• Licensed vs. unlicensed spectrum
• UWB
• GPRS
• 802.11
• Bluetooth
• Asymmetric networks (data on TV channels, 3G for backchannel)

• Home
– No centralized controller
– Can’t ask users to do site surveys/planning
– Some co-operation with neighbors might be possible
• Enterprise
– Large number of access points
– Mobility
– Some central planning may be possible
• City-wide

• “Link” is not well-defined
– Which network to connect to?
– Network boundaries are not well defined
• Variable channel quality
• Broadcast nature
– Implications on density
– Interference from other (uncooperative) networks
– Makes performance/quality guarantees difficult
– Configuration may have to touch other entities

• Topology discovery is hard
– Hidden terminals, mobility
• Self-interference
– Multiple host interfaces
– Multi-hop networks

• Auto-configuration
– Site survey and planning should be unnecessary
• RF environment is changing all the time
• APs, clients should log information and respond to it
• Topology discovery
– Who’s affecting my transmissions
• Root cause analysis
– And some advice (e.g. your microwave is on)
• Standardization of metrics for reporting quantities like noise, power level etc.

• Many parameters to tune
– Frequency/channel/band, Power, Multiple radios, ….
• Needs cooperation between different entities
– Some of them (e.g. cordless phones) may not follow channel discipline
– Some devices such as microwave ovens are incapable of following
– Gaming/incentive issues

• Algorithms for determining frequency, power, and associations
– “Order out of chaos”
– Collaboration among competing entities
• RF-level innovations
– Channel bonding
– Spread spectrum, separate control channel
• Spectrum allocation and etiquettes
• Break up MAC into layers so that each layer can be innovated separately

• Leveraging multiple radios/devices
– To improve connectivity (seamless roaming)
– MIMO
• Security
– RF-level DoS attacks are easy to launch
– Detection of rogue access points and networks
– Privacy, man-in-the-middle attacks
• Better models for RF propagation, usage, mobility, antennas
– Tools to understand RF-level phenomenon and correlate them with MAC events

• Cell phone companies have very good radio planning tools (?)
– Are these tools useful for unlicensed band?
• Can these be automated?
• Co-operation in spectrum allocation improves performance