O-RAN Intel® FPGA IP User Guide

ID 683238
Date 8/15/2023
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3.6.1. O-RAN IP Examples for Transmission and Reception Window Thresholds

This topic shows on-time, early, and late U-plane examples.

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

Where air interface = frameID*10 ms + subframeID*1 ms + symbolID (refer to Table 20)

eg: air interface = frameID*10 ms + subframeID*1 ms + symbolID

= 20 * 10 ms + 5 * 1 ms + symbolID 2

= 20 * 10 ms + 5 * 1 ms + 143229 (from Table 20 symbolID 2: H’22F7D)

= 200 ms + 5 ms + 0.143229 ms

= 205.143229 ms

= 0.205143229 s

Table 20.  15 kHz SymbolId LUT
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

Downlink Packet arrives on time

Figure 20. Downlink U-Plane On Time Example 1 FrameID = 0; SubframeID = 0; SymbolID = 0
Figure 21. Downlink U-Plane On Time Example 2

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

Figure 22. Downlink U-Plane Early Example 1 FrameID = 0; SubframeID = 0; SymbolID = 0
Figure 23. Downlink U-Plane Early Example 2

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

Figure 24. Downlink U-Plane Late Example 1 FrameID = 0; SubframeID = 0; SymbolID = 0
Figure 25. Downlink U-Plane Late Example 2 FrameID = 20; SubframeID = 5; SymbolID = 2 An offset of 0.205143229 s relative to the start of frame.

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 20)

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 20 SymbolID 2: H’22F7D)

= 200 ms + 5 ms + 0.143229 ms

= 205.143229 ms

= 0.205143229 s

Uplink Packet arrives on time

Figure 26. Uplink U-Plane On Time Example 1 FrameID = 0; SubframeID = 0; SymbolID = 0
Figure 27. Uplink U-Plane On Time Example 2 FrameID = 20; SubframeID = 5; SymbolID = 2

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

Figure 28. Uplink U-Plane Early Example 1 FrameID = 0; SubframeID = 0; SymbolID = 0

The ta3 change becomes smaller.

Figure 29. Uplink U-Plane Early Example 2

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

Figure 30. Uplink U-Plane Late Example 1 FrameID = 0; SubframeID = 0; SymbolID = 0
Figure 31. Uplink U-Plane Late Example 2

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.