User guide

45 Mbps Backhaul User Guide

Issue 3, December 2004 Page 47 of 113

Max Transmit Power This attribute controls the maximum transmit power the unit is permitted to use when

installing and executing the wireless link.

Ranging Mode During installation the wireless units perform automatic ranging. The ranging mode allows the

installer to control the behavior of the systems automatic ranging algorithms. The default value is 0 to 40 km

. If

the installer is required to install a link of greater than 40 km then the ranging mode attribute MUST be

configured to 0 to 130 km mode. Likewise selecting the 0 to 5 km mode for links under 5 km will give you

optimal performance. Installers that know the range between the two wireless units to within ± 1 km can use the

target range mode. The main advantage of the target range mode is that it reduces the time taken by the units to

range. To use the target range mode the installer MUST select the Target as the ranging mode and enter the

approximate range in km in the Target range data entry field.

Once the installer is satisfied with the wireless configuration options then the ‘Submit Wireless Configuration’

button or the ‘Next’ link should be clicked.

Spectrum Management Control Is used to configure the 45 Mbps Backhaul Spectrum Management features,

see section 6.3.5 for more details. i_DFS is the abbreviation for intelligent Dynamic Frequency Selection, this

feature continually monitors the 5.8 GHz spectrum looking for a the channel with the lowest level of on channel

and co-channel interference. Fixed frequency mode allows the installer to fix the transmit and receive

frequencies on the units. The frequencies may be configured symmetrically or asymmetrically.

6.3.3.3.1 Lower Center Frequency

The 45 Mbps Backhaul software allows a user to optionally adjust the channel center frequencies. The default

starting channel center frequency is 5734 MHz. This value can be adjusted to either 5732 or 5736 MHz.

Changing the Lower Center Frequency attribute causes all channel center frequency to be offset. It effectively

slides the channelization up or down 2 MHz.

Warning: The lower center frequency attribute must be configured to the same value for of both the master and

slave. Failure to do so will cause the wireless link to fail reestablishment. The only way to recover from this

situation is to modify the Lower Center Frequency attribute so that they are identical on both the master and

slave unit.

6.3.3.3.2 Fixed Transmit Frequency, Fixed Receive Frequency

The 45 Mbps Backhaul software allows a user to optionally fix transmit and receive frequencies for a wireless

link. Once configured the spectrum management software will not attempt to move the wireless link to a

channel with lower co and adjacent channel interference. Therefore this mode of operation is only

recommended for deployments where the installer has a good understanding the prevailing 5.8 GHz interference

environment. Figure 19 shows an example fixed frequency configuration. The lower center frequency is set to

its default values and the Fixed Transmit Frequency is set to 5740 MHz and the Fixed Receive Frequency is set

to 5782 MHz. Care must be taken when configuring the Fixed Transmit and Receive Frequencies to ensure that

both frequencies are on the same 6 MHz channel raster as the Lower Center Frequency. For example both the

Fixed Transmit and Receive Frequencies must be a multiple of 6 MHz from the Lower Center Frequency (5740

= 5734 + 6 MHz) and (5782 = 5734 + 6 MHz × 8).

If preferred 45 Mbps Backhaul range functions can be configured to operate in miles, see the

Properties page in section 6.3.12.