Testing a network employing eICIC means that the network tester should be able to apply the relevant UE measurement procedures in order to feedback accurate and reliable information to the network. It is necessary to verify the correlation between the measurements reported by the UE and eNodeB signalling (ABS patterns), verifying the benefits of interference management. eICIC is evolved to “further enhanced ICIC” (feICIC). This increases the cell range expansion of the small cell still further – raising the CRE from 6 dB to 9 dB– by focusing on interference handling by the UE through inter-cell interference cancellation. eICIC and feICIC are especially important when Carrier Aggregation (CA) is not used.
CoMP
Coordinated Multipoint transmission/reception (CoMP) is another major feature of 3GPP LTE-A. Although applying eICIC empowers the mobile network operators to improve overall network capacity, it goes one step further with the addition of CoMP thus by coordinating transmission and reception between different transmitting and receiving cells. It achieves this with the use of load balancing, coordinated scheduling, and with the signal power management and interference management. In the downlink, each mobile terminal sees improved data throughput, especially near the cell edges, due to reduced interference and an increase in the power received. Similarly, for the uplink, received signal quality and cell edge coverage is improved by reception that has been coordinated from different receiving points on the network side.
CoMP requires a rapid exchange of information and the coordination of shared and centralized processing between the multiple transmitting points: eNodeBs, remote radio heads (RRH) and small cells. This is both time-critical and computationally intensive, and requires reports from each UE to be processed for different points in order to make centralized decisions on scheduling and load balancing. These decisions are then rapidly executed to adjust the configuration and the number of points that are active at any time, based on instantaneous channel and interference conditions.
Conclusion
Using a tester with support for eICIC and CoMP, and feICIC interference management techniques can help the mobile operators and vendors to deploy HetNets by emulating and validating realistic usage scenarios. It also allows them to perform trials in the lab and in the field that incorporate realistic performance tests, and thus improve user experience under challenging cell edge and interference conditions.
