The key performance indicators (KPIs) have to a large extent stayed the same in different network generations starting from 1G to 5G and now 6G , with progression of each generation the minimum requirements have sharpen. The energy efficiency KPIs is an exception , which was first introduced in 5G, but without specifying concrete targets.
It is believed that 6G will mainly contain the same KPIs as previous generations but with greatly higher ambitions. However, while the KPIs were mostly independent in 5G (but less stringent at high mobility and over large coverage areas), a cross-relationship is desirable in 6G through a definitions of groups. All the indicators in a group should be fulled at the same time, but different groups can have diverse requirements.
The reason is that we will move from a situation where broadband connectivity is delivered in a single way to a situation where the requirements of different broadband applications become so specialised that the union of them cannot be simultaneously achieved. Hence, 6G will need to be real-time configurable to cover to these different groups.
The following are the desirable KPIs for 6G Wireless Access.
- Extreme Data Rates: Peak data rates up to 1 Tbps are expected for both indoor and outdoor connections. The user-experienced data rate, which is guaranteed to 95% of the user locations, is desired to reach 1 Gbps.
- Enhanced Spectral efficiency and Coverage: The peak spectral efficiency can be increased using improved MIMO technology and modulation schemes, likely up to 60 b/s/Hz. However, the largest expected improvements are in terms of the uniformity of the spectral efficiency over the coverage area. The user-experienced spectral efficiency is desired to reach 3 b/s/Hz. Additionally, new PHY layer algorithms are needed to allow for broadband connectivity in high mobility scenarios and more broadly the scenarios for which legacy wireless networks generations do not fully meet the needs.
- Extra Wide Bandwidths: To support extremely high peak rates, the maximum supported bandwidth must greatly increase. Bandwidths up to 10 GHz can be supported in mmWave bands, while up to 100 GHz can be reached in THz and visible light bands.
- Enhanced Energy Efficiency: Focusing on sustainable development, 6G technologies are expected to pay attention in achieving better energy efficiency, both in terms of the absolute power consumption per device and the transmission efficiency. In the latter case, the efficiency should reach up to 1 terabit per Joule. Hence, developing energy-efficient communication strategies is a core component of 6G.
- Ultra-Low Latency: The use of bandwidths that are wider than 10 GHz will allow for latency down to 0.1 ms. The latency variations (jitter) should reach down to 1 micro sec, to provide an extreme level of determinism.
- Extremely High Reliability: Some new use cases require extremely high reliability up to 1-10^-9
to enable mission critical applications. It is unlikely that all of these requirements will be simultaneously supported, but different use cases will have different sets of KPIs, where of only some reach the maximum requirements mentioned above.
Comparison of 5G and 6G KPIs
A comparison of the 5G KPIs and 6G KPIs is shown in below, where also the area traffic capacity and connection density are considered. It is likely that 6G will to a large extent carry information related also to non-traditional applications of wireless communications, such as distributed caching, computing, and AI decisions. Thus, it need to be studies that whether there is a need to introduce new KPIs for such applications, or if the traditional KPIs are enough .
- White Paper on Broadband Connectivity in 6G