What is 5G?

In India, it all started with 2G, when in 1995 the first cellular licenses were issued. Then in 2010, India auctioned 3G spectrum in 2100 MHz band. Then recently, the operators started rolling out 4G in the 2G spectrum. The 4G networks are yet to stabilize, but we are now discussing 5G. This casual usage of technology jargons makes the layman confused. Many questions come to his mind. Such as, what does this transition mean for him? This note is an attempt to answer this question - as simply as possible.

Service Flexibility

"Service flexibility" depends upon the thickness of the pipe (generated by the technology) - used to connect the subscriber to the base station. The thicker the pipe, more the flexibility in offering services. The pipe enabled by 2G is the thinnest. Hence, 2G is limited to voices services only, and any data running on it is just an afterthought. 3G, on the other hand, thickens this pipe - enabling the operators to offer data services. In order to do so, 3G aggregates a large amount of spectrum (5 MHz vs 0.2 MHz of 2G). 4G increases the thickness of the pipe further. Hence, it aggregates 2 to 3 times spectrum compared to that of 3G. 5G widens the pipe substantially. To support that it needs a much broader spectrum chunks. Such larger blocks of spectrum can be found only in higher frequency bands. Hence, for 5G to work optimally, spectrum in 28 GHz or higher needs to be cleared and assigned. If we compare this with 2G bands, it is 30 to 40 times higher.

Service Reachability

In order to prevent coverage holes, it is important that density of base stations is sufficiently high for the radio signals to spread into all geographies including indoors. Unfortunately, as we move in the frequency bands the reachability of the radio waves exponentially decreases - requiring a large number of base stations (sites) in order to ensure ubiquitous coverage. This is bad news for 5G, it operates in the higher frequency bands to ensure wider data pipes. Hence, standalone 5G networks will need a disproportionately large number of sites to mirror the coverage of the existing technologies (2G,3G & 4G). This will be extremely difficult to achieve, and hence a standalone 5G cannot be worked practically. It will need the support of the existing technologies (running on lower spectrum bands) to ensure the reachability of basic services like voice. 5G networks will piggyback on 4G (like a wedding cake) and will cover only those areas where such speeds are justified and can be offered optimally.

Service Deliverability

"Service deliverability" of a technology depends upon its ability to leverage the frequency band to enhance the thickness of the data pipe. There is a physical limit to the maximum data that can flow in the pipe of a certain thickness. This is called the "Shannon Limit". This limit can be overcome by creating multiple pipes running parallel to each other in the same block of spectrum separated out in the spatial dimension. For that, we need multiple transmitting and receiving antennas both in the handhelds and the base stations. The size of these antennas increases at the lower frequencies, as it is directly proportional to the wavelength of the radio wave used for carrying information. Hence, at lower frequencies, this technique (called MIMO - Multiple Input Multiple Output) is difficult to implement (it increases the size of the handhelds and the base stations). On the other hand, 5G (operating is higher frequencies) can leverage this very easily. Using this technique 5G is able to make the data pipe much thicker compared to conventional technologies running at lower frequency bands. 4G also can leverage this technique (MIMO) provided it uses higher frequency bands. That is the reason why 5G cannot leverage its full potential if it is forced to operate in the lower spectrum bands.

Hence, 5G will not dismantle in the existing technologies (especially 4G). It will run on top of it, and in target areas where the need for data speeds is extremely high. 4G will continue to serve the consumer's basic voice and data needs, as it is deployed in the lower frequency bands which have much better coverage capabilities than those at the higher frequencies.

(Views expressed are of my own and do not reflect that of my employer)

PS: Find the list of other relevant articles in the embedded link.