• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.3
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• pp.755-761
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• 2013

Medium access control (MAC) protocols for wireless sensor networks make sensor nodes on state for energy-efficiency only when necessary. In this paper we present an energy efficient priority-based MAC protocol for energy-harvesting Wireless Sensor Networks (WSNs). For support priority-based packet transmission the proposed EEPB-MAC protocol uses the modified IEEE 802.15.4 beacon frames including priority bit, sender node address, and NAV value fields. A receiver node periodically wakes up, receives sender beacon frames, selects data sending sender, and broadcasts a beacon frame containing the selected sender's address. A receiver node selects sender node according to sender's data priority. A receiver nodes also adjust wake up period based on their energy states. Hence, the energy consumption of receiver node can be minimized. Through simulations and analytical analysis, we evaluate the performance of our proposed the EEPB-MAC protocol and compare it against the previous MACs. Results have shown that our protocol outperforms other MAC in terms of energy consumption, higher priority packet delivery delay.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4B
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• pp.391-398
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• 2011

In this paper, we propose a MAC protocol for visible light wireless LAN using LED light. The proposed MAC protocol has a function of automatic direction optimization for LED transceiver. There is periodical time slot for broadcasting and registration in the proposed MAC protocol. We used polling method for data transfer in the protocol since visible light is hard to detect carrier and collision by other mobile stations; thus we cannot use CSMA/CD method in visible light LAN. We also amended the MAC frame of IEEE 802.11 to propose a revised version for visible light wireless LAN using LED light. We investigate the performance of the proposed MAC protocol. When the bit rate of physical layer is 100 Mb/s, the net data throughput using the proposed MAC protocol is estimated to 94.386 Mb/s.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2638-2647
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• 2010

X-MAC reduces transmission delay and energy consumption by using a short preamble instead of the existing long preamble. To solve the problem of X-MAC, this paper proposes a new MAC protocol called Express-MAC. The wireless sensor network is mainly used for the purpose of gathering event data or situation information. Especially, the transmission pattern of the sensor network with the purpose of event detection such as intrusion detection is very intermittent as well as successively occurring when a single event takes place in most cases. By reflecting sensor network's key transmission patterns as above, EX-MAC has used multi-hub path's path reservation system and awake section's transmission time reservation method in data transmission when the first event takes place. The awake time reservation in transmission path has improved successive data transmission's end-to-end delay, and it has also increased efficiency in terms of energy consumption by reducing the preamble length of data transmission and reception node.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.9
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• pp.1883-1890
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• 2009

Existing MAC protocol can not show good performance in WMN environment. New MAC protocols is proposed because of Mobile Point's mobility, entire distributed environment, heavy traffic problems. This thesis proposes new channel contention method fur Mesh DCF. Mesh DCF uses ACH phase in TDMA frame to perform selection and elimination. Prioritized phases's count m and Fair Elimination phases's count n is determine contention level and make string probability to only one win the contention. Contention Number group's count K to determine the contention level in Fair Elimination Phase gives Fairness but make low probability to only one win the contention. It is sure that enough size of n and K can improve entire performance as result.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.1
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• pp.53-60
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• 2014

IEEE 802.15.4 is one of the most widely adopted physical layer standards in the area of LR-WPAN(Low-Rate Wireless Personal Area Network). Numerous previous researches have contributed to deep insights on energy efficiency, transmission throughput, and reliability that IEEE 802.15.4 delivers to the LR-WPAN. As a research that is orthogonal and complementary to previous researches, we explore the implementation and practical performance evaluation of IEEE 802.15.4 MAC software. We implement the MAC software from the perspective of the networking stack, exploring the issues raised when the MAC software serves as a functional component in a complete networking stack consisting of MAC, network as well as well as application support layers. The performance is evaluated on a realistic experimental software environment integrated with operating system, networking stack, and applications.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.7
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• pp.1547-1568
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• 2013

Wireless body area network (WBAN) is an emerging short-range wireless communication network with sensor nodes located on, in or around the human body for healthcare, entertainment and ubiquitous computing. In WBANs, energy is severely constrained which is the prime consideration in the medium access control (MAC) protocol design. In this paper, we propose a novel MAC protocol named Energy-efficient Relay MAC with dynamic Power Control (ERPC-MAC) to save energy consumption. Without relying on the additional devices, ERPC-MAC employs relaying nodes to provide relay service for nodes which consume energy fast. Accordingly the superframe adjustment is performed and then the network topology can be smoothly switched from single-hop to multi-hop. Moreover, for further energy saving and reliability improvement, the dynamic power control is introduced to adjust the power level whenever a node transmits its packets to the coordinator or the relaying node. To the best of the authors' knowledge, this is the first effort to integrate relay, topology adjustment and power control to improve the network performance in a WBAN. Comprehensive simulations are conducted to evaluate the performance. The results show that the ERPC-MAC is more superior to the existing standard and significantly prolongs the network lifetime.

• Journal of KIISE:Information Networking
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• v.37 no.3
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• pp.243-248
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• 2010

This thesis proposes a power saving MAC protocol for LTE base station which utilizes different graded DRX/DTX(Discontinuous. Reception/Transmission) that specified by 3GPP(Third Generation Partnership Project). Considering QoS in UE, proposed MAC protocol controls adaptive DRX/DTX cycle. When Packet delay of UE is less than normal time, LTE base station economize power by increasing DRX/DTX. When Packet delay of UE is more than normal time, delay of UE is decreased by guaranteed QoS. It depends on the traffic which is sent by UE. The proposed method is more improve power saving performance than another method which is unchanged DRX/DTX by conditions. Especially when set DRX/DTX up in conditions, it will meet the requirements of UE. In this thesis, I propose an power saving MAC protocol in an environment where LTE base station are communicated with UE and prove improvement in performance through simulations.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.6
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• pp.75-87
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• 2009

It is difficult to support QoS service in existing MAC Protocols in Wireless Mesh Network environments. while DCF can not support QoS, EDCA is operated with prioritized channel access method but can not give full performance. This thesis proposes frame management method to support QoS in Multi-Media DCF(MMDCF) MAC Protocol working in wireless mesh network. MMDCF uses ACH phase in TDMA frame to perform selection and elimination. Prioritized phases's count m and Fair Elimination phases's count n determine contention level and make string probability to only one win the contention. Forced TDMA Frame release method can support QoS requirements. MMDCF results good performance and good channel efficiency to support QoS requirements better than EDCA in multimedia stream environments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.4
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• pp.247-256
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• 2013

According to the complete standard document for PHY/MAC layer of visible light communication through the IEEE 802.15.7 WG on Sept. 2011, visible light communication lays a good foundation for developing a variety of application services. Thus, visible light communication moves to the advanced research period for developing application services, but most of applications are limited only to PtP service model. However, PtMP communication environment for VLC is required to accommodate more various applications. In this paper, we analyze an effect of key parameters on network performance in the star topology based visible personal area network system. We implement a simulator with considering attributes of PHY and MAC layer which are defined by IEEE 802.15.7 standard documents, and analyze the VLC performance.

• Journal of KIISE:Information Networking
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• v.37 no.5
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• pp.386-395
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• 2010

Widespread deployment of infrastructure WLANs has made Wi-Fi an integral part of today's Internet access technology. Despite its crucial role in affecting end-to-end performance, past research has focused on MAC protocol enhancement, analysis, and simulation-based performance evaluation without sufficiently considering a misbehavior stemming from capture effect. It is well known that the capture effect occurs frequently in wireless environment and incurs throughput unfairness between nodes. In this paper, we propose a novel Fair MAC algorithm which achieves fairness even under physically unfair environment. While satisfying the fairness, the proposed algorithm maximizes the system throughput. Extensive simulation results show that the proposed Fair MAC algorithm substantially improves fairness without throughput reduction.