Elastic optical networking is an attractive technology for the next generation of backbone networks, because it can flexibly provide spectrum resources to connection requests. In elastic optical networks, spectrum resources are generally split into frequency slices with finer granularity and each connection request can use several frequency slices according to its bandwidth requirement. In the process of spectrum assignment, numbers of frequency slices used by different connection requests are diverse, which may lead to misalignment of frequency slices in different links. The misalignment would affect the effective use of spectrum resources and result in the increase of blocking probability of connection requests. For the purpose of reducing the misalignment of frequency slices and thereby decreasing the blocking probability, we propose a prime-partition strategy for the spectrum assignment problem in this paper. The strategy partitions frequency slices in each link into prime blocks with sizes equaling prime numbers 2, 3, 5, 7, etc., and the prime blocks with the same size are aligned in different links. After the partition operation, each connection request can be served by one or more adjacent prime blocks with the same size, no matter how many frequency slices it needs. Based on the prime-partition strategy, we design a novel spectrum assignment algorithm in which the enhanced-most-used policy is used to break ties. The enhanced-most-used policy can make idle prime blocks more aligned in different links. Simulation results show that the prime-partition-based spectrum assignment algorithm outperforms the existing well-performed algorithms in terms of blocking probability.

弹性光网络是下一代骨干网的一项有吸引力的技术，因为它可以灵活地为连接请求提供频谱资源。在弹性光网络中，通常将频谱资源分成具有更细粒度的频率片，每个连接请求可以根据其带宽要求使用几个频率片。在频谱分配过程中，不同连接请求所使用的频率片的数量是多种多样的，这可能导致不同链路中的频率片未对准。该未对准将影响频谱资源的有效使用，并导致连接请求的阻塞概率增加。为了减少频率片的未对准从而降低阻塞概率，在本文中，我们针对频谱分配问题提出了一种主分区策略。该策略将每个链路中的频率切片划分为大小等于素数2、3、5、7等的素块，并且具有相同大小的素块在不同的链路中对齐。分区操作后，无论需要多少个频率片，每个连接请求都可以由一个或多个相同大小的相邻素块提供服务。基于素数分割策略，我们设计了一种新颖的频谱分配算法，其中使用了最常用的增强策略来打破平局。增强型最常用的策略可以使空闲的主数据块在不同的链路中更加对齐。