A Generalized SDN Framework for Optical Wireless

A Generalized SDN Framework for Optical Wireless Communication Networks Md. Shahjalal*, Mostafa Zaman Chowdhury, Moh. Khalid Hasan, Md. Tanvir Hossan, and Yeong Min Jang• Department of Electronics Engineering, Kookmin University, Seoul, Korea Email: *[email protected], •[email protected]

Abstract— Wireless communication based on optical spectrum has been a promising technology to support increasing bandwidth demand in the recent years. Light fidelity, optical camera communication, visible light communication, underwater optical wireless communication, free space optical communication are such technologies those have been already deployed to support the challenges in wireless communications. Those technologies create massive data traffic as lots of infrastructures and servers are connected with the internet. Software defined optical wireless networks have been introduced in this paper as a solution to this phenomenon. An architecture has been designed where we provide the general software defined networking (SDN) structure and describe the possible tasks which can be performed by the SDN for optical wireless communication. Keywords— Software defined networking; Optical Wireless Communication; VLC; LiFi; optical camera communication.

I.

INTRODUCTION

Optical wireless communication (OWC) refers to the wireless communication through the optical spectrum. The recent fifth-generation (5G) technology is characterized with ultra-high security, capacity, ultra-low latency and power consumption, and massive connectivity of physical devices [1]. To support the ultra-high demands for 5G, OWC will play an effective role by reducing the load on the limited radio frequency (RF) band of the electromagnetic spectrum. OWC applications comprises of different networks such as visible light communication (VLC), free space optical communication (FSOC), light fidelity (LiFi), and optical camera communication (OCC) depending on the spectrum, types of transmitter and receiver being used [1]- [3]. These OWC technologies can provide low to high range data rate services and ultra-short range to ultra-high range communication links [1], [4]. With the development of OWC based appliances it becomes a major issue to be considered controlling all the networks centrally. Which can provide much better network management, load balancing, packet traffic management, enhancing security, and network flexibility. Software defined networking (SDN) can be the expected solution to the aforementioned challenges as it has such properties [6]. SDN system reduces the working load from the network devices (switches and routers) and only allows them to perform data forwarding functionalities. A centralized control

plane is built decupling from the data plane. As a result, most of the functions which consumes higher amount of energy are removed from the infrastructure layer and delivers better flexibility which is also the key requirement of dense OWC networks. Areas of researches including SDN-based technologies are increasing day by day. Researchers have already kept their eyes on SDN based internet of things (IoT), wireless sensor networks (WSN), vehicular access network (VANET), 5G etc. In [7], authors describe the requirements and challenges of IoT system that can be fulfill by the SDN-based technologies from different networking aspects such as edge, core, access and data center networking. There are lots of researches on the issues of energy, network management and configuration, routing, scalability and mobility enhancement challenges of WSN which can be potentially solved by the SDN base approach [8]. In [9], [10] authors proposed a reliable and low latency communication in software defined VANET structure. Also Higher throughputs and energy efficient LTE network performances can be found using SDN enabled 5G technology [11]. In this paper we have designed a generalized framework for SDN enabled OWC networks and described about the potential solutions which can be performed by the SDN-based approaches. The rest of the paper is arranged as follows. In Section II, we describe the general SDN structure and interfaces. An overview of proposed Software defined optical wireless networks (SDOWC) is described with potential solutions in Section III. Research challenges, future works, and conclusion are discussed in Section IV. II.

OVERVIEW OF SDN

Recently, SDN draws considerable amount of attentions in researches, industries which have been resulted in much deployment and evaluation of it. In this section, we will give a brief overview of SDN technology. A. SDN architecture SDN is an emerging concept which mainly focuses on the network management by separating the control functionalities from the data plane. It offers a high level network abstraction apart from traditional network architecture where network devices accomplished both controlling and data forwarding [8]. SDN architecture typically consists of three separate planes as depicted in Figure 1. The first one is the application plane which connects various SDN based applications and have interfaces between them. The second plane is control plane which performs in a centralized manner. The SDN controller

Application layer application 1

……………

application m

has laggings to control trunk interfaces and queuing, has some poor network status on communication management, and absence of such specific methods to link between controller and switches [6].

Northbound API interface

Control layer Controller Southbound API interface

Infrastructure layer node 1

……………

node x

Figure 1: Generalized SDN structure and interfaces.

receives the instructions depending on the types of application requirements and relays the command to the routers or switches. The controllers also find out the network views and manage the signage traffic and extracts the network statistics. Data plane (infrastructure plane) is the third layer which consists of networking devices that performs only the data forwarding activities. Different application programming interfaces (APIs) are connected between the planes to communicate each other. By the southbound (SB) interface, control signal is carried out from the control plane to the infrastructure plane. SB interface accommodates greater flexibility in control plane so that it can adopt newly developed control methods [6]. Whereas, northbound (NB) API is connected for the communication between application plane and control plane. Through this API, programming can be done to perform such complex tasks like traffic engineering topology discovery, quality of service (QoS), load balancing, security tasks, delay management etc. Eastbound and westbound APIs are responsible for interfacing between the control layers for taking the coordinate decisions [6], [8], [12]. B. Standards and protocols SDN has to follow some protocols and standards to build higher control networking in between heterogeneous networks. Currently, researches are investing their efforts on standardization the protocols for the SDN interfaces to do different tasks. The southbound interface uses protocols like Forwarding and Control element separating (ForCes), OpenFlow, Protocol Oblivious Forwarding (POF) to update the routing table entries in network devices [13], [14]. Therefore, ForCes and OpenFlow are the two most popular specifications and both depend on the principle of data and control plane decoupling. OpenFlow is more common than the others and it was developed by the Open Network Foundation (ONF) [8]. It enables the controllers to control more sophisticated traffic management and routing protocol. However, for northbound interface there are not much established standards existing because it depends on the network operator’s choice of controllers. Though OpenFlow offers some intellectual contributions, still it is not considered to be a complete standard because of some imbalance between practicality and generality. In short, it

C. Functionalities SDN technology already spreads its benefits in various aspects such as managing heterogeneous networks, controlling data traffic, ensuring security, and mapping resource distribution. SDN is recently applied on different campus networks as it is so dynamic and network policies changes over time. It is also being used in wide-area networks (WAN), software defined radios, cellular networks, cognitive radios, and wireless sensor networks [6], [12]. The key functionalities of the SDN for wireless networking can be summarized as: · · ·

· ·

Saparateing control commotion from the intrustructure layer. Enableing more centralized control and improves dynamic routing. Guideing the network to a desired operating condition by enabling graceful evaluation of protocols. Helping to deploy new protocols without replacment of the data plane switches. Simplifying the design of switches and routers as they become dedicated only to the packet forwarding. III.

SDN INTEGRATED OWC

OWC technology currently spreading its uses into different categories such as smart home, industry, smart health care, intelligent vehicle, underwater, and free space [1]- [5]. In all these systems, optical sources transmit data and photo-diode (PD), camera or optical sensors receives the data. Lighting servers which are connected to the OWC systems through internet serve the required data. In real-time applications, information to the data servers should be monitored and regulated efficiently. But with the development OWC technologies massive devices are connected and generate huge data traffics which reduce the device efficiencies and increase communication latency [1]. Also we need to think about the routing and network management, resource management, security, scalability and energy requirements challenges for the densely deployed OWC networks. We have illustrated a generalized SDN-based OWC networking framework depicted in Figure 2. In this scenario, the OWC networks such as VLC, OCC, LiFi, UOWC, FSOC comprise in the infrastructure layer gets the packet forwarding commands from the control layer passing through the network devices (routers, switches). Here, in SDN controllers perform several tasks like updating flow protocol, function generation and program the interface. The application layer comprises of different tasks depending on the network demands such as traffic controlling, security management, network flow management etc. In this section we discuss about the key requirements of OWC system which can be satisfied by SDNbased technologies.

Application layer ………… Security… management

Traffic controlling

Network flow management

Northbound API interface Control layer Update flow protocol

Function generation Programming interface Southbound API interface Infrastructure layer Routing infrastructure

node 1 VLC

node 2 FSO

node 6 node 3 Li-Fi

node 4 UOWC

node 5

NLOS UV

OCC

Figure 2. The proposed generalized framework for SDN-based OWC networks.

A. Data acquisition and routing With the recent development of OWC applications there are increasing number of connected devices and infrastructures. Therefore, massive amount of data is generated and which need to manage and process efficiently [1], [5]. For this type of applications data need to monitor continuously or regularly. Consequently, an adequate network solution is required to control the data processing and route them properly. Different types of OWC technologies need to connect together and control centrally. SDN-based technology can be the perfect solution in these case as it can control the network in a centralized manner. B. Energy management In OWC system huge number of data providing servers are involved in processing high amount of data volume. For example, data servers are used for VLC-based smart patient monitoring systems to regulate necessary medical data and patient health information. There have such other data centers used for vehicle-to-vehicle, vehicle-to-infrastructures [15] and underwater optical wireless communication (UOWC) technologies. Therefore, huge amount of energy will be required for these data servers. SDN technologies can be implemented for the purpose of energy consumption reduction by controlling data traffic. Thus the devices at the data providers can be switched dynamically based on the requirements which establish an energy efficient networking. C. Ensuring security While lots of user devices and servers are connected to the network and devices security is an important issue. In accordance to the service providers they have controlling devices send requested data to the user and receives data from

different users as well. Due to the installation of various devices in every platform of OWC networks providing security and ensure the privacy become complex. As SDN technology divides the data plane from controlling the data routing and other accesses it will be easier to the way of securing the whole OWC systems. D. Virtualizing network functions The concept of network function virtualization is to diverting the traditional network controllers doing real-time tasks and also performing multiple accesses over the networks. With the development of recent OWC applications it is required to perform real-time tasks as well communicate with multiple users. Consequently, the approach based on SDN will draw an essential part to understand the concept of virtualizing network function. Also resources can be allocated in an efficient way among the different OWC technologies to increase the network performance. Proposed SDOWC technology can map the resource distribution system automatically with the demand. IV.

CONCLUSION

In this paper, we make a functional and architectural overview of SDN and study about the SDN capabilities which can be integrated in case of OWC networks. The recent massive deployment of OWC networks require more efficient networking through ad hoc networks, better traffic management, reduced communication latency, improved scalability, and network security to enhance the network performance. We present an SDOWC framework in this paper integrating different outdoor and indoor OWC networks which can fulfil the demands and offers better flexibility over the network controlling.

ACKNOWLEDGMENT This work was supported by the Technology Innovation Program (or Industrial Strategic Technology Development Program-Development and dissemination of national standard technology - Development of national standard technology improvement technology) (20002348, To enhance the safety function of vehicles international standardization of CALMOCC for V2X technology and national standardization of functional safety standards) funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea)

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