Application Level Performance of Carrier Aggregation in a Live LTE Network

Carrier aggregation promises to improve the throughput of Long Term Evolution (LTE) by combining multiple component carriers and sending data over them simultaneously. In this work, we use measurements to investigate the influence of carrier aggregation on the application level throughput and delays of LTE. Our measurements show that carrier aggregation is able to utilize the full capacity offered by the combined carriers. Furthermore, we found that carrier aggregation can improve the delay performance when the link utilization is high, since the additional capacity can be used for load balancing and thus reduce queuing delays. However, when the server sending rate is low, carrier aggregation can lead to an increase in delays, since the carrier with the higher delay will slow down the carrier with the lower delay. In our mobile measurements on a highway we found that the measurements in which carrier aggregation was activated on average achieved a higher throughput and lower delays. However, we also found that carrier aggregation is rarely available in highway areas due to a sparser coverage.