Thursday, 27 February 2020

5G and Industry 4.0


Telefónica published an infographic on 'Benefits of 5G in Industry 4.0' last week. You can download it on their website here. This reminded me that we have now completed the third video in our series of IoT.

  1. The beginners guide to M2M, MTC & IoT is discussed here and video is available here.
  2. Industrial IoT (IIoT) vs IoT is discussed here.
  3. This blog post with with embedded video / slide looks at Industrie 4.0 (a.k.a. I4.0 or I4)



Slides and Video is embedded below, let us know what you think.






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Friday, 21 February 2020

EPS Fallback in 5G Standalone Deployments

It can be expected that later this year some mobile network operators will launch their initial 5G standalone (5G SA) deployments.

Nevertheless there will remain areas with temporary or permanently weak 5G NR coverage. One possible reason might be that even when 5G and LTE antennas are co-located, which means: mounted at the same remote radio head, the footprint of the 5G NR cell is significantly smaller when it uses a higher frequency band than LTE - see figure 1.

Figure 1: Smaller footprint of co-located 5G NR cell with higher frequency
Especially UEs making Voice over New Radio (VoNR) calls from the 5G cell edge have a high risk of experiencing bad call quality, in worst case a call drop. To prevent this the UE is forced  during the voice call setup towards 5G core network (5GC) to switch to a LTE/EPS connection where the radio conditions are better for the voice service.

The same procedure for which the term "EPS Fallback" was coined by 3GPP also applies when the UE is served by a 5G cell that is not configured/not optimized for VoNR calls or when the UE does not have all needed VoNR capabilities.

Figure 2: Two options for EPS fallback

When looking at the RAN there are two options for executing the EPS Fallback as shown in figure 2.

In option A the 5G radio connection is released after the initial call attempt is successfully finished and with the 5G RRC Release the UE is ordered to reselect to a 4G cell where a new radio connection is started for the VoLTE call. In this case the UE context is transferred from the AMF to the MME over the N26 interface. 3GPP seems to use also the term "RAT fallback" for this option.

Option B is to perform a 5G-4G inter-RAT handover. Here the session management and user plane tunnels in the core network are handed over from SMF/UPF to MME/S-GW in addition. This is realized with the GTPv2 Forward Relocation procedure on N26 interface.

All in all the EPS fallback is expected to cause an additional call setup delay of approximately 2 seconds.

For the inter-RAT handover case it is easy to detect from signaling information that an EPS fallback was triggered. In the source-eNodeB-to-target-eNodeB-transparent-container sent by the gNB to the eNB a boolean "IMS voice EPS fallback from 5G" indicator will be found that is set to "true". This container is named according to the receiving entity and will be carried by the NGAP Handover Preparation, GTPv2 Forward Relocation Request and the S1AP Handover Request messages.

If a redirection for Voice EPS Fallback is possible or not is indicated in the NGAP Initial Context Setup Request, Handover Request (during 5G intra-system handover) and Path Switch Request Acknowledge (after Xn handover) messages, all sent by the AMF to the gNB.

Further the NGAP protocol provides the cause value "IMS voice EPS fallback or RAT fallback triggered" in the PDU Session Resource Modify Response message indicating that a requested VoNR session cannot be established.  





Wednesday, 12 February 2020

AI your Slice to 5G Perfection


Back in November, The Enhanced Mobile Broadband Group in CW (Cambridge Wireless) held an event on 'Is automation essential in 5G?'. There were some thought provoking presentations and discussions but the one that stood out for me was by Dan Warren from Samsung


The slides are embedded below but I want to highlight these points:
  • Some Network Functions will be per slice whereas others will be multi-slice, the split may not be the same for every slice
  • Two slices that have the same 'per slice vs multi-slice' functional split may be different network hardware topologies
  • Enterprise customers will likely want a 'service' contract that has to be manifested as multiple slices of different types. 
  • Physical infrastructure is common to all slices
The last point is very important as people forget that there is a physical infrastructure that will generally be common across all slices.

Again, when you apply Artificial Intelligence (AI) to optimize the network functions, does it do it individually first and then end-to-end and if this is applied across all slices, each of which may have a different functionality, requirement, etc. How would it work in practice?




As Dan says in his tweet, "It is hard to implement AI to optimise a point solution without potentially degrading the things around it.  Constantly being pushed to a bigger picture view => more data => more complexity"

Let me know what you think.

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