/ Academic Activities
am interested in the design and architecture of next generation IP-based
network architectures, applications and services including mobile / wireless
networks, especially SIP-based applications such as Voice-over-IP, Instant
Messaging & Presence. Following my PhD, I have more than
ten years of experience at industry research labs.
I am at IBM Research,
working on different aspects of SIP (Session Initiation Protocol)
and 802.11 based Wireless Mesh Networks. [more information].
I am also responsible for the Advanced
Networking Services micropractice for On-Demand Innovation Services
within IBM Research. The goal of ODIS is to tap IBM researchers for solving
hard customer problems.
to IBM Research, I was at NEC C&C
Research Labs, Princeton (May95 - Oct99). I designed the networking architecture
for a high speed mobile multimedia system including an IP switching scheme
("Ipsofacto") that was a precursor to MPLS. I led an offshore development
team of eight engineers for lab trials of this system with Telia
(Sweden) and Sprint. [more information]
have participated in leading technical conferences and panels on mobile
networking, including presenting tutorials to international audiences
on mobile networking. I have also been active within standards bodies
(IETF and ATM Forum) and have been awarded five patents on mobile and
high-speed networking, with seven others currently pending.
received my PhD in Computer Science, from Rutgers University, in 1995,
and currently also hold an Adjunct Faculty position at the Wireless Information
Networks Laboratory (WINLAB),
most recent information is available here.
: network infrastructure and applications
Scaling BladeCenters to handle high SIP loads
Designing SIP benchmarks for VoIP, Instant Messaging & Presence
Enabling applications to leverage SIP through a client-side API
and new infrastructure components
VoIP-enabled multi-player gaming
SIP-based handoff for dual-mode cell-phones
wireless networking protocols and architectures
(multi- protocol label switching)
Distribution Networks (CDNs)
infrastructures for web centers
protocols & architectures
Transport protocols : SCTP
Storage Area networking : ISCSI
(Jan 2000 -
Initiation Protocol (SIP) / Voice-over-IP (VoIP)
support for handling large SIP workloads : leading an effort to udesign
and develop a set of systems-level enhancements, both at the control layer
(SIP message processing) as well as media processing, for specific SIP
entities such as Session Border Controllers.
: characterize SIP workloads and develop benchmarks to capture mutliple
aspects of SIP usage such as Instant Messaging, VoIP and Presence.
applications : designed and implemented a client-side SIP service
that allows applications to exploit SIP. Developed new application of
SIP such as seamless transfer between multiple/ongoing conferences and
SIP-enabled multi-player networked games. Network infrastructure blocks
include coupling conference control server with a hardware media conferencing
unit, SIP-enabled web servers and game servers. Also worked on suporting
SIP based control for VoIP on wearable devices such as the Linux Watch.
control for dual-mode phones : Developed and prototyped a mechanism
for vertical handoff support for dual-mode phones using SIP
Force participation (a) Research representative to SIP Technology
Team study, Feb - April 2004, reporting findings to Senior VP (Technology)
(b) Task force on SIP and SIMPLE , sponsored by Corporate Strategy Office.
(Sept 2003) (c) Corporate Technology Team study on VoIP : Findings presented
to Senior VP (Technology), Sept 2002.
over 802.11: designed an architecture for providing quality-of-service
to SIP-based VoIP on 802.11 using the PCF feature of 802.11 medium access
Peer-to-peer VoIP and IM : Design/implementation of a SIP based
IM/VoIP for ad-hoc wireless network coupling application-layer control/data
messages with wireless mesh MAC protocols.
consulting : Participating in an consulting engagement for a large
Canadian bank on a strategy for incoprorating SIP. Previous engagements
include a e911-like service for in-building users in a campus environment
using wireless-LAN based location positioning techniques and VoIP.
project : This is a $5.4 million joint academia/industry project for
a next-generation wireless testbed. My contribution representing IBM Research
includes design/implemetation of a mesh networking architecture with a
Mesh Networks : Designed (a) a
"wireless router" with for packet forwarding between multiple wireless
interfaces combining MPLS labels with 802.11 MAC, and (b) a "multi-cellular"
architecture for simultaneous transmissions in neighboring cells of a
Architected a solution for an ODIS
engagement within a university for an in-building e911
solution by combining a 802.11 based position determination system with
based Hotspot : Developed an architecture/prototype for a Public Wireless
LAN system for pay-per-use Internet access at 802.11 hotspots, at multiple
tiers of service.
Based Web-switching : architected a solution for web-switching by
using a MPLS switch as a reverse proxy in front of a server farm avoiding
Content Distribution Networks (CDNs)
ways in which the intrinsic mobility support in IPv6 can be used for request
routing in CDNs .
Validation : designed a solution for checking if a IPSec tunnel between
two endhosts is working as advertised.
Virtualization : architected a solution for storage virtualization
by assiging virtual IP address and port numbers to disk blocks such that
movement of blocks is transparent to hosts.
Employment (May 95- Oct 99)
Staff Member, NEC C&C Research
Labs , Princeton, May 95 - Oct 99
Mobile ATM : Designed and implemented the mobile IP/ATM
protocol architecture for one of the first 25Mbps mobile broadband
networks based on wireless ATM. In addition, the core network was also
designed to support non-ATM wireless access such as wLAN and GSM.
I provided a core set of ATM Forum contributions on extending ATM
signaling/routing protocols for "mobile ATM" in the wireless ATM
working group, and supervised an 100 man-month offshore development team
for lab trials of this IP/ATM mobile broadband sytem with two large carriers,
Telia (Jan -Aug '99) and Sprint (May - July'99).
from NEC Corporation anouncing trials with Telia, Sweden.
- A presentation
describing the overall WATMnet system : my contributions
comprising the network
of WATMnet system at Wireless Broadband Testbeds (DEMO
'98) , Oct '98
of Mobile ATM prototype at ACM Mobicom'96
: Responsible for design/implementation of Ipsofacto, an IP switching
technology that was a precursor to MPLS whose key feature was support
for IP multicast. In conjunction with Mobile IP and RSVP,
Ipsofacto provided an IP based protocol architecture for the
WATMnet system. I supervised a eight-person offshore development
project (Feb - May'99) for deployment of Ipsofacto in the
Presentation and demonstration of MPLS multicast at MPLS'
- IP Switching over ATM project with GMD Fokus and trial
of Ipsofacto connecting NEC Princeton, NEC Berlin and Berkom.
- Ipsofacto was used by NEC Europe as a solution for IP/ATM integration,
in field trials for IthACI
, a EU project comprising NEC Europe, Alcatel and Cisco.
switch controller : An open architecture for IP/ATM switches and
base-stations, with separation of networking software(running on an external
Linux PC) from the switching hardware, using GSMP
(Generalised Switch Management Protocol) as the control interface, thus
enabling a choice of either IP or ATM protocol stacks to control a common
switching hardware. In 1996, this was one of the earliest
use of open-source software (Linux and Linux-ATM
stacks), for networking projects in industry.
: Wireless Information Networks Lab (WINLAB
) , Feb-May '95
Project : Combining Mobile IP and IP
: Rutgers University, CS
(Hons.) : IIT , Kharapgur, CS
& E, 1987
Thesis : Structuring
distributed algorithms and services in networks with mobile
Abstract ) (PS
IP, GPRS, 3GPP
SIP, SIMPLE, IM, VoIP, RTP
TCP/IP, IP Multicast (DVMRP, PIM), RSVP, Differentiated Services
MPLS (Multi-protocol Label Switching), IP Switching, GSMP
IP Routing : RIP,OSPF, BGP
Content Distribution Networks
ATM Signaling & Routing (UNI, PNNI,ILMI)
Wireless Medium Access Protocols (MAC), Bluetooth, 802.11
Web switching, Content distribution technologies, HTTP
IP Security Validator is an experimental tool that allows validation of
Virtual Private Network (VPN) configurations between two network interfaces.
As with testing connectivity using the Ping program, IP Security Validator
enables verification and validation of VPN configurations and their connectivity.
IFIP Technical Committee, Communication Systems (TC6), Working
Group 6.8 on Mobile and Wireless Communications.
2001 - Present
(Internet Engineering Task Force)
Overview of IP multicast in a Multi-Protocol Label Switching (MPLS)
August 2002, MPLS
Multicast Support in MPLS Networks. Internet Draft <draft-acharya-ipsofacto-mpls-mcast-00.txt>
Presented to the MPLS working group, 43rd IETF, March 99.
- IPSOFACTO : IP Switching Over Fast ATM Cell Transport.
Internet draft <draft-acharya-ipsw-fast-cell-00.txt>, July 1997
- Integrated location management for mobile ATM :interworking with
mobile telephony and mobile IP. WATM WG, ATM Forum, Sept 1997.
- Comparison of location management schemes for mobile ATM. WATM
WG, ATM Forum, Feb 1997.
- Primitives for location management and handoff in Mobile ATM
Networks. Wireless ATM Working Group, ATM Forum, Aug 1996.
control for point to multipoint connections in mobile ATM networks.
US Patent 6,643,279.
-System and method for transferring IP packets using fast ATM cell transport.
US patent 6,343,326. Jan 2002.
-Handoff method for an ATM wireless network wherein both the switch
and the mobile buffer cells and the mobile controls when the handoff
will occur. US patent 6,023,461. Feb 2000.
-Handoff-control technique for wireless ATM. US patent 5,974,036. Oct
-Method for Internet Protocol switching over fast ATM cell transport.
US patent 5,903,559. May 1999.
Patent applications filed
based VoIP MultiPlayer Network Games. Co-inventors. Filed : Feb 2004
- System and Apparatus for geographically distributed VoIP Conference
Service with enhanced QoS. Filed : Oct 2003
- Eanbling collaborative applications using SIP based VoIP. Filed :
system and service for achieving synchronous communication responsive
to dynamic status. Filed : Jan 2004
handling of SIP messages for VoIP call control. Filed : Nov 2003
- A method and apparatus for providing quality of service to VoIP over
802.11 wireless LANs. Filed : Nov 2003
- Network-layer enforcement
of differentiated connectivity for public wireless internet access.
Filed : Aug 2002
- A method and apparatus for content-aware for web-switching. Filed:
- Network l route control. Filed : Oct 2003
- Dynamis Service Discovery. Filed : Jan 2002
- Virtualization of ISCSI Storage. Filed : Jan 2002
- Validation of Network Communication Tunnels. Filed : May 2000
Professor, Wireless Information Networks Laboratory (WINLAB),
Global Internet and Next Generation Networks Symposium, Globecom
on Pervasive Wireless Networking (in conjunction with PerCom),
- The 25th IEEE International Conference on Distributed Computing Systems
- ACM Annual International Conference on Mobile Computing and Networking
(MobiCom) : 1999
, 2001 ,
2002 , 2004
- 1st IEEE International Conference on Mobile Ad-Hoc and Sensor
Systems (MASS), 2004
- IE EE International Workshop on IP Operations and Management (IPOM)
- 1st Working Conference on Wireless On-demand Network Systems (WONS)
- IFIP Personal Wireless Communications (PWC) : 2003,
- IEEE Global Communications Conference (Globecom) General Conference:
- First International Workshop on Broadband Wireless Multimedia:
Algorithms, Architectures and Applications (BroadWiM),
- The 5th ACM Intl Workshop on Wireless Mobile Multimedia (WoWMoM) :
- International Workshop
on Mobile Distributed Computing (MDC) : 2003,
- International Conference on E-business and Telecommunication Networks
- The 19th IEEE International Conference on Distributed Computing Systems
Session, ACM WoWMoM 2002
"Which wireless network technology will prevail for scalable mobile
multimedia services : cellular (3G/4G) vs. WLAN?" (Foils)
-Wireless ATM. Panel Session, Nomadic
- Invited Participant, Dagstuhl
Seminar "Mobile Multimedia Communication - Systems and Networks"
Schloss Dagstuhl International Conference and Research Center for Computer
Science. May4 - 6, 1999.
- Presentation at Wireless
Broadband Communications Workshop, Sept 1997, organised by European
Union ACTS Programme.
System Level Design Issues, IEEE Intl Conference on Pervasive Computing
and Communications (PerCom),
- Multicast Routing Session, IEEE Globecom 98
: NSF funded $5.45 million/ 4-year project on a Testbed for Next Generation
Wireless Networks and Applications. Participant in two experimental
work packages :
- Ad-hoc Networking in 802.11x WLAN scenarios
- Peer-to-peer infrastructure for VoIP and IM
Member , National Science Foundation (NSF) Wireless & Mobile
Communications & Networking Panel, 1997, Arlington.
Member, PhD Dissertation Committee of Sudeept Bhatnagar
Thesis title : " Distributed Admission Control in Core-Stateless Networks"
Computer Science Dept, Rutgers University, April 2004
External Member, PhD Dissertation Committee of Dragos Niculescu
Thesis title : "Forwarding and Positioning problems in Ad Hoc Networks"
Computer Science Dept, Rutgers University, March 2004.
: What is it, and how can we leverage it for next generation networking?
IBM Networking Services Global "Coffee Class". Dec, 2003.
- SIP : Tutorial, Impact and Opportunities. Pervasive Computing
Infrastructure Dept. Lunch-n-learn series talk. IBM TJ Watson Research
Center. Feb, 2004.
access protocols for wireless mesh networks supporting peer-to-peer
VoIP and IM. A. Acharya. Invited Presentation
at Rutgers WINLAB (Wireless Information Networks Laboratory), Fall 2003
Advisory Board meeting, Nov 2003. (Slides)
802.11 wireless networks. IBM TJ Watson - Seminars
in Communication. A. Acharya, Nov 2002.
Initiation Protocol (SIP) : A protocol for supporting multimedia in next-generation
2005. (With Archan Misra, IBM Research and Avshalom Houri, IBM)
Initiation Protocol (SIP): A Protocol for Managing Next Generation Networks.
13th IEEE Conference on Network Protocols (ICNP),
2005. (With Archan Misra, IBM Research and Avshalom Houri, IBM)
Initiation Protocol (SIP): Multimedia Signaling in Next Generation Networks.
1st Intl Conference on Communication System Software and Middleware (COMSWARE),
2006 (With A Houri, IBM)
ATM : Standards, architectures, protocols & implementation.
The 3rd Annual ACM/IEEE International Conference
on Mobile Computing and Networking ( Mobicom
'97 ), Sept 1997, Budapest.
Session Initiation Protocol to build Context-aware VoIP support for
Multiplayer Networked Games.
ACM Workshop on Network and Systems support for Games (NetGames)
2004. Also appears as IBM Research Report RC
and Implementation of SIP Network and Client Services for enabling Collaborative
Applications. 13th Intl Conference on Computer Communication
and Networks (ICCCN)
2004. Also appears as IBM Research Report RC
the power of Wearable Devices in a SIP infrastructure. Submitted
: A Label Switching MAC for Efficient Packet Forwarding in Multi Hop
Submitted for journal publication. Also appears as IBM Research Report
and Analysis of a Cooperative Medium Access scheme for High-Performance
Wireless Mesh Networks. 1st International conference on Broadband
Networks (BroadNets) 2004 -
Broadband Wireless Networking Symposium, Oct 2004.
Also appears as IBM Research Report RC
Performance Architectures for IP-based Multi-hop 802.11 networks.
IEEE Wireless Communications Magazine, Special Issue on "Merging
IP and Wireless Networks", Oct 2003.
Label-switching Packet Forwarding Architecture for Multi-hop Wireless
Paper Award at
IBM Research Report RC
: A MAC for Concurrent Transmissions in Multi-Hop Wireless Networks.
IEEE International Conference on Pervasive Computing and Communications
(Percom), March 2003. Also appears
as IBM Research Report RC
Concurrent Transmissions in Multi-hop Wireless Networks. Presentation
at 2nd NY
Metro Area Networking Workshop, Columbia University, Sept
2002 : Paper Slides
shorter version : MACA-P: A MAC Protocol to Improve Parallelism
in Multi-Hop Wireless Networks. IBM Research Report
in high performance data forwarding in multi-hop wireless networks.
IBM Research Report RC
802.11 wireless networks. Talk
presented at IBM Research Communications and Networking Reading
Group, Nov 2002
for public wLAN hotspots
: A Value-added System for Providing Tiered Wireless Services in Public
Hot-spots. IEEE 2003 International Conference on Communications
(ICC 2003). Also appears as
IBM Technical Report RC
: A framework for tiered services in public wireless LAN hot-spots.
To appear in IEEE Communications. A. Acharya, C. Bisdikian,
Young-Bae Ko and A. Misra. (Paper)
of IP multicast in a Multi-Protocol Label Switching Environment
(MPLS) Environment , IETF RFC
3353 , August 2002, MPLS
for IP multicast in MPLS, April 2002, IETF MPLS working
Switching using MPLS . Technical Focus, MPLSWorld
IP multicast support in MPLS. Lecture notes in Computer Science
1736. Also appears in 1st Intl wkshp on Networked Group Comunications,
: IP switching over fast ATM cell transport. Internet
, July '97
Mobility Support for Request-Routing in IPv6 CDNs.
IBM Technical Report . 7th Intl Workshop on web content caching
and distribution (WCW-7
IP and RSVP/QoS for mobile networks
: A reservation protocol for integrated services packet networks
with mobile hosts . ACM/Baltzer Journal of Wireless
Networks, Vol. 7, Issue 1, Jan 2001
services packet networks with mobile hosts : architecture and
performance . ACM/Baltzer Journal of Wireless Networks, Vol.
5, Issue 2, Mar 1999
adaptation schemes in networks with mobile hosts. The
fourth annual ACM/IEEE international conference
on Mobile computing and networking (Mobicom), Oct 1998.
accomodating mobile hosts in an integrated services packet network.
IEEE Infocom '97.
framework for delivering multicast messages in networks with mobile
hosts . ACM Mobile Networks and Applications,
Vol. 1, Issue 2, Oct 1996
multicast extensions for mobile internetworking. IEEE Infocom
- A Tool to Validate IPSEC Configurations. Usenix
LISA 2001 15th Systems Administration Conference, Dec '01
support for IP over wireless ATM. IEEE Communications, April
management in wireless ATM networks. IEEE Communications,
ATM : architecture, protocols and implementation.
2nd IEEE Intl workshop on broadband switching systems, Dec
to Peer (P2P) Networking
SRIRAM - A
Scalable, Resilient Autonomic Mesh.
IBM Systems Journal, Vol. 42, No. 1, 2003.
based request routing, 6th Intl Workshop on Caching
and Content Distribution (WCW-6
), June 2001
Web Switching , 1st New York Metro
Area Networking Wkshp, March 2001
and wide-area server selection : techniques
and challenges, Invited talk Opensig 2000
Admission Control for Heterogeneous Multicast with Bandwitdh Guarantees.
11th Intl Workshop on Quality of Service (IWQoS 2003),
June 2003. Also appears as Lecture Notes
in Computer Science 2707.
IP switching over fast ATM cell transport (IPSOFACTO) : Switching
multicast flows . IEEE Globecom '97
Switching over fast ATM cell transport. (IPSOFACTO) : IP multicast
over wireless ATM. IEEE ICUPC '98
multicast extensions for mobile internetworking. IEEE Infocom
framework for handling route changes and aggregation in IPSOFACTO.
IEEE Globecom '98
distributed algorithms for mobile computing networks. Computer
Communications 19 (1996)
distributed snapshots based on causal order of message delivery.
Information Processing Letters Vol. 44, No. 6, Dec '92
of occluded objects with heuristic search. Pattern Recognition
Vol. 23, No. 6, '90
search in restricted memory. Artificial
Intelligence Vol. 41, No. 2, Dec. '89