they are not sufficient to actively detect and protect the wireless MAC spoofing attack. In this paper, both AirSensor and AP are used in wireless network for collecting the MAC address on wireless packets. And then proposed module is used for detecting and protecting MAC spoofing attack in real time based on MAC Address Lookup table. The proposed mechanism provides enhanced detection/protection performance and it also provides a real time correspondence mechanism on wireless MAC spoofing attack with minimum delay.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.52.3-52
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• 2001

There are some problems to implement a realtime network system with Ethernet because the MAC(Medium Access Control) of Ethernet uses a CSMA/CD protocol, which introduces unexpected delays. In this paper, we designed a method to solve problems due to the Ethernet MAC. This method introduces a pseudo-MAC in application layer to support the real-time feature. So the presented method doesn´t need any modifications of protocols such as UDP/IP/MAC. The presented pseudo-MAC is based on both a token passing protocol and a publisher-subscriber protocol. The suggested realtime protocol is implemented and tested practically in a local area network. The proposed real-time network consists of a token controller node and general nodes.

• Journal of Sensor Science and Technology
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• v.22 no.1
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• pp.18-27
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• 2013

Real-time monitoring is one of the prime necessities in a weapon flight test that is required for the efficient and timely collection of large amounts of high-rate sampled data acquired by an event-trigger. The wireless sensor network is a good candidate to resolve this requirement, especially considering the inhospitable environment of a weapon flight test. In this paper, we propose a priority based multi-channel MAC protocol with CSMA/CA over a single radio for a real-time monitoring of a weapon flight test. Multi-channel transmissions of nodes can improve the network performance in wireless sensor networks. Our proposed MAC protocol has two operation modes: Normal mode and Priority Mode. In the normal mode, the node exploits the normal CSMA/CA mechanism. In the priority mode, the node has one of three grades - Class A, B, and C. The node uses a different CSMA/CA mechanism according to its grade that is determined by a signal level. High grade nodes can exploit more channels and lower backoff exponents than low ones, which allow high grade nodes to obtain more transmission opportunities. In addition, it can guarantee successful transmission of important data generated by high grade nodes. Simulation results show that the proposed MAC exhibits excellent performance in an event-triggered real-time application.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.5
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• pp.38-48
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• 2007

In ubiquitous environment, sensor networks that sense and transmit surrounding data without human intervention will become more important. If sensors are installed for detecting vehicles and measuring their speed in the road and that real-time information is given to drivers, it will be very effective for enhancing safety and controlling traffic in the road. In this paper, we proposed a new reliable and real-time sensor MAC protocol between AP and sensor nodes in order to provide real-time traffic flow information based on ubiquitous sensor networks. The proposed MAC allocates one TDMA slot for each sensor node on the IEEE 802.15.4 based channel structure, introduces relayed communication for distant sensors, and adopts a frame structure that supports retransmission for the case of errors. In addition, the proposed MAC synchronizes with AP by using beacon and adopts a hybrid tracking mode that supports economic power consumption according to various traffic situations, We implemented a simulator for the proposed MAC by using sim++ and evaluated various performances. The simulation results show that the proposed MAC reduces the power consumption and reveals excellent performance in real-time application systems.