Near-field communications (NFC), which traces its heritage to radio-frequency identification (RFID), has lately been promoted as a way to enable mobile phones and other portable devices to serve as electronic wallets. Early examples of the technology, operating on the 13.56 MHz ISO/IEC 18000-3 air interface with transfer rates ranging from 106 kbps to 848 kbps, exist today in cellular handsets such as Google’s Nexus S, developed by Samsung and leveraging a NFC transceiver from NXP Semiconductors. But startup Naratte believes that its ultrasonic “Zoosh” technology can bring the promise of NFC more rapidly to fruition, via a proprietary implementation leveraging an alternative type of spectrum.
In contrast to RF-based NFC technology, Naratte harnesses the microphone and speakers in existing smartphones and feature phones to enable wireless transactions using an audio frequency range just above the 20 kHz upper end of human hearing. Cellular handset owners (with the possible exception of audiophiles) therefore shouldn’t be bothered by Zoosh transmissions, although their dogs might not be pleased. Naratte’s secret sauce is the digital signal processing code that runs on mobile devices’ application processors, enabling secure transactions between two handsets, or between a handset and a point-of-sale terminal.
Zoosh technology (Figure 1) is based on a proprietary modulation scheme used to encode data, today enabling transmission at speeds of approximately 300 bps. Although this is a very slow data rate, Naratte claims that it’s sufficient to allow Zoosh-enabled devices to complete a transaction in less than one second. And Naratte expects Zoosh to work on a large number of existing phones and other devices, such as PCs, PDAs, portable multimedia players, and tablets—with no hardware modifications required.
Figure 1. Zoosh leverages ultrasonic spectrum just above the human audible range to send encoded 300 bps transmissions using the microphones and speakers in existing mobile electronics devices.
The mobile-device industry envisions 13.56 MHz radio frequency NFC as a replacement for the cash and credit cards traditionally used by consumers to pay for goods and services. Mobile service operators, financial institutions, mobile device makers, and chip manufacturers are all working to standardize RF-based NFC schemes that allow two devices in close proximity to securely interact. And NFC trials are underway in various facilities around the globe. But today few smartphones have NFC chips, and the retail infrastructure needed to support NFC is nascent.
Naratte believes that 2015 is the earliest that broad RF NFC deployment will occur, given that it will take at least two years (and likely longer) for phones with NFC ICs to become prevalent. That delay accounts both for the design cycle of new phones and for the consumer equipment-upgrade cycle that’s defined by multi-year service contracts. And until a critical mass of mobile devices support NFC, wide deployment of NFC infrastructure in the merchant space won’t follow.
In contrast, Zoosh technology is ready for immediate deployment, according to Naratte. The company asserts that Zoosh will work on any existing phone that includes an MP3 playback function. If the phone can play music, the company says that it can also transmit the inaudible Zoosh signal—as long as its speaker is also up to the tweeter-tailored task.
For a phone to receive and decode a Zoosh transmission, on the other hand, Naratte says that it needs to be capable of speech recognition. More precisely, the microphone signal chain in the phone needs to be capable of 44.1 kHz or faster sample rates, along with being sufficiently spectrum-adept to detect signals above 20 kHz. The company says that it has exhaustively verified Zoosh operability on popular smartphones such as iPhones and Android-based handsets. The company has also successfully tested the technology on a smaller suite of about 20 feature phones.
Naratte has purposefully engineered a relative short range for Zoosh transmissions, intending that two devices be within 6 inches of one another in order to complete a transaction. The scant range is security-friendly, making it difficult for eavesdroppers to intercept a transmission. The short span also helps ensure that a given Zoosh transaction doesn’t interfere with other nearby Zoosh-enabled devices. Naratte suggests that the range could be substantially extended in other applications. The company reports, for example, that it has successfully tested iPhones at ranges of 5 to 6 feet, due to the high-quality speaker, microphone and audio signal chain in these particular devices.
Naratte envisions a number of usage scenarios, some of which might not even require explicit Zoosh support within a phone. For example, a retailer could send email or text messages to a consumer, along with a MP3 file attachment that combines both an audible promotional message—say an audio offer for a discount on a cup of coffee—and a Zoosh-encoded transmission payload comprising the retailer’s discount coupon. The consumer could play the MP3 at the point of sale to redeem the coupon. The retailer would use its own IT infrastructure to monitor Zoosh coupon access, placing transaction-count, expiration date, or other constraints on its use as desired.
Some feature phones may be capable of running Zoosh software only for outbound transmissions. In such a case, the feature phone owner could still load electronic currency on the device and use it for transactions with Zoosh-supported point-of-sale terminals. From a security perspective, Naratte asserts that even one-way transmissions are protected against replay attacks via the use of unique and perishable transaction IDs, although the retailer would again be responsible for implementing security via its IT system.
Phones that can support both send and receive capabilities open up even more implementation possibilities. In a point-of-sale application, a bidirectional transmission could allow an additional level of security. And Naratte is working on using Zoosh to instantly pair two Bluetooth devices—another application envisioned by the RF NFC industry.
Naratte recently announced its first partner, SparkBase, which is launching a Zoosh trial in a retail loyalty application. A SparkBase-developed and freely downloadable application will allow iPhone and Android phone users to find merchants that participate in the new SparkBase Paycloud program, join merchant loyalty programs, and receive Zoosh coupons, promotions, and rewards.
According to SparkBase, merchants can get started with the Zoosh-based Paycloud program for less than $100, including the Zoosh sensor and the software for a point-of-sale terminal. Naratte expects the SparkBase trial to be in more than 1,000 stores by next month.
Naratte is certainly taking a contrarian path, considering how much industry attention is focused on RF-based NFC technology. But the start-up’s clever use of digital signal processing algorithms to implement audio-based NFC has the compelling advantage of not requiring new hardware. This means that it can be deployed very inexpensively, and can be added to existing mobile devices.
It’s important to realize that Zoosh is by no means the first technology using sound to make mobile contactless transactions. Sound Based Technologies (SBT) have been defining mobile contactless transactions in many countries while NFC has been struggling to take off. The leading SBT, Near Sound Data Transfer (NSDT™), is enabling mobile-based financial services in over 30 emerging markets including Namibia with Mobipay, Nicaragua with MPeso, Ivory Coast with Orange Money, and others. NSDT is also being used for physical access control, web authentication, and a range of other contactless mobile-transaction applications in the US and Europe. Technologies like NSDT and Zoosh prove that contactless transactions are fortunately not exclusive to NFC devices. There are secure, fast, and simple alternatives to NFC that don’t require handset modification and, in the case of NSDT, don’t even require you to download an application or have a smart phone. E-mail me at email@example.com if you would like more information on Near Sound Data Transfer or a demo.