Some Urban District TD-SCDMA Wireless Network Planning Design Proposal

TD-SCDMA has the proprietary intellectual property rights international correspondence standard as our country first, has the frequency spectrum efficiency to be high, can realize global roaming, is suitable for the network planning and the optimization, suits each kind symmetrical and the asymmetrical service, the fishing net and the terminal performance-to-price ratio high this 4 greatly prominent superiority. The TD-SCDMA standard usedTime division duplex,Intelligent examination,Union examination,Upward synchronization,Relay cut,Dynamic channel assignment,upshshifting and so on many key technologies, have the unique merit in the wireless network planning and the optimized aspect。The tetherless access network's grade of service and the base depot distribution, equipment's disposition has the close relationship. In the network design, should act according to the different service area the economic development situation, the trade development importance and the network development phase, defines the different network grade of service standard, achieves the good investment effect. The wireless network planning goal manifests specifically in the cover, the capacity, the quality and the cost 4 aspects.The 3G antenna cover request may use the service type, covers the region and the cover probability target attributes. Regarding newly built network, so long as had determined the cover goal, may Large expanse of establish the stand in the entire coverage area, because on the other hand does not have the present net experience and the correlation data uses for reference, lacks the TD local fishing net experience, the network planning can only rely on the theory and the experiment network test result, the wireless network planning accuracy is relatively bad.The designers should act according to the link budget theoretically definite plot radius, what usually use is the COST231-Hata formula takes the urban district environment path loss model. The link budget can instruct to plan the plot radius establishment and the station site distribution, under the different environment the link budget method is completely consistent, only will be the link budget parameter will have certain difference, should act according to the different environment selection appropriate link budget parameter. The commonly used method is tests through Che Zai, obtains the local path loss test data, then through plans with the method, item and the terrain feature factor carries on the adjustment with these data to primitive dissemination model formula's each coefficient, after causing the adjustment, the formula predicted value and the measured data error are smallest. Thus, the process will adjust the later dissemination model path loss forecast the accuracy to enhance greatly, can compare reflects the local wireless dissemination environment well the characteristic. The vehicle carries the test model to have 2 kinds, one kind is the CW test, another kind of test is the present net test, may provide the accurate forecast based on the CW test's dissemination model adjustment result for the network planning, in XX city network design is through the CW test, obtains in the path loss data correction original dissemination model according to the data processing the function coefficient, causes the model the test value and the true error is smallest.The 3G service already includes the present GSM/GPRS on-line existing voice feature, the data traffic as well as other value-added service, also includes the 3G network unique new service, like videophone, class media service and so on. Through counts the establishment service model to the user use service intensity, including service type, service characteristic parameter, service load bearing and service quality objectives 4 aspects. The telephone traffic model is the network planning foundation, model standard the immediate influence to the entire network plan effect. Regardless of being the electric circuit territory or groups the territory, 2G and in the 3G telephone traffic model's establishment and the computation, the principle is the same, the 3G telephone traffic model knowledge has made some supplements according to the 2G service characteristic, therefore the 2G telephone traffic distribution characteristic may take forecasts the 3G telephone traffic distributed basis. Someone in the city plan the dutyfactor is 0.1 service: The WAP browsing, the electronic transaction, the WWW service equivalent is WWW the service model, the dutyfactor is 0.6 above service: The downloading class service, the low-speed data service, EMAIL, the photography picture carries on the transmission, the video frequency fragment transmission, the position/guidance/information service equivalent is the EMAIL service model, establishes the equivalent service distribution model then to estimate the capacity. After the service model analysis method has the Equivalent Erlang, Post Erlang-B, Campbell, Stochastic knapsack 4 kinds.After the link budget determined approximately satisfies the cover goal to need the base depot quantity, simultaneously after the capacity estimate, obtains in satisfies the base depot quantity which the capacity goal under the premise needs, compared with the satisfied cover demand and capacity demand base depot quantity, choice big takes the preliminary cloth station quantity. And passes the over-carriage site selection, definite base depot geographical position. According to the cover, the capacity, the quality requirement and the installed capacity determine each base depot the hardware and the software disposition, including sector, carrier and channel unit quantity.At present the commercial TD-SCDMA simulation software is realizes according to the static simulation principle. Carries on the system simulation on the computer using the planning software, may analyze the network under the different system parameters and the establishment network performance, determines the appropriate network design variable and the plan. The simulation uses the Datang mobile communication equipment Limited company independent development to aim at the TD-SCDMA system's wireless network planning software specially.Compared with other communications system's planning software, increased the smart antenna wave velocity size enlargement, UE links and so on direction of arrival estimate, dynamic channel assignment, time slot disposition. Under the guarantee network simulation condition and the process correct reasonable premise, then needs the question which appears to the network simulation result to carry on the judgment, discovers the base depot establishment the unreasonable factor, and makes the adjustment to it.Regarding TD-SCDMA, the different frequency indirect strength cut is indirect the strength cut performance the frequency to be more superior than, therefore looked from the network quality angle, should first use the different frequency network. TD-SCDMA is more suitable than other any kind of 3G network to use the indoor outside different frequency network way.Someone the city network planning is precisely carries on the plan based on the above basic idea, in the cover, the capacity, the quality, will invest four between discover the best combining site to construct by the reasonable investment have met in the near future and the forward service demand and achieve certain grade of service the mobile communication network. Along with mobile service's unceasing development, the wireless network needs to meet this kind of growth need through the dilatancy. TD-SCDMA has many kinds of dilatancy ways, including increases the power on the original base depot, to increase the new sector and the new carrier. Although adds the new base depot to be possible to solve the capacity problem to a great extent, but considered the new station construction cost and to the peripheral base depot's influence, selects time this method needs to give careful consideration.