Siting Mobile Phone Base Stations a GRASS application on location selection WANG, Wen-Chieh (Jeffrey) HSU, Chien-Liang Chaoyang University of Technology

GRASS: Siting Mobile Phone Base Stations Outline Introduction Basic Concepts Implementation Verification Conclusion 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

GRASS: Siting Mobile Phone Base Stations 1. Introduction 1.1 Background 1.2 Objectives 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

GRASS: Siting Mobile Phone Base Stations 1.1 Background Quality of service vs. health concerns Siting mobile phone base stations is often a fierce issue in Taiwan, because: Densely populated urbanized areas occupied by high-rise buildings The NIMBY-ism and unfair compensation Intense competition, secrecy, and under the counter deals 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

GRASS: Siting Mobile Phone Base Stations 1.2 Objectives Create a freely available solution to foster the knowledge dissemination and open discussion of siting mobile phone base stations. Serve as an experiment to learn and test GRASS’s LOS and other raster processing capabilities 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

GRASS: Siting Mobile Phone Base Stations 2. Basic Concepts 2.1 Mobile phone system 2.2 Base station characteristics 2.3 Assumptions 2.4 Rationale of the solution 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

GRASS: Siting Mobile Phone Base Stations 2.1 Mobile Phone System MS BS MTX [Courtesy of Wikipedia] 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

2.2 Base Station Characteristics On the supply side Signal strength Channel capacity On the demand side Terrain Spatial distribution of mobile stations [Courtesy of Wikipedia] 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

GRASS: Siting Mobile Phone Base Stations 2.3 Assumptions Mobile phone system’s radio signal behaves like light Only works on the “macro” type of cell There are four different cell sizes in a GSM network - macro, micro, pico and umbrella cells. 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

2.4 Rationale of the Solution From a “worm’s eye view’: Only those BS a MS can see can serve it. Only those BS within service distance is qualified. Closer BS, i.e. stronger signal, is preferred. Preferred BS must still have capacity to serve. Go through every possible combination to find the optimal set of BS. 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

GRASS: Siting Mobile Phone Base Stations 3. Implementation 3.1 Some compromises 3.2 The algorithm 3.3 The code structures 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

GRASS: Siting Mobile Phone Base Stations 3.1 Some Compromises A deterministic approach to a stochastic process Use readily available UNIX tools instead of low-level programming Raster-based GIS tools and execution speed limit the precision 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

GRASS: Siting Mobile Phone Base Stations 3.2 The Algorithm (1) Prepare the DTM and MS distribution map. Create a BS’s distance map. Block those distances over limit to create the availability mask. Create the BS’s visibility map through line-of-sight (LOS) analysis. Remove “invisible” areas from the availability mask. Save the availability mask for later use. Assign MS demands to it, from near to far, until reaching its capacity. 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

GRASS: Siting Mobile Phone Base Stations 3.2 The Algorithm (2) Repeat step 2 through 7 for every other BS. Select a set of BS and create the set’s assignment map. Prepare each BS’s distance map so that those unavailable areas have extremely high value. Identify each cell’s closest BS and record that BS in the assignment map. Repeat step 9 through 12 for every possible BS set. Examine and compare all sets’ result to find the optimal combination of BS. 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

3.3.1 Code Listing of bs.test.sh #!/bin/sh if test "$GISBASE" = ""; then echo "You must be in GRASS to run this program." exit fi bs.dist.sh 1 125 1425 bs.dist.sh 2 525 1825 bs.dist.sh 3 575 2175 bs.dist.sh 4 525 2175 bs.dist.sh 5 675 2525 bs.dist.sh 6 625 2725 bs.dist.sh 7 675 2775 bs.dist.sh 8 1275 3425 bs.dist.sh 9 2275 3425 bs.dist.sh 10 2675 3475 bs.dist.sh 11 2225 3075 bs.dist.sh 12 2525 2275 bs.site.sh 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

3.3.2 Code Structure of bs.dist.sh 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

3.3.3 Code Structure of bs.site.sh 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

GRASS: Siting Mobile Phone Base Stations 4. Verification 4.1 The site 4.2 Results 4.3 Discussion 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

GRASS: Siting Mobile Phone Base Stations 4.1 The Site (1) 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

GRASS: Siting Mobile Phone Base Stations 4.1 The Site (2) 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

GRASS: Siting Mobile Phone Base Stations 4.2 Results (1) bs.dist.sh result for BS3 bs.dist.sh result for BS4 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

GRASS: Siting Mobile Phone Base Stations 4.2 Results (2) bs.dist.sh result for BS5 bs.site.sh result 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

GRASS: Siting Mobile Phone Base Stations 4.3 Discussion 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

GRASS: Siting Mobile Phone Base Stations 5. Conclusion 5.1 Summary 5.2 Further work 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

GRASS: Siting Mobile Phone Base Stations 5.1 Summary The BS siting problem is one type of the broader location-allocation problems. The LOS-based GRASS application does provide an intuitive approach to the BS siting problem. The current bottleneck of obtaining a solution is not at the LOS computation but at the assignment of BS capacities to MS demands from near to far. 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

GRASS: Siting Mobile Phone Base Stations 5.2 Further Work Short-term: Improve the robustness of the code so that under no circumstance will there be unused BS capacities. Revise the code to provide more automation and execution efficiency. Long-term: Use a stochastic simulation instead of the deterministic heuristic to reflect the true nature of people making phone calls. Replace the simple LOS analysis with a more realistic method to model the behavior of mobile phone radio signal. 09/14 FOSS4G2006 GRASS: Siting Mobile Phone Base Stations

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