Cellular Networks Frequency Planning Practice.pdf
- 1. Cellular Networks Frequency Planning Practice In a nutshell
- 2. ➢ Freq. Planning aims at achieving best freq. re-use strategy, for minimizing Interference and improve the quality of service. It is more common for 2G cellular networks, where we have multiple frequencies per cell. For higher technologies, planning of the PSC (unique 512) and PCI (unique 504) is more crucial, but the principles are similar. ➢ Two approaches: Manual & Automated ✓ Manual: for single cell or a small cluster of cells (eg using Mapinfo, with Google Earth help). Mostly when addressing specific customer complaints or localized site performance issues ✓ Automated: Massive Scale (many cells). Popular Planning SW includes Atoll (Forsk), & ASSET. ➢ Main Inputs and Outputs of Frequency Planning ✓ Inputs: Antenna parameters (location, radiation pattern, height, azimuth); Transmitted power; Intended coverage distance, Terrain (hills, buildings, etc); Clutter (landscape features), Available Frequencies to choose from, and their band characteristics. ✓ Outputs: Interference Matrix based on calculated optimal frequency allocations. A summarized report is generated with key parameters to decide how good or bad the predicted frequencies are wrt the status quo. ➢ For a network built up from a scratch (e.g Safaricom Ethiopia, to be launched this year), initial planning is done using the RF planning tools which only rely on Predictions using propagation models. ➢ For a full-fledged operational network, usually vendor specific tools will be employed for Frequency re-planning: these would factor-in the input from actual measurements from the mobiles. An example is Nokia’s EdenNet tool. Modern in-house tools can be used in open-loop (measure, calculate, show) or closed loop (measure, calculate, implement, repeat) modes.
- 3. ➢MCOM Illustration for Manual / Small Scale Frequency Planning
- 4. Summary output from EdenNet GSM Frequency Optimization (GFO) Module Calculations (Open Loop) Interference Analysis Layer Average Interference (%) Co-channel Interference (%) Adjacent channel Interference (%) Existing 5.98 4.94 1.04 BCCH 4.31 4.16 0.16 TCH 7.4 5.61 1.8 Proposed 3.87 2.62 1.25 BCCH 1.05 0.77 0.28 TCH 6.28 4.2 2.08 Delta -2.11 -2.32 0.21 BCCH -3.27 -3.39 0.12 TCH -1.12 -1.41 0.29
- 5. Vetting the rePlanned Frequencies against neighbor relations frequency hits
- 6. 0 5 10 15 20 25 30 35 40 45 50 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 711 712 713 714 715 716 717 718 719 720 721 999 1000 1001 1002 1003 1004 Count Channels BCCH Frequency Distribution Existing Frequency Distribution Proposed Frequency Distribution
- 7. 0 20 40 60 80 100 120 88 91 94 97 100 103 106 109 112 116 711 714 717 720 723 726 729 732 735 738 741 744 747 750 753 756 759 1006 1009 1012 1015 1018 1021 Count Channels TCH Frequency Distribution Existing Frequency Distribution Proposed Frequency Distribution