Tuesday, April 22, 2008

Wireless Glossary

1X or 1XRTT: A high speed data protocol that is used with CDMA phones and devices for wireless internet.

2G: The most common type of phone in North America today. 2G phones deliver both voice and data transmissions, but primarily focus on voice communications. Data connections using the wireless phone are similar to dial-up connections using a older modem and speeds are quite slow. Okay for simple text messages (SMS) and email, but not much else.

2.5G: An intermediate bridging standard between 2G and 3G phones. 2G phones are purely digital and can transmit wireless data at about the same rate as a dial-up connection with a fast modem. Good for email and simple web browsing.

3G: A third-generation high-speed mobile phone that will eventually provide data at rates similar to cable or ADSL. At present, very limited availability and data transfer speeds are limited to about 144 Kbps.

3G: 4G is the broadband mobile communications that will supersede 3G. Standards bodies and carriers have not yet concretely defined or agreed upon what exactly 4G will be. However, it is expected that end-to-end IP and high-quality streaming video will be among 4G's distinguishing features. Fourth generation networks are likely to use a combination of Wi-Fi & Wi-Max.

802.11: A group of wireless specifications developed by the IEEE. It details a wireless interface between devices to manage packet traffic (to avoid collisions, etc.) Some common specifications and their distinctive attributes include the following:

802.11a -- Operates in the 5-GHz frequency range (5.125 to 5.85 GHz) with a maximum 54Mbit/sec. signaling rate. The 5-GHz frequency band isn't as crowded as the 2.4-GHz frequency because it offers significantly more radio channels than the 802.11b and is used by fewer applications. It has a shorter range than 802.11g, is actually newer than 802.11b and isn't compatible with 802.11b.

802.11b -- Operates in the 2.4-GHz Industrial, Scientific and Measurement (ISM) band (2.4 to 2.4835 GHz) and provides signaling rates of up to 11Mbit/sec. This is a very commonly used frequency. Microwave ovens, cordless phones, medical and scientific equipment, as well as Bluetooth devices, all work within the 2.4-GHz ISM band.

802.11e -- Due to be ratified by the IEEE in June, the 802.11e quality-of-service specification is designed to guarantee the quality of voice and video traffic. It will be particularly important for companies interested in using Wi-Fi phones.

802.11g -- Similar to 802.11b, but this standard supports signaling rates of up to 54Mbit/sec. It also operates in the heavily used 2.4-GHz ISM band but uses a different radio technology to boost overall throughput. Compatible with older 802.11b.

802.11i -- Also called Wi-Fi Protected Access 2 (WPA 2), 802.11i was ratified in June 2004. WPA 2 supports the 128-bit Advanced Encryption Standard, along with 802.1x authentication and key management features.

802.11k -- The 802.11k Radio Resource Management standard will provide measurement information for access points and switches to make wireless LANs run more efficiently. It may, for example, better distribute traffic loads across access points or allow dynamic adjustments of transmission power to minimize interference.

802.11n -- The Standard for Enhancements for Higher Throughput is designed to raise effective WLAN throughput to 100Mbit/sec. But the group handling this task is still in the very early stages of its work.

Access point: A WLAN transceiver or "base station" that can connect a network to one or many wireless devices. APs can also bridge to one another.

Ad hoc mode: A wireless network framework in which devices can communicate directly with one another without using an AP or a connection to a regular network. Contrasts with an infrastructure network, in which all devices communicate through an AP.

Airtime: Actual time spent talking on your cellular telephone. In general most cellular phone companies charge you from the time you hit the SEND button until you hit the END button (i.e., you pay to listen to a ringing signal, but only if someone answers). GSM phone companies generally charge actual talk time and not time listening to ringing signals. You are not charged for listening to busy signals or if your call is not answered.

AMPS: Advanced Mobile Phone Service; commonly known as analog cellular that uses the 800 MHz spectrum. AMPS service has been available in North America since the mid 80's and it is also available in Central and South America. AMPS is quickly being phased out as more energy is needed to make and monitor for calls from a handset plus providers rather use the newer digital technologies that allow them to squeeze several callers onto one channel.

Base Station: A transmission and reception station for handling cellular traffic. Usually consists of one or more receive/transmit antenna, microwave dish, and electronic circuitry. Also referred to as a cell site, since it holds one or more tx/rx cells. Base stations are constructed and placed on high buildings, hydro towers, monopoles, or other structures with a good elevation above the area to be covered. Several base stations within an area form a wireless network. On average, 800 MHz sites are spaced about 10-12 km (6-8 mi) apart and 1900 MHz sites are spaced about 3-4 km (2-2.5 mi) apart. In high network traffic areas base stations are placed much closer together. Base stations may also be placed closer together to deal with interference from adjacent buildings and other geographic irregularities. Even a Simpsons episode featured a cellular base station above their house. Mind you, real base stations don't look like this!

BlueTooth: Bluetooth is a specification for providing links between mobile computers, mobile phones and other portable handheld devices, and connectivity to the Internet. It enables users to connect a wide range of computing and telecommunications devices easily and simply without the need to buy, carry, or connect cables.

CDMA: Code Division Multiple Access. One of the newer digital technologies in use in Canada, the US, Australia, and some southeastern Asian countries (e.g. Hong Kong and South Korea). CDMA differs from GSM and TDMA by its use of spread spectrum techniques for transmitting voice or data over the air. Rather than dividing the radio frequency spectrum into separate user channels by frequency slices or time slots, spread spectrum technology separates users by assigning them digital codes within the same broad spectrum. Advantages of CDMA include higher user capacity and immunity from interference by other signals. Available in either 800 or 1900 MHz frequencies.

CDPD: Cellular Digital Packet Data technology is used by telecommunications carriers to transfer data to users via unused analog cellular networks. If one part of the network -- a specific geographic area or "cell" -- is overused, CDPD can automatically reallocate network resources to handle extra traffic.

Cell: The basic geographic unit of a cellular system and the basis for the generic industry term "cellular." A city is divided into small "cells", each of which is equipped with a low-powered radio transmitter/receiver or base station. The cells can vary in size depending on terrain and capacity demands. By controlling the transmission power and the radio frequencies assigned from one cell to another, a computer at the MTSO monitors the movement and transfers or hands off the phone call to another cell and another radio frequency as needed.

Codec: Short for "compressor/decompressor"; refers to the hardware in a cell phone and in the cell network that compresses digitized voice prior to transmission AND takes received compressed voice and decompresses it prior to passing it to either a cell phone speaker or into a wireline system. Codec allows the cell network to essentially pass a lot of data in compressed form to permit additional users on the system and to save bandwidth. The idea behind codec is that human voices are highly lossy and a significant amount of the conversation can be removed since human ears can fill in the removed gaps at the other end. Each technology has different codec algorithms -- for CDMA there is 13K and 8K.

Control Channel: A channel used for transmission of digital control information from a base station to a cellular phone (forward control channel) or from a cellular phone to a base station (reverse control channel).

CTIA: The Cellular Telecommunications & Internet Association is the international organization that aims to represent all elements of wireless communication -- cellular, personal communications services, enhanced specialized mobile radio and mobile satellite services -- and serve the interests of service providers, manufacturers and others.

Dual Band: Dual band phones are capable of using two different frequencies of the same technologies. For example a TDMA or CDMA phone that can use either the 800 or 1900 MHz band. There are also Triple Band phones in the GSM market that support 900, 1800, and 1900 MHz. Dual band phones allow you to access different frequencies in the same or different geographic regions, essentially giving your phone a wider coverage area.

Dual Mode: Dual mode phones that support more that one technology. For example a 800 MHz CDMA phone that also supports 800 MHz AMPS. You can also have phones that support dual band/dual mode such as the Nokia 6185 which is 800, 1900 MHz CDMA and 800 MHz AMPS. Dual mode phones allow you to access different technologies in the same or different geographic regions, essentially giving your phone a wider coverage area.

ESN: Each cellular phone is assigned an unique ESN or Electronic Serial Number, which is automatically transmitted to the cellular base station every time a call is placed. The MTSO validates the ESN with each call. Cloned cellular phones transmit a stolen ESN and charges are made to the real cellular phone account.

Frequency reuse: The ability to use the same frequencies repeatedly across a cellular system, made possible by the basic design approach for cellular. Since each cell is designed to use radio frequencies only within its boundaries, the same frequencies can be reused in other cells not far away with little potential for interference. The reuse of frequencies is what enables a cellular system to handle a huge number of calls with a limited number of channels.

GPS: The Global Positioning System is a "constellation" of 24 satellites that orbit the Earth at a height of 10,900 miles, making it possible for people using ground receivers to determine their geographic location within 10 to 100 meters. The satellites use simple mathematical calculations to broadcast information that is translated as longitude, latitude and altitude by Earth-based receivers.

GPRS: General Packet Radio Service technology runs at speeds up to 115Kbit/sec., compared with the 9.6Kbit/sec. of older GSM systems. It enables high-speed wireless Internet and other communications such as e-mail, games and applications. It supports a wide range of bandwidths and is an efficient use of limited bandwidth. It's particularly suited for sending and receiving small amounts of data, such as e-mail and Web browsing, as well as large volumes of data.

GSM: Global System for Mobile communications. The most common digital cellular system in the world. GSM is used all over Europe, plus many countries in the Middle East, Asia, Africa, South America, Australia, and North America. GSM's air interface is based on narrowband TDMA technology, where available frequency bands are divided into time slots, with each user having access to one time slot at regular intervals. Narrow band TDMA allows eight simultaneous communications on a single radio multiplexor and is designed to support 16 half-rate channels. GSM also is the only technology that provides incoming and outgoing data services, such as email, fax, and internet surfing. GSM makes use of a SIM card that allows memory portability between dumb GSM phones.

Handoff: The process by which the MTSO passes a cellular phone conversation from one radio frequency in one cell to another radio frequency in another. The handoff is performed so quickly that users usually never notice.

Hertz: A unit for expressing frequency which is the number of times a wave-like radio signal changes from maximum positive to maximum negative and then back to maximum positive again. 1 Hz = 1 cycle per second. 1 kilohertz (kHz) = 1,000 Hz; 1 megahertz (MHz) = 1,000 kHz or 1,000,000 Hz; 1 gigahertz (GHz) = 1,000 MHz or 1 million kHz or 1 billion Hz. AMPS (analog) cellular phones in Canada and the US use the 800 MHz band. Digital phones use either the 800 MHz or 1900 MHz (or 1.9 GHz) frequencies. Specifically, CDMA and TDMA use either 800 or 1900 MHz; iDEN uses only 800 MHz; GSM uses either the 850 or the 1900 MHz spectrum in North America. GSM uses 900, 1800, and/or 1900 MHz on other continents.

Hot spot: A place, such as a hotel, restaurant or airport, that offers Wi-Fi access, either free or for a fee.

iDEN: A modified TDMA technology used by Motorola. iDEN phones operate at 800 MHz and are offered by Telus Mobility in Canada and by Nextel in the US. Some of the newer iDEN phones also are hybrid with GSM technology and may roam overseas.

I-Mode: A popular wireless Internet service rolled out in 1999 by NTT DoCoMo Inc. in Japan. It's based on a simplified form of HTML and delivers packet-based information -- such as games, e-mail and even business applications -- to handheld devices.

IEEE: Institute of Electrical and Electronics Engineers Inc. is a nonprofit, technical professional association of more than 360,000 individual members in approximately 175 countries that is an authority in technical areas such as computer engineering and telecommunications. It developed the 802.11 specifications.

MAC: Every wireless 802.11 device has its own specific Media Access Control address hard-coded into it. This unique identifier can be used to provide security for wireless networks. When a network uses a MAC table, only the 802.11 radios that have had their MAC addresses added to that network's MAC table are able to get onto the network.

MTSO: Mobile Telephone Switching Office. The central switch that controls the entire operation of a cellular system. It is a sophisticated computer that monitors all cellular calls, tracks the location of all cellular-equipped vehicles traveling in the system, arranges handoffs, keeps track of billing information, etc.

NAM: The NAM or Number Assignment Module is the electronic memory in the cellular phone that stores the telephone number. Phones with dual- or multi-NAM features offer users the option of registering the phone with a local number in more than one market.

Paging: The act of seeking a cellular phone when an incoming call is trying to reach the phone.

PCS: Personal Communication Services. Essentially the same as cellular, but indicating a digital phone. See this FAQ for a more detailed description.

PRL: Referred Roaming List. A list of SID's kept inside a phone to permit roaming on other wireless networks. A service provider may set up roaming agreements with other service providers in different geographic regions and the PRL will try to locate one of these service providers' networks first when the home service provider is unavailable. PRL's do change so it's a good idea to ask for a PRL upgrade every 6 months or so if you do a lot of roaming outside your home service area.

Registration: The procedure that a cellular phone initiates to a base station to indicate that it is now active.

RFID: Radio frequency identification uses low-powered radio transmitters to read data stored in a transponder (tag) at distances ranging from one inch to 100 feet. RFID tags are used to track assets, manage inventory and authorize payments, and they increasingly serve as electronic keys for everything from autos to secure facilities.

Roaming: The ability to use your cellular phone outside your providers' home service area. Providers often set up Roaming Agreements with other providers in different geographic locations. A roaming agreement lets you seemlessly make calls in the other provider's geographic service area without operator intervention. Roaming agreements save customers money and time. Airtime incurred while roaming shows up on your monthly statement as an additional charge, unless your monthly plan includes roaming.

Roaming is never as cheap as your home airtime rates, but is provided as a short-term convience for a provider's customers. Sometimes a roaming agreement may not be in place and operator intervention is required to obtain a credit card number. This is usually much more expensive than a roaming agreement (up to $5/min compared to $1/min). Always contact your provider before roaming. Sometimes phones require roaming to be enabled to prevent fraudulent activity (e.g., anyone traveling to New York must have their provider unlock roaming restrictions for the duration of the trip); sometimes you need to know special codes to allow calls to be delivered to your phone; some roaming agreements allow the host provider to charge a daily roaming fee just to have the phone accessing their network; and some other providers charge airtime for the phone ringing even though you choose not to answer it.

SID: System Identification. A five digit number that indicates which service area the phone is in. Most carriers have one SID assigned to their service area.

SIM card: A small memory card not much bigger than half the length of your thumb. Used in GSM phones to hold your phone numbers and other information. Can be removed and inserted into other GSM phones, allowing you to keep your numbers and to place and receive phone calls.

Site survey: Done at the location for a new WLAN in an effort to avoid what could be time-consuming and costly problems down the road. It involves diagramming the network, checking the building and testing the equipment.

Smart phone: A wireless phone with text and Internet capabilities. Smart phones can handle wireless phone calls, hold addresses and take voice mail and can also access information on the Internet and send and receive e-mail and fax transmissions.

SMS: Short Message Service. A method of delivering a short (120-200 character) message to your digital cellular phone. GSM phones can also send SMS. A nice way to send a short message to someone without calling them. Private SMS services include weather and sports reports, stock quotes, and more. Usually people can either visit a SMS web page and type a short message which is sent to your phone or email your phone (e.g., 2509999999@telusmobilty.com). Some providers change additional monthly fees for the reception or transmission of SMS. See my Links page for a list of SMS services.

SP-lock: A lock placed on a cellular phone by some service providers to ensure that you can only use the phone with their services. More Information.

SSI: A Service Set Identifier is a sequence of characters unique to a specific network or network segment that's used by the network and all attached devices to identify themselves and allow devices to connect to the correct network when more than one independent network is operating in nearby areas.

Standby time: The amount of time you can leave your fully charged cellular phone turned on before the phone will completely discharge the batteries.

Symbian Ltd.: A joint venture among LM Ericsson Telephone Co., Motorola Inc., Nokia Corp. and Psion PLC to develop new operating systems based on Psion's EPOC32 platform for small mobile devices for wireless devices such as phones and handhelds.

Talk time: The length of time you can talk on your cellular phone without recharging the battery. The battery capacity of a cellular phone is usually expressed in terms of so many minutes of talk time OR so many hours of standby time. When you're talking, the phone draws additional power from the battery.

TDMA: Time Division Multiple Access. TDMA divides frequency bands available to the network into time slots, with each user having access to one time slot at regular intervals. TDMA thereby makes more efficient use of available bandwidth than the previous generation AMPS technology. Available in either 800 or 1900 MHz frequencies.

UWB: Ultrawideband, also called digital pulse, is a wireless technology for transmitting digital data over a wide swath of the radio frequency spectrum with very low power. Because of the low power requirement, it can carry signals through doors and other obstacles that tend to reflect signals at more limited bandwidths and a higher power. It can carry large amounts of data and is used for ground-penetrating radar and radio locations systems.

Voice Channel: A channel used for transmission of voice data from a base station to a cellular phone (forward voice channel) or from a cellular phone to a base station (reverse voice channel)

WAP: The Wireless Application Protocol is a set of specifications, developed by the WAP Forum, that lets developers using Wireless Markup Language build networked applications designed for handheld wireless devices. WAP was designed to work within the constraints of these devices: a limited memory and CPU size, small, monochrome screens, low bandwidth and erratic connections. WAP is a de facto standard, with support from more than 200 vendors.

War driving: Typically refers to driving around with a wireless-enabled laptop and antenna to find places where it's possible to access exposed wireless networks. These are usually company networks that extend beyond the physical infrastructure of the company and are left unprotected.

War chalking: Marking buildings or sidewalks with chalk to show others where it's possible to access an exposed company wireless network. These access points are typically found through war driving (see above).

WEP: Wired-Equivalent Privacy protocol was specified in the IEEE 802.11 standard to provide a WLAN with a minimal level of security and privacy comparable to a typical wired LAN, using data encryption. It's now widely recognized as flawed because of an insufficient key length and other problems and can be cracked in a short time with readily available tools.

Wi-Fi: Wireless fidelity is the generic term for 802.11 technology (see 802.11 above).

Wi-Fi Alliance: A nonprofit international association formed in 1999 to certify interoperability of WLAN products based on the IEEE 802.11 specification. Currently, the Wi-Fi Alliance has over 200 member companies from around the world, and over 1,000 products have received Wi-Fi certification since certification began in March of 2000. The goal of the Wi-Fi Alliance's members is to enhance the user experience through product interoperability.

WiMax: Popular name of the 802.16 wireless metropolitan-area network standard that's currently being developed. WiMax, which will have a range of up to 31 miles, is primarily aimed at making broadband network access widely available without the expense of stringing wires (as in cable-access broadband) or the distance limitations of Digital Subscriber Line.

Wireless Data: A service that allows you to send digital data over a cellular phone. Analog phones require a cellular modem; digital phones do not. Not offered by all providers.

WLAN: Wireless local-area networks use radio waves instead of a cable to connect a user device, such as a laptop computer, to a LAN. They provide Ethernet connections over the air and operate under the 802.11 family of specifications developed by the IEEE.

WML: Wireless Markup Language is like the Internet programming language HTML. It delivers Internet content to small wireless devices, such as browser-equipped cellular phones and handheld devices, which typically have very small displays, slow CPUs, limited memory capacity, low bandwidth and restricted user-input capabilities.

WPA: Wi-Fi Protected Access is a data encryption specification for 802.11 wireless networks that replaces the weaker WEP. It improves on WEP by using dynamic keys, Extensible Authentication Protocol to secure network access, and an encryption method called Temporal Key Integrity Protocol to secure data transmissions.

Zigbee: Zigbee is a wireless standard which is cheap and has low power consumption. With Zigbee it is possible to construct a network which can revolutionise the use of radio chips. Zigbee can for instance be used for building automation, including electrical and heat controls.
Zigbee is based on the wireless IEEE 802.15.4 standard and is more simple and cheap to operate that WiFi and Bluetooth. Zigbee was designed so that it is able to submit a limited volume of date at a speed of maximum 250k bps.

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