A novel adaptive Wireless-Fidelity (Wi-Fi) system is the combination of radio frequency identification (RFID) technology, programmable intelligent microcontroller development board (PIDB) and reconfigurable antenna with beam shape characteristics. The system is capable to sustain a Wi-Fi signal adaptively above its threshold level (-81 dBm) within a range up to 100 m across three different buildings with variety indoor environments and floors. It is found that the modified ground reflection model has successfully predicted the total path loss of the test-bay buildings which consist of corridors, several floors and windows. The modified propagation model is extremely crucial in determining the projection and height of reconfigurable antenna to efficiently cover the scattered measurement points across the three buildings. The need of comparable signal strength is compulsory since the signal strength between 2.4 GHz of reconfigurable beam shape antenna and 0.433 GHz of RFID tag is different within the same distance. When reconfigurable beam shape antenna radiates with a minimum gain of 4.85 dBi, the measured signal strength shows that most of the measurement points are below Wi-Fi‟s threshold level which is from -69.001 dBm to -115.4530 dBm. However, the proposed system is able to boost all the signal strength above the threshold level with three different gain of reconfigurable beam shape antenna, 7.2 dBi, 9.9 dBi and 14.64 dBi through the activation of mobile RFID tag at different measurement points at one time. The boosted signal strengths are within the range of -69 dBm to -73.056 dBm. The capability of the mobile RFID tag in producing certain level of signal strength has been successfully exploited as a wireless stimulator for the system to adaptively activate certain PIN diode switches of reconfigurable beam shape antenna in this finding. The proposed system also has a great potential in realizing a new smart antenna system replacing the conventional switching beam array (SBA) antenna.
2. Yarkony, N. and N. Blaunstein, "Prediction of propagation characteristics in indoor radio communication environments," Progress In Electromagnetics Research, Vol. 59, 151-174, 2006.
3. Phaiboon, S. and P. Phokharatkul, "Path loss prediction for low-rise buildings with image classification on 2-D aerial photographs," Progress In Electromagnetics Research, Vol. 95, 135-152, 2009.
4. Rappaport, T. S., Wireless Communications: Principles and Practice, Prentice Hall, Dec. 2001.
5. Liechty, L. C., E. Reifsnider, and G. Durgin, "Developing the best 2.4 GHz propagation model from active network measurements," IEEE 66th Vehicular Technology Conference, 894-896, 2007.
6. TheoFIlogiannakos, G. K., T. V. Yioultsis, and T. D. Xenos, "Experimental validation of a hybrid wide-angle parabolic equation --- Integral equation technique for modeling wave propagation in indoor wireless communications," Progress In Electromagnetics Research, Vol. 82, 333-350, 2008.
7. Yang, F. and Y. Rahmat-Samii, "Reflection phase characterizations of the EBG ground plane for low profile wire antenna applications," IEEE Transactions on Antennas and Propagation, Vol. 51, No. 10, 2691-2703, 2003.
8. Promwong, S., P. Supanakoon, and J.-I. Takada, "Ground reflection transmission loss evaluation scheme for ultrawideband impulse radio," Ecti Transactions on Electrical Eng., Electronics, and Communications, Vol. 5, No. 1, 2007.
9. Dwivedi, V. K., A. Gupta, R. Kumar, and G. Singh, "Performance analysis of coded OFDM system using various coding schemes," PIERS Proceedings, 1249-1253, Moscow, Russia, 2009.
10. Choi, S. W., W. R. Oh, and H. J. Hong, "Method for calculating interference protection ratio of atsc system from mobile WiMAX system," PIERS Proceedings, 619-623, Moscow, Russia, 2009.
11. Prieto, J. B., P. F. Reguero, R. M. L. Toledo, E. J. Abril, S. M. Franco, A. B. Martinez, and D. Bullid, "A model for transition between outdoor and indoor propagation," Progress In Electromagnetics Research, Vol. 85, 147-167, 2008.
12. Hodgkinson, T. G., "Wireless communications --- The fundamentals," BT Technology Journal Springer, 11-26, 2007.
13. Zaggoulos, G. and A. Nix, "WLAN/WDS performance using directive antennas in highly mobile scenarios: Experimental results," Wireless Communications and Mobile Computing Conference, IWCMC, 700-705, 2008.
14. Kotz, D., C. Newport, R. S. Gray, J. Liu, Y. Yuan, and C. Elliott, "Experimental evaluation of wireless simulation assumptions,", Technical Report TR2004-507, Department of Computer Science, Dartmouth College, 2004.
15. Tayebi, A., J. Gomez, F. Saez de Adana, and O. Gutierrez, "The application of ray-tracing to mobile localization using the direction of arrival and received signal strength in multipath indoor environments," Progress In Electromagnetics Research, Vol. 91, 1-15, 2009.
16. Seow, C. K. and S. Y. Tan, "Localization of omni-directional mobile Device in multipath environments," Progress In Electromagnetics Research, Vol. 85, 323-348, 2008.
17. Abdolee, R., W.-P. Zhu, and M. Sawan, "Digital beam-forming implementation for downlink smart antenna system," 52nd IEEE International Midwest Symposium on Circuits and Systems, 615-619, 2009.
18. Helhel, S., Ş. Özen, and H. Göksu, "Investigation of GSM signal variation dry and wet earth effects," Progress In Electromagnetics Research B, Vol. 1, 147-157, 2008.
19. Wu, R.-H., Y.-H. Lee, H.-W. Tseng, Y.-G. Jan, and M.-H. Chuang, "Study of characteristics of RSSI signal," IEEE International Conference on Industrial Technology (IEEE ICIT), 1-3, 2008.
20. Nafarieh, A. and J. Ilow, "A testbed for localizing wireless LAN devices using received signal strength," IEEE Communication Networks and Services Research Conference, 481-487, 2008.
21. Bouchereau, F. and D. Brady, "Bounds on range-resolution degradation using RSSI measurements," IEEE International Conference on Communications, Vol. 6, 3246-3250, 2004.
22. Ridgers, T. J., C. Boucey, J.-P. Frambach, L. R. du Roscoat, and P. Gamand, "Challenges in integrating embedded RF within a SOC," IEEE Radio and Wireless Symposium (RWS), 547-550, 2008.