Research On Terrestrial Multimedia Broadcast Positioning Technology Based On CMMB

China Mobile Multimedia Broadcasting (CMMB), which is an independently researchedand developed digital multimedia broadcasting technology, is widely used for its advantagessuch as the high data transfer rate, the strong anti interference ability and the wide coveragerange. Many domestic research institutions focus on research on mobile location technology byCMMB signal. The CMMB signal system is transformed for a little to achieve precise navigationand positioning in the city, and the transformation takes advantage of the characteristic of hightransfer rate, strong anti interference ability of Orthogonal Frequency Division Multiplexing(OFDM) technology on the based of the terrestrial CMMB technology and without affecting theCMMB multimedia broadcasting. The pioneering research on the technology offers a new ideaof development of the navigation and positioning technology, and achieves the organic fusion ofterrestrial multimedia broadcasting technology and navigation and positioning technology. Theapplication of this technology will be of actual significance for Positioning, Navigation andTiming (PNT) service especially urban vehicle navigation, location based service and tourismconsulting service.The key technical research of accurate navigation and positioning in cities by the use ofterrestrial multimedia broadcast signals are carried out and the test platform of positioningsystem is designed and realized in this paper on the basis of an in depth analysis of the CMMBsignal system. This paper makes the accurate navigation and positioning of cities in the use ofthe existing CMMB network as a starting point, seeking a locating method under the premise ofnot affecting the receiving performance of the existing Single Frequency Network (SFN) as aresearch point, and realizing the precise position of the multimedia broadcast positioning systemas the ultimate goal. The transmitter system structure, design of signal system, receiversynchronization technique and multiple access pseudo range measurement method based onterrestrial multimedia broadcast positioning system are mainly studied in this paper. The researchmainly solves the problem of multiple access pseudo range measurement and receiversynchronization in SFN based on OFDM modulation technology by means of theoreticalanalysis, algorithm research, simulating identification. The paper carried on innovatively theresearch of accurate navigation and positioning of cities by the use of multimedia broadcastsignals. The main research work in this paper is as follows:(1) On the basis of further study of CMMB signal system and OFDM key technologies, thenecessary conditions and key elements of urban navigation and positioning are summarized. Thesystem structure of using the ground multimedia broadcast signals to realize accurate positioningis designed and the influencing factors and general solutions of precise position are analyzed. Subsequently, the channel estimate and proportion technology are dicussed.(2) The key technologies of the transmitter system in the terrestrial multimedia broadcastpositioning system are researched deeply. The research started with the time synchronizationbetween the base stations, designed the signal system of the position system and established allthe transmitter system parameters such as the modulator design and the power budget. Theresearch focuses on the signal structure design, time synchronization among the station, thetransmitter power and positioning precision estimaion.(3) Further research on the multi access pseudo range positioning measurement of terrestrialmultimedia broadcast signal has been done. Aiming at the position shortcomings of the CMMBsignal, a multiple access pseudo range measurement technology based on ZC sequence ofOFDM modulation is proposed innovatively through the comprehensive comparison withmultiple design schemes. The ranging signal design is optimized and its performance is analyzedthrough the further study of ZC sequence. The transmission performance of the ranging signal inthe multiple access interference channel, multi path fading channel and white Gaussian noisechannel are researched by the simulation and a signal capture method to improve theperformance is proposed. Furthermore, the digital delay locked loop (DLL) technology isapplied to the track of the ranging signal for the first time to realize the multi access pseudorange measurement for the multimedia broadcast positioning signals by the simulation.Thesimulation shows that the pseudo range measurement accuracy can reach one meter.(4) Further research on the synchronization technology, especially the frequency offsetestimation technology has been done. The fractional frequency offset estimation and integralfrequency offset estimation methods for the training sequence of ground multimedia broadcastsignal are simulated and verified. What’s more, these methods are applied to the complexfrequency offset estimation of multimedia broadcast positioning system under the condition ofthe static state. Afterward the proposed algorithm validity when applied to the complexfrequency offset estimation and the performance resist to Gaussian white noise was simulatedand verified. The simulation result shows that frequency offset estimation error is close to or lessthan one percent of the subcarrier spacing when SNR is bigger than zero, and the greater thesignal to noise ratio, the smaller the frequency estimation error.(5) The overall architecture of the receiver is designed simply and main features of all thefunction modules, the pseudo range measurement methods, demodulation method of positioningmessages and position calculation method are researched. Finally, the design of receiverhardware platform is introduced simply.