The Podcast: 5G NR, backhaul and metaverse

Scott manages to limp in for an episode with just Iain and, of course, Pierre this week. They start by devoting a whole segment to 5G New Radio, questioning whether it’s all it’s cracked up to be. They move on to the often overlooked matter of backhaul and what it means for one operator to be dependent on another for that sort of thing, before concluding with a look at plans to develop a metaverse for kids.


  1. Avatar Martin 12/04/2022 @ 10:30 am

    Hi, loving the podcast and the benign, informal chatter as always!

    I wanted to add a few comments to the “5G NR BS” topic.

    As you pointed out the most obvious change with 5G NR was of course that new spectrum was introduced – using much higher frequencies and also more of it as each carrier can be up to 400 MHz wide, whereas 4G could only be a maximum of 20MHz. This has needed new physical radios units of course, which is why operators have had to add 5G antennas to their cell towers. It has also led to a lot of innovation in the radio space. For example because the frequencies are higher, the antennas are much smaller and you can actually fit dozens or even hundreds of small antennas in a single radio unit, known as an “active antenna” or “phased array” and this Massive-MIMO setup is the technology that provides beamforming; where the cell site will provide a concentrated beam of signal that physically follows your device around the cell area. This can extend coverage area, reduce noise and allow for frequency reuse. We are also starting to see technology such as Interleaved Passive Active Antenna (IPAA) where you have a traditional passive antenna (which could be 4G or 5G, or both using dynamic spectrum sharing) and an active antenna or phased array sitting behind it and transmitting “through” the passive antenna – all combined in a single unit.

    In terms of the underlying standards it gets more complicated and I’m not an expert in the low level working but will try and provide some insight… 5G New Radio was genuinely developed from scratch by the 3GPP working groups, starting with looking at the future requirements including fibre-like-broadband, low latency mission critical comms and a lot of IoT devices needing to send small data rates and have very long battery life (5G NR is designed to support a million devices per square km – you can’t do that with 4G!) As you pointed out it did end up settling on the same underlying modulation scheme as 4G (Cyclic Prefix Orthogonal Frequency Division Multiplexing or CP-OFDM), although it is heavily optimised by using new methods and channel coding techniques. It also offers significant efficiency gains over 4G, with consumption of both power and spectrum a key focus, with a number of low power functions, new inactive states introduced and signalling being redesigned to be much leaner. Efficiency improvements also provide capacity gains, for example by using very sophisticated algorithms to enable frequency reuse even in dense environments, so you don’t see such a drop off in performance when a site gets busy.

    One of the game changers is that it moves from 4G which is a “best efforts” consumer network to an enterprise level network where you can offer guaranteed SLAs or QoS and even use it for mission critical ultra-reliable low-latency communication (URLLC). 5G NR was developed to offer very low latency by adapting time slot operations through a complex engineering concept called ‘Flexible Numerology’ (not used in 4G) and it doesn’t treat all devices as equal, so whereas in 4G a device had to wait for a gap in network traffic to transmit (which could be a long time in a congested area), a self-driving car that’s about to crash can effectively say “hey I need to talk!” and the gNB tells all the other devices to shut up.

    It’s an interesting question on how new and radical 5G NR really is and whether it’s a step change or a series of enhancements over 4G. The challenge with radio of course, over the core network or IT systems, is that you can’t easily iterate – you can’t release a series of software updates over weeks and months as it’s physical hardware that has to be added or swapped out and therefore you do need to bundle up improvements and build a very strong business case to add / swap radios across your tens of thousands of cell sites. It also needed a single ‘moment’ to upgrade all the backhaul and I understand the majority of sites with 5G NR have been upgraded to 10GB fibre as part of the deployment.

    I think the other reason it doesn’t feel like 5G is a step change over 4G is the way it’s being rolled out. In the UK right now we have Option 3 Non-Standalone (NSA) mode which is effectively 4G with an additional NR carrier added for some extra bandwidth, so you don’t get the benefit of the 5G Core, service based architecture, early breakout of the userplane etc and currently the new 5G bands are all sub 6 GHz and not in 5G NR Frequency Range 2 (FR2) which is in the 28-47 GHz range and offer the headline speeds and capabilities (these will be in future UK license spectrum auctions). This architecture is only useful for enhanced mobile broadband and not any of the future application all the hype is around, from self-driving cars to the robotic surgery Scott is so taken by!

    Cheers and keep up the great work.

    • Scott Bicheno Scott Bicheno 13/04/2022 @ 9:29 am

      That’s brilliant feedback, Martin – much appreciated. So, if I have understood correctly, we do have a point when making like-for-like comparisons between 4G and 5G NR when it comes to throughput, but NR brings a lot else to the table on top of that, which is only fully realised on a fully 5G SA network.

      I have a feeling this topic still has some legs in it, especially while the overall case for 5G remains less than conclusive.

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