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2. System Description
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© 2007 Moseley, Inc. All Rights Reserved.
602-14886-01, Rev. A
Crosspoint
Switch
Framer
Modem East
Modem West
IO
Up to 32 E1
Up to 32 E1
Up to 16E1
Up to 16E1
Optional IO
Crosspoint
Switch
Framer
Modem East
Modem West
IO
Up to 32 E1
Up to 32 E1
Up to 16E1
Up to 16E1
Optional IO
Repeater Example
Add/Drop Example
Figure 2-13. (a) Crosspoint Switch used a passthrough in repeater
configuration. (b) Crosspoint Switch allows access for add/drop.
2.13Power Management
RF power management is a radio design feature that controls the power level (typically
expressed in dBm) of the RF signal received from a transmitter by a receiver. The
traditional goal of power management is to ensure that the RF signal at a receiver is
strong enough to maintain the radio link under changing weather and link conditions.
traditional goal of power management is to ensure that the RF signal at a receiver is
strong enough to maintain the radio link under changing weather and link conditions.
The Quadrature Amplitude Modulation (QAM) is not a constant envelope waveform.
Therefore, the average power and peak power are different. The difference in peak and
Therefore, the average power and peak power are different. The difference in peak and
average power depends on the constellation type and shaping factor, where spectral
efficiency such as more constellation points or lower shaping factor leading to peak
efficiency such as more constellation points or lower shaping factor leading to peak
powers higher than average powers. The peak power is typically 5-7 dB greater than the
average power and never exceeds 7 dB. Regulatory requirements are sometimes based
average power and never exceeds 7 dB. Regulatory requirements are sometimes based
on peak EIRP which is based on peak power and antenna gain.
Traditional power management techniques such as Constant Transmit Power Control
(CTPC) and Automatic Transmit Power Control (ATPC) transmit at a high power level to
(CTPC) and Automatic Transmit Power Control (ATPC) transmit at a high power level to
overcome the effects of fading and interference. However, these techniques continue to
operate at a higher power level than needed to maintain the link in clear weather.
operate at a higher power level than needed to maintain the link in clear weather.
Because transmit power remains high when the weather clears, the level of system
interference increases.
interference increases.
Radios operating at high transmit power will interfere with other radios, even if the
interfering source is miles away from the victim. High interference levels can degrade
interfering source is miles away from the victim. High interference levels can degrade
signal quality to the point that wireless radio links become unreliable and network
availability suffers. The traditional solution to system interference is to increase the
distance between radios. However, the resulting sparse deployment model is
availability suffers. The traditional solution to system interference is to increase the
distance between radios. However, the resulting sparse deployment model is
inappropriate for metropolitan areas.