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Adaptive Duty Cycling MAC Protocols Using Closed-Loop Control for Wireless Sensor Networks
( Jaehyun Kim ),( Seoggyu Kim ),( Jaiyong Lee ) 한국인터넷정보학회 2011 KSII Transactions on Internet and Information Syst Vol.5 No.1
The fundamental design goal of wireless sensor MAC protocols is to minimize unnecessary power consumption of the sensor nodes, because of its stringent resource constraints and ultra-power limitation. In existing MAC protocols in wireless sensor networks (WSNs), duty cycling, in which each node periodically cycles between the active and sleep states, has been introduced to reduce unnecessary energy consumption. Existing MAC schemes, however, use a fixed duty cycling regardless of multi-hop communication and traffic fluctuations. On the other hand, there is a tradeoff between energy efficiency and delay caused by duty cycling mechanism in multi-hop communication and existing MAC approaches only tend to improve energy efficiency with sacrificing data delivery delay. In this paper, we propose two different MAC schemes (ADS-MAC and ELA-MAC) using closed-loop control in order to achieve both energy savings and minimal delay in wireless sensor networks. The two proposed MAC schemes, which are synchronous and asynchronous approaches, respectively, utilize an adaptive timer and a successive preload frame with closed-loop control for adaptive duty cycling. As a result, the analysis and the simulation results show that our schemes outperform existing schemes in terms of energy efficiency and delivery delay.
EPON에서의 높은 대역폭 사용효율과 QoS 지원을 위한 효율적인 스케줄링 알고리즘
김준석,연훈제,김석규,이재용,Kim Junseog,Yeon Hunje,Kim Seoggyu,Lee Jaiyong 한국통신학회 2006 韓國通信學會論文誌 Vol.31 No.2A
EPON은 널리 퍼져있는 이더넷(Ethernet) 기술을 사용하고, 낮은 이더넷 장비비용과 낮은 광(fiber) 기반비용을 제공하기 때문에, 광대역 고속 가입자 망에서 점점 더 매력적인 해법으로 관심을 끌고 있다. EPON에서는 서로 다른 ONU들이 데이터를 보내기 위해서 상향 채널을 공유해야 하기 때문에 상향 트래픽을 제어하는 것이 중요하다. 본 논문에서는 높은 대역폭 사용효율을 제공하며, 서비스 클래스 별로 서로 다른 QoS를 지원하는 스케줄링 알고리즘인 HUHG(High Utilization and Hybrid Granting) 알고리즘을 제안한다. 제안된 알고리즘은 고정된 EF(Expedited Forwarding) sub-cycle의 특성을 이용하여, 다음 cycle의 EF sub-cycle을 미리 할당하여 idle time을 제거 또는 줄임으로써 높은 대역폭 사용효율을 얻을 수 있을 뿐만 아니라, EF 클래스에 대한 패킷 delay와 delay variation을 최소화 할 수 있다. 본 논문에서는 제안된 알고리즘의 효과를 확인하기 위해서 기존 연구를 바탕으로 대역폭 사용효율을 분석하고, OPNET을 통한 모의실험 결과를 통해서 성능분석을 기술한다. In recent year, EPON(Ethernet PON) system is expected to be more attractive solutions for high speed, broadband access networks in next generation access networks due to the conversionce of low-cost ethernet equipment and low-cost fiber infrastructure. Upstream channel control algorithm is essential to hare upstream bandwidth in EPON. In this paper, we suggest HUHG(High Utilization and Hybrid Granting) algorithm for supporting high bandwidth utilization and QoS for different service class. This algorithm improves bandwidth utilization as removing or diminishing idle time of upstream channel using characteristics of fixed EF(Expedited Forwarding) sub-cycle. The proposed algorithm also minimizes the packet delay and delay variation of EF class. We conduct detailed simulation experiments using OPNET to study the performance and validate the effectiveness of the proposed algorithm.