HOW SDN AND NFV EXTEND THE ADOPTION AND CAPABILITIES OF SELF-ORGANIZING NETWORKS (SON)

Transcription

1 WHITE PAPER HOW SDN AND NFV EXTEND THE ADOPTION AND CAPABILITIES OF SELF-ORGANIZING NETWORKS (SON)

2 WHAT WILL YOU LEARN? n SON in the radio access network n Adoption of SON solutions typical use cases n Challenges when applying SON to the backhaul network n SDN and NFV as SON enablers n Practical applications of SDN/NFV and SON concepts

3 INTRODUCTION Communication service providers (CSPs) are going through rough times trying to reinvent themselves in an age when the network is becoming a commodity. Even though they continue investing in network expansion and quality, network usage is growing rapidly. Therefore, telecom operators are constantly focused on optimizing the utilization of resources in their networks, in order to do more with less. SON IN THE RADIO ACCESS NETWORK SON (self-organizing network) is a set of technologies and concepts that help CSPs to reach that goal by automating network operations. Until recently, SON solutions focused solely on the radio access network (RAN). However, the challenge of network optimization relates not only to access, but also to the backhaul and core networks. Applying the SON concept to other network domains brings its own set of problems. Compared to the RAN, these domains are very heterogeneous in terms of technologies that support them. Network function virtualization and software-defined networking, originally focused on data center networks, have recently been gaining ground in the core and backhaul fields, becoming enablers for the expansion of SON solutions to those network domains. Currently the use of self-organizing network solutions is limited to the automation or assisted management of the radio access network. The first SON solutions were provided by manufacturers of RAN network equipment to help their customers network engineers with network operations. They only worked for equipment provided by one vendor, were usually limited to one or two technologies, and implemented a set of basic use cases. Gradually, RAN vendors provided more configurability, interfaces and software for their products, thus enabling more advanced use cases. This finally opened the door for third-party solution providers to develop SON products that supported a range of vendors and technologies. WHITE PAPER 3

4 ADOPTION OF SON SOLUTIONS TYPICAL USE CASES SON solutions are now widely used, and are being deployed by a growing number of CSPs. The major use cases they support are listed below. n Self-configuration Self-configuration refers to the capabilities of the network to configure its components automatically, in order to provide the desired network services and quality. This can significantly reduce the deployment cost of new cells. Examples include automatically defining and configuring the correct radio transmission parameters, defining and configuring relations between neighboring cells, and keeping an up to date inventory of the network s state and configuration. n Self-optimization Self-optimization refers to the capabilities of the network to optimize itself once it is already operational. Once deployed, networks can be subjected to changing circumstances, such as increased traffic at specific locations or times of the day. The configuration used can then be insufficient to deliver a specific level of service and performance. Some examples include load balancing between cells, optimizing coverage in a specific geographical area, and changing relations between neighboring cells based on actual performance data. n Self-healing Self-healing refers to capabilities to recover automatically from failures or minimize their impact. An example would be detecting a cell outage. The SON solution would then adjust the coverage of the neighboring cells to minimize the loss of service caused by the faulty cell. THE IMPORTANCE OF IMPLEMENTING SON IN THE MOBILE BACKHAUL MOBILE ACCESS AGGREGATION METRO CORE MOBILE BACKHAUL CORE Figure 1. Example of a mobile backhaul topology for mobile access services 4 WHITE PAPER

5 The goal of telecom companies is to deliver end to end services of the highest possible quality at the lowest possible cost. From that point of view, the radio access network is only part of the formula. The value chain for mobile connectivity is also highly dependent on the backhaul and core network. Historically, these have been regarded as more static parts of the infrastructure that do not require continuous optimization. However, this assumption is becoming less and less valid. First of all, CSPs are increasing the density of RAN cells in the network in order to support the increase in data traffic. Deploying new cells requires frequent extensions of the backhaul network and its capacity. Secondly, the portfolio of services that mobile operators are offering is constantly growing and becoming more complex. This complexity is translated into a need for more scalability and flexibility in the backhaul network supporting them. Thirdly, most activities related to these networks have so far been carried out manually, consuming a lot of time and leaving much room for human error. These are exactly the same drivers that pushed the deployment of SON in the radio access networks. Applying SON use cases to the mobile backhaul network will have a similar range of benefits: n Self-configuration functionalities would decrease the number of manual tasks, lowering the likelihood of erroneous configurations and decreasing the time required to deploy the backhaul connectivity. n Self-optimization functionalities would be able to re-configure the mobile backhaul network automatically, to accommodate the changing service traffic patterns. n Self-healing would be able to limit the impact of any incidents in the backhaul network on end to end services. CHALLENGES WHEN APPLYING SON TO THE BACKHAUL NETWORK Looking at academic research and literature, one might get the impression that the automation of network configuration, optimization and assurance is quite straightforward and easy to implement. A lot of the standards developed in the past decade already include self-organizing features in their specifications. Companies such as Google have been running self-sustainable backhaul networks within their data centers for years. So what is keeping CSPs from deploying SON in the mobile backhaul network? n The Complexity of Heterogeneous Networks Backhaul networks have always been deployed to support a specific service offer. This offer has changed substantially in the last two decades. The backhaul network has had to evolve from services based on TDM (time-division multiplexing) in 2G, to hybrid services and finally IP-only services in 3G and then 4G. At the same time, as the radio access networks have to support a variety of configurations ranging from densely populated urban areas to remote mountain valleys, CSPs have used a wide range of technologies (microwave, fiber and copper) to build the most cost-efficient networks. The reality is that the resulting network is very heterogeneous. A SON would thus need to manage a diverse crosstechnology and multi-vendor network. n Lack of Standardization In order for a centralized solution to organize the network, the network must listen to a central controller. Most backhaul solutions currently have their own way of communicating with the network devices. There is no standardization in the communication protocols, data formats or programmability of the network devices. This makes it a lot more complicated to implement SON features for multivendor networks. n The Need for a New Mindset Network engineers have always had a hands-on approach to building and maintaining their networks. Deploying SON solutions will not eliminate these engineers expertise, but will have an impact on how they apply it. They are in general skeptical about the rapid and automated deployment of changes, as they may not be able to keep track and understand the network operations in the same way that they used to. WHITE PAPER 5

6 SDN AND NFV AS SON ENABLERS As described above, there are quite a few challenges related to creating self-optimizing backhaul networks. However, looking at the current trends in the world of networking, there are also many opportunities on the horizon that will help overcome these problems. First of all, CSPs are aggressively phasing out their TDM networks in favor of IP-only networks. Their goal is to create a more homogeneous infrastructure that is cheaper and easier to maintain, manage and automate. Secondly, the standards for future services and applications in 5G and IoT require a flexible, secure, agile and automated networking environment. In consequence, solution vendors are actively investing in deploying technologies that will make self-organizing networks a reality. Two concepts will have a major impact on providing self-organizing functionalities for the backhaul network: software-defined network (SDN) and network function virtualization (NFV). SDN as a Platform for SON Algorithms SDN refers to the collection of protocols, standards, technologies and solutions that enable a network operating system to control the behavior of the network. This network operating system, or SDN controller, will operate as an external control plane, centralizing some of functions that are normally deployed in the network devices. The SDN controller will also implement the protocols and interfaces (APIs) that are required to program the network devices. Various applications can then be deployed on top of the SDN controller and use this API to influence the network behavior. The SDN controller is an enabler for deploying SON in mobile backhaul networks by offering a platform, on which the SON algorithms can be run and deployed. It will abstract the complexity of network and offer standardization of the network programming interface. The SON component on top of the controller will implement the logic that defines the actual behavior of the network. Extending SON Capabilities with NFV Network function virtualization, or NFV, is the extension of IT virtualization to the network space. The goal is to replace purpose-specific physical network devices with generic computing resources running purposespecific software. As the network functions will not depend on a physical device, they will not require a physical installation. New network functions will thus be instantiated, drastically shortening the time to deployment and offering a lot of benefits in terms of scalability. A big limitation of the SON is that it cannot deploy new capacity or network functions in the network automatically, as it requires the installation of new physical devices. By providing an NFV platform with an API to instantiate new capacity or functions, the SON will be able to go beyond optimizing existing resources, and actually scale the resources according to current needs. SELECTED USE CASES Automatic Provisioning and Optimization of S1 and X2 Interfaces As already mentioned, the configuration of essential S1 and X2 interfaces for LTE sites is a very cumbersome process. It requires many manual activities, slowing down the deployment process and increasing the likelihood of errors. For the same reasons, optimizing or making changes to these interface definitions is avoided. 6 WHITE PAPER

7 #1 Mobile Backhaul #2 4GeNodeB x2 Access Router Missing Routing Access Router x2 4GeNodeB 4G-4G Neighbor relation Figure 2. SON for mobile backhaul can automatically detect and provision missing X2 connectivity between enodebs. An SDN controller will be able to give an SON solution the ability to configure and optimize the mobile backhaul network automatically. At the point of deployment, the SON would be able to define the requirements for the S1 and X2 interfaces in terms of capacity and latency. The SDN controller, having an end to end view of the network, will be able to choose the correct route for the interfaces and deploy it to network elements. If one of the interfaces has to change in order to perform a change in a gateway or in neighbor relations, the SON would just update the S1 and X2 requirements for the SDN controller to deploy. It would be possible to carry out this process automatically. Dynamic Bandwidth Allocation Core Site Leased Line Fiber Aggregation Site Fiber Core Site SDH/MPLS Cloud Leased Line Fiber Core Site Leased Line Leased Line MOBILE BACKHAUL CORE Figure 3: SON for mobile backhaul can reprogram backhaul connectivity following changing traffic patterns. Mobile backhaul networks are usually overprovisioned, as bandwidth allocation is done statically. This creates a huge inefficiency in the usage of the deployed resources, leading to increasing costs. As the volume of network traffic increases and its behavior changes, static bandwidth allocation is no longer feasible. WHITE PAPER 7

8 An SON solution will be able to leverage SDN and NFV technologies to implement bandwidth allocation. First of all, when detecting an increase in traffic for a specific service, it can use the SDN controller to re-route the additional traffic through alternative paths, removing the need for overprovisioning the network bandwidth for specific types of services. It may also be required to off-load traffic from specific network components to additional resources planned to be provisioned. If these resources are virtual, they can be easily instantiated by the SON application, and the SDN controller can be leveraged to re-route the traffic to those resources. Once the traffic burst disappears, the resources can be liberated for other network functions that may require them. This concept can also be used in the event of network incidents. HOW COMARCH IS APPLYING THESE CONCEPTS IN PRACTICE Application Layer Business application Business application Business application Business application Controller Layer OSS / BSS Product, customer 360 view Network Service Network Service SON (Customer) Service e2e view Network e2e view Big Data Controller framework Infrastructure layer - Controlled by Open Flow (Open flow) (Open flow) (Open flow) API (Open flow) SDN architecture - vision Figure 3. OSS as a Network Operating System with the SON as a Network function In order to extend the self-organizing network principles to the mobile backhaul domain, SON solutions need to become aware of how this network domain works. First of all, they need to know the network configuration, elements, topology and the services running over the domain. Secondly, SON solutions need to get real time information related to network incidents and performance that impact the service that they are trying to optimize. Lastly, these solutions need to be able to make changes in network configuration. Typical SON solutions are limited to the radio access domain, as extending their compatibility onto other network domains is costly and complicated. The concepts behind SDN and NFV not only simplify the challenges that SON has to overcome to go beyond the radio-access networks, they also extend the possible functionality of SON solutions. So the question is how to deploy SDN and NFV for SON? For SDN, it can be as simple as integrating or developing an SDN-ready controller that supports the various protocols and interfaces. For NFV, SON should act or integrate with the management and orchestration layer of the virtual infrastructure and functions. It s important to consider what that target IT and network architecture would look like and how it would integrate with the current ecosystem? 8 WHITE PAPER

9 CONCLUSIONS Comarch has more than 20 years of experience in deploying OSS solutions that are responsible for operating multi-domain and multi-technology networks. The company has recently extended the solutions for RAN optimization with a selfoptimizing network (SON) solution for radio access networks. In order to implement the use cases presented above, Comarch is leveraging their experience in both domains to define a new OSS architecture that focuses on the strength of the management capabilities in OSS and the network-specific algorithms in SON (see frame above). The core of the architecture relies on the OSS acting as a network operating system (NOS), integrated with the network through various controllers, depending on the network domain. OSS provides its core activities, including inventory, fault management, performance management and activation required to manage each of the network domains. One or more of the controllers is SDN-ready. The NOS manages both physical as logical resources, providing the needed NFV MANO (network function virtualization management and orchestration). In the new architecture SON is deployed as a network function on top of OSS, providing the algorithms and network optimization functions as a main functionality, and receiving all data that it needs from OSS (which will act as the primary data source). Additionally, OSS abstracts the network complexity from the SON application. SON defines optimization proposals, and deliver them to OSS that will be responsible for provisioning them in the network through the appropriate controllers. WHITE PAPER 9

10 CONTACT US Visit for the contact information of our offices in the following countries: Albania Austria Belgium Brazil Canada Chile China Colombia Finland France Germany Italy Luxembourg Malaysia Panama Poland Russia Spain Switzerland UAE UK Ukraine USA ABOUT COMARCH Comarch is a provider of complete IT solutions for telecoms. Since 1993 the company has helped CSPs on 4 continents optimize costs, increase business efficiency and transform BSS/OSS operations. Comarch solutions combine rich out-of-thebox functionalities with high configurability and are complemented with a wide range of services. The company s flexible approach to projects and a variety of deployment models help telecoms make networks smarter, improve customer experience and quickly launch digital services, such as cloud and M2M. This strategy has earned Comarch the trust and loyalty of its clients, including the world s leading CSPs: Vodafone, T-Mobile, Telefónica, E-Plus, KPN and MTS. Copyright Comarch All Rights Reserved telco-enquiries@comarch.com telecoms.comarch.com