IoT (Internet Of Things)

 

 

 

IoT Definition

 

IoT is a word that people used for years before it had a clear technical meaning. Let's pin it down from three sides. First, we look at a picture of the links that connect the things. Then we ask whether the technology was ready for those links. Finally, we sort out the overlapping names, such as M2M, MTC, D2D, LTN and LPWN.

What is IoT ?

For the past several month (as of Jan 2015), I have been hearing two words that everybody was talking about but nothing is clear about it in terms of technical details. One of them are 5G and the other is IoT (Internet of Things). I have been following up various news about 5G and had a dedicated section for 5G and now I am about to talk about IoT.

What is IoT ? It stands for Internet of Things. Basic idea is to connect EVERYTHING that you can think of by Internet. One small snapshot of connection would be as shown below.

 

IoT connection map with cellular, short range, backhaul and LPWAN links

 

I am using my own color coding to explain the situation in more detail.

  • Dotted Red :This is cellular link (meaning communication between cellular network and the device). By this link, I tried to indicate what 5G people call 'eMBB' (Enhanced Mobile Broadband) and URLLC(Ultra Reliable and Low Latency Communication). You may not call this type of communication as a typical IoT, but I think some use case of this type of communication can be categorized as IoT. That's why I put some example in this illustration. However this link requires extremly short latency (remote control over celluar network) or extremely high thoughput (downloading HD TV without compression). As of now (Oct 2015), this link would be difficult to be implemented. This link are one of the main target/motivation for 5G.
  • Dotted Green : By this link, I wanted to indicated a communication in which a lot of small end device(e.g, Water meter, power meter etc) directly communicates with a cellular network transmitting very low throughput data. This link will be the main target for LTE Cat 0,1,LTE-M,MTC or NB-IoT(NB-LTE).
  • Solid Red : This is also cellular link (meaning communication between cellular network and the device). But you might have already seen some of the application being used even now (Oct 2015) and the type of celluar technology is covering the whole range from 2G(GSM, CDMA),3G (WCDMA) through 4G (LTE). Relatively latest technology (as of Oct 2015) would be Category 3 LTE, but in most case this can be taken as too expensive solution. It start moving towards Category 1 and Category 0. I think you would see many Category 1 devices from next year (2016) and Category 0 devices from late next year (2016) or early 2017 in the market. Currently, Category 0 activity is being done at mobile baseband chipset level.
  • Solid Bule : This is a kind of short range communication being used between the device and a Gateway. Various communication technologies are used in this area. Probably ZigBee or similar technology has been used in most case, but recently there has been activities moving towards IEEE 802.15 based communication (e.g, 6 LoPAN). This type of communication would be more dominent in industrial IoT (e.g, Sensor network in a factory)
  • Solid Green : This represents a backhaul line connecting cellular tower or core network data pipe. If IoT is realized as everybody says/hopes, the amount of traffic flowing through this line would be enormous and this path should be wide enough to handle all those traffics. Though may not be visible to most of celluar people, this part is one of the most actively working area recently (as of late 2015).
  • Solid Violet : This represents Non-Celluar LPWAN like LoRa, SigFox etc.
  • Solid Orange : The orange lines connect the cloud to the two cellular sites and to the LPWAN gateway. They stand for the Internet and the servers behind the radio links. The data from every thing in the picture ends up on one of these lines, whichever radio link it used first.

 

You might have different interests in type of links depending on which industry you are working in. Personally I am more interested in solid red and dotted red line since I am in this area. It would be interesting to see which line gets thicker and which line gets thiner as time goes on.

Are We Ready ?

Connecting a few billion phones is a solved problem. Connecting many billions of small, cheap, battery powered things is a different problem, because every part of the cellular network was designed around the phone. So before anyone builds an IoT product, we should ask which technical pieces already exist and which ones are still missing.

Goal for IoT is clear. That's is.. 'Connect Everything by Internet'. The question is "Are we ready for this technicaly ?",

"Do we have all the technical compoents to achive the goal ?".

The answer is "NOT YET !" (But I will put down some of the recents observation below the following illustration)

Followings are some of the questions that pops up in my mind and I think we need to have clear answers at least to these questions before we start tyring to make any specific things.

But don't be disappointed too much. I think IoT is at least a little bit better than 5G in terms of technical details :).  We start having some industry standards for this and I think I can find some answers (partial answers) to thease questions. I will keep posting pages that would provide answers to these questions. Even though there is no perfect answers, it is always good practice for you to have your own questions before you study/develope anything in engineering.

 

Eight open technical questions about IoT

The questions in the picture were open in 2015. Several of them have answers now, because 3GPP added IoT features to LTE from Release 12 and Release 13 and carried them into 5G. The breakdown below takes each question in turn, in the words used in the picture.

  • How much Bandwidth required on Network side ? : Each device sends very little, but the number of devices is large. NB-IoT fits in 180 kHz, the width of one LTE resource block. So an operator can place it inside an LTE carrier, in its guard band, or on its own.
  • What kind of Radio Access technology to be used ? : There is no single answer. Cellular IoT, non-cellular LPWAN such as LoRa and SigFox, and short range radio such as ZigBee, Bluetooth and WiFi each found their own use cases. The What to Choose page lists the questions that decide between them.
  • Any industry specification ? : Yes. 3GPP specified LTE Cat 0 in Release 12, and LTE-M (Cat M1) and NB-IoT (Cat NB1) in Release 13. ETSI published the LTN group specifications in 2014. IEEE 802.15.4 is the radio under ZigBee, Thread and 6LoWPAN.
  • Go with existing Radio Technology or with completely new technology ? : Both happened. LTE-M is a revision of LTE, and it reuses most of the LTE procedures. NB-IoT keeps the LTE protocol stack, but its physical layer was redesigned for a 180 kHz carrier. LoRa and SigFox are new radio designs.
  • How to handle Authentication/Security for all those little tiny devices ? : Cellular IoT keeps the SIM based authentication of LTE. The SIM can also be soldered onto the board as an embedded SIM. In the LTN UNB design, each end point carries a 128 bit secret key that authenticates every radio packet.
  • Can current Network handle such a bursty transaction efficiently ? : 3GPP added features for this. PSM and eDRX let a device sleep for long periods. Control Plane CIoT EPS optimisation carries small data inside NAS signalling. So the network does not have to set up a data radio bearer for a few bytes.
  • Are we going with the same network technology for Low/Bursty data application and High/Bulky data application ? : No, and 5G made the split explicit. IMT-2020 defines three usage scenarios: eMBB for bulky data, URLLC for low latency, and mMTC for massive numbers of small devices. LTE-M and NB-IoT serve the mMTC role in 5G, and NR RedCap from Release 17 covers the middle ground.
  • Are these THINGs talking to each other only through Operator Network ? : Direct talking is allowed. LTE added D2D (ProSe) over the PC5 sidelink in Release 12, and 5G NR added its own sidelink in Release 16.
  • The questions were the right ones : almost every question in the picture later became a work item in 3GPP, ETSI or IEEE.
  • Cellular IoT was built by trimming LTE : narrower bandwidth, a single receive antenna and long sleep cycles are the main changes, and the protocol stack stayed.
  • The answers came slower than the questions : the When to come page follows how long the market took to use them.

Are you confused ?

Yes, I am confused. Each technology makes sense on its own. What confuses me is how the names overlap, because one name describes the application, another describes the radio, and a third describes the network.

For a while, I have been searching/watching/reading/devouring YouTube, web pages, WhitePapers and Specification documents about IoT. When you start reading about IoT, I am pretty sure that you will see some words about M2M and now start searching about M2M. And when you searching M2M and reading them, I am pretty sure that you will hear something about MTC, D2D. Then while I was googling about MTC, D2D and I started hearing about LTN and realized that even ETSI specification are released about LTN.

In addition to Cellular based IoT/M2M, many kinds of other network and short range wireless protocols that are designed for IoT/M2M or revised from existing application for IoT/M2M application, now we have even more confusing bubbles as illustrated below. If you are confused with this diagram, I would say my mission accomplished. This specific section is to confuse you :).  

Read through other sections and pages and get back to this sometimes. If this does not confuse you any further, your study on IoT is done :)

 

Ring of overlapping IoT terms surrounded by radio technology logos

 

I think I start understanding what each of these are talking about on its own, but I am still confused about how all of these interplay each other.

For now, in stead of trying too hard to get out of the unclear status I just decided to keep accumulating whatever I find. I am pretty sure that things would be clear by itself when I just have enough information/data compiled. This is how human brain works.

The picture above has two rings. The six orange ovals inside are names for the idea, and the logos outside are the actual radio technologies. Let's read the inner ring first, because that is where the names overlap.

  • IoT : Internet of Things. It is the goal of connecting things to the Internet, and it says nothing about the radio.
  • M2M : Machine to Machine. It is communication with no human at either end. ETSI and oneM2M use this term for the service layer above the network.
  • MTC : Machine Type Communication. It is the 3GPP name for M2M traffic on a cellular network, and LTE-M is short for LTE-MTC. See MTC.
  • D2D : Device to Device. Two devices talk directly, without passing through the base station. In 3GPP this is ProSe over the sidelink.
  • LTN : Low Throughput Network. It is the ETSI name for a wide area network built for a few bits per second. See LTN.
  • LPWN : Low Power Wireless Network in the picture, usually written LPWAN. It is the family of long range, low power radios such as LoRa and SigFox. See LPWAN.

The outer ring falls into three groups. ZigBee, Z-Wave, Thread, Bluetooth and WiFi are short range radios. LoRa, SigFox, NWave, Neul and Weightless, the W logo at the lower right, are LPWAN radios. The LTE/5G oval holds the cellular options: Cat 0, Cat 1, LTE-M and NB-IoT.

  • IoT, M2M and MTC answer different questions : IoT names the goal, M2M names the kind of traffic, and MTC names that traffic on a 3GPP network.
  • LTN is the ETSI name for what the industry calls LPWAN : both describe long range radios that carry a few bytes per message on a small battery.
  • The outer ring is where the real choice is made : a product picks one of those radios, and the What to Choose page lists the questions behind that choice.

Reference

[1]  M2M Summit 2014 | Joachim Dressler: Is LTE changing the M2M world?

[2]  Machine-to-Machine (M2M) Tutorial Trailer for IEEE ComSoc Tutorial Now

[3]  What is M2M?

[4]  NB-IOT - Enabling New Business Opportunities (HUAWEI)

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