Guest Post: A Reality Check on 6G Design Targets

May 10, 2023

Written by 6GWorld Contributor

By Heikki Almay, Co-Founder at Poutanet

Several times I have been asked to write about 6G. Now that conferences and research programs have moved from 5G to 6G and the hype starts building it is time to look at the key topics. In order to suppress my personal ranking I asked ChatGPT for a list to start with. Not so surprisingly AI and I mostly agree – but my favourite topic, UI flexibility, it missed. I will write about that topic later. Here is what ChatGPT brought up: 

              1. Extremely high data rates

              2. Ultra-low latency

              3. Massive connectivity

              4. Energy efficiency

              5. Security and privacy

Not too surprising. Here are the detailed statements with some thoughts about how things are today and what should be developed or fixed in 6G.

1. Extremely high data rates: 6G networks should be capable of providing data rates in the order of terabits per second (Tbps), which is 1000 times faster than 5G networks – or to be more precise, 1000 times faster than all the 5G marketing material that claims Gbps connectivity. Right now here in Helsinki my 5G download speed is 252 Mbps and I am happy. The 10 Mbps uplink speed could be improved. The really fast 5G speeds are found when mmWave spectrum (above 24 GHz) has been deployed. “Fast, but still expensive and hard to find” writes about mmWave 5G in 2023.

So today it is hard to find a business case for building Gbps-networks, and limited user equipment support does not improve the situation. In the future this may change and there are for sure use cases for 6G Tbps wireless communications beyond Speedtest – but if it is about medical imaging or collecting data from a Hadron Collider the need is quite local.

While we may argue about the urgency of Tbps speeds it means using new spectrum in the sub-THz range. This is a topic that the industry giants need to work on – not for meeting imminent customer demand, but for building IPR and for securing the frequencies for the 3GPP community.

2. Ultra-low latency: 6G networks should have latency in the order of microseconds (µs) or even lower. Reality check: Over my 5G (NSA) I get a ping back in 24ms. A few milliseconds of this time are spent by the radio interface (1 or 0.5ms transmission time interval). The rest is transport and processing delays. If I now magically had a 6G connection my ping would still be above 20ms. Obviously low latency benefits some use cases and is an enabler for others. Requirements for virtual or augmented reality applications are in the range of 10 – 20ms depending on the types of interactions.

3. Massive connectivity: 6G networks should be able to support a much larger number of devices than 5G, in the order of millions of devices per square kilometer. 1M devices per square km was already a 5G target – but so far the crowds of devices have not arrived. Smart homes and other IoT solutions have been built with Wi-Fi, Zigbee, Bluetooth and in some cases LoRaWAN. Why? The cost of these alternatives is lower both when building the product and when operating the devices.

Power consumption is another topic. The key issue is that to access a 3GPP network the IoT device needs to be smart enough for signaling with the network – and equipped with a SIM for authentication. To use the IPR related to these capabilities, a vendor has to pay extra and needs to perform a rigorous approval process on his device. Relaxing the requirements and rules for 6G IoT could help attract new users.

4. Energy efficiency: 6G networks should be designed to be much more energy-efficient than 5G, to support the massive number of connected devices and reduce the environmental impact of the networks. This is a standard requirement for every next generation. Proudly the industry shows that the energy efficiency per bit goes up. The total power consumption unfortunately does not, unless some legacy gear is decommissioned. Another common argument is that more connectivity is needed for digital transformation – and this eventually conserves energy.

If you look for real savings, it would be fairly straightforward to redesign the telephony and SMS services in such a way that they survive the changing of the user IP address (which in case of Voice over Wi-Fi happens anyway). This would allow us to sunset GTP tunneling or to make it optional. User traffic could be fed to the internet close to the base station where this is possible. This would be a relieve the burden on the backhaul transport infrastructure.

With such an architecture the need for IPsec between the base station and the core network (for securing the core) could be greatly reduced. Squeezing user packets into GTP tunnels that are then put into IPsec is an awfully inefficient tradition that has caused problems ever since 3G.

5. Security and privacy: 6G networks should provide strong privacy and security features to prevent cyberattacks and protect user data. Currently the most prominent type of attack on mobile users is SIM swapping. Telephone numbers are widely used for authentication purposes, and sending money to a phone number is common practice across the globe. This was hardly the intention when telephone numbering was developed over hundred years or so. What makes SIM swapping relatively straightforward is the ease of number portability. With social engineering or access to the telco core, moving a phone number to a new SIM is fast and easy. This is not how you expect your identity to be handled.

The challenge is not related to any particular generation of the mobile network, but 6G could fix the issue, for example by introducing new keys to the SIM or by creating safeguards for porting of telephone numbers. When it comes to privacy in current mobile networks we are all standing naked. Our devices’ apps and operating systems share data about the device location, surrounding radios including Wi-Fi and Bluetooth with – well, nobody seems to know with whom. Those few who have been suspicious enough to install GrapheneOS or some other non-Apple-Google OS on their device may have been disappointed when finding out that the SoC of their device sends data home, no questions asked.

The above examples illustrate that mobile network security and privacy is a massive topic – and way beyond defining just another radio interface. Yes, we should require strong encryption of the air interface and fixing of the obvious flaws in widely used services, but 3GPP can hardly change the fact that dominant operating systems and free-of-charge software have created an ecosystem where user data is a key currency.

One additional topic that has been little discussed is what can be learned from the introduction of 5G. There were a lot of expectations and a desire to beat the market with pre-standard solutions, and many deployment options – of which NSA has remained dominant in Europe. This brings up the question of whether it should be possible to introduce 6G with a 5G core – or perhaps even with a 4G core for those operators who do not see the business case for migrating their core and BSS.

I hope not, as this would further fragment the ecosystem. It would be great if 6G could be introduced as a true next generation.  

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