Seung-Wha Yoo

LoWMob: Intra-PAN Mobility Support Schemes for 6LoWPAN

Mobility in 6LoWPAN (IPv6 over Low Power Personal Area Networks) is being utilized in realizing many applications where sensor nodes, while moving, sense and transmit the gathered data to a monitoring server. By employing IEEE802.15.4 as a baseline for the link layer technology, 6LoWPAN implies low data rate and low power consumption with periodic sleep and wakeups for sensor nodes, without requiring them to incorporate complex hardware. Also enabling sensor nodes with IPv6 ensures that the sensor data can be accessed anytime and anywhere from the world. Several existing mobility-related schemes like HMIPv6, MIPv6, HAWAII, and Cellular IP require active participation of mobile nodes in the mobility signaling, thus leading to the mobility-related changes in the protocol stack of mobile nodes. In this paper, we present LoWMob, which is a network-based mobility scheme for mobile 6LoWPAN nodes in which the mobility of 6LoWPAN nodes is handled at the network-side. LoWMob ensures multi-hop communication between gateways and mobile nodes with the help of the static nodes within a 6LoWPAN. In order to reduce the signaling overhead of static nodes for supporting mobile nodes, LoWMob proposes a mobility support packet format at the adaptation layer of 6LoWPAN. Also we present a distributed version of LoWMob, named as DLoWMob (or Distributed LoWMob), which employs Mobility Support Points (MSPs) to distribute the traffic concentration at the gateways and to optimize the multi-hop routing path between source and destination nodes in a 6LoWPAN. Moreover, we have also discussed the security considerations for our proposed mobility schemes. The performance of our proposed schemes is evaluated in terms of mobility signaling costs, end-to-end delay, and packet success ratio.

Route-over vs mesh-under routing in 6LoWPAN

Transmission of IPv6 packets over Low-power Wireless Personal Area Networks (6LoWPAN) was considered nearly impractical once. The size of IPv6 packets is much larger than the packet size of the IEEE 802.15.4 data link layer. 6LoWPAN implements an adaptation layer between network and data link layers. Main purpose of the adaptation layer is to fragment and reassemble IPv6 packets. Implementation of the adaptation layer enhances the routing/forwarding decision of packets both network and adaptation layers. We can divide the routing scheme in 6LoWPAN into two categories: the mesh-under and the route-over, based on the routing decision taken on adaptation layer or network layer respectively. In this paper we perform an analytical comparison between these two schemes in terms of the packet/fragment arrival probability, the total number of transmissions and the total delay between source and destination. We also compare the selective fragment retransmission mechanism between mesh-under and route-over schemes.

Allowable Propagation Delay for VoIP Calls of Acceptable Quality

In VoIP network the primary factors affecting the voice quality are codecs, delay and any associated echo, and packet loss. In this paper, E-model is used to evaluate voice quality for end-to-end voice services over IP-based network. Assuming an acceptable voice quality objective is given on R(?70) scale, the minimum amount of propagation delay available to the connection is called as allowable propagation delay. The allowable propagation delay is much more important factor than the one-way delay because the packetization and jitter buffer delay and transport delay are almost constant for the codec in VoIP networks. Thus, the allowable propagation delay budgets for each codec are provided in order to offer voice calls of acceptable quality in the IP telephony system.

Network Assisted Mobility Support for 6LoWPAN

This paper presents a network-assisted mobility support scheme for 6LoWPAN nodes, which enables multi-hop communication between the Gateway (GW) and the Mobile 6LoWPAN devices (MNs), with minimum mobility related signaling at the MNs end as compared to conventional mobility related protocols like MIPv6. The scheme provides mobility support to the MNs with the help of low cost static 6LoWPAN devices (SNs) which can be deployed in large numbers. In order to reduce the handover latency, the MN in the proposed scheme is assigned a fixed address which remains unchanged during its course of movement within the network. Moreover the scheme aims to reduce packets loss of the MN by predicting its future location and having a provision of buffering its packet at SNs when needed. The signaling overhead consumption needed to support a MN is determined through analytical modeling.

Inter-PAN Mobility Support for 6LoWPAN

This paper proposes Inter PAN mobility support for 6LoWPANs moving within an IP domain. In order to reduce the processing and signaling load on the mobile node (MN) caused by the movement, the mobility related processing of 6LoWPAN nodes is delegated to the existing PAN entities with less power constraints. Also this mobility support mechanism aims to reduce Inter-PAN Handover time by providing the information about the frequencies of surrounding PANs in the vicinity of the border nodes of the PAN. The signaling cost incurred is evaluated in terms of speed through analytical modeling and the performance is compared with HMIPv6. The results indicate a fair amount of reduction of signaling bandwidth achieved through the proposed support.

LNMP- Management architecture for IPv6 based low-power wireless Personal Area Networks (6LoWPAN)

Wireless sensor networks (WSNs) are becoming increasingly important because of their reduced cost and a range of real world military applications. IP connectivity to WSNs has enabled ubiquity of devices. 6LoWPAN networks are the realization of these IP based Ubiquitous Sensor Networks (IP-USNs). Management of such low power and constrained networks is a crucial problem. In this paper we propose LoWPAN Network Management Protocol (LNMP) which is the management architecture for 6LoWPAN based WSNs. We present operational and informational architectures for 6LoWPAN. Moreover, we also propose the design of the management information base for the management of such networks.

Energy-aware and bandwidth-efficient mobility architecture for 6LoWPAN

This paper proposes an energy aware and bandwidth efficient mobility support architecture which handles mobility of 6LoWPAN devices, such that the communication between it and its corresponding nodes remain undisrupted. As the 6LoWPAN devices are energy and resource constrained enabling mobility in these devices with the help of conventional host based protocols like MIPv6 is not suitable. Moreover, it may be possible in many scenarios that the mobile node (MN) moves far from the gateway (GW), while communicating with it. In this case the MN has to increase its transmission power, which may adversely affect its life time. In the proposed architecture static random deployed 6LoWPAN devices (SN) with same characteristics as the MNs, facilitate mobility such that the IP connectivity of the MN is maintained with minimum signaling at MNpsilas end. Thus this paper describes the link layer specific mechanisms needed between the SN and the MN to help it perform multi-hop communication with the GW. Moreover, it is designed keeping in mind the energy and resource constraint nature of SNs themselves. The signaling overhead for the SNs is determined through analytical modeling.

An empirical study to analyze the feasibility of WIFI for VANETs

Vehicular ad hoc networks (VANETs) are the relevant form of ubiquitous computing. Several protocols are being developed for V2R (vehicle to road side) and V2V (vehicle to vehicle) communication and the notion of intelligent vehicles is nurturing very rapidly. We have tested the existing WIFI protocol for V2V communication especially at high speed. We have proved, with the help of real life experiments and analytical justification, that WIFI is a successful means of communication between vehicles even at very high speed (i.e. 120 mph relative). Furthermore, several useful and novel applications (like parking, tourist information center, congestion control, advertisement campaign, shortest route, weather reporting, file sharing and on-board gaming) are suggested.

A simple lightweight authentic bootstrapping protocol for IPv6-based low rate wireless personal area networks (6LoWPANs)

Resource and power limited IPv6-based Low rate Wireless Personal Area Networks (6LoWPANs) requires energy efficient access control scheme for authentication, bootstrapping, and commissioning of prospective 6LoWPAN devices. In this paper, we propose an energy efficient lightweight mutual authentication scheme for 6LoWPANs which ensures secure network bootstrapping. The proposed scheme is independent of any key management infrastructure; keys or authentication secret data for mutual authentication is generated or transferred to 6LoWPAN device on-the-fly. Analysis of the proposed scheme have shown that the scheme is secure against various kinds of security and privacy attacks and is light-weight, adaptable, and scalable for 6LoWPANs.

GARPAN: gateway-assisted Inter-PAN routing for 6LoWPANs

IEEE802.15.4 devices are all geared up for deployment as sensor net-orks that are ubiquitous yet cost effective. An emphasis on keeping costs down results into sensor networks that do not warrant high connectivity, thereby making routing a more crucial activity. In the purview of routing, ZigBee consortium has developed a PAN routing protocol. Other notable efforts are underway chartered by IETF as 6LoWPAN working group. In this paper, we have revisited the routing approaches suggested both for intra-PAN and mesh. Our contribution here is first to identify the plausibility of using gateways in routing functionality in 6LoWPAN networks. Second, we propose a protocol that defines the role of gateways for enhancing the routability of 6LoWPANs. Through NS2-based simulation study, our performance analysis amenably supports the applicability of our protocol.