Loading...
Please wait, while we are loading the content...
Similar Documents
Comparison between Modified Bahl, Cocke, Jelinek,
| Content Provider | Semantic Scholar |
|---|---|
| Author | Zia, Maha George Saleh, Khaleel Abdul Khader |
| Copyright Year | 2012 |
| Abstract | Turbo codes are suitable for deep-space communications, because of the codes astonishing performance at low values of signal to noise ratio (SNR) and their ability to achieve near Shannon limit of channel capacity. In this paper the performance of turbo codes in AWGN channel is evaluated under different conditions and circumstances. The deep-space channel is almost exactly modeled as a memoryless additive white Gaussian noise (AWGN) channel that formed the basis for Shannon’s noisy channel coding theorem. A comparison between the modified BCJR * decoder, which uses modified forward-backward metrics and the Soft Output Viterbi Algorithm (SOVA) decoder, is also presented. Simulation results for the turbo encoder-decoder system show that care must be taken in choosing different parameters that govern the turbo encoderdecoder scheme, also the enhancement is required for low rate (rate 1/4) turbo encoder that uses symmetrical component encoder. Finally, it is suggested to use asymmetrical (two different rates and generator polynomial components encoder connected in parallel) turbo encoder, especially for rate (1/4) turbo encoder in order to improve the bit error rate (BER) performance of low rate symmetrical turbo encoder under extremely noisy conditions. خلا ـ صلا ـــــــ ة ارفشلا دعت ت ةبسنل ةضفخنملا مٌقلا دنع شهدملا تارفشلا ءادا ببسب كلذو دٌعبلا ءاضفلا تلااصتا ًف ةمئلام ةعرسملا ءاضوضلا ىلا ةراشلاا ( SNR ) نوناش دودح نم بارتقلاا ىلع اهتٌلباق اضٌاو (Shannon limit) .ةانقلا ةٌباعٌتسلا ذه ًف ثحبلا ا ءادا داجٌا مت عون نم ةانق ًف ةعرسملا تارفشلا ( AWGN ) ةانق نا. ةفلتخم طورشو فورظ تحت ع اهتلماعم نكمٌ ةدٌعبلا لاصتلاا ل ةانقلا رٌفشتل نوناش ةٌرظنل ساسلاا لكشت ًتلاو ًسواك عون نم ةانق اهنا ى ةٌمزراوخ نٌب ةنراقم مٌدقت اضٌا مت ( BCJR ) ن مدختست ًتلاو ةلدعملا ظ ا ًماملاا باسحلا ما ًه ةٌناثلاو لدعملا ًفلخل ًبرتٌف ةٌمزراوخ ( Viterbi ) .معانلا جرخلا تاذ رفجملا ماظنل ةاكاحملا حئاتن تنٌب ًتلا رصانعلا فلتخم راٌتخا ًف مامتها كانه نوكٌ نا بجٌ هنا عرسملا ةرفجلا حتاف ططخم مكحت رفجملا عرسملا ةرفجلا عنام ، و تارفشملل بولطم زٌزعتلا كلذك ا تاذ هعرسملا لدعمل ضفخنملا ) .(Rate 1/4 تم رٌغ تارفجم ماذختسا حارتقا مت ءاضوضلا ةدٌدش فورظلا ًف ماظنلا تافصاوم نٌسحت لجا نم ارٌخا لثام نم نانثا(ة دودحلا ةددعتملا هدلوملا ةلادلاوزٌمرتلا ةبسن ثٌح نم نٌفلتخم هرفشلا ًحتاف ، )يزاوتلا ىلع نٌطوبرم ، ـل ةصاخو ( Rate 1/4 ) اطخلا لدعم ءادا نٌسحتل ( BER ) .ةدٌدش ةٌئاضوض فورظ تحت ظفخنملا لدعملا تاوذ ةلثامتملا ةرفشلا ًحتافل |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://www.iasj.net/iasj?aId=10247&func=fulltext |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
