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/* (C) 2018 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
*
* Author: 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/>.
*
*/
#pragma once
#include <stdbool.h>
#include <stdint.h>
#include <osmocom/core/timer.h>
#include <osmocom/gsm/protocol/gsm_04_08.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.
*/
#define ACC_RAMP_STEP_SIZE_MIN 1 /* allow at most 1 new ACC per ramp step */
#define ACC_RAMP_STEP_SIZE_DEFAULT ACC_RAMP_STEP_SIZE_MIN
#define ACC_RAMP_STEP_SIZE_MAX 10 /* allow all ACC in one step (effectively disables ramping) */
#define ACC_RAMP_STEP_INTERVAL_MIN 30 /* 30 seconds */
#define ACC_RAMP_STEP_INTERVAL_MAX 600 /* 10 minutes */
/*!
* Data structure used to manage ACC ramping. Please avoid setting or reading fields
* in this structure directly. Use the accessor functions below instead.
*/
struct acc_ramp {
struct gsm_bts *bts; /*!< backpointer to BTS using this ACC ramp */
bool acc_ramping_enabled; /*!< whether ACC ramping is enabled */
/*!
* Bitmask which keeps track of access control classes that are currently denied
* access. The function acc_ramp_apply() uses this mask to modulate bits from
* octets 2 and 3 in RACH Control Parameters (see 3GPP 44.018 10.5.2.29).
* Ramping is only concerned with ACCs 0-9. While any of the bits 0-9 is set,
* the corresponding ACC is barred.
* ACCs 11-15 should always be allowed, and ACC 10 denies emergency calls for
* all ACCs from 0-9 inclusive; these ACCs are ignored in this implementation.
*/
uint16_t barred_accs;
/*!
* 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.
*/
unsigned int 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;
};
/*!
* Return true if ACC ramping is currently enabled, else false.
* \param[in] acc_ramp Pointer to acc_ramp structure.
*/
static inline bool acc_ramp_is_enabled(struct acc_ramp *acc_ramp)
{
return acc_ramp->acc_ramping_enabled;
}
/*!
* Return the current ACC ramp step size.
* \param[in] acc_ramp Pointer to acc_ramp structure.
*/
static inline unsigned int acc_ramp_get_step_size(struct acc_ramp *acc_ramp)
{
return acc_ramp->step_size;
}
/*!
* Return the current ACC ramp step interval (in seconds)
* \param[in] acc_ramp Pointer to acc_ramp structure.
*/
static inline unsigned int acc_ramp_get_step_interval(struct acc_ramp *acc_ramp)
{
return acc_ramp->step_interval_sec;
}
/*!
* If the step interval is dynamic, return true, else return false.
* \param[in] acc_ramp Pointer to acc_ramp structure.
*/
static inline bool acc_ramp_step_interval_is_dynamic(struct acc_ramp *acc_ramp)
{
return !(acc_ramp->step_interval_is_fixed);
}
/*!
* Return bitmasks which correspond to access control classes that are currently
* denied access. Ramping is only concerned with those bits which control access
* for ACCs 0-9, and any of the other bits will always be set to zero in these masks, i.e.
* it is safe to OR these bitmasks with the corresponding fields in struct gsm48_rach_control.
* \param[in] acc_ramp Pointer to acc_ramp structure.
*/
static inline uint8_t acc_ramp_get_barred_t2(struct acc_ramp *acc_ramp)
{
return ((acc_ramp->barred_accs >> 8) & 0x03);
};
static inline uint8_t acc_ramp_get_barred_t3(struct acc_ramp *acc_ramp)
{
return (acc_ramp->barred_accs & 0xff);
}
/*!
* Potentially mark certain Access Control Classes (ACCs) as barred in accordance to ACC ramping.
* \param[in] rach_control RACH control parameters in which barred ACCs will be configured.
* \param[in] acc_ramp Pointer to acc_ramp structure.
*/
static inline void acc_ramp_apply(struct gsm48_rach_control *rach_control, struct acc_ramp *acc_ramp)
{
rach_control->t2 |= acc_ramp_get_barred_t2(acc_ramp);
rach_control->t3 |= acc_ramp_get_barred_t3(acc_ramp);
}
void acc_ramp_init(struct acc_ramp *acc_ramp, bool enable, struct gsm_bts *bts);
int acc_ramp_set_step_size(struct acc_ramp *acc_ramp, unsigned int step_size);
int acc_ramp_set_step_interval(struct acc_ramp *acc_ramp, unsigned int step_interval);
void acc_ramp_set_step_interval_dynamic(struct acc_ramp *acc_ramp);
void acc_ramp_start(struct acc_ramp *acc_ramp);
void acc_ramp_abort(struct acc_ramp *acc_ramp);
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