Cat-0 was introduced in release 12 and was the first architecture outside of Cat-1 targeted to IoT needs. The design, like many other LTE specifications, is IP-based and runs in the licensed spectrum. A significant difference is in the uplink and downlink peak data rates (1 Mbps each), as opposed to Cat-1 at 10 Mbps for the downlink and 5 Mbps for the uplink. While the channel bandwidth stays at 20 MHz, the reduction in data rates greatly simplifies the design and reduces cost. Additionally, moving from a full duplex to a half-duplex architecture further improves cost and power.
Usually, the NAS layer of the LTE stack doesn't have much of a role in servicing UEs. In Cat-0, the 3GPP architects changed the NAS abilities to assist ...
