Dynamic Resource Allocationfor Immediate and Advance Reservationin Space-Division-Multiplexing-BasedElastic Optical Networks
Numerous studies have investigated elasticoptical networks (EONs) with the aim of expanding thetransmission capacities of core networks. To achieve thisgoal, it is necessary to solve the spectrum resource wastageproblem caused by spectrum fragmentation. Moreover, dueto the potentially high traffic demands in future networks,it is important to handle requests that need to be reservedimmediately (immediate reservation, IR) as well as thosethat can be reserved in advance (advance reservation,AR). In networks that support the coexistence of IR andAR requests, IR service degradation by AR requests is achallenging issue because AR requests tend to reservefuture resources, which causes a lack of current resourcesto meet IR requests. Therefore, we address the problem ofspectrum fragmentation and the service-level control of IRand AR requests by routing and spectrum allocation (RSA).First, we summarize related research into EONs and resource-allocation methods for IR and AR requests. Next,we propose a novel dynamic RSA method to reduce spectrumfragmentation and control the service level of IRand AR requests in terms of bandwidth blocking probability(BBP) in EONs considering the multiplexing effect ofspatial channels. Finally, we evaluate the proposed methodbased on computer simulations and our results demonstratethat the proposed method can improve the BBPfor the entire traffic flow by reducing spectrum fragmentation,as well as the service control of AR requests and IRrequests under various network conditions.
In networks that support the coexistence of IR and AR requests, IR service degradation by AR requests is a challenging issue because AR requests tend to reserve future resources, which causes a lack of current resources to meet IR requests. Therefore, we address the problem of spectrum fragmentation and the service-level control of IR and AR requests by routing and spectrum allocation (RSA). First, we summarize related research into EONs and resource- allocation methods for IR and AR requests. Next, we propose a novel dynamic RSA method to reduce spectrum fragmentation and control the service level of IR and AR requests in terms of bandwidth blocking probability (BBP) in EONs considering the multiplexing effect of spatial channels.
I n most studies of optical networks, various technologies have been researched intensively to determine ways of coping with exponential increases in network traffic. The elastic optical network (EON) was introduced by Jinno et al. as a promising technology to increase the transmission capacity of optical networks because it can flexibly exploit spectrum resources by selecting modulation formats based on both the requested bit rates and optical reach . This flexibility, based on fine-grained resource provisioning, allows EONs to use spectrum resources more efficiently than traditional rigid wavelength-division multiplexing (WDM) networks. However, despite recent improvements in spectrum utilization by EONs, the future increases in traffic in backbone networks will soon exhaust the expanded
transmission capacity. Space-division multiplexing (SDM) technologies, includingmulti-fibers, -cores, and -modes, have been investigated extensively in an effort to accommodate more network traffic. At the network level, the routing and spectrum assignment (RSA) problem is the most important issue that affects SDM-based EONs, where the aimis to make full use of limited resources.
- N. Dharmaweera, J. Zhao, L. Yan, M. Karlsson, and E. Agrell, “Traffic-grooming- and multipath-routing-enabled impairment-aware elastic optical networks,” J. Opt. Commun. Netw., vol. 8, no. 2, pp. 58–70, Feb. 2016.
- Introduced an ILP formulation to jointly employ traffic grooming and multipath routing considering a realistic physical-layer impairment model.
- Yan, E. Agrell, H. Wymeersch, and M. Brandt-Pearce, “Resource allocation for flexible-grid optical networks with nonlinear channel model,” J. Opt. Commun. Netw., vol. 7, no. 11, pp. B101–B108, Nov. 2015..
- An optimization problem was formulated for RSA to maximize the spectrum utilization and guarantee the quality of signals from the perspective of nonlinear interference described by a Gaussian noise model between channels sharing the same fiber links
We investigated the problem of IR service degradation in EONs that support both IR and AR requests. We proposed two methods to reduce spectrum fragmentation and ensure the service-level control of IR and AR requests. We introduced prioritized areas to reduce spectrum fragmentation by ordering spectrum resources in the frequency domain.In addition, we divided the prioritized areas into IRdedicated and shareable sub-areas, with dynamic control of the border between the two sub-areas in order to control the BBP. We evaluated the proposed methods based on computer simulations.
Concept of the Proposed Method
We propose a novel, dynamic RSA method for reducing spectrum fragmentation as well as controlling the service level of IR requests and AR requests in multi-core EONs. This method configures prioritized areas based on the required frequency slots to reduce spectrum fragmentation. Each prioritized area is divided into two sub-areas: one dedicated to IR requests (IR-dedicated sub-area) and another that is shareable for both IR and AR requests (shareable sub-area). IR-dedicated sub-areas maintain the spectrum resources for IR requests even if the reservations for AR requests increase. Note that we set not ARdedicated sub-areas but shareable sub-areas, because AR requests can be easily allocated compared with IR requests due to flexibility in the time domain. In addition, the border of the IR-dedicated and shareable sub-areas is moved dynamically to obtain the desired ratio for the BBPs of IR and AR requests. Each prioritized area and sub-area follows the same spectrum division in all the cores of the network at all times because this helps to satisfy the continuity constraints on a transmission route in RSA. This method is called AR-limited (AR-L).
We propose another RSA method that configures common areas in addition to prioritized areas to reduce spectrum fragmentation. This method is called AR-Lcommon (AR-L-C). In AR-L, if a prioritized area is fully occupied, overflowed requests are allocated in other prioritized areas. This generates spectrum fragmentation in other prioritized areas, and, subsequently, fragmentation occurs in the area. To cope with this situation, AR-L-C configures a common area in addition to prioritized areas in order to accommodate overflowed requests in prioritized areas. If there is a common area, spectrum fragmentation likely occurs not in prioritized areas but in the common area, which ensures resource alignment in prioritized areas.
- Provide great improvements in terms of the transmission flexibility and capacity.
- Two methods to reduce spectrum fragmentation and ensure the service-level control of IR and AR requests.
- Prioritized areas to reduce spectrum fragmentation y ordering spectrum resources in the frequency domain.
- The proposed methods btained improvements in terms of the BBP, service-level ontrol of IR and AR requests, spectrum fragmentation, and R initial delay.
- System : Pentium Dual Core.
- Hard Disk : 120 GB.
- Monitor : 15’’ LED
- Input Devices : Keyboard, Mouse
- Ram : 1GB
- Operating system : Windows 7.
- Coding Language : MATLAB
- Tool : MATLAB R2013A
Seitaro Sugihara, Yusuke Hirota, ShoheiFujii, Hideki Tode, and Takashi Watanabe, “Dynamic Resource Allocationfor Immediate and Advance Reservationin Space-Division-Multiplexing-BasedElastic Optical Networks”, IEEE 2017.