Mobile Multimedia Broadcasting Wireless Network Coverage And Design Examplie

With the development of mobile phone communication, a new "mobile phone TV" concept produce. Foreign ISDB-T, DVB-H, MediaFLO,DMB mobile phone television standard gradually mature and put intocommercial operation. As China’s independent research and development, mobile multimedia broadcasting with complete intellectual property (CMMB, China Mobile Multimedia Broadcast) standard was isestablished and devoted to the construction and operation. The CMBB coveres the ground with UHF signal, as a new kind of wireless radio technology, this paper emphasizes on how to carry out the signal coverage,and how to solve some of the problems encountered in coverage.This paper introduces the classification of electromagnetic, wave channelenvironment and loss of signal. The classification of the electromagnetic wave is based on the electromagnetic wave through different paths to reach the end of the differentiated. The classification of the propagation channel is depend on the geographical environment and the mathematical model is calculated by probability model. The loss of signalclassification reflects the characteristics of power loss of electromagnetic waves in different situations. The paper will also introduce OFDM, guard interval, channel coding, synchronization technology, this technology is a key part of CMMB. The above knowledge provides the theoretical basis for wireless covering in CMMB.The wireless coverage of CMMB is the key issue of the research object of this paper. First of all, the paper introduces the CMMB network architecture,explains the signal from the satellite transmission to the ground, and then from the transmitter to the mobile terminal. According to the technical standards and engineering practice experience, it summes up three kinds of coverage of CMMB, which are the single transmitting stations,single frequency network, signal compensating. In view of these three coverage, carries on the analysis from the concept, scope of application,principle, etc.. Single frequency network as a CMMB wireless coverage of important way, this paper also proposes the same frequency interference protectioninterval concept, the characteristic of channel coding in OFDM,it calculates the interval of not more than15.36kilometers between the two transmitter station, Otherwise it will have the same frequency interference.Secondly, based on the two CMMB project I participated in, the wireless coverage related theory and design method are tested. Through the network simulation of Nanchang City, single frequency network is calculated to judge whether the plan is feasible.According to the simulation results, the coverage, interference of the same frequency,time synchronization,frequency synchronization are found effectively and reduced. These problems are put forward with the solutions based on the theoretical knowledge and practical experience. Shanghai Hongqiao hub of West Terminal Building of indoor distribution system includes CMMB, GSM, CDMA, WLAN,WCDMA and other communication signal coverage, The design ideas and methods can be concluded between inductive CMMB and other system, it will also provides the reference for CMMB and other signal in building indoor distribution system in the future.Finally, the paper summarizes the structure and the research object and puts forward the direction and thinking for further research of CMMB wireless coverage.