Channel Protection And Anti-Jamming Technique For Medical Image Transmission Over Wireless Channel

Telemedicine is the use of modern telecommunication technologies and computer multimedia technologies for the provision of clinical care to individuals at a distance. It already plays a key role in medical field, is widely applied in cardiopathy, actiontherapy, dermatotherapy etc. Wireless telemedicine overcomes the limitation of wire mode that should be equipped with wire devices, it can be used in special fields, for instance disease areas, remote areas, mobile objects such as plane, boat and battleground, ambulance, and real-time health monitoring etc. Medical image, one of important information in telemedicine system, is focused on how to transmit, however, reliability of transmission is always lacked. With the development of wireless telemedicine, transmitting high quality image will be an important task, it is worth of research in medical and communication field.A new approach combining wavelet-based Vector Quantization(VQ) compression coding with concatenated coding, spread spectrum modulation and anti-jamming technology is proposed to mitigate effect of fading channel and interference for the medical image transmission. Based on human vision, VQ coding and unequal error protection concatenated coding are integrated to correct transmission errors; and multi-channel spread spectrum modulation is used to mitigate the distortion caused by fading channel; anti-jamming technique further improves the performance of suppressing interference.Firstly, reasonable strategy for wavelet-based VQ coding, unequal error protection concatenated coding and spread spectrum sharing limited channel resource is developed. The improvement of three factors for medical image transmission over fading channel is analyzed. Lowest frequency wavelet subimage can share more channel resource with low compression rate and strong correct capability, on the other hand, high frequency subimages are performed VQ coding with high compression rate, channel coding with weak correct capability, satisfying image can be obtained. Spread Spectrum can improve fading channel, however, Concerning about transmission efficiency, it is not reasonable to use spread spectrum with highgain.Weight feedback adaptive canceller is adopted for high power multi-narrowband interference in frequency-domain. After analyzing the limitation of slow convergence in adaptive Least Mean Square(LMS) algorithm, it is brought forward the method of transforming signal into frequency domain, taking advantage of the orthogonality of discrete Fourier transform, the adaptive LMS filter is performed for each frequency element in transform domain. The convergence of algorithm is decided by the power of each frequency element and step, not limited by the number and power of interference. Weight feedback can real-timely modify the step, fasten the speed of convergence, and improve the performance of system.Finally, a new rejection method for time-varying narrowband interference (TVNBI) is presented, that is based on adaptive wavelet packet transform with time decomposition. Received signal is firstly decomposed into small intervals, it is performed wavelet packet decomposition in each interval, Then, according to the distribution characteristics of power spectrum density, TVNBI is exactly and quickly located in proper frequency belt. By setting TVNBI to zero, the useful spreading signal can be restored by wavelet packet synthesis...