The popularity of app services among smartphone users poses a serious challenge to mobile operators: data consumption is soaring; and with an expected 10-fold increase in the next 5 years, investments to merely transfer the sheer amount of data are inevitable. So, how can network operators best address these increasing network capacity and performance demands? Carrier aggregation is one option.

The various macro network enhancements available today offer a cost-efficient and smart approach. To make the most of these investments, however, it is vital to continuously measure the capacity before and after changes have been made – at best with measurement and test solutions that depict capacity and performance from a real end-user perception.

Before exploring the role of mobile network testing in enabling operators to make well-informed decisions about appropriate technologies, this blog series explains in 4 parts the various “smart macro network enhancements” by describing the:

  • fundamentals of the technological approach
  • challenges that operators are facing during capacity enhancement projects
  • tools to support operators with these tasks

The hardware-related capacity enhancing features that will be discussed in this series include carrier aggregation, antenna tilt optimization, 4×4 MIMO, and 6-sector sites (sectorization).

Carrier aggregation

This post’s focus is on carrier aggregation which, without a doubt, today is the most important LTE-Advanced feature. With carrier aggregation, a base station can aggregate 2 or more plain LTE carriers for 1 user in the same (co-located or with a gap in between) or in different frequency bands. The aim is to increase the peak data rate per user. Users may get their data transmitted much faster, so that resources are freed up for others.

Carrier aggregation

Apart from this bundle gain, however, carrier aggregation is not a true capacity enhancement feature. Capacity enhancement, as we understand it, transmits more data over the same amount of air interface resources. With carrier aggregation, the cell capacity is certainly increased, but rather by investing in more spectrum (i.e. more air interface resources).

Carrier aggregation ecosystem

Carrier aggregation is neither a big problem for mobile network testing nor for the base station hardware, since the hardware is often prepared for bandwidths ranging from 40 to 80 to up to a few 100 MHz. It’s more an issue concerning user equipment (UE) categories due to limited chipset capabilities, defined by the 3GPP standard.

The ecosystem for carrier aggregation is quite advanced already: according to the April release of the Global mobile Suppliers Association (GSA) figures, commercially available are:

  • 300 different user devices with up to 300Mbps (UE Cat 6)
  • 40 devices with up to 450Mbps (UE Cat 9)
  • 8 devices with up to 600Mbps (UE Cat 11/12)

The UE categories often provide alternatives in number of aggregated carriers, MIMO schemes (2×2, 4×4), and modulation and coding schemes such as 64QAM or 256QAM. Currently, all these commercial devices (the number is continuously increasing) use carrier aggregation to achieve high downlink data rates.

Rohde & Schwarz mobile network testing supports all major commercially available smartphones as test devices (incl. our QualiPoc Android platform), which support all kinds of carrier aggregation combinations.