|
1. |
Acknowledgement: It is the reply from the receiver to the
sender that the data was received successfully. |
|
2. |
Adhoc
network: It’s a type of network without any centralized
control it is also called as basic server set or peer to peer
network. In adhoc network, stations communicate directly with each
other through the SSID. |
|
3. |
AES: Advanced Encryption standard is used to encrypt the
data. It uses 128, 192 and 256 bit keys. |
|
4. |
Authentication: Authentication is a process of identifying the
secure users. In a wireless network a station sends an
authentication frame to another station if it wishes to begin
secure communication. |
|
5. |
Attenuation: A loss of signal strength usually related to the
distance the signal must travel. Radio signal attenuation may be
due to atmospheric conditions, antenna design / positioning,
obstacles, etc. Attenuation is measured in decibels. |
|
6. |
Asynchronous (i.e. Not Synchronous): A form of concurrent
input and output communication transmission with no timing
relationship between the two signals. |
|
7. |
AWGN:
abbreviation for Additive White Gaussian Noise which is having
uniform spectral density over a range of frequencies |
|
8. |
Bandwidth:
It is a measure of the significant spectral content. |
|
9. |
Base
station: A transmitting/receiving station fixed at a location
serving one or more subscriber stations. |
|
10. |
Baseband
signal: A signal which is centered at DC (0 Hz) and
unmodulated. |
|
11. |
Beacon:
To keep the network synchronized access points or stations
broadcast a type of packet called as Beacon. |
|
12. |
BER:
Bit Error Rate (BER) defined as ratio of number of bits in error
by the number of bits transmitted. |
|
13. |
Bit Rate:
The speed at which bits are transmitted on a network, usually
expressed in bits per second. |
|
14. |
Bluetooth:
Bluetooth is one of the wireless personal area network standard
that operates in the 2.4 GHz band and allows the portable personal
devices to communicate within a short range. |
|
15. |
BPSK:
Binary Phase shift keying abbreviated as BPSK is a modulation
technique where the carrier is shifted by 180 degrees in
accordance with a digital bit stream. “0” does not produce a phase
transition where as “1” causes a phase transition to occur. |
|
16. |
Broadband:
Term applied to broad bandwidth more than 1 MHz and supports data
rates greater than 1.5 Mbps. |
|
17. |
BSSID:
Basic server set identifier. A 48 bi t identifier used by all
stations in a BSS in a frame header |
|
18. |
Carrier:
A high frequency signal used to modulate the message signal.
Various parameters of the carrier can be modified such as phase,
amplitude, frequency. |
|
19. |
CCDF:
Complimentary cumulative distribution function. |
|
20. |
CCITT:
Consultant Committee on International Telephone and Telegraph - An
international organization which develops standards and defines
interfaces for telecommunications. |
|
21. |
CCK:
Complimentary Code Keying- A modulation scheme that transforms
data blocks into complex codes and is capable of encoding several
bits per block. |
|
22. |
Chassis:
Chassis refer to the metallic body or frame which provides rugged
and modular packaging for the system. |
|
23. |
Chipset:
A group of integrated circuits (IC’s) that are designed to work as
a single entity. |
|
24. |
Co channel
Interference: Undesired signals with frequency components that
fall within the frequency range of the desired channel.
Interference from a channel that is transmitting in the same
frequency range. |
|
25. |
Contention
free period: In a wireless network contention free period is
the time when none of the stations are competing for transmission
in other words when there is no conflict between stations. Once
the contention free period is completed the Polled stations can
transmit. |
|
26. |
Convolution codes: Convolutional codes are a class of codes
which can detect and correct errors, where the code generated
depends not only upon the present bits but also on the preceding
bits in time. |
|
27. |
CRC:
Cyclic redundancy check abbreviated as CRC is a check sum on
integers (mod 2) and it’s a common error checking protocol. |
|
28. |
CSMA:
Carrier Sense Multiple Access - A listen before talk scheme used
to mediate the access to a transmission resource. All stations are
allowed to access the resource but are required to make sure the
resource is free before transmitting. |
|
29. |
CTS:
Clear to send (CTS) a signal from the receiving station to the
transmitting station granting permission to transmit data. In a
wireless network a station responds to a RTS with a CTS frame,
providing clearance for the requesting station to send data. |
|
30. |
DAC(D/A
converter)—DAC: Digital to Analog Converter, An electronic
device or a piece of software, often integrated , that converts a
digital number or signal into a corresponding analog voltage or
current |
|
31. |
DAMA:
Demand Assigned Multiple Access - a technique for sharing
satellite bandwidth among many users. |
|
32. |
Decibel
(dB): unit for expressing a logarithmic measure of the ratio
of two signal levels. It is most commonly used for expressing
power, voltage and current ratios as follows: Power Ratio dB = 10
log (P1/P2),
Voltage Ratio
dB = 20 log (V1/V2),
Current Ratio
dB = 20 log (I1/I2).
dBW =
decibels (power level) referenced to 1 watt.
dBm =
decibels (power level) referenced to 1 milli watt; often used
across 50 ohm input for receivers.
dBV =
decibels (voltage level) referenced to 1 volt across 50 ohms.
dBuV =
decibels (voltage level) referenced to 1 microvolt across 50 ohms.
dBuV/m =
decibels (voltage level) referenced to 1 microvolt per meter. |
|
33. |
DBPSK:
Differential Binary Phase Shift Keying is the modulation technique
in which the binary data is encoded as phase shift differences
between successive symbol periods. It is used for 1Mbps 802.11
transmission. |
|
34. |
Decoder:
A piece of hardware or software that decodes the encoded data into
the original format. |
|
35. |
Downlink:
The direction from the base station to the subscriber station. |
|
36. |
DQPSK:
Differential Quadrature Phase Shift Keying. A modulation method in
which bits are encoded as phase shift differences between
successive symbol periods. Four phase shifts are possible for an
encoding rate of two data bits per symbol. |
|
37. |
DSSS:
Direct Sequence Spread Spectrum. A transmission technique that
spreads a signal over a wide frequency band for transmission. |
|
38. |
Electro
magnetic Spectrum: Electro magnetic spectrum is a band of
electromagnetic waves arranged according to the wavelength and
frequency. |
|
39. |
Encoder:
A piece of hardware or software that encodes the data i.e. accepts
the message bits and adds redundancy according to a prescribed
rule there by producing encoded data at a higher bit rate. |
|
40. |
Encryption: Encryption is a process of converting the
information in a format such that it is not readable if
intercepted by a third party or unintended users. This is done
using key at transmitting station which intended receiving station
has in order to extract the information from received encrypted
data. |
|
41. |
Equalization: Equalization is the process to shape the
received pulses so as to compensate the effects of amplitude and
phase distortions caused by imperfections in the transmission
characteristics of the channel. It refers to any signal processing
or filtering technique used to reduce ISI. |
|
42. |
Fading:
The variation in received signal’s amplitude due to interference
is called as fading. |
|
43. |
FCC:
Federal Communications commission. The regulatory agency for
United States. |
|
44. |
Fidelity:
Faithfulness, accuracy. The ability of the electronic equipment to
reproduce the signal exactly at its input with full accuracy |
|
45. |
Fragmentation: It’s a process of breaking the large higher
level packets into smaller packets to fit through the wireless
channel. |
|
46. |
Frame:
The format of aggregated bits from a medium access control (MAC)
sublayer that are transmitted together in time. The Frame usually
consists of representation of the data to be transmitted
/received, together with other bits which may be used for error
detection or control. |
|
47. |
Frequency
hopping: Frequency-hopping spread spectrum (FHSS) is a method
of transmitting signals by rapidly switching a carrier among many
frequency channels, using a pseudorandom sequence known to both
transmitter and receiver. |
|
48. |
Frequency
Offset: Frequency offset is defined as the difference between
the ideal frequency and measured frequency. |
|
49. |
Guard
band: Unused frequency spaces between channels which prevents
overlapping of spectrum. |
|
50. |
Hertz:
A unit to measure the frequency. Cycles per second of a periodic
signal. |
|
51. |
IEEE:
The IEEE - Institute of Electrical and Electronics Engineers, Inc.
is a non-profit, technical professional association. |
|
52. |
IEEE
802.11a/b/g: are IEEE standards that define wireless LAN
technologies. 802.11b operates in the 2.4-GHz radio spectrum and
have a maximum data rate of 11 Mbps. 802.11a operates in the 5-GHz
spectrum and have a maximum data rate of 54.Mbps. 802.11g operates
in the same 2.4 GHz radio spectrum as 802.11b but at a rate of
54Mbps. |
|
53. |
IEEE
802.15.4: This IEEE standard defines the protocol and
interconnection of devices via radio communication in a Wireless
Personal Area Network (WPAN). 802.15.4 Operates in 868/915/2450
MHz band at a rate of 20/40/250 kbps. |
|
54. |
IEEE
802.16: IEEE 802.16
-2004
standard released in June 2004 specifies the air interface of
fixed broadband wireless access (BWA) systems supporting
multimedia services. |
|
55. |
Infrastructure network: A type of network where wireless
stations communicate via the access point. |
|
56. |
Inter
symbol Interference: When the signal bandwidth is close to the
channel bandwidth the pulses tend to overlap on each other this
overlapping of pulses is defined as Inter symbol Interference and
it is measured by eye patterns. |
|
57. |
Intermediate Frequency: Intermediate frequency is the
difference between the incoming frequency and oscillator
frequency. The output of oscillator is the intermediate frequency. |
|
58. |
IP:
Intellectual Property – a proprietary design which companies
license. |
|
59. |
ISM band:
Abbreviated for Industrial, Scientific and Medical band. ISM band
is a license free band which is set aside for Industrial,
scientific and Medical equipments. |
|
60. |
I/Q:
Abbreviated
for “in-phase/quadrature-phase.” Signals that are fundamental
products of individual In-phase and quadrature modulators, which
are exactly 90 degrees out of phase. |
|
61. |
Interoperability: The ability of heterogeneous systems and
networks to communicate and cooperate through specified standards. |
|
62. |
Jamming:
Jamming is defined as intentionally transmitting signals in a
particular frequency band to disrupt reception of signals. |
|
63. |
Line of
sight: In line of sight transmission the transmitting and
receiving stations (antennas) can see each other. It’s a clear
path between transmitting and receiving stations. |
|
64. |
MAC:
Medium Access Control layer is the lower layer in OSI model prior
to PHY layer. The primary functions of the MAC layer is to control
and access the physical medium, and also perform fragmentation and
de fragmentation of packets. |
|
65. |
Microwaves: The electromagnetic waves of very high frequency
used for heating and communication purpose. |
|
66. |
Modulation: Modulation is the process by which some
characteristics of the message signal are varied in accordance
with the modulating wave. |
|
67. |
Multipath:
In addition to direct path from transmitter to receiver there
exist several indirect paths. The interference caused due to these
indirect paths is called multipath. |
|
68. |
Multiplexing: Multiplexing is a technique where multiple
channels are combined for transmission over a single transmission
path. |
|
69. |
Node:
A connection point or a network junction, typically a computer or
a station. |
|
70. |
Noise:
Unwanted signal superimposed on a true signal. |
|
71. |
Non line
of sight: In non line of sight transmission technique the
stations/antennas (transmitting or receiving) need not see each
other; the path is not clear which results in signal degradation. |
|
72. |
OFDM:
Orthogonal Frequency Division Multiplexing (OFDM) is a modulation
technique in which a radio signal is divided into multiple narrow
frequency bands to transmit large amounts of data. 802.11a and
802.11g use OFDM. |
|
73. |
OFDMA:
Orthogonal Frequency Division Multiple Access. It’s a logical
extension of OFDM and a modulation/multiple access technique. |
|
74. |
OQPSK:
Offset (Orthogonal) Quadrature Phase Shift Keying is an
improvement over QPSK. In OQPSK technique the odd bits are delayed
by half bit interval w.r.t the even bits. |
|
75. |
OSI model:
Open Systems Interconnection Reference Model commonly known as OSI
Model describes seven layers Physical Layer, Data Link Layer,
Network layer, Transport layer, Session layer, Presentation layer
and Application layer. |
|
76. |
Packet:
A unit of data. Each message sent between two network devices is
often subdivided into packets by the underlying hardware and
software. Depending on the protocol the packets have their own
formats. |
|
77. |
PBCC:
packet binary convolution coding |
|
78. |
PCI:
Peripheral Component Interconnect
abbreviated as PCI- is a high-performance expansion bus for
PCs and work-stations. |
|
79. |
PCMCIA:
Personal Computer Memory Card International association. |
|
80. |
PER:
Packet error rate (PER) is an average fraction of transmitted
packets that are not detected correctly. |
|
81. |
Phase
Offset: Difference in reference phase of transmitted waveform
and received waveform is called phase offset, expressed in degree. |
|
82. |
PHY:
Common IEEE abbreviation for the PHYsical layer. |
|
83. |
Pilot:
A single frequency signal which is transmitted for synchronization
or reference purposes. |
|
84. |
PLCP:
Physical Layer Convergence Procedure which maps the frames to the
medium. |
|
85. |
PN
Sequence: A Pseudorandom Noise (PN) sequence is a
deterministic sequence known to both transmitter and receiver,
though it’s a deterministic signal it appears as a random sequence
with probabilistic properties. |
|
86. |
Point to
point: A dedicated path between two communication devices. |
|
87. |
PPDU:
PHY protocol data units (PPDU). Complete PLCP frame, including
PLCP headers, MAC headers, the MAC data field and the MAC and PLCP
trailers. |
|
88. |
Preamble:
A preliminary signal that is transmitted to control signal
detection and achieve synchronization between transmitters and
receivers in wired and wireless networks. |
|
89. |
Protocol:
A set of rules and regulations for communication. |
|
90. |
PSDU:
PLCP service data unit (PSDU) unit which represents the contents
of a PPDU. |
|
91. |
Pulse
Shaping: It is a process to alter the pulse shape in other
words tailoring the pulse shape in a controlled manner to overcome
ISI. |
|
92. |
PXI:
PXI (PCI eXtensions for Instrumentation) is a rugged PC-based
platform for measurement and automation systems. It is the open,
multivendor standard. |
|
93. |
QAM:
Quadrature Amplitude Modulation is a modulation technique which
uses different phases such as 16, 32, 64, and 256 and each state
is defined by a specific amplitude and phase. |
|
94. |
QOS:
Quality of Service (QoS) refers to the capability of a network to
provide better service |
|
95. |
QPSK:
Quadrature Phase Shift keying. A modulation method that encodes
bits as phase shifts. One of four phase shifts can be selected to
encode two bits. |
|
96. |
Randomization: Randomization is a process to systematically or
randomly reorder (shuffle) the data. Randomization starts with the
original data and calculates the appropriate test statistic on
each reordering. |
|
97. |
Receiver
Sensitivity: The ability of the receiver to pick up the
weakest signal. |
|
98. |
RF:
Abbreviated for Radio Frequency. |
|
99. |
Root Mean
Square (RMS): The square root of the average value of the
square of the instantaneous signal amplitude; a measure of signal
amplitude. |
|
100. |
Roaming:
Roaming is the term used to define the ability of a station to
move from one access point to another without being interrupted. |
|
101. |
RSSI:
Receiver Signal Strength Indication |
|
102. |
RTS:
Request to send (RTS) a signal from the transmission station to
the receiving station requesting permission to transmit data. In
wireless networks a station sends a RTS frame to another station
as the first phase of a two-way handshake necessary before sending
the data. |
|
103. |
Sampling
rate: Sampling rate defines the no of samples taken from a
continuous signal |
|
104. |
Shot
noise: Noise introduced in a communication system due to
random fluctuations in the electrons. |
|
105. |
SSID:
SSID is Service Set Identifier, it’s a unique name shared among
all clients and nodes in a wireless network. The SSID address is
identical for each clients and nodes in the wireless network. |
|
106. |
Synchronous: A form of communication transmission with a
direct timing relationship between input and output signals. The
transmitter and receiver are in sync and signals are sent at a
fixed rate. |
|
107. |
TCP/IP:
Transmission control protocol (TCP)/Internet protocol (IP). TCP
guarantees delivery of data and also guarantees the order in which
they were sent while IP takes care of the addressing. |
|
108. |
TDMA:
Time Division Multiple Access (TDMA) - A method of digital
wireless communications transmission allowing a large number of
users to access a single radio-frequency channel without
interference. Each user is given a unique time slot within each
channel. |
|
109. |
Thermal
noise: Noise introduced in a communication system due to
movement of electrons. |
|
110. |
Topology:
Geometrical arrangement of nodes in a network. There are various
kinds of topologies like star, mesh and ring. |
|
111. |
Turnaround
time: The time required to transmit a message and receive its
acknowledgement. |
|
112. |
Uplink:
it’s the transmission path from base station to a satellite |
|
113. |
Viterbi
decoder: Viterbi decoder is FEC (Forward error correction)
Device, which will decode the convolutional encoded data, and
correct random single bit errors. |
|
114. |
WEP:
Short for Wired Equivalent Privacy, a security protocol for
wireless local area networks (WLANs) defined in the 802.11b
standard. |
|
115. |
WiMAX:
WiMAX is an acronym for Worldwide interoperability for Microwave
Access a standards-based wireless technology which provides
broadband connections over long distances. |
|
116. |
WLAN:
Wireless Local Area Network. A Wireless LAN (WLAN) is a flexible
data communication system implemented as an extension to or as an
alternative for a wired LAN. With WLANs, users can access shared
information without looking for a place to plug in. Wireless LAN
systems provide WLAN
users access
to real-time information anywhere in their organization at work,
at home and on road. WLANs combine data connectivity with user
mobility through simplified configuration. |
|
117. |
WLL:
Wireless Local loop - is a system that connects subscribers to the
public switched telephone network (PSTN) using radio signals. |
|
118. |
WPAN:
Wireless Personal Area Network. Wireless personal area networks (WPANs)
are short range wireless networks that can be used to exchange
information between devices in the reach of a person and his
personal space within 10-20 meters. |
|
119. |
ZigBee:
The best example representing WPANs is the recent industry
standard: ZigBee.
The ZigBee
Alliance is
an association of companies working together to enable reliable,
cost-effective, low-power, wirelessly networked, monitoring and
control products based on an open global standard. The goal of the
ZigBee Alliance is to provide the consumer with ultimate
flexibility, mobility, and ease of use by building wireless
intelligence and capabilities into every day devices. ZigBee and
the underlying IEEE 802.15.4
promise to
give the market a cost-effective standards-based wireless network
that supports low data rates, low power consumption, security, and
reliability. |
