Personal Area Networks (cont.)

The State Of The Technology

A PAN prototype has been developed to demonstrate the digital exchange of data through a human body using battery-powered low-cost electronic circuitry. The detector is a current amp (gain = 106) followed by an analog bipolar chopper controlled by a digital microcontroller. The detector synchronously integrates the tiny received displacement current (e.g., 50 picoamperes, 330 KHz) into a voltage that can be measured by a slow, low-resolution analog-to-digital converter (50 KHz, 8 bits) provided by the microcontroller. The PAN transceiver uses five "off-the-shelf" components costing less than $10 in large volumes. Ultimately the analog components and microcontroller can be combined into a single CMOS (complementary metal-oxide semiconductor) integrated circuit to produce a low-cost integrated PAN transceiver.

Issues and Concerns

The biggest issue is security. With the present generation PAN systems, the transfer of data across devices has become quite simple. This increases the risk of transferring data accidentally if you bump into somebody. It is convenient to transfer my ATM code into the teller machine, but the same should not happen if someone touches me while I am doing so. So, a lot of work on encryption techniques must be done.

Signal strength and interference play a critical role in deciding the location of the device. The first generation of systems have to be situated at the feet because the signal is strongest there because of the close proximity to the ground. But feet may not be the logical place for credit cards for example. So, a 2nd generation of PAN transceivers need be built that work effectively from wallets and pockets. Also the body must be isolated from ground for the system to work properly. In an experiment it was demonstrated that the signal strength falls considerably if one stands bare footed.

The next important development that is required is that of monolithic devices. To make carrying of PAN devices feasible, all things like battery, microprocessor and copperplates must be designed as a single compact unit.

Also, to gain wide acceptance, the technology must get out fast from the prototyping stage and cross-industry effort is required to dwell on various higher level issues also (unlike Bluetooth, PAN is an industry initiative (IBM) ). Lack of proper application development interfaces, for example, could hinder the acceptance of the technology.

Applications of the Technology

According to Tom Zimmerman, "One of the great potential commercial applications for this is to replace the half-dozen pieces of plastic you have in your wallet, which are all doing the same thing, identifying you. But they all do it in a slightly different way. Either you wait on a line and hand a card to a teller, who types a number into a computer, or you swipe a card through a reader, or, with a calling card, you punch in a dozen digits, then dial your long distance number, and if you make a mistake you have to do it all again. So, it's inconvenient and insecure".

A lot of other interesting applications have been proposed which signify the potential of the technology. These include:

1. Next time you need to exchange business cards just shake hands. The electronic card is transferred automatically from the your card device via your body, transmitted to the other person via his hand in contact with yours to his card device and vice versa. At a recent show, Zimmerman enlisted several CEOs from some of the world's largest corporations to hold hands, forming one of the highest-priced data networks in history. Information on the card of the CEO on one end of the network flowed through the intervening bodies and was detected by the card at the far end.

2. You enter your local supermarket and your preferences of brands is automatically transferred to the supermarket database from a PAN device in your foot to a PAN receiver in the supermarket floor (ofcourse with your permission, and the supermarket may offer some discount to people who are willing to pass on the information !)

3. You could transfer information between all sorts of electronic devices: cellular phones, pagers, personal digital assistants (PDAs) and smart cards. For instance, when someone sends you a telephone number on your pager, you could transfer that number automatically to your cellular phone.

4. No problem of synching the address books of you PDAs, mobile phone etc. This can be done seamlessly over your PAN.

5. If you want to make a long distance call using your pre-paid card. You don't have to key in your PIN first. The phone can sense your PIN as soon as you touch the key pad. The PIN is transferred securely from your pre-paid card in your pocket to the phone by a simple touch

6. Homework assignments, grades, shopping lists, errands, and reminders could be automatically exchanged among family members at the dinner table.

7. In case of medical emergencies the doctors can immediately access all your medical information at the touch of a finger.

8. IBM researcher David Thompson envisions a prosthetic memory system that could be hidden in one's clothing - a miniature camera to record those new faces, a microphone hooked to a speech recognition system that would record and transcribe conversations, a visual display built into a wrist watch or displayed heads-up fashion on a pair of eyeglasses, and a very high-density hard disk.
9. When you reach your house in the evening the door could open immediately when you touch the door knob. An identification code could flow from your body to the door knob and on authentication it could open.

Using The Body to Transfer Power

Recently it was demonstrated that using the body, we cannot only transfer data between devices but power as well [4]. This observation can have great implications. A device can be put into the shoe which can convert the mechanical energy generated while walking into electrical power which can be transmitted through body to some device which can use this to power it's operations. This means no power issues!! A shoe is something that we always take with us where ever we go and hence can be an ideal and convenient place for keeping such devices.

How Is This Possible?

Each datum of information received by our body has a low but nonzero energy, the excess energy accumulated in receiving and demodulating these bits may itself be used to power circuitry. If a circuit requires only a small amount of current to run, then it is possible by careful design to obtain that current from the data signals coming into the circuit.

It has been shown that under reasonable conditions, an available power of 200mW at 1.0 MHz applied at one hand leads to the recovery of around 20mW of rectified, filtered DC power at one foot.

Expanding The Horizons Of PANS

Just as networking between devices open up a wide spectrum of applications, networking of networks can expand the horizons considerably. Whereas a PAN is limited to the communication between devices you are carrying or you are in contact with, using technologies like Bluetooth your body network can connect to the outside world. Your watch or mobile phone may be bluetooth enabled and can act as the interface of your body network to the outside world. Consider the same example of you getting a page message and the message sent over to the watch using PAN. If your watch is Bluetooth-enabled and you are sitting in your office in front of your desktop computer, your watch could send this message over to your PC instantly and you could see the message in a pop-up window on your monitor screen. If you don't have a PDA in your waist pocket the watch could talk to your PC or the Laptop using Bluetooth and upload the phone number to your mobile using your body network (PAN). Bluetooth is a short range radio technology which enables instant formation of networks between devices within 10m of range. Refer to http://www.bluetooth.com for more details.

It must be observed that the scope and effectiveness of PAN, Bluetooth, and IrDA depends on the context and the application. Where high speed inter-device communication is required, PAN can't match the speeds provided by Bluetooth or IrDA. But again, the power levels required in PAN make it much better for the kind of applications we have been talking about. So, we should see Bluetooth making inroads into applications like connecting various devices inside your homes, offices etc. It is most suitable for wireless headphones for mobiles, digital cameras, notebook computers, PDAs etc. You can already see many such Bluetooth-enabled products in the market. IrDA is a point-to-point, narrow angle (30° cone), ad-hoc data transmission standard designed to operate over a distance of 0 to 1 meter and at speeds of 9600 bps to 16 Mbps using infrared. Infrared devices would be seen in cordless keyboards, TV remote controls, printers, watches (where you need to occasionally synchronize it with your PC, etc.), and serial PC adapters. Many of the areas and applications overlap and we should see more than one competing technology. The result is that PCs and Notebooks should provide more than one wireless interface.

Next: Conclusion