Researchers may have solved a key problem underlying the emerging “Internet of Things” (IoT): How can these “Things” talk back to their networks? The answer could be by reflecting the ambient signals from conventional Wi-Fi routers.

Forecasts about the Internet of Things—the idea that cars, appliances, clothes, and other devices will all soon be wired in to the ‘Net—mean little if IoT devices still require batteries or plugged-in power supplies to operate. Smartphones and laptops fully occupy many households’ power outlets, having already laid claim with their charging stations and the requisite tangled scads of plugs, cord,s and connectors. Charging or changing batteries on many more devices around the home or workplace would, for most consumers, present too much bother for too little return.

So if the IoT is to be adopted in everyday consumer applications, much of the data transfer will need to go on in the background and without the help of batteries. IEEE Spectrum has previously covered advances in batteryless computing and even batteryless cryptographic security. Limited computing in batteryless devices has generally been possible using harvested radio-frequency power from ambient TV, radio, cellphone, and Wi-Fi signals—and in the case of RFID chips, from the occasional jolt supplied by a nearby RFID reader.

However, as a video describing the new research explains, the operating power batteryless devices require for wireless communications is two or three orders of magnitude higher than they can passively harvest. As a result, small batteryless IoT devices (such as some wearables or sensor motes around a house) have to date behaved less like full-fledged members of an active local network and more like children in 19th century novels, quietly brooding away and speaking only when directly spoken to.

This month, though, Joshua Smith and colleagues in the departments of electrical engineering and computer science at the University of Washington in Seattle reported that they have prototyped a different approach to batteryless device connectivity. Instead of generating their own signals, their batteryless WiFi Backscatter chips transmit their bits by either reflecting or not reflecting a Wi-Fi router’s signals.

“You might think, how could this possibly work when you have a low-power device making such a tiny change in the wireless signal?” Smith said in a statement accompanying the research. “But the point is, if you’re looking for specific patterns, you can find it among all the other Wi-Fi reflections in an environment,” (The group’s will present the research at the SIGCOMM 2014 annual meeting in Chicago which will take place from 17 to 22 August.)

That said, however, the essential idea behind the scheme—making batteryless devices reflectors of existing signals rather than transmitters of their own unique signals—may at first blush seem insufficient for scaling up to even a single household where possibly hundreds of batteryless network nodes could exist.

The paper offers some initial thoughts about that. First, it says, Internet communications is typically “bursty.” So perhaps multiple backscatter nodes seeking to communicate with the network can just wait their turn until the channel’s clear.

Second, most tiny, batteryless devices don’t have much data to transmit even when they do have something to say. So a little bit of connectivity in this context could still go a long way.

“Establishing a communication link between WiFi Backscatter tags with existing Wi-Fi devices, albeit at a low rate, is [still] beneficial for a large class of Internet-of-Things applications,” the researchers say.

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The Spectacular Collapse of CryptoKitties, the First Big Blockchain Game

A cautionary tale of NFTs, Ethereum, and cryptocurrency security

8 min read
Mountains and cresting waves made of cartoon cats and large green coins.
Frank Stockton

On 4 September 2018, someone known only as Rabono bought an angry cartoon cat named Dragon for 600 ether—an amount of Ethereum cryptocurrency worth about US $170,000 at the time, or $745,000 at the cryptocurrency’s value in July 2022.

It was by far the highest transaction yet for a nonfungible token (NFT), the then-new concept of a unique digital asset. And it was a headline-grabbing opportunity for CryptoKitties, the world’s first blockchain gaming hit. But the sky-high transaction obscured a more difficult truth: CryptoKitties was dying, and it had been for some time.

The launch of CryptoKitties drove up the value of Ether and the number of transactions on its blockchain. Even as the game's transaction volume plummeted, the number of Ethereum transactions continued to rise, possibly because of the arrival of multiple copycat NFT games.

That perhaps unrealistic wish becomes impossible once the downward spiral begins. Players, feeling no other attachment to the game than growing an investment, quickly flee and don’t return.

Whereas some blockchain games have seemingly ignored the perils of CryptoKitties’ quick growth and long decline, others have learned from the strain it placed on the Ethereum network. Most blockchain games now use a sidechain, a blockchain that exists independently but connects to another, more prominent “parent” blockchain. The chains are connected by a bridge that facilitates the transfer of tokens between each chain. This prevents a rise in fees on the primary blockchain, as all game activity occurs on the sidechain.

Yet even this new strategy comes with problems, because sidechains are proving to be less secure than the parent blockchain. An attack on Ronin, the sidechain used by Axie Infinity, let the hackers get away with the equivalent of $600 million. Polygon, another sidechain often used by blockchain games, had to patch an exploit that put $850 million at risk and pay a bug bounty of $2 million to the hacker who spotted the issue. Players who own NFTs on a sidechain are now warily eyeing its security.

Remember Dragon

The cryptocurrency wallet that owns the near million dollar kitten Dragon now holds barely 30 dollars’ worth of ether and hasn’t traded in NFTs for years. Wallets are anonymous, so it’s possible the person behind the wallet moved on to another. Still, it’s hard not to see the wallet’s inactivity as a sign that, for Rabono, the fun didn’t last.

Whether blockchain games and NFTs shoot to the moon or fall to zero, Bladon remains proud of what CryptoKitties accomplished and hopeful it nudged the blockchain industry in a more approachable direction.

“Before CryptoKitties, if you were to say ‘blockchain,’ everyone would have assumed you’re talking about cryptocurrency,” says Bladon. “What I’m proudest of is that it was something genuinely novel. There was real technical innovation, and seemingly, a real culture impact.”

This article was corrected on 11 August 2022 to give the correct date of Bryce Bladon's departure from Dapper Labs.

This article appears in the September 2022 print issue as “The Spectacular Collapse of CryptoKitties.”

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