Bluetooth – POTs and PANs

Amazon’s Huge IoT Network

In a recent blog post, Amazon invited developers to test drive its gigantic IoT network. This network has been labeled as Sidewalk and was created by tying together all of Amazon’s wireless devices like Amazon Echos and Ring cameras.

Amazon claims this huge wireless network now covers 90% of U.S. households. Amazon created the network by transmitting Bluetooth and 900 MHz LoRa signals from its various devices. This network provides a benefit to Amazon because it can detect and track its own devices separate from anything a homeowner might do with WiFi.

But Amazon has intended for years to monetize this network, and this announcement begins that process. This network has been under-the-radar until now, and most homeowners have no idea that their Amazon devices can connect and communicate with other devices outside the home. Amazon swears that the IoT connection between devices is separate from anything happening inside the house using WiFi – that the IoT network is a fully separate network.

Anyplace where there are more than a few Amazon devices, the network should be robust. The 900 MHz spectrum adds a lot of distance to the signals, and it’s a frequency that does a good job of penetrating obstacles like homes and trees.

Amazon believes that this network can be used by IoT device makers to improve the performance of IoT devices in a neighborhood – things like smart thermostats, appliance sensors, and smart door locks. Such devices use only a small amount of bandwidth but are reliant on the home broadband network being operational to work. Amazon’s vision with this network is that your smart door lock will still work even when your home WiFi isn’t working.

By making the network available to others, Amazon can unleash developers to create new types of wireless devices. For example, it’s always been a challenge to use outdoor sensors since WiFi signals outside of homes is weak and inconsistent. It’s not hard to imagine a whole new array of sensors enabled by the Sidewalk network. Picture a motion detector on a shed door or a leak detector on outdoor faucets. With this network, vendors can now manufacture such devices with the knowledge that most homes will be able to make the needed wireless connection.

This also holds a lot of promise for municipal and business sensors. This is a low-cost way to communicate with smart city or other sensors. This would enable, for the first time, the deployment of environment sensors anywhere within range of the Sidewalk network.

This is another interesting venture by Amazon. At least in the U.S., this is a lower-cost solution than trying to connect to IoT devices by satellite. The only cost of building this network for Amazon was adding the wireless capability to its devices – mere pennies when deployed across millions of devices. But interestingly, Amazon will also have a satellite network starting in 2025 that can fill in the gaps where the Sidewalk network can’t reach.

Amazon says that it has already made deals to test the network with companies like Netvox, OnAsset, and Primax. Now that manufacturers know this network exists and is available, this ought to open up a wide range of new IoT devices that are not reliant only on WiFi. This might finally be the network that enables the original promise of IoT of a world with sensors everywhere, keeping tabs on the environment around us.

Some Relief for WiFi?

The FCC is currently considering a proposal by Globalstar to open up a fourth and private WiFi channel. It looks like the vote is going to be close with Commissioners Rosenworcel and Pai saying they oppose the idea.

Globalstar, based in Covington, Louisiana, is a provider of satellite-based telephone systems, but has been dwarfed in that part of the industry by the much larger Iridium. Globalstar was awarded a swath of spectrum in the high 2.4 GHz bandwidth to use for its satellite phones. The Globalstar bandwidth sits next to the part of the WiFi spectrum used for Bluetooth – but there is such a small amount of satellite phone usage that interference has never been an issue.

Globalstar made a proposal to make their spectrum available for WiFi, but with the twist that the want their slice of spectrum to be private and licensed by them. This differs from the rest of the WiFi spectrum that is free and open for anybody to use. Globalstar argues that allowing some large users, such as AT&T, to use their spectrum will take a lot of the pressure off of existing WiFi.

There are places today where WiFi interference is noticeable, and it is likely to get worse. Cisco projects that the amount of data carried by WiFi will triple in the next three years – a growth rate 50% greater than data usage overall. There is expected to be a lot of demand put onto WiFi from the Internet of Things. And the cellular companies have a proposal called LTE-U that would let them dip into the WiFi spectrum for cellular data.

But as might be imagined there is a lot of opposition to the Globalstar plan. One of the major objections is that this would be a private use of the spectrum while the rest of the WiFi is available to everybody. Globalstar could license this to a handful of companies and give them an advantage over other WiFi users by giving them access to a largely empty swath of spectrum that wouldn’t have many users. Having a few companies willing to pay the price for Globalstar’s spectrum flies against the whole concept of making WiFi available to everybody.

But the primary concern about the idea is that it will cause interference with existing WiFi. Today the normal WiFi antennas used to send and receive data are not very expensive, and they routinely broadcast signals outside of the range of the narrow WiFi channels. This creates a condition called adjacent channel interference where WiFi interferes with adjacent bands of spectrum. The FCC has handled this by creating buffers around each WiFi channel that allows for the bleed-over signals.

The Globalstar spectrum sits in one of those adjacent buffer zones and critics say that heavy use of the Globalstar spectrum would directly then interfere with existing WiFi that already bleeds into the Globalstar spectrum. In general it’s never been a good idea to place two heavily used slices of spectrum next to each other without buffers, and the proposal would jam Globalstar spectrum next to existing WiFi. On the other side of the Globalstar spectrum is the part of WiFi reserved for Bluetooth, and again use of the spectrum would eliminate any buffer.

The opponents to the idea have been very vocal. They don’t think the FCC should allow for the risk that Globalstar will create a clear channel for a few carriers while interfering with everybody else trying to use WiFI. The industry as a whole says this is an overall losing idea.

The issue has been in front of the FCC for a few years and looks like it will come to a vote soon. Chairman Wheeler is for the Globalstar plan with two other Commissioners already against it. It will be up to the final two commissioners to decide if this is a go or not.

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