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Purdue CWSA Workshop 2004

Grand Challenges in Wireless Grand Challenges in Wireless Wide Area Networks (WAN) Wide Area Networks (WAN) – A System Perspective– A System Perspective

Junyi LiJunyi LiSenior Director of TechnologySenior Director of TechnologyFlarion TechnologiesFlarion Technologies

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Purdue CWSA Workshop 2004

Evolution of Wireless WAN

circuit-switched airlinkcircuit-switched backboneno built-in data capability

2x circuit-switched airlink(RTT for voice, EV-DO for data)2x circuit-switched backbone(one for voice, one for data)

Single packet-switched airlinkover one packet-switched backbone

Converged IP Network

From narrowband circuits-switched to mobile broadband packet-switched

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Purdue CWSA Workshop 2004

Competition in Wireless WANCompetition in Wireless WAN

Evolution of traditional cellular towards 3G (UMTS, 1xEV DO/DV)

Evolution of WiFi towards WiMax: fixed 806.16a-d to mobile 806.16e

Emerging broadband mobile access (Flarion, Arraycom, Navini, etc)

In the near future, those systems may co-exist because of technology, political and economic reasons

Challenges: service and system/device integration– Seamless roaming– Overlapping service areas– Flexible programmable platform for development

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Purdue CWSA Workshop 2004

Challenges in Wireless WANChallenges in Wireless WAN

Users’ perspective– Full mobility– Always-on connectivity– Predictable QoS throughout serving area– High bursty data rate– Low latency for interactive real-time applications– Transparent support of existing applications: no change to applications,

devices, protocols, or content– Low battery consumption– High airlink security

Operators’ perspective– A rich set of IP QoS based services and applications– A large number of simultaneous users each of predictable QoS– IP based standard network architecture and mobility management– Native multicast for bandwidth efficiency and streaming applications– Toll quality voice and “instant on” voice– Significant profitability in a high usage flat fee environment

3G/UMTS fails on economics and performance WiFi falls short for ubiquity, mobility and competitiveness with DSL and

cable – How about WiMax?

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Purdue CWSA Workshop 2004

Driving ForcesDriving Forces

Applications– Web browsing may not be the dominate (killer) traffic

• Online gaming, streaming, PTT• “The most important future uses of wireless communications

are unknown”– How to make air interference sufficiently “flexible” to support

and mix all kinds of traffic requirement? Economics

– Pricing: how to induce higher network utilization and generate more revenue?

– QoS: why does it matter? how to link it with user experience (applications) and pricing?

Devices– How to increase battery life without sacrificing performance?– Always-on connectivity?– How to support a variety of high-end and low-end terminals?

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Purdue CWSA Workshop 2004

Open IssuesOpen Issues

Creative use of multiple antenna– Low cost and low complexity– Mobile environment– Limited feedback signaling– Seamless support of heterogeneous devices– How to fit multiple antenna techniques into overall system picture?

Uplink interference management– How to accommodate or exploit bursty interference caused by

bursty traffic?– How to jointly manage power control loop and traffic scheduling?

Scheduling– Downlink: well studied, but has room for improvement

• Spectral efficiency• QoS• Fairness

– Uplink: widely open• Should uplink be scheduled or not?• What is “uplink SNR”?• How to signal uplink QoS requirement?

– Combining MAC state management and traffic scheduling