Tems_UMTS_dropped & blocked call specifications

Topics: Trigraph, Drop, The Network Pages: 8 (2410 words) Published: September 24, 2013


RANT Dropped and Blocked Calls Classification Summary
(WCDMA Network MTN South Africa)

1 Introduction 2
2 Dropped Calls Classification3
2.1 Missing Neighbours3
2.2 Poor Coverage4
2.3 Bad Radio Environment5
2.4 Congestion6
2.5 Not Radio7
2.6 Equipment Fault8
3 Blocked Calls Classification9
3.1 Missing Neighbour10
3.2 Poor RF (Bad Coverage and Radio Environment)11
3.3 Equipment Fault (UE)12
3.3.1 Security and Authentication Mode Failure12
3.3.2 UE Freeze13
3.4 Not Radio14
3.4.1 Disconnect on RAB Setup14
3.4.2 Resources Unavailable (Congestion)15
3.4.3 UE Sensitivity Fault16
3.5 Abnormal blocked calls17
3.5.1 Unclassified - Unanswered RRC requests17
3.5.2 Faulty Block Recording - Barred Network18
3.5.3 Call Initialisation during L.U. signalling19

1 Introduction
This document describes some of the typical dropped/blocked call classifications encountered during several RAN Tuning Projects for WCDMA networks. The purpose of the document is for RAN Consultants to understand some of the problems to make the UE analysis and classification easier. The analysis has been based on limited data (for example no UETR data or data based on similar tool, no usage of RBS and RNC tracers) and for this result there could be a deviation in the results. Some of these classifications are only a guideline and should be viewed merely as documenting the typical problem until the correct reason behind the dropped call is established. All these dropped/blocked calls categories are adapted to the radio environment evaluation thresholds set up for the MTN 3G RAN Tuning project in the post-processing tool TEMS Deskcat 5.6. In the table below are listed the main causes that must be considered during the analysis, with the explanation for each cause.

CLASSIFICATION CRITERIA

Poor Coverage
The Drop occurs in regions where conditions CPICH RSCP and/or CPICH Ec/No are measured in critical values not suitable for a proper connection. Bad Radio Environment
Every drop that occurs when Best Server is Missing (Mostly in good CPICH RSCP conditions). The UE active set update cannot follow the quick coverage changes. In this case Pilot Pollution situations are included as well (3 cells in AS and more than 1 strong SCs is interfering the connection within a range of 5 dB - Ec/No basis evaluation). Congestion

Every drop that occurs when there are no more available radio resources for the connection. The network sends an RRC Connection Release when the RBS reaches the maximum available Power in DL. Not Radio

Every drop that occurs when the radio conditions are good, the logging equipment is working properly and the RRC connection release cause (marked usually as "Unspecified") could be attributed to a RBS/Network fault, (including UL UE power going to maximum even if the CPICH RSCP is measured at good values, crossed feeders causing false missing neighbours, crossed UL-DL feeders, wrong parameter settings that can affect accessibility/SHOs in the cell). Equipment Fault

Every drop that occurs when TEMS Investigation/UE are Blocking or Freezing and/or SW is crashing, so that it's not possible to maintain the connection. Missing Neighbours
Every drop that occurs when there are poor RSCP and/or Ec/No levels/quality on the Best Server/AS, with the contemporary possibility for the UE to perform a SHO on a better cell that is not declared as a Neighbour for the AS cells themselves.

2 Dropped Calls Classification
The main cases and dropped call causes are listed below.
2.1 Missing Neighbours
Every drop that occurs when there are poor RSCP and/or Ec/No levels/quality on the Best Server/AS, with the contemporary possibility for the UE to perform a SHO on a better cell that is not declared as a Neighbour for the AS cells themselves. An example of dropped call for missing neighbour problem is shown in figure below.

Problem Description: The Active Set best server is cell 61888 (SC = 205). During the...
Continue Reading

Please join StudyMode to read the full document

You May Also Find These Documents Helpful

  • An Inspector Calls Essay
  • Specifications Essay
  • Essay about One night @ Call Centre
  • Job Specification Essay
  • Essay about Design Specification
  • Assignment Specification Research Paper
  • Quantity and Specifications Essay
  • DATABASE SPECIFICATIONS Essay

Become a StudyMode Member

Sign Up - It's Free