Alvarion BreezeACCESS Wi2, Системное руководство

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98 BreezeMAX Wi² and BreezeACCESS Wi² System Manual
Chapter 6 - Wireless Configuration
6.1.3 Configuring Overlapping Wireless Cells
Overlapping wireless cells occur when two or more APs are within transmission range of each other.
This may be under your control, (for example, when you use several cells to cover a large location),
or out of your control (for example, when your neighbors set up their own wireless networks). In
either case, the problems you face are similar.
6.1.3.1 Performance Degradation and Channel Separation
When two wireless cells operating on the same frequency overlap, throughput can be reduced in
both cells. Reduced throughput occurs because a wireless user that is attempting to transmit data
defers (delays) transmission if another station is transmitting. In a network with many users and
much traffic, these delayed transmissions can severely affect performance, because wireless users
may defer several times before the channel becomes available. If a wireless user is forced to delay
transmission too many times, data can be lost.
Delays and lost transmissions can severely reduce throughput on a network. To view this
information about your network, select Status > Wireless. For recommendations on using this
information to diagnose wireless problems, see the online help for this page .
The following example shows two overlapping wireless cells operating on the same frequency.
Since both APs are within range of each other, the number of deferred transmissions can be large.
The solution to this problem is to set the two networks to different channels with as great a
separation as possible in their operating frequencies. This reduces crosstalk and enables client
stations connected to each AP to transmit at the same time.
Figure 6-1: Overlapping Wireless Cells Operating on the Same Frequency