Radio Transmission Impairments

Communication based on Broadcasting

Wired communication is usually point-to-point.

Broadcast is hard to scale.

Wireless communication is inherently broadcast.

Does allow nodes to move.

Sensitivity to noise

Noise is naturally present in the environment from many sources.

Interference can be from other users or from malicious sources.

Impacts the throughput users can achieve.

How Do We Increase Network Capacity?

Easy to do in wired networks: simply add wires.

Fiber is especially attractive.

Adding wireless "links" increases interference.

Frequency reuse can help... subject to spatial limitations.

Or use different spaces ... subject to frequency limitations.

The capacity of the wireless network is fundamentally limited

Mobility Affects the Link Throughput

Quality of the transmission depends on distance and other factors.

Affects the throughput mobile users achieve.

Worst case is periods with no connectivity!

Mobility is an Issue even for Stationary Users

Mobile people and devices affect the transmission channel of stationary nodes.

And It Gets Worse …

The impact of mobility on transmission can be complex.

Mobility also affects addressing and routing.