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Z. Wu, S. Ganu and D. Raychaudhuri, "IRMA: Integrated Routing and MAC Scheduling in Multihop Wireless Mesh Networks," Proceedings of the Second IEEE Workshop on Wireless Mesh Networks (WiMesh 2006), Reston, VA, September 2006.

Zhao and D. Raychaudhuri, "On the Scalability of Hierarchical Hybrid Wireless Networks, Proceedings of the Conference on Information Sciences and Systems (CISS 2006), March 2006, pp. 711-716. [PDF]

S. Zhao, Z. Wu, A. Acharya and D. Raychaudhuri, "PARMA: A PHY?MAC Aware Routing Metric for Ad-Hoc Wireless Networks with Multi-Rate Radios," Proceedings of the IEEE International Symposium on a World of Wireless, Mobile and Multimeedia Networks (WoWMoM 2005), Taormina, Italy, June 2005, pp. 286-292. [PDF]

S, Gopal, S. Paul and D. Raychaudhuri, "Investigation of the TCP Simultaneous-Send Problem in 802.11 Wireless Local Area Networks," Proceedings of the International Conference on Communications (ICC 2005), May 2005, pp. 3594-3598. [PDF]

Z. Wu and D. Raychaudhuri, "D-LSMA: Distributed Link Scheduling Multiple Access Protocol for QoS in Ad-Hoc Networks." Proceedings of IEEE Global Telecommunications Conference (GLOBECOM 04), Dallas, TX, December 2004. pp. 1670-1675. [PDF]

L. Raju, S. Ganu, B. Anepu, I. Seskar and D. Raychaudhuri, "BEacon Assisted Discovery Protocol (BEAD) for Self-Organizing Hierarchical Wireless Ad-Hoc Networks," To appear in the Proceedings of IEEE Global Telecommunication Conference (GLOBECOM 2004), Dallas, TX, November 2004. [PDF]

S. Ganu, L. Raju, B. Anepu, I. Seskar and D. Raychaudhuri, "Architecture and Prototyping of an 802.11-based Self-Organizing Hierarchical Ad-Hoc Wireless Network (SOHAN)," Proceedings of the International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC 2004), Barcelona, Spain, September 2004.

S. Zhao, I. Seskar and D. Raychaudhuri, "Performance and Scalability of Self-Organizing Hierarchical Ad-Hoc Wireless Networks," Proceedings of the IEEE Wireless Communications and Networking Conference (WCNC'04), Atlanta, GA. March 2004, pp. 132-137. [PDF]

4G Mobile Network Architecture & Protocols

Project Objectives:

This project is aimed at design and prototyping of new network protocols and software for future next-generation wireless systems (“4G”), looking beyond the issues addressed by today’s mobile IP, WLAN and 3G solutions. Topics under consideration include: 3G/WLAN interworking, open-architecture wireless networks, data caching and content delivery for mobile users, protocols for self organization, routing in hierarchical ad-hoc networks and unlicensed band spectrum etiquette. In particular, we investigate an open-architecture, programmable mobile network approach that permits gradual evolution of service features via ad-hoc peer-level collaboration of wireless network entities, potentially reducing the need for complex standards that anticipate all future needs.

Technical Approach:

  • Uses the Open Access Research Testbed for Next-Generation Wireless Networks (ORBIT), which consists of open API wireless terminals, forwarding nodes, access points, switches and routers, to evaluate different approaches both in terms of protocol functionality and software performance.
  • Compatible upgrades to WLAN protocols for service features such as flow QoS and multicasting; interworking (global roaming, handoff, etc.) of multiple radio link technologies such as Bluetooth, 802.11, GPRS and 3G/WCDMA.
  • Self-organizing ad-hoc network protocols for discovery and routing, with particular focus on a hierarchical 802.11b architecture consisting of mobile nodes (MN), radio forwarding nodes (FN) and access points (AP).
  • Theoretical analysis of the capacity and scaling properties of the three-tier hierarchical hybrid wireless network, and system evaluation for an 802.11-based hierarchical network.
  • Cross-layer approaches to MAC, routing and transport in ad-hoc network scenarios.
  • Global Control Plane (GCP) approach to help disseminate control information among ad-hoc nodes and facilitate cross-layer algorithms such as the integrated routing/MAC scheduling algorithm and cross-layer transport protocol.
  • Content delivery techniques for mobile users, including those based on proactive Infostations caching and novel semantic routing techniques. [This project involves collaboration with Semandex Networks, Princeton, NJ]

Technical Rationale:
Mobile networks have traditionally been designed via extensions of existing fixed network protocols to support key mobility functions such as location management, authentication and handoff. Typically, these protocols were used in the context of homogeneous vertical architectures in which a single service such as GSM or 3G is provided to large numbers of mobile users. With the emergence of various new short-range and medium-range wireless data networks (such as Bluetooth and WLAN), there is a need for a more horizontal network architecture that accommodates heterogeneous radio links and permits evolution of mobile network services to include basic mobility features as well as newer requirements such as self-organization, ad-hoc routing, QoS, multicasting, content caching, etc. Such “4G” wireless networks can be realized with an IP-based core network for global routing along with more customized local-area radio access networks that support features such as dynamic handoff and ad-hoc routing.



This motivates research on open-architecture IP networks for wireless, as well as the specifics of new ad-hoc network protocols for self-organization, multi-hop routing, etc. Hierarchical structure is of beneficial to system scalability of ad-hoc networks. Cross-layer protocol design approaches are being considered as a means to achieve improved performance and robustness in future wireless networks. Global control plane applied to ad-hoc networks helps disseminate control information and works with cross-layer approaches to improve end-user performance.

Results to Date and Future Work Plan:
This project (which started in Fall 2001) has progressed from early design and testbed establishment to detailed design and evaluation of several candidate next-generation protocols for WLAN, 4G and sensor nets. The system performance of scaling properties of the hierarchical hybrid wireless network has been investigated extensively by both analytical and experimental approaches. The discovery protocol and the routing protocol have also been studied for the proposed three-tier hierarchical ad-hoc network. Furthermore, a proof-of-concept prototype has been developed for an 802.11-based self-organizing hierarchical ad-hoc wireless network (SOHAN). A distributed link scheduling multiple access (D-LSMA) protocol has been proposed for QoS support in multi-hop ad-hoc networks. Cross-layer design and global control plane approaches have been adopted in MAC, routing and transport. We have developed the PHY/MAC aware routing metric for ad-hoc wireless networks with multi-rate radios (PARMA), the integrated routing and MAC scheduling algorithm (IRMA), and the cross-layer aware transport protocol (CLAP). Moreover, the ORBIT testbed located at the WINLAB Tech Center facility includes open-source Linux routers, open API access points, radio forwarding nodes and sensor nodes that can be used for a variety of experimental purposes. A number of experimental studies have been conducted by the Mobinets group, including ad-hoc network routing, ad-hoc network topology discovery, integrated ad-hoc network MAC/routing protocols, scheduling in WLAN, enhanced MAC for ad-hoc networks, cross-layer transport protocols, and content multicasting. The ORBIT testbed project described in a separate focus project sheet is an outgrowth of this activity. In future work, we plan to provide holistic solutions for next-generation wireless systems, with focus on scaling, topology optimization, efficient multi-hop MAC, hierarchical structure, use of multiple frequencies, spectrum coordination procedures, and global control plane approach.

Ad-hoc Network Talk at PIMRC'04. more

Prof. D. Raychaudhuri

Ivan Seskar

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