July 11, 2017 15:19
Bluetooth 5.0 enhances IoT experience
Bluetooth 5 improves the IoT experience with twice the speed, four times the range, and eight times the advertising capacity for long range, more robust connections, and eight times advertising capacity with smarter beacons. Plus, Bluetooth Low Energy (BLE) is optimised for devices that run for long time periods on battery power, coin-cell batteries.
Bluetooth 5.0 Evolution
The latest Bluetooth standard improves bandwidth, range, broadcasting, and coexistence features.
Speed is one of the major features in Bluetooth 5 with a new 2 Mbps PHY. Bluetooth 4.x devices support a single 1 Mbps PHY rate. Bluetooth 5 devices are capable of supporting either the 1 Mbps or 2 Mbps PHY rates. By doubling the PHY rate, the amount of data that devices can transfer is almost doubled. The faster PHY reduce time for transmitting and receiving data, which results in power savings by lower average current consumption. Lower packet time translates to extended wireless battery-powered device operation. Also, faster data rate enables field-upgradeability by deploying Over-The-Air (OTA) firmware updates. Table 1 illustrates data rate effects on packet time.
Table 1. Bluetooth 5 data rate
Range extension of up to four times can deliver more robust connections for indoor home and building coverage, and outdoor line-of-site applications. The LE coded PHY uses a unique packet format which improves RX sensitivity as well as improved range. The 4x range improvement is derived by 4-6 db sensitivity improvement at the 500 kbps or 125 kbps PHY data rate. Bluetooth 5 also adds Forward Error Correction and Pattern Mapper. Table 2 shows Coded PHY kbps effects on range and packet transfer time.
Table 2. Bluetooth 5 – Coded PHY data rate effects on range and packet time
Antenna efficiency is a major factor in extending range. Antenna efficiency is a specification that describes the total amount of RF energy radiated into the air compared to the RF energy delivered into the antenna. The efficiency is an approximation of the average range regardless of the device position. With an optimal antenna design it is possible to achieve a -1dB antenna efficiency. Antenna performance depends on the PCB and mechanical layout around the antenna. Typical antenna efficiency is -5 dB. Table 3 shows the EFR32BG12 Bluetooth SoC Tx Power and Rx sensitivity levels at different data rates.
Table 3. EFR32BG12 Bluetooth SoC Transmit Power versus Link Budget and Range
Bluetooth 4.0 or Bluetooth Smart introduced Bluetooth low energy (BLE) features in 2009. BLE enabled beacons to be deployed on a broad-reaching scale. Beacons are small Bluetooth transmitters that can send data to any other Bluetooth low energy technology-enabled devices such as smart phones and tablets within their range. Advertising allows devices to broadcast information defining their intentions. Bluetooth 5 enhances advertising with the addition of LE Advertising Extensions, which allows a single Bluetooth 5 device to send out multiple individual advertisement data sets with unique intervals and advertisement data. A device enables a single Bluetooth beacon to transmit individual Apple iBeacon and Google Eddystone beacons simultaneously. A Bluetooth 5 compatible advertiser can also detect when a scan request is made by a remote device and report the request to the application level.
Finally, Bluetooth is a point-to-point network architecture, which can limit the range of the network. Bluetooth 5 will soon support mesh networking. The Bluetooth Special Interest Group (SIG) will reportedly launch the Bluetooth Mesh specification in 2017. Mesh networks topology allows each node to relay network data, which can extend the network range by just hopping from node to node. Mesh networks also have the added benefit of being ad hoc, meaning nodes can be added or removed with limited network reconfiguration. Mesh networks are ideal for wireless sensor, lighting, and beacon applications in home, retail and building automation. Mesh networking is supported in the Bluetooth 5 software stack, which allows for the upgrade of Bluetooth 5 ready hardware (SoCs and modules) to support mesh. Expect announcements from SIG later on Bluetooth Mesh support later this year.
Silicon Labs recently launched their first Bluetooth 5 compatible Wireless SoC, EFR32BG12 Blue Gecko, supporting the Bluetooth LE 2M PHY and some of the advertisement enhancements.
More information and more detailed specifications of the Blue Gecko SoCs and modules can be found from http://www.silabs.com/bluegecko.
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