si: Add a config option to disable SI2ter/SI2bis/SI5ter/SI5bis messages

The iPhone5 (US) appears to have some issues with the SIs generated,
or the nanoBTS is not sending them correctly.

Add a configurable hack to put all bands into the SI2/SI5 message.
It is enabled by the bts VTY command 'force-combined-si'.

This is a quick change without much reflection and watching for side
effects. I have verfied that a network with ARFCN 134 and neighbors
ARFCN 130 and 512 do not get generate the SI2ter and announce everything
inside the SI2.

This patch is conceptually based on 'si: Add a hack to disable
SI2ter/SI2bis/SI5ter/SI5bis messages' (692daaf2d2).

Ticket: OW#1062
Sponsored-by: On-Waves ehf

openbsc/include/openbsc/gsm_data_shared.h

@@ -676,6 +676,9 @@ struct gsm_bts {
 	int num_trx;
 	struct llist_head trx_list;
 
+	/* SI compatibility hacks */
+	int force_combined_si;
+
 #ifdef ROLE_BSC
 	/* Abis NM queue */
 	struct llist_head abis_queue;

openbsc/src/libbsc/bsc_vty.c

@@ -645,6 +645,9 @@ static void config_write_bts_single(struct vty *vty, struct gsm_bts *bts)
 	if (bts->excl_from_rf_lock)
 		vty_out(vty, "  rf-lock-exclude%s", VTY_NEWLINE);
 
+	vty_out(vty, "  %sforce-combined-si%s",
+		bts->force_combined_si ? "" : "no ", VTY_NEWLINE);
+
 	config_write_bts_model(vty, bts);
 }
 
@@ -2667,6 +2670,28 @@ DEFUN(cfg_bts_no_excl_rf_lock,
 	return CMD_SUCCESS;
 }
 
+#define FORCE_COMB_SI_STR "Force the generation of a single SI (no ter/bis)\n"
+
+DEFUN(cfg_bts_force_comb_si,
+      cfg_bts_force_comb_si_cmd,
+      "force-combined-si",
+      FORCE_COMB_SI_STR)
+{
+	struct gsm_bts *bts = vty->index;
+	bts->force_combined_si = 1;
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_bts_no_force_comb_si,
+      cfg_bts_no_force_comb_si_cmd,
+      "no force-combined-si",
+      NO_STR FORCE_COMB_SI_STR)
+{
+	struct gsm_bts *bts = vty->index;
+	bts->force_combined_si = 0;
+	return CMD_SUCCESS;
+}
+
 static void _get_codec_from_arg(struct vty *vty, int argc, const char *argv[])
 {
 	struct gsm_bts *bts = vty->index;
@@ -3331,6 +3356,8 @@ int bsc_vty_init(const struct log_info *cat)
 	install_element(BTS_NODE, &cfg_bts_si5_neigh_cmd);
 	install_element(BTS_NODE, &cfg_bts_excl_rf_lock_cmd);
 	install_element(BTS_NODE, &cfg_bts_no_excl_rf_lock_cmd);
+	install_element(BTS_NODE, &cfg_bts_force_comb_si_cmd);
+	install_element(BTS_NODE, &cfg_bts_no_force_comb_si_cmd);
 	install_element(BTS_NODE, &cfg_bts_codec0_cmd);
 	install_element(BTS_NODE, &cfg_bts_codec1_cmd);
 	install_element(BTS_NODE, &cfg_bts_codec2_cmd);

openbsc/src/libbsc/system_information.c

@@ -70,8 +70,11 @@ static int is_dcs_net(const struct gsm_bts *bts)
 static int use_arfcn(const struct gsm_bts *bts, const int bis, const int ter,
 			const int pgsm, const int arfcn)
 {
+	if (bts->force_combined_si)
+		return !bis && !ter;
 	if (!bis && !ter && band_compatible(bts, arfcn))
 		return 1;
+	/* Correct but somehow broken with either the nanoBTS or the iPhone5 */
 	if (bis && pgsm && band_compatible(bts, arfcn) && (arfcn < 1 || arfcn > 124))
 		return 1;
 	if (ter && !band_compatible(bts, arfcn))

openbsc/tests/vty_test_runner.py

@@ -173,6 +173,24 @@ class TestVTYNITB(TestVTYGenericBSC):
         self.assertEquals(res.find('periodic location update 60'), -1)
         self.assert_(res.find('no periodic location update') > 0)
 
+    def testEnableDisableSiHacks(self):
+        self.vty.enable()
+        self.vty.command("configure terminal")
+        self.vty.command("network")
+        self.vty.command("bts 0")
+
+        # Enable periodic lu..
+        self.vty.verify("force-combined-si", [''])
+        res = self.vty.command("write terminal")
+        self.assert_(res.find('  force-combined-si') > 0)
+        self.assertEquals(res.find('no force-combined-si'), -1)
+
+        # Now disable it..
+        self.vty.verify("no force-combined-si", [''])
+        res = self.vty.command("write terminal")
+        self.assertEquals(res.find('  force-combined-si'), -1)
+        self.assert_(res.find('no force-combined-si') > 0)
+
     def testRachAccessControlClass(self):
         self.vty.enable()
         self.vty.command("configure terminal")