As data traffic continues to grow at an exponential rate on mobile networks, followed by the phenomenal rise of smartphone users and other connected devices, the network operators struggle to meet this high demand. Add to it, the depleting spectrum bandwidth. LTE, the licensed spectrum, is limited and as the number of smartphone users increase, bandwidth is rapidly getting congested. This has compelled network operators to explore new opportunities. One such opportunity is the aggregation of licensed LTE spectrum with the unlicensed 5 GHz band being used primarily in Wi-Fi today. The 5 GHz spectrum, by far, has emerged as the most viable spectrum with a huge bandwidth availability. Historically, network operators have been wary of using the unlicensed spectrum. However, in the last couple of years, network operators have started to appreciate the versatility and the potential that unlicensed spectrum offers to serve their subscriber base.
The proposal to introduce LTE in the unlicensed spectrum has sparked concerns amongst long time users of 5 GHz band Wi-Fi vendors and service providers, who are willing to continue without being unfairly penalized by the introduction of LTE. The reason for adopting LTE in the unlicensed spectrum is not to unseat Wi-Fi, but to increase the spectral efficiency and capacity of the 5 GHz band, with a technology that is fully integrated within the mobile operator’s networks. The efficient use of unlicensed spectrum plays a crucial role in increasing resource utilization. Higher bandwidth can be achieved by aggregating the licensed and unlicensed spectrum where multiple technologies will have to coexist for different needs.
There are different possibilities on how the LTE in unlicensed bands can be used. LTE-U and LTE-LAA are the two technology versions of LTE to be used in the unlicensed spectrum. LTE-U relies on 3GPP Release 10 -12 functionality, with specifications defined by the LTE-U Forum. Lacking the implementation of listen-before-talk (LBT) mechanism, LTE-U can be used in markets where regulation does not require LBT, such as China, Korea, India and the USA. From its inception, LTE-U has been designed to coexist with Wi-Fi and other unlicensed technologies on fair grounds. LAA-LTE is the version of LTE unlicensed that 3GPP plans to standardize in Release 13. This version supports LBT. LAA-LTE is set to become a global standard as it strives to meet regulatory requirements worldwide. Due to lack of standardized work, commercialization will take longer time than LTE-U. LTE-LAA provides a globally harmonized solution that leads to better scalability and choice among equipment and device vendors. The LTE-LAA will support LBT (Listen-Before-Talk) and fair co-existence with incumbent players.
The success of LTE and Wi-Fi coexistence will depend upon the relative performance of both these technologies and the efficiency with which performance can be measured. The question that remains is how optimally we can use licensed and unlicensed spectrums to provide higher bandwidth and not affect the performances of the billions of deployed Wi-Fi devices due to LTE Wi-Fi coexistence while measuring the performance efficiently.
What do you think the future of LTE Wi-Fi coexistence holds for the network operators? Please share your comments.
About the Author
Manjunath Kadaba is a Project Manager in Cellular Communications technology vertical at GlobalEdge Software Limited. He has 18+ years of experience working on embedded software and communications in Cellular, Networking and VoIP domain. He is an expert in the areas of LTE & VoLTE. He has also architected & designed Small Cell, VoLTE & EPC solutions at GlobalEdge Software Limited.