Simulating GPS Network Performance
In this paper, we create a rough simulation model of the current GPS system using the ns-3 network simulator. Because ns-3 currently has no inherent satellite modules, we have created our own basic satellite mobility module and created a scenario using a GPS satellite constellation and receiver line of sight. We investigate the relation between a receiver's position/altitude and its effect on the number of satellites that are visible, the differences in signal power at receiver, and the theoretical bit error rate. Position and altitude have negligible effects on the bit error rate (BER) of the signal. The main parameters affecting the BER of a GPS frame are signal frequency, antenna gain, thermal noise, receiver power, and bit time. The altitude between the two testing receivers has little effect on the BER because the altitude difference of 8km between the peak of Mt. Everest and the SFU ASB is proportionately small compared to the altitude of GPS satellites (20,200km). The simulation showed that it was able to meet the GPS protocol standards; greater than -128.5dBm signal strength and a minimum of 4 satellites in view for positional accuracy.
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Jaskirat Singh Arora 301319559 jsarora@sfu.ca Michael Kim 301340718 makim@sfu.ca Martin Yang 301347120 yangtaey@sfu.ca