Arup Acharya

MRSVP: a resource reservation protocol for an integrated services network with mobile hosts

This paper describes a reservation protocol to provide real-time services to mobile users in an Integrated Services Packet Network. Mobility of hosts has significant impact on the quality of service provided to a real-time application. The currently proposed network system architecture and mechanisms to provide real-time services to fixed hosts are inadequate to accommodate the mobile hosts which can frequently change their point of attachments to the fixed network. Mobile hosts may experience wide variations of quality of service due to mobility. To reduce the impacts of mobility on QoS guarantees, a mobile host needs to make advance resource reservations at multiple locations it may possibly visit during the lifetime of the connection. The currently proposed reservation protocol in the Internet, RSVP, is not adequate to make such reservations for mobile hosts. In this paper, we describe a new reservation protocol, MRSVP, for supporting integrated services in a network with mobile hosts.

Mobility management in wireless ATM networks

Mobile ATM offers a common wired network infrastructure to support mobility of wireless terminals, independent of the wireless access protocol. In addition, it allows seamless migration to future wireless broadband services, such as wireless ATM, by enabling mobility of end-to-end ATM connections. In spite of the diversity in mobile networking technologies (e.g., cellular telephony, mobile-IP, packet data services, PCS), all of them require two fundamental mechanisms: location management and handoff. This article describes different schemes for augmenting a wired ATM network to support location management of mobile terminals and handoff protocols for rerouting a connection data path when the endpoint moves. A prototype implementation of mobile ATM integrating mobility support with ATM signaling and connection setup, is presented. It shows how mobile ATM may be used to provide mobility support to an IP terminal using non-ATM wireless access.

MACA-P: a MAC for concurrent transmissions in multi-hop wireless networks

This paper presents the initial design and performance study of MACA-P, a RTS/CTS based MAC protocol that enables simultaneous transmissions in multihop ad-hoc wireless networks. Providing such low-cost multihop and high performance wireless access networks is an important enabler of pervasive computing. MACA-P is a set of enhancements to the 802.11 DCF that allows parallel transmissions in many situations when two neighboring nodes are either both receivers or both transmitters, but a receiver and a transmitter are not neighbors. Like 802.11, MACA-P contains a contention-based reservation phase prior to data transmission. However, the data transmission is delayed by a control phase interval, which allows multiple sender-receiver pairs to synchronize their data transfers, thereby avoiding collisions and improving system throughput.

Structuring distributed algorithms for mobile hosts

Distributed algorithms have hitherto been designed for networks with static hosts. A mobile host (MH) can connect to the network from different locations at different times. This paper presents an operational system model for explicitly incorporating the effects of host mobility and proposes a general principle for structuring efficient distributed algorithms in this model. This principle is used to redesign two classical algorithms for distributed mutual exclusion for the mobile environment. We then consider a problem introduced solely by host mobility viz, location management for groups of MHs, and propose the concept of group location as an efficient approach to tackle the problem. Lastly, we present a framework which enables host mobility to be decoupled from the design of a distributed algorithm per se, to varying degrees.<<ETX>>

A framework for delivering multicast message in networks with mobile hosts

To accommodatemobile hosts (MHs) within existing data networks, the static network is augmented with “mobile support stations” (MSSs) that communicate directly with MHs, usually via wireless links. Connectivity of the overall network changes dynamically as MHs connect to the static network from different “locations” (MSSs) at different times. Compared to their desktop counterparts, mobile hosts face a new set of constraints namely, low bandwith of the wireless links, tight constraints on power consumption and a significantly lower computing capability. Thus, even without considering failures, integration of mobile computer within existing networks pose a new set of problems. In this paper, we look at the problems associated with delivering multicast meassages to mobile hosts. First, we identify how a mobile hosts ability to connect to different MSSs at different times, affects delivery of multicast messages and present schemes to deliver multicast messages to MHs fromatleast-one location, fromatmost-one location, and fromexactly-one location. Next, we introduce “multicast groups” of mobile hosts wherein each multicast group is associated with a “host view”, a set of MSSs representing theaggregate location information of the group. A host-view membership algorithm is then presented and combined with the multicast scheme for exactly-once delivery. As a result, to deliver a multicast message to a specified group, copies of the message need be propagated only to the MSSs in the groups host-view.

On accommodating mobile hosts in an integrated services packet network

This paper considers the support of real-time applications to mobile hosts in an integrated services packet network. We have proposed a service model for mobile hosts that can support adaptive applications which can withstand a wide range of available bandwidth, as well as applications which require mobility independent service guarantees. We describe an admission control scheme and a reservation protocol for implementing this service model. Our admission control scheme achieves high utilization of network resources.

Seamless SIP-based mobility for multimedia applications

Application-level protocol abstraction is required to support seamless mobility in next-generation heterogeneous wireless networks. Session initiation protocol (SIP) provides the required abstraction for mobility support for multimedia applications in such networks. However, the handoff procedure with SIP suffers from undesirable delay and hence packet loss in some cases, which is detrimental to applications like voice over IP (VoIP) or streaming video that demand stringent quality of service (QoS) requirements. In this article we present a SIP-based architecture that supports soft handoff for IP-centric wireless networks. Soft handoff ensures that there is no packet loss and that the end-to-end delay jitter is kept under control

Delivering multicast messages in networks with mobile hosts

There is a strong trend toward integrating portable computers within existing data networks. Traditional network protocols were designed assuming a static view of network connectivity. A mobile host can connect to the network from different locations at different times. This has led to the emergence of a new set of problems with regard to addressing schemes and network protocols for accommodating mobility within existing networks. The authors present a protocol for delivering a multicast message exactly once to a group of mobile destinations. The protocol is based on a system model derived from an architecture developed by J. Ioannidis et al. (1991), for mobile internetworking, relying on mobile support stations within the fixed network to communicate with mobile hosts.<<ETX>>

Rate adaptation schemes in networks with mobile hosts

Rate Adaptation Schemes in Networks with Mobtie Hosts bUP Kumar Tdtidar* B. R. Badrinath* Department of Computer Science Department of Computer Science Rutgers University Rutgers University New Buswi&, NJ 08903 New Brunswi&, NJ 08903 E-mti : tdAdar@cs.rutgers.edu E-mti : badri@cs.rutgers.edu

Integrated services packet networks with mobile hosts: architecture and performance

This paper considers the support of real-time services to mobile users in an Integrated Services Packet Network. In the currently existing architectures, the service guarantees provided to the mobile hosts are mobility dependent, i.e., mobile hosts experience wide variation in the quality of service and often service disruption when hosts move from one location to another. The network performance degrades significantly when mobile hosts are provided with mobility independent service guarantees. In this paper we have proposed a service model for mobile hosts that can support adaptive applications which can withstand service degradation and disruption, as well as applications which require mobility independent service guarantees. We describe an admission control scheme for implementing this service model and evaluate its performance by simulation experiments. Simulation results show that, if sufficient degree of multiplexing of the mobility dependent and independent services are allowed, the network does not suffer any significant performance degradation and in particular our admission control scheme achieves high utilization of network resources.