Operation Manual

Fiber Distributed Antenna System (Fiber DAS)
19
DOI380X FOI
The DOI380X offers a Coarse wavelength division multiplexing (CWDM) solution that allows up to 16 optical
wavelengths to share one single-mode fiber. CWDM helps end users overcome limited fiber infrastructure issues
when multiple sectors are required, when MIMO solutions are required, or when the fiber needs to be shared with
other services such as IP cameras or private IP systems.
The "X" in the DOI308X is replaced with the wavelength code from the chart below
. For example, the default
DOI380X card would be DOI380O meaning the card has the 1550nm optical filter to be used on the transmit path.
Wavelengths K through R are typically used for downlink signals. Wavelengths A though H are typically used for
uplink signals to limit uplink noise. Remote units will require CWDM filters in the FOR to correspond to the FOI
wavelengths.
Table 13
Code (nm) Note Code (nm) Note
A 1270 UL 1 J 1450
Guard
††
B 1290 UL 2 K 1470
C 1310 UL 3 (std) L 1490
D 1330 UL 4 M 1510
E 1350 UL Spare N 1530
F 1370
WAS
†
† WAS - Use caution when using these wavelengths on older fiber due to water absorption losses
O 1550 DL
G 1390
WAS
†
P 1570
H 1410 Q 1590
I 1430
Guard
††
†† Wavelengths typically not used to allow for greater separation between UL and DL
R 1610
Wavelength Chart
The optical link budget for CWDM is calculated differently from typical WDM systems, where only fiber and splitter
losses are of concern. For CWDM, the number of optical filters is taken into consideration. Since optical filters are at
both the head end and remote, loss is doubled.
Channel losses are dependent on the actual wavelengths used. The chart below provides an approximate loss
considering both the head end and remote filters. Actual fiber and connector losses are in add to the CWDM filter
loss.
Table 14 Channel Loss
Channels loss dBo
2 2.4
4 3.2
8 5.4
16 7.4