Challenges in (managing) Wireless Networks

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

Different scales of deployments 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

How are wireless networks different? “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

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

What tools do we need? 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.

Why is this hard? 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

Research (1) 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

Research (2) 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

What can be learned from licensed band networks? 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