Cellular-terms.doc

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Cellular-terms.doc

  1. 1. Cellular Telecommunications Glossary - a glossary of terms used with cell phone or cellular telecommunications technology http://www.radio-electronics.com/info/cellulartelecomms/index.php 1G First generation. This term refers to the first generation cellular systems that were based around analogue technology. The voice channel typically used frequency modulation, and they used FDMA techniques. 1XRTT This refers to a CDMA2000 operating mode which uses the basic chip rate of 1.2288 Mcps and a channel bandwidth of 1.25 MHz. 1XRTT systems are often abbreviated to just 1X. 2G Second Generation. This term refers to the second forms of cellular telecommunications systems that were introduced. The systems were digital and were oriented to voice with only low speed data services. Systems such as GSM and US-TDMA used a mixture of TDMA and FDMA techniques. IS-95 / cdmaOne was the first CDMA system. 3G Third generation. The designation for systems following the 2G systems and they offer high speed data services in addition to the basic voice capability. Typically they use CDMA techniques and include W- CDMA, CDMA2000, and TD-SCDMA. 3GPP Third Generation Partnership Project. The group that was set up to produce globally applicable Technical Specifications and Technical Reports for a 3rd Generation Mobile System based on evolved GSM core networks. It produced the standards for W-CDMA (UMTS). Later the scope of the organization was widened to include the maintenance and development of the GSM Technical Specifications and Reports. 3GPP2 Third Generation Partnership Project 2. The organization that is responsible for the specifications for the 3G developments for CDMA2000. 3XRTT The CDMA2000 operating mode at 3 times the basic chip rate of 1.2288 Mcps and having a bandwidth three times that of the 1X system. 8-PSK
  2. 2. Modulation using Phase Shift Keying with 8 states allowing for coding using 8 bit combinations. This allows for higher data rates to be sent than PSK systems using fewer states, although better signal to noise ratios are required to ensure an acceptable bit error rate. A-bis The standard for the link between the base transceiver station and the base-station controller. ACELP Algebraic Code Excited Linear Prediction A vocoder used in GSM and NA-TDMA. AFLT Advanced Forward Link Trilateration. A position location technique used on CDMA networks. It uses the measured time of arrival of radio signals to the mobile from the base stations. Using this information the network is able to determine the location of the mobile to an accuracy of around 200 metres. A-GPS Assisted GPS. A position location technique used for cellular telecommunications that is based around the Global Positioning System (GPS). To provide a faster time to first fix and signal acquisition under poor signal conditions, assistance data is provided by the network to the mobile. AMPS Advanced Mobile Phone System. The first generation analogue cellular system used in North America and many other countries around the globe. It used a 30 kHz channel spacing, and FM was used to carry the voice channel. ARIB Association of Radio Industries and Businesses. The body responsible for telecommunications standards in Japan. ARPU Average Revenue Per User. The figure for the average revenue generated by each user on a mobile phone network. AuC Authentication Centre. It contains secure information about subscribers to a network including the permanent key of the subscriber’s SIM card. This information enables it to provide authentication and encryption parameters that verify the user's identity and ensure the confidentiality of each call protecting users and network operators from fraud. AT Access terminal. This refers to the handset or “phone?used on a CDMA2000 1xEV-DO network. It is called an Access Terminal because EV-DO is a data only service.
  3. 3. AWGN Additive White Gaussian Noise. An emulation of “white?noise often used in testing receiver sensitivity. It is also used for testing CDMA systems because the noise simulates that which is generated by additional CDMA signals on the same channel. Baseband The signal or signals that are used to modulate the radio carrier in the transmitter, and in this way the information can be carried by the radio signal. They may often be referred to as modulation. The baseband signals are recovered by the receiver by demodulating the received radio signal. BSC Base Station Controller. Mobile network component that contains all the logic used to control the operations of the BTS and acts as an interface between the BTS and the MSC. BTS Base Transceiver Station. The term for a mobile phone base station. A BTS contains the transmit and receive technology and also the antennas to supply a cellular radio cell. CDG CDMA Development Group. This is the consortium of companies that was formed to promote the adoption, development and evolution of CDMA (i.e. cdmaOne and CDMA2000) wireless technology. CDMA Code Division Multiple Access. A cellular telecommunications access technology using direct sequence spread spectrum techniques. By using DSSS it enables multiple users to gain access to a network by allocating them different spreading codes. CDMA2000 This is a family of 3G cellular telephone standards. It includes CDMA2000 1X and beyond this the CDMA2000 1xEv, evolution technologies that offer higher data rate services. CDMA2000 1X The first phase of CDMA2000 offering voice and data services. Peak data rates of 307 kbps can be achieved using a single channel and when two are used this increases to 614 kbps. CDMA2000 1xEV The Evolution of CDMA2000 beyond 1X offering higher data rates. The two schemes that are currently live or being developed are CDMA2000 1xEV-DO and CDMA2000 1xEV-DV. CDMA2000 1xEV-DO
  4. 4. This is the Data only or Data Optimized evolution for CDMA2000. As the name implies this standard is optimized for data only and can offer data rates up to 2.45 Mbps under Release 0 of the standard or 3.1 Mbps under Release A. It uses separate channels from the existing 1X standard, and if voice traffic is to be handled an “Access Terminal?capable of using 1X must be used and this is carried on a different channel to the data. The EV-DO standard is defined under IS-856. CDMA2000 1xEV-DV This is the Data and Voice evolution for CDMA2000. It supports both data and voice on the same channel and data speeds of up to 3.1 Mbps can be achieved. The system is defined under IS-2000. The first offering appears in Release C of the standard where the high data rate is only available in the downlink, the uplink allows for data at the same rate as 1X. Release D allows for the high speed data in both directions. cdmaOne This is the brand name for the second-generation CDMA system defined under the IS-95 standard. It operates in the 800 MHz or 1.9 GHz radio frequency bands and uses 1.25 MHz-wide channel bandwidth. CELP Code Excited Linear Prediction. A digital voice coding scheme that predicts the signal using past samples. CEPT The European Conference of Postal and Telecommunications Administrations (Conférence Européenne des Administrations des Postes et des Telecommunications). It is the European telecommunications authority and it exclusively addresses sovereign/regulatory matters for postal and telecommunications activities within Europe. Chip A single bit of a pseudo noise sequence. Chip rate The rate at which chips are sent. For CDMA networks where signals need to be spread over bandwidths of 1 MHz and more chip rates are measured in millions of chips per second, Mcps. Churn This is the term for subscribers leaving one cell phone operator to go to another. Circuit switched data This is the technique that is used when a complete circuit is dedicated to a particular data channel. The destination address is implicitly defined by the circuit that is selected. It offers a simple solution to sending data over a channel, although it is not as efficient as packet switched data because channel usage can be low and the channel cannot be shared. CODEC COder/DECoder.
  5. 5. A circuit used to convert analogue signals such as voice or video into a digital format for transmission over digital medium. A receiver it also reconverts the signals to the original analogue form. The circuit or algorithm used may also include compression and decompression to reduce the level of data that needs to be transmitted. Codecs are widely used in mobile phones and different coding algorithms used dependent upon the phone system used and the application. COFDM Coded Orthogonal Frequency Division Multiplex. A modulation scheme using a number of closely spaced orthogonal carriers. The data is spread over these carriers and as a result it is resilient to multi-path and other forms of interference. It is used for various forms of digital broadcasting and is being considered for the use with the fourth generation cellular telecommunications systems. Correlation This is a process that occurs when using spread spectrum techniques and it is the process of synchronizing the phase of a local PN sequence within a radio receiver with that of the incoming spread signal in order to “despread?and recover the narrowband data signal. CTIA Cellular Telecommunications and Internet Association. It offers many services including operating an equipment testing and certification program. Downlink The transmission from cell phone base station to mobile phone or terminal. This term is normally associated with GSM or UMTS networks. DSSS Direct Sequence Spread Spectrum. A modulation technique where a pseudo noise sequence is multiplied with data to be transmitted and this sequence is used to phase modulate a carrier. The fact that the PN sequence has a higher data rate than the data means that the bandwidth of the transmission is increased while the spectral power density is lowered. The resulting RF signal has a noise-like spectrum, and in some applications it can be intentionally made to look like noise to unauthorized listeners. To regenerate the wanted data at the receiver the signal is “despread” by correlating it with a pseudorandom sequence. This is identical to the one used during transmission and it must also be in synchronization. Direct sequence spread spectrum is used as the basis of CDMA cellular phones where different users are allocated different spreading codes. DTX Discontinuous Transmission. A scheme where a mobile only transmits when the user is talking. This has the advantages that it saves battery life and reduces interference levels, but it can clip the speech making it sound less natural. During the quiet periods background noise has to be added at the receiver to give it a more natural sound. EDGE
  6. 6. Enhanced Data rates for GSM Evolution (also referred to as Enhanced Data rates for Global Evolution). The system utilizes the basic GSM / GPRS network, but uses 8PSK modulation rather than GMSK to enable peak data rates of 384 kbps to be achieved. EIR Equipment Identity Register The entity within a GSM system that stores information about the status of a mobile, for example if it has been stolen. E-OTD Enhanced Observed Time Difference. A location technology in which the mobile measures the time difference of the arrival of signals from the base station. Using this information the network is able to calculate the position of the mobile. Erlang This is a measure of traffic or load in a telecommunications system. 1 Erlang is equivalent to one telephone line being permanently used. E-TACS Extended TACS. An extension to the basic TACS system where further channels were allocated to create further capacity. ETSI European Telecommunications Standards Institute. The European Telecommunications Standards Institute that is responsible for telecommunications standards. FDMA Frequency division multiple access. A technique that that enables multiple users to access a mobile phone network by allocating them different frequencies or channels. FDD Frequency Division Duplex. A technique to allow simultaneous transmission to and from the handset where the uplink and downlink transmissions are separated by using different frequencies. Forward link The transmission from the cell phone base station to the mobile phone or temrinal. This term is normally associated with cdmaOne (IS-95) or CDMA2000 (IS-2000) networks. GMSK Gaussian Minimum Shift Keying. The form of phase shift keying used for GSM cell phone transmissions. It is a form of minimum shift keying (MSK) that is passed through a filter with a Gaussian curve to reduce its bandwidth.
  7. 7. GPRS General Packet Radio Service. An evolution of GSM system that uses packet data to provide a more efficient use of the available data capacity and thereby enables maximum data speeds of up to 115 kbps to be achieved. GPS Global Positioning System. A satellite based system for providing accurate position information. It uses the US DoD Navstar satellites system consisting of a constellation of 24 active satellites that transmit signals that enable receivers on earth to determine the position on the earth. GSM Global System for Mobile telecommunications. A digital TDMA (2G) system developed in Europe and now widely used around the world. Handoff A term used in the USA to describe the process of transferring a mobile from one cell to another while it is in the middle of a call. Handover A term used in Europe to describe the process of transferring a mobile from one cell to another while it is in the middle of a call. Hard Handover A term normally associated with CDMA networks for a form of handover where the mobile has to change channels, i.e. frequency to complete the handover. HLR Home Location Register. A central database of permanent subscriber information for a mobile network. It is located on the “home” network for the particular user. HSDPA High Speed Downlink Packet Access. An enhancement to the W-CDMA standard which enables faster data rates (up to 14 Mbps) to be achieved on the downlink from the Node B to the handset. HSUPA High Speed Uplink Packet Access. An enhancement to the W-CDMA standard which enables faster data rates to be achieved on the uplink from handset to the Node B. IMEI International Mobile Equipment Identity. A serial number contained within a mobile that is used by the network to check its status, i.e. whether it is has been stolen.
  8. 8. IMSI International Mobile Subscriber Identity. The number contained within the SIM card and used on the GSM system to identify a subscriber. It relates the subscriber to the phone number. IMT-2000 International Mobile Telecommunications standard 2000 that defines the third generation mobile phone technology. IS-95 The specification for the first cellular system to use CDMA techniques. Known under the brand name cdmaOne there were two releases of the standard, namely IS-95A and IS-95B. The second of B version is able to accommodate data at rates up to 115 kbps whereas the A version can only accommodate speeds of 14.4 kbps. IS-2000 The standard for the CDMA2000 3G cellular telecommunications system written by the TIA. ITU The International Telecommunications Union. It is an international organization that is run under the auspices of the United Nations. Within the organization governments and the private sector can work together to coordinate the operation of telecommunication networks and services and advance the development of communications technology. The ITU created the recommendations that defined the Third Generation (3G) mobile phone technology. MAC Medium Access Control. The networking protocol layer that is used to control transmission requests, authentication and other overheads in local area network. It is widely used in cellular telecommunications (mobile phone) applications. MIP Mobile Internet Protocol A scheme allowing users wither using computers connected to a "foreign network" whether by wire or cellular phone to connect using a mobile IP address. In this way they are able to maintain their connection even as they move from one base station and PDSN to the next. MMS Multimedia Messaging Service. It is an extension of SMS. It has a much greater capacity allowing larger quantities of text as well as attached images and audio files to be sent and as a result it is often referred to as picture messaging. MSC Mobile Switching Centre.
  9. 9. Interface between the base station system, i.e. the BTS and the switching subsystem of the mobile phone network. MSK Minimum Shift Keying. This is a form of modulation where the phase changes are undertaken at the zero crossing points. By adopting this technique the sidebands and hence the bandwidth required is reduced. It also enables coherent techniques to be used to gain a 3 dB advantage. MSK signals are often filtered to further reduce the bandwidth. One example of this is GMSK. NAMPS Narrowband AMPS. A cell system based on the AMPS analog mobile phone system but using a 10 kHz channel spacing rather than 30 kHz. By adopting a narrower channel bandwidth spectrum efficiency could be improved to cater for the increased usage, although voice quality was impaired. NA-TDMA North American Time Division Multiple Access. A 2G digital cell phone system using TDMA techniques. It used a 30 kHz channel spacing to provide compatibility with the frequency plans of AMPS. It was also known by names including Digital AMPS (DAMPS) and US Digital Cellular (USDC). NMT Nordic Mobile Telephone. An analogue (1G) cellular system that used either the 450 MHz or 900 MHz bands. It was developed for deployment in Scandinavia, but its use spread to many other countries. It was the first cellular system to be used commercially. Node B The name for what is effectively a base station for the W-CDMA / UMTS 3G cellular system. OQPSK Offset Quadrature Phase Shift Keying. A form of quadrature phase shift keying where the quadrature (Q) component of the signal is offset from the in-phase (I) component by half a symbol period. As a result the amplitude does not cross zero, and this reduces the peak to average ratio. This has advantages for power amplifiers because it reduces the peak to average ratio and as a result it is used in the reverse link for CDMA transmissions. Orthogonality This is a property of codes that can be used as spreading codes for direct sequence spread spectrum (DSSS) transmissions. Codes are said to be orthogonal if they sum to zero over a period of time. Orthogonal codes are used for DSSS transmissions because they do not interfere with one another. Packet Switched Data
  10. 10. Data transmitted from multiple users in individually addressed discrete packets. By using packet data, channels can be used for transmissions from multiple users, thereby improving efficiency. Paging Channel The channel used in GSM and CDMA that is used by the base station to transmit a message to a mobile to indicate that there is an incoming message. The mobile monitors this channel while it remains "idle". PDC Pacific, or Personal Digital Cellular. The TDMA system based on NA-TDMA that is used exclusively in Japan. PDE Position Determining Entity. The area with in a cellular network that is used to determine the position of a mobile for applications such as 911 calls. It will be associated with techniques such as A-GPS, AFLT, etc. Pilot Channel. The channel used in CDMA for initial timing and BTS location. PLMN Public Land Mobile Network. The wire side of a communications network. PN Code Pseudo-noise Code. A binary sequence that exhibits random noise-like properties. PN codes or sequences can be distinguished from random sequences because the pseudo-random sequence repeats after a given time, i.e. it exhibits periodicity. PPP Point-to-Point Protocol. A protocol used to connect a computer to the Internet when using a standard dial-up telephone line. PPP is also used when transmitting data in a cellular network. PSK Phase Shift Keying. A form of modulation where the phase of the signal is altered to carry the information to be transmitted. PSTN Public Switched Telephone Network The land line based or wired telephone system. QCELP Qualcomm Code Excited Linear Prediction. A voice encoder scheme that is used in CDMA systems and that was developed by Qualcomm.
  11. 11. QPSK Quadrature Phase Shift Keying. It may also be known as quaternary or quadric-phase phase shift keying and it is a form of phase shift keying modulation that has four states, usually at 0, 90, 180, and 270 degrees. Rake This is a technique used in digital signal processing where the radio receiver is given uses several base-band correlators. The technique uses the fact that a signal will propagate via several paths to a receiver. The signals arriving via different paths will reach the receiver at different times because of the different path lengths. Using the Rake process all the components can be individually processed and then combined to provide improved performance. RAN Radio Access Network. The portion of a mobile phone network that relates to the transmission or radio communications between the terminal device and the network base station. RAT Radio Access Technology. The technology or system used for the cellular system. GSM and UMTS are two different radio access technologies. Reverse link The path from the mobile handset or terminal to the base station. This term is normally associated with cdmaOne (IS-95) and CDMA2000 (IS-2000) networks. RLP Radio Link Protocol. A protocol used over the air interface. RTT Radio Transmission Technology. The transmission technology used, in this context, by a cellular telecommunications system. It is used particularly in the context of CDMA2000 where 1XRTT and 3XRTT are used. RUIM Removable User Identity Module. A card used in CDMA cell phones that stores the information to identify the caller to the network. It is the equivalent of the SIM card used on GSM phones. SIM Subscriber Identity Module. A card commonly used in GSM phones that store data that identifies the caller to the network service provider. It also provides many other functions including the ability to store phone book numbers etc.
  12. 12. SMS Short Message Service. This is a system that enables short text messages of up to 160 characters to be sent and received via the network operator's message centre. It is also possible to send messages from the Internet, using a so-called "SMS gateway" website. It was first introduced on GSM. Soft Handover A form of handover applicable to CDMA networks (including W-CDMA) where the mobile changes its PN spreading code when handing over from one base station to the next while the frequency channel remains the same. Softer Handover A form of handover applicable to CDMA networks where the system hands over from one sector of a base station to another using a different spreading code. As it is less complicated than soft handover it is given the name, softer handover. Spread Spectrum A method of transmitting a radio signal by spreading it over a wide range of frequencies. Direct sequence spread spectrum (DSSS) in the form of CDMA is used as a cellular telecommunications access technology. Another form of spread spectrum transmission is frequency hopping where the signal moves from one frequency to another, remaining in one place for only a short time. TACS Total Access Communications System. This was the first generation analogue system developed by Motorola that was used in the UK and many other countries around the world. TCP/IP Transmission Control Protocol / Internet Protocol. This is a protocol that defines the way in which data is transmitted in a secure manner between networks. It forms the basis for the Internet. TDD Time Division Duplex. A scheme to allow (virtually) simultaneous transmission in both directions. The uplink and downlink transmissions use the same frequency, but are allocated different time slots. TDMA Time Division Multiple Access. A system that that enables multiple users with access to a mobile phone network by allocating them different time slots within a transmission. This scheme is used by GSM, NA-TDMA, and PDC. TD-SCDMA Time Division Synchronous Code Division Multiple Access. A 3G system that originates from China and uses TDD techniques.
  13. 13. TIA Telecommunications Industry Association. A US telecommunications standards body that was responsible for the generation of IS-2000, the standard for the Third Generation CDMA system (CDMA2000). UMTS Universal Mobile Telecommunications System. The 3G follow on system to GSM that is standardized by ETSI under 3GPP. It uses Wideband CDMA (W-CDMA) with a 5 MHz channel bandwidth. Uplink The path from the mobile terminal to the base station. This term is normally associated with GSM and UMTS networks. USIM Universal Subscriber Identity Module. The subscriber identity module used in UMTS phones. UTRAN UMTS Terrestrial Radio Access Network. The air interface (i.e. radio access) portion of UMTS networks as specified within 3GPP. Walsh codes A family of orthogonal codes widely used for CDMA transmissions. They are one of a group of specialized PN (pseudo-noise) codes that have good autocorrelation properties while exhibiting low levels of cross-correlation. WAP Wireless Application Protocol. It is a widely used set of protocols used on wireless devices such as mobile phones and PDAs. It operates much like the hypertext transfer protocol and standardizes the manner in which wireless devices are able to access parts of the Internet, such as e-mail and the Web. W-CDMA Wideband CDMA. The 3G transmission standard used for UMTS, the successor to GSM. It uses DSSS to provide code vision multiple access with a bandwidth of 5 MHz.

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