Most experts thought it would require fiber. Karolina Wikander is confident. "Microwave backhaul technology is already able to handle 100 percent of all radio access sites' capacity needs, both now and in the future. By 2020, the technology will have evolved to support multi-Gb capacities in traditional frequency bands and beyond 10 Gb in the millimeter wave."
Most plans for 5G assume extraordinary reliability. The telcos want to control traffic and connected cars. Failures there - including in massive snow or rainstorms - can cost lives. Controlling the cars may require 1 millisecond latency. One expert thought that would be impractical without fiber. (Dan Warren, a good engineer, wonders whether 1 millisecond is practical no matter the technology.) Update - Ericsson pointed out that microwave latency is low. See below.
Millimeter wave high frequency for the 5G network itself is deeply troubling for policy.
It probably requires cell sites every 100 meters or less. That's a heck of a lot of costly backhaul. No one but the incumbent telco has that much fiber most places. While some in policy are comfortable bringing back monopolies (China, Australia, ?Germany,) most in policy have no idea what to do if competition is limited. We all have seen regulation go bad. This may be irrelevant because other market and technologies change will kill most competition anyway, but very few accept that today.
Daisy Dunkley Clark of Ericsson sent me these thoughtful comments.
1. Regarding latency:
Microwave is of even lower latency than fiber. It is always the shortest path between point A and point B, and air is a faster medium than glass. A latency of much below 100 microseconds is fully feasible, as can be seen in the wireless fronthaul section of the Microwave Towards 2020 report. Due to the extremely low latency, microwave is also used in high-frequency trading networks.
2. A few comments on the 5G aspect:
Often there are misconceptions about higher frequency propagation based on extrapolation of traditional building practices and antenna solutions. With smart antenna technologies and scheduling schemes taking into account the full spectrum assets of an operator, higher frequencies can be quite a good complement to support higher capacity demands in densely populated areas (where the capacity need is also the highest).
Also, some of the older propagation models are not doing a good job, something that among others Prof. Rappaport of NYU has shown in this paper, for example: http://nyuwireless.com/wp-content/uploads/2013/12/Path-Loss-Models-for-5G-Millimeter-Wave-Propagation-Channels-in-Urban-Microcells.pdf “The upshot of these new path loss models is that coverage is actually better than first suggested by work in ,  and .”
Ericsson studies on the propagation of higher frequencies, e.g. E. Semaan, F. Harrysson, A. Furuskär, and H. Asplund, “Outdoor-to-Indoor Coverage in High Frequency Bands,” in Proc. of IEEE Global Comm. Conf. (GLOBECOM ), Austin, US, Dec. 2014. (available from IEEE: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?reload=true&arnumber=7063463)
So while perhaps not being a choice for creating rural coverage, higher frequencies, for example around 28 GHz, could be a good complement to lower frequency bands in dense urban environments, in some cases even reusing existing LTE sites. Still, it is important to also try to identify new spectrum bands in lower ranges.
In addition, higher frequencies could be quite useful in indoor deployments and solutions for new use cases for 5G e.g. factory automation etc."
I have updated data from Ted Rappaport on indoor deployments that is very promising. I'll post soon.
Readers with data, help me on this one.
Ericsson: E band spectrum key to boosting microwave capacity
30 Sep 15
September 30, 2015, 16:50 (CEST)
Ericsson (NASDAQ: ERIC) today releases the latest edition of Microwave Towards 2020, an ongoing report series on the state of the microwave business. In the report, Ericsson predicts several major developments by 2020.
Firstly, microwave technology will support multi-gigabit (Gb) capacities in traditional frequency bands and beyond 10 Gb in the millimeter wave (E and V bands). E band spectrum will be key in catering for capacity increases in backhaul as well as fronthaul. In addition, microwave planning will begin to include multiband use.
In the coming years, the choice between fiber and microwave in backhaul networks will not be about capacity, but fiber presence and TCO. Ericsson foresees that microwave will continue to be the dominant backhaul technology. In 2020, 65 percent of all cell sites will be connected by microwave solutions; markets such as China, Japan, South Korea and Taiwan that have existing deep fiber investments will be the exception.
Backhaul media distribution, excluding China, Japan, South Korea and Taiwan
Microwave backhaul technology is already able to handle 100 percent of all radio access sites' capacity needs, both now and in the future. By 2020, the technology will have evolved to support multi-Gb capacities in traditional frequency bands and beyond 10 Gb in the millimeter wave.
Karolina Wikander, Head of Microwave, Ericsson, says: "Microwave networks are a vital ingredient for operators to provide the best possible performance and quality of experience in the most cost-efficient way, and will continue to be the dominant backhaul technology in the future.
"Capacity needs will continue to increase on the road to 5G, and keeping up requires continued technology evolution and re-imagining network efficiency."
E band spectrum will prove key in catering for capacity increases in both fronthaul and backhaul. The E band (70/80GHz) will experience major growth and will represent up to 20 percent of new deployments in 2020. Traditional bands will represent 70 percent of new deployments in 2020.
Ericsson foresees a paradigm shift in microwave planning, with the introduction of multiband use. A seven-time capacity increase can be achieved using a wide, low-availability link in the E band to boost a high-availability link in traditional bands.
New deployment share per frequency range (GHz)
Get more insights - including the pitfalls of the "pizza box" deployment approach and how to save three times the indoor space - in the September 2015 edition of Ericsson's Microwave Towards 2020 report.
This content extract was originally sourced from an external website, Ericsson, on 30
icrowave backhaul technology is already able to handle 100 percent of all radio access sites' capacity needs, both now and in the future. By 2020, the technology will have evolved to support multi-Gb capacities in traditional frequency bands and beyond 10 Gb in the millimeter wave.
Daisy Dunkley Clark