Consideration on PRACH Detection Design
Written by
Keith
on
on
Physical random access channel and random access procedure
PRACH preamble format details for long/short sequence length
Include discussion and evaluation based on email discussion [89-16], whether/how to support restricted set, etc. Limit to 1 contribution per 1 company/organization/university
Agreements:
- Confirm the working assumption on supporting format 3
- For formats with L=839
- Unrestricted sets are supported
- For restricted sets
- 1.25 kHz: Restricted set A supported, Restricted set B is FFS
- 5 kHz: Restricted set is supported with FFS if Restricted set A, B or both are supported
- For L=127/139 with option 1, formats with 1,2,4,6, and 12 OFDM symbols are supported
- Number of symbols can be adjusted if problems are identified
Way forward for PRACH preamble format for long/short sequences
Agreements:
- For 15 kHz subcarrier spacing,
- Agree on following preamble formats A2, A3, B4
- Working assumption on following preamble formats A0, A1, B0, B1, B2, B3, C0, C1
| Preamble format | # of Sequence | TCP | TSEQ | TGP | Path profile (Ts) | Path profile (us) | Maximum Cell radius (meter) | Use case |
|---|---|---|---|---|---|---|---|---|
| A0 | 1 | 144 | 2048 | 0 | 48 | 1.56 | 469 | TA is already known or Very small cell |
| A1 | 2 | 288 | 4096 | 0 | 96 | 3.13 | 938 | Small cell |
| A2 | 4 | 576 | 8192 | 0 | 144 | 4.69 | 2,109 | Normal cell |
| A3 | 6 | 864 | 12288 | 0 | 144 | 4.69 | 3,516 | Normal cell |
| B0 | 1 | 144 | 2048 | 0 | 48 | 1.56 | 469 | TA is already known or Very small cell |
| B1 | 2 | 192 | 4096 | 96 | 96 | 3.13 | 469 | Small cell |
| B2 | 4 | 360 | 8192 | 216 | 144 | 4.69 | 1,055 | Normal cell |
| B3 | 6 | 504 | 12288 | 360 | 144 | 4.69 | 1,758 | Normal cell |
| B4 | 12 | 936 | 24576 | 792 | 144 | 4.69 | 3,867 | Normal cell |
| C0 | 1 | 1240 | 2048 | 0 | 144 | 4.69 | 5300 | Normal cell |
| C1 | 2 | 1384 | 4096 | 0 | 144 | 4.69 | 6000 | Normal cell |
- Note 1: Unit is Ts, where Ts = 1/30.72MHz
- Note 2: PRACH preamble are aligned with OFDM symbol boundary for data with same numerology
- Note 3: Additional 16Ts for every 0.5ms should be included in TCP when RACH preamble is transmitted across 0.5ms boundary or from 0.5ms boundary
- Note 4: For format A, GP can be defined within the last RACH preamble among consecutively transmitted RACH preambles
- For 30/60/120 kHz subcarrier spacing, preamble format can be scaled according to subcarrier spacing.
- Ts =1/(2*30720) ms for 30 kHz subcarrier spacing
- Ts =1/(4*30720) ms for 60 kHz subcarrier spacing
- Ts =1/(8*30720) ms for 120 kHz subcarrier spacing
- Note that some of the formats may not be applicable to all subcarrier spacings