Research On Multicast IA-RWA Algorithms And MC-OXC Architectures In Transparent Optical Network

By eliminating the redundant O/E/O interfaces at transit nodes, transparent optical network is able to transmit the client data from the source to the destination all-optically without being aware of its modulation format, bit rate as well as network protocol, and thus is expected to gradually replace the existing opaque optical network. With the emergence of various multicast applications such as video conference, high-definition TV and distributed game, there is an intensely increasing demand to enable optical multicasting services in the transparent optical network in order to satisfy their bandwidth requirements with improved network efficiency and flexibility.Optical signals in transparent optical network are subjected to physical impairment constraints. Various impairments such as amplified spontaneous emission noise, polarization mode dispersion and non-linear effects may be accumulated along the route and eventually result in significant signal degradation if dealt improperly. Therefore, a lot of impairment-aware routing and wavelength assignment (RWA) algorithms have been proposed for the point to point service. This paper is committed to investigating a novel impairment-aware multicast algorithm based on K shortest paths. In this algorithm, a novel path weight factor is introduced to jointly consider the processes of routing and wavelength assigning, and multiple paths with the biggest factor are considered to be candidates. Simulation results show that the proposed algorithm achieves lower connection blocking rate, higher resource utilization and more balanced traffic distribution.Multicasting in transparent optical network also relies on the nodes with multicast-capable optical cross connection (MC-OXC) function. Existing MC-OXCs perform differently in aspects of multicast/unicast traffic classification, physical impairment loss, component size and blocking feature for switching. This paper makes a comparison among these MC-OXCs and proposes an improved TaSM architecture. The TaSM combines the advantages of MOSaD and TCM, and can support a splitting for arbitrary number of ports and thus is expected to be well applied in mesh network. The TaSM features with a similar component size as MOSaD and TCM but a better traffic classification. At the transit nodes, there is a type of multicast traffic with destinations group involving the local node and another node in the network. After a small part of signal power is tapped for the local station, the remaining signal traffic has only one destination as a unicast signal. For such a case, the TaSM architecture re-switches the unicast signal with the WRS module, avoiding unnecessary power loss due to splitting. Statistics show that it is more flexible in traffic classification and able to achieve a power loss saving of around 70% over MOSaD when processing some specific traffic.In conclusion, in order to relieve the physical impairment constraints and enhance the network flexibility in transparent optical network, this paper conducts some exploratory studies on impairment-aware multicast algorithms and MC-OXC architectures, and some improvements compared with current researches are verified.