The Wireless Future

Ed Knightly

ECE/CS Departments

Rice University

http://www.ece.rice.edu/~knightly

- Killer apps - The wireless device- The big challenges

Ed Knightly

The WiFi Laptop: A Killer App?(or 3G Laptop, or Metricom Laptop)

• Why do we (academics/researchers) love it?– Location freedom– Time efficiency

• However, we’re atypical

• What is it?– Portable office with high- speed Internet access

Ed Knightly

The WiFi Laptop: A Niche App

• Economics– Value added? Re-locate office. Not exciting to masses.– $30/month extra for same thing (except slower, less secure, …)

• Device– Most people don’t/won’t carry laptops everywhere (even at 2 lbs)

• Niche demand– Few have freedom of location to work– Few require constant high bandwidth connectivity to work

• Preliminary data– Tmobile – 10,000 WiFi subscribers – Metricom – 50,000 subscribers at peak– Total industry revenue 2002: $6M (source: Insight On Wireless)

Ed Knightly

Meta-Properties of Killer App’s

• Run on a PDA or cell phone – Pocket-sized devices only

• Enabled or enhanced by

PDA + wireless + mobility (vs. worse-than-wired)

Ed Knightly

Enabled & Potential Killer App’s (1/2)

• Exploit location specific information – Find the nearest {café, movie theater, …}– Wireless dating match-maker game– Spy game

Ed Knightly

Enabled & Potential Killer App’s (2/2)

• Immediacy/timeliness of information is critical

                                                             

                                               

Ed Knightly

Implication 1: Seamless Multi-tier

Seamless WiFi/3G integration is critical

• 3G cellular for coverage

• WiFi for efficient delivery of high aggregate bandwidth

3GWiFi

– PDA’s have modest bandwidth requirements due to form factor– High bandwidth requirements in aggregate– 0.4 vs. 38 Eurocents-per-Mb for WiFi vs. 3G (source Analysys)

Ed Knightly

Implication 2: Low Power Trumps High Bandwidth

• Power efficiency increasingly critical– Minimum power to achieve moderate throughput – Minimizing power/bit is well understood at PHY layer– Open problem: power aware MACs, OS, and applications

                      

Gb/sec

Ed Knightly

Implication 3: Radio Routers

• Real hot-spot cost is backhaul and management– $10k / hot spot + T1 for Mobilestar– Breakeven customers-per-AP too high

• Radio routers– Directed point-to-point radio links (vs. T1’s)– Challenge: scalable efficient infrastructure based on WiFi

Ed Knightly

Implication 4: Multi-Carrier Crunch

• Today: one carrier per hot spot (T-Mobile, Wayport, …)– Success will lure more carriers

• Problem: WiFi is worse than a zero-sum-game– Multiple APs will clobber each other

• Unlikely solution: Roaming (what is added value of 2nd carrier)

• Promising solution: Virtual Access Point– One physical infrastructure, virtualize MAC and services– Commercial solutions exist for wired routers– Open problem in wireless

Ed Knightly

Implication 5: A New IEEE 802.11

• Industry and Mobicom: MAC Balkanization– MAC for multi-rate– MAC for directional antennas– MAC for low power– MAC for QoS– MAC for fairness

• Challenge: All-in-one WiFi responsive to user needs– Ex. Directional antennas and QoS for low-power WiFi VoIP

Ed Knightly

And the Wireless Future Is…

• Device: Turbo-charged multi-tier wireless PDA– Always and instantly available– 44k/128k/WiFi automatic and transparent– WiFi is a hot-spot turbo boost for user, efficient

infrastructure for carrier

• Applications: Enabled apps vs. worse-than-wired– Unique to wireless/mobile/PDA/low-bandwidth scenario

• Implications: Technical challenges abound – Low power, WiFi+3G integration, innovative apps– MAC, Virtual AP, …