Will 5G Improve Cellular Performance So It’s No Longer An Embarrassment?

11 Jun 2018

I love radios. Ever since I saw that first backpack walkie-talkie on the Combat TV series back in the 1960s, or the push-to-talk radios (with telephone-style handsets) in NYPD squad cars, I was hooked on radios. But early on I was introduced to the cruel trade-off with radio: it’s marvelously convenient, it can be a potential lifesaver, but you can’t count on it working well (or at all) some part of the time.

To be clear, designers and engineers have done a spectacular job at improving the overall efficiency (i.e. how much radio spectrum they require for each task) and reliability. Among those reliability improvements we can count better signal encoding, MIMO, forward error correction (FEC), beam forming and a bunch of other more subtle changes. However, you still can’t count on radio.

In defense of the technology, radio is just tough to do. Think about it. We are sending waves of electromagnetic energy that nobody can see or feel through free space, detecting it up to several miles away (much farther if we’re using a satellite), amplifying, correcting (that’s what “FEC” is about) and finally decoding the information so someone can see it or hear it. When you think about it, why should that work?

All the time we’re doing this with higher and higher frequency signals that lose power over shorter distances, have poorer penetration characteristics, but that’s what we’ve got available.

For years I’ve been hearing people talk about WLANs becoming so fast and reliable it will soon replace wired connections to the desktop. I heard that twenty years ago, and it’s still not true today. I’m a “radio guy,” but trust me, if I can do it over a wire, I’m going with the wire.

Now we’re hearing the same thing about fixed wireless that will replace wired internet connections. I guess these guys weren’t around for WiMAX. WiMAX was a wireless technology based on the IEEE 802.16 series standards that emerged around the turn of the century and was going to deliver broadband internet service over fixed wireless. Then WiMAX was going to support mobile devices, too. In the end, it turned out to be a complete and total failure because all of the hardware manufacturers totally ignored it in favor of the 3GPP standards. However, there are a few rural areas that still depend on some type of fixed wireless internet access.

The other problem we have in developed countries is that people actually expect things to work. I’ve had the opportunity to travel around the world, and in many places, particularly poorer countries, nothing works so people develop amazing patience with non-working devices. That’s one of the reasons I’m so interested in seeing our first world technologies dropping in price so that people in these countries can afford them. These poor people have exercised “patience” for long enough. In the developed world, patience expired long ago.

The Wi-Fi equipment manufacturers have done a great job optimizing a solution for those problematic indoor environments – though you will have to spring for a professional RF site survey and sufficient access points and potentially specialized antennas to ensure the signal gets everywhere it needs to go.

The mobile operators have a much more challenging task as they have to cover the whole environment, indoors and out. And since customers pay for this service, they actually expect it’s going to work. The carriers’ solution to this problem is two fold: increase the range of available frequencies and reduce the coverage area of the cells. Put together, those two elements add up to a strategy the carriers call “Network Densification.”

The carriers have actually been doing something similar since the inception of the cellular industry, only now they have a cool name for it. The original plan for laying out cellular networks was to start with big cells (maybe a 10-mile radius), monitor where the calls were occurring, and divide those busy cells into smaller cells (maybe 3-mile radius). Network Densification is taking that to the next level and reducing the cell size to around 100 meters. The astute will recognize that 100-meter distance is also the planning range for Wi-Fi networks, though most of those now use a cell radius of 100 feet or less.

Reducing the required range from several miles to 100M, also has an impact on available frequencies. Those traditional macro cells operate on frequencies ranging from 600 MHz to around 2 GHz; WLANs run at 2.4G and 5 GHz. The mobile operators are now looking at using unlicensed frequencies in the 5GHz band. Carrier aggregation, now part of the cellular standards, will allow an operator to combine spectrum from several different bands into a single higher capacity radio channel.

There are a bunch of other bands under consideration as well including the 3.5 GHz CBRS band, Sprint’s 2.5 GHz channels, Verizon’s 28G/36 GHz holdings, and some are talking as high as 60G to 70 GHz. None of those make much sense for macro cell deployments, but they should work just fine (maybe not the 60-70 GHz stuff) in a small cell environment. The 3GPP cellular standards incorporate plans for integrating unlicensed bands called Licensed Assisted Access (LAA) and an industry group called the MulteFire Alliance is putting forth an alternative small cell standard that doesn’t require any licensed spectrum at all.

All of these plans are part of the fabric of 5G. However, as the mobile operators have proven time and again that they are totally inept at communicating what they are up to, there is no end to the misinformation surrounding 5G. The good news is that this whole idea of network densification and small cells are all taken into consideration in 5G, and the 5G radio links standards will be designed to operate over all of the bands we’ve mentioned as well as a bunch of others that are used in different parts of the world.

Will all of this finally deliver the type of reliable, seamless, ubiquitous cellular coverage that we all pine for? Probably not. However, it will give the carriers a much wider range of tools with which to address the problem, so things should definitely get better. Most promising among these are small cells that could be a far better and far cheaper means for improving indoor coverage than the traditional distributed antenna systems (DAS).

It also means that we will be looking at a major technology/architecture collision as mobile operators look to install their small cells in parallel with the customer’s Wi-Fi network and possibly operating on the same 5 GHz channels. Or maybe they’ll just use voice over Wi-Fi using the customer’s Wi-Fi network. Maybe the operators will look to buy that existing Wi-Fi infrastructure in lieu of investing in their own indoor coverage solution so they can guarantee the performance.

The bottom line is that there will soon be a lot more options on the table, and the vast majority of customers are completely ill-equipped to deal with them.


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