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There are 32 names in this directory beginning with the letter H.
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.

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.

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.

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.

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.

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.

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

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.

HS-DPCCH: High-Speed Dedicated Physical

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-DSCH: High-Speed Downlink Shared Chan

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.

HS-PDSCH: High-Speed Physical Downlink S

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-SCCH: High-Speed Shared Control Chann

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.

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.

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.

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.


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