Small Cells Management Strategic White Paper As small cells are introduced into the network, operations and maintenance becomes much more critical. There has to be some sense of total integration between the macro and small cell networks to ensure that smooth operations, quality of service (QoS), and complete integration are realized. To effectively manage interactions within a heterogeneous network (HetNet) a coordinated management solution is essential. This solution is necessary because provisioning, parameter configuration, fault management, alarm management network optimization, and full operations and maintenance must be mutually managed across both small cell and macro base transceiver station (BTS) wireless elements. It is important to recognize that after small cells are installed any changes to the macro network can impact them and vice versa. Traditionally, highly trained personnel are the people who integrate and configure base stations within a wireless network. However, a new paradigm may be required to create the sheer number of small cells that many operators expect to deploy. Because of this, operators should ensure they have an operations, administration, maintenance, and provisioning (OAM&P) approach across both the macro and small cell networks that scale to the level of integration required.
Table of contents Small cells RF planning / 1 Installation and commissioning / 1 Planning and optimization / 1 Assurance and troubleshooting / 2 Conclusion / 3
Small cells RF planning With small cells, traffic localization changes occur over much shorter cycle times making it difficult to use traditional radio frequency (RF) planning approaches. Small cells may even appear and disappear as a result of subscription changes in the case of home cells or enterprise life cycles. This uncertainty makes it difficult to rely on a predetermined, static RF plan. On the contrary, the interference conditions from neighboring small cells will continually evolve, necessitating a more dynamic system of RF planning. For all the aforementioned reasons, OAM&P of small cells and heterogeneous networks brings new types of challenges to wireless operators, specifically within three main areas: Installation and commissioning Planning and optimization Assurance and troubleshooting Installation and commissioning Because of the significant variation that is expected when it comes to deployment and application of small cells, a high degree of automation needs to be present when it comes to provisioning. The extent of provisioning that does exist should resemble that of a Wi-Fi access point or digital subscriber line (DSL) modem and should not require any more manual intervention than absolutely necessary to reduce errors and expedite installation. In the example of home-based small cells that are user installed, processes should mimic those successfully established in the DSL arena. These procedures are based on protocols such as Broadband Forum s TR-069 and are known as zero touch provisioning. In the case of metro cells, the provisioning would fall under selforganized/optimized networks (SON). Small cells should only be required to be physically connected to a power supply and backhaul connection to operate. After they are powered up, they should initiate a connection to the commissioning server that provides authentication and provisions main parameters for the new device, checks for a firmware version, and autonomously triggers software updates as needed. After the device is registered to the wireless network, selfprovisioning of radio access network (RAN) parameters can be automatically initiated, simplifying its integration into the macro network. Planning and optimization Wireless networks traditionally require a large amount of planning long before their actual deployment. This planning includes, but is not limited to, geographical selection of sites; identification and integration of neighboring cells; definition topography; and performing simulation of the RF propagation and traffic conditions. The main site characteristics and parameters are then deduced using sophisticated planning tools and, following verification, uploaded to the base stations through one or more management systems before the cell is integrated and permitted to support live traffic. After live traffic is supported, the next steps are to optimize numerous parameters to ensure user quality and the cell site is successfully integrated into the network. Small Cells Management Alcatel-Lucent Strategic white paper 1
With small cells, the situation is very different. The transmit power of small cells is one or two orders of magnitude less than that of macro cells. In many cases, small cells will often be used to provide indoor coverage or will be very close to each other, making it quite difficult to use traditional propagation considerations. Moreover, the number and position of small cells can vary frequently, as well as the number of connected users and amount of traffic. In these situations, RF planning is of little help, and a dynamic adaptation to external conditions is required to avoid parameter reprovisioning for every site and continuous churn of settings as subscriber density or traffic conditions evolve. With Long Term Evolution (LTE), standards have introduced SON features, such as automatic physical cell identifier (auto PCI) and automatic neighbor relationship (ANR), to facilitate initial configuration and commissioning. However, additional functionality also needs to be considered. For example, devices should be capable of monitoring the surrounding RF landscape to select the optimum primary scrambling code to be used, helping to manage and reduce interference from neighboring cells in the process. Additionally, the transmit power of pilot channels needs to be dynamically adjusted based on the presence of other small cells or changes at the macro layer. With LTE, there are further measures that can be taken to manage interference, such as enhanced intercell interference coordination (eicic) and selective scheduling, as previously discussed herein. It is apparent that a large degree of network autonomy is required in small cell networks to minimize upfront planning and reduce long-term operating expense (OPEX). After the self-planning and installation phase is completed, small cells are then ready for integration into the existing macro network. Assurance and troubleshooting Due to the differing characteristics between small cell applications and environments, validating the quality of experience (QoE) and network troubleshooting can become much more complex. It is imperative that a system of performance monitoring exist within a small cells environment for ongoing benchmarking and reversion comparison. The ability to correlate the level of QoS in a small cells environment to that of the macro layer can be very helpful to provide overall visibility into the perceived QoE and pinpoint any harmful interactions occurring in the network. When dealing with large-scale residential deployments, operation centers must be capable of coping with the simultaneous occurrence of a vast number of events, making new modes of network supervision necessary. Receiving thousands of link loss alarms when residential base stations are switched off could inefficiently overload network operation centers. Because of this, a flexible, configurable alarm reporting scheme with differentiation based on the location, traffic capacity or subscriber grade is necessary to adjust the level of supervision that best fits a specific situation. By implementing event logs within small cells, diagnosis and troubleshooting is still available to help technicians and customer relationship management (CRM) service subscriber complaints in background mode while keeping network operation center resources available for critical situations. This process ensures more efficient use of critical operations personnel resources while still meeting the needs of the individual subscriber. Small Cells Management Alcatel-Lucent Strategic white paper 2
Conclusion As networks become more sophisticated and complex, wireless operators can no longer afford to tune and optimize their networks using manual processes alone. And with the introduction of HetNets, cost-effective, intelligent, next-generation end-to-end network visibility becomes critical. Furthermore, the introduction of small cell networks must be fully integrated to ensure that users achieve the same high quality end-user experience that subscribers have come to expect from the macro network. Ensuring the same level of performance while minimizing OPEX requires the unique characteristics of small cells be addressed in the best manner possible, but within the constraints of existing operations and maintenance processes and capabilities. As such, a self-deploying, selfoptimizing operations, administration, and maintenance (OA&M) functionality is very critical to effectively integrate small cells into existing macro environments. Small Cells Management Alcatel-Lucent Strategic white paper 3
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