• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.1529-1532
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• 2010

본 논문은 동종의 멀티코어에서 (m,k)-firm Deadline 을 가지는 태스크를 위한 실시간 시스템의 스케줄링 기법을 제안한다. 본 논문에서 제안된 알고리즘의 목적은 (m, k)-firm Deadline 을 만족시키는 확률을 증가시켜 최대의 Quality of Service 를 제공하는 것이다. 본 논문에서는 제안된 알고리즘이 QoS 를 보장함을 분석적으로 보이고 실험을 통해 알고리즘의 효율성을 검증한다.

• Journal of information and communication convergence engineering
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• v.10 no.2
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• pp.129-134
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• 2012

As application-specific requirements for wireless sensor networks emerge, both real-time and reliable communications become major research challenges in wireless sensor networks due to the many constraints on nodes and wireless links. To support these services, several protocols have been proposed. However, since most of them were designed as well as developed for general purpose applications, it is not recommended that they be directly adapted to applications with special requirements. In this paper, we propose a way to extend the current reliable transport protocol to cover a special real-time service, the (m,k)-firm deadline stream, in wireless sensor networks. While the proposed scheme is basically built on the PSFQ protocol for reliability, some features have been newly developed to support the (m,k)-firm stream efficiently. Finally, simulation results are given to demonstrate the feasibility of the proposed scheme in high traffic and with failed links.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.6
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• pp.237-244
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• 2013

We propose Energy-constrained Multiprocessor Real-Time Scheduling algorithms for (m,k)-firm deadline constrained tasks (EMRTS-MK). Rather than simply saving as much energy as possible, we consider energy as hard constraint under which the system remains functional and delivers an acceptable performance at least during the prescribed mission time. We evaluate EMRTS-MKs in several experiments, which quantitatively show that they achieve the scheduling objectives.

• ETRI Journal
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• v.32 no.3
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• pp.422-429
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• 2010

We present guaranteed dynamic priority assignment schemes for multiple real-time tasks subject to (m, k)-firm deadlines. The proposed schemes have two scheduling objectives: providing a bounded probability of missing (m, k)-firm constraints and maximizing the probability of deadline satisfactions. The second scheduling objective is especially necessary in order to provide the best quality of service as well as to satisfy the minimum requirements expressed by (m, k)-firm deadlines. We analytically establish that the proposed schemes provide a guarantee on the bounded probability of missing (m, k)-firm constraints. Experimental studies validate our analytical results and confirm the effectiveness and superiority of the proposed schemes with regard to their scheduling objectives.

• Journal of information and communication convergence engineering
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• v.10 no.3
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• pp.231-236
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• 2012

For real-time wireless sensor network applications, it is essential to provide different levels of quality of service (QoS) such as reliability, low latency, and fault-tolerant traffic control. To meet these requirements, an (m,k)-firm based real-time routing protocol has been proposed in our prior work, including a novel local transmission status indicator called local DBP (L_DBP). In this paper, a fault recovery scheme for (m,k)-firm real-time streams is proposed to improve the performance of our prior work, by contributing a delay-aware forwarding candidates selection algorithm for providing restricted redundancy of packets on multipath with bounded delay in case of transmission failure. Each node can utilize the evaluated stream DBP (G_DBP) and L_DBP values as well as the deadline information of packets to dynamically define the forwarding candidate set. Simulation results show that for real-time service, it is possible to achieve both reliability and timeliness in the fault recovery process, which consequently avoids dynamic failure and guarantees meeting the end-to-end QoS requirement.

• Journal of information and communication convergence engineering
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• v.14 no.2
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• pp.84-88
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• 2016

As good example of potential application-specific requirement, (m,k)-firm real-time streams have been recently introduced to deliver multimedia data efficiently in wireless sensor networks. In addition to stream model, communication protocols to meet specific (m,k)-firm real-time streams have been newly developed or extended from existing protocols. However, since the existing schemes for an (m,k)-firm stream have been proposed under typical flat architecture, the scalability problem remains unsolved when the number of real-time flows increases in the networks. To solve this problem, in this paper, we propose a new clustering scheme for an (m,k)-firm stream. The two different clustering algorithms are performed according to either the (m,k)-firm requirement or the deadline. Simulation results are presented to demonstrate the suitability of the proposed scheme under hierarchical architecture by showing that its performance is acceptable irrespective of the increase in the number of flows.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.475-477
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• 2010

In the power saving mechanism specified in IEEE 802.11, all node use the sam ATIM window size. Since the ATIM window size critically affects throughput and energy consumption, a fixed ATIM window does not perform well in all situations. This paper proposes the efficient power management mechanism considering network characteristic in 802.11. To reflect the network characteristic, the paper uses th (m,k)-firm deadline technique. Simulation result shows that proposed mechanism outperforms the IEEE 802.11 power saving mechanism in terms of the amount of power consumed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.9
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• pp.2050-2055
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• 2012

Since the wireless sensor networks become pervasive, various application-specific requirement have been emerged and suggested. Among them, reliability and real-time service are ones of big research challenges since sensed information is useless if a packet is lost and delivered later than deadline. Even though many research works have been proposed, they was designed to meet one of both requirements. To solve above problem, in this paper, we propose how to extend current protocol to meet two requirements together. More detailed, Mint Route protocol is revised to meet specific real-time requirement, (m,k)-firm stream in wireless sensor networks. Since the main operations in MintRoute are very similar to definition of (m,k)-firm stream, extension is achieved by modifying some parts of procedure. Finally, the simulation results are given and analyzed to validate the its suitability for reliable and real-time requirement.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.11
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• pp.2665-2670
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• 2015

VANET is ad-hoc network in which vehicles are treated as node and these nodes are communicating with each other as well as RSUs on the road. In VANET, scheduling is a very important issue as the request data are to be delivered to the recipient vehicle properly and accurately. It is also critical that any request data which is sent to the vehicle is received by it in the time period for which the vehicle will be in range of RSU. RSU picks the one with the highest priority to serve based on the scheduling scheme. In this paper, we propose a scheduling algorithm to select the one with the highest priority in RSU, in which an RSU can transfer the overload requests to other RSUs. We use the modified DBP scheme to calculate the priority of request data. Simulation results show that our scheme outperforms other scheduling schemes under various conditions.