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diff --git a/include/osmocom/bsc/acc_ramp.h b/include/osmocom/bsc/acc_ramp.h
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+++ b/include/osmocom/bsc/acc_ramp.h
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+/* (C) 2018 Stefan Sperling <ssperling@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef _ACC_RAMP_H_
+#define _ACC_RAMP_H_
+
+#include <stdbool.h>
+
+#include <osmocom/core/timer.h>
+
+/*
+ * Access control class (ACC) ramping is used to slowly make the cell available to
+ * an increasing number of MS. This avoids overload at startup time in cases where
+ * a lot of MS would discover the new cell and try to connect to it all at once.
+ */
+
+enum acc_ramp_step_size {
+	ACC_RAMP_STEP_SIZE_MIN = 1, /* allow at most 1 new ACC per ramp step */
+	ACC_RAMP_STEP_SIZE_DEFAULT = ACC_RAMP_STEP_SIZE_MIN,
+	ACC_RAMP_STEP_SIZE_MAX = 10, /* allow all ACC in one step (disables ramping) */
+};
+
+enum acc_ramp_step_interval {
+	ACC_RAMP_STEP_INTERVAL_MIN = 1,		/* 1 second */
+	ACC_RAMP_STEP_INTERVAL_DEFAULT = 60,	/* 1 minute */
+	ACC_RAMP_STEP_INTERVAL_MAX = 600,	/* 10 minutes */
+};
+
+struct acc_ramp {
+	/*
+	 * Bitmasks which keep track of access control classes that are currently
+	 * denied access to this BTS. These masks modulate bits from octets 2 and 3
+	 * of the RACH Control Parameters (see 3GPP 44.018 10.5.2.29).
+	 * While a bit in these masks is set, the corresponding ACC is barred.
+	 * Note that t2 contains bits for classes 11-15 which should always be allowed,
+	 * and a bit which denies emergency calls for all ACCs from 0-9 inclusive.
+	 * Ramping is only concerned with those bits which control access for ACCs 0-9.
+	 */
+	uint8_t barred_t2;
+	uint8_t barred_t3;
+
+	/*
+	 * This controls the maximum number of ACCs to allow per ramping step (1 - 10).
+	 * The compile-time default value is ACC_RAMP_STEP_SIZE_DEFAULT.
+	 * This value can be changed by VTY configuration.
+	 * A value of ACC_RAMP_STEP_SIZE_MAX effectively disables ramping.
+	 */
+	enum acc_ramp_step_size step_size;
+
+	/*
+	 * Ramping step interval in seconds.
+	 * This value depends on the current BTS channel load average, unless
+	 * it has been overriden by VTY configuration.
+	 */
+	unsigned int step_interval_sec;
+	bool step_interval_is_fixed;
+	struct osmo_timer_list step_timer;
+};
+
+#endif /* _ACC_RAMP_H_ */