3.6.1. O-RAN IP Examples for Transmission and Reception Window Thresholds
Downlink U-Plane
Reception window boundary forms with air interface based on t2a_min_up and t2a_max_up.
Reception window upper boundary = air interface – t2a_min_up.
Reception window lower boundary = air interface – t2a_max_up.
O-RAN receive time = –t2a.
eg: 0s – t2a, 2.56s – t2a, 5.12s – t2a …
If lower bound and upper bound values are negative, you must add + 2.56 s (wrapping period 2.56 s, O-RAN spec v9.0 WG4, 7.5.2.4.) The negative value can only occur at reception side.
Calculation for 15 kHz SCS:
- FrameID = 20
- SubframeID = 5
- SymbolID = 2
Air interface = frameID*10 ms + subframeID*1 ms + symbolID (refer to Table 22)
= 20 * 10 ms + 5 * 1 ms + symbolID 2
= 20 * 10 ms + 5 * 1 ms + 143229 (from Table 22 symbolID 2: H’22F7D)
= 200 ms + 5 ms + 0.143229 ms
= 205.143229 ms
= 0.205143229 s
0 | 00000 |
1 | 118C3 |
2 | 22F7D |
3 | 34637 |
4 | 45CF1 |
5 | 573AC |
6 | 68A66 |
7 | 7A120 |
8 | 8B9E3 |
9 | 9D09D |
A | AE757 |
B | BFE11 |
C | D14CC |
D | E2B86 |
Calculation for 30 kHz SCS:
- FrameID = 20
- SubframeID = 5
- SlotID = 1
- SymbolID = 2
Air interface = frameID*10 ms + subframeID*1 ms + slotID * 0.5ms symbolID (refer to Table 23)
= 20 * 10 ms + 5 * 1 ms + 1 * 0.5ms + symbolID 2
= 20 * 10 ms + 5 * 1 ms + 1 * 0.5ms + 71864 (from Table 23 symbolID 2: H’118B8)
= 200 ms + 5 ms + 0.5ms + 0.071864 ms
= 205.571864 ms
= 0.20571864 s
0 | 00000 |
1 | 08D5A |
2 | 118B8 |
3 | 1A416 |
4 | 22F74 |
5 | 2BAD2 |
6 | 34630 |
7 | 3D18E |
8 | 45CEC |
9 | 4E84A |
A | 573A8 |
B | 5FF06 |
C | 68A64 |
D | 715C2 |
Downlink Packet arrives on time
FrameID = 20; SubframeID = 5; SymbolID = 2. An offset of 0.205143229 s relative to the start of frame.
FrameID*10ms + Subframe*1ms + SymbolID (1ms/14 + CP)
Referring to Figure 21:
- Air interface = 0.205143229 s
- t2a_min_up = 98 us, t2a_max_up = 103 us
- Upper boundary = 0.205143229 s – 98 us = 0.205045229 s
- Lower boundary = 0.205143229 s – 103 us = 0.205040229 s
- O-RAN receive time = 0.205043229 s
For a 0 s boundary, the O-RAN receive time 0.205043229 s falls between lower boundary 0.205040229 s and upper boundary 0.205045229 s. The IP receives this packet receive and counts it as on time.
For a 2.56 s boundary, the O-RAN receive time of 2.765043229 s (0.205043229 s + 2.56 s) falls between lower boundary 2.765040229 s (0.205040229 s + 2.56 s) and upper boundary 2.765045229 s (0.205045229 s + 2.56 s). The IP receives this packet receive and counts it as on time.
Downlink Packet arrives early
FrameID = 20; SubframeID = 5; SymbolID = 2 An offset of .2051430229 s relative to the start of frame.
Referring to Figure 23:
- Air interface = 0.205143229 s
- t2a_min_up = 98 us, t2a_max_up = 103 us
- Upper boundary = 0.205143229 s – 98 us = 0.205045229 s
- Lower boundary = 0.205143229 s – 103 us = 0.205040229 s
- O-RAN receive time = 0.2049 s
For a 0 s boundary, the O-RAN receive time of 0.2049 s fall before lower boundary 0.205040229 s. The IP drops this packet and counts it as early.
For a 2.56 s boundary, the O-RAN receive time of 2.7649 s (0.2049 s + 2.56 s) fall before lower boundary 2.765040229 s (0.205040229 s + 2.56 s). The IP drops this packet and counts it as early.
Downlink Packet arrives late
Referring to Figure 25:
- Air interface = 0.205143229 s
- t2a_min_up = 98 us, t2a_max_up = 103 us
- Upper boundary = 0.205143229 s – 98 us = 0.205045229 s
- Lower boundary = 0.205143229 s – 103 us = 0.205040229 s
- O-RAN receive time = 0.205093229 s
For a 0 s boundary, the O-RAN receive time of 0.205093229 s fall after upper boundary 0.205045229 s. The IP drops this packet and counts it as late.
For a 2.56 s boundary, the O-RAN receive time of 2.765093229 s (0.205093229 s + 2.56 s) falls after upper boundary 2.765045229 s (0.205045229 s + 2.56 s). The IP drops this packet and counts it as late.
Uplink U-Plane
Transmission window boundary forms with air interface, ta3_min_up and ta3_max_up.
Transmission window upper boundary = air interface + ta3_max_up.
Transmission window lower boundary = air interface + ta3_min_up.
O-RAN transmit time = ta3
eg: 0 s + ta3, 2.56 s + ta3, 5.12 s + ta3 …
If lower bound and upper bound values are more than 2.56 s, you need to offset it by - 2.56 s (wrapping period 2.56 s, O-RAN spec v9.0 WG4, 7.5.2.4 .)
Calculation for 15 kHz SCS:
- FrameID = 20
- SubframeID = 5
- SymbolID = 2
Where air interface = frameID*10ms + subframeID*1 ms + symbolID (refer to Table 22)
eg: air interface = frameID*10 ms + subframeID*1 ms + symbolID 2
= 20 * 10 ms + 5 * 1 ms + SymbolID 2
= 20 * 10 ms + 5 * 1 ms + 143229 (from Table 22 SymbolID 2: H’22F7D)
= 200 ms + 5 ms + 0.143229 ms
= 205.143229 ms
= 0.205143229 s
Uplink Packet arrives on time
Referring to Figure 27:
- Air interface = 0.205143229 s
- ta3_min_up = 98 us, ta3_max_up = 103 us
- Upper boundary = 0.205143229 s + 103 us = 0.205246229 s
- Lower boundary = 0.205143229 s + 98 us = 0.205241227 s
- O-RAN transmit time = 0.205243229 s
For a 0 s boundary, the O-RAN transmit time of 0.205243229 s falls between lower boundary 0.205241227 s and upper boundary 0.205246229 s. The IP receives this packet and counts it as on time.
For a 2.56 s boundary, the O-RAN transmit time of 2.765243229 s (0.205243229 s + 2.56 s) falls between lower boundary 2.765241227 s (0.205241227 s + 2.56 s) and upper boundary 2.765246229 s (0.205246229 s + 2.56 s). The IP receives this packet and count it as in time.
Uplink Packet arrives early
The ta3 change becomes smaller.
FrameID = 20; SubframeID = 5; SymbolID = 2
An offset of 0.205143229 s relative to the start of frame.
Symbol received earlier at air interface.
Referring to Figure 29:
- Air interface = 0.205143229 s
- ta3_min_up = 98us, ta3_max_up = 103 us
- Upper boundary = 0.205143229 s + 103 us = 0.205246229 s
- Lower boundary = 0.205143229 s + 98 us = 0.205241227 s
- O-RAN transmit time = 0.2052 s
For a 0 s boundary, the O-RAN transmit time of 0.2052 s falls before lower boundary 0.205241227 s. The IP drops this packet and counts it as early.
For a 2.56 s boundary, the O-RAN transmit time of 2.7652 s (0.2052 s + 2.56 s) falls before lower boundary 2.765241227 s (0.205241227 s + 2.56 s). The IP drops this packet and counts it as early.
Uplink Packet arrives late
FrameID = 20; SubframeID = 5; SymbolID = 2
An offset of 0.205143229 s relative to the start of frame.
Referring to Figure 31:
- Air interface = 0.205143229 s
- ta3_min_up = 98us, ta3_max_up = 103 us
- Upper boundary = 0.205143229 s + 103 us = 0.205246229 s
- Lower boundary = 0.205143229 s + 98 us = 0.205241227 s
- O-RAN transmit time = 0.2053 s
For a 0s boundary, the O-RAN transmit time of 0.2053 s falls after upper boundary 0.205246229 s. The IP drops this packet and counts it as late.
For a 2.56s boundary, the O-RAN transmit time of 2.7653 s (0.2053 s + 2.56 s) falls after upper boundary 2.765246229 s (0.205246229 s + 2.56 s). The IP drops this packet and counts it as late.