Sunday, 14 February 2016

FDD-OMC-SON ANR Configuration Introduction


1. Description

Automatic Neighbor Relation (ANR) deployment function is one of the features in Self Organizing Network (SON). Enabling ANR function can help to optimize the LTE network neighbor relation. This document will give a brief introduction about ANR and then introduce how to enable this function.


2. introduction

2.1 Basic principle

The ANR function resides in the eNodeB. It consists of three modules: Neighbor Relation Table (NRT) Management Function, Neighbor Detection Function, and Neighbor Removal Function. The Neighbor Detection Function discovers new neighbors and adds them to the NRT; while the Neighbor Removal Function removes outdated NRs from the NRT. The OAM can add, remove and modify the NRs in the NRT and their attributes.
An NR in the context of ANR is defined as follows:
>>>The eNodeB controlling the source cell knows the ECGI/CGI and PCI of the target cell.
>>>The eNodeB has an entry in the NRT for the source cell identifying the target cell.
>>>The eNodeB has the attributes in this NRT entry defined.
Each NR has three attributes, and it has the following definitions:
>>>No Remove: If checked, the eNodeB shall not remove the NR from the NRT.
>>>No Handover (HO): If checked, the NR shall not be used by the eNodeB for handover reasons.
>>>No X2: If checked, the NR shall not use an X2 interface to initiate a handover with the target cell
 

2.2 ANR procedure

According to 3GPP TS 36.300, the intra-LTE/frequency ANR function works as follows:
 
1.    The UE of the eNodeB’s serving cell A sends a measurement report regarding cell B. This report contains Cell B’s PCI, but not its ECGI.
2.    The eNodeB instructs the UE, using the newly discovered PCI as parameter, to read the ECGI, the TAC, and all available PLMN ID(s) of the related neighbor cell.
3.    Upon obtaining cell B’s ECGI, the UE reports the detected ECGI to the serving cell (i.e. cell A). In addition the UE reports the TAC and all PLMN IDs that have been detected.
4.    The eNodeB decides to add this neighbor relation, and can use PCI and ECGI to look up a transport layer address to the new eNodeB, update the Neighbor Relation List, and if needed, set up a new X2 interface towards this eNodeB.
For inter-RAT and inter-Frequency ANR, each cell contains an Inter Frequency Search list. This list contains all frequencies that shall be searched. According to 3GPP TS 36.300, the inter-LTE/frequency ANR function works as follows:
 
1.    The eNodeB instructs a UE to look for neighbor cells in the target RATs/frequencies.
2.    The UE reports the PCI of the detected cells in the target RATs/frequencies. The definition and makeup of the PCI vary with different RATs.
3.    The eNodeB instructs the UE, using the newly discovered PCI as parameter, to read the CGI and other information of the detected neighbor cell.
4.    After the UE has read the requested information in the new cell, it reports the detected CGI and other information to the serving cell (i.e. cell A).
5.    The eNodeB updates its inter-RAT/inter-frequency Neighbor Relation Table. In the inter-frequency case and if needed, the eNodeB can use the PCI and ECGI for a new X2 interface setup towards this eNodeB.


3. ANR Configuration

In this chapter, it will give the configuration step for enabling ANR function.

3.1 DRX Switch

For ANR function, it needs to enable DRX in eNodeB.
 

3.2. UE capacity

For ANR function, it also needs to confirm the UE capacity. The UE should support DRX.
1.    Telnet the CC board.
2.    Type the command RnlcDcmDbgShowUeCap UeGid, where UeGid is the group ID of the UE and should be replaced with the actual ID.
3.    In the featureGroupIndicators message, check the value of the Indicators, which is a 8-digit hexadecimal number, as shown below.
 
4.    Convert the 8-digit hexadecimal number into a 32-digit binary number. If the converted number is less than 32 digits, add 0 in fron of the number.
5.    Check the fifth digit from the left, which indicates whether the UE supports long DRX. 0 means “not support” and 1 means “support”.
There is only one kind of UE (MF820D) in this project, this kind of UE can support DRX.

3.3. ANR template

Create an ANR template in SON, enable ANR set to ‘Auto’, others parameters leave as default.
 
Add Related Cell.

 

3.4 CGI Measurement

Confirm the CGI measurement parameters are OK. All the parameters in this part can leave as default.
Confirm CGI measurement Configuration for ANR, default it is 1000.
 
 Confirm the CGI measurement parameters are OK.




4. Conclusion

ANR function will add/remove neighbor relation. We can check whether it works or not in Neighbor Cell Management.


Budi Prasetyo

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