A Discrete-Event Network Simulator
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a3-rsrp-handover-algorithm.cc
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1/*
2 * Copyright (c) 2013 Budiarto Herman
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation;
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License
14 * along with this program; if not, write to the Free Software
15 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
16 *
17 * Author: Budiarto Herman <budiarto.herman@magister.fi>
18 *
19 */
20
22
23#include "lte-common.h"
24
25#include <ns3/double.h>
26#include <ns3/log.h>
27
28#include <algorithm>
29#include <list>
30
31namespace ns3
32{
33
34NS_LOG_COMPONENT_DEFINE("A3RsrpHandoverAlgorithm");
35
36NS_OBJECT_ENSURE_REGISTERED(A3RsrpHandoverAlgorithm);
37
39 : m_handoverManagementSapUser(nullptr)
40{
41 NS_LOG_FUNCTION(this);
44}
45
47{
48 NS_LOG_FUNCTION(this);
49}
50
53{
54 static TypeId tid =
55 TypeId("ns3::A3RsrpHandoverAlgorithm")
57 .SetGroupName("Lte")
58 .AddConstructor<A3RsrpHandoverAlgorithm>()
59 .AddAttribute(
60 "Hysteresis",
61 "Handover margin (hysteresis) in dB "
62 "(rounded to the nearest multiple of 0.5 dB)",
63 DoubleValue(3.0),
65 MakeDoubleChecker<uint8_t>(0.0, 15.0)) // Hysteresis IE value range is [0..30] as
66 // per Section 6.3.5 of 3GPP TS 36.331
67 .AddAttribute("TimeToTrigger",
68 "Time during which neighbour cell's RSRP "
69 "must continuously higher than serving cell's RSRP "
70 "in order to trigger a handover",
71 TimeValue(MilliSeconds(256)), // 3GPP time-to-trigger median value as per
72 // Section 6.3.5 of 3GPP TS 36.331
75 return tid;
76}
77
78void
80{
81 NS_LOG_FUNCTION(this << s);
83}
84
87{
88 NS_LOG_FUNCTION(this);
90}
91
92void
94{
95 NS_LOG_FUNCTION(this);
96
98 NS_LOG_LOGIC(this << " requesting Event A3 measurements"
99 << " (hysteresis=" << (uint16_t)hysteresisIeValue << ")"
100 << " (ttt=" << m_timeToTrigger.As(Time::MS) << ")");
101
102 LteRrcSap::ReportConfigEutra reportConfig;
104 reportConfig.a3Offset = 0;
105 reportConfig.hysteresis = hysteresisIeValue;
107 reportConfig.reportOnLeave = false;
111
113}
114
115void
117{
118 NS_LOG_FUNCTION(this);
120}
121
122void
124{
125 NS_LOG_FUNCTION(this << rnti << (uint16_t)measResults.measId);
126
127 if (std::find(begin(m_measIds), end(m_measIds), measResults.measId) == std::end(m_measIds))
128 {
129 NS_LOG_WARN("Ignoring measId " << (uint16_t)measResults.measId);
130 return;
131 }
132
133 if (measResults.haveMeasResultNeighCells && !measResults.measResultListEutra.empty())
134 {
135 uint16_t bestNeighbourCellId = 0;
136 uint8_t bestNeighbourRsrp = 0;
137
138 for (auto it = measResults.measResultListEutra.begin();
139 it != measResults.measResultListEutra.end();
140 ++it)
141 {
142 if (it->haveRsrpResult)
143 {
144 if ((bestNeighbourRsrp < it->rsrpResult) && IsValidNeighbour(it->physCellId))
145 {
146 bestNeighbourCellId = it->physCellId;
147 bestNeighbourRsrp = it->rsrpResult;
148 }
149 }
150 else
151 {
152 NS_LOG_WARN("RSRP measurement is missing from cell ID " << it->physCellId);
153 }
154 }
155
156 if (bestNeighbourCellId > 0)
157 {
158 NS_LOG_LOGIC("Trigger Handover to cellId " << bestNeighbourCellId);
159 NS_LOG_LOGIC("target cell RSRP " << (uint16_t)bestNeighbourRsrp);
160 NS_LOG_LOGIC("serving cell RSRP " << (uint16_t)measResults.measResultPCell.rsrpResult);
161
162 // Inform eNodeB RRC about handover
163 m_handoverManagementSapUser->TriggerHandover(rnti, bestNeighbourCellId);
164 }
165 }
166 else
167 {
169 this << " Event A3 received without measurement results from neighbouring cells");
170 }
171
172} // end of DoReportUeMeas
173
174bool
176{
177 NS_LOG_FUNCTION(this << cellId);
178
179 /**
180 * \todo In the future, this function can be expanded to validate whether the
181 * neighbour cell is a valid target cell, e.g., taking into account the
182 * NRT in ANR and whether it is a CSG cell with closed access.
183 */
184
185 return true;
186}
187
188} // end of namespace ns3
Implementation of the strongest cell handover algorithm, based on RSRP measurements and Event A3.
bool IsValidNeighbour(uint16_t cellId)
Determines if a neighbour cell is a valid destination for handover.
double m_hysteresisDb
The Hysteresis attribute.
LteHandoverManagementSapUser * m_handoverManagementSapUser
Interface to the eNodeB RRC instance.
static TypeId GetTypeId()
Get the type ID.
LteHandoverManagementSapProvider * m_handoverManagementSapProvider
Receive API calls from the eNodeB RRC instance.
Time m_timeToTrigger
The TimeToTrigger attribute.
void DoDispose() override
Destructor implementation.
friend class MemberLteHandoverManagementSapProvider< A3RsrpHandoverAlgorithm >
let the forwarder class access the protected and private members
A3RsrpHandoverAlgorithm()
Creates a strongest cell handover algorithm instance.
void DoInitialize() override
Initialize() implementation.
LteHandoverManagementSapProvider * GetLteHandoverManagementSapProvider() override
Export the "provider" part of the Handover Management SAP interface.
std::vector< uint8_t > m_measIds
The expected measurement identity for A3 measurements.
void SetLteHandoverManagementSapUser(LteHandoverManagementSapUser *s) override
Set the "user" part of the Handover Management SAP interface that this handover algorithm instance wi...
void DoReportUeMeas(uint16_t rnti, LteRrcSap::MeasResults measResults) override
Implementation of LteHandoverManagementSapProvider::ReportUeMeas.
This class can be used to hold variables of floating point type such as 'double' or 'float'.
Definition: double.h:42
static uint8_t ActualHysteresis2IeValue(double hysteresisDb)
Returns the IE value of hysteresis.
Definition: lte-common.cc:294
The abstract base class of a handover algorithm that operates using the Handover Management SAP inter...
Service Access Point (SAP) offered by the handover algorithm instance to the eNodeB RRC instance.
Service Access Point (SAP) offered by the eNodeB RRC instance to the handover algorithm instance.
virtual void TriggerHandover(uint16_t rnti, uint16_t targetCellId)=0
Instruct the eNodeB RRC entity to prepare a handover.
virtual std::vector< uint8_t > AddUeMeasReportConfigForHandover(LteRrcSap::ReportConfigEutra reportConfig)=0
Request a certain reporting configuration to be fulfilled by the UEs attached to the eNodeB entity.
virtual void DoInitialize()
Initialize() implementation.
Definition: object.cc:451
int64_t GetMilliSeconds() const
Get an approximation of the time stored in this instance in the indicated unit.
Definition: nstime.h:408
TimeWithUnit As(const Unit unit=Time::AUTO) const
Attach a unit to a Time, to facilitate output in a specific unit.
Definition: time.cc:415
@ MS
millisecond
Definition: nstime.h:117
AttributeValue implementation for Time.
Definition: nstime.h:1413
a unique identifier for an interface.
Definition: type-id.h:59
TypeId SetParent(TypeId tid)
Set the parent TypeId.
Definition: type-id.cc:932
Ptr< const AttributeAccessor > MakeDoubleAccessor(T1 a1)
Definition: double.h:43
Ptr< const AttributeChecker > MakeTimeChecker()
Helper to make an unbounded Time checker.
Definition: nstime.h:1434
Ptr< const AttributeAccessor > MakeTimeAccessor(T1 a1)
Definition: nstime.h:1414
#define NS_LOG_COMPONENT_DEFINE(name)
Define a Log component with a specific name.
Definition: log.h:202
#define NS_LOG_LOGIC(msg)
Use NS_LOG to output a message of level LOG_LOGIC.
Definition: log.h:282
#define NS_LOG_FUNCTION(parameters)
If log level LOG_FUNCTION is enabled, this macro will output all input parameters separated by ",...
#define NS_LOG_WARN(msg)
Use NS_LOG to output a message of level LOG_WARN.
Definition: log.h:261
#define NS_OBJECT_ENSURE_REGISTERED(type)
Register an Object subclass with the TypeId system.
Definition: object-base.h:46
Time MilliSeconds(uint64_t value)
Construct a Time in the indicated unit.
Definition: nstime.h:1338
Every class exported by the ns3 library is enclosed in the ns3 namespace.
uint8_t rsrpResult
the RSRP result
Definition: lte-rrc-sap.h:674
MeasResults structure.
Definition: lte-rrc-sap.h:717
uint8_t measId
measure ID
Definition: lte-rrc-sap.h:718
bool haveMeasResultNeighCells
have measure result neighbor cells
Definition: lte-rrc-sap.h:720
std::list< MeasResultEutra > measResultListEutra
measure result list eutra
Definition: lte-rrc-sap.h:721
MeasResultPCell measResultPCell
measurement result primary cell
Definition: lte-rrc-sap.h:719
Specifies criteria for triggering of an E-UTRA measurement reporting event.
Definition: lte-rrc-sap.h:373
bool reportOnLeave
Indicates whether or not the UE shall initiate the measurement reporting procedure when the leaving c...
Definition: lte-rrc-sap.h:399
enum ns3::LteRrcSap::ReportConfigEutra::@62 eventId
Event enumeration.
uint8_t hysteresis
Parameter used within the entry and leave condition of an event triggered reporting condition.
Definition: lte-rrc-sap.h:407
@ RSRP
Reference Signal Received Power.
Definition: lte-rrc-sap.h:425
@ EVENT_A3
Event A3: Neighbour becomes amount of offset better than PCell.
Definition: lte-rrc-sap.h:386
enum ns3::LteRrcSap::ReportConfigEutra::@65 reportInterval
Report interval enumeration.
enum ns3::LteRrcSap::ReportConfigEutra::@63 triggerQuantity
Trigger type enumeration.
int8_t a3Offset
Offset value for Event A3.
Definition: lte-rrc-sap.h:403
uint16_t timeToTrigger
Time during which specific criteria for the event needs to be met in order to trigger a measurement r...
Definition: lte-rrc-sap.h:411