Research On TS-NMT Application In Trunking Communication

As an advanced dispatching systems,digital trunking communication system has been more and more widely used both at home and abroad. iDEN is one of digital trunking communication systems which are more rapidly developed and typically used. It is based on the time division multiple access(TDMA) and M-16QAM modulation mode, It also can provide six speech signals. However, With the increaseing number of group user in trunking communication system, in the same channel bandwidth,it needs more advanced modulation technology to improve the channel number and band utilization rate.Professor Liang Dequn brought forward the Time-Shift Non-Orthogonal Multi-Carries Modulation (TS-NMT).Its Time-Shift feature breaks the constraints of orthogonality, so that its performances are better than other modulations on transmitting rate,Average Power Ratio (PAPR),Band utilization rate,against Frequency-shift and Multipath fading.so we want to apply it in the trunking communication system.The main work of this paper are as follows:(1) The design of the maximal length linear feedback shift register sequence pilot signal based on TS-NMT in the trunking communication system.First,the maximal length linear feedback shift register sequences are modulated by seven subcarriers, then they can form into a synthesis signal,that is the pilot signal. What’more,comparing with other pilot signals,it can be improved that it has better performances than other pilots in the experiment of the paper, Finally,it can be used to realise channel equalization by the method of the channel estimation.(2) The design of synchronization method based on the barker in the TS-NMT.Synchronization is very important in the trunking system, the barker code has better autocorrelation characteristics than other pseudo random sequence, so it can be used as the synchronization signal.It is formed through modulating of eleven barker codes by sub-carriers.(3) The design of the TS-TDMA and Q-TDMA.In the paper, I have accomplished design of two kinds of frame structures.They are TS-TDMA and Q-TDMA,and I also have given two time slot allocation modes according to the corresponding frame structures, then have done the different simulation experiments under the different time slots.(4) The complishment of TS-NMT modulation systems and M-16QAM modulatio-n systems.The whole experiment includes several parts:pretreatment of modulation, modulati on, synchronization, designing of filters, sending and receiving of data according to the time slot,channel estimation,demodulation,And the designing of the several simulation systems in different time slots,then doing the experiments by contrasting.Through comparing the performances of two systems in different time slots, it has proved that the data transmission rate, bandwidth utilization, transmission efficiency of TS-NMT are superior to M-16QAM under certain conditions, and also has shown that TS-NMT can achieve more speech number than M-16QAM under the same conditions, so it provides the possibilities that TS-NMT can be used in the actual trunking communication system.