Crosstalk-Aware Spectrum Defragmentation based on Spectrum Compactness in SDM-EON Yongli Zhao State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications (BUPT), Beijing 100876, China Tel : +86-10-61198108; Email: yonglizhao@bupt.edu.cn; Web: ipoc.bupt.edu.cn Group Meeting, 27th May 2016
Outline 1. Background of SDM-EON 2. Problem description 3. Spectrum compactness in SDM-EON. Crosstalk-aware RSCA in SDM-EON 5. Spectrum defragmentation in SDM-EON 2
Multi-dimensional resource in optical networks PMM (a) Polarization Frequency Multi-dimensional Resources in Optics (b) WDM/EON SDM-EON SDM Space Time OTDM (c) (d) Yongli Zhao, Jie Zhang, et al., Mode and Wavelength Allocation in Multi-Dimensional Optical Networks, ACP201, Shanghai, China, Nov.201 3
Fiber Switching Box Mode Switching Box Mode Switching Box Fiber Switching Box Switch fabric of SDM-EON with multi-mode fiber M M M L L Wavelength Switching Box L L M drop add M Mode De-multiplexer M Mode Multiplexer L Wavelength De-multiplexer L Wavelength Multiplexer Yongli Zhao, Jie Zhang, et al., Mode and Wavelength Allocation in Multi-Dimensional Optical Networks, ACP201, Shanghai, China, Nov.201
... WSS... Switch fabric of SDM-EON with multi-core fiber 5 5 Multicore Fiber 1 2 3 0 6 SDM DeMUX EDFA WSS EDFA SDM MUX 1 2 3 0 6 Multicore Fiber Add Drop TR 1 TR 2. Transceiver pool TR M The transceiver resources consist of a transceiver pool, supplying the appropriate sub-transceivers according to the traffic requirement. 5
Core and spectrum switching with spectrum continuity Core 1 Slice 1 Slice 2 Core 1 Core 2 Slice 2 Slice 3 Core 2 Core 3 Slice 3 Slice 1 Core 3 Link 1 Link 2 Core and spectrum switching In the switch fabric, different spectrum slots can be switched between different cores, but must follow spectrum continuity and spectrum contiguity. 6
Crosstalk between adjacent cores Slice 1 Slice 1 Slice 1 Crosstalk Slice 2 Slice 2 Crosstalk Slice 3 Slice 3 None-Crosstalk (a) Crosstalk between adjacent cores Core 1 Core 2 Core 3 XT = h = 2k2 r (1) βw th n n exp n+1 2hL 1+n exp n+1 2hL (2) h denotes the mean increase in crosstalk per unit length. k, r, β, and w th are the relevant fiber parameters, representing the coupling coefficient, bend radius, propagation constant, and core-pitch, respectively. In formulation (2), n is the number of the adjacent cores and L represents the fiber length. (b) Schematic of trench-assisted seven-core fiber 7 (c) Schematic of a core with index trench
Outline 1. Background of SDM-EON 2. Problem description 3. Crosstalk-aware RSCA in SDM-EON. Spectrum compactness in SDM-EON 5. Spectrum defragmentation in SDM-EON 8
Spectrum fragments in SDM-EON But when? How to evaluate it? Spectrum fragmentations 9 Memory fragmentations The issue of spectrum defragmentation will be more serious compared with simple EON, because the spectrum status in SDM- EON becomes more complex. Crosstalk is another factor to be considered with setting a certain threshold value of inter-core crosstalk.
Benefits model of spectrum defragmentation Improve SE Interrupt Service Increase the number of services Reduce the BBR Reduce OEO Reduce the number of transponders N Influence of Spectrum Defragmentation The value of Q represents the benefits of operator Q<0, Spectrum Defragmentation should not been taken; Q>0, Spectrum Defragmentation should be taken. M Quality of Service Q F C E C D C T C P C n F n E i D i T i P n 1 i 1 i 1 Increase the Delay ( * * ) * ( * * ) M Spectrum Energy Delay Interrupt Cost 10
Outline 1. Background of SDM-EON 2. Problem description 3. Spectrum compactness in SDM-EON. Crosstalk-aware RSCA in SDM-EON 5. Spectrum defragmentation in SDM-EON 11
Spectrum compactness in SDM-EON L 1 L 2 Core 3 Core 0 Core 0 Core 0 Core 2 Core 1 Core 1 Core 1 crosstalk Core 2 Core 2 N 1 N 2 N 3 L 1 L 2 SC c,l = S c,l max c,l S min +1 P c,l j=1 B i i=1 SC l 6 = c=0 SC c,l Core 3 G c,l g j c,l G c,l S 1 S 2 S 3 S S 5 S 6 S 7 S 8 S 9 SC 0,1 = 7 2 + 1 SC 1,1 = 9 1 + 1 SC 2,1 = 8 1 + 1 3 SC 3,1 = 7 2 + 1 1 + 2 + 2 3 2 + 3 2 2 + 3 + 1 3 Core 3 = 2.5 SC 0,2 = 7 2 + 1 = 5.625 SC 1,2 = 9 1+1 1 + 1 + 1 + 2 = 5.333 SC 2,2 = 8 1 + 1 = 1.875 SC 3,2 = 7 2 + 1 S 1 S 2 S 3 S S 5 S 6 S 7 S 8 S 9 1 + 2 + 2 3 2+3 2 = 5.625 2 + 2 + 1 3 = 2.5 1 + 1 + 1 + 2 = 3.333 = 1.875 c,l S max c,l c,l and S min represent the maximum and minimum occupied spectrum in the core c of link l respectively. Bi represents the spectrum occupied by the ith connection in the core c of link l.g c,l is the number of available spectrum blocks in the core c of link l, and g j c,l denotes the spectrum resources of the jth available spectrum block in the core c of link l. Xiaosong, Jie Zhang, Yongli Zhao, Jie Zhang, et al., Spectrum compactness based defragmentation in flexible bandwidth optical networks, OFC2012, Los Angeles, CA, USA, Mar.2012. 12
Outline 1. Background of SDM-EON 2. Problem description 3. Spectrum compactness in SDM-EON. Crosstalk-aware RSCA in SDM-EON 5. Spectrum defragmentation in SDM-EON 13
Crosstalk-aware RSCA Request R Calculate k-shortest path For each candidate path, SCs of 7 cores are calculated along each link R is established successfully Select the minimum SC and its corresponding path, core and spectrum segment as RCSA method For each link, sort SC of each core in a descending order Select the core with the maximum SC of each link Spectrum satisfied? N Y Calculate SC Y XT < Threshold N Block the request R SC l 6 = c=0 SC c,l SC = c C,l path l SC before c C,l path l SC after 1
Outline 1. Background of SDM-EON 2. Problem description 3. Spectrum compactness in SDM-EON. Crosstalk-aware RSCA in SDM-EON 5. Spectrum defragmentation in SDM-EON 15
Network model 16
CASD with Same Spectrums and Different Cores The main idea of CASD-SS-DC is to move the connection to another core on the same link with the same spectrum slots to increase the spectrum compactness. 17
CASD with Same Spectrums and Different Cores 18
CASD with Different Spectrums and Same Cores Different from CASD-SS-DC, if there is no available spectrum resources on other cores or the crosstalk exceeds the threshold, the connection can be moved to other available spectrum on the same core along the lightpath. 19
CASD with Different Spectrums and Same Cores 20
Simulation works to be done It is assumed that each fiber has 7 cores and each core has 50 spectrum slots. The fiber parameters k, r, β, w th in formulation 1 are set as 3.16 10 5, 55mm, 10 6, 5μm, respectively, and the threshold for the crosstalk is -32dB. The service requests are generated randomly between any node pairs. The arrivals of service requests follow Poisson process, and the required spectrum of each request is randomly generated between 1 and 5 spectrum slots. The results are obtained from 10,000 service requests. The normal RSA (Nor-RSA) and crosstalk-aware RSA (XTA-RSA) algorithms are simulated as the base algorithms. First fit strategy is adopted in Nor-RSA and XTA-RSA algorithms. The performance is verified in terms of blocking probability, spectrum utilization, spectrum moving times, spectrum defragmentation latency. 21
Thank you for your attention! Yongli Zhao State Key Laboratory of Information Photonics and Optical Communications (IPOC), Beijing University of Posts and Telecommunications (BUPT), Beijing 100876, China Tel : +86-10-61198108; Email: yonglizhao@bupt.edu.cn; Web: ipoc.bupt.edu.cn 22