Hong-Shik Park

Ant Colony Optimization Based Energy Saving Routing for Energy-Efficient Networks

This letter proposes an ant colony optimization (ACO) based energy saving routing, referred to as A-ESR, for energy efficient networks. The proposed A-ESR algorithm firstly re-formulates the energy-consumption minimized network (EMN) problem, which is NP-complete, into a simpler one by using the concept of traffic centrality. After that, it solves the re-formulated problem by 1) letting the flow to autonomously be aggregated on some specific heavy-loaded links and 2) switching off the other light-loaded links. Simulation results show that the A-ESR algorithm can get better performance than previous works in terms of energy efficiency.

Distributed antenna-based EPON-WiMAX integration and its cost-efficient cell planning

Achieving the benefits of high-capacity of optical networks and the mobility feature of wireless networks leads to integrate EPON and WiMAX for a promising broadband access solution. To efficiently put both benefits together, we propose an integration architecture of EPON-WiMAX based upon a Distributed Antenna (DA) environment, where collaborative Base Stations (BSs) concurrently transmit same wireless downlink signals (specifically for multicast and broadcast services (MBSs)) to Mobile Stations (MSs) in overlapped cell coverage areas. It helps enlarge the region of the available network coverage area by increasing Signal to Interference and Noise Ratio (SINR) in overlapped cell coverage areas through cooperation between Optical Line Terminal (OLT) and Optical Network Unit (ONU)- BS. We also present an cost-efficient cell planning to optimally control the size of overlapped cell coverage areas for the proposed DA-based integration architecture with a case study under a required region of the available network coverage area in consideration of the number of ONU-BSs and the distance between ONU-BSs. Performance evaluation results show that the proposed DA-based integration architecture enhances cost efficiency compared to the Traditional Antenna (TA) (non-DA)-based integration architecture with a similar level of spectral efficiency of MSs.

Energy-Aware Hybrid Data Aggregation Mechanism Considering the Energy Hole Problem in Asynchronous MAC-Based WSNs

The energy hole problem is caused by earlier turning off of sensor nodes nearer the sink due to more frequent data transmission, particularly in asynchronous MAC-based Wireless Sensor Networks (WSNs). To resolve this issue, this letter proposes an Energy-aware Hybrid Data Aggregation Mechanism (EHDAM) that is designed to adaptively control the number of data transmission with burst length based and time-out based transmissions. Especially, EHDAM adjusts the burst length threshold value in reciprocal proportion to the remaining energy state of the node so that reducing the number of data transmission; hence, EHDAM extends lifetimes of the nodes affected by the energy hole problem.

Ant Colony Optimization Based Self-Organizing QoS Framework in IP Networks

We propose an ant colony optimization based self-organizing QoS framework, referred to as AntQoS. AntQoS introduces a new concept named QoS colony which is a virtual sub colony to heuristically search a sub-optimal path for given QoS requirements in real-time. Compared with previous QoS frameworks, AntQoS provides two promising capabilities using QoS colonies: 1) self-organizing network QoS (not pre-defined class-based QoS), which autonomously reconfigures itself by promptly adapting to the changing network status, and 2) self-organizing controls, which autonomously resolve network congestion and resist network failures. Simulation results show that AntQoS guarantees diverse QoS requirements of emerging services while increasing network throughput.

A novel server selection method to achieve delay-based fairness in the server palm

It is pivotal to achieve delay-based fairness when users access the same content, especially in real-time services, from content-replicated servers based upon the client-server communication model. To resolve this issue, this letter proposes a novel server selection method of providing users with delay-based fairness from all the corresponding servers by applying the delay-based dynamic deficit round robin (D3RR) scheme. The deficit counter of the D3RR is adjusted based upon round trip times (RTTs) of data traffic measured by passive-based probing which ensures low resource waste. Performance evaluation results highlight that the delay variance among all the corresponding servers can be maintained as low as possible and delay-based fairness is guaranteed without unnecessary waste of resources.

Detection of Multicast Video Flooding Attack using the Pattern of Bandwidth Provisioning Efficiency

The rapid increase of distributed denial-of-service (DDoS) attacks, which deplete a link bandwidth and service resource by sending a tremendous flooding of traffic to a victim server, has threatened fundamental network service stability. First, this letter analyzes the unique properties of multicast video delivery, which is vulnerable to malicious video flooding attacks. Second, the effectiveness of the observation of bandwidth provisioning efficiency in the detection of anomalous patterns of multicast flooding is discussed and a traffic-sharing density-based flooding detection (TDFD) mechanism is proposed. Numerical analysis and simulation results are given to validate the performance of the TDFD.

Message-Embedded Random Access for Cellular M2M Communications

In this letter, we propose a message-embedded random access (MERA) scheme to simultaneously transmit both preambles (PAs) and messages (MSGs) as MSG-embedded PAs based on auto- and cross-correlation properties of Zadoff-Chu sequences using distinct root numbers. The proposed MERA scheme enables machine nodes to transmit small-sized data during a PA transmission on control channel (i.e., PRACH) without using any scheduling mechanism and resources on data channel (i.e., PUSCH). The performance of the proposed MERA scheme is mathematically analyzed and evaluated through simulations in terms of PA detection probability, MSG decoding probability, and the throughput of MSG transmissions on PRACH.

Traffic Load Distribution-Based Excess Bandwidth Allocation in Time-Division-Multiplexed PONs

Time-division-multiplexed passive optical networks (TDM-PONs) have been successful solutions for providing the huge bandwidth needed for quadruple-play services in last-mile networks. In this paper, the effects of excess bandwidth provisioning applied to a reservation-based TDM are analyzed in detail, and noble adaptive excess timeslot provisioning (ETP) mechanisms are proposed in the interoptical network unit (ONU) and intra-ONU domain in the TDM-PONs. Using traffic load distribution information observed in an optical line termination (OLT), a proposed deficit reservation-based dynamic bandwidth allocation, called dr-DBA, controls the amounts of excess timeslot bandwidths in order to efficiently serve the burst traffic of heavy-loaded ONUs while guaranteeing strict fair link-sharing. The authors also introduce a service work-based ETP bandwidth reservation as well as an optimal reservation class selection mechanism to support prioritized service in an intra-ONU so that serious node light-load penalty and bandwidth overbooking can be minimized. The performance results achieved by numerical analysis and simulations prove that proposed ETP mechanisms provide fair and optimal excess bandwidths to the ONUs according to the changes in traffic load distribution, while compensating the systematic weakness of each mechanism in both ONU domains.

Adaptive Packet Transmission Scheduling Using Multicast Service Efficiency in TDM-PON

In this paper, transmission scheduling issues related to multicast traffic, which focus on multicast service efficiency, are discussed for downstream packet transmission of a time-division-multiplexed passive optical network. First, the features of multicast traffic-sharing and the effects on multicast efficiency are analyzed in detail. Second, metrics, which are utilized in the measurement of multicast service efficiency, are introduced, and two kinds of fairness issues in multicast packet transmission are defined. Finally, an adaptive multicast packet transmission scheduling mechanism, called multicast-share weighted fair queuing, is proposed in order to stably guarantee fair amounts of effective throughputs to multicast sessions according to changes in the multicast service efficiencies of sessions. Analytic and simulation results confirm that the proposed mechanism guarantees the inter-session fairness in terms of effective throughput efficiently.

An Early Preamble Collision Detection Scheme Based on Tagged Preambles for Cellular M2M Random Access

In this paper, we propose an early preamble collision detection (e-PACD) scheme at the first step of random access (RA) procedure based on tagged preambles (PAs), which consist of both PA and tag Zadoff–Chu sequences using different root numbers, respectively. The proposed e-PACD scheme enables faster PA collision detection and notification, compared with the conventional RA scheme. Accordingly, it can reduce the RA delay and remove resource wastes which occur at the third step of the conventional RA procedure. The reduced RA delay achieved by the proposed e-PACD scheme can contribute to an ultralow latency requirement in fifth-generation (5G) cellular networks. In addition, the proposed e-PACD scheme enables the eNodeB to monitor the number of RA-attempting nodes (RA load) on each physical RA channel slot. The PACD probability and the RA load monitoring accuracy are mathematically analyzed, and the RA performance enhancement of the proposed scheme is evaluated in terms of RA success probability, average RA delay, and RA resource efficiency, compared with the conventional RA scheme.