A novel access integrated system for electric power telecommunication

With the development of diversified communication services in smart grid, user demand and communication capacity have increased constantly, which imposes severe challenges on electric power telecommunication. Especially, the Metro Access Network (MAN) needs to aggregate and exchange a wider variety of services. However, metro and access networks developed independently, thus consuming a lot of network resources in complex infrastructures, which increases the development and operational costs of network operators. To address these problems above, we propose and demonstrate a novel metro-access integrated network based on Intensity Modulation and Direct Detection (IM/DD) Orthogonal Frequency-Division Multiple Access (OFDMA) techniques. It consists of a single fiber ring and many single fiber trees, and transparently integrates metropolitan area networks with optical access networks. The single fiber ring connects core networks and Central Nodes (CNs) which can allocate subcarriers according to user demand. Meanwhile, they can also implement flexible power distribution. The Remote Nodes (RNs) distributed on the user side are connected with the corresponding CN through the single fiber tree. Simulation results indicate that our proposed metro-access integrated network is feasible for electric power telecommunication while ensuring agile power distribution. Introduction With the increasing demand for emerging services in smart grid, the bandwidth requirement for access network is rising dramatically, leading to the increasing number of end users. Meanwhile, a large number of different communication methods need to be integrated and exchanged in metro networks. The access capacity will be soon put in a tight spot since the throughput capacity of metro networks is limited. Furthermore, the metro network and access network develop independently for current electric power telecommunication, which consumes a large amount of infrastructures and energy [1-3]. As a result, the integration of metro and access networks has gained great research interests. Especially, the long reach Passive Optical Network (PON) which is connected to the core network directly has become the best choice to meet this requirement. Besides, Orthogonal Frequency Division Multiplexing (OFDM) based PON has been widely studied since it is spectrum-efficient and flexible in bandwidth allocation [4]. The long reach PON has a ring-based topology, while the access part utilizes a tree-based topology. Thus, the existing long reach PON exhibits the characteristics of simple scalability, renewability and high bandwidth. There are two structures for metro-access integrated networks. The first one is an advanced scalable passive access network proposed by European researchers. In this structure, a passive add/drop remote node is used for the connection between Wavelength-Division-Multiplexing (WDM)-based two-fiber path ring and Time-Division-Multiplexing (TDM)-based single fiber tree. The other one is the metropolitan access ring integrated network. The two modes mentioned above share the infrastructures and information rate through TDM and WDM techniques. However, TDM requires strict time synchronization, while WDM needs expensive tunable lasers to satisfy the 6th International Conference on Information Engineering for Mechanics and Materials (ICIMM 2016) © 2016. The authors Published by Atlantis Press 25 bandwidth demand of end users. Apparently, the aforementioned access methods are complicated or expensive. In contrast, the optical OFDM is a promising candidate solution for access networks since it has the advantage of high spectrum efficiency, strong tolerance of fiber dispersion and flexible bandwidth allocation [5]. In this paper, we propose a metro-access integrated system based on OFDM technique and demonstrate its feasibility successfully. In the proposed system, the single fiber ring is connected with a single fiber tree through Central Nodes (CNs) which achieves the communication routing. Moreover, the integrated network can improve system capacity and flexibility since new CNs can be set according to the user demand. The remainder of this paper is organized as follows. In section 2, we introduce the proposed metro-access integrated system. The simulation setup and results are shown in section 3. Finally, we conclude this paper in section 4. Metro-access integrated system for electric power telecommunication Generation of electrical OFDM signal. Based on the OFDM transmitter mentioned in [4], we introduce sub-band division in our system, which means that the sub-band carries information for different end users. Sub-band division is performed before Inverse Fast Fourier Transform (IFFT) module. Zero padding which is treated as guard-band between different sub-bands is executed between a certain number of data-carrying subcarriers. Figure 1 shows the multi-band OFDM signal spectrum. Band 1 Band 2 Band 3 Band n Frequency Guard-band CO CN1 CN2