Bluetooth 5 Expands into the Smart Grid



Why Bluetooth Low Energy features match industrial’s speed, power, and toughness demands

As the new standard version of Bluetooth has emerged, Bluetooth Low Energy, or BLE, is now moving from applications historically centered around personal electronics and wearables to industrial applications. The smart grid can take advantage of this worldwide standard for various use cases, including utility meter applications, where robustness, distance, communication speed, and ultra-low power are important.

With Bluetooth however, any smart meter in the world could connect to a smartphone or tablet.

Figure 1: Now available to developers are solutions and expertise that make adopting Bluetooth Low Energy (BLE) for the smart grid timely and practical.

Figure 1: Now available to developers are solutions and expertise that make adopting Bluetooth Low Energy (BLE) for the smart grid timely and practical.

In addition, through devices such as a smartphone or tablet, BLE can enable anyone in the world (a consumer or maintenance specialist, for example) to interact with a smart meter, making it a ubiquitous complement to the various wireless technologies already used in this space. So, let’s look at what Bluetooth 5 is, its potential use cases in the smart grid space, and how current offerings will help you quickly implement this new standard.

Wider Coverage
Bluetooth is an established standard driven by the Bluetooth Special Interest Group (SIG) and is today’s leading connectivity technology in terms of volume shipments and installed base. It is one of the fastest-growing wireless technologies according to ABI Research. Before Bluetooth 4.0, devices connecting to phones or computers had mostly been limited to audio headsets or human interface devices (HIDs) (mice, keyboards and other applications) using Classic Bluetooth for streaming audio or transferring large packet sizes at a high data rate. The primary limitation for Classic Bluetooth was its comparatively high-power consumption, which made it limited for low-power applications using coin cells or other batteries.

BLE resolved this issue, and now a broad range of solutions using low-power technology has opened up the possibility of new application profiles. Since the Bluetooth 4.0 specification, Bluetooth low energy technology has seen exponential growth in many applications, primarily in personal electronics and wearables—end equipment surrounding the end user in what’s known as a “personal area network” (PAN). The next use case for Bluetooth Low Energy will be in the industrial realm, where the top concerns range from robustness, to communication speeds, to range, to low power. With the new Bluetooth 5 standard delivering two times the bit rate (up to 2Mbps) and four times the distance compared to Bluetooth 4.0, BLE is ready to move from PAN coverage to wider house and building coverage or local area networks (LANs).

Smart Grid Potential Use Cases
LAN typically designates premises and surroundings of up to hundreds of meters, while the wide area network (WAN) is more in the range of several kilometers. The smart grid space is a patchwork of different wireless communication standards driven by local governments and regulatory bodies including the proprietary Sub-1 GHz industrial, scientific, and medical (ISM) band, Wireless meter (M)-Bus and 2.4 GHz Zigbee, with no worldwide interoperability and common standard. With Bluetooth however, any smart meter in the world could connect to a smartphone or tablet.

Bluetooth 5 enables longer distances while maintaining low power and offering higher throughput, better noise immunity and coexistence with other wireless devices. So, is this the beginning of many new applications for Bluetooth in the smart grid space? Regulatory bodies and energy institutes will certainly have a say on new specifications for the next smart meter generation, but Bluetooth 5 is generating a lot of interest.

Bluetooth Low Energy could be the perfect link from the meter to the user. Using the phone as a display, for instance, is a very economical way to interact with a smart meter; there’s no need for a meter manufacturer to break his entire design to add a liquid-crystal display (LCD) or a more advanced display, and no need for a user to install an in-home display. For maintenance and data-logging purposes, BLE could replace infrared technology or proprietary protocols in operator equipment. With the new high-speed mode (2Mbps), Bluetooth 5 enables faster data transfer: it extracts data from applications more quickly, opening up options for on-site diagnostics or faster firmware upgrades. The transmit time is shorter, which lowers the power consumption compared to Bluetooth 4 for the same amount of data exchanged, making it more robust as well.

Countries like India, where pre-payment is popular, are looking at using Bluetooth Low Energy to have phones talk to meters and accept pre-paid credit to access energy. Should security be a concern, Bluetooth 5 carries over the security improvements from Bluetooth Low Energy 4.2, such as secure pairing and privacy, with encryption techniques that can help developers implement their security measures.

Bluetooth Low Energy can also make the perfect standard bridge for other protocols to help maintenance workers to communicate via the Sigfox network or other networks with a phone; some module manufacturers are producing BLE to Sub-1 GHz bridge solutions for this purpose.

Accessing the meters is key, and having enough outdoor or indoor range coverage to monitor the meter is important. The achievable range is a function of many parameters specific to each use case and situation, but Texas Instruments (TI) has performed Bluetooth 5 testing on its SimpleLink™ Bluetooth Low Energy CC2640R2F wireless microcontroller (MCU) and demonstrated a 1.5km line of sight while maintaining low power from a coin-cell battery or covering the full range of a 400m building.

You might ask, why not just increase the transmit power to achieve a longer range? While increasing the output power will almost always result in a greater range, a higher transmit power equates to higher peak currents on the battery, which substantially degrades the useful life of small (coin-cell) batteries that power today’s small embedded devices such as smart meters.

To solve this problem, Bluetooth 5’s long-range capability comes with the addition of new coded physical layers (PHYs), improving receiver sensitivity through the use of forward error correction (FEC) techniques that protect data during transmission at the expense of lower data rates. This encoding with coded PHYs reduces data rates down to 128kpbs from the 1Mbps data rate in the Bluetooth 4 low energy specifications. The use of coded PHYs increases the range by improving the link budget without increasing transmit power, thus enabling the use of smaller batteries. Smart meters, which typically exchange data in the range of tens of kilobits per second, work well with the 128kbps data rate available in Bluetooth 5. So, the Bluetooth 5 long-range mode can definitely be an attractive feature if you’re considering adopting Bluetooth low energy in smart grid applications with uncompromising low-power budgets.

Technical Challenges and Implementation
Adding wireless connectivity to an existing application comes with many challenges and a smart meter designer will have to go through the hardware and software considerations to make this process as smooth and seamless as possible. Like many industrial applications, the smart meter already contains a host microcontroller, fully tested, sometimes certified or qualified to certain regulatory standards, already connected to a metrology device and possible other WAN radios. It is quite typical that designers will adopt Bluetooth 5 by adding a BLE companion chip to their application communication onto the main host MCU. This is for faster implementation, or simply because several meter models may or may not feature Bluetooth and designers will look at keeping the system flexible. The resulting software split and impact on the application will need to be evaluated and different techniques can be adopted. Ranging from easy to design with QFN packages to fully certified modules, wireless MCU and wireless network processor software implementation, designers now have the choice of many package alternatives to make the integration process easier.

Conclusion
The Bluetooth 5 standard is now delivering the necessary conditions for a wider industry adoption beyond consumer and personal electronics. From a technical standpoint, it delivers higher speed, longer distance, and more robustness while maintaining low-power operation. For data logging, diagnostics, and commissioning, for instance, Bluetooth 5 is a promising economical companion for wireless technology for the smart grid, with the potential for worldwide deployment, and supported by an infrastructure of existing smart devices.

References


Olivier-Monnier-r300Olivier Monnier is Wireless Connectivity Solutions marketing and business manager at Texas Instruments. Prior to this role, he spent 16 years in various positions at TI, including worldwide smart grid marketing and business manager, starting as an applications engineer for digital signal processors and microcontrollers. He graduated in energy conversion and power electronics at the École Nationale Supérieure d’Electricite et de Mecanique (ENSEM, Nancy). He has more than 15 years of experience in industrial and energy related applications.

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