Kamran Etemad, Senior advisor, FCC is speaking at the inaugural 5G World Summit, taking place on the 23rd-26th June 2014, at the Amsterdam RAI, Netherlands. Here we find out about his views on making the best use of spectrum and the challenges and opportunities therein.
Unlicensed LTE: surely a contradiction in terms? How does this work and how what problems could it solve?
LTE-U is not a contradiction but a different way of using a technology that is primarily designed to be controlled/managed, in order to leverage the significant amount of unlicensed spectrum, to address exploding demand for mobile data capacity. Depending on how the solution is approached the added complexity may be limited, or large.
Perhaps the simplest and least intrusive way to allow LTE-U operation is to use it as a supplementary carrier to opportunistically expand the effective user plane bandwidth of a licensed primary LTE carrier, which may more predictably carry control plane signaling. The LTE-U supplementary carrier may be configured/activated dynamically through primary carrier for use as a downlink only, uplink only and TDD mode, in an unlicensed or shared spectrum. Some companies are proposing concepts aligned with this approach, while some may be considering a more Wi-Fi-like operation, which requires more changes.
Is shared spectrum a magic bullet for capacity crunch issues?
Spectrum sharing has great potential as it takes advantage of the fact that heavy use of high QoS data may be highly local and temporal. Opportunistic access to a large pool of spectrum can allow statistical averaging of such access at much lower cost. This approach has synergy and can be combined with opportunistic use of licensed and semi/unlicensed carriers to provide a significant boost to effective system capacity.
What are the main practical challenges of making use of shared -spectrum?
Some of key technical challenges are interference management and resource coordination as well as synchronization. There are also some non-technical challenges related to regulation and polices for multi-tier access.
What are the latest developments for use of white spaces for spectrum?
In the US white space devices are being developed but take up is a bit slow as some vendors claim challenging regulatory requirements on RF transmissions and also limited or no WS available in dense markets where demand is the highest.
What predictions can you make on how 5G will use spectrum compared to how it’s used today for 4G?
The evolution of 4G to what is referred to as 5G will need to make best use of all radios and spectra supported on the device and that can be used locally. This includes a combination of a reliable and carefully planned licensed radio access network that can opportunistically find available licensed/shared spectrum and use it to provide the highest data rate and best QoS to users. Such an offering should also take advantage of tighter inter-RAT coupling, e.g. between LTE and Wi-Fi in integrated small cells or CRANs.
Can more be done to encourage spectrum harmonization for today’s networks?
Yes: but making more harmonized spectrum should also take into account the exiting users of the target bands and the diversity of local regulation. While relocating incumbents is always a painful and costly option, smart spectrum sharing with them may be a better and future proof approach that can scale and adopt to local regulations.