The Essentials of Smart Home Security
According to Forbes, it is estimated that total spending on Internet of Things (IoT) devices and infrastructure will reach $1.2 trillion by 2022—up from an estimated $151 billion last year. Such rapid growth indicates that the IoT is penetrating deeply into many markets, from first adopters a decade ago to today, where 90% of business executives in technology, media and telecom consider IoT technology to be central to their business strategy.
When you consider that one of the major bottlenecks to widespread IoT adoption and development has been the rapidly evolving radio frequency (RF) technology landscape, it’s clear that companies should start investing in this ever-growing space with scalable and flexible microcontroller (MCU) platforms.
One of the fastest growing IoT spaces is in the home network. The “home network” includes products that work together seamlessly to provide both a smart and secure home experience. Inside today’s smart home products and talking home assistants, however, is a much more sophisticated and intricate story. The smart home market is fragmented at several levels, making device interoperability a challenge.
At one level, the smart home consists of several sub-categories such as building security, heating, ventilation, air conditioning (HVAC) and fire safety systems. Anyone who even casually follows the smart home market has seen the rapid growth of the building security sub-category with the influx of out-of-the-box security systems available for homeowners to purchase. These security systems ship directly to the front door and are immediately ready to install by the homeowner.
When designing a smart home security system like this, flexibility and scalability are paramount. Meanwhile, interoperability, given the need for multiple peripheral devices, can be a major challenge. To overcome these design challenges, security service providers and security system companies are working to make products interoperable out of the box by integrating the essential components illustrated in Figure 1. These components can be divided into these three categories:
- Sensing, including door and window sensors, motion detectors and glass break detectors.
- Monitoring, using security cameras and video doorbells.
- Control (both local and remote) using gateways, access panels, electronic smart locks, cloud-based dashboards and smartphone apps.
The requirements for implementing sensing, monitoring and control into a security system differ, making it increasingly challenging for security system companies to keep up with and stay ahead of the needs of all three functions while minimizing additional design time and effort.
Let’s review what security providers should prioritize when developing a smart home security system.
Sensing priorities: long range and low power: We all know a person’s homestead is typically the largest asset on their balance sheet. At the same time, it also provides storage for a plethora of personal valuables. The interest of homeowners to easily protect their assets with low hassle is driving the need for security companies to provide solutions that can both secure all of the entry points of a home as well as enable the least amount of upkeep maintenance as possible.
Long range enables homeowners to place a sensor in remote and hard-to-reach locations, such as a window on the third floor of a home, therefore extending coverage to areas previously unreachable by wired systems. Enabling greater coverage through extended range in turn increases the number of connected sensors in a home as well as the burden for homeowners to monitor battery life and battery replacement cycles. By creating lower power sensors, battery life can be elongated to multiple years, therefore reducing the maintenance burden on the homeowner.
Sub-1 GHz is currently the leading technology for sensors due to its extremely long range, ability to penetrate walls and low-power capabilities. Because there are no standards bodies currently overseeing the Sub-1 GHz bandwidth, many developers must create their own proprietary protocols from scratch, requiring significant R&D investment, time and RF expertise. Some silicon providers will make this investment for security system developers and provide an out-of-the-box toolkit to help them get started in Sub-1 GHz design.
Zigbee and Thread are 2.4 GHz mesh standards. Zigbee enables ultra-low power through Zigbee Green Power, which supports battery-less devices by enabling sensors that can harvest mechanical energy from movement, such as opening a door or window sensor. Thread is designed specifically for home networks and is based on Internet Protocol ver. 6, which enables Thread devices to have an easy connection to existing networks.
Monitoring priorities: high throughput and security: If a picture is worth a thousand words, video is worth a million —when it comes to home security, that could not be more true. Wi-Fi is typically used to achieve the throughput required to stream video from monitoring home entry points. Choosing a Wi-Fi MCU that can support 4 Mbps or more is important to enable 1080p video streaming.
In addition, monitoring undergoes extra security scrutiny from home/building installers, as the information being stored and/or sent over the air is more sensitive. Selecting an MCU that has comprehensive end-to-end security, from storage to run time to transfer, can further help secure a monitoring design.
Control priorities: multiprotocol concurrency and remote control: Multiple wired and wireless connectivity standards enable connections to wireless sensing and monitoring functions, and for large buildings, wired connections back to a central server.
A combination of wireless technologies, such as Wi-Fi, Bluetooth low energy, Zigbee, Thread and Sub-1 GHz, and a wired connection, such as Ethernet, are commonly used for control. Combining multiple wireless technologies in a single control component requires both multiprotocol concurrency and coexistence.
Enabling multiprotocol concurrency on a single MCU can be done by developing software that switches between protocol stacks in real time based on protocol priority tables. Developing low latency multiprotocol managers helps enable the control unit to interact in multiple networks at the same time while also ensuring successful packet transmissions due to the fast switching time.
Supporting coexistence on two 2.4 GHz MCUs, such as a Bluetooth MCU and Wi-Fi MCU, is another important design aspect to consider. By using time division multiplexing, the two MCUs can share the same antenna and reduce the bill of materials (BOM) of a design. In addition, by designing with Bluetooth and Wi-Fi, homeowners have the ability to remotely access and control their smart security system, with Bluetooth providing shorter-range remote access through the phone and Wi-Fi providing remote access through the cloud.
SCALABILITY AND FLEXIBILITY
There are many dominant and newly emerging connectivity solutions that aim to meet sensing, monitoring and control requirements. However, with the increasing number of connectivity solutions and system requirements, it has become increasingly difficult for security system companies to stay up to date with market demands, such as longer range, lower power, faster networks and greater security, without having to divert additional resources toward system redesigns.
Selecting an MCU platform that supports both wired and wireless connectivity protocols enables code reuse through common software development kits and application programming interfaces. Security system companies benefit from more flexible and scalable designs, further enabling them to stay ahead of market needs.
PUBLISHED IN THE CIRCUIT CELLAR MAGAZINE • November 2019 #352 – Get a PDF of the issueSponsor this Article
At Texas Instruments, Michelle Tate serves as a product marketing engineer for the SimpleLink connected MCU team, specializing in building security systems. She received her bachelor’s degree in electrical engineering from The University of Texas at Austin.