Integrated Wireless-pon access Network Architectures Milos Milosavljevic

Chapter 2 Next Generation Access Networks 
26 
As a result, several multi-wavelength recommendations have been proposed, concentrating 
primarily on the architecture level with some initiatives developed recently in the protocol side 
with the generation of dynamic wavelength allocation algorithms for EPON [47] and GPON 
[38] relative designs. For reasons of convergence with legacy GPONs and EPONs, new 
operating wavelengths would have to coexist with those of the legacy networks [2].
An example of an architecture demonstrating multi-wavelength transmission over a splitter-
based EPON has been proposed in [48]. Shown also in Figure 2-4, tuneable optical filters are 
utilised at ONUs to select the desired wavelength, following their broadcasting from the passive 
splitter. The filters for downstream and feeding light at an ONU are independently tuneable 
allowing the combination of any downstream wavelength with any upstream wavelength for an 
ONU. The colourless transmission is achieved by means of the reflective semiconductor 
amplifiers (RSOAs). However, this approach would require typically dual feeder fibres in order 
to limit the Rayleigh backscattering effect at the RSOA. Subsequently, a single-port power 
splitter in the remote node will need to be replaced with dual-port for data transmission and 
seeding light. In addition, multiple AWGs in the OLT would be needed for downstream and 
upstream transmission and to provide the seeding light for the RSOA.
Figure 2-4: Multi-wavelength EPON [48] 

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Chapter 2
Alternatively, in support of the GPON standard, enhancements to address the network of the 
future requirements have been
wavelength band operation. To that extent, multi
deployed splitter-based PONs should be demonstrated at the slightest modification 
hardware, supporting e.g. 
GPON. To ensure that next generation and traditional ONUs can operate concurrently in the 
same PON the standard defines the application of
by traditional ONUs. As displayed
(NGA) and RF (e.g. video or wireless) related services 
and broadcasted to each ONU via passive splitter. Inside the ONU a specific wavelength is 
selected by wavelength division 
Rx. The wideband blocking filter (WBF) could then be used to separate different services 
supported by specific ONU
* V-Tx-Video Transmitter, N-splitter size, IF