Introduction
IEEE 802.11 (a/b/g)
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Operating Manual 1171.5283.12 ─ 18
2
Introduction
The R&S
Signal Generator provides you with the ability to generate signals in accord-
ance with the Wireless LAN standards IEEE 802.11a, IEEE 802.11b and IEEE 802.11g.
(IEEE 802.11) standard WLAN.
IEEE 802.11 stands for a wireless LAN standard prepared by ANSI/IEEE Institute of
Electrical and Electronics Engineers). A brief description of the standard is given in the
following. For a detailed description see the corresponding ANSI/IEEE specifications.
In 1990, IEEE founded the work group 802.11 which issued a first version of the 802.11
standard in June 1997. This standard defines two transmission methods: an infrared
interface and radio transmission in the ISM band around 2.4 GHz.
Radio transmission can alternatively be carried out via frequency hopping spread spec-
trum (FHSS) or direct sequence spread spectrum (DSSS).
Originally, two data transmission modes were defined for the DSSS method.
●
1 Mbps data rate with DBPSK modulation
●
2 Mbps data rate with DQPSK modulation
Both modes spread the information data sequence with an 11-chip Barker sequence,
and operate with a chip rate of 11
Mcps.
In spring 1999, the standard was extended by an OFDM mode, 802.11a, in the 5 GHz
band. Soon afterwards, in summer 1999, the DSSS mode was extended, too. This
expansion to include the new data rates of 5.5
Mbps and 11
Mbps is defined in the
802.11b standard. A new modulation mode, complementary code keying (CCK), was
introduced (see following sections).
Standard 802.11g issued in 2003 extends standard 802.11b with higher transmission
rates. It includes the previous 802.11b standard and implements the OFDM transmis-
sion of standard 802.11a in the 2.4 GHz ISM band. In the physical layer, the packet
structure and modulation format of the OFDM modes are identical in 802.11g and
802.11a, only different transmission frequencies are used.
The 802.11 wireless LAN standard is a packet-oriented method for data transfer. The
data packets are transmitted and received on the same frequency in time division
duplex (TDD), but without a fixed timeslot raster. An 802.11 component can only trans-
mit or only receive packets at any particular time.
The R&S
Signal Generator simulates IEEE 802.11a-g WLAN at the physical on the
physical layer. Two simulation modes are offered:
In the framed mode a sequence of data packets with the frame structure defined by the
standard is generated. A MAC header and a frame check sequence can be activated.
In the unframed time mode a non-packet-oriented signal without frame structure is
generated, with the modulation modes and data rates defined by the IEEE 802.11.
The following list gives an overview of the options provided by the R&S
Signal Genera-
tor for generating a IEEE 802.11a-g WLAN signal:
●
Physical Layer modes OFDM (IEEE.802.11a/g), and CCK/PBCC (IEEE.802.11b/g).
