1 S. Ganu, L. Raju, B. Anepu, S. Zhao, I. Seskar and D. Raychaudhuri Rutgers, The State University of New Jersey Architecture and Prototyping of an 802.11- based Self-Organizing Hierarchical Ad-Hoc Wireless Network (SOHAN) PIMRC 2004, Barcelona Sept 5-8, 2004 •Research supported by NSF NRT Grant #ANI0335244 and by a grant from Cisco University Programs
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Architecture and Prototyping of an 802.11- based Self-Organizing
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S. Ganu, L. Raju, B. Anepu, S. Zhao, I. Seskar and D. Raychaudhuri
Rutgers, The State University of New Jersey
Architecture and Prototyping of an 802.11-based Self-Organizing Hierarchical Ad-Hoc Wireless Network (SOHAN)
PIMRC 2004, Barcelona
Sept 5-8, 2004
•Research supported by NSF NRT Grant #ANI0335244and by a grant from Cisco University Programs
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Introduction
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Introduction: Next Generation Wireless Network
Internet (IP-based)
Infostationcache
WLANAccess Point
WLANHot-Spot
VOIP(multi-mode)
Low-tier clusters(e.g. low power 802.11 sensor)
Ad-hocnetwork
extension
Public Switched Network(PSTN)
BTS
High-speed data & VOIP
Broadband Media cluster(e.g. UWB or MIMO)
BTS
BSC
MSC
CustomMobileInfrastructure(e.g. GSM, 3G)
CDMA, GSMor 3G radio access network
Generic mobile infrastructure
Today Future
GGSN,etc.
Voice(legacy)
High-speed data & VOIP
Relay node
Increasing role forad-hoc networks…
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Introduction: Flat vs. Hierarchical Ad-Hoc Nets� Hierarchical structure is essential, and helps to achieve:
� Scalability, i.e. improved max throughput and delay/QoS� Effective integration with 3G/4G, WLAN and Internet� Improved coverage & power consumption at subscriber radios
Wired Internet Infrastructure
Gateway node
Potential bottleneck
“Flat” mesh network with ad-hoc routing
End-user radios(with routing capability)
Wired Internet Infrastructure
BTS
BTS
AP
Forwarding node
End-user radios(no routing capability)
Multi-tieredInterfaces to
wired network
Wide Area Cell
3G cell
Hierarchical architecture with radio forwarding nodes and AP’s/BS’s
Ad-hoc associations
Ad-hoc associations
Microcell
Forwarding NodeExtended Coverage
Power & computinglimitations at low-tier nodes
Throughput per node scales ~ 1/sqrt(n)
Throughput per node can scale ~1 with right ratio of FN’s, AP’s
Reference: 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 2004), March 21-24, 2004, Atlanta
under consideration at WINLAB� Tier 1: low-tier mobile nodes, e.g. low-power PDA’s, sensors, etc. (MN)� Tier 2: forwarding nodes (FN) with multiple radio interfaces (UWB, WLAN,
cellular…)� Tier 3: wired base stations and access points (BS or AP)� Research on new protocols for: ad-hoc discovery, MAC and routing
InternetInternet
Forwarding node
low-tier (e.g. sensor) user nodes (MN)
Access Point
FN
AP
Wide-AreaCell
personal-area pico-cell
WLANmicro-cell
BTS
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Introduction: Application to WLAN Mesh� Hierarchical ad-hoc concept can be applied to extend coverage and QoS of
802.11 WLAN’s…� Useful for WLAN’s with coverage problems, home networks with QoS and/or coverage needs,
outdoor community networks, etc.� Some nodes (either network elements or terminals without power constraints) serve as FN’s� Requires extended discovery protocols (via beacons) and multi-hop routing� Optional upgrade of 802.11 MAC for efficient multihop operation
� Involves the configuration of the different devices in terms of channel assignments and initial transmit power level settings – for now, manual configurations using scripts
��������
��
����� ��
�������� Discovery Mechanism
� Filters links made available to the routing protocol based on desired objective function – reduces routing overhead
� Allows each node to apply a different objective depending on the role it plays
� Supports multi-channel operation of network
� Routing Mechanism� Uses the “logical” topology information presented by the discovery
mechanism in order to create and maintain local neighbor� Used to route data from the MN’s into the infrastructure network through
FN’s and AP’s
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SOHAN Protocols: Conceptual Overview
BTS A
AP1
FN1
FN2
FN3
FN4
AP2
AP3Wired Radio Access Network Infrastructure AP beacon(ID, frequency, power, ,bit-rate,service capabilities...)
FN beacon
BTS radiobeacon
BTS serviceadvertisement (into wired net)AP service
advertisement (into wired net)
End-user:seek (FN*, AP*)associate (FN1, AP2)routing update (FN1)routing update (AP2)send data