IoT- A Pivot for Technology Convergence

Context

The intention of this article was to bring a snapshot of IoT (Internet of Things) as it is a rapidly growing technology and is highly relevant with the pandemic situation, accelerating its adoption like never before. While IoT as a concept started 2 decades ago, its growth was rapid during the last decade with projections of around 25 billion devices by 2021.

Interestingly, it is poised to be the technology convergence for many disciplines of engineering to include the likes of Transducer innovations, Metallurgical advances, Biological Research, next generation IP networks, Cloud Computing , Data Sciences, AI/ML, and Mechanical actuators, to mention a few. This gives an opportunity for a broad range of applications for Industry, for personal consumption and for society at large.

Concept

The term “Internet of Things” as quoted is, “an open and comprehensive network of intelligent objects connected to the Internet with the capacity to auto-organize, share data and resources, reacting and acting in face of situations and changes in the environment.” 

The “Things” in “INTERNET of THINGS”, refers to the sensing of an input, which may include transducers to transform energy, a simple electronic circuit or even a SoC (System on Chip), software to compute, mechanical elements as actuators, and/or connectivity to networks to transmit and receive the information. These sensors are also called NODES or Devices.

As we all know, “INTERNET” is the Information backbone for storage, access, and computation from anywhere and everywhere.

As an eco-system, IoT would have 2 networks

1. Local nodal network (Could be Bluetooth, Wi-Fi, Ad-hoc. RFID etc.)

2. IP (Internet Protocol)

If use cases do not demand internet access for information, storage and computation, the nodal network need not have a connection to an IP network in an IoT system.

Sensory systems without the power of internet could be as basic as localized and programmed actions such as, Thermistors to cut off a circuit upon a change in the temperature, Microphones to convert pressure to speech, proximity sensors to open the doors automatically or, a sophisticated PLC programming in Industrial automation.

But when this sense - automation is powered with a vast ability of Internet capabilities, the opportunities are endless for real-life experiences.

Diagram shown with nodal network access to the Internet

A real-world example of Dabbawalla of Mumbai could explain these nodal and internet networks in an analogous way.

Dabbawalla is a case study in Indian management schools which entails the description of the process of lunchboxes delivery from homes to offices with consistency of operations in scheduled times. This analogy could map Homes to Nodes, Offices to Recipient addresses, Lunch boxes to Data packets, Locality roads to Nodal networks, Local Train station to Internet gateway, and Local Train travel to Internet Data Transfer.

Packets/Boxes are collected at Nodes/homes by bicycles to carry them in Nodal networks/ Locality roads. Often multiple Nodal networks/Localities are crossed to reach the Internet Gateway/Metro station to travel further distances. Packets/Lunchboxes are received at the Local Network/ Destination Metro, to be delivered further to the Receiving Device/Receiver’s office.

The Data Packets/ Lunch Boxes gets identified, appended with addresses, coded, bundled, unbundled with staggered responsibilities, to ensure the entire transmission and reception process is error free . 

Communication

The data communication between sender and receiver was standardized with the 7 layer OSI (Open Systems Interconnection) model that links physical layer to the application layer through data link, network, transport, session, and presentation layers in that order.

The diagram below is OSI (Open Systems Interconnection) to explain the data transmission reception protocol.

Each layer has specific functions to perform to ensure end to end service that addresses packet loss, compression, connection, routing, security, etc.

As an example, Defective packages delivered will be resent by Amazon, while your morning newspaper is not redelivered in case of any defect. Former is an analogy for TCP (Transmission Control Protocol) and the latter, UDP (User Datagram Protocol) in the transmission layer. There is no error recovery in UDP. We can imagine that the Dabbawalla uses UDP protocol as they do not redeliver misplaced lunchboxes.   

Here Data Link and Physical layer is critical to devices in nodal network and MAC (Media Access Control) is a protocol in the Data Link Layer which is critical for IoT systems to ensure Data Packets reach the Internet Gateway, in time with the integration and synchronization intelligence.

Challenges

Key challenges listed below require core expertise to be developed to further evolve IoT eco systems. 

• Integration/Interoperability

Some IoT devices could be simpler to be connected while others may have a SoC (System on Chip) with a lean OS (Operating System).

IoT Nodal Networks can be using Bluetooth, NFC, Zigbee, Wi-Fi, RFID etc. and the network topology can be P2P, Ring, Star, Mesh, etc. configuration.

Platforms could have different access stacks like CSMA, Continki, TSCH etc.

• Security

It’s all about 4 elements Node/Device, Network, Access and Process. Since the IoT infrastructure is an amalgamation of sensors, gateways, hardware, and application software, it makes the entire system vulnerable to security breaches. All layers need to be addressed from device to cloud.

• Interference and multipath fading

This usually happens in a noisy network and signals reflected from other surfaces can cancel out each other.

• Latency constraints

For real-time use cases, data packets received in time can only be processed. This delay in data transfer can happen due to many reasons and one of them could be sub optimal scheduling for the devices to be woken up for data transfer.

• Loss of synchronization

It's applicable for synchronous media access control protocols where clock drift can create issues. This clock drift is an important issue when several iterations can make a milli-seconds difference to an order of few seconds.

How we address these challenges? 

Collaboration

IETF (Internet Engineering Task Force) is the body to come up with IEEE802.15.4 standard that specifies requirements for low data rate, low power, and battery-operated applications for wireless connectivity networks. This is to support industrial IoT at 2.4 Ghz bandwidth with a communication range of 10meters. IETF working group has standardized a set of protocols to enable low power industrial-grade IPv6 networks with MAC and PHY layers. IPv6 stack acts as the backbone to these layers to encapsulate these data packets to route it to the external world. It is a compressed version of IPv6 named 6LoWPAN (IPv6 Low Power Personal Area Network) to shorten the IPv6 address size for devices while external routers translate back these addresses back to IPv6 addresses. Its MAC protocol of Data Link Layer that is key for IoT device network access and control.

For Data Lank Layer, few standards are available that include,

1.      CSMA (Carrier-Sense Multiple Access): This is suitable for high bandwidth applications where the device’s radio is always on to exhaust its data transfer without low power constraints. This standard may not be suitable for a power saving IoT systems where battery charge needs to be saved with devices going to sleep mode frequently.

2.      Contiki: Contiki OS is used for asynchronous low power duty cycle. The device’s power saving is managed with nodes sleeping most of the time only to wake up periodically to sense the signal.

3.      6TSCH: This is the protocol used for global synchronization of all devices and network with time slot channel hopping mechanism. It is used for mesh networks with low power, reduced interference, high reliability, and security.

6TSCH is described in detail with the diagram below as a reference.

6TSCH standard proposes a protocol stack rooted in the Time Slotted Channel Hopping (TSCH) mode from the IEEE802.15.4-2015 standard. This integrated stack supports multi-hop topologies with the IPv6 Routing Protocol for Low-Power and is IPv6-ready with IEEE802.15.4e standard. This standardization allows the application of technology with a wide variety of sensors, network topography, control hardware, IP connectivity, etc.

TSCH guarantees network reliability by keeping nodes time-synchronized at the MAC layer of OS. This is achieved by scheduling so that sensor nodes remain time synchronized throughout the network session. Enhanced Beacon (EB) packets are exchanged frequently to secure this synchronization. Synchronization does not need explicit EB packets. Data packets may also be utilized to compute clock drifts and course correction of the schedule.

At its core, TSCH implements a channel hopping scheme that is popularly known as FHSS (Frequency Hopping Spread Spectrum) to reduce interference, remove multi path fading and to improve security.

Globally synchronized network nodes in TSCH mesh network will typically have a duration of several milli seconds. Slots are grouped in one or several slot frames, which repeat over time and form a schedule. Each slot is explicit in making nodes aware of its actions to remain idle, sleep, transmit or receive. TSCH combats interference through channel hopping at every slot. The channel is selected deterministically from a pseudo-random hopping sequence.

A new device when switched on activates a code to become a node in an IoT network. A joining protocol is implemented for this device so as to ensure that the device is joining an authenticated network and is of no security threat to other nodes. This is done by

1. Authentication,
2. Authorization and
3. Attributes (needed parameters such as registered IPv6 address).

TSCH incorporates a guard time to account for loss of synchronization with clock drift. This guard time covers both lead and lag clock drift by ensuring the receiver wakes up before the expected end of the transmission offset and keeps the radio on for some time or until a frame preamble is received for node synchronization. The guard time is equally spaced around the end of the Transmission Offset. The guard time gives the amount of synchronization error that can be allowed for a frame.

Further collaboration includes, computing anywhere and everywhere with node computing to cloud computing for latency issues, STBC (Space Time Block Encoding) or SDM (Space Division Multiplexing) for multi path fading issues, and IoT security with block chain capabilities.

Convergence

Today Industrial IoT is driving the use cases for higher productivity, efficiency and contact less process. Consumer IoT is largely driven from the point of personal consumption with commercial approach. The real convergence of technologies is expected to be with Social aspect of IoT which defines use cases that impacts society at large with return on equity. It democratizes the technology itself. Examples include Agriculture, Infrastructure, Government projects etc.

Applications of the three categories can overlap as shown in the Venn diagram.

Unlike Consumer or Industrial IoT, multi-disciplinary engineering efforts are significant in Social IoT.

Social IoT (Return on Equity): We have applications defined such as smart cities, smart metering, etc. but there is a scope for new PoCs (Proof of Concept) to expand the use cases further with government budgets and NGOs participation. The areas of expanded use cases could include Agriculture, Infrastructure, Transport, Healthcare, Space missions, etc.

As an example:

• Healthcare: The objective is to enhance quality of life by providing universally affordable healthcare costs and efficient solutions

-> Disease prevention

-> Managing chronic diseases

-> Hospitalization process and

->  Patient care

• Agriculture: To the needs of growing population, adoption of IoT could increase operational efficiency, lower costs, reduced waste, and increased yield and so on and so forth. The applications include

-> Precision Farming

-> Drone Management

-> Livestock monitoring

-> Smart Greenhouses

->  Intelligent supply chain

 Conclusion

The key feature of an IoT eco system is that, it is a converging point for many engineering disciplines and sciences. The purpose of Social IoT is to scale and sustain the IoT evolution with Return on Equity expectation in Pay As You Use Model. Challenges still remain for Interoperability of protocols for multi device multi nodal networks. The security framework for data transfer from devices to the cloud and vice versa is still evolving.

MAC layer plays critical role for critical functionalities and 6TSCH is one such standard that is promising to fulfil Social IoT wherein most of the use cases involve mesh networks, global synchronization of nodes, and low power. Social IoT brings Return on Equity with Pay As You Use model that leads to better governance of society and higher living standards for humanity. Future opportunities of IoT convergence lies with 5G connectivity, computing anywhere, Data Science, Robotic Manufacturing, AI, AR/VR etc. to create further use cases in the areas that include Agriculture, Healthcare, Infrastructure, Travel, Education and Climate Control.

When the purpose becomes larger, realization becomes nearer