Modifying Radio Settings - HP ProCurve 420 Management And Configuration Manual

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Modifying Radio Settings

The access point can operate in three standard modes, IEEE 802.11b only,

802.11g only, or a mixed 802.11b/802.11g mode.

Both the IEEE 802.11g and 802.11b standards operate within the 2.4 GHz band.

In a wireless LAN environment there can often be interference from other

2.4 GHz devices, such as cordless phones. If you experience poor wireless

LAN performance, try to limit any possible sources of radio interference

within the service area.

The IEEE 802.11g standard is an extension of the IEEE 802.11b standard and

enables client stations with 802.11b wireless network cards to associate to an

802.11g access point. However, the 802.11b standard uses Complementary

Code Keying (CCK) modulation technology to achieve a communication rate

of up to 11 Mbps, whereas 802.11g uses Orthogonal Frequency Division

Multiplexing (OFDM) to reach rates of up to 54 Mbps. (Note that the 802.11g

standard is backward-compatible with 802.11b and therefore includes the

ability to use OFDM or CCK modulation.) To support both 802.11g and 802.11b

clients, the access point has to first communicate with all clients using CCK

and only switch to OFDM for data transfers between 802.11g-compatible

clients. This mechanism has the effect of reducing the maximum throughput

for 802.11g clients in the network.

Working in its mixed "b/g" mode, the access point will experience reduced

data throughput, even if there are no 802.11b clients active in the network. To

achieve a higher throughput, you can set the access point to operate in 802.11g-

only mode, which ignores all 802.11b clients in the service area.

Both the IEEE 802.11g and 802.11b standards operate within the 2.4 GHz band.

If you are operating in "802.11g-only" mode, any 802.11b devices in the service

area will contribute to the radio frequency noise and affect network perfor

mance.

External Antenna Configuration. If you install an external antenna for

the access point, the antenna mode must be set for the antenna type; either

diversity or single. Also, the access point's transmit power must be limited to

conform to local regulations. Use the regional settings for each external

antenna option in each radio mode as provided in the Transmit Power Control

tables (see page 5-62).

Access Point Configuration

5-53

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