Testing documentation for LTE cell selection

doc/models/Makefile

@@ -115,6 +115,8 @@ SOURCEFIGS = \
 	$(SRC)/lte/doc/source/figures/ue-meas-piecewise-a1.dia \
 	$(SRC)/lte/doc/source/figures/ue-meas-piecewise-a1-hys.dia \
 	$(SRC)/lte/doc/source/figures/lte-cell-selection.dia \
+	$(SRC)/lte/doc/source/figures/lte-cell-selection-open-access.dia \
+	$(SRC)/lte/doc/source/figures/lte-cell-selection-closed-access.dia \
 	$(SRC)/lte/doc/source/figures/lena-dual-stripe.eps \
 	$(SRC)/lte/doc/source/figures/lte-mcs-index.eps \
 	$(SRC)/lte/doc/source/figures/lenaThrTestCase1.eps \
@@ -254,6 +256,8 @@ IMAGES_EPS = \
 	$(FIGURES)/ue-meas-piecewise-a1.eps \
 	$(FIGURES)/ue-meas-piecewise-a1-hys.eps \
 	$(FIGURES)/lte-cell-selection.eps \
+	$(FIGURES)/lte-cell-selection-open-access.eps \
+	$(FIGURES)/lte-cell-selection-closed-access.eps \
 	$(FIGURES)/lena-dual-stripe.eps \
 	$(FIGURES)/lte-mcs-index.eps \
 	$(FIGURES)/lenaThrTestCase1.eps \

src/lte/doc/Makefile

@@ -35,7 +35,9 @@ IMAGES_DIA = \
 	$(FIGURES)/ue-meas-piecewise-motion.dia \
 	$(FIGURES)/ue-meas-piecewise-a1.dia \
 	$(FIGURES)/ue-meas-piecewise-a1-hys.dia \
-	$(FIGURES)/lte-cell-selection.dia
+	$(FIGURES)/lte-cell-selection.dia \
+	$(FIGURES)/lte-cell-selection-open-access.dia \
+	$(FIGURES)/lte-cell-selection-closed-access.dia
 
 
 # specify eps figures from which .png and .pdf figures need to be built

src/lte/doc/source/figures/lte-ue-rrc-states.dot

@@ -11,7 +11,7 @@ CONNECTED_HANDOVER [shape="box",width=4]
 
 
 IDLE_CELL_SELECTION -> IDLE_WAIT_SYSTEM_INFO [label="cell ID enforced\nby upper layers"]
-IDLE_CELL_SELECTION -> IDLE_CAMPED_NORMALLY [label="cell selection\nsuccessful"]
+IDLE_CELL_SELECTION -> IDLE_WAIT_SYSTEM_INFO [label="cell selection\nsuccessful"]
 IDLE_WAIT_SYSTEM_INFO -> IDLE_CAMPED_NORMALLY [label="rx MIB + SIB2"]
 IDLE_CAMPED_NORMALLY -> IDLE_RANDOM_ACCESS [label="connection request\nby upper layers"]
 IDLE_RANDOM_ACCESS -> IDLE_CONNECTING [label="random access\nsuccessful"]

src/lte/doc/source/lte-design.rst

@@ -1969,6 +1969,7 @@ model (see :ref:`sec-rrc-protocol-models`) and no transmission error.
 .. _fig-lte-cell-selection:
 
 .. figure:: figures/lte-cell-selection.*
+   :scale: 80 %
    :align: center
 
    Sample runs of initial cell selection in UE and timing of related events
@@ -2311,8 +2312,7 @@ Section 5.5.4 of [TS36331]_.
 Event-based trigger can be further configured by introducing hysteresis and
 time-to-trigger. *Hysteresis* (:math:`Hys`) defines the distance between the
 entering and leaving conditions in dB. Similarly, *time-to-trigger* introduces
-delay to both entering and leaving conditions, but as a unit of time. Section
-
+delay to both entering and leaving conditions, but as a unit of time.
 
 *Periodical* type of reporting trigger is not supported, but can be easily
 replicated using event-based trigger. This can be done by configuring the

src/lte/doc/source/lte-references.rst

@@ -40,6 +40,7 @@ References
 
 .. [TS36423] 3GPP TS 36.423 "E-UTRAN X2 application protocol (X2AP)"
 
+.. [TS36922] 3GPP TS 36.922 "E-UTRA TDD Home eNode B (HeNB) Radio Frequency (RF) requirements analysis"
 
 .. [R1-081483] 3GPP R1-081483 `Conveying MCS and TB size via PDCCH <http://www.3gpp.org/ftp/tsg_ran/WG1_RL1/TSGR1_52b/Docs/R1-081483.zip>`_
 

src/lte/doc/source/lte-testing.rst

@@ -1012,7 +1012,70 @@ each UE:
 Initial cell selection
 ----------------------
 
-(to be expanded)
+The test suite `lte-cell-selection` is responsible for verifying the
+:ref:`sec-initial-cell-selection` procedure. 3 short test cases are included in
+the suite.
+
+Each test case is a simulation of a small network of 4 cells. Each eNodeB is
+equipped with directional antenna (parabolic model) and is arranged so that some
+of their coverage are overlapping with other eNodeB. They are configured using
+the same Tx Power. Several static UEs are then placed at predefined locations
+and with initial cell selection procedure enabled. Thus the UEs enters the
+simulation without being attached to any cell.
+
+At the end of the simulation, the test verifies that every UE is attached to the
+right cell. Moreover, the test also ensures that the UE is properly connected
+(i.e. its final state is `CONNECTED_NORMALLY`).
+
+The first test case is a scenario with open access cells, i.e. without Closed
+Subscriber Group (CSG). The result shows that the UEs are attaching to the
+expected cells, as shown in Figure :ref:`fig-lte-cell-selection-open-access`
+below. Note that the grey area below each eNodeB only indicates the rough
+directivity of the antenna, while the actual cell coverage is much wider and
+larger.
+
+.. _fig-lte-cell-selection-open-access:
+
+.. figure:: figures/lte-cell-selection-open-access.*
+   :scale: 80 %
+   :align: center
+
+   Sample result of cell selection in open access scenario
+
+The second and third cases incorporate CSG into the simulation. 2 out of 4 cells
+become a single CSG and implement closed access, while the other 2 cells stay
+open. In a similar way, half of the UEs are configured as members of the CSG,
+while the rest are not. The resulting simulation is depicted in Figure
+:ref:`fig-lte-cell-selection-closed-access` below.
+
+.. _fig-lte-cell-selection-closed-access:
+
+.. figure:: figures/lte-cell-selection-closed-access.*
+   :scale: 80 %
+   :align: center
+
+   Sample result of cell selection in closed access scenario
+
+It shows that CSG members may attach to either CSG or non-CSG cells, and simply
+choose the stronger one. On the other hand, non-members can only attach to
+non-CSG cells, even when they are actually receive stronger signal from a CSG
+cell.
+
+Note that a real life CSG deployment typically implements interference
+coordination. Section 5.1 of [TS36922]_ describes frequency, time, and spatial
+partitioning as possible approaches to interference coordination. However, none
+of these approaches are implemented in this test suite.
+
+As "expected", interference issues occur in the simulation. The issue is more
+apparent in the CSG scenario, as experienced by the UE (highlighted in Figure
+:ref:`fig-lte-cell-selection-closed-access` above) which is well positioned
+within the coverage of a CSG cell but not a member of the CSG. After the UE
+fails to attach to the CSG cell, the cell becomes a major interference to the UE
+and causing difficulties to the UE in attempting to attach to the closest
+non-CSG cell. In other words, the UE is experiencing low SINR when receiving
+transmission from the non-CSG cell. As a result, the UE takes longer time to
+attach to the non-CSG cell because it often fails to receive system information
+messages (e.g. MIB, SIB1, and SIB2) from the non-CSG cell.
 
 
 

src/lte/test/lte-test-cell-selection.cc

@@ -304,13 +304,7 @@ LteCellSelectionTestCase::DoRun ()
     } // end of if (m_isEpcMode)
   else
     {
-      // // TODO remove this
-      // lteHelper->Attach (ueDevs, enbDevs.Get (0));
-      //
-      // // Activate an EPS bearer
-      // enum EpsBearer::Qci q = EpsBearer::GBR_CONV_VOICE;
-      // EpsBearer bearer (q);
-      // lteHelper->ActivateDataRadioBearer (ueDevs, bearer);
+      NS_FATAL_ERROR ("No support yet for LTE_only simulations");
     }
 
   // Connect to trace sources in UEs