What are the challenges for RSSI based location systems?
A. The common challenges are: • Wrong channel problem (WCP)—When the AP is on a particular channel it is possibly able to receive packets transmitted from adjacent channels albeit at a lower received power. Thus the AP then reports the packet with lower RSSI value, which would cause the location of the client to be estimated further than actual in the location server. This is observed in 2.4 GHz band due to AP filter limitations and 802.11b modulation techniques, even for 802.11g/n clients, as they use 802.11b for probe requests. S60 client driver can eliminate such problems. • Antenna diversity issues (ADI)—It was also observed that the same packet was received on the 2 AP antennas at considerably different power. This can be due to challenges of gathering reliable RSSIs with antenna diversity. The AP must listen on one antenna during start of packet then switch to a different antenna during packet reception in order to get better reception, all within a few micro seconds. • Client co
