There are significant variations between the EU and the US when it comes to the 60GHz band – and the rest of the world, for that matter.
One of the most visible difference is the channel’s boundaries, with the US, Canada and Korea all running it between 57 and 64GHz to give seven GHz of bandwidth. Japan similarly delivers 7 GHz of bandwidth, but uses 59 – 66 GHz. China uses a 5GHz band from 59 – 64 GHz. And the EU delivers 9 GHz of bandwidth, from 57 to 66 GHz.
These are subtle variations, but demand that chips will require a degree of software configurability if they are to fully exploit the full bandwidth in each region and realise an economy of scale by deploying the same chip in each region.
But that’s not the complete picture and a more interesting consequence can be seen when we look at EIRP (equivalent isotropically radiated power) transmitter regulations, instead. Here, the US is regulated by the FCC 15.255 regulations and the EU deploys CEPT REC(09)01 supplemented by ETSI EN 302 217.
The baseline for EIRP limitations for operation in the US, under FCC Part 15.255, is +40 dBmi – with the potential for trade off of conducted power (up to 27 dBm) and antenna gain within that upper limit… we’ll come back to this.
Moreover, in August 2013 the FCC ruled that outdoor link operation between fixed points could use an even higher EIRP, up to a maximum average power of up to +82 dBmi (minus 2 dB for every 1 dB that the antenna gain is less than 51 dBi). Thus increased EIRP above +40 dBmi is possible for 60 GHz fixed wireless systems using high gain antennas with a gain of +30 to + 51 dBi.
This compares with Europe’s 55 dBmi. But, whereas the EU CEPT 09(01) stipulates a minimum gain greater than 30 dBi and a maximum power of less than +10 dBm, the FCC’s regulations allow a gain and power trade off within the same +40 dBmi average EIRP limit.
This trade-off between gain and power allows for the use of lower cost active phased array antennas for 60 GHz wireless backhaul. This technology is coming to market to as a consequence of the larger wireless consumer electronics market, which is emerging for 60GHz WiFi market under the ‘WiGig Certified’ programme.
Whereas, for companies deploying backhaul networks intended for operation in Europe the current regulations lead to the use of mechanically steered high gain antennas (> +30 dBi) with custom modems (power < + 10 dBm). This traditional approach is both more expensive and less flexible than the use of active 60 GHz phased array technology. And as a consequence this increases the equipment costs seen by EU mobile operators – typically more than $8,000 per 60 GHz link (~£5000, ~€6000).
This can be compared to the US market, where FCC rules support the full use of active phased array technology which has the potential to deliver such links at cost points below $1,000 per link (~£600, ~€700) – with the added benefit of auto-installation and tracking over wide coverage angles.
In 2010 Eric Schmidt (then CEO of Google) famously said: “Every two days, we create as much information as we did from the dawn of civilisation up until 2003.” Cisco currently predicts that 1.4 zettabytes (1021 bytes) will flow over global networks by 2017.
And herein lies the problem. Today’s average backhaul capacity is 35 Mbits/s per cell. This needs to increase to 1 Gbit/s per cell in just five years to support the predicted mobile data growth that will arise from the switch to 4G and the consumer demands for video streaming over the mobile network.
As a result, LTE operators anticipate that more than half of their annual capital expenditures will be allocated to meet this demand, using smaller cell sizes… with the Small Cell Forum estimating the need for up to 72,000 small cells to support mobile traffic growth in London alone.
And since the outdoor operation of WiGig consumer electronic devices – mobile phones and tablets – will already violate EU CEPT REC(09)01 rules, we need to ask why we are constraining the application of phased array technology for backhaul in Europe?
With this in mind, it is likely that the current regulations for the 60GHz band are redundant and will limit network capacity in the EU? We suggest, therefore, that there is an urgent need to review and harmonise the EU’s 60GHz radio regulations with the US’s in order to stimulate the deployment of low cost 60GHz wireless backhaul in Europe.