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Wireless Technology Terms Glossary and Dictionary [H-M]

HAAT: Height Above Average Terrain
Height Above Average Terrain (HAAT) is a measure of an antenna's height above average terrain. This value is used by the FCC in determining compliance with height limitations and transmitting powers for high sites.

Half rate
Half rate is a term used in voice codecs in a communications system. Most frame formats are designed to accommodate full and half-rate channels, with the intention of implementing half-rate coding as the technology permits to double system capacity. The half rate codec uses only half of the time-slots in the frame.

Hamming code
Hamming code is a well known simple class of block codes capable of detecting up to two errors and correcting one. Although not particularly powerful, they are one of the "perfect" codes in that its standard array has all of the error patterns that can exist for single errors.

Hand Off (Handoff)
Hand Off (handoff) is the process of transferring a call in progress from the current base station to another without interruption as the user moves out of range of the current base station.

Hand Over
Hand Over refers to the passing of a call signal from one base station to the next as the user moves out of range or the network software re-routes the call.

HARQ: Hybrid Automatic Repeat reQuest
Hybrid Automatic Repeat reQuest (HARQ or Hybrid ARQ) is a sheme wherein information blocks are encoded for partial error correction at receiver and additional, uncorrected errors are retransmitted.

Hard Hand Off
Hard Hand Off, used in CDMA systems, describes a hand-off involving a frequency change. The hard hand-off is a break before make hand-off just like in other wireless systems and must be used where the current and hand-off candidate base stations do not use the same RF channel. See also soft hand-off.

Hata Model
Hata Model, also known as the Okamura-Hata model, is used to predict signal strength levels in land-mobile systems.

HCI: Host Controller Interface
A geosynchronous orbit has the same orbital period as the sidereal rotation period of the Earth. It has a semi-major axis of 42,164 km.

HDML: Handheld Device Markup Language
Handheld Device Markup Language(HDML) Specifications allow Internet access from wireless devices such as handheld personal computers and smart phones. This language is derived from hypertext markup language (HTML).

HDTP: Handheld Device Transport Protocol
Handheld Device Transport Protocol (HDTP) is optimized for HDML. It presents the HDML to the HDML interpreter in an appropriate format.

Hertz(Hz) is the measure of frequency which means cycles per second.

HHO: Hard Hand-Off
Hard Hand Off, used in CDMA systems, describes a hand-off involving a frequency change. The hard hand-off is a break before make hand-off just like in other wireless systems and must be used where the current and hand-off candidate base stations do not use the same RF channel. See also soft hand-off.

High-gain Antenna
High-gain Antenna is a type of antenna that significantly increases signal strength. High-gain antennas are necessary for long-range wireless networks.

Hidden Node Problem
The hidden node problem occurs in the wireless networking when a node is visible from a wireless hub, but not from other nodes communicating with said hub. This leads to difficulties in media access control. Hidden nodes in a wireless network refer to nodes which are out of range of other nodes or a collection for nodes. Take a physical star topology with an Access Point with many nodes surrounding it in a circular fashion; each node is within the communication range of the Access Point, however, not each node can communicate with each other.

HLR: home location register
Home Location Register (HLR) is a database residing in a local wireless network that checks the identity of a local subscriber. HLR contains information about subscribers to a mobile network and registers subscribers for a particular service provider. The HLR stores "permanent" subscribers' information (rather than temporary subscribers' data, which a VLR manages), including the service profile, the location information, and the activity status of the mobile user.

HomePNA is a networking standard that uses standard telephone wiring. HomePNA is primarily useful for bridging wireless networks across obstacles (like brick walls) that block radio waves. HomePNA 2.0 runs at 10 Mbps, and the just-defined HomePNA 3.0 runs at 128 Mbps.

HomeRF is a networking standard for home wireless communication, which is a competitor to Wi-Fi that integrates voice, data, and streaming media into a single wireless signal.

Hot spot or hotspot
Hot spot (hotspot) is an area, such as a hotel, restaurant or airport, that offers Wi-Fi access, either free or for a fee.

HPSK: Hybrid Phase Shift Keying
Hybrid Phase Shift Keying (HPSK), also known as Orthogonal Complex Quadrature Phase Shift Keying (OCQPSK), is the spreading technique used in the reverse link of 3G systems to reduce the peak-to-average ratio of the signal by reducing zero crossings and 0 degree phase transitions.

HR/DSSS PHY: High Rate / Direct Sequence Spread Spectrum Physical Layer
High Rate/Direct Sequence Spread Spectrum Physical Layer (HR/DSSS PHY) is the enhanced physical layer defined by IEEE 802.11b which supports data transfer at up to 11Mbps. Unlike the earlier versions of IEEE 802.11 which supported data rates of up to 2Mbps, HR/DSSS uses complementary code keying which divides the chip stream into a number of 8-bit code symbols.

HRPD: High Rate Packet Data
High Rate Packet Data (HRPD), also known as TIA/EIA IS-856 or 1xEV-DO, is a packet data protocol in the 3G mobile communicaitons network based on CDMA2000.

HSCSD: High Speed Circuit Switched Data
High Speed Circuit Switched Data (HSCSD) is a circuit-linked technology for higher transmission speeds -- up to 57 kilobits per second -- primarily in GSM systems.

HSDPA: High-Speed Downlink Packet Access
High-Speed Downlink Packet Access (HSDPA), also called 3.5G (or "3½G"), is a new mobile telephony protocol. High Speed Downlink Packet Access (HSDPA) is a packet-based data service in W-CDMA downlink with data transmission up to 8-10 Mbit/s (and 20 Mbit/s for MIMO systems) over a 5MHz bandwidth in WCDMA downlink. HSDPA implementations include Adaptive Modulation and Coding (AMC), Multiple-Input Multiple-Output (MIMO), Hybrid Automatic Request (HARQ), fast scheduling, fast cell search, and advanced receiver design.

HS-DPCCH: High-Speed Dedicated Physical Control Channel
High Speed Dedicated Physical Control Channel (HS-DPCCH) was introduced in the 3GPP release 5 of WCDMA as a new uplink code channel for control purposes. Besides being the 3rd uplink code channel, the HSDPCCH is not continuously transmitted and is not necessarily time aligned with the other WCDMA uplink channels. As a result, varying power relations to the dedicated uplink channels (DPCCH and DPDCH) are obtained.

HS-PDSCH: High-Speed Physical Downlink Shared Channel
High-Speed Physical Downlink Shared Channel (HS-PDSCH) is channel added to UMTS to increase downlink data rates that is defined in Release 5 of the UMTS specifications and is part of HSDPA. An HS-PDSCH may use QPSK or 16QAM modulation symbols. In the figure above, M is the number of bits per modulation symbols i.e. M=2 for QPSK and M=4 for 16QAM.

HS-DSCH: High-Speed Downlink Shared Channel
High-Speed Downlink Shared Channel (HS-DSCH), a channel added to UMTS to increase downlink data rates that is defined in Release 5 of the UMTS specifications, is a transport channel shared among all users that are using HSPDA for their interactive/background radio access bearer. HS-DSCH can be mapped onto one or several physical channels (also known as codes) all using spreading factor 16.

HSPA: High Speed Packet Access
High-Speed Downlink Packet Access (HSDPA), specified in 3GPP Release 5, extends WCDMA with additional transport and control channels, such as the high-speed downlink shared channel (HS-DSCH), which provides enhanced supports for interactive, background and, to some extent, streaming services.

HS-SCCH: High-Speed Shared Control Channel
High-Speed Shared Control Channel (HS-SCCH) is a channel added to UMTS to increase downlink data rates that is defined in Release 5 of the UMTS specifications and is part of HSDPA.

HSS: Home Subscriber Service
Home Subscriber Service (HSS), a key component in the IP Multimedia Subsystem (IMS), refers to a system including the master user database and software that supports IMS network entities that handle calls and sessions. HSS contains user profiles, performs authentication and authorization of the user, and can provide information about the physical location of user. HSS is similar to the GSM Home Location Register. The entities that communicate with the HSS are the application server (AS) that hosts and executes services in the IMS environment, and the Call State Control Function servers (CSCF). The User Profile contains information about the current user when a user is registering on the network. The S-CSCF will receive the profile in a User-data Attribute Value Pair (AVP) format.

HSUPA: High-Speed Uplink Packet Access
High-Speed Uplink Packet Access (HSUPA) is a data access protocol for mobile phone networks with extremely high upload speeds of up to 5.8 Mbit/s. Similar to HSDPA (High-Speed Downlink Packet Access), HSUPA is considered 3.75G or sometimes 4G.

HERTZ (Hz) is a measurement of frequency in cycles per second. One Hertz is one cycle per second.

IBSS: Independent Basic Service Set
Independent Basic Service Set (IBSS), also known as an ad hoc network. It is an 802.11 network comprising a collection of stations that communicate with each other, but not with a network infrastructure. Do not confuse it with Infrastructure BSS.

IBSS: Infrastructure BSS
Infrastructure BSS (IBSS) is an 802.11 network comprising an access point and stations. The access point forwards information to target stations or to a fixed network.

iDEN: Integrated Digital Enhanced Network
Integrated Digital Enhanced Network (iDEN) is a Motorola-enhanced mobile radio network technology that integrates two-way radio, telephone, text messaging, and data transmission into a single network. iDEN wireless handsets are utilized in a variety of work environments ranging from manufacturing floors to executive conference rooms as well as mobile sales forces.

IF: Intermediate Frequency
Intermediate Frequency (IF) is a frequency to which a carrier frequency is shifted as an intermediate step in transmission or reception. Intermediate electromagnetic frequencies is generated by a superheterodyne radio receiver.

IMSEI: International Mobile Station Equipment Identity
International Mobile Station Equipment Identity (IMSEI) is an identification number assigned to GSM mobile stations that uniquely identifies each one. It is a 15-digit serial number that contains a type approval code, final assembly code and serial number.

IMEI: International Mobile Equipment Identity
The International Mobile Equipment Identity (IMEI) is 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 dialling 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.

I-Mode or iMode
I-Mode, also known as iMode, is a popular wireless Internet service 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.

IMPI: IP Multimedia Private Identity
IP Multimedia Private Identity (IMPI) is one of the two identities used by an IP Multimedia Subsystem (IMS). The other one is the IP Multimedia Public Identity (IMPU). Both are not phone numbers or other series of digits, but URIs, that can be digits (a tel-uri, like tel:+1-555-123-4567) or alphanumeric identifiers (a sip-uri, like The IMPI is unique to the phone, and you can have multiple IMPU per IMPI (often a tel-uri and a sip-uri). The IMPU can also be shared with another phone, so both can be reached with the same identity (for example, a single phone-number for an entire family).

IMPU: IP Multimedia Public Identity
IP Multimedia Public Identity (IMPU) is one of the two identities used by an IP Multimedia Subsystem (IMS). The other one is the IP Multimedia Private Identity (IMPI). Both are not phone numbers or other series of digits, but URIs, that can be digits (a tel-uri, like tel:+1-555-123-4567) or alphanumeric identifiers (a sip-uri, like The IMPI is unique to the phone, and you can have multiple IMPU per IMPI (often a tel-uri and a sip-uri). The IMPU can also be shared with another phone, so both can be reached with the same identity (for example, a single phone-number for an entire family).

IMS: IP Multimedia Subsystem
The IP Multimedia Subsystem (IMS) is a standardised Next Generation Networking (NGN) architecture for telecom operators that want to provide mobile and fixed multimedia services. It uses a Voice-over-IP (VoIP) implementation based on a 3GPP standardised implementation of SIP, and runs over the standard Internet Protocol (IP). Existing phone systems (both packet-switched and circuit-switched) are supported.

IMS-MGW: IP Multimedia Subsystem Media Gateway
IP Multimedia Subsystem Media Gateway (IMS-MGW), a component in the IP Multimedia Subsystem (IMS) 3G architecture, can terminate bearer channels from a switched circuit network and media streams from a packet network. It can support media conversion, bearer control, and payload processing (e.g., using codecs, echo cancellers, or conference bridges).

IM-HSS: IP Multimedia - Home Subscriber Service
The IP Multimedia - Home Subscriber Service (IM-HSS), also known as HSS, is the IP Multimedia Subsystem (IMS) service and user data repository. It plays a key role in provisioning, service creation, enabling subscriber data, and managing control, roaming and interconnection. The IM-HSS: (1) Supports IMS level authentication and authorization; (2) Maintains IMS subscriber profile(s) independent of access types; (3) Maintains service-specific data; (4) Keeps track of currently assigned S-CSCF and (5) Supports CSCF and AS access.

IMSI: International Mobile Station Identity
International Mobile Station Identity (IMSI) is a unique 15-digit number assigned to a mobile station at the time of service subscription. It contains a mobile country code, a mobile network code, mobile subscriber identification number, and a national mobile subscriber identity. The MS sends the IMSI to a BTS for identification of the MS in the GSM network. The BTS looks for the IMSI in the HLR.

IMSI: International Mobile Subscriber Identity
International Mobile Subscriber Identity (IMSI) is a unique number that is associated with all GSM and Universal Mobile Telecommunications System (UMTS) network mobile phone users. The number is stored in the Subscriber Identity Module (SIM). It is sent by the mobile phone to the network and is also used to acquire other details of the mobile in the Home Location Register (HLR) or as locally copied in the Visitor Location Register. In order to avoid the subscriber being identified and tracked by eavesdroppers on the radio interface, the IMSI is sent as rarely as possible and a randomly generated TMSI is sent instead.

IMT-2000: International Mobile Telecommunication 2000
International Mobile Telecommunication 2000 (IMT-2000) is a group of technologies defined by ITU-T for the third generation mobile telephony. It can also be applied to mobile telephone standards that meet a number of requirements in terms of transmission speed and other factors.

IMTA: International Mobile Telecommunications Association
International Mobile Telecommunications Association (IMTA) is a trade group serving specialized mobile radio and public access mobile radio carriers around the world.

IMTS: Improved Mobile Telephone Service
Improved Mobile Telephone Service (IMTS) is the commercial form of mobile telephone service preceding cellular that allowed users to place and receive their own calls through the use of a dial or keypad on the telephone.

IN: Intelligent Network
Intelligent Network (IN) often referred to as the Advanced Intelligent Network, this is a network of equipment, software and protocols used to implement features on the network and support switching and control functions.

InFLEXion is the narrowband PCS technology developed by Motorola Inc. that allows for voice paging.

Infrared is the electromagnetic waves whose frequency range is above that of microwaves, but below that of the visible spectrum.

Interferance is the effect that occurs when undesired signals inhibits or degrades the reception of a desired signal.

IR: Incremental Redundancy
Incremental redundancy (IR) is the feature used by EDGE (EGPRS) systems to get maximum performance out of the available bandwidth. It works by first sending only the minimum amount of redundant data, i.e. in most cases, no redundant data. If the data is not decoded properly, the system will resend the same data using a different puncture or coding scheme, increasing the amount of redundant data and the likelihood of recovering from the errors. If data is retransmitted using a different puncture or coding scheme, it is then recombined with the first transmission to increase redundancy.

IRC: Infrared communication
InfraRed Communication (IRC), is employed in short-range communications among computer peripherals and personal digital assistants. These devices usually conform to standards published by IrDA, the Infrared Data Association. Remote controls and IrDA devices use infrared light-emitting diodes (LEDs) to emit infrared radiation which is focused by a plastic lens into a narrow beam. The beam is modulated, i.e. switched on and off, to encode the data. The receiver uses a silicon photodiode to convert the infrared radiation to an electric current. It responds only to the rapidly pulsing signal created by the transmitter, and filters out slowly changing infrared radiation from ambient light. Infrared communications are useful for indoor use in areas of high population density. IR does not penetrate walls and so does not interfere with other devices in adjoining rooms.

IrDA: Infrared Data Association
Infrared Data Association (IrDA) is an industry organization that creates standards for hardware and software used in infrared communications. Information is transferred via rays of light, as opposed to radio waves. Most TV remote controls use infrared. IrDA standards have been implemented on various computer platforms and, more recently, have become available for many embedded applications.

IrOBEX: Infrared OBject Exchange
Infrared OBject EXchange (IrOBEX) or OBEX) is a communications protocol that facilitates the exchange of binary objects between devices. It is maintained by the Infrared Data Association but has also been adopted by the Bluetooth Special Interest Group and the SyncML wing of the OMA. One of OBEX's earliest popular applications was in the Palm III personal digital assistant. This PDA and its many successors use OBEX to exchange business cards, data, even applications.

IS-136, replacing IS-54 of the original tDMA standard, is the second-generation (2G) mobile phone systems used in the D-AMPS. IS-136 uses Time Division Multiple Access(TDMA) as an air interface.

IS-2000, also known as EIA Interim Standard 2000, is a standard for current CDMA systems providing a migration path to 3G services.

IS-41, also known as ANSI-41 since it is a standard defined by ANSI, is a specification for identifying and authenticating users, and routing calls on mobile phone networks based on MPS (analog), IS-136 (TDMA) and CDMA technologies. The standard also defines how users are identified, and calls are routed when roaming across different networks. GSM and WCDMA networks use a different standard known as MAP for the same purpose.

IS-54, an EIA Interim Standard for U.S. Digital Cellular (USDC), is the original TDMA digital standard implemented in 1992. This standard was the first to permit the use digital channels in AMPS systems. It used digital traffic channels but retained the use of analog control channels. This standard was replaced by the IS-136 digital standard in 1996.

The IS-634 interface is a standard defined by TIA/EIA that defines the messaging interface between a TDMA Base Station (BS) and a Mobile Switching Center (MSC). This interface uses the services provided by Connection Oriented SCCP for its transport layer. IS-634 is deployed worldwide in the cdmaOne mobile wireless networks.

IS-661 is a North American standard for 1.9 GHz wireless spread spectrum radio-frequency access technology developed by Omnipoint Corp. IS-661, for which Omnipoint was awarded a pioneer's preference license for the New York City market, is based on a composite of code division multiple access and time division multiple access technologies. The company says IS-661 reduces infrastructure costs and allows higher data speeds than mainstream GSM or TDMA platforms.

Interim Standard 95 (IS-95), is the first CDMA-based digital cellular standard pioneered by Qualcomm. The brand name for IS-95 is cdmaOne. IS-95 is also known as TIA-EIA-95. It is a 2G mobile telecommunications standard that uses CDMA, a multiple access scheme for digital radio, to send voice, data and signaling data (such as a dialed telephone number) between mobile telephones and cell sites.

IS-95a, an EIA Interim Standard 95, is the original digital mobile telephony standard based on CDMA technology. It is applied in the cdmaOne mobile network.

IS-95b is an upgraded version of IS-95a for the cdmaOne mobile network that increases the maximum data rate to 115.2 kb/s.

ISI: Inter-Symbol Interference
Inter-Symbol Interference (ISI) is an interference effect where energy from prior symbols in a bit stream is present in later symbols. ISI is normally caused by filtering of the data streams.

ISIM: IP Multimedia Services Identity Module
IP Multimedia Services Identity Module (ISIM) is an application running on a Universal Integrated Circuit Card (UICC) smart card in a 3G mobile telephone in the IP Multimedia Subsystem (IMS). It contains parameters for identifying and authenticating the user to the IMS. The ISIM application can co-exist with SIM and USIM on the same UICC making it possible to use the same smart card in both GSM networks and earlier releases of UMTS.

iTAP, also known as T9 TM text input, is a application installed on wireless phones and handheld devices that allows you to type messages with just one key press per letter using the keypad. It is a much easier text input method than the traditional multi-tapping.

ITU: International Telecommunications Union
International Telecommunications Union (ITU) is a United Nations agency that deals with telecommunications issues.

IWF: Interworking Function
Interworking Function (IWF) is a technique for interfacing data between a wireless system and the telephone network. It usually involves the use of modems or data terminal adapters to convert the data transmitted over the air interface and mobile network to a format that can be recognized and carried by the public telecommunications network.

J2ME: Java 2 Platform, Micro Edition
Java 2 Platform Micro Edition (J2ME) is a technology that allows developers to use the Java programming language to create applications for mobile wireless devices.

Jamming refers to the interference with the air radio transmission. It may be used by people who is trying to disturb the receiver from receiving the radio signal at a target frequency.

JavaPhone is a Java API specification controlling contacts, power management, call control, and phone book management. It is intended specifically for the programming requirements of mobile phones.

JTACS or J-TAGS: Japanese Total Access Communication System
Japanese Total Access Communication System (JTAGS) is a 1G technology deployed in Japan based on the European TACS system. JTAGS is operating in the 900-MHz band.

JTAPI: Java Telephony API
The Java Telephony API (JTAPI) is an extensible API that offers an interface to all call control services. The services include those needed in a consumer device up to those of enterprise call centers. JTAPI is part of the JavaPhone API.

Ka-Band refers to the bandwidth of electromagnetic wave between 33 GHz to 36 GHz, which is primarily used in satellites operating at 30 GHz uplink and 20 GHz downlink for mobile voice communications.

Key Pulse Signal
Key-pulse signal is the first signal in an multifrequency outpulsing format, which is a control signal used to prepare the remote customer installation to receive digits.

KHz: KiloHertz
One kHz (KiloHertz) is equal to 1,000 Hertz, which is a measurement of frequency.

kpbs: Kilobits per second
kpbs (Kilobits per second) is a measurement of data rate, for example, data services for 2G operates at maximum speed of 9.6kbps.

Ku-Band refers to the bandwidth of electromagnetic wave between 12 GHz to 14 GHz, which is primarily used in satellites operating at 14 GHz uplink and 11 GHz downlink in supporting braodband TV and Direct Broadcast Satellite (DBS) system (DSS).

L2CAP: Logical Link Control and Adaptation Protocol
Logical Link Control and Adaptation Protocol, typically short as L2CAP, is used within the Bluetooth protocol stack at the data link layer. It passes packets to either the Host Controller Interface (HCI) or on a hostless system, directly to the Link Manager.

LAI: Location Area Identity
Location Area Identity (LAI) is the information carried in the SIM of GSM handsets that identify the subscriber's home area. This is used for billing and sub-net operation purposes.

LASCDMA: Large Area Synchronized Code Division Multiple Access
Large Area Synchronized Code Division Multiple Access (LASCDMA) is a technology developed by LinkAir that offers a higher spectral efficiency and moving speed for better mobile-application support.Also, its asymmetric traffic, higher throughput, and smaller delay provide improved IP support. Currently, LAS-CDMA is being considered as phase 2 of the 1xEV standards. A LAS-CDMA TDD variant is compatible with systems such as TD-SCDMA.

LDPC code: Low-Density-Parity-Check code
A low-density parity-check code (LDPC code) is an error-correcting code and a method of transmitting a message over a noisy transmission channel. While LDPC and other error correcting codes cannot guarantee perfect transmission, the probability of lost information can be made as small as desired. LDPC was the first code to allow data transmission rates close to the theoretical maximum, the Shannon Limit.

LEAP: Lightweight Extensible Authentication Protocol
Lightweight Extensible Authentication Protocol (LEAP), also known as Cisco-Wireless EAP, is a Cisco security technology that builds on Wi-Fi's WEP encryption. Basically, it changes the WEP key dynamically during a session to make it less likely that a snooper will be able to derive the key. LEAP provides username/password-based authentication between a wireless client and a RADIUS server like Cisco ACS or Interlink AAA. LEAP is one of several protocols used with the IEEE 802.1X standard for LAN port access control.

Lee's model
Lee's model is a slope-intercept propagation prediction model developed at Bell Laboratories and popularized by William Lee. The model assumes an initial condition at a short distance from a base station and uses that as one end of a slope intercept model to predict path loss between a base station and a mobile unit.

LEO: Low Earth Orbit
Low Earth Orbit (LEO) is the orbit between 700 and 2,000 kilometers above the Earth for Mobile communications satellite.

Link budget
Link budget is a calculation involving the gain and loss factors associated with the antennas, transmitters, transmission lines and propagation environment used to determine the maximum distance at which a transmitter and receiver can successfully operate.

LMDS: Local Multipoint Distribution System
Local multipoint distribution system (LMDS) is the broadband wireless technology used to deliver voice, data, Internet, and video services in the 25-GHz and higher spectrum (depending on licensing). As a result of the propagation characteristics of signals in this frequency range, LMDS systems use a cellular-like network architecture though services provided are fixed, not mobile. In the United States, 1.3 MHz of bandwidth (27.5 B 28.35 GHz, 29.1 B 29.25 GHz, 31.075 B 31.225 GHz, 31 B 31.075 GHz, and 31.225 B 31.3 GHz) has been allocated for LMDS to deliver broadband services in a point-to-point or point-to-multipoint configuration to residential and commercial customers. This tutorial details the underlying technology inherent in offering voice, data, Internet, and video services over LMDS through integration with the wireline environment.

LMP: Link Manager Protocol
Link Manager Protocol (LMP) is a data link layer protocol in the Bluetooth protocol stack. LMP carries out link setup, authentication, link configuration and other protocols. It discovers other remote Link Manager (LM) and communicates with them via the Link Manager Protocol (LMP). To perform its service provider role, the LM uses the services of the underlying Link Controller (LC).

LNA: Low Noise Amplifier
Low Noise Amplifier (LNA) is a receiving preamplifier having very low internal noise characteristics placed very near the antenna of a receiver to capture the C/N before it can be further degraded by noise in the receiving system.

LNP: Local Number Portability
Local Number Portability (LNP) is the capability that allows wireless customers to switch carriers but retain the same phone number. Wireless portability is expected to become a reality by the end of 2003.

Location registration
Location registration is one of several computer databases used to maintain location and other information on mobile subscribers. See HLR and VLR.

Location Server
Location Server allows end users to connect real-time location information from mobile service operator with mapping and routing information. Location server enables mobile service providers to provide their end-users with personalized contents that are location-dependent.

Logic Channel
Logic Channel is a communications channel derived from a physical channel. A physical channel, i.e. RF channel, typically carries a data stream that contains several logical channels. These usually include multiple control and traffic channels.

LOS: Line of Sight
Line of Sight (LOS) describes an unobstructed radio path or link between the transmitting and receiving antennas of a communications system. The opposite to LOS is NLOS, or Non Line of Sight.

LOS: Loss of Signal
Loss of signal (LOS) is a condition where the received signal drops below threshold due to a terrain obstruction or other phenomenon increasing the link budget loss beyond design parameters.

LPA: Linear Power Amplifier
Linear Power Amplifier (LPA) is the final amplification stage in a multicarrier transmitter that has been designed and optimized to produce a linear response. By operating in the linear mode, the amplifier reduces the non-linear effects that produce intermodulation products and side-lobe spectra that cause adjacent channel interference.

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

LPC: Linear Predictive Coding
Linear Predictive Coding (LPC) is a speech encoding scheme that uses periodic pulses to excite a filter, similar to the way human voice is produced. The code is predictive in that it uses knowledge of past data (represented as vectors) to predict future values in a feed forward manner.

LSB: Least Significant Bit
Least Significant Bit (LSB), in a binary coding scheme, is the bit having the least numerical value. Analogous to the units position in a decimal number.

Lu is one of four interfaces connecting the UTRAN internally or externally to other functional entities. The other three are Uu, lub and lur. The lu interface is an external interface that connects the RNC to the Core Network (CN). Lu is the standardized interface between a Radio Network Controller Network and Packet Subsystem (e.g. RNC-3GSGSN).

Lub is one of four interfaces connecting the UTRAN internally or externally to other functional entities. The other three are Uu, lu and lur. The lub is an internal interface connecting the RNC with the Node B. And at last there is the lur interface which is an internal interface most of the time, but can, exceptionally be an external interface too for some network architectures. Lub is the interface between a Base Station and Radio NetworkController.

Lur is one of four interfaces connecting the UTRAN internally or externally to other functional entities. The other three are lu, Uu, and lub. The lur interface which is an internal interface most of the time, but can, exceptionally be an external interface for some network architectures, too. The lur connects two RNCs with each other.

MAC address
MAC address (Media Access Control address) is the address associated with every hardware device on the network. Every wireless 802.11 device has its own specific MAC 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.

MACRO Cell, also known as macrocell, is a large cell in a wireless system capable of covering a large physical area. Macrocells are used in rural areas and other areas where subscriber or traffic densities are low.

MAHO: Mobile Assisted Handoff
Mobile Assisted Handoff (MAHO) is a handoff technique involving feedback from the mobile station as part of the handoff process. The feedback is usually in the form of signal level and quality measurements on the downlink and signal level measurements from neighbor cells.

MAI: Multiple Access Interference
Multiple Access Interference (MAI) is a type of interference caused by multiple cellular users who are using the same frequency allocation at the same time. In both 2G and 3G moble networking, each user is then given a pair of frequencies (uplink and downlink) and a time slot during a frame. Different users can use the same frequency in the same cell except that they must transmit at different times. This multiple-access interference can present a significant problem if the power level of the desired signal is significantly lower (due to distance) than the power level of the interfering user.

MANET: Mobile Ad Hoc Network
Mobile Ad Hoc Network (MANET) refers to a type of mobile network in which each node has the ability to act as a router, permitting adaptable multihop communications. The establishment and maintenance of these routes, however, is severely affected by the stochastic nature of wireless communications, making it diffcult to implement such nets in practice.

MAP: Mobile Application Part
The Mobile Application Part (MAP), one of the protocols in the SS7 suite, allows for the implementation of the mobile network (GSM) signaling infrastructure. The premise behind MAP is to connect the distributed switching elements, called mobile switching centers (MSCs), with a master database, called the Home Location Register (HLR). The HLR dynamically stores the current location and profile of a mobile network subscriber. The HLR is consulted during the processing of an incoming call.

Master Access Point
Master Access Point is the primary access point in a wireless network that uses WDS to extend range. The master access point shares the Internet connection with the rest of the remote, or relay access points, along with all the wireless clients.

Matched filter
Matched filter is the receiver filter with impulse response equal to the timereversed,complex conjugate impulse response of the combined transmitter filter-channel impulse response.

MBMS: Multimedia Broadcast Multicast Service
Multimedia Broadcast Multicast Service (MBMS) is a broadcasting service that can be offered via existing GSM and UMTS cellular networks. The infrastructure offers an option to use an uplink channel for interaction between the service and the user, which is not a straightforward issue in usual broadcast networks, as for example conventional digital television is only a one-way (unidirectional) system. MBMS uses multicast distribution in the core network instead of point-to-point links for each end device.

MBOA: MultiBand OFDM Alliance
MultiBand OFDM Alliance (MBOA) was an industrial association with a focus on the Ultra WideBand wireless communication technologies. The Multi-Band OFDM Alliance and the WiMedia Alliance were merged in 2005, under the name or WiMedia Alliance to align goals more fully.

MBS: Mobile Broadband Systems
Mobile Broadband Systems (MBS) are extensions of the wired B-ISDN system. MBS provides radio coverage restricted to a small area (e.g. sports arena, factory, television studio) and supports communications between MBS mobile terminals and terminals directly connected to the B-ISDN at up to 155 Mbit/s.

MBWA: Mobile Broadband Wireless Access
Mobile Broadband Wireless Access (MBWA), nicknamed as Mobile-Fi, is an IEEE standard defined by the 802.20 group to define the interface that allows the creation of low-cost, always-on, and truly mobile broadband wireless networks. The scope of the MBWA standard consists of the physical (PHY), medium access control (MAC), and logical link control (LLC) layers. The air interface will operate in bands below 3.5 GHz and with a peak data rate of over 1 Mbit/s.

MC-CDMA, also called CDMA2000, typically means the combination of three IS-95 carriers to form one wideband carrier. It is an evolution of IS-95 for third generation systems.

MCD: Mobile Computing Device
Mobile Computing Devices (MCD) are the computer devices such as notebook that can access to the network through mobile access.

Mcps: Mega Chips Per Second
Mega Chips Per Second (Mcps) is a measure of the number of bits (chips) per second in the spreading sequence of direct sequence spreading code.

MDA: Microconnect Distributed Antennae
Microconnect Distributed Antennae (MDA) are small-cell local area (200--300 metre range) transmitter-receivers usually fitted to lampposts and other street furniture in order to provide Wireless LAN, GSM and GPRS connectivity. They are therefore less obtrusive than the usual masts and antennae used for these purposes and meet with less public opposition. Each antenna point contains a 63-65 GHz wireless unit alongside a large memory store providing proxy and cache services.

MDSS: Mobile Data Synchronization Service
Mobile Data Synchronization Service (MDSS) is the ability to synchronize data on client devices with data stored in an enterprise database. A common protocol has been developed that will eventually allow a variety of clients to synchronize with a variety of databases.

MED: Message Entry Device
Message Entry Device (MED) is a device which sends information into a paging network using TDP. This may be any type of device from a hand-held type of unit to a host computer.

MexE: Mobile Station Application Execution Environment
Mobile Station Application Execution Environment (MexE) is a framework to ensure a predictable environment for third-party applications in GSM or UMTS handsets. MExE does this by defining different technology requirements called "classmarks." MExE classmark 1 is based on WAP, classmark 2 on PersonalJava and JavaPhone, and classmark 3 on J2ME CLDC and MIDP. Other classmarks may be defined in the future. MExE specifies additional requirements for all classmarks, for instance, a security environment, capability and content negotiation, a user profile, user interface personalization, management of services and virtual home environment. A handset can support multiple classmarks.

MFN: Multi-Frequency Network
A Multi-Frequency Network (MFN) is a type of radio network that operates several transmitters on a number of different frequencies.

MGCF: Media Gateway Control Function
Media Gateway Control Function (MGCF), a component in the IP Multimedia Subsystem (IMS), communicates with the Call Session Control Function (CSCF) and controls the connections for media channels in an IMS-MGW. It performs protocol conversion between ISDN User Part (ISUP) and the IMS call-control protocols.

MHS: Message Handling System
Message Handling System (MHS) is a general-purpose system used for receiving, storing, and sending messages with a consistent set of protocols to connect to external devices.

MHz: Megahertz
MHz or Megahertz, in which one MHz is equal to one million Hertz, is a measurement of frequency.

Microbrowser is a modified Web browser that allows users to get Internet data on a handheld wireless device

Microcell is a very small cell used in densely populated areas where traffic volume is high. There is no official definition of what cell radius distinguishes a small cell from a microcell.

Microwave is the electromagnetic waves in the frequency range of 1 to 30 GHz. Microwave-based networks are an evolving technology gaining favor due to high bandwidth and relatively low cost.

MIDP: Mobile Information Device Profile
Mobile Information Device Profile (MIDP) is a set of Java APIs that is generally implemented on the Connected Limited Device Configuration (CLDC). It provides a basic J2ME application runtime environment targeted at mobile information devices, such as mobile phones and two-way pagers. The MIDP specification addresses such issues as user interface, persistent storage, networking, and application model.

MIMO: Multiple Input Multiple Output
Multiple Input Multiple Output (MIMO) refers to using multiple antennas in a Wi-Fi device to improve performance and throughput. The MIMO technology takes advantage of a characteristic called multipath, which occurs when a radio transmission starts out at point A and then reflects off or passes through surfaces or objects before arriving, via multiple paths, at point B. MIMO technology uses multiple antennas to collect and organize signals arriving via these paths. The technology is included the 802.11n standard.

MIN: Mobile Identification Number
Mobile Identification Number (MIN) is a unique identification number given to a mobile unit. In most cases, this number is the telephone number of the handset. In the case of analog cellular, the MIN is used to route the call. In most second generation system, the system assigns temporary numbers to the handset to route calls as a security precaution. See also TMSI.

MISO: Multiple Input, Single Output
Multiple Input Single Output (MISO) is a smart antenna technology that uses multiple transmitters and a single receiver on a wireless device to improve the transmission distance. MISO technology can be applied in areas such as Digital TeleVision (DTV), Wireless Local Area Networks (WLANs), Metropolitan Area Networks (MANs), and mobile communications. The implementation of MISO would include multiple antennas at the source, or transmitter, and the destination, or receiver, has only one antenna -- the antennas are combined to minimize errors and optimize data speed. Other forms of smart antenna technology include Multiple Input Multiple Output (MIMO) and Single Input Multiple Output (SIMO).

m-law companding
M-law companding is a type of non-linear (logarithmic) quantizing, companding and encoding techniques for speech signals based on the m-law. This type of companding uses a m factor of 255 and is optimized to provide a good signal-to-quantizing noise ratio over a wide dynamic range.

MLD: Maximum Likelyhood Detection
Maximum Likelyhood Detection (MLD) is an optimal scheme for detecting the spatially multiplexed signals in a mobile network.

MMDS: Multichannel Multipoint Distribution Service
Multichannel multipoint distribution service (MMDS), also known wireless cable, is a wireless telecommunications technology, used for general-purpose broadband networkings or, more commonly, as an alternative method of cable television programming reception. MMDS is used usually in sparsely populated rural areas, where laying cables is not economically viable. The MMDS band uses microwave frequencies from 2 GHz to 3 GHz in range. Reception of MMDS-delivered television signals is done with a special rooftop microwave antenna and a set-top box for the television receiving the signals. The receiver box is very similar in appearance to an analog cable television receiver box.

MMM: Mobile Media Mode
Mobile Media Mode (MMM, also marked as WWW:MMM), is a marketing icon comprising a unifying industry-wide marketing symbol representing web-based mobile products and services.

MMR: Mobile Multihop Relay
Mobile Multihop Relay (MMR) refers to the concept of relaying user data and possibly control information between an MMR base station and an IEEE Standard 802.16 compliant mobile station through one or more relay stations. Licensed spectrum is used for relay. The purpose of enabling relay is to enhance coverage, range, and throughput and possibly capacity of an MMRBS and to enable very low power devices to participate in the network. The adjective "mobile" used here refers to the fact that both mobile subscriber stations and mobile relay stations are supported. It is possible to establish multiple communications paths between the MMR-BS and an MS and to communicate the same user data and/or control/management information through both paths to improve communications reliability.

MMR-BS: MMR Base Station
Mobile Multihop Relay Base Station (MMR-BS) refers to a base station that is compliant with amendments IEEE 802.16j through IEEE 802.16e-2005, which has extended functionality to support MMR as defined in 802.16j. An MMR-BS is fully compliant with IEEE Standard 802.16e-2005 and has been enhanced by amendment IEEE 802.16j to support mobile multihop relay. Mobile multihop relay is supported only for the OFDMA mode of IEEE Standard 802.16e-2005. Relay stations that support a particular MMR-BS are managed by that MMR-BS.

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

MMSE: Minimum Mean Squared Error
Minimum mean-square error (MMSE) relates to an estimator having estimates with the minimum mean squared error possible. MMSE estimators are commonly described as optimal.

Mobile Data service
Mobile data service is a personal communications service that is expected to provide two-way wireless communication of text, voice messages, and potentially video messages among computers, personal digital assistants, and databases. Mobile data services can be provided by a number of technologies such as cellular, Personal Telecommunications Services, mobile satellite, and Enhanced Specialized Mobile Radio, as well as networks.

Mobile IP
Mobile IP is the key protocol to enable mobile computing and networking, which brings together two of the world's most powerful technologies -- the Internet and mobile communication. In Mobile IP, two IP addresses are provided for each computer: home IP address which is fixed and care-of IP address which is changing as the computer moves. When the mobile moves to a new location, it must send its new address to an agent at home so that the agent can tunnel all communications to its new address timely.

Mobile phone network
Mobile phone network is a network of cells. Each cell is served by a radio base station from where calls are forwarded to and received from your mobile phone by wireless radio signals.

Mobile Satellite
Mobile Satellite is a personal communications service that is anticipated to provide two-way voice and data communications using satellites, handheld phones, and wireless modems incorporated into devices such as notebook computers. It is expected that Mobile Satellite services will offer enhanced features such as call waiting and voice mail. Geographic service coverage is anticipated to be larger than most PCS services and may be worldwide.

Mobile Station
Mobile Station (MS) refers generically to any mobile device, such as a mobile handset or computer, that is used to access network services. GPRS networks support three classes of mobile station, which describe the type of operation supported within the GPRS and the GSM mobile wireless networks. For example, a Class A MS supports simultaneous operation of GPRS and GSM services.

Mobile WiMAX
Mobile WiMax refers to the technologies defined in the IEEE 802.16e (formally known as 802.16-2005), which addresses mobility of wireless broadband (WiMax). 802.16e, based on an existing WiMax standard 802.16a, adds WiMax mobility in the 2 to 6 GHz licensed bands. provides an improvement on the modulation schemes stipulated in the original (fixed) WiMAX standard. Mobile WiMax allows for fixed wireless and mobile Non Line of Sight (NLOS) applications primarily by enhancing the OFDMA (Orthogonal Frequency Division Multiple Access).

Modulate refers to varying the amplitude, frequency or phase of a radio signal in order to transmit information.

Modulation refers to carring information on a signal by varying one or more of the signal's basic characteristics -- frequency, amplitude and phase. Different modulation carries the information as the change from the immediately preceding state rather than the absolute state.

MOS: Mean Opinion Score
Mean Opinion Score (MOS) is a statistical rating and scoring technique used to rate the performance of telephone connections by users.

MPE: Multi-Pulse Excited
Multi-Pulse Excited (MPE) is a multi-pulse process for determining the position and amplitude of sample pulses in a speech codec.

MRFC: Multimedia Resource Function Controller
Multimedia Resource Function Controller (MRFC), a component in the IP Multimedia Subsystem (IMS), is the element responsible for taking SIP requests from the Application Server (AS) and translating them to messages that control the media processing resources residing in the Multimedia Resource Function Processor (MRFP).

MRFP: Multimedia Resource Function Processor
Multimedia Resource Function Processor (MRFP) is a component in the IP Multimedia Subsystem (IMS). The mixing of the various conference participants media streams is performed by the MRF (Media Resource Function) which comprises of the MRFC (Media Resource Function Controller) and the MRFP (Media Resource Function Processor). MRFP is where the actual media processing resources reside.

MRS: Mobile Relay Station
Mobile Relay Station (MRS), a concept in the mobile WiMAX network, is a relay station that is intended to function while in motion. MRS mobility is constrained by the same limits as an Mobile Staton (MS) in IEEE Std 802.16e-2005. An MRS may be installed in a bus or train for use by IEEE Std 802.16-2005 subscribers.

MS: Mobile Station
Mobile Station refers to the customer terminal including hardware and software in a wireless network.

MSA: Metropolitan Statistical Area
Metropolitan Statistical Area (MSA) is a geographic area over which a cellular operator is licensed to provide service. MSAs are groups of counties in metropolitan areas having common financial, commercial and economic ties and were first used to license cellular service in the early '80s. MSAs cross state lines in some instances. MSAs were first used by the Dept.of Commerce to collect economic data.

MSB: Most Significant Bit
Most Significant Bit (MSB), in a binary coding scheme, is the bit having the greatest numerical value. Analogous to the left-most numeric position in a decimal number.

MSC: Mobile Switching Center
Mobile Switching Center (MSC) is the place that provides telephony switching services and controls calls between telephone and data systems. The MSC switches all calls between the mobile and the PSTN and other mobiles.

MSISDN: Mobile Station Integrated Services Digital Number
Mobile Station Integrated Services Digital Number (MSISDN), the mobile equivalent of ISDN, refers to the 15-digit number that is used to refer to a particular mobile station. The ITU-T recommendation E.164 defines the international numbering plan that MSISDN is based on. The acronym MSISDN has a number of different expansions when used to refer to the value: Mobile Subscriber ISDN Number, Mobile Station International Subscriber Directory Number, Mobile Station ISDN Number, amongst other variants.

MSK: Minimum Shift Keying
Minimum Shift Keying (MSK) is a modulation technique using sinusoidal shaped input data pulses to drive the phase modulator. This results in a linear phase change over conventional QPSK, resulting in lower side lobes and less adjacent channel interference performance.

MSO: Multi-Services Operator
Multi-Services Operator (MSO) is a service provider which provides multiple services such as voice (mobile and fixed line), data and vedio.

MSS: Mobile Satellite Service
Mobile satellite services (MSS) refers to the communications satellites network for mobile and portable wireless telephones services. There are three major types of MSS: AMSS (aeronautical MSS), LMSS (land MSS), and MMSS (maritime MSS).

MTA: Message Transfer Agent
Message Transfer Agent (MTA) is the portion of a Message Handling System (MHS) that deals with moving messages within the Message Handling System (MHS).

MTSO: Mobile Telephone Switching Office
Mobile Telephone Switching Office (MTSO), a computer or a switch, is the brains of a cellular system. The MTSO assigns frequencies to each call, reassigns frequencies for hand-offs, interconnects calls with the local and long distance landline telephone companies, compiles billing information, etc. Every cellular system has one or more MTSOs or switches.

Multichannel Multipoint Distribution Service
Multichannel multipoint distribution service is a broadcasting and communications service that operates in the ultra-high frequency (UHF) portion of the radio spectrum between 2.1 and 2.7 GHz. Multichannel multipoint distribution service is also known as wireless cable. It was conceived as a substitute for conventional cable television (TV). However, it also has applications in telephone/fax and data communications.

Multipath is a propagation phenomenon characterized by the arrival of multiple versions of the same signal from different locations shifted in time due to having taken different transmission paths of varying lengths.

Multiple access
Multiple access is the process of allowing multiple radio links or users to address the same radio channel on a coordinated basis. Typical multiple access technologies include FDMA, TDMA, CDMA, and FHMA.