A Method Of Solution To WCDMA Pilot Pollution Research

WCDMA is a main technology in the third generation mobile communication system(3G), it will provide more high bandwidth and larger system capacity than the GSM andnarrowband CDMA system, Advanced technology features of this technique and rich andcolorful business types can meet the demand of users of broadband data anytime andanywhere. The WCDMA network has been widely used in many countries, in our countryhas also set up many of the test network. Upon completion of the theory of WCDMAnetwork planning and the actual meshing, communications operators how to build aWCDMA network economy effectively, To maximize the network construction costperformance, these are the most issue of concern, The network optimization has become animportant means to improve network performance.With the rapid development of the construction of3G network construction, number ofWCDMA base stations increasing, and the distance of stations more closer, If the wirelessnetwork planning is not good, will cause larger negative impact to the whole system.Because the WCDMA system is a self-disturbing system, increased the new base station toimprove net coverage and absorb the traffic at the same time, also brought the pilot pollution.Therefore, detailed analyses the reason of pilot pollution appeared, master the methods offound pilot pollution and find out corresponding solutions, is the key to improve networkquality, also is an important work of WCDMA network optimization.In this thesis mainly studies the coverage optimization problem of WCDMA, describesthe3G development situation and characteristics of WCDMA and key technologies; analysisof the main points of WCDMA network optimization, including the difference of3G and2Gwireless network optimization, WCDMA network optimization process, content andclassification; discussed WCDMA coverage optimization problems, including weakcoverage problems, over coverage problems, pilot pollution problems, and suggestions forthese problems are put forward: to increase the number of base station site, adjust position,adjusting the transmit power, adjust the height of the wireless angle. Methods to solve theconventional pilot pollution above are on the same frequency point, and different frequencysolution to make full use of the characteristic of WCDMA system with the same frequency,introducing the transponder signal inside the building, to solve the pilot frequency pollutionproblems by pseudo pilot assisted switching mode. And compared conventional ways of the solution of pollution, different frequency plan in fundamentally solve the influence of thepilot frequency pollution phenomenon, at the same time, also presents a new idea to solvethe pilot pollution.Finally, focused on the coverage optimization problem of pilot pollution, set up theWCDMA experimental network in Tiexi district in Shenyang for field test of the pilotcoverage. According to the test results show that in the experimental network RSCP andEc/Io of frequency signals have problems, pilot pollution is serious. Selected differentfrequency switching ways optimization pilot pollution problems, combined with the actualbase station and the surrounding environmental conditions, selectively rectification indoordistribution system, change the same frequency switching current into different frequencyswitching, after network adjustment, the test data show that RSCP and Ec/Io has beensignificantly improved. According to the test and adjustment of the experimental networkcan draw the following conclusions: Firstly, indoor and outdoor adjustment into differentfrequency can effectively solve the problem of the indoor signal leaks to the interference foroutdoor signal, and has certain effect on EC/NO index improvement. Secondly, changingfrequency indoor distribution system after tests showed the business were normal, indoorand outdoor different frequencies switching to normal. Further can effectively control thenumber of base stations of the same frequency in adjacent areas, to reduce the proportion ofsoft handover and the spending of system resources.This paper presents a new method to solve the pilot frequency pollution problem-different frequency switching solutions, not only effectively solve the pilot pollution, butalso reduce the spending of system resources, put forward a new method and solution in theWCDMA wireless network coverage optimization for operators.