Notes
A MAC PDU which is
part of Random Access Response (RAR) consists of a MAC header and zero or more
MAC Random Access Responses (MAC RAR) and optionally padding.
The MAC header is of
variable size.
A MAC PDU (RAR)
header consists of one subheader for each MAC RAR and only on subheader for
Backoff Indicator.
The subheader for
Backoff Indicator, if included, is always the first subheader.
There can be one or
more MAC RARs in the MAC PDU (RAR).
Padding may occur
after the last MAC RAR. Presence and length of padding is implicit based on TB
size, size of MAC header and number of RARs.
Each MAC RAR has a fixed size of 6 Bytes which consists of 1 reserved bit, 11-bit Timing Advance Command, 20-bit UL Grant, and 16-bit Temporary C-RNTI.
Reference: 3GPP TS 36.321 and 36.213
hi kumar , 100 ue's send rach req using same preamble or diff preamble's same subframefthen how many ue's get RA response.
ReplyDeleteHi Kumar,
ReplyDeleteI used your decoder to decode the following MAC RAR
4f 00 a1 98 0c 00 3d
The result shows that hopping flag is 1 but as I understand it should be 0. Could you please clarify ?
Hello,
DeleteThanks for spotting the bug. It was an incorrect array index used in the script. Now I have corrected it.
Hi,
ReplyDeleteWhat if 2 UE sends same random number in msg3.
What would happen in this case ?
The random number is a 40-bit number so the chances of generating the same random nummber by 2 UEs is almost zero.
DeleteHi , How to get information of MAC RAR from EnodeB ? which traces should I active on EnodeB?
ReplyDeleteBI is part of RAR response. If UE sends RACH preamble and not received any RAR, how will UE get BI to figure out when I can send next RACH preamble?
ReplyDelete