Hong-Jong Jeong

EEDBR: Energy-Efficient Depth-Based Routing Protocol for Underwater Wireless Sensor Networks

Recently, Underwater Wireless Sensor Networks (UWSNs) have attracted much research attention from both academia and industry, in order to explore the vast underwater environment. However, designing network protocols is challenging in UWSNs since UWSNs have peculiar characteristics of large propagation delay, high error rate, low bandwidth and limited energy. In UWSNs, improving the energy efficiency is one of the most important issues since the replacement of the batteries of such nodes is very expensive due to harsh underwater environment. Hence, in this paper, we propose an energy efficient routing protocol, named EEDBR (Energy-Efficient Depth Based Routing protocol) for UWSNs. Our proposed protocol utilizes the depth of the sensor nodes for forwarding the data packets. Furthermore, the residual energy of the sensor nodes is also taken into account in order to improve the network life-time. Based on the comprehensive simulation using NS2, we observe that our proposed routing protocol contributes to the performance improvements in terms of the network lifetime, energy consumption and end-to-end delay.

Passive Duplicate Address-Detection Schemes for On-Demand Routing Protocols in Mobile Ad Hoc Networks

Internet protocol (IP) auto-configuration in mobile ad hoc networks (MANETs) has attracted much attention. Efficient duplicate address detection (DAD) schemes should be devised to provide each node with its unique address in the network. Generally, DAD schemes can be categorized into two classes: 1) active DAD and 2) passive DAD (PDAD). In this paper, we focus on PDAD schemes over on-demand ad hoc routing protocols. Specifically, we have three goals: 1) improving the accuracy of detecting address conflicts; 2) improving the successful detection success ratio; and 3) reducing the time taken to detect these conflicts. Unlike current approaches, we propose several schemes that exploit additional information, such as sequence number, location, and neighbor knowledge. Simulation results show that our approaches achieve better accuracy and shorter time to detect conflict addresses when compared with existing schemes.

An early retransmission technique to improve TCP performance for mobile ad hoc networks

As interests in MANET (mobile ad hoc networks) have increased, routing protocols suitable for MANET have been standardized specially in IETF (Internet Engineering Task Force). In addition to routing protocols, efforts to adopt the TCP stack as a reliable end-to-end transport protocol with some modifications appropriate for MANETs have been made for the smooth integration with the fixed Internet. Unlike previous approaches to improve TCP performance in MANETs, we modified the fast retransmission technique on the standard TCP. Basically, the fast retransmission technique utilizes the third duplicate ACK to trigger retransmission. However, if TCP is served by on-demand reactive ad-hoc routing protocols like DSR (dynamic source routing), AODV (ad hoc on-demand distance vector) and ABR (associativity-based routing) which can be considered as kinds of connection-oriented routing protocols until a route breakage occurs after a route acquisition, we can improve TCP performance by advancing the retransmission time using the first duplicate ACK triggered retransmission technique, without waiting for the third duplicate ACK packet. We show the performance improvement with this approach by using GIoMoSim simulator with AODV used as its underlying routing protocol, one of standardized on-demand reactive routing protocols in IETF.

Proxy protocol and PMIPv6 based mobility management for IEEE 802.11s wireless mesh networks

In Wireless Mesh Networks (WMNs), the mobility management for mesh clients is one of the most challenging issues since they need to be provided with continuous network access service, regardless of their movements. However, the IEEE 802.11s, standard protocol for layer-2 WMNs, overlooks mobility management, which can disturb the smooth operation of the network in a real environment. Therefore, in this paper, we propose a novel mobility management scheme that is compatible with the existing IEEE 802.11s standard. Our scheme performs intra-Mesh Basic Service Set (intra-MBSS) and inter-MBSS mobility management based on the proxy protocol in IEEE 802.11s and PMIPv6, without any modification of protocol messages and their usages. We implemented an IEEE 802.11s WMN test-bed and a mobility management protocol based on the open80211s implementation. We used this test-bed to verify that our proposed scheme achieves good performance in terms of TCP throughput and packet loss rate between mesh clients.

HIMALIS-C-ITS: Fast and secure mobility management scheme based on HIMALIS for cooperative ITS service in future networks

In order to realize the future networks, it is required to consider the characteristics of their services and applications as well as the research on the basic architecture. The Cooperative Intelligent Transportation System (C-ITS) service belongs to representative ones since it can prevent vehicular accidents, increase the efficiency of transportation system and reduce environmental pollution, while improving passengers convenience. The C-ITS services requires not only continuous network access but also the secure communication regardless of vehicles mobility since the services are tightly connected to the safety and life of passengers and pedestrians. In order to provide the continuous network access and secure communication to moving vehicles in the future networks based on the ID/locator split approach, authentication and location update of moving vehicles should be performed frequently, which result in significant signaling overheads. Therefore, in this paper, in order to integrate the C-ITS services with the ID/locator split approach based on HIMALIS architecture, we propose a novel mobility management scheme, named HIMALIS-C-ITS, which can contribute to reducing the delay in authentication and mitigating handover procedure at the mobile hosts as well as at the network entities in the edge network.

Trajectory Information-based Routing Protocol for Mobile Mesh Router in Wireless Mesh Networks

In this paper, we propose a routing protocol for WMNs to provide passengers in public transportation vehicles (e.g., bus and tram) with Internet access service. In order to support end users with a reliable Internet connection despite the mobility of vehicles, we assume that mesh router, called mobile mesh router (MMR), is installed in a vehicle and manages a route to Internet Gateway (IGW). We therefore propose an efficient routing protocol and its routing metric, called ETT-TR, considering trajectory information of vehicle as well as link quality in order to find a route between them. Using NS-2 simulations, we observe that our proposed routing protocol reduces the end-to-end delay and improves throughput performance.

Multipath Routing Based on Path Bandwidth in Multi-channel Wireless Mesh Networks

Mesh routers in wireless mesh networks (WMNs) utilize multiple radio interfaces in order to improve the performance of wireless network, resulting in transmitting multiple packets simultaneously on different orthogonal channels without interference. For the purpose of achieving the goal, routing protocols should be designed to improve the utilization of the network resources when selecting routes between source and destination nodes. However, single path routing protocols cannot explore the path providing sufficient bandwidth if the source traffic requires more bandwidth than the available bandwidth of the route. In this paper, we therefore propose a novel multipath routing algorithm which can explore multiple paths with sufficient bandwidth and transmit packets along disjointed paths simultaneously. we also introduce the path metrics which can estimate the available bandwidth of the path, considering the interface utilization information of each node, the channel diversity of route, and the intra-flow of the traffic. Using NS-2 simulations, we observe that our proposed multi-path routing protocol contributes to the performance improvements in terms of the end-to-end delay and the throughput in WMNs.

EK-DYMOv6: Implementation of DYMO with PacketBB Conformance in IPv6 Environment

In this paper we present our real-world DYMO implementation, called EK-DYMOv6. EK-DYMOv6 is the first DYMO implementation trial with two features: (a) conforming to recent DYMO (DYMO-05) and PacketBB (PacketBB-01) drafts, and (b) running on the Linux in IPv6 environment. EK-DYMOv6 was implemented with two parts: (a) a kernel module with Net- filter hooks and (b) a user-space routing daemon. We introduce the implementation detail, especially in a point of view of routing table location and PacketBB parser, and analyze the performance of our implementation through real test-bed experiments.

Improving the Accuracy of Passive Duplicate Address Detection Algorithms over MANET On-demand Routing Protocols

IP auto-configuration in mobile ad hoc networks has attracted much attention. Efficient DAD (duplicate address detection) techniques should be devised to provide each node with its unique address in the network. Generally, DAD schemes can be categorized into two classes: (a) active DAD and (b) passive DAD. In this paper, we focus on passive DAD schemes over on-demand ad-hoc routing protocols such as AODV and DYMO. In order to improve the accuracy of detecting address conflicts, we propose several schemes using additional information including sequence, location, or neighbor information

SMSR: A Scalable Multipath Source Routing Protocol for Wireless Sensor Networks

In wireless sensor networks (WSNs), providing resilience (fault tolerance) is a challenging issue. A lot of multipath routing protocols, therefore, have been proposed to achieve the goal; however, they usually suffer from control message overhead or a lack of scalability. Although some protocols utilize partially disjoint paths or longer alternate paths in order to reduce such overhead, they cannot guarantee resilience, because a single failure on a shared node breaks all the paths. In this paper, we therefore propose a scalable multipath source routing (SMSR) protocol. In SMSR, a sink node collects each sensor nodes one-hop upstream neighbor information during an initialization phase which the sink node then uses in order to construct several shortest node-disjoint downstream (sink-to-sensor) paths. When transmitting downstream packets, the source routing technique is exploited. On the other hand, each sensor node forwards upstream (sensor-to-sink) packets to one of its upstream neighbors, through the concept of gradient-based routing. The initialization phase depends on only one-time flooding and n (network size) times unicasting, and each sensor node manages only one-hop upstream neighbor information. In this sense, SMSR is scalable in terms of the overhead and the size of routing tables in sensor nodes. Particularly, since SMSR provides several node-disjoint paths with low overhead, it can guarantee resilience efficiently. Through experiments using both ns-2 simulation and our real world test-bed, we verify that SMSR achieves the goal better than other existing routing protocols.