An experimental LTE setup successfully breached the gigabit speed barrier, with the infrastructure recording a maximum download speed of 1.07Gbps. The recorded data transfer rate translates to a 20 percent increase in maximum attainable download speed and it will also likely correspond to an increase in the average download rates experienced by the subscribers. This test was conducted by the wireless carrier Verizon alongside equipment and infrastructure suppliers Ericsson and Qualcomm. In order to reach this transfer rate, the network had to use carrier aggregation of licensed spectrum coupled with the Licensed Assisted Access technology. The support for the latter protocol allows the network to use unlicensed spectrum to boost the total bandwidth available to the subscribers in a certain area. Choosing LAA over LTE-U also alleviates concerns regarding the possible interference of cellular signals with Wi-Fi connections due to the former’s support for the listen-before-talk feature. This standard checks first whether there is already a transmitter occupying a certain channel before sending its own radio signals on the same frequency.
What is also remarkable with this test is that it only used 3 carriers of 20MHz Frequency Division Duplex (FDD) bands in order to reach the target speeds. In comparison, 3x carrier aggregation can only give top speeds of 600Mbps in supported devices back in 2015. While Verizon may just add more spectrum to improve its network metrics, licensed spectrum is ultimately a finite resource that it shares not only with its rivals but with other companies and even government institutions as well. Thus, it is important for the carrier to improve its spectral efficiency, which is the maximum amount of information that can be transmitted over a certain frequency.
Aside from employing carrier aggregation and the LAA standard, Verizon also used a combination of 4×4 MIMO and 256QAM in order to increase the highest throughput that its infrastructure can achieve. The former technology uses multiple antennas to transmit and receive several data streams at the same time while 256QAM increases the number of bits transmitted over a single transmission. These technologies allowed Verizon to reach the excellent data speeds it had obtained in its testing.