If fifth generation mobile networks supply 10 Gbps of bandwidth for every user or device, then even using all other available techniques--multiple input, multiple output radios, directional and phased array antennas, beamforming, ultra-dense small cell networks, better semiconductor technology, signal polarization and dynamic spectrum access--lot of new spectrum will be required.
To give you some idea of what eventually will happen, the regional allocation for mobile services now is about 500 MHz, in total. For 5G, allocations are expected to be in the 10 GHz range. In other words, two orders of magnitude more bandwidth is expected to be allocated, but most of the growth will come from use of small cell architectures.
Some think as much as two orders of magnitude effective spectrum use will come from small cell architectures, about 20 times improvement from additional spectrum and maybe twice as much effective use will come from all the improvements made possible by Moore’s Law.
But there is lots of room for surprise. Some think the present limit of about two bits per Hertz of bandwidth could grow to 10 bits per Hertz or even 30 bits per Hertz, effectively. That would be a stunning advance, indeed.
In that regard, Ofcom, the U.K. communications regulator, has identified the millimeter wave bands it believes are best for fifth generation (5G) networks, and especially suitable for early discussion at the upcoming World Radio Conference.
“Our preliminary view is that the frequency bands 10.125 to 10.225; 10.475 to 10.575 GHz; 31.8 to 33.4 GHz; 40.5 to 43.5 GHz; 45.5 to 48.9 GHz and 66 to 71 GHz should be considered for study under a focussed agenda item on 5G mobile broadband for WRC-19,” Ofcom said.
At the moment, Ofcom says, there is general consensus that immediate efforts should be focused on additional spectrum below 100 GHz. Satellite interests generally argued that new allocations should be made at above 30 GHz, to avoid interference with existing satellite operations.
“We think these bands may be relatively straightforward to make available in the UK
compared to other options within the range 6 to 100 GHz...and could have potential for being harmonised and developed for future 5G use globally,” Ofcom said.
Spectrum adjacent to these bands, such as around 10 GHz, 43.5 to 45.5 GHz and 71 to 76 GHz and 81 to 86 GHz also are worth examining, Ofcom said.
To give you some idea of how much spectrum might be feasible, consider that Ofcom said
“it is particularly difficult to identify bandwidths of least 1 GHz below 30 GHz taking
account of incumbent use of these bands.” In other words, Ofcom is looking, ideally, at allocations of at least 1,000 MHz per band.
Ofcom also points out that several different technology solutions will help enable use of spectrum above 6 GHz to enable 5G.
Those solutions include massive multiple input, multiple output radios, directional and phased array antennas, beamforming, ultra-dense small cell networks, better semiconductor technology, signal polarization and dynamic spectrum access.
