Over the past months, 3GPP was quite busy to ensure the NB-IoT made it into Release 13 before time ran out. So far, I’ve been looking into CRs and the Work Item description to get an idea of what is standardized because the Release 13 specification documents themselves did not yet contain NB-IoT content. Fortunately this has no changed in the latest edition of the documents and there and one company even pushed out a whitepaper to give an overview.
For those of you interested in the technical details of NB-IoT have a look at my previous posts on the topic and then head over to this interesting new whitepaper by Rohde and Schwarz, hot off the press! At the end they reference the specs that were extended for NB-IoT and I found the following two were particularly useful for my angle on the topic:
3GPP TS 36.331 is the LTE RRC Protocol Specification and the new chapter 6.7 now contains NB-IoT RRC messages, message definitions and NB SIB message descriptions.
3GPP TS 36.213 is about Physical Layer procedures and Chapter 16 focuses on NB-IoT procedures, for example downlink resources assignments in 16.4.1.3, which are done quite differently than in ‘classic’ broadband LTE. If you have a 20 MHz channel, many devices can be scheduled simultaneously and new assignments and grants can be handed out every millisecond. In NB-IoT things are very different. There’s only a 180 kHz channel so downlink transmissions are only scheduled for one device at a time. In addition an assignment can be made for several subframes and blind repetitions (in theory up to 2048) can be scheduled to improve indoor coverage.
Lots of other stuff to discover in the whitepaper and the specs, so bring some time and enjoy…