Telecommunications Blog

WiMAX (Worldwide Interoperability for Microwave Access) ( 802.16 - 802.16e ).WIMAX was developed to promote conformance and interoperability of the IEEE 802.16 standard (Wireless MAN).


we will learn how we can planning a wimax network but first we should know some important things .

 
Frequency Planning :

         • The frequency re-use is extremely important in reducing the interference and therefore increasing the capacity
         • Off-the-shelf frequency assignment do not minimize the deployment cost for your system.
         • An optimum frequency assignments can be applied by considering
         • Site locations
         • Power levels
         • User distribution
         • Spectrum availability
         • Geography and building characteristics.


Site Features Optimization

         • Number of antennas
         • Antenna directions
         • Antenna heights
         • Antenna powers
         • Antenna tilts
         • Number of channels
         • Frequency of channels
         • OFDM Parameters
         • Cyclic prefix
         • Number of subchannels
         • Subchannelization rates
         • Available modulations
         • Handover parameters
         • MIMO settings
         • Uplink / Downlink traffic ratios
         • Voice over IP related issues
         • Backhaul planning: fiber, minilink, HDSL…. capacity issues

TOOLS USED FOR RF PLANNING :



Network Planning Tool :

• Planning tool is used to assist engineers in designing and optimizing wireless networks by providing an accurate and reliable prediction of coverage,  doing  frequency planning  automatically,  creating neighbor lists etc.







•  With a database that takes into account data such as terrain, clutter, and  antenna radiation patterns,  as  well  as  an intuitive  graphical interface, the Planning tool gives RF engineers a state-of-the-art tool to:

       – Design wireless networks
       – Plan network expansions
       – Optimize network performance
       – Diagnose system problems
• The major tools available in the market are Planet, Pegasos, Cell Cad.
• Also many vendors have developed Planning tools of their  own like Netplan by Motorola, TEMS by Ericsson and so on.

• Designing a cellular system - particularly one that incorporates both  Macrocellular  and Microcellular  networks  is  a delicate  balancing  exercise.

• The goal  is  to  achieve  optimum  use  of  resources and maximum revenue potential whilst maintaining a high level of system quality.

• Full consideration must also be given to cost and spectrum allocation limitations.

• A properly  planned system  should allow  capacity  to  be added economically when traffic demand increases.

• As every urban environment is different, so is every macrocell and microcell network. Hence informed and accurate planning is essential in order to ensure that the system will provide both the increased capacity and  the  improvement  in network  quality where  required,
especially when deploying Microcellular systems.


• RF planning plays a critical role in the Cellular design process.

• By doing a proper RF Planning by keeping the future growth plan in mind we can reduce a lot of problems that we may encounter in the future and also reduce substantially the cost of optimization.

• On the other hand a poorly planned network not only leads to many Network problems , it also increases the optimization costs and still may not ensure the desired quality.

** Conditions :

• capacity not constant.
• separate analysis for UL/DL.
• joint coverage/capacity analysis.
• HO areas and levels affect directly system capacity.
• basic shared resource is power.

** Objective parameters :


• coverage.
• capacity (blocking).
• good link quality (BER, FER).
• throughput delay, for packet services Methods.
• preplanned during network planning process.
• real time radio resource management.
• real time power control.








Resource reservation for handling expected traffic without congestion.
           – load per cell/sector, handover areas.

Sets allowable “power budget” available for services.
           – load higher than expected.
           – load “badly” distributed.
           – implements statistical multiplexing.

Estimates average power/load, variations of it are taken care in run time by RRM.
           – maximal allowed load versus average load.

Planning methods

•  Preparation phase.
           – Defining coverage and capacity objectives.
           – Selection of network planning strategies.
           – Initial design and operation parameters.

• Initial dimensioning.
           – First and most rapid evaluation of the network elements count and capacity of these elements.
           – Offered traffic estimation.
           – Joint capacity coverage estimation.

• Detailed planning.
           – Detailed coverage capacity estimation.
           – Iterative coverage analysis.
           – Planning for codes and powers.

• Optimisation.
           – Setting the parameters.

• Soft handover.

• Power control.

• Verification of the static simulator with the dynamic simulator.
           – Test of the static simulator with simulator where the users actual movements are modelled.

Planning

     • Planning should meet current standards and demands and also comply with future requirements.
     • Uncertainty of future traffic growth and service needs.
     • High bit rate services require knowledge of coverage and capacity enhancements methods.
     • Real constraints
               – Coexistence and co-operation of 2G and 3G for old operators.
               – Environmental constraints for new operators.
     • Network planning depends not only on the coverage but also on load.

Objectives of Radio network planning

     • Capacity:
               – To support the subscriber traffic with sufficiently low blocking and delay.
     • Coverage:
               – To obtain the ability of the network ensure the availability of the service in the entire service area.
     • Quality:
               – Linking the capacity and the coverage and still provide the required QoS.
     • Costs:
               – To enable an economical network implementation when the service is established and a controlled network expansion during the life cycle of the network.