1. PANEL DISCUSSION WoWMoM 2002 ARUP ACHARYA IBM T J WATSON RESEARCH CENTER arup@us.ibm.com

2. Conventional wisdom : Integration of WLAN and WWAN  Integrated WLAN and GPRS cards allow  High-speed access indoors (802.11a supports 54Mbps)  Wide-area connectivity via emerging wide-area data services (GPRS / 3G)  Ongoing research on seamless roaming between LAN/WAN In-building WLAN Wireless WAN (3G / GPRS)

3. 11 22 Multi-hop wireless LANs in metro areas  Emergence of high-speed 802.11a WLANs (108Mbps)  WLANs can operate a varying rates (1,2,..,11,..,22,..,54, 108)  Reception range decreases with rate  Given the above, we can think of a cellular-like architecture for multi-hop wireless networks  Start with a large cell; as nodes increase split into (higher rate) smaller cells  Connect to the Internet via multiple wireless LAN hops 54

4. Ongoing research on multi-hop WLAN  Enhanced medium access control (MAC) protocol for 802.11 that increases system throughput by supporting parallel transmissions (MACA-P)  New WLAN card architecture to support packet forwarding within the card  “wireless” router (see paper in WoWMoM 2002) A B P Q A B P Q Joint work with Archan Misra, IBM Research

5. MACA-P : basic idea  “Master” sender-receiver pair announces “schedule”  “Waiting room”, DATA tx period, ACK tx period  A neighboring node of master sender can transmit DATA in parallel  A neighbouring node of master receiver can receive in parallel A B P Q A B Q RTS P CTS DATA tx ACK control gap RTS CTS

6. Possible deployment scenarios  City-wide multi-hop fixed wireless LAN networks  could be run by a service operator, civic government  Two-tier mesh networks  First tier : access point for user  Second tier : access points interconnected via a wireless mesh  Backhaul to the Internet from a few points in the second tier mesh Eases deployment and cost

7. Application  VoIP gaining strength in the Internet  Enterprises switching to VoIP for new installations  Internet service providers offering VoIP  VoIP over DSL and Cable in trials  Can VoIP be extended over multi-hop metro wireless networks?  Initial source of revenue  Start offering media rich services gradually Location based Build a data network to support voice [wlan / IP based approach] Rather than extending a voice network to support data service