Wireless link layers
Cellular Digital Packet Data (CDPD):
- Send IP packets over unoccupied radio channels within the analog cellular-telephone systems
- Not circuit switched => no per-call/call-duration charges
- Usage-based billing (contract w/ CDPD providers who have roaming agreements w/ other providers) => a wide area mobility solution (limited by availablility)
- Carrier provides IP address, but link layer protocols are responsible for ensuring packets are delivered
- Max data rate of 11 kbps