Book: UMTS Performance Measurement: A Practical Guide to KPIs for the UTRAN Environment
Publisher: John Wiley & Sons
Having dealt with in-depth analysis of SS#7, GSM and GPRS networks I started to monitorUTRAN interfaces approximately four years ago. Monitoring interfaces means decodingthe data captured on the links and analysing how the different data segments and messagesare related to each other. In general I wanted to trace all messages belonging to a singlecall to prove if the network elements and protocol entities involved worked fine or if therehad been failures or if any kind of suspicious events had influenced the normal callproceeding or the call’s quality of service. Cases showing normal network behaviour havebeen documented in Kreher and Ruedebusch (UMTS Signaling. John Wiley & Sons, Ltd,2005), which provides examples for technical experts investigating call flows and networkprocedures.While still writing the last paragraphs of UMTS Signaling it became obvious that the focusof leading UMTS technology experts was changing more and more from the investigation offunctional behaviour to the analysis of huge data streams supplied by signalling informationand user data/payload. As a result the idea of a second book was already born before the firstone was ready to be published. Some major customer projects I have been involved inpushed my ideas and knowledge further into this field. Indeed, if one compares radio-relatedinformation in UMTS and GSM radio access network protocols, e.g. the contents ofmeasurement reports sent to the network by mobile stations and base stations, it is obviousthat in UMTS much more radio-specific measurements are executed. Reports are sent morefrequently and by using more sophisticated methods than in GSM to guarantee the quality ofservice in UMTS networks.The radio technology behind UMTS is seen in two different varieties: frequency duplexdivision (FDD, also known as WCDMA), where uplink and downlink data is transmitted ontwo different frequency bands; and time division duplex (TDD), where uplink and downlinkchannels are separated using timeslots. TDD is actually beyond the scope of this book,because it has not been introduced in European and North American networks so far. TheChinese solution of a low chip rate TDD (TD-SCDMA) has not yet been deployed in thefield, and although deployment may start during 2006 it will take a while before performancemeasurement becomes crucial for TD-SCDMA operators. First they have to set emphasis onthe execution of functional tests. Nevertheless, many measurement definitions and keyperformance indicators presented in this book will also be valid in TDD networks apart frommostly radio-related measurements and soft handover analysis, because there is no softhandover in TDD.