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SDN: Optimizing Telecom Networks and Associated Test Challenges

The challenges associated with SDN can be categorized under standardization of control interfaces, security requirements of various network elements such as EPC and RAN, support for heterogeneous networks, support of network slicing and finally cost efficiency.

– Sudhir Tangri, Country General Manager & Vice President, Keysight (India).

The concept of Software Defined Network (SDN) has been introduced to telecommunication industry a few years back. The motivation behind SDN has been to enhance utilization of the network to take it to the optimum level and hence improve revenue/cost ratio for operators. SDN is also needed due to ever-changing cellular technologies from 3G to 4G and now 4.5G so that users are easily provisioned and transitioned from one network type to another.

The services offered by telecom operators in India can be broadly categorized under two main headings, that is, Data and Voice. The data service can be further divided into offerings based on data rates, such as, mobile data, enterprise connections, cloud services, data services to enable cellular internet of things (IoT) etc. Evolution of cellular technology is pushing practical mobile user data rates in India to >50 Mbps. With NB-IoT deployments for machine type communication and new mission-critical services to harness low latency of the network, there is significant requirement for improved traffic management and resource provisioning. We can summarize the drivers for SDN and innovation in network operations as follows:

  • Optimization of network resource allocation
  • Support of sustained higher data rates
  • Power consumption in devices and base stations
  • Lower round trip delays
  • Reducing OPEX and CAPEX
  • Optimization of mobility management policies, scalability, elasticity and agility

This section focuses on various end-user scenarios of the services mentioned above. We start from a regular mobile user who can use legacy networks like GSM/WCDMA for voice and WCDMA/LTE for data connectivity. In urban scenarios, the data consumption is much higher owing to smartphones penetration and affordability and VoLTE services offered by cellular operators. Though this scenario is going to change in coming years as more and more low-cost smartphones reach rural India and network operators extend LTE services in far-off locations. Next set of users are enterprise users who utilize significant network bandwidth and demands for higher QoS. Mission critical users such as financial institutions, hospitals and emergency services demand higher reliability and low latency from the networks. In addition to these user scenarios, the end use pattern of these services varies demographically and with respect to time of the day. For example, in a financial district of a city there will be significant load on the network for both voice and data services during business hours but almost no load during night time. In cities and on highways, there are more and more users utilizing voice and data services while on the move. These use cases demand time-based provisioning, dynamic resource allocation, seamless radio resource management/handovers, improved latency etc.

Figure 1 captures the use cases currently in discussion.

Optimizing Telecom Networks
Figure 1: Various use cases of modern cellular networks

These use cases will not work without redesigning or remodeling of the network topology. This can be achieved without much changes in the hardware setup by having centralized computing engines so that software can react to moving network capacity around the area. Also, the speeds required over the air can be managed by the network. This can help in most efficient use of the network resources including power, spectrum, computing, and data capacity. The network needs to be driven by massive parallel computing platforms which centralizes the way that radio access works. The concepts of radio access network as a service (RANaaS), Cloud RAN and baseband (BB) pooling are fast evolving to address the changing needs of the networks as shown in figure 2.

Cloud RAN
Figure 2: Cloud RAN and RAN as a service

Therefore, SDN has an important role to address these needs using a more dynamic and flexible networking architecture. SDN moves away from traditional architecture and to a revolutionary service delivery platform in which the control plane is accessed and modified using open protocols through software clients. By allowing third parties increased access to the control plane via software, SDN provides enterprises and carriers unparalleled programmability and network flexibility with rapid experimentation and optimization to address changing business needs. Dynamic provisioning of network resources such as cell resizing, cell redistribution, frequency allocation and traffic engineering can be done through SDN.

The challenges associated with SDN can be categorized under standardization of control interfaces, security requirements of various network elements such as EPC and RAN, support for heterogeneous networks, support of network slicing and finally cost efficiency.

With SDN in place, various possible business models may evolve such as pay per use, QoS based charges, assured services for financial institutions and for mission critical users like medical services. These business models would be required to enhance ARPU to offset the cost of implementation for network optimization with SDN and its subsequent upgrades. Operators in India which serve huge density of mobile with low ARPU should make sure SDN benefit is monetized.

Therefore, SDN based network requires successful verification under several provisioned and operating conditions. It requires significant amount of testing in RF and protocol performance. Test pertaining to radio interfaces, performance of network, network visibility, security and capacity need to be performed for SDN-enabled infrastructure for more agile and cost-effective deployments.

Keysight is poised to accelerate innovation to connect and secure the world. Now, with Anite and Ixia products being a part of Keysight, Keysight helps its customers gain insight about how products are functioning at every layer of the stack as shown in figure 3. Keysight can help in testing and validating UE, enodeB, gNb and EPC under different condition network conditions.

Figure 3: Keysight offers workflow solutions for entire wireless ecosystem

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