1. The triplexer and analog RF receiver increase the cost of ONU.
2. The overlaid analog service creates additional management complexities.
MSOs may be able to take the advantage of their existing legacy analog
HFC system and the know-how they have developed for that. However, for
conventional telecom operators entering the triple-play market, it is much
better to leapfrog with digital IPTV technology as they do not have the legacy
burden of analog TV distribution systems.
3. Regulatory bodies around the world are now phasing out analog TV broad-
cast and replacing them with digital services.
2.5.4 Security Concerns in Power-Splitting PON
One important concern of power-splitting PON is the broadcast nature
of the downstream channel, which makes it easy to eavesdrop down-
stream communication signals by malicious users. It should be realized
that because of the directional nature of the optical star coupler at the
remote node, an ONU cannot listen to the upstream transmission from
another ONU.
T
R
R
T
OLT
ONU
1.3 µm
1.49 µm1.49 µm
1.3 µm
Data
Data
EDFA
T
R
OLT
1.49 µm
1.3 µm
Data
Satellite
Headend
1.55 µm
STB
TV
1.55 µm
RN
Splitter
. . .
1.55 µm
1.55 µm
Figure 2.13 Overlaying analog broadcast TV services on a TDM-PON using the 1:55-mm
wavelength.
36 PON Architectures Review

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