Draft: 5G NTN specific changes from ESA 5G-GOA project

5G-NTN specific changes from ESA project 5G-GOA:

• PHY Layer
  • Extend OAI rf-simulator to support simulation of long delay
  • Consider timing relation for UL scheduling at gNB
  • Disabling HARQ at gNB and UE
• MAC Layer
  • Adapting Uplink timing advance and RA procedure
• RLC Layer
  • Disabling HARQ-ARQ interaction
  • Increased ARQ buffer size to cope with large GEO delay
  • Increased maximum Sequence Number value
• PDCP Layer
  • Increased discard timer for SDU buffer
  • Increased reordering timer for PDU buffer
  • Increased size of PDU buffer
• RRC Layer
  • Increased selected timers (T300, T301, T311)

Project homepage: https://artes.esa.int/projects/5ggoa

Additional command line options:

Option	Description	Parameter
-P	rf-simulator propagation delay	in samples
--no-harq	Disable HARQ
--gnb_k2	gNB k2-offset	in slots
--ue_k2	NR_UE k2-offset	in slots
--ul_sched_f	Extend gNB UL scheduling window	in frames (must be power of two)
--ue_slot_Rx_Tx	Extend NR-UE gNB DURATION_RX_TO_TX	in slots
--ntn-trs	t_Reassembly timer enum	0 to 30
--ntn-trs-offset	Offset to be added to t_Reassembly timer	in ms
--ntn-rtd	Round trip delay	in ms but has to be matched with the one given by -P
--ntn-trd	t_Reordering timer enum	0 to 35
--ntn-trd-offset	Offset to be added to t_Reordering timer	in ms

Execution example for this scenario:

• FDD
• 30 kHz SCS
• 10 MHz BW
• 260 ms one-way propagation delay
• 520 ms RTT
• k2_offset = 1040 slots

At gNB:

RFSIMULATOR=server sudo -E ./ran_build/build/nr-softmodem -O ../targets/PROJECTS/GENERIC-LTE-EPC/CONF/gnb.band66.tm1.24PRB.usrpx300.conf --noS1 --nokrnmod --phy-test --rfsim --no-harq -P 3993600 --gnb_k2 1040 --ul_sched_f 64 --ntn-trs 10 --ntn-trs-offset 200 --ntn-rtd 230 --ntn-trd 15 --ntn-trd-offset 200

At UE:

RFSIMULATOR=127.0.0.1 sudo -E ./ran_build/build/nr-uesoftmodem --noS1 --nokrnmod --phy-test --rfsim --no-harq -P 3993600 -A 7987200 --ue_slot_Rx_Tx 1040 --ue_k2 1040 --ntn-trs 10 --ntn-trs-offset 200 --ntn-rtd 230 --ntn-trd 15 --ntn-trd-offset 200