Bluetooth low energy is enabling long-range IoT
Bluetooth has traditionally been viewed as a short-range technology for audio and personal area networks. Bluetooth® Low Energy (BLE) however is being adopted in a wide array of industrial and commercial/ consumer IoT applications like sensor nodes due to its low power consumption. Several industrial/commercial applications are leveraging BLE for its ability to simply transmit data over a long range to a hub and/ or a smartphone – without consuming large amounts of power. Cypress has several solutions to enable both low-power and long-range BLE connectivity. This Design Note focusses on Cypress’s new long range Bluetooth modules and how they allow for innovative industrial and consumer/commercial applications.
Long-range connectivity for industrial applications and lighting
A simple application that needs long range connectivity is a beacon on a piece of industrial equipment in a factory/assembly line. The beacon transmits status data a few times a day to a hub. The hub receives such data from multiple pieces of equipment in the factory and therefore may be located at a distance of 100 meters or more from several of them. When an error is noticed in the status data from a particular piece of equipment, a technician is dispatched to that location who then uses a smartphone to get detailed data logs. A BLE device in this use case would be wall powered and should be able to transmit data over a long range using BLE advertisements with higher transmit power. The BLE device would also be used to connect to the technician’s smartphone for detailed data logs using a custom profile similar to Bluetooth Classic’s Serial Port Profile. Since the BLE device is being deployed in an industrial environment, it may also need to tolerate temperatures of 90°C to
100°C to match the operating ambient temperatures in the vicinity of the industrial equipment.
Another application that requires long-range connectivity is lighting. Industrial LEDs and even some commercial/consumer lights come with smartphone apps to turn the light on/off. In some cases the app provides options to set the colour and even the intensity of the light. In this use case a BLE device inside the light fixture would need to maintain a long-range connection with a smartphone to exchange relevant data. In addition, since the temperature of several of these light fixtures can go higher than ~90°C, the BLE device would need to tolerate higher temperatures and maintain functionality throughout any fluctuations.
EZ-BLETM PSoC® modules enable the industrial IoT
Cypress’s EZ-BLE PSoC Module, CYBLE-224110-00, is an ideal fit for industrial/lighting applications that need long range and high temperature tolerance. The module is fully-qualified to Bluetooth 4.1, fully-certified to FCC, IC, TELEC, KCC and CE, and integrates a PA and LNA to support long range and an extended industrial temperature grade of -40°C to 105°C. The PA enables an output power of 9.5dBm with the on-board chip antenna while the LNA enables best-in-class receive sensitivity of up to -95dBm. Together the PA/LNA enable a line-of-sight range of up to 400 meters in an open-air environment or ~100 meters in a typical home/ office environment. For industrial/lighting applications that need better over-the-air security and/or higher throughput in addition to long range and high temperature tolerance, Cypress’s CYBLE-224116-01 provides all the optional Bluetooth 4.2 features. These include:
• LE Secure Connections using Elliptic Curve Diffie-Hellman algorithm for secure key exchange
• LE Extended Data Packet Length for 251byte over- the-air payload (compared to 27bytes in BT 4.1) that enables up to ~800kbps throughput (compared to ~300kbps with BT 4.1)
• LE Privacy 1.2 for power- efficient address resolution
Long-range connectivity needs for consumer/commercial IoT system design
Many applications outside of the industrial space also require and benefit from long-range connectivity. Commercial applications like asset tracking in warehouses require long-range wireless communication to a central hub or smartphone. Home/electronic appliances may also require long-range capability simply because the obstacles in a typical home/office environment reduce the range of Bluetooth.
The presence of obstacles can result in multipath fading that reduces the range of a Bluetooth module with 0dBm output power from ~30 meters line-of-sight to ~10 meters. Using a long-range module enables 80 to 100 meters of range even in a home/office environment and ensures Bluetooth communication throughout the building.
EZ-BLETM PRoCTM modules enable commercial and consumer IoT
Cypress’s EZ-BLE PRoC Module CYBLE-212006-01 is the perfect fit for commercial and consumer IoT applications that require long range. The module is fully-qualified to Bluetooth 4.2, fully-certified to FCC, IC, TELEC, KCC and CE and integrates a PA for 7.5dBm o/p TX power and an LNA for up to -93dBm receive sensitivity with an on-board PCB antenna. Bluetooth 4.2 as mentioned earlier ensures better security and higher throughput for IoT applications.
|Module MPN||Size||BT Spec||Antenna Type||Application||Evaluation Board|
|CYBLE-224110-00||9.5 x 15.4 x 1.80mm||BT 4.1||Chip Antenna||Industrial (-40°C to 105°C) Automation/Lighting||CYBLE-224110-EVAL|
|CYBLE-224116-01||9.5 x 15.4 x 1.80mm||BT 4.2||Chip Antenna||Industrial (-40°C to 105°C) Automation/Lighting||CYBLE-224116-EVAL|
|CYBLE-212006-01||15 x 23 x 2.00mm||BT 4.2||PCB Antenna||Consumer (-40°C to 85°C) and Commercial||CYBLE-212006-EVAL|
|CYBLE-202007-01||15 x 23 x 2.05mm||BT 4.2||External Antenna via u.FL||Consumer (-40°C to 85°C) and Commercial||CYBLE-202007-EVAL|
|CYBLE-202013-11||15 x 23 x 1.55mm||BT 4.2||External Antenna via RF Pad||Consumer (-40°C to 85°C) and Commercial||CYBLE-202013-EVAL|
Every application is different, and Cypress’s new BLE modules cover a wide spectrum of design needs. Certain consumer and commercial applications require the Bluetooth module to be placed inside a metal enclosure and therefore require an antenna that can stick out of the enclosure for wireless communication access. Other applications may simply want an external antenna option for better gain to further improve range. The CYBLE-202007-01 provides an option to attach an external antenna via an on-board u.FL connector while the CYBLE-202013-11 enables an external antenna using a RF solder pad. Both of these can support external antennas with 50Ω impedance.
Bluetooth 5.0: new long range features
The new Bluetooth 5.0 specification provides a number of new optional features like the 2Mbps PHY for higher BLE throughput and advertisement extension for longer BLE advertisement packets. It also includes two features which promise to further improve the range of BLE:
1. LE Long Range: This feature uses Forward Error Correction (FEC) to improve the receive sensitivity. FEC however does not improve the TX power. FEC uses a coded PHY that encodes every bit of outgoing information using two or eight symbols. Effectively this reduces the PHY data rate from 1 Mbps to 125kbps, when using eight symbols per bit, or 500kbps, when using two symbols per bit. FEC only helps in long-range communication between two devices when both devices support the coded PHY. Existing smartphones/hubs will not be able to use this feature for long-range communication. Another concern with FEC is that applications will require more time to transfer the data, will use the spectrum for a longer period of time and may effectively burn more power. An external PA/LNA-based Bluetooth module, such as the Cypress modules discussed here, may actually offer more power efficiency. Finally, because this feature results in a BLE device occupying the spectrum for a longer time period, coexistence will be a major issue for IoT devices using both BLE and Wi-Fi.
2. Higher LE TX Power: The maximum TX power allowed for BLE is now 20dBm. This is expected to drive new BLE modules that can provide even longer range than the 400 meters line-of-sight, open-air range possible with today’s best-in-class modules. Note however, that certain regions of the world, such as Europe, do not allow a FHSS- based wireless technology like Bluetooth to transmit at power levels over 10dBm. All of Cypress’s long-range modules covered in this article are capable of transmitting at higher power levels using firmware/software settings. Designing with these modules therefore ensures a future-proof design that can leverage higher transmit power levels if and when allowed by regulatory bodies. FCC in the USA and IC in Canada already allow up to 20dBm power level for Bluetooth and customers in these countries can get even longer range with Cypress’s long-range modules.
Both Bluetooth 5.0 features provide longer range at the cost of an increase in power consumption depending on the application use case.
Cypress’s EZ-BLE PSoC Modules discussed here consume 26.3μA on average for a 1-second connection interval with long-range communication when transmitting at ~9.5dBm output power. It remains to be seen how the new Bluetooth 5.0 features affect power consumption numbers and whether they are broadly adopted for real-world IoT use-cases.
Orderable Part Numbers: CYBLE-224110-EVAL, CYBLE-224116-EVAL CYBLE-212006-EVAL, CYBLE-202007-EVAL CYBLE-202013-EVAL