Power And Rate Control In CDMA Cellular Mobile Communication Systems

In many applications of digital communication engineering, the bits of the data sequence transmitted do not have equal significance. Some Unequal Error Protection (UEP) coding schemes have been devised. The H. 263 baseline syntax is very vulnerable to channel errors. Through the experiment we have been able to identify the sensitivities of all H. 263 syntactical elements at the transmission rates of 32 and 64kbit/s. From the simulation results, we can conclude that some elements in H. 263 are sensitive, whereas other types are nearly insensitive. The significance ordering is almost independent of the H. 263 source bit rate. So in our scheme, Video data are first partitioned according to their importance at encoder, and then different important data partitions are further encoded with unequal error protection at channel encoder.The main purpose of this paper is to show that once the video source is dependent on the channel characteristics, better performance can be achieved in terms of reconstructed video quality. Our studies consider a fixed overall bit rate transmission of 64kbit/s over prone memoryless binary channels and the source coder is the ITU-T H. 263 video standard. The variable H. 263 source-coding rate adapts to particular channel Bit Error Rate (BER) at any instant of time. Firstly, we investigated the error sensitivities of H. 263 syntactical elements and grouped them into several classes of different significance. By identifying the most sensitive elements, we developed a data grouping technique that by itself exhibits improved error resilience. We repeating the sensitivity experiments for particular data group scheme, as can be observed, the sensitivity of some type of the elements was greatly reduced and some type was nearly unaffected. Secondly, a video data grouping was devise in order to design UEP schemes. The channel codes used in our simulations are Rate Compatible Punctured Convolutional (RCPC) codes, which fit for our needs in allowing several UEP and EEP schemes. We design an Unequal Error Protection (UEP)scheme and compare its performance with an equivalent (same source coding bit rate) Equal Error Protection (EEP) scheme, using RCPC codes of different rates for forward error protection. UEP scheme have resulted in PSNR improvements over 20dB than no protection scheme when BER is higher than 4 X 10-3. Finally, the experimental results show that this proposed coding algorithm is more error robust against the no error protection algorithm under high error wireless channel.