The basic limitation of Bluetooth low energy is still a lack of popularity in home automation systems. And it is naturally so because Bluetooth SIG has only just introduced a mesh topology specification for BLE in July, 2017. Thus it is expected that Bluetooth Smart will overtake its nearest competitors (ZigBee and WiFi) and this limitation will be overcome for people who wish to use it in home automation systems without compatibility problems. Now let us speak a bit about the other technical limitations that BLE brings and how they might be overcome.
The biggest issue which might interfere with Bluetooth Low Energy becoming the protocol of choice is the bandwidth interference. BLE uses the same bandwidth (2.4 GHz) as your WiFi and regular Bluetooth, and ZigBee. The more devices you have on your frequency, the greater the interference and latency.
It is simple to determine if a wireless home automation system has a RF interference problem. Move intermittent devices closer together. If operation improves when the devices are close to each other, then you are probably experiencing RF interference.
There are several workarounds for this issue:
- Make the mesh richer. When using a wireless automation technology, having more devices improves system performance. Because wireless home automation works in a mesh network, adding more devices creates additional pathways for the signals to travel from source to destination.
- RF signals weaken quickly over distance (by inverse square law). You can use devices with a stronger output power to overcome this. It helps to increase the distance the signal can travel between devices in the network.
- Move a device to a new location. To manage the risk of interference between similar protocols, it’s best to keep all BLE devices some distance away from wireless routers and other sources of radio interference (like microwave ovens).
No Direct Voice Commands
BLE devices do not work with large amount of data. They can transmit only up to 100 kbps and then only for very short period of time. A person can’t give a voice command directly to a heating device, for example.
Nevertheless there are other intermediary devices that convert voice commands to a short byte set and transmit it to the BLE devices. It’s all about voice assistants and hubs.
Wireless audio products, like speakers, use Bluetooth Basic Rate/Enhanced Data Rate (BR/EDR), which is designed for continuous wireless connections and is optimized for audio streaming. Bluetooth mesh networking uses Bluetooth LE, which is designed for short-burst wireless connections. The mesh networking specification is only available for Bluetooth LE and does not support audio streaming.
While Bluetooth has been around for 22 years, it has only recently entered the Home Automation industry and thus does not have many options available to the consumer. In addition, many hubs do not yet support Bluetooth LE at this time. We reviewed 5 smart hubs from different manufacturers (Samsung, Iris, Wink, Phillips and Orvibo) and only one of them supports Bluetooth Low Energy. Today this is a strong limitation for people who want to organize their home space using BLE.
Of course you’ve heard about hacker attacks using IoT devices. The main message is simple: an IoT network has weak security protocols for the present. And there is only one thing protects your network: that is your attention. Smart home privacy and security is the most sensitive issue in the Smart Home context. For example, while you unlock a door somebody could intercept radio waves between a smartphone and smart lock using a sniffer which costs in the range of $50-100.
BLE protocol does support a good security level but it must be implemented. As other similar protocols BLE is susceptible to such security issues as passive eavesdropping such as Man in the Middle (MITM) attacks and identity tracking. But starting with the 4.2 spec version Bluetooth SIG payed due diligence to providing higher privacy and security options. Thus the problem is to implement it.
To avoid being hacked take into account the following advices:
- Buy only BLE devices with proven trademarks.
- Be careful with third-party applications. Install only applications from trusted companies.
- Install a Network Firewall. The security protocols for some smart home devices are still not secured enough. A good home network firewall will protect and encrypt all incoming and outgoing data.
Mesh is Not a Problem Now
Until the middle of 2017 BLE worked only with star topology. But at Jun, 28 Bluetooth SIG introduced the support of mesh networking. The spec allows it to support up to 32,000 nodes. Mesh networking is now compatible with core specification version 4.0 and higher. Chips should support the GAP Broadcaster and Observer roles, to both advertise and scan for advertising packets. BLE mesh is secure (AES-CCM and 128-bit keys applied) and promises to maintain the same low energy consumption as previous BLE processors.