Resource allocation

The different candidate paths will be evaluated to provision a traffic demand of 152 Gbps between nodes F1 and F10 according to the network architecture under consideration:

F1 F2 F3 F4 F12 F5 F6 F10 F11 F8 F7 F9 F18 F25 F16 F13 F14 F15 F17 F19 F20 F21 F22 F26 F27 F28 F23 F29 F24 F30 SOURCE DEST.

A.2.1. WDM single line rate

According to Algorithm 2, it is checked whether there is transparent transmission feasibility on the existing candidate paths (transmission reach of the TSP must be greater than or equal to the path length). The transmission reach values are 2200 and 1880 km for 40 Gbps and 100 Gbps, respectively. Therefore, the physical constraints would be fulfilled for any of the calculated candidate paths. After that, it is checked whether in each of the links of the paths there are common available wavelengths (i.e. 4 and 2 wavelengths for SLR 40 Gbps and SLR 100 Gbps, respectively) to fulfill the wavelength continuity constraint. For instance, in the first candidate path, the WA would be possible since there are 5 available common wavelengths that could be used to provision the service (i.e. wavelengths 3, 5, 15, 16 and 20) as shown in Figure A.2. Hence, for this and the other feasible candidate paths, an EEPGMetric is calculated as in Eq. (2).

Figure A.2. Example of wavelength occupancy in the first candidate path.

Being PCTRANS and SOPath constant for all the candidate paths (i.e. the same type of TSP has to

be employed), the only variable factor for the calculation of EEPGMetric is PCLINKS in Eq. (10). In

other words, the most convenient allocation mainly depends on the PC of the number of traversed nodes and OAs along the path. Assuming that the network has available spectral resources in all the paths, the following EEPG metrics are obtained for the first five paths as shown in Table A.2.

As can be noticed, the first candidate path offers the maximum EEPGMetric as it traverses four nodes (F1, F4, F6 and F10) and 4 in-line OAs (one in F1-F4 link, two in F4-F6 link, and one in F6- F10), while the other possibilities include a larger number of OAs and/or OXCs. Accordingly, the service provisioning will be realized in the first candidate path (k=1) in both SLR approaches.

Table A.2. EEPGMetric obtained for the candidate paths in SLR 40 Gbps and SLR 100 Gbps. k

SLR 40G SLR 100G

PCPath [W] EEPG Metric [bits/Joule/GHz]

PCPath [W] EEPG Metric [bits/Joule/GHz] 1 624.68 1216623 918.34 1655160 2 629.6875 1206948 920.84 1650667 3 628.0625 1210071 920.03 1652120 4 632.56 1201467 922.28 1648090 5 636.125 1194734 924.06 1644915

A.2.2. WDM mixed line rate

The RWA in WDM MLR follows the steps described in Algorithm 3. As mentioned earlier, in a WDM MLR architecture, a particular traffic demand can be provisioned by different combinations of TSPs (i.e. LRComb). Therefore, the potential LRComb are calculated to serve the traffic demand of 152 Gbps and sorted in descending order of EEPG at the TSPs, as shown in the LRCombList presented in Table A.3.In this example, the three line rates (10, 40 and 100 Gbps) can be used as they provide enough transmission reach in the candidate paths of Table A.1.

APPENDIX B - ROUTING AND RESOURCE ALLOCATION 169

Table A.3. LRCombList sorted in descending order of EEPG at the TSPs.

LRCombIndex Number of TSPs PC of the TSPs [W] EEPGMetric at the TSPs[bits/Joule/GHz] 10Gs 40Gs 100Gs 1 0 0 2 702 2165242 2 0 4 0 392 1938776 3 0 2 1 547 1852529 4 2 1 1 517 1470019 5 4 3 0 430 1009967 6 6 0 1 555 782496.8 7 8 2 0 468 649572.6 8 12 1 0 506 462146.5 9 16 0 0 544 349264.7

As shown, the preferred LRComb for the allocation would be the one composed of 2 TSPs of 100 Gbps (LRCombIndex equal to 1). The WA evaluation is then started for the first LRComb in all the candidate paths presented in Table A.1. The WA for MLR is significantly different from that carried out for SLR due to the presence of two wavebands separated by a GB of 4 wavelengths (i.e. the first waveband is used for 10 Gbps transmissions, whereas the second one is dedicated to 40/100 Gbps). As can be noticed, the two first LRComb correspond to the cases of SLR 100 Gbps and SLR 40 Gbps, which were presented in the previous section. If there are enough and common wavelengths on the second part of the spectrum in any of the candidate paths, these options will be preferred for WA as they provide higher EEPG (especially the LRCombs with SLR 100 Gbps as shown in Table A.2).

One particularity of MLR is given by the presence of a GB that can be moved whether more wavelengths are required on the first or second part of the spectrum. For instance, in the example presented in Figure A.3, there is only one available wavelength on the second band, but the GB of the first link (F1-F4) can be moved one wavelength position to the left to increase the number of 40/100 Gbps. This will enable the utilization of the first LRComb in the list (LRCombIndex equal to 1, which employs 2 TSPs of 100 Gbps).

Figure A.3. Example of wavelength occupancy in the first candidate path, before and after moving the GB.

A.2.3. Elastic optical network

The RMLSA in EON follows the steps described in Algorithm 4. For each of the candidate paths in Table A.1, it is checked which MF meet the physical constraints in terms of transmission reach. For those paths whose length is between 500 and 1000 km, three MFs can be used (i.e. BPSK, QPSK and 8QAM), whereas for those with distances over 1000 km, only BPSK and QPSK would be feasible. The number of required subcarriers including GB varies according to the MF i.e. 15, 9 and 7 subcarriers with BPSK, QPSK and 8QAM formats, respectively.

For those candidate paths where common spectral resources are available along all the links, an EEPGMetric is calculated for the different MFs as in Eq. (2). The EEPGMetric calculated for the

first five candidate paths is shown in Table A.4. As can be seen, 8-QAM is definitely the most energy- and spectral-efficient MF choice (based on the EEPGMetric) in any of the evaluated candidate paths. Moreover, 8-QAM is also the MF that requires the reservation of a smaller number of subcarriers, which also increases the chances of finding a suitable spectrum range available in the links of the candidate path.

Regarding the spectrum allocation, similarly to the WA in WDM architectures, the wavelength (or spectrum) continuity constraint must be fulfilled. Furthermore, it is also necessary to consider the contiguity constraint (subcarriers in the super-channel must be contiguous).

Table A.4. EEPGMetric obtained for the candidate paths in EON with the feasible MF. k

BPSK QPSK 8-QAM

PCPath [W] EEPG Metric [Mb/Joule/GHz] PCPath [W] EEPGMetric [Mb/Joule/GHz] PCPath [W] EEPGMetric [Mb/Joule/GHz] 1 1691.5 299.5369 1152.3 732.83385 986.586 1100.47607 2 1696.2 298.70691 1155.1 731.05744 998.77 1087.05136 3 1694.7 298.9713 1154.2 731.62749 988.06 1098.83437 4 1698.9 298.23219 1156.7 730.0462 990.03 1096.64786 5 1702.2 297.65402 1158.7 728.78609 991.59 1094.92258