Cabletron Systems RoamAbout Access Point Manual page 31

To avoid radio interference, adjacent Access Points should be set to different channels that
are at least five channels apart. The Access Points do not necessarily have to be in the same
wireless network. For example, you have three Access Points whose coverage areas
overlap; set the channels to 1, 6 and 11, if possible. Due to local radio regulations, not all
channels are available in all countries.
In a LAN-to-LAN configuration, the Access Points must be set to the same channel.
In an ad-hoc network, all clients must use the same channel to communicate. Since the
RoamAbout PC Cards use the same default channel, this is only an issue when clients use
other PC Cards set to a different channel.
See the "Supported Frequency Sub-Bands" section on page A-5 for a list of channels
supported by country.
Transmit Rate
The transmit rate identifies the preferred data transmission speed of the Access Point. The
actual data transmission speed is subject to the type of PC Cards at both ends of the wireless
link and the communications quality of the link.
Transmissions at faster rates allow for higher data throughput and quicker network
response times. However, transmissions at lower rates are usually more reliable and cover
longer distances than the higher rates. You might use a lower rate in the following
situations:
•
The client is at the extreme edge of the coverage area (see Figure 2-1). Using a lower
rate covers the longer distance more reliably than a higher rate.
•
There are numerous retransmissions due to a low signal level. Using a lower transmit
rate prevents the PC Card from slowing network response times by transmitting data
unsuccessfully at a higher rate then retransmitting at a lower rate.
As shown in Figure 2-1, an Access Point can have clients using different transmit rates in
a wireless infrastructure network.
The following sections describe the auto rate and fixed rate settings.
Auto Rate
With the Auto Rate option, the PC Card in a client or Access Point automatically switches
to a lower rate when data transmissions fail more than once. Shortly after completing the
transmission, the PC Card returns to transmitting data at the higher rate.
Understanding Wireless Network Characteristics 2-3
Transmit Rate