Objectives Introduction Planning Steps Other Considerations Customer Requirements Surveys In-Building Coverage RF Propagation Tests
Planning Tool Preparation and Model Calibration Model Calibration
Link Budget and Other Steps Coverage Esstimation Capacity Considerations Fine Tuning
Site Selection
Objectives:
The aims of this section are to enable the student to:
List the various steps involved in the RF Planning process Explain each of the steps of the planning process
State other factors to be considered in the planning process State customer requirements
Explain the use of Drive Tests Explain the use of Planning tools
Describe the customisation of planning models Perform an RF Planning exercise
Introduction
Chapter 1 introduced the planning and optimisation process in general terms. This chapter looks at each step of the process in detail. The planning processes will be referenced to an imaginary city known as ’ Utopia’ .
Planning Steps
The first step is to understand the customer requirements in terms of: Coverage levels
In-building coverage expectations Proposed roll out plans
Start-up number of sites which the operator may have in mind. The next step is to Survey the city of Utopia to understand
Traffic pattern and distribution Probable growth areas
High business areas etc.
Conducting Propagation tests for in-building coverage and on street signal level estimates.
From the survey data the planning tool is set up and run. Then a draft plan is prepared by dividing the city into a number of regions like Busy business area with Excellent outdoor coverage, medium in-building coverage, good in-building coverage etc. For each of these classifications, a simple link budget along with
an appropriate propagation model, the number of sites required per region. The draft plan is then reviewed with the customer and fine tuned.
Planning Steps
1. Understand Customer requirements
Coverage requirements
In-building coverage expectations Initial Roll out plans
Pre determined number of sites ?
2. Survey:
Traffic Distribution and Pattern Growth areas
High density business/residential areas
Propagation tests for in-building coverage estimates and model calibrations.
3. Prepare Planning Tool
Get Digitized maps
Load maps in the Planning tool.
Use survey data and run the programme.
4. Draft Plan:
Divide city in to number of regions- Busy business areas
Areas that need excellent in-building coverage Medium in-building coverage areas
Use appropriate model and link budgets to calculate the number of sites required per region.
5. Fine Tune Plan:
Perform more drive tests, confirm plan predictions. Review plan with customer and fine tune the plan.
Other Considerations
The planning exercise depends on the type of site under consideration- is it a macro site ( large area ) or a mini site? Is it a micro cell or a pico cell? This is to a large extent defined by the traffic growth projections, amount of spectrum available, coverage required at the time of launch and capacity planned for the first 3-5 years of operation. To start with Macro cells may be designed to give maximum coverage with limited number of sites. As the traffic and capacity increase, cells may be split, or new cells may be added to get more focussed coverage. Tall sites are modified by reducing antenna
heights to get better coverage and minimize interferences.
Other Considerations
Site Selection- Cell Types: Macro ( Large Cells) Mini
Micro Pico
Traffic Growth Projections Site Density required Spectrum Availability Coverage needed at launch
Macro Sites to start with: Maximum Coverage Fewer Sites.
Hence lower initial investment. During Growth phase: Split Cells
Add New Cells
Modify “ tall” sites by reducing antenna height.
All this gives increased capacity and better in- building coverage. On going activities:
Optimization techniques Capacity enhancements Frequency Hopping techniques
Customer Requirements
The success of the planning process depends on how well we understand what the customer wants.It would be a good idea to have a questionnair answered by the customer.
Some of the important questions should include precise boundary limits for the network (does the Govt. have any special conditions?), areas in which medium in-building coverage is considered adequate, areas where excellent coverage is needed, what are the potential growth areas, what are the implementation strategies and specific requirements if any.
Is there any limit on the initial investment for the customer?
What is the minimum the customer is willing to support with reference to the competition?
It is important to understand these customer requirements so that the draft plan will be in tune with what the customer wants and fine tuning becomes easier.
Customer Requirements
What are the boundaries for the network?
Are there any special pockets to be covered due to Govt. requirements?
What are the areas in which medium to average in-building coverage is acceptable? What are the areas where excellent in building coverage is needed?
Areas with high growth potential New colonies under development High revenue areas
Shopping malls, office complexes, industrial estates etc. Initial implementation Strategy:
High usage, high revenue users first? High end residential and business areas? Street Coverage first?
Special areas like 5 Star hotels, Commercial buildings with fine in-building coverage?
High way coverage critical? Total coverage on day one?
Number of sites more than the competition? Etc etc. Any budget limitations?
Give an ideal plan to start with. Let the customer cut corners. Not an easy job!!
Surveys
This is basically a scouting exercise. It is better to spend at least a week in each city/locality. It helps in identifying the network requirements for the city/location. Keep an open eye for the major traffic routes, main roads, the general city layout, types of buildings, location of major hotels, shopping centres, airport, railway station, typical consumer behaviour, telephone density, number of restaurants, bars and clubs, parks and open areas, any historical buildings, old buildings, congested localities with narrow streets, any lakes, ‘ nullahs’ ( narrow canals/waterways ) and so on.
In-Building Coverage
Identify different types of buildings in the city, such as hotels, restaurants, commercial buildings, shopping malls residential and so on. Select a few buildings in each type and conduct propagation tests. Receive signal strength is noted at the entrance ( on the road) of the buildings and inside- more importantly in the basement and ground floor.
This is because the in building coverage is usually less only in these areas. As we go higher up in the building, the coverage usually improves.
With reference to the signal strength in the road, the building penetration loss can then be computed. Repeat the process for all buildings and for all categories of buildings. This will give an estimate of building loss for the locality under consideration.
In-Building Coverage _ Classify Buildings – Hotels/Restaurants Commercial Industrial Residential Shopping malls/markets
Propagation tests in a number of buildings in each variety. RF signal on the road Vs. inside building gives building penetration loss.
Repeat tests in as many buildings as possible to get an estimate of building loss for the area.
In-building coverage affected mostly in ground floor/basements.
Typical Values: ( examples only ) Hotels/Restaurants 15 dB Commercial bldgs 20 dB Shopping malls 15 dB Industrial Estates 12-15 dB Residential buildings 15-20 dB Old/Historical buildings 25-30 dB. RF Propagation Tests
RF survey is done by performing drive tests within the proposed cell site area. For a new network, we set up a test transmitter at a chosen point and measure RF signal strengths at various points. In an existing network, the drive test is used to collect data from the network itself.
A typical RF propagation kit is listed in Table 6-1.
Table 6-1 Battery powered