Radio Spectrum The Achilles’ Heel of Wireless Computing Fred L. Strickland COMP 7970 Persuasive Computing Fall 2002 Directed by Dr Richard Chapman Auburn University, Auburn Alabama

Abstract Wireless devices are everywhere. Communicate while moving Work outside of the desk Are there any draw backs?

Outline What radio bands may be used? What are the behaviors of these bands? What are in those bands? What problems exist today? What problems may happen tomorrow? Is there an answer?

What radio bands may be used? Wireless devices are really radios.

The License Free Radio Bands - Industry Scientific and Medical (ISM) 6,765-7,000 kHz (HF) 13,410-13,570 kHz (HF) 26,950-27,410 kHz (HF) MHz (VHF) MHz (UHF) GHz (UHF) GHz (SHF) GHz (SHF) GHz (EHF) GHz (EHF) GHz (EHF)

- Unlicensed National Informational Infrastructure (UNII) GHz (SHF) GHz (SHF) GHz (SHF)

- Unallocated bands Below 9 kHz Above 400 GHz (EHF)

So what does this all mean? –

What are these bands and their behaviors? ELF(Extremely Low Frequency): 30 to 300 Hz 300 to 3,000 Hz VLF (Very Low frequency): 3,000 Hz or 3 kHz to 30 kHz) LF (Low Frequency): 30 to 300 kHz

Behavior, continue MF (Medium Frequency) 300 to 3,000 kHz HF (High Frequency) 3,000 kHz to 30,000 kHz Or 3 to 30 MHz

Behavior, continue VHF (Very High Frequency) 30 to 300 MHz FM Broadcast band (88 to 108) FM Broadcast band Air Traffic Control (108 to 138) Television (begins here) UHF (Ultra High Frequency) 300 to 3,000 MHz Same as above, plus radar.

Behavior, continue SHF (Super High Frequency) 3,000 to 30,000 MHz OR 3 to 30 GHz EHF (Extremely High Frequency) 30 to 300 GHz

What activities are in those bands?

What problems exist today? In general What will the FCC do? Between a licensed user and a non-licensed user:  The non-licensed user must  Reduce power  Change operations  Shut down Between two or more non-licensed users  For the most part, the FCC does not oversee the conflict.

Current Problems, continue Do systems co-exist peacefully?

Current Problems, continue Radars and the Dedicated Short-Range Communication (DSRC) System The DSRC could live near a radar with 1 meter separation and the right combination of frequency usage and antennas. If the DSRC was on the same frequency with a regular antenna, then it would need 7.1 kilometers of separation ! Guess what band these systems operate in? Guess what is the placement of these systems?

Current Problems, continue Cordless telephones Operate in 900 MHz 2.4 GHz 5.8 GHz

Current Problems, continue Cordless telephones do cause interference to other wireless devices: To baby monitors To headphones To audio products To video products Cordless telephones do receive interference from other devices, such as Microwave ovens Wireless computer networks And other devices operating in the 2.4 GHz band

Current Problems, continue: In the context of wireless computer users, how well do these wireless computer devices work?  Bandwidth or data rate  Transmission range  Still need wires to somewhere  Limited support to wireless users  Performance  Security

Current Problems, continue Bandwidth or data rate IEEE a 6 to 54 Megabits per second in the 5 GHz band IEEE b 2 to 11 Megabits per second in the 2.8 GHz band

Current Problems, continue Transmission range IEEE a 15 feet for 54 Megabits per second Lower the rate and the distance increases IEEE b Roughly 300 feet Thick concrete walls will cut down the range even more or stop it completely.

Current Problems, continue The cord cannot be completed cut. Access points are needed. Wires must run from each access point device to a network hub, bridge, or router. Running wires has it challenges too.

Roughly, how many access points does Dartmouth College use to cover the campus?

Over 500 access points!

Current Problems, continue How many users? IEEE a can support 8 channels IEEE b can support 3 channels Hard to tell How many users can a single access point support? How many access points can you have in a large lecture hall?

Current Problems, continue Another weakness is the area of performance. Wireless connections will never approach the reliability and performance of wired networks. Wireless connections are subject to noise, weak signals, and other communications problems. The current best data rate is below the best telephone modem rate of 56 kilobits per second.

Current Problems, continue The point is security. Not on par with wired security systems. Some system administrators turn it off. Dartmouth College did this so that any one on campus could access the network. Once a signal is in the air, anyone can listen to it.

What problems may happen tomorrow? The demands for more radio spectrum keeps growing. A 1995 study* determined that 204 MHz of bandwidth (radio spectrum) is needed for new... Cellular users Personal communications services Mobile satellites Intelligent transportation system sectors * NTIA Report : A Technological Rational to Use Higher Wireless Frequencies, February 1998

Future Problems, continued Some want to increase the 5 GHz band. Some want GHz. This band is important to the Department of Defense. High power radars and low power wireless computer devices cannot live together

Future Problems, continued As more devices appear in an area, then the overall throughput will decrease. IEEE a and IEEE b are still evolving Some companies (Intel and Microsoft) are planning to sell products in 2003 with the current evolving standard in wireless products. Open wireless networks can be hacked. Any illegal activities could be charged to the network owner.

Is there an answer? Try doing something else. Talk face to face instead of using Instant Messenger. Use wires instead of going wireless.

Answer, continued Think about your needs Do you really need a wireless connection from the local cemetery? (Dartmouth College thinks so, but that seems to be a bit extreme.)

Answer, continued There are things that companies should be doing. Do not oversell the benefits of being wireless. Try other ISM radio bands. Fix the receiver problems.

What now? The end or the beginning. This presentation was To touch upon the radio spectrum side of wireless computing. To make you aware of some of the hidden problems. To ask you to change your lifestyle a bit. To join your voice with others to ask for companies to fix their equipment.

Questions? Comments? Feedback? Your turn.

Added material Satellite radio is in to 2345 MHz Global Positioning Satellites are in 1575 MHz The satellite radio groups want more frequencies around the GPS radio bands.