Change in osmocom-bb[master]: trxcon: fix tail bits at the front of Access burst

[Piotr Krysik]

Piotr Krysik has uploaded this change for review. ( https://gerrit.osmocom.org/10001


Change subject: trxcon: fix tail bits at the front of Access burst
......................................................................

trxcon: fix tail bits at the front of Access burst

Currently Access Burst generated by trxcon
has 8 zero bits at the beginning. According to
the 3GPP 05.02 specification (Chapter 5.2.7
Access burst) custom 8-bit extended tail bits
sequence should be used:
(BN0, BN1, BN2 ... BN7) = (0,0,1,1,1,0,1,0)

After this fix trxcon sets correct 8-bit
sequence at the front of Access burst.

Change-Id: I1f624e783de6c585d2e292965c9e5810b0a4f27d
---
M src/host/trxcon/sched_lchan_rach.c
1 file changed, 10 insertions(+), 1 deletion(-)



  git pull ssh://gerrit.osmocom.org:29418/osmocom-bb refs/changes/01/10001/1

diff --git a/src/host/trxcon/sched_lchan_rach.c b/src/host/trxcon/sched_lchan_rach.c
index 2a09a37..3f6e2e1 100644
--- a/src/host/trxcon/sched_lchan_rach.c
+++ b/src/host/trxcon/sched_lchan_rach.c
@@ -42,6 +42,15 @@
 #include "l1ctl.h"
 
 /**
+ * 8-bit RACH extended tail bits
+ * GSM 05.02 Chapter 5.2.7 Access burst (AB)
+ */
+
+static ubit_t rach_ext_tail_bits[] = {
+	0, 0, 1, 1, 1, 0, 1, 0,
+};
+
+/**
  * 41-bit RACH synchronization sequence
  * GSM 05.02 Chapter 5.2.7 Access burst (AB)
  */
@@ -79,7 +88,7 @@
 	}
 
 	/* Compose RACH burst */
-	memset(burst, 0, 8); /* TB */
+	memcpy(burst, rach_ext_tail_bits, 8); /* TB */
 	memcpy(burst + 8, rach_synch_seq, 41); /* sync seq */
 	memcpy(burst + 49, payload, 36); /* payload */
 	memset(burst + 85, 0, 63); /* TB + GP */

-- 
To view, visit https://gerrit.osmocom.org/10001
To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings

Gerrit-Project: osmocom-bb
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: I1f624e783de6c585d2e292965c9e5810b0a4f27d
Gerrit-Change-Number: 10001
Gerrit-PatchSet: 1
Gerrit-Owner: Piotr Krysik <ptrkrysik at gmail.com>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osmocom.org/pipermail/gerrit-log/attachments/20180716/1b53309b/attachment.htm>