Overview of Mobile Networking Initiatives at WINLAB

Overview of Mobile Networking Initiatives at WINLAB

Introduction: The Next Generation MSC Custom Mobile Infrastructure (e.g. GSM, 3G) BTS Public Switched Network (PSTN) BSC GGSN, etc. WLAN Access Point Internet (IP-based) Generic mobile infrastructure BTS Infostation cache High-speed data & VOIP WLAN Hot-Spot CDMA, GSM or 3G radio access network High-speed data & VOIP Voice (legacy) Ad-hoc network extension Relay node Broadband Media cluster (e.g. UWB or MIMO) VOIP (multi-mode) Today Future Low-tier clusters (e.g. low power 802.11 sensor)

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Research Overview Future Wireless Networks Research Topics Multimedia Networking <> <> <> Ad Hoc Networking <> <> <> <> Sensor Networking Security and Privacy Testbeds and Validation

Multimedia Networking

Wireless Multimedia Multicasting Challenges Limited Bandwidth Time-varying, error-prone channels Receiver heterogeneity Issue: What strategies can we employ to overcome the challenges of the wireless scenario? FEC ARQ Simulcast Tools Layers Proposed strategy being examined: 1. Employ multiple resolutions of video transmitted to different multicast groups 2. Clients subscribe to multicast groups based on their channel conditions 3. Centralized and distributed strategies for deciding appropriate group

Multiple Description Network Coding Network Coding: Incorporate coding at intermediate network nodes Achieves higher throughput in a multicast network Challenge: Transmission rate is limited by the minimum capacity of all receivers Multiple Description Network Coding: Multimedia MDC can ensure reliable media delivery MDs are transmitted at a rate of the maximum capacity of all receivers! Receivers with less capacity receive fewer descriptions Graceful reduction in media quality b1 b2 b1 b2 b1 b2 b1 b2 x*b1+y*b2

Ad Hoc Networking

Discovery and Routing in Ad Hoc Networks AP service advertisement (into wired net) AP1 BTS A Wired Radio Access Network Infrastructure AP2 BTS service advertisement (into wired net) BTS radio beacon Access Point: Seek (AP*, BTS*) Associate (AP2, BTS A) handoff update (AP2) handoff update (BTS A)..forward data & handoff AP3 AP beacon (ID, frequency, power,,bit-rate, service capabilities...) ad-hoc wireless network infrastructure FN beacon FN1 FN2 FN3 med-tier radio (e.g. 802.11x) FN4 Forwarding Node: seek (FN*, AP*) associate (FN3, AP3) routing update (FN3) routing update (AP3) forward data End-user: seek (FN*, AP*) associate (FN1, AP2) routing update (FN1) routing update (AP2) send data laptop may receive BTS beacon for wide-area service sensor node low-tier radio (e.g. 802.15.x) Protocols needed: Ad-hoc discovery (enhanced beacons, etc.) Ad-hoc MAC Ad-hoc network routing (extended metrics including energy) handoff, QoS control, multicast (..features)

Ad-Hoc MAC: D-LSMA Scheduling A B C RTS CTS DATA A E D Classified flows B C Scheduler Upper MAC D E to C RTS retransmit to C to E to C to E to C to E D-LSMA Lower MAC t 0 t 1 t 2 T Link scheduling to allow parallel transmissions, solves exposed node useful for QoS on ad-hoc FN-FN infrastructure in hierarchical systems Distributed scheduling algorithm (upper MAC), using 802.11-based lower MAC

Sensor Networking

Ad-Hoc Network: 3-Tier Sensor Net Self-organizing hierarchical ad-hoc wireless network (SOHAN) under consideration at WINLAB Tier 1: low-tier mobile nodes, e.g. low-power sensors (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 Internet Internet BTS WLAN micro-cell AP Forwarding node FN Access Point Wide-Area Cell low-tier (e.g. sensor) user nodes (MN) personal-area pico-cell

Sensor Energy Conservation via Adaptation Issue: Network Lifetime Question: How to determine the sleep interval? Tradeoff between energy conservation and responsiveness Active nodes: forwarding packets Backup nodes: Sleep + Wakeup Current solution: Use a fixed sleep interval that is small enough Energy conservation = sleep interval / wakeup time Proposed Solution: Adaptive sleep interval

Wireless Security and Privacy

Authentication in Hierarchical Ad Hoc Sensor Networks Public key certificates are not suitable for flat ad hoc networks To check certificate requires expensive public key operations Three tier architecture: Varying levels of computational power within the sensor network Sensors do not communicate with each other Forwarding nodes are radio-relay TESLA Certificates Alternative to PK certificates Uses symmetric key cryptography Delayed key disclosure AP FN SN Authentication framework: Access points provide filter to application TESLA certificates provide efficient sensor node handoff Weak and assured data authentication provided

3G Multicast Security Radio Network Subsystem (RNS) RNC UMTS Core Network SGSN Node B GGSN Node B BMSC Node B UMTS Terrestrial Radio Access Network Keys must be shared by multicast group participants As users join and leave, keys must be changed Internet 3GPP has proposed a new entity, the BMSC for managing broadcast and multicast services The BMSC can perform key management

Testbeds And Validation

Emergency Response Infostation Outdoor Infostations for Rapid Deployment For first responders to set up wireless communications infrastructure at disaster site Provides WLAN & sensor net services Infostations for caching large files (maps, etc.) Wireless backhaul link Prototype incorporates: 802.11 MAC+ for Infostations passthrough mode Content caching algorithm & software Solar panels, antennas and embedded processor with WLAN card Can be integrated with 802.11 ad-hoc sensors WINLAB s Emergency Infostation 2002

Medical Sensor with 802.11 WLAN First system-level MUSE prototype completed 11/03 New ECG interface board CerfCube platform with 802.11b (off-the shelf components) WINLAB drivers & networking software Next steps Make this prototype available to BioMed and UMDNJ collaborators Integrate with ZnO devices Continue work towards MUSE sensor SoP/SoC with low-power 802.11b

ORBIT Testbed Open-access next-generation wireless network testbed being developed for NSF network research testbeds (NRT) program Large scale radio grid emulator for evaluating new concepts for future wireless networks, e.g. ad-hoc sensor nets, pervasive systems... Also, outdoor field trial network covering RU Busch & NB campuses for real-world application work Research User of Testbed ns-2+ scripts & code downloads Global Internet Global Internet Static radio node Emulator Mapping Firewall High Speed Net Mobility Server Open API 3G BTS Dual-mode Radio device Radio link emulation Mobile node (robotic control) Wired routers Open API Access Point (802.11b) 3G access link Ad-hoc link End-user devices 1. Radio Grid for Lab Emulation 2. Field Trial Network

ORBIT Testbed: Radio Grid