Will LTE kill Home Automation?

This week I've spent a lot of time discussing the hardware options for our next generation home automation controller. It all looks fine on paper. We will include this and that radio module and this and that port and so on. But as the options are (almost) set in stone now, digging down deeper into the electronics and layout of the radio modules, I realized there is one significant risk coming, which we have to add to our equations.

The risk is called LTE, or LTE 800 in particular. The frequency arrangements for the 800 MHz band (covered by the ECC Decision 2010/267/EU) assume Frequency Division Duplex operation with the downlink (a tower to a modem) located in the lower 791-821 MHz band and the uplink (a modem to a tower) located in the upper 832-862 MHz band.

The uplink LTE 800 band is awfully close to the 863-870 MHz band assigned to various Short Range Devices, including many home automation standards in Europe (Z-Wave, 6LoWPAN, EnOcean). There has already been reports published (see this and this) discussing the interference between the LTE 800 and various types of SRDs (Short Range Devices) operating in the 868 MHz band. Talking to the home automation equipment vendors I can see most of them are aware of the problem. But as much as they are aware, there has not been much they have done to combat the problem. They all say the problem is difficult to resolve.

More importantly, the LTE interference problem can be resolved only in new designs, the earliest coming probably a year from now to the market. The equipment already purchased by consumers may just stop working reliably as soon as a local Mobile Network Operator powers up an LTE 800 base station nearby.

Unfortunately the LTE poses a risk to the entire home automation market in Europe. Depending on how this issue is communicated to consumers, they may just build an opinion the Short Range (radio) Devices are simply unreliable and do not work. And surprisingly this development may give some advantage to other SRD standards, especially those operating in the 2.4GHz band (ZigBee, Bluetooth and some 6LoWPAN implementations). 2.4GHz has always been full of interference and those systems have already formed some level of immunity to interference.

It will be interesting to watch how the story evolves. The issue certainly has to be taken into account when designing new systems. But the real problem in my opinion is with the equipment already present and in use, as users will certainly be affected by the LTE interference to some extent. In every smart home system implementation I've seen, there are remote modules on the edge of the coverage of a HA network. They do not require much interference to break the link permanently. So potentially every user will be affected. And there is no simple cure. You cannot "just crank up the power" (these networks already operate at maximum power allowed). So a redesign and realignment of topology is needed, more repeaters, physically realigning repositioning the units (where possible) and so on. All in all: a big disturbance ahead of a young, still fragile and growing market. We have to address it to minimize the impact.