Investigation On Small-step Call Admission Control In CDMA System Of Border Region

China has a long state-border and many neighboring countries. In view of the statesecurity and economy, most of countries do not allow to access the neighboring country’spublic mobile system within their boundaries. How to implement the access control in theborder area becomes a significant problem.At Jan2002, China Unicom’s CDMA system is put into commercial use. From1stOct2008, the CDMA system is run by China Telecom. Along with about ten years reformand expansion, the suburbs, rural area coverage level is higher than before, especially theborder area. But the problem of crossing border signal is increasingly apparent. Thefrequency coordinate on border area becomes more and more important.In recent years, the CDMA system of Dandong City, Liaoning province on the borderarea received a high-power interfering signal from Democratic People’s Republic of Korea(DPRK). Above60%sectors of Dandong CDMA system had an average RSSI above-45dBm. The CDMA system of Dandong is nearly crashed, most of the China Telecomcustomers couldn’t use the mobile phone. Many returns were asked, China Telecomsuffered a great loss.The frequency coordinate meeting was hold between The Ministry of industry andinformation technology and frequency manage department of DPRK. The meeting reachedan agreement that China Telecom should perform call access control at the border area,makeing the China Telecom CDMA signal couldn’t be used in the territory of DPRK.The horizontal distance between Dandong, China and Sinuiju DPRK is less than1kilometer. The narrow border area is the downtown area. This area is traffic concentrationarea and the coverage level is high. If we use the traditional optimized methods to controlcrossing signal, for example: reduceing transmitting power, lowering the height of theantenna and so on, the coverage of downtown area of Dandong can’t be ensured. So theinvestigation on Small-step Call Admission Control in CDMA System of Border Region isnecessary.The purpose of this investigation is trying to realize the call access control on theborder area. The result of the investigation will make the signal of the same sector serve theterritory of china and reject the call access from DPRK. The investigation will promote themethods about the border frequency coordination and reduce the fund of network built. Atthe same time the result of this investigation will give reference materials about the border area frequency coordination.