Handle Immediate assignment reject
When RACH is received, PCU will generate the Immediate assignment reject
message if no resources are present. The encoding is done based on section
9.1.20 of 44.018 version 11.7.0 Release 11. This patch also includes the
test case to validate the generated Immediate assignment reject message.
This patch is integration tested on Osmo-trx setup with Ettus B210 board
and LG F70 MS with some simulation code changes in Osmo-pcu.
Change-Id: I3d33e2b9746fa4f338fad0e6b63b1c5f07de6f9b
diff --git a/src/encoding.cpp b/src/encoding.cpp
index fb80eeb..ca72b0f 100644
--- a/src/encoding.cpp
+++ b/src/encoding.cpp
@@ -242,6 +242,84 @@
}
/*
+ * Immediate assignment reject, sent on the CCCH/AGCH
+ * see GSM 44.018, 9.1.20 + 10.5.2.30
+ */
+int Encoding::write_immediate_assignment_reject(
+ bitvec *dest, uint16_t ra,
+ uint32_t ref_fn,
+ enum ph_burst_type burst_type)
+{
+ unsigned wp = 0;
+ int plen;
+ int i;
+
+ bitvec_write_field(dest, wp, 0x0, 4); // Skip Indicator
+ bitvec_write_field(dest, wp, 0x6, 4); // Protocol Discriminator
+ bitvec_write_field(dest, wp, 0x3A, 8); // Immediate Assign Message Type
+
+ // feature indicator
+ bitvec_write_field(dest, wp, 0x0, 1); // spare
+ bitvec_write_field(dest, wp, 0x0, 1); // spare
+ bitvec_write_field(dest, wp, 0x0, 1); // no cs
+ bitvec_write_field(dest, wp, 0x1, 1); // implicit detach for PS
+
+ bitvec_write_field(dest, wp, 0x0, 4); // Page Mode
+ /*
+ * 9.1.20.2 of 44.018 version 11.7.0 Release 11
+ * Filling of the message
+ * If necessary the request reference information element and the
+ * wait indication information element should be duplicated to
+ * fill the message.
+ * TODO: group rejection for multiple MS
+ */
+ for (i = 0; i < 4; i++) {
+ //10.5.2.30 Request Reference
+ if (((burst_type == GSM_L1_BURST_TYPE_ACCESS_1) ||
+ (burst_type == GSM_L1_BURST_TYPE_ACCESS_2))) {
+ //9.1.20.2a of 44.018 version 11.7.0 Release 11
+ bitvec_write_field(dest, wp, 0x7f, 8); /* RACH value */
+ } else {
+ bitvec_write_field(dest, wp, ra, 8); /* RACH value */
+ }
+
+ bitvec_write_field(dest, wp,
+ (ref_fn / (26 * 51)) % 32, 5); // T1'
+ bitvec_write_field(dest, wp, ref_fn % 51, 6); // T3
+ bitvec_write_field(dest, wp, ref_fn % 26, 5); // T2
+
+ /* TODO: Make it configurable */
+ bitvec_write_field(dest, wp, 20, 8); //Wait Indication 1
+ }
+
+ plen = wp / 8;
+
+ if ((wp % 8)) {
+ LOGP(DRLCMACUL, LOGL_ERROR, "Length of IMM.ASS.Rej without"
+ "rest octets is not multiple of 8 bits, PLEASE FIX!\n");
+ return -1;
+ }
+
+ // Extended RA
+ else if (((burst_type == GSM_L1_BURST_TYPE_ACCESS_1) ||
+ (burst_type == GSM_L1_BURST_TYPE_ACCESS_2))) {
+ //9.1.20.2a of 44.018 version 11.7.0 Release 11
+ uint8_t extended_ra = 0;
+
+ extended_ra = (ra & 0x1F);
+ bitvec_write_field(dest, wp, 0x1, 1);
+ bitvec_write_field(dest, wp, extended_ra, 5); /* Extended RA */
+ } else {
+ bitvec_write_field(dest, wp, 0x0, 1);
+ }
+ bitvec_write_field(dest, wp, 0x0, 1);
+ bitvec_write_field(dest, wp, 0x0, 1);
+ bitvec_write_field(dest, wp, 0x0, 1);
+
+ return plen;
+}
+
+/*
* Immediate assignment, sent on the CCCH/AGCH
* see GSM 04.08, 9.1.18 and GSM 44.018, 9.1.18 + 10.5.2.16
*/