6 Site Planning
50
6.1.3
Path Loss Considerations
The path loss is the amount of attenuation the radio signal undergoes between the two ends
of the link. The path loss is the sum of the attenuation of the path if there were no obstacles in
the way (Free Space Path Loss), the attenuation caused by obstacles (Excess Path Loss)
and a margin to allow for possible fading of the radio signal (Fade Margin).
capability
seasonal
fade
excess
space
free
L
L
L
L
L
<
+
+
+
_
Where
space
free
L
_
Free Space Path Loss (dB)
excess
L
Excess Path Loss (dB)
fade
L
Fade Margin Required (dB)
seasonal
L
Seasonal Fading (dB)
capability
L
Equipment Capability (dB)
Equation 1 - Path Loss
6.1.4
Definitions
The equipment capability is given in Table 9, Table 11 (IP Mode) and Table 10, Table 12
(TDM Mode). Each table gives Link Loss, Output Power and System Thresholds for PTP 500
Series Bridge in all modulation modes.
Adaptive Modulation will ensure that the highest throughput that can be achieved
instantaneously will be obtained taking account of propagation and interference. The
calculation of Equation 1 needs to be performed to judge whether a particular link can be
installed. When the link has been installed, web pages provide information about the link loss
currently measured by the equipment, both instantaneously and averaged. The averaged
value will require maximum seasonal fading to be added, and then the radio reliability of the
link can be computed.
For minimum error rates on TDM links the maximum modulation mode should be limited to
64QAM and channel coding rate of R= 0.75, denoted as 64QAM 0.75.
Содержание PTP 54500
Страница 1: ...PTP 500 Series User Guide MOTOROLA POINT TO POINT WIRELESS SOLUTIONS ...
Страница 2: ......
Страница 132: ...8 Web Page Reference 130 Figure 65 Spectrum Management Slave Screen With Operational Restrictions ...
Страница 190: ...14 Data Rate Calculations 188 Figure 111 QPSK 0 50 Single Payload Figure 112 QPSK 0 75 Single Payload ...
Страница 191: ...14 Data Rate Calculations 189 Figure 113 16 QAM 0 50 Single Payload Figure 114 16 QAM 0 75 Single Payload ...
Страница 192: ...14 Data Rate Calculations 190 Figure 115 64 QAM 0 67 Single Payload Figure 116 64 QAM 0 83 Single Payload ...
Страница 193: ...14 Data Rate Calculations 191 Figure 117 QPSK 0 50 Dual Payload Figure 118 QPSK 0 75 Dual Payload ...
Страница 194: ...14 Data Rate Calculations 192 Figure 119 16 QAM 0 50 Dual Payload Figure 120 16 QAM 0 75 Dual Payload ...
Страница 195: ...14 Data Rate Calculations 193 Figure 121 64 QAM 0 67 Dual Payload Figure 122 64 QAM 0 83 Dual Payload ...
Страница 205: ...16 Legal and Regulatory Notices 203 16 4 Exposure See Section 2 Avoiding Hazards ...