Editor’s Note: Welcome to our weekly Reality Check column. We’ve gathered a group of visionaries and veterans in the mobile industry to give their insights into the marketplace.
In the 1980s, the proliferation of the personal computer was a disruptive technology that changed the way we live, work and play. In the 1990s the Internet made its debut, impacting the lives of people all over the world. With the 2000s, the “Internet of things” began entering our consciousness and is on its way to become the next major disruptor. The introduction of low cost wireless sensor and control networks that will be used by the IoT, which is sometimes called machine-to-machine, can detect a condition and respond immediately, allowing them to prevent waste, improve quality, lower costs, provide new conveniences and, in some cases, save lives.
Developers of these IoT systems have tremendous opportunities in adding wireless sensor network capabilities to existing product lines or creating new products that will change our lives for the better. The proliferation of low cost wireless sensors is a revolution that is occurring in the background. Most people will never be aware of the sensors that are already all around them, from occupancy sensors and motion detectors that control lights and temperature to the sensors in their automobiles that determine whether or not to engage the airbag on the passenger side. Most of these sensors work so well they’re only noticed when there is a failure and this can create a negative impression about this powerful and positive technology shift. Therefore, it is imperative that we make the best choices in the selection of wireless sensor networks.
There are three criteria that any developer should look for in a wireless sensor network. First, the network should be highly reliable. Second, it must offer high security and third, it must be based on an open global standard. Some may focus on considerations, such as cost, performance, power budget, etc., but these factors often lead to false economies without greater emphasis on the three criteria.
Anyone who has started a mobile phone conversation only to have the call drop after entering an elevator or underground garage can attest to the challenging nature of wireless communications. Wireless sensor and control networks don’t generally have the luxury of being able to move transceivers to a new location when signals are blocked or when there is interference. About 10 years ago a group of engineers that understood this limitation created the IEEE 802.15.4 specification which uses offset-quadrature phase shift keying (O-QPSK) along with direct sequence spread spectrum (DSSS). Together these two features provide great performance in low signal-to-noise ratio environments. Many of these same engineers then went on to form the ZigBee Alliance to create standards for network layers above the physical (PHY) and media access control (MAC) that were covered in IEEE 802.15.4. ZigBee Alliance included features such as carrier sense multiple access-collision avoidance so that a ZigBee radio will listen to find a clear opening before transmitting. Each over-the-air packet will retry three more times after the original transmission if it does not receive an acknowledgement that the transmission was received. By combining all of these features, you can create very robust, reliable networks that are easy to use.
A main feature offered by ZigBee is mesh networking, which increases the range of a network by allowing multiple hops between radios to carry packets that are typically far beyond the area of a single radio signal. Mesh networking creates ad-hoc networks that are self-healing and self-forming with automatic route discovery. Any radio can communicate with any other radio in the network, as long as there are other radios within range that can route the signal. If a radio in the path fails, or the signal is blocked, the mesh network automatically finds a new route to its destination and the network keeps working. When more radios are within range of each other, there are more alternate paths, allowing the network to become even more reliable.
As wireless sensor networks become more common, they can unfortunately become targets by hackers and vandals in the same way as our laptop and desktop networks. Last year, at the renowned hackers’ conference called DefCon, a hack demonstrated changes to a wireless insulin pump that could lead to the death of a diabetic patient. It goes without saying that attacks on wireless sensor and control networks can be annoying at best, extremely costly or life threatening at worst. To provide effective security, ZigBee employs both authentication and encryption. The NIST Advanced Encryption Standard AES-128 is used by ZigBee to encrypt packets so that they cannot be easily decoded by a device listening to the network without the key. Additional encryption is used in other ZigBee networks to allow encryption among specific devices in the network. ZigBee then takes it a step further and uses authentication to prevent replay attacks or the injection of false packets into the network.
Wireless sensor networks based on an open global standard have several advantages. With ZigBee, there is a rich ecosystem of providers offering all the software, tools and components you’d need to create a product. From transceiver-microprocessor combinations, network stacks, modules, integrators, test harnesses and other tools, you can find it within the ZigBee Alliance. The combined knowledge of all of these organizations working together leads to better solutions and shared knowledge. The competition leads to better prices and unique features, protecting you from the whims or viability of a single-vendor for your product life cycle. Best of all, you can have interoperability among devices from different vendors within every ZigBee Alliance application standard. This means a variety of products can be included in the same network with greater utility, stronger mesh networks and all at a lower overall cost. Today the ZigBee Alliance has more than 400 members and already has 600 ZigBee Certified products available, with many more in development proving that strong ecosystems allow for faster product development.
As wireless sensor and control networks continue to gain a foothold in our lives, and the IoT, remember to consider the three important criteria when determining the right technology combination: reliability to ensure the information will get through in a timely manner and that the network will continue to function; security to safeguard the network sensor and control components from compromise and an open global standard to assure interoperability among products from a wide range of suppliers. With these three criteria, everyone can continue to build wireless products that work so well, they remain relatively unnoticed by the vast majority of the people whose lives they are improving.
Tim Gillman has over twenty years of experience in embedded systems firmware and software. Gillman is an active member of the ZigBee Alliance Work Groups, is secretary of the ZigBee Core Stack Group and Vice Chair of the ZigBee Smart Energy Work Group. He has an MBA from Oregon State University.
