The sub-6 GHz frequency bands and the millimeter wave or mmWave spectrum are two frequency specifications defined and allocated for 5G technology. Fundamentally, the entire fifth-generation standard for cellular network technology defined by the 3rd Generation Partnership Project or 3GPP international consortium is based on two different specifications.
Not all 5G networks and 5G devices are the same because of the inherent differences between sub-6 5G and mmWave 5G. The Sub-6 GHz specification uses different technologies and works on distinctive principles than mmWave specification. Some devices are only compatible with sub-6 networks while others only run on mmWave networks.
Understanding the Difference Between Sub-6 GHz 5G and mmWave 5G: What is the Difference Between the Two? Which One is Better?
3GPP introduced the 5G New Radio or 5G NR air interface to defined and standardize the development and deployment of 5G networks and 5G capabilities. The NR standard is subdivided further into two frequency band specifications: Frequency Range 1 or sub-6 GHz and Frequency Range 2 or mmWave.
The primary difference between sub-6 GHz 5G and mmWave 5G is considerably straightforward: the former represents 5G networks that run at frequencies below 6 GHz while the latter represents frequency bands in the upper limits of radio waves or within the range of microwaves.
More specifically, the commonly used fifth-generation frequencies under the Sub-6 specification are within the 3.3 GHz and 4.2 GHz range. Note that 4G Long-Term Evolution and 4G LTE Advanced networks also runs on frequencies within the same sub-6 GHz range and further below the sub-3 GHz band.
On the other hand, the mmWave specification is unique to 5G technology. The network performance that sets apart the 5G from 4G technologies comes from using electromagnetic radiation frequencies between 24 to 30 GHz and 300 GHz.
Below are the specific differences between the two in terms of infrastructure requirements, and network performance:
1. Infrastructure Requirements
Sub-6 GHz 5G networks generally use the existing infrastructures of 4G systems, albeit with some added modifications. On the other hand, mmWave 5G networks require the newer infrastructures characterized by the deployment of smaller cells to provide network services. Deploying mmWave 5G is considerably more expensive than deploying sub-6 GHz 5G because it requires hundreds to thousands of smaller cells to cover a specific area and integration of complementary technologies such as MU-MIMO, massive MIMO, and beamforming.
2. Coverage and Range
Another notable difference between sub-6 GHz 5G and mmWave 5G is the range in which electromagnetic signals can travel. Frequencies within the sub-6 GHz specification are lower and their wavelengths are longer than the mmWave specification. Because mmWave frequencies are higher and their wavelengths are shorter, they cannot travel at long distances and get through physical obstructions.
3. Network Performance
Frequencies within the millimeter wave specification have larger bandwidth capacities and can transmit data faster than frequencies below the 30 GHz and 3000 GHz range. The same is true for all other radio and microwave frequencies. Hence, mmWave 5G inherently and theoretically has better bandwidth, network latency, and data transmission speed than sub-6 GHz 5G.
Sub-6 GHz 5G vs. mmWave 5G in a Nutshell: An Overview of Their Differences and Considerations for Network Operators and Consumers
Note that higher frequencies and shorter wavelengths translate to better data transmission speeds. To explain further, high frequency is associated with a faster movement of signal-bearing electromagnetic waves. Hence, mmWave 5G networks are generally better than sub-6 GHz 5G networks in terms of data transmission speed.
However, although cellular networks based on millimeter wave specifications are ultra-fast, they are ultra-short range. The general rule is that the higher the frequency and the shorter the wavelength, the shorter the distance the electromagnetic radiation can travel and the higher the susceptibility to physical obstructions such as concrete walls.
Unlike sub-6 GHz networks, signals from mmWave cells cannot go through wooden and concrete walls and some glasses. Even trees can become an obstruction. Connecting to these cells also depends on a line of sight. Hence, network performance depends not only on the proximity of the users but also on their specific positions relative to a mmWave cell.
Sub-6 GHz 5G networks are easier to deploy because they can use existing 4G infrastructures. The nature of sub-6 frequencies also means that there is no need for network carriers to build more cell towers or cell sites within a particular area to maximize coverage. Meanwhile, mmWave 5G networks are ideal in dense urban areas and specific target spots such as stadiums.
Deploying a robust millimeter wave network would require operators to place hundreds to thousands of smaller cells in every corner of streets and buildings. Doing so would maximize the full potential of fifth-generation network connectivity since the mmWave specification delivers faster data transmission speed, larger bandwidth capacity, and better network latency.
End-users of wireless communication would need to understand the specifications of the devices that they are planning to purchase. Remember that not all 5G devices are the same. Some devices only support the sub-6 specification while others only support the mmWave specification. Each specification uses different technologies and works on distinctive principles
FURTHER READINGS AND REFERENCES
- Konsyse. 2021. “Advantages and Disadvantages of Sub-6 GHz 5G.” Konsyse. Availanle online
- Konsyse. 2021. “Electromagnetic Radiation: Characteristics and Properties.” Konsyse. Available online
- Kumar, A. and Gupta, M. 2018. “A Review on Activities of Fifth Generation Mobile Communication System.” Alexandria Engineering Journal. 57(2): 1125-1135. DOI: 1016/j.aej.2017.01.043
- Parkvall, S., Dahlman, E., Furuskar, A., and Frenne, M. 2017. NR: “The New 5G Radio Access Technology.” IEEE Communications Standards Magazine. 1(4): 24-30. DOI: 1109/mcomstd.2017.1700042
- Zada, M., Shah, I. A., & Yoo, H. (2021). “Integration of Sub-6-GHz and mm-Wave Bands With a Large Frequency Ratio for Future 5G MIMO Applications.” IEEE Access. 9: 11241-11251. DOI: 1109/access.2021.3051066