Transmit Power And Cable Loss - Airspan ASWipLL Quick Installation And Configuration Manual

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Q u i c k I n s t a l l a t i o n & C o n f i g u r a t i o n G u i d e

Transmit Power and Cable Loss

Airspan's ASWipLL radios provide transmit power compensation for power attenuation caused by cable loss
(of cable connecting to external antenna). Cable loss is the loss of radio transmit (Tx) power as heat, and
directly proportional to cable length and quality, and operating frequency. In accordance with FCC regulations,
when operating in unlicensed bands, the external antennas must provide an EIRP of ≤ 36 dBm to prevent
interference with other radios. EIRP is defined as max. Power Output plus (+) Antenna Gain minus (-)
Cable Loss. Therefore, to adhere to this EIRP limitation, when purchasing antenna cables, take into
consideration cable loss per cable length. The table below lists examples of cable loss per cable length.
The following procedure describes how to configure (using WipManage) BSR transmit power for 23 dBm when
using a 40-foot cable with a 4-dB cable loss.
To define BSR transmit power taking into consideration cable loss (using WipManage):
1. In the BSR Zoom window, from the Configuration menu, point to RF, and then choose Power Settings.
2. Ensure the Power Management Mode Active check box is cleared. On the Power Level slide ruler,
define the BSR's maximum power level, e.g. 23 dBm.
3. In the Loss Compensation field, enter the power to compensate for power attenuation due to cable length
(i.e. cable loss compensation), e.g. 4 dB.
4. Click Apply, and then reset the BSR to apply the new power settings.
Therefore, taking cable loss into consideration, the total power level of 27 dBm (23 plus 4) is achieved.
Notes:
1) Airspan does not supply external antenna cables. It is the responsibility of the installer to provide the
cable and ensure the cable characteristics (e.g. length and cable loss) enables adherence to FCC's
regulations concerning maximum EIRP (i.e. of less than or equal to 36 dBm).
2) ASWipLL 900 MHz is capable of transmitting at up to 30 dBm. However, in accordance with FCC
regulations, transmit power is limited to 23 dBm in the 4 Mbps mode, and 18 dBm in the 3 Mbps mode.
10 Airspan Networks Inc.
AS W i p L L 9 0 0 M H z
Power compensation
due to cable loss
13070311-02