Seamless connectivity between people, objects, and events—such a climate once seemed so daunting. Not any more, thanks to rapid-fire advances made in sensor, computing, and communications technologies, let alone the pervasive use of the Internet. Entirely new applications will embed computing power and wireless communications in our daily lives.
Advances in both telecom and the Internet will converge to deliver ubiquitous wireless sensor networks and pervasive computing (Fig. 1). Professor Dipankar Raychaudhuri, director of the Wireless Information Network Laboratory (WINLAB) at Rutgers University, sees five key changes:
- In frictionless capitalism, consumers can find goods and services by consulting their PDAs as they walk through town. They also can go into stores and purchase these items without the need for any cashiers.
- Smart transportation systems can route vehicles around traffic jams in real time. They also can provide collision-avoidance feedback with augmented reality displays. On top of that, they can guide people to their parked vehicles in a crowded garage or parking lot.
- Airport logistics and security systems can enable passengers to board their planes, find their lost bags (via RFID tags), and be screened for unusual patterns, all with minimal interruption.
- Smart homes will play a key role in assisted living for the disabled and elderly (Fig. 2).
- Workers in smart offices will be able to quickly and accurately search for physical objects, documents, and books. They will also be able to maintain "lifelogs" of stored events by location and/or time and date.
The cell phone will play an important role in the real-world application of many of these scenarios. Customers could use their phone, for instance, to pay for food at the grocery store, eliminating the need to carry cash or a credit card. Motorola's M-Wallet cell phone is an indicator of how these capabilities will be incorporated into the designs of third-generation (3G) handheld devices. With the M-Wallet, users can pay bills, conduct money transfers, and complete point-of-sale (POS) purchases.
The MIMOSA (MIcrosystems platform for MObile Services and Applications) consortium has set its sights on an open technology platform for ambient intelligence centered around mobile-phone technology. This organization, which comprises 16 member partners in eight European countries, is funded by the European Union's Sixth Framework for Research and Technological Development (Fig. 3).
MULTIMODE LOW-POWER SENSORS IN DEMAND
There's a lot of demand for sensors that can measure more than one parameter while dissipating a lot less power. "Sensors, in general, do not have enough output power and range to make it [survive the transition] into a wireless world," says Rutgers University's Raychaudhuri.
One proposal uses sensors in a pulsed output mode to minimize power dissipation. One thing is clear, though. For untethered electronics, a low-cost, reliable alternative to the battery has yet to be found. Until then we must rely on improvements in battery technology, which have their limits (see "The Promise Of Harvested Energy," p. 55).
Intelligent micro electromechanical-system (MEMS) sensors are being developed to address these problems. In a joint effort, the University of Florida and Freescale Semiconductor foresee the possibility of a very low-cost MEMS motion sensor that dissipates a mere 1 mW, giving it the potential to operate continuously for up to one year. It's so sensitive, it can sense sounds as well as motion. Compatible with a standard IC process, the device can be planted inside helmets and clothing to monitor the body movements of athletes and home-care patients.
The Rutgers University WINLAB is working on a multimodal wireless sensor (MUSE) multichip module that includes a sensor, the RF communications circuitry, a modem, a CPU, and supporting circuits (Fig. 4). Integrated with low-power transceiver designs, applications are initially targeted at medical heat-monitoring applications. Ultimately, it will be used in a wide range of other applications that call for a sensor, including heat, light, motion, and water-flow.
The tunable MUSE device consists of zinc-oxide materials, and it can be programmed to operate in dual modes (acoustic and ultraviolet optic). It can also be reset to increase sensitivity for liquid and gas sensing. First-generation implementations will be in system-on-package (SiP) and system-on-a-chip (SoC) configurations. A single-chip prototype is slated to debut sometime this year.
Minimizing sensor power-dissipation levels and maximizing output levels (and thus transceiver range) are, of course, two key goals for designers. However, efforts also are under way to minimize transmitted sensor data loss and maximize sensor output information content via smart MEMS sensors.
With the two latter goals in mind, the National Center for Supercomputing Applications at the University of Illinois Urbana-Champaign developed a thermal infrared (IR) wireless MEMS sensor that calibrates cameras. The work was jointly performed with Crossbow Technology, using its MICA sensor hardware, and Indigo Systems Inc. with its thermal IR cameras.
Nokia's Bluetooth low-end extension (BTLEE) radio concept seeks to improve Bluetooth transmissions and lower costs. It complements Bluetooth by allowing small devices (those limited in battery power, size, weight, and cost) to have wireless connections to mobile terminals without adding yet another radio to those mobile terminals. Nokia developed a BTLEE radio system to demonstrate the concept's feasibility and expects to push out products next year.
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