We’ve all seen the ads: “5G Is Coming!” We’ve seen the various cell companies hawking their latest 5G phones, even though it’s really only partially 5G. (More on that later.) It’s going to be the end all and be all of cell service, at least until 6G comes out. (Yes, they are already working on 6G even though 5G hasn’t been even been deployed yet.)
While 5G is the latest and greatest in the way of cell technology, it is unlikely that many of us will be enjoying everything 5G has to offer, including 1 Gigabit connectivity to the ‘Net. The reason this will be an issue comes down to one simple thing: bandwidth.
Initial 5G deployments will use the existing cellular radio bands in 600MHz, 700MHz, 800MHz, 1.9GHz, 2.5GHz and the new 3.7GHz band. The present 3G and 4G/LTE cell services use some of these bands. (It is my understanding the cell carriers will start shutting down 3G services later this year as 3G phones are aging out and they are being replaced by 4G/LTE and 5G phones.)
One of the aspects of 5G is the use of new millimeter-wave radio bands that offer more bandwidth that existing cellular radio bands cannot provide. With frequencies allocations in the 28GHz, 36GHz, 40GHz, and 72GHz bands and making use of phased array antennas to steer signals towards 5G enabled phones. While having some of the same characteristics as the MIMO style antennas used with some 4G systems where the antennas can be used to do some limited signal steering, phased array antennas used for 5G can steer signals in both azimuth and elevation, creating separate signal beams for each phone or groups of phones in range of a 5G cell station. This is one of the enabling technologies of 5G that will help it provide the services 4G cannot. However, this is only the plus side of the use of millimeter-wave frequencies.
The down side?
One of the biggest problems with the millimeter-wave frequencies being used for 5G is the high signal loss over distance, it being higher than that seen in 3G and 4G. Because of that higher path loss, the number of 5G cell sites required to provide coverage similar to present 4G systems is greater, somewhere on the order of 5 to 20 times the number. There are presently somewhere around 350,000 3G/4G/LTE cell sites in the US. To provide the same coverage using millimeter-wave frequencies would require 1,750,000 to 7,000,000 cell sites, something that isn’t likely happen any time soon. As such it’s a pretty good bet that 5G millimeter-wave cell sites will only be deployed in urban and more heavily settled suburban areas. Deployment in more thinly settled suburban and rural areas is probably a money loser for carriers so it is unlikely we’ll see such deployment in those areas any time soon. Those of us living in those areas will have to settle for slower data speeds because we’ll be relegated to the existing cell phone bands. Then again how many of us really need 1 Gigabit/second service, at least at this point? Many of us don’t even have that kind of service from our ISPs and we don’t seem to be suffering too much. (For full disclosure, I do have that type of service available from my ISP, but I don’t want to pay that kind of money when 100Mbits/second seems to work just fine. Better that we see an improvement in latency (time delay) which can have a bigger effect on effective data speeds than the raw data speed itself.
Another issue that has raised its ugly head is the possible health effects of the millimeter-wave radio signals on biological systems. There have been many claims regarding the biological effects of exposure to millimeter-wave radiation running the gamut of headaches to cancer to having kids with three heads. (OK, so maybe I am exaggerating about three-headed kids.) However, there have been some concerns with the effects of millimeter-wave radiation on human health and some doctors and scientists have been calling for a moratorium on deployment of millimeter-wave 5G systems until further studies have been completed. The problem could lie with the RF radiation from the cell phones, not the cell sites if there is indeed a problem.
Not much in the way of 5G millimeter-wave cell sites have been deployed as there have been some technical issues with the ability of the phased array antenna systems to track faster moving mobile customers and maintaining connection with the cell phones. There have been a small number of cities that have been used as testing sites by the cell carriers, but widespread deployment hasn’t really started as best I have been able to determine.
5G is coming…but it’s coming really slow.
