Can small cells meet the growing demand for mobile broadband services?

Toni Pellegrino SA
Toni Pellegrino, Head of Sales, Southern Africa and Vodafone Market Unit, Nokia Networks.

Be it developed telecom market or developing one, Small cells offer a cost-effective way to meet the growing demand for mobile broadband services, complementing conventional macro capacity. However, operators need to set the right strategy to ensure they are getting the right cells, at the right cost, in the right locations.

Major South African operators and internet service providers (ISPs) have now started considering small cells deployments seriously. Small cells will change the landscape of the radio networks here and provide significantly improved network capacity, speed and coverage for a world-class voice and data services.

With more and more people using smart devices and sophisticated apps, demand for mobile broadband is growing almost exponentially. Data-hungry mobile services such as video, enabled by powerful new devices with integrated cameras running new apps, are further fuelling the growth. Cloud technology will also drive up mobile data volumes, while the machine-to-machine market is expected to have a substantial impact on networks within the next few years.
Small cells complement existing macro network

Small cells offer a cost-effective way to meet the rapidly increasing demand for mobile broadband services, especially in large and complex indoor areas, and they offer a better, faster user experience from a lower power, lower cost site. Setting up a new macro site is extremely difficult, costly and very time consuming. In contrast, micro and pico cells can be deployed on non-traditional sites and require much less space.

The latest small cell base stations support the most commonly used frequency bands for FDD-LTE and TD-LTE and are used for deployment in outdoor and harsh indoor environments. New public indoor pico-cell base stations also integrate LTE and Wi-Fi in one unit and can even use a building’s existing shared Ethernet cabling for backhaul, eliminating the cost of installing new wiring typically needed for Distributed Antenna Systems (DAS).

Software and feature parity between macro and micro/pico cells is one of the critical steps needed in small cell deployment. It will help create tighter integration with the macro layer, with improved HetNet performance, better coverage and a consistent user experience.

Planning a small cell network
An operator can choose to use a blanket approach or to surgically insert individual small cells exactly where additional coverage and capacity is needed.

While initially expensive, blanket approach may be chosen to provide best end-user experience, lowest planning effort and best solution for indoor users. Today’s ‘hot spots’ of high traffic at a particular location are expected to grow into larger and denser ‘hot zones’, where a blanket approach is the only solution.

A more refined surgical approach that adds coverage and capacity exactly where it is needed calls for an integrated network management framework for small cells. This could generate plans showing capacity hot zones and hotspots based on user activity and network statistics. All available small cell solutions could be evaluated together, and matched to factors such as site accessibility and backhaul options.

A smart location approach is needed. Considering device type, apps used and the typical hot spot analyses, planning and optimization tools with 3D geo-location are deployed during and after the deployment to guarantee the best customer experience.

Delivering indoor coverage
Small cells offer new options for operators to provide better indoor coverage and capacity. For large indoor high capacity areas such as airports, shopping malls and high rise buildings, indoor small cells typically provide significantly better capacity with similar coverage to a DAS.

The cost of the radio equipment is higher for indoor small cells compared to the DAS radio but the deployment, installation and other CAPEX are significantly reduced, creating a very attractive business case for indoor small cells. In addition to the equipments, Nokia has developed a lean execution for small cell to reduce deployment time from days to hours. Activities are clustered, and performed at the same time for efficiency.

The role of Wi-Fi and traffic steering
The addition of carrier Wi-Fi to a small cell site can increase the number of satisfied users by typically 20-25%. It simultaneously offers a service to new Wi-Fi-only customers and functions as an effective bridge to support the traffic of most 3G and LTE smart devices.

Balancing the total mobile broadband load between 3GPP and Wi-Fi requires Wi-Fi–3GPP traffic steering. A rules-based method of traffic steering is achieved with the Access Network Discovery and Selection Function (ANDSF), which is a standardized way for operators to balance the load between networks. The solution based on ANDSF lies in automated creation of traffic steering rules, which can save operators substantial manual work and achieve the highest network utilization.

Mass deployment depends on the right transport network
Operators and vendors generally agree that mass deployment of small cells will be affected by the availability of cost-effective backhaul solutions. Small cells will more than likely require several flexible transport options to suit the needs of each operator and area. As an example, whether wired or wireless backhaul is most suitable will depend on the evolution of both technology and market and operators will need to make use of options in both these domains.

NPO: Network Planning and Optimization
NI: Network Implementation
SI: System Integration
MS: Managed Services
Care: Third Level Support

The power equation
The power needed for small cells is also a factor when planning the network. Quite simply, the larger the coverage area of a cell, the more user devices it attracts.

Detailed 3G and LTE deployment studies indicate that using a fairly high output power for outdoor small cells (5W per antenna, or the highest levels below rooftop power levels) yields improved TCO in sparse deployments. For small cell blanket deployments, or where capacity is needed mainly for outdoor users, 1-2 W deployments appear to be the most cost-efficient.

Caption: Example of a deployment of five small cells along a shopping street in a dense urban area with 80m Inter-site Distance (ISD). Each cell transmits with 37dBm and provides blanket coverage both indoors and outdoors. For denser or hotspot deployment, 30dBm provides sufficient coverage

So, small cells cannot simply be considered as low-powered macro cells. In effect, outdoor small cells bring many unique factors which strongly influence the selection of an appropriate small cell solution for a specific location.

It is very important to establish the value of a small cell (or small cell cluster), ensuring it serves a sufficiently high number of end-users to justify the investment. This is done by getting a clear and precise understanding of where the operator’s traffic is, requiring a new set of tools for hotspot/hotzone identification and planning.

The deployment strategy, including selection of radio parameters such as power levels, spectrum and access technology, has a significant effect on the TCO, mainly in how many subscribers are effectively served by an installed outdoor small cell site.

By Toni Pellegrino, Head of Sales, Southern Africa and Vodafone Market Unit, Nokia Networks