Ad hoc network: A type of temporary computer-to-computer connection. In ad hoc mode, terminals set up a wireless connection directly to another terminals without having to connect to a Wi-Fi access point or router. In Latin, ad hoc literally means "for this," meaning "for this special purpose" and also, by extension, improvised or impromptu.

Air Interface: In wireless communications, the air interface is the radio frequency (RF) part of the network that transmits signals between base stations and end-user equipment. The air interface is defined by specifications for a specific format such as GSM, cdma2000, GPRS, or W-CDMA.

Air interface is also called Um Interface.


Advanced Mobile Phone Service (AMPS): The original analogue “cellular” service transmission standard first deployed in the United States, still used as a default standard for cellular systems in the U.S,  Canada and parts of central and south America.


Analogue: The traditional method of adapting radio signals so they can carry information. AM (Amplitude Modulation) and FM (Frequency Modulation) are the two most common analog systems.   Analog has largely been replaced by digital technologies, which are more secure, more efficient and provide better quality. 

Authentication Center (AUC): Refers to  a function to authenticate each SIM card that attempts to connect to the GSM core network (typically when the phone is powered on). Once the authentication is successful, the HLR is allowed to manage the SIM and services described above. An encryption key is also generated by the AUC that is subsequently used to encrypt all wireless communications (voice, SMS, etc.) between the mobile phone and the GSM core network.

Base Station: Base Station Base station (BS), also called cell site, is the local cellular tower and radio antenna (including the radios, controller, switch interconnect, etc.) that handles communication with mobile users in a particular area or cell. A cellular network is made up of many cell sites or base stations, all connected back to the switch via landline or microwave links.

Bluetooth:  The name for a technological standard (a communications protocol) that enables mobile devices equipped with a special chip to send and receive information wirelessly.  Using Bluetooth, electronic devices such as desktop computers, wireless phones, electronic organizers and printers can communicate over short-ranges using the 2.4 GHz spectrum band.

Broadband:  A transmission facility having a bandwidth (capacity) sufficient to carry multiple voice, video or data channels simultaneously.  Broadband is generally equated with the delivery of increased speeds and advanced capabilities, including access to the Internet and related services. The threshold hold speed for broadband is usually determined by the telecommunication regulator  and may therefore differ from country to country.

CDMA (Code Division Multiple Access): An air interface technology that was developed by the U.S. military and commercialized by the U.S. company Qualcomm. CDMA supports SMS with a message length of 120 characters. With CDMA, each conversation is digitized and then tagged with a code. The mobile phone receives a signal to locate that particular code and it then deciphers the conversation off the airwaves. CDMA codes each conversation expanding it 128 times, making it easy to decipher at the receiving end.

CDMA2000 1XEV:  represents the next step in the evolution of CDMA2000. Approved by the International Telecommunications Union (ITU), a standards body based in Geneva, as a 3G technology to provide data and voice services together, with data rates of up to 3.09 Mbps.


CDMA2000 1XEV-DO: (Evolution Data-Only). CDMA2000 1XEV represents the second step in the evolution of CDMA2000. Commercially launched in 2001, offers data speeds of up to 2.4 Mbps.   CDMA2000 1XEV-DV: (Evolution Data-Voice).


CDMA2000 1XRTT: The first step in the evolution to 3G is cdma2000 1X, which improves packet data transmission capabilities and speeds in the network, and also boosts voice capacity. (Speed of up to 307 kbps.)


Cell Broadcast (CB):  Also known as Short Message Service - Cell Broadcast (SMS-CB), is a one-tomany geographically focused messaging service, whereas the Short Message Service - Point to Point (SMS-PP) is a one-to-one and one-to-a-few service. Cell Broadcast is designed for simultaneous delivery of messages to multiple users in a specified area. CB is a mobile technology feature defined by the ETSI’s GSM committee and is part of the GSM standard. Cell Broadcast messaging is also supported by UMTS, as defined by 3GPP.

Cell: The basic geographic unit of wireless coverage. Also, shorthand for generic industry term "cellular." A region is divided into smaller "cells," each equipped with a low-powered radio transmitter/receiver.  The radio frequencies assigned to one cell can be limited to the boundaries of that cell. As a wireless call moves from one cell to another, a computer at the Mobile Telephone Switching Office (MTSO) monitors the call and at the proper time, transfers the phone call to the new cell and new radio frequency. The handoff is performed so quickly that it’s not noticeable to the callers.

Channel: Refers to a one-way telecommunications link or transmission medium through which information or signal is transmitted from a sender (or transmitter) to a receiver. They may be either physical or logical depending on the application. A Radio Frequency (RF) channel is a physical channel, whereas control and traffic channels within the RF channel would be considered logical channels. 


Circuit Switched Data(CSD):  One technological approach used for the exchange of data. A circuit connection is made that is exclusively reserved for the individual’s use. This can be inefficient, as many communications do not require a dedicated communications channel, but only brief connectivity, for the transmission of short messages.

Co-location: Placement of multiple antennas at a common site.  Some companies act as brokers or cell site managers, arranging cell sites and coordinating many carriers' antennas at a single cell site. Co-location creates an environment with few towers since many operators can share one site.

Downlink: The transmission path from the base station down to the mobile station.


Dual Band:  A wireless handset that works on more than one spectrum frequency, e.g., in the 800 MHz frequency and 1900 MHz frequency bands.


Dual Mode: A wireless handset that works on both analog and digital networks.

EDGE: Enhanced Data Rate for Global Evolution is an evolutionary step in the GSM-development path for faster delivery of data, delivered at rates up to 384 Kbps. The standard is based on the GSM technology platform and uses the TDMA approach.


Enhanced Messaging Service (EMS):  utilizes SMS but adds the ability to incorporate simple graphics, pictures, animations and sound. With this, the user can add an actual emotion to his/her message. Give someone a full birthday wish (with the text, the actual song, and a graphic of a birthday cake).


Evolution Data Only (EVDO):  A high-speed network protocol used for wireless Internet data communications. The EVDO protocol supports asymmetric communications, allocating a majority of this bandwidth to downloads. EVDO is based on the 1xRTT standard, providing data transmission speeds wirelessly up to 3.1Mbps. It is for always-on mobile packet data and voice for GPRS-enabled cellular phones, networks and handheld devices.

Frequency Division Multiplexing(FDM): Frequency-division multiplexing is a method in which numerous signals are combined for transmission on a single communications channel. Each signal is assigned a different frequency (subchannel) within the main channel.

  Frequency hopping works by modulating a data signal with a carrier signal that hops from frequency to frequency as a function of time over a wide band of frequencies. With 802.11 FHSS, the carrier frequency hops over the 2.4GHz frequency band between 2.4GHz and 2.483GHz. The signal stops long enough at each frequency to transmit data for an amount of time based on the dwell time set as a configuration parameter .

Fixed Wireless:  The over-the-air transmission of information to and from systems and end-user equipment that are stationary, rather than mobile. Operators of fixed wireless networks potentially can offer broadband services without having to lay expensive cable systems or deal with the complexities of mobility management. 

Global System for Mobile Communications(GSM): A digital mobile phone standard used extensively in Europe, the Middle East, Africa, Asia and in parts of America and Canada. First introduced in 1991, the GSM standard has been deployed at three different frequency bands: 900 MHz, 1800 MHz and 1900 MHz. GSM 1900 is primarily deployed in North America. Named after its frequency band around 900 MHz, GSM-900 has provided the basis for several other networks using GSM technology. GSM uses narrowband TDMA which allows eight simultaneous calls on FDM channel of 200KHz. Along with CDMA and TDMA it represents the second generation of wireless networks.

General Packet Radio Service (GPRS): A packet technology approach that enables high-speed wireless Internet and other GSM-based data communications. GPRS makes efficient use of available radio spectrum for transmission of data.  

Global Positioning System (GPS): A worldwide satellite navigational system, made up of 24 satellites orbiting the earth and their receivers on the earth’s surface.  The GPS satellites continuously transmit digital radio signals, with information used in location tracking, navigation and other location or mapping technologies.


GSM 1800: also known as DCS 1800 or PCN, is a mobile network working on a frequency of 1800 MHz. It is used in Africa, Europe, Asia-Pacific and Australia. 


GSM 1900: also known as PCS 1900, is a mobile network working on a frequency of 1900 MHz. It is used in the US and Canada and is scheduled for parts of Latin America and Africa. 


GSM 900:  or just GSM, is the world's most widely used digital network -- now operating in over 100 countries around the world, particularly in Europe and Asia Pacific.

Handoff: The process when a wireless network automatically switches a mobile call to an adjacent cell site.

Hot Spot: An area, such as a hotel, restaurant or airport, that offers Wi-Fi access, either free or for a fee.

HSCSD (High Speed Circuit Switched Data): In using HSCSD a permanent connection is established between the called and calling parties for the exchange of data. Being circuit switched, HSCSD is more suited to real-time applications such as videoconferencing and multimedia than 'bursty' type applications such as computer data, which are more suited to packet switched data.  

Home Location Register (HLR):  The central database in a GSM or CDMA network contains details of all mobile phone subscribers authorized to use the GSM core network. HLR store details of every SIM card issued by the mobile phone operator. Each SIM has a unique identifier called an  International Mobile Subscriber Identity (IMSI) which is the primary key to each HLR record. The HLR data is stored for as long as a subscriber remains with the mobile phone operator.
Data stored in the HLR against an IMSI record include:
(a) GSM services that the subscriber is allowed to access;
(b) GPRS settings to allow the subscriber to access packet services;
(c) Current location of subscriber (VLR and serving GPRS support node/SGSN); and
(d) Call divert settings applicable for each associated MSISDN.

Interconnection: Connecting one wireless network to another, such as linking a wireless carrier's network with a local telephone company’s network.

International Mobile Equipment Identity (IMEI): A number unique to every GSM and UMTS mobile phone. It is usually found printed on the phone underneath the battery and can also be found by dialing the sequence *#06# into the phone. The IMEI number is used by the GSM network to identify valid devices and therefore can be used to stop a stolen phone from accessing the network. For example, if a mobile phone is stolen, the owner can call his or her network provider and instruct them to "ban" the phone using its IMEI number. This renders the phone useless, regardless of whether the phone's SIM is changed.


Interoperability: The ability of a network to coordinate and communicate with other networks, such as two systems based on different protocols or technologies.

Local Area Network (LAN): Local Area Network (LAN) is a small data network covering a limited area, such as a building or group of buildings. Most LANs connect workstations or personal computers.  This allows many users to share devices, such as laser printers, as well as data.  The LAN also allows easy communication, by facilitating e-mail or supporting chat sessions.

Long Term Evolution (LTE), sometimes also referred to as 3G LTE or Super-3G: A 3GPP radio technology evolution architecture. Its full name is UTRA-UTRAN Long Term Evolution (LTE) and 3GPP System.

Mobile Switching Centre (MSC):  Refers to the system that provides telephony switching services and controls calls between telephone and data systems. The MSC switches all calls between the mobile and other  PSTN (other mobile operators and fixed operators) and other mobiles and performs additional functions like billing.


Mobile Telephone Switching Office (MTSO): The central computer that connects wireless phone calls to the public telephone network. The MTSO controls the series of operations required to complete wireless calls, including verifying calls, billing and antenna handoffs.


Mobile Virtual Network Operator (MVNO): A company that buys network capacity from a mobile network operator in order to offer its own branded mobile subscriptions and value-added services to customers. Example of MVNO in Kenya is EQUITEL


Multimedia Messaging Service (MMS): allows telephone users to send messages containing text, pictures, sounds, and other rich media between cell phones.


Number Portability:  The ability of a customer to retain their telephone number when changing service providers in a specific area, whether changing from one wireless company to another, one wireline company to another, or between wirelesss and wireline companies.


Orthogonal Frequency Division Multiplexing (OFDM): A system for the transmission of digital message elements spread over multiple channels within a frequency band, in order to achieve greater throughput while minimizing interference and signal degradation through the use of multiple antennas.

Packet Data: Information that is reduced into digital pieces or ‘packets’, so it can travel more efficiently across networks, including radio airwaves and wireless networks.


Packet Switched Data (PSD): A technological approach in which the communication “pipe” is shared by several users, thus making it very efficient. The data is sent to a specific address with a short delay. This delay depends on how many users are using the pipe at any one time as well as the level of priority. PSD is the technology used for data communication across the Internet and makes more efficient use of the network.

Packet: A piece of data sent over a packet-switching network, such as the Internet.  A packet includes not just the data comprising the message but also address information about its origination and destination.


Personal Communications Services (PCS): A broad family of wireless services, commonly viewed as including two-way digital voice, messaging and data services. 

Personal Digital Assistant (PDA): A portable computing device capable of transmitting data. These devices offer services such as paging, data messaging, email, computing, faxes, date books and other information management capabilities.


Personal Identification Number (PIN): An additional security feature for wireless phones, much like a password.  Programming a PIN into the Subscriber Information Module (SIM) on a wireless phone requires the user to enter that access code each time the phone is turned on.

Piconet: An ad hoc network that links a wireless user group of devices using Bluetooth technology protocols. A piconet consists of two or more devices occupying the same physical channel (synchronized to a common clock and hopping sequence).

Protocol:  A standard set of definitions governing how communications are formatted in order to permit their transmission across networks and between devices.

Public Switched Telephone Network (PSTN): The network of the world's public circuit-switched telephone networks, providing commercial telephony services. Originally as a network of fixed-line analogue telephone systems, the PSTN is now almost entirely digital and includes mobile as well as fixed telephones.


Roaming: A facility including protocols that allows users to continue to make and receive calls when operating in another carrier’s service coverage area.

Scatternet is a type of ad hoc computer network consisting of two or more piconets. The terms "scatternet" and "piconet" are typically applied to Bluetooth wireless technology.

Short Message Service Centre (SMSC):The hardware device submitting the messages. Currently, SMSC devices support binary formats. A software module called the SMS gateway is used to give instructions to the SMSC. The protocol described in this draft provides a standard for service providers to interact with SMS gateways or SMS centers.

Short Messaging Service (SMS): The service that allows the transmission of short text messages among mobile devices such as cell phones, fax machines and BlackBerry devices. SMS was originally designed as part of GSM, but is now available on a wide range of networks, including 3G networks. There are two forms of SMS: Short Message Service - Point-to-Point (SMS-PP) and Short Message Service - Cell Broadcast (SMS-CB). The message length is 140 bytes. Larger contents (known as long SMS or concatenated SMS) can be sent segmented over multiple messages, in which case each message will start with a user data header (UDH) containing segmentation information.

Smart Antenna: A wireless antenna with technology that focuses its signal in a specific direction. Wireless networks use smart antennas to reduce the number of dropped calls, and to improve call quality and channel capacity.


Smart Phone:  Wireless phone with advanced data features and often with a keyboard. What makes the phone "smart" is its ability to manage and transmit data in addition to voice calls.


Spectrum Allocation: Process whereby the telecommunication regulator, e.g Communications Authority of Kenya designates frequencies for specific uses, such as personal communications services and public safety.  Allocation is typically accomplished through lengthy proceedings, which attempt to adapt allocations to accommodate changes in spectrum demand and usage.

  Subrate: A rate lower than the normal rate. A channel bank typically derives multiple 64-kbps voicegrade channels from a circuit. If multiple low-speed data applications require less bandwidth, a sufficiently sophisticated time division multiplexer (TDM mux) can subdivide a channel into multiple subrate data channels.

Spread Spectrum: A method of transmitting a radio signal by spreading it over a wide range of frequencies.  This reduces interference and can increase the number of simultaneous users on one radio frequency band.


Third-Generation (3G): A general term that refers to technologies which offer increased capacity and capabilities delivered over digital wireless networks. 

Time Division Multiple Access (TDMA): A technological standard that permits the transmission of information by dividing calls into time slots, each one lasting only a fraction of a second. Each call is assigned a specific portion of time on a designated channel.  By dividing each call into timed ‘packets,’ a single channel can carry many calls at once.


Tri-Band Handset: Phones that work on multiple frequencies, typically in the 1900 MHz, 800 MHz, and 900 MHz frequencies used in the U.S. and elsewhere.


Tri-Mode Handset:  Phones that operate in different modes, such as the CDMA, TDMA, and analogue standards.


Universal Mobile Telecommunications Systems (UMTS): This is third generation technology generally based on W-CDMA (Wideband Code Division Multiple Access). UMTS promises a communications speed between 384 kbps and up to about 2 Mbps.


Virtual Private Network (VPN): Private networks that are configured within a public network. Carriers build VPNs that appear as private national or international networks to the customer, but physically share backbone trunks with other customers. VPNs enjoy the security of a private network via access control and encryption, while taking advantage of the economies of scale and built-in management facilities of large public networks. VPNs have been built over X.25, Switched 56, frame relay and ATM technologies. The VPN adds an extra layer of security.

Visitor Location Register (VLR):  A database of the subscribers who are active in the jurisdiction of a Mobile Switching Center (MSC).  Each Base Transceiver Station (BTS)  in the network is served by exactly one VLR, hence a subscriber cannot be present in more than one VLR at a time. The data stored in the VLR is received from the HLR, or the Mobile station (MS).
Whenever an MSC detects a new MS in its area of jurisdiction, in addition to creating a new record in the VLR, it also updates subscriber's records in the  HLR of the mobile subscriber by updating the location of that MS.
Data stored in the VLR  include:
(a) IMSI (the subscriber's identity number);
(b) Authentication data. MSISDN (the subscriber's phone number);
(c)  GSM services that the subscriber is allowed to access;
(d) Access point (GPRS) subscribed;
(e) The HLR address of the subscriber.

Voice over Internet Protocol (VoIP ): VoIP is not simply capable of delivering voice over IP, but is also designed to accommodate two-way video conferencing and application sharing as well. Based on IP technology, VoIP is used to transfer a wide range of different type traffic.


Wide Area Network (WAN): A general term referring to a large network spanning a country or around the world. The Internet is a WAN. A public mobile communication system such as a cellular or PCS network is a WAN.


Wideband Code Division Multiple Access (W-CDMA): One of the two 3G standards that makes use of a wider spectrum than CDMA and therefore can transmit and receive information faster and more efficiently.

Wi-Max: A wireless technology based on the IEEE 802.16 standard providing metropolitan area network connectivity for fixed wireless access at broadband speeds.


Wireless Application Protocol (WAP): An open standard for communication between handsets and the Internet. WAP is a wireless communications environment for delivering Web data to wireless terminals with minimal screen display. An initiative started by Unwired Planet, Motorola, Nokia and Ericsson to develop a standard for wireless content delivery on the next generation of mobile communicators. WAP strips all but graphics for display on small screens, such as mobile phones. A mini-browser is an integral part of WAP enabled phones. WAP enabled phones first appeared in Europe at the end of 1999.

Wireless Fidelity (WiFi):  WiFi provides wireless connectivity over unlicensed spectrum (using the IEEE 802.11a or 802.11b standards), generally in the 2.4 and 5 GHz radio bands. Wi-Fi offers local area connectivity to WiFi-enabled devices(smart phones, computers, etc).


Wireless Internet:  A general term for using wireless services to access the Internet, e-mail and/or the World Wide Web.


Wireless Local Area Network (WLAN): Using radio frequency (RF) technology, WLANs transmit and receive data wirelessly in a certain area.  This allows users in a small zone to transmit data and share resources, such as printers, without physically connecting each computer with cords or wires.

Wireless Local Loop (WLL):  Asystem that connects wireless users to the public switched telephone network (PSTN) using wireless technology and other circuitry to complete the "last mile" between the wireless user and the exchange equipment.  Wireless systems can often be installed faster and cheaper than traditional wired systems.

Wireless Regional Area Network (WRAN or IEEE 802.22), is a standard for  using white spaces in the TV frequency spectrum. The development of the IEEE 802.22 WRAN standard is aimed at using cognitive radio (CR) techniques to allow sharing of geographically unused spectrum allocated to the television broadcast service, on a non-interfering basis, to bring broadband access to hard-to-reach, low population density areas, typical of rural environments, and is therefore timely and has the potential for a wide applicability worldwide.
Wireless Sensor Network (WSN) is a wireless network consisting of spatially distributed autonomous devices using sensors to monitor physical or environmental conditions. A WSN system incorporates a gateway that provides wireless connectivity back to the wired world and distributed nodes.

WPAN  ( or Wireless Personal Area Network) is a wireless network of interconnected devices centred on an individual person's workspace. WPAN is based on the standard IEEE 802.15. The two kinds of wireless technologies used for WPAN are Bluetooth and Infrared Data Association.

Prof. James Kulubi