LTE Capacity Planning and PRB Dimensioning: Ensuring Quality of Service in an Increasingly Complex Network
17 SEPTEMBER 2015
RAN networks look very different today than they did in the past – meaning network planners have their work cut out for them.
Complexity, the amount of traffic, and the number of network elements are all increasing – all being exacerbated by HetNets and small cells. Add Wi-Fi and network virtualization into the mix and complexities are on an entirely new level.
With today’s LTE networks carriers rolling out VoLTE, ViLTE, OTT, IoT, and eventually eMBMS, service and product complexity are increasing as well. Consider this with the demands for providing differentiated quality of service (QoS) and the goal of planning and managing a network becomes a bit overwhelming.
Today’s more advanced mobile operators are thinking about customers’ real experiences, instead of taking the more technical view of looking at cell coverage and capacity, and that’s leading network planners towards making some critical decisions about managing limited bandwidth resources. Network planners must remember that the scenario can look good at the high level, but the user experience might be entirely different. Social media creates a lot of cell traffic, and there may be congestion even though the network is well planned. Capacity isn’t an end unto to itself either. It’s not as simple as checking a few boxes and you are done – it’s a constant, ongoing process of fine tuning and optimization, with the end goal of subscribers getting a good, real-world user experience – and of course, this all needs to be balanced with cost.
Today’s LTE network planning goals are to:
- Move network resources to where you need them most
- Reduce costs
- Defer CAPEX
- Generate higher customer satisfaction
- Be able to support new business that is QoS dependent- including IoT services
If funds were unlimited, every operator would have a perfect network with 100% coverage all the time, everywhere. However in reality, with a typical LTE network it will take 5 years before an ROI can be achieved with today’s RAN investments, and Operators need to figure out how to increase real capacity to help stretch their CAPEX dollars. Operators face the law of diminishing returns if they just try to add more cells- hardware doesn’t scale at the macro level. Instead, there is a need to optimize current resources and squeeze capacity out of each cell. Today, CAPEX hardware spend is shifting towards a focus on reducing total cost of ownership and investment by utilizing software tools that can be used to extend the life of current CAPEX investments.
PRB Dimensioning: Helping to Ensure a Quality User Experience while Lowering CAPEX
When it comes to spectrum, with OFDMA, users are allocated a specific number of subcarriers for a predetermined amount of time. In LTE specifications, these are referred to as physical resource blocks (PRBs). PRB dimensioning is becoming increasingly critical, and complex, in today’s LTE networks due to the number of new data-intensive services and bandwidth limitations. When dimensioning a network, planners need to do two things well: 1) forecast traffic and 2) define QoS targets. They need to take into account traffic demands and the various applications in use and support the QoS parameters of each connection over the demanded bandwidth. This is something that will become increasingly important with the Internet of Things and the flood of new content and services that will come with it, much of it with critical KPIs. These all have to be properly managed to ensure users have a good experience.
To fulfill the required QoS specifications of various applications, a number of important parameters must be met, related to issues like bit error rate, jitter, latency and minimum throughput. One of the most useful ways to combat these issues is for planners to look at per-cell coverage. To get this data planners need the right tools to gather critical data, such as overall BH cell data volume, expected service area on a per cell basis, and also traffic density or probability of users being connected at a specific geographical location. All this information is then analyzed together and used to ‘weigh’ the cell’s subscribers based on geographical location.
The challenge is that many of today’s operators are still using outdated Excel based dimensioning tools, which are simply not scalable in today’s environment.
TEOCO’s solutions framework consists of a combination of market leading tools, in-field expertise, and proven processes and methodologies that allow for vendor and operator-specific inputs, targets and resource limits, because every operator’s network is unique.
With the right tools, accurate traffic forecasting and PRB dimensioning can be achieved, thanks to the ability to capture, analyze and visualize critical data through a variety of built-in algorithms, including features like traffic vs. resource distribution based on offered services, and volume based geo-located traffic heatmaps that can be correlated with cell-level traffic data. Cell expansion and optimization tools help CSPs achieve QoS targets and minimize capacity bottlenecks, looking at parameters such as tilt, power, and azimuth, or whether a new site or carrier is required. All available capacity expansion and load balancing options are considered within a single analysis, resulting in the optimal configuration, while minimizing costs required to achieve network capacity requirements. In addition, by performing before/after analysis of the final QoS based on current vs. forecasted traffic profiles, operators can get a better picture of how service quality will impact the user experience on an LTE network.
Understanding element resource utilization, and how this impacts the element capacity limits, and mastering the ability to optimize these limits, and then model and plan for load balancing and/or expansions, are all critical factors in enodeB and cell hardware, license and PRB dimensioning. The ability to map capacity to the network resource management strategy and demand by time of day, type of application, and more, is paramount to ensuring quality of service. There is a lot of data available to help improve accuracy, including linking into other OSS/BSS systems, and dimensioning is just part of the broad optimization picture. By gathering the right data, you not only know what type of service your customers are using, but you can then take that information and use it across other organizations, such as for targeted promotions and marketing. Then when it comes to automatic cell optimization and expansion selection, decisions can be based on a careful cost vs benefit prioritization of planned expansions, so that every dollar is a dollar well-spent.
If you would like to learn more about our approach to capacity planning and dimensioning you can find further information here.