5GS, EPS Fallback for IMS voice service

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  • In the initial phase of 5G deployment due to some issues such as 5G NR discontinuous coverage, 5G devices that do not support VoNR (voice over NR), and perhaps 5G BS (Base Station) does not support VoNR, EPS Fallback is the best option to redirect the 5G devices from 5GS to EPC to make a VoLTE call.

  • EPS fallback to EUTRA can be done using blind RwR (Release with Redirect),measurement-based RwR and measurement-based handover.

  • 5G NR devices supporting S1 mode (which is vital for EPS fallback) should operate in the mode of Single Registration or Dual Registration.

  • To reduce the VoLTE call setup time, N26 should be supported between EPC and 5GC especially for the devices operating in Single Registration Mode.

  • Here I try to depict the 5GS and EPC architecture to support EPS Fallback, which is essential for IMS audio service.

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LinkedIn: Rahim Navaei on LinkedIn: #5g #5gnr #4g | 20 comments

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