162 lines
5.7 KiB
C
162 lines
5.7 KiB
C
/* (C) 2018 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
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*
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* Author: Stefan Sperling <ssperling@sysmocom.de>
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*
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* All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#pragma once
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#include <stdbool.h>
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#include <stdint.h>
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#include <osmocom/core/timer.h>
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#include <osmocom/gsm/protocol/gsm_04_08.h>
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/*!
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* Access control class (ACC) ramping is used to slowly make the cell available to
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* an increasing number of MS. This avoids overload at startup time in cases where
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* a lot of MS would discover the new cell and try to connect to it all at once.
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*/
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#define ACC_RAMP_STEP_SIZE_MIN 1 /* allow at most 1 new ACC per ramp step */
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#define ACC_RAMP_STEP_SIZE_DEFAULT ACC_RAMP_STEP_SIZE_MIN
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#define ACC_RAMP_STEP_SIZE_MAX 10 /* allow all ACC in one step (effectively disables ramping) */
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#define ACC_RAMP_STEP_INTERVAL_MIN 30 /* 30 seconds */
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#define ACC_RAMP_STEP_INTERVAL_MAX 600 /* 10 minutes */
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/*!
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* Data structure used to manage ACC ramping. Please avoid setting or reading fields
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* in this structure directly. Use the accessor functions below instead.
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*/
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struct acc_ramp {
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struct gsm_bts *bts; /*!< backpointer to BTS using this ACC ramp */
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bool acc_ramping_enabled; /*!< whether ACC ramping is enabled */
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/*!
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* Bitmask which keeps track of access control classes that are currently denied
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* access. The function acc_ramp_apply() uses this mask to modulate bits from
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* octets 2 and 3 in RACH Control Parameters (see 3GPP 44.018 10.5.2.29).
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* Ramping is only concerned with ACCs 0-9. While any of the bits 0-9 is set,
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* the corresponding ACC is barred.
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* ACCs 11-15 should always be allowed, and ACC 10 denies emergency calls for
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* all ACCs from 0-9 inclusive; these ACCs are ignored in this implementation.
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*/
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uint16_t barred_accs;
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/*!
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* This controls the maximum number of ACCs to allow per ramping step (1 - 10).
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* The compile-time default value is ACC_RAMP_STEP_SIZE_DEFAULT.
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* This value can be changed by VTY configuration.
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* A value of ACC_RAMP_STEP_SIZE_MAX effectively disables ramping.
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*/
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unsigned int step_size;
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/*!
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* Ramping step interval in seconds.
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* This value depends on the current BTS channel load average, unless
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* it has been overridden by VTY configuration.
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*/
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unsigned int step_interval_sec;
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bool step_interval_is_fixed;
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struct osmo_timer_list step_timer;
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};
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/*!
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* Enable or disable ACC ramping.
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* When enabled, ramping begins once acc_ramp_start() is called.
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* When disabled, an ACC ramping process in progress will continue
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* unless acc_ramp_abort() is called as well.
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* \param[in] acc_ramp Pointer to acc_ramp structure.
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*/
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static inline void acc_ramp_set_enabled(struct acc_ramp *acc_ramp, bool enable)
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{
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acc_ramp->acc_ramping_enabled = enable;
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}
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/*!
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* Return true if ACC ramping is currently enabled, else false.
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* \param[in] acc_ramp Pointer to acc_ramp structure.
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*/
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static inline bool acc_ramp_is_enabled(struct acc_ramp *acc_ramp)
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{
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return acc_ramp->acc_ramping_enabled;
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}
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/*!
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* Return the current ACC ramp step size.
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* \param[in] acc_ramp Pointer to acc_ramp structure.
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*/
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static inline unsigned int acc_ramp_get_step_size(struct acc_ramp *acc_ramp)
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{
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return acc_ramp->step_size;
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}
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/*!
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* Return the current ACC ramp step interval (in seconds)
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* \param[in] acc_ramp Pointer to acc_ramp structure.
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*/
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static inline unsigned int acc_ramp_get_step_interval(struct acc_ramp *acc_ramp)
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{
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return acc_ramp->step_interval_sec;
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}
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/*!
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* If the step interval is dynamic, return true, else return false.
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* \param[in] acc_ramp Pointer to acc_ramp structure.
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*/
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static inline bool acc_ramp_step_interval_is_dynamic(struct acc_ramp *acc_ramp)
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{
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return !(acc_ramp->step_interval_is_fixed);
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}
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/*!
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* Return bitmasks which correspond to access control classes that are currently
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* denied access. Ramping is only concerned with those bits which control access
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* for ACCs 0-9, and any of the other bits will always be set to zero in these masks, i.e.
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* it is safe to OR these bitmasks with the corresponding fields in struct gsm48_rach_control.
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* \param[in] acc_ramp Pointer to acc_ramp structure.
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*/
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static inline uint8_t acc_ramp_get_barred_t2(struct acc_ramp *acc_ramp)
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{
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return ((acc_ramp->barred_accs >> 8) & 0x03);
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};
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static inline uint8_t acc_ramp_get_barred_t3(struct acc_ramp *acc_ramp)
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{
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return (acc_ramp->barred_accs & 0xff);
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}
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/*!
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* Potentially mark certain Access Control Classes (ACCs) as barred in accordance to ACC ramping.
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* \param[in] rach_control RACH control parameters in which barred ACCs will be configured.
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* \param[in] acc_ramp Pointer to acc_ramp structure.
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*/
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static inline void acc_ramp_apply(struct gsm48_rach_control *rach_control, struct acc_ramp *acc_ramp)
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{
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rach_control->t2 |= acc_ramp_get_barred_t2(acc_ramp);
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rach_control->t3 |= acc_ramp_get_barred_t3(acc_ramp);
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}
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void acc_ramp_init(struct acc_ramp *acc_ramp, struct gsm_bts *bts);
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int acc_ramp_set_step_size(struct acc_ramp *acc_ramp, unsigned int step_size);
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int acc_ramp_set_step_interval(struct acc_ramp *acc_ramp, unsigned int step_interval);
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void acc_ramp_set_step_interval_dynamic(struct acc_ramp *acc_ramp);
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void acc_ramp_trigger(struct acc_ramp *acc_ramp);
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void acc_ramp_abort(struct acc_ramp *acc_ramp);
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