Wireless Networks - Chapter 10
highly elliptical orbit (HEO) satellite
Satellite that circles the planet in an elliptical orbit, having a high apogee (maximum altitude) and a low perigee (minimum altitude). This type of satellite can provide good coverage at extreme latitudes, such as the polar regions.
medium earth orbit (MEO) satellite
Satellite that orbits the Earth at altitudes of 1,500- 10,000 miles (2,413-16,090 kilometers).
low earth orbit (LEO) satellite
Satellite that orbits the Earth at an altitude of 200-900 miles (321-1,448 kilometers).
geosynchronous earth orbit (GEO) satellites
Satellites stationed at an altitude of 22,282 miles (35,860 kilometers) that match the rotation of the planet and therefore appear to be in a fixed position in the sky with reference to a point on the ground.
Wideband CDMA (W-CDMA)
The 3G digital cellular technology that is a migration from EDGE.
Long Term Evolution (LTE)
A 4G digital packet-switched cellular technology that expands on HSPA+ beyond two spatially multiplexed channels, uses OFDM modulation, and also uses 20-MHz-wide channels to achieve data rates of up to 100 Mbps.
3G (third generation)
Digital cellular wireless generation of cellular telephony, with speeds up to 2 Mbps.
orthogonal frequency division multiple access (OFDMA)
A method based on OFDM that assigns groups of subcarriers to different users.
8-PSK
A modulation technique in which the phase of the carrier is shifted in 45-degree increments and 4 bits can be transmitted per phase change.
5G (fifth generation)
A new cellular standard currently under development. 5G is currently expected to be ratified in 2018 and the technology does not yet have an acronym like LTE, which is another designation for 4G.
High-Speed Downlink Packet Access (HSDPA)
A packet-switched digital transmission cellular technology that uses 5 MHz W-CDMA (wideband CDMA) channels together with adaptive modulation, MIMO, and hybrid automatic repeat request (HARQ) to achieve data rates between 8 and 10 Mbps.
LTE Advanced
A proposed standard for broadband cellular communications that expands on LTE by allowing carriers to combine up to five 20-MHz-wide OFDM channels to achieve data rates of up to 1 Gbps.
2.5 Generation (2.5G)
An interim technology stage between 2G and 3G digital cellular networks in which data is transmitted using packet-switched technology.
handoff
In cellular technology, the process of a cell taking over an ongoing call from another cell, as the user moves about within his or her home area's cellular coverage area.
plain old telephone system (POTS)
See public switched telephone network.
4G (fourth generation)
The latest active standard for cellular communications, currently deployed or being deployed by cellular carriers worldwide, also commonly marketed by carriers as LTE. According to the ITU, only LTE Advanced qualifies as "true 4G" cellular, but the term 4G can be used if WiMAX and HSPA+ are included in the definition as well.
Voice over LTE (VoLTE)
VoLTE enables carriers to move from circuit-switched voice and packet-switched data to a totally IP-based network, carrying both digitized voice encapsulated in IP datagrams, as well as data.
Enhanced Data rates for GSM Evolution (EDGE)
A 2.5G digital cellular network technology that boosts GPRS transmissions.
CDMA2000 1xRTT
A 2.5G digital cellular network technology that is a migration from CDMA. ("1xRTT" stands for "1-times Radio Transmission Technology.")
general packet radio service (GPRS)
A 2.5G network technology that can transmit at up to 114 Kbps.
3rd Generation Partnership Project (3GPP)
A group of six standards organizations from Asia, Europe, and North America that proposed standards for GSM, GPRS/EDGE, HSDPA, HSPA+, and LTE.
control channel
A special frequency that cellular phones use for communication with a base station.
HSPA+
Also called "evolved HSPA," a technical cellular standard that provides theoretical data rates of up to 168 Mbps (realistically, around 42 Mbps) by combining two HSDPA transmitters, MIMO, and 64 QAM modulation.
roaming
The automatic transfer of the RF signal when moving from one cellular network to another network.
cell
The coverage section of one transmission tower in a mobile network.
Global Systems for Mobile Communications (GSM)
One of three multiple-access cellular technologies that make up the 2G digital cellular system; it uses a combination of FDMA and TDMA.
SIM (Subscriber Identity Module) card
Small electronic cards that are used to associate a phone with a user's account.
cognitive radio
Software-controlled radio that can adapt to the environment by changing frequency channels, bandwidth, modulation, and encoding, depending on the RF environment. These RF characteristics can also be preconfigured by the carriers.
CDMA2000 1xEVDV
The 3G digital cellular technology that is a migration from CDMA2000 1xEVDO.
CDMA2000 1xEVDO
The 3G digital cellular technology that is a migration from CDMA2000 1xRTT.
mobile telecommunications switching office (MTSO)
The connection between a cellular network and wired telephones.
1G (first generation)
The first generation of wireless cellular telephony, which transmitted data at up to at 9.6 Kbps using analog circuit-switched transmission technology.
2G (second generation)
The second generation of cellular telephony, which uses circuit-switched digital transmission technology.
Advanced Mobile Phone Service (AMPS)
The standard used for 1G analog cellular transmissions, based on FDMA. 1G is often simply called AMPS.
single-carrier FDMA (SC-FDMA)
The technology used in LTE for mobile phones to communicate back to the tower transceivers. SC-FDMA assigns a single subcarrier to the same OFDM uplink stream to each mobile user communicating with the same tower.
public switched telephone network (PSTN)
The wired telephone network. Sometimes referred to as the plain old telephone system (POTS).
