8/14/2019 Footprint Part 1 of 6 Introduction

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FootprintChanging the RF cost performance paradigm

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Page 1 - Footprint One

Expanding services and subscriber expectations in modernwireless communication systems demand high levels of reliability, coverage and capacity performance; withoperators having to achieve more from less. At the RF endthis means:

Greater use of the RF spectrum. Improved coverage and capacity. Expanding services. Higher call-hold times. Increased return on investment. Fewer BTS sites. Smaller less conspicuous antenna. Shared RF infrastructure. Lower installation and maintenance budgets. Limited licensed spectrum, and A shrinking skills base in the field.

RF performance is determined by how well the selectionand integration of all components meet these demands.

As RF component manufacturers continue to develop andintroduce technologies that give them a cost performanceedge, their greatest gains continue to come fromadherence to manufacturing systems and processes thatensure they build components right the first time - gainsthat are a direct result of applied manufacturing qualitycontrol (QC).

Figure 1

The various components selected for their performance,reliability and cost, are an integral part of the final RFsystem (RF interconnection Figure 1). Due largely to alimited knowledge of the dynamics effecting RF

performance at the BTS and the availability of suitablefield test equipment, installation teams tend not use acomponent manufacturers level of QC in the field.Todays performance demands are now changing this practice.

Traditionally Return Loss (RL) and Distance to Fault (DTF)measurements (sweeps) are used to determineinfrastructure condition and performance. Although theseare an excellent measure of electrical match in the RF

chain, network engineers can still be left with bafflingperformance issues that result in:

Dropped calls. Reduced coverage and capacity, and Short call-hold times etc.

Symptoms can include: Mysterious receiver desensitization. Abnormal noise rise. Intermittently high receiver noise floor, or Any combination of the above.

These problems are generally due to RF interference inone form or another reaching the receiver, yet the causeis usually obscure and difficult to isolate with traditionalmethods. Often a process of elimination will find a loose orpoor connection, inferior component, faulty earthing,water ingress and so on.

Passive Intermodulation (PIM) is often considered as apossible cause, and then disregarded as network engineers determine frequency products fall outside thereceiver band. In todays dense RF environment thispractice can be misleading.

Interference may be from an external source, or any in-band or out-of-band frequencies mixing across non-linearRF sections (PIM sources) present due to RF infrastructuredeterioration or poor initial construction.

High quality construction significantly reduces receiverinterference and eliminates most diagnostic mysteries.

Absolute confidence in the infrastructure build qualityreduces analytical process effort, down time, and cost torepair.

Footprint is focused on presenting ideas that fine tunethe RF cost performance paradigm at the BTS.

In this series of articles we will introduce using PassiveIntermodulation (PIM) as a primary QC metric, andinvestigate some of the recent advances in technology,relevant work practices and performance measures.

Future topics include: Part 2: Transparent Infrastructure Concepts,

benefits and testing methodologies. Part 3: Working with PIM The RF phenomenon,

causes and prevention.

Part 4: Prospective receiver interference -symptoms, possible causes and cures. Part 5: Case study details, and Part 6: Frequently asked questions and answers

Introduction (Part 1 of 6)Traditional cost performance boundaries continue to be reviewed as wireless network operators compete for loyalty from asophisticated and often fickle customer base. Todays networks must carry more information at lower costs than everbefore. This series of papers focuses on the critical role of RF systems at the BTS in achieving these goals.