Narrow Band IoT specifications was first introduced in 3GPP release 13 and then further enhanced in 3GPP release 14 with some essential features. Release 13 NB-IoT device category is referred as Cat NB1 or Cat N1 and Release 14 devices are referred as Cat NB2 or Cat N2.
| Parameter | Cat. NB1 | Cat. NB2 |
| 3GPP Release Specification | Release 13 | Release 14 |
| Operation Mode | FDD | FDD |
| No. of Rx Antenna | 1 | 1 |
| Tx Power Class | 20, 23 dBm | 14, 20, 23 dBm |
| Maximum Channel Bandwidth | 180 KHz | 180 KHz |
| Highest Modulation for UL and DL | QPSK | QPSK |
| Downlink Spatial Layers | 1 | 1 |
| Maximum DL Transport Block (TBS) | 680 bits | 2536 bits |
| No. of HARQ Processes | 1 | up to 2 |
| Peak DL Physical Layer Data Rate | 226.7 Kbps | 282 Kbps |
| DL channel coding type | Tai Bit Convolutional Coding (TBCC) | Tai Bit Convolutional Coding (TBCC) |
| Physical Layer Memory Requirement | 2112 soft channel bits | 7680 soft channel bits |
Additionally Cat NB2 devices has following features which are not available in Cat NB1
- Support of Positioning of Device using OTDOA
- Mobility enhancement from seamless cell re-selection
- Push to talk voice messaging
- New Device Power Class (14 dBm)
- Multicast transmission
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