Ved P. Kafle

An ID/locator split architecture for future networks

The ID/locator split concept has recently been introduced in the standardization activities of ITU-T study group 13 for use in future networks. To contribute to ITU-Ts initiative, we first propose a naming system to configure host-names and identifiers and map them to locators. We then propose a network architecture that is based on the ID/locator split concept and the naming system. The proposed architecture allows the network layer to change protocols and locators without disturbing the upper-layer communication sessions. This capability is helpful for designing efficient solutions for mobility, multi-homing, routing, and security as well as for integrating heterogeneous network layer protocols.

Maximizing user satisfaction based on mobility in heterogeneous mobile multimedia communication networks

Future wireless/mobile system is expected to have heterogeneous wireless overlay networks for ubiquitous multimedia communication. In a such network environment, mobile users are likely to try to get attached to higher bandwidth network as bandwidth-hungry multimedia applications are increasing. However, the users have to perform vertical handoff to lower bandwidth network, as high bandwidth network become unavailable due to various reasons (such as its limited coverage, network congestion, etc.). In this paper, we discuss the problem of vertical handoff from a users perspective. For this purpose, we formulate user satisfaction as a function of bandwidth utility and handoff latency. Then, we investigate the effect of call holding time, user movement probability, etc. on the satisfaction that a user derives from the use of network service for multimedia applications. In addition, based on the evaluation, we present an algorithm for selecting a wireless network, which maximizes the effective user satisfaction.

MoRaRo: Mobile Router-Assisted Route Optimization for Network Mobility (NEMO) Support

The IETF (Internet Engineering Task Force) has developed a Network Mobility (NEMO) basic support protocol by extending the operation of Mobile IPv6 to provide uninterrupted Internet connectivity to the communicating nodes of mobile networks. The protocol uses a mobile router (MR) in the mobile network to perform prefix scope binding updates with its home agent (HA) to establish a bi-directional tunnel between the HA and MR. This solution reduces location-update signaling by making network movements transparent to the mobile nodes behind the MR. However, delays in data delivery and higher overheads are likely to occur because of sub-optimal routing and multiple encapsulation of data packets. To resolve these problems, we propose a mobile router-assisted route optimization (MoRaRo) scheme for NEMO support. With MoRaRo, a mobile node performs route optimization with a correspondent node only once, at the beginning of a session. After that the MR performs route optimization on behalf of all active mobile nodes when the network moves. The virtue of this scheme is that it requires only slight modification of the implementation of the NEMO basic support protocol at local entities such as the MR and mobile nodes of the mobile network, leaving entities in the core or in other administrative domains untouched. MoRaRo enables a correspondent node to forward packets directly to the mobile network without any tunneling, thus reducing packet delay and encapsulation overheads in the core network. To enable the scheme to be evaluated, we present the results of both theoretical analysis and simulation.

Extended Correspondent Registration Scheme for Reducing Handover Delay in Mobile IPv6

We present a new scheme for fast binding update with correspondent nodes to expedite the handover operation of mobile nodes in Mobile IPv6 protocol supporting networks. Our scheme is an extension of the Mobile IPv6 correspondent registration process that modifies some messages exchanged between a mobile node and a correspondent node. This scheme reduces the handover latency while providing the same level of security assurances for revealing the location information to the correspondent node as in the current Mobile IPv6 protocol. We also present an extension of the scheme to multihomed mobile nodes that have heterogeneous interfaces.

CoMoRoHo: Cooperative Mobile Router-Based Handover Scheme for Long-Vehicular Multihomed Networks

To support multimedia applications effectively in mobile networks, the handover latency or packet losses during handover should be very small. Addressing this issue, we present a cooperative mobile router-based handover (CoMoRoHo) scheme for long-vehicular multihomed mobile networks. The basic idea behind CoMoRoHo is to enable different mobile routers to access different subnets during a handover and cooperatively receive packets destined for each other. In general, packet losses are directly proportional to handover latency; however, the overlapped reception of packets from different subnets makes possible to minimize packet losses even without reducing handover latency. To evaluate the scheme, we carried out performance modeling of the CoMoRoHo scheme in comparison with the Fast Handover for Mobile IPv6 (FMIPv6) protocol in regard to the handover latency, packet loss, signaling overhead, and packet delivery overhead in access networks. The analysis results show that CoMoRoHo outperforms FMIPv6 by reducing the packet losses as well as signaling overheads by more than 50%. Moreover, CoMoRoHo imposes lower packet delivery overheads required for preventing packets from being dropped from access routers. We thus conclude that CoMoRoHo is a scalable scheme because its performance remains intact even when the access network is overloaded.

Dynamic mobile sensor network platform for ID-based communication

This paper presents the design of a dynamic mobile sensor network platform, consisting of mobile sensors, mobile sensor gateways, and sink servers. The sensor network platform supports heterogeneous protocols in the network layer and performs ID-based communication to deliver sensor data from the mobile sensors to the sinks, as well as to send control and monitoring commands from a sensor administrator to the mobile sensors. To reliably provide sensor data irrespective of their locations, the mobile sensors and mobile sensor gateways natively support mobility and multihoming and possess network access authentication and data transport security functions. The users can freely install new application programs over an already-deployed sensor network. They can configure the sensor network to operate in light-weight or full-function modes depending on the application requirements or available networking environments. Some components of the proposed sensor network platform are already in the standardization process in ITU and others can be brought for standardization in the near future.

Performance analysis of IP paging protocol in IEEE 802.11 networks

Recently, IEEE 802.11 wireless networks have been widely deployed in public areas for mobile Internet services. In the public wireless LAN systems, paging function is necessary to support various advanced services (e.g. voice over IP and message applications) and to provide efficient power management scheme. In next-generation mobile networks, the so-called all-IP networks, the paging function will be supported in the IP layer (i.e. IP paging). When IP paging protocol is deployed in IEEE 802.11 wireless networks, it may utilize the power saving mechanism supported in the IEEE 802.11 standard for more efficient power management. However, since the current power saving mechanism is based on a periodical wake-up mechanism with a fixed interval, it is difficult to optimize the power saving performance. In this paper, we analyze the performance of IP paging protocol over IEEE 802.11 power saving mode (PSM). We define a wake-up cost and a paging delay cost. Then, we study the effect of varying the length of the wake-up interval and the session arrival rate. In addition, we analyze the distribution of the session blocking probability due to the coarse-grained wake-up interval. Also, we investigate the optimal wake-up interval to minimize the total cost through simulations. These results indicate that it is necessary to find the optimal wake-up interval in order to minimize the total cost while satisfying the given paging delay constraints.

New mobility paradigm with ID/locator split in the future Internet

Introduction of ID/locator split into the future Internet architecture can make distributed and dynamic mobility management functions simpler and native. Unlike conventional IP mobility solutions, the new approach can offer smooth mobility across heterogeneous network-layer protocols (e.g. IPv4, IPv6) and other benefits. This paper first gives an overview of new features that ID/locator split-based architecture can bring about besides overcoming the limitations of conventional IP mobility protocols and then discusses the architecture, implementation, and performance of HIMALIS as an example of ID/locator split-based architecture. The performance results validate that HIMALIS has end-to-end throughputs and latencies similar to those of the conventional TCP/IP network. Moreover, the results verify that HIMALIS is capable to provide seamless handover across heterogeneous network-layer protocols.

A Scheme for Graceful Vertical Handover in Heterogeneous Overlay Networks

We present a graceful vertical handover scheme that provides graceful performance degradation during an upward vertical handover in heterogeneous overlay networks. This scheme harmonizes the functions performed by different layers, i.e., from the link layer to the application layer, and consequently smoothens the change in the throughput and reduces data losses in the network during a handover. By implementing the scheme in the ns-2 simulator, we present the results of the TCP performance with the graceful handover, which is significantly better than the performance without one

Performance evaluation of IP paging with power save mechanism

We evaluate the performance of IP paging with power save mechanism by formulating an analytical model and carrying out simulation study of integrated IP paging protocol (HPP) that integrates both the paging and power save functionality in IP layer. The results show that, compared to the mobile IP regional registration, the UPP significantly reduces the average power consumption of a mobile node and the signaling load in the access networks, while providing link layer independent mobility and power management functions.