Image transmission on MC-CDMA system over Rayleigh and AWGN channel using OVSF spreading code

Data transmission via wireless communication system is not only in text form but it also can be in image form. In the process of sending data or information, it often experiences interference in transmission media, which is fading. The method used in this research is by simulation using MATLAB. The simulation of CDMA-MIMO (STBC) system with Walsh spreading code is expected to reduce the disturbance of fading. Fading channels can be modeled using Rayleigh distribution. The number of users and spreading factors affect the performance of CDMA-MIMO (STBC) systems. The parameters used in this simulation were SNR, BER, and PSNR. The results showed that image reconstruction passing CDMAMIMO system with spreading factor 4 has better image quality. Its PSNR 33.9589dB when SNR -10dB. SNR was increased 10 dB then PSNR 60.00 dB. The increasing of spreading factor to 8 and 16 was obtained by increasing PSNR, PSNR 35.0685 dB and PSNR 37.5665 dB, respectively. For 4 users with Spreading Factor 4 and SNR 0 to 5 dB, it was changed the BER. This is influenced by changes in SNR. The higher SNR value, the average value of BER will be smaller. A growing number of users from 1 to 4 users were decreased the performance of the MIMO CDMA system when observed from the BER and PSNR.

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IMAGE TRANSMISSION THROUGH MC-CDMA CHANNEL: AN IMAGE QUALITY EVALUATION

International Journal of Wavelets Multiresolution and Information Processing ◽

10.1142/s0219691308002707 ◽

2008 ◽

Vol 06 (06) ◽

pp. 827-850 ◽

Cited By ~ 5

Author(s):

TICK HUI OH ◽

KIM GEOK TAN

Keyword(s):

Image Compression ◽

Time Domain ◽

Image Transmission ◽

Orthogonality Condition ◽

Frequency Separation ◽

Cdma System ◽

Spreading Code ◽

Frequency Diversity ◽

Cdma Systems ◽

Code Division Multiple

The multicarrier code division multiple access (MC-CDMA) system is considered as an advancement in mobile communication system. Seen as the next generation communication technology after the 3G, signals can be easily transmitted and received using the Fast Fourier Transform (FFT) device without increasing the transmitter and receiver complexities. Besides, the MC-CDMA system provides good spectral efficiency. If the number of sub-carriers and the spacing between sub-carriers are chosen properly, it is unlikely that all the sub-carriers will be in deep fade. Thus, it provides frequency diversity. Frequency diversity means that frequencies separated by more than the coherence bandwidth of the channel will be uncorrelated and thus will not experience the same fades. Three types of MC-CDMA systems were proposed — MC-CDMA, multicarrier DS-CDMA and multitone CDMA. In MC-CDMA systems, the transmitter spreads the user data over different sub-carriers using spreading code (Hadamard Walsh code) in frequency domain. The multicarrier DS-CDMA system spreads the S/P converted data streams using spreading code in time domain. This scheme is proposed for uplink communication because this scheme can provide quasi-synchronization. In the MT-CDMA scheme, the S/P converted data stream is spread in time domain so that the spectrum of each sub-carrier prior to spreading operation can satisfy the orthogonality condition with minimum frequency separation. Thus, the spectrum of each sub-carrier no longer satisfies the orthogonality condition. MC-CDMA uses longer spreading code as compared to other schemes and thus accommodates more users. The JPEG2000 still image compression is a new image compression technique which is optimized not only for efficiency, but also for scalability and interoperability in network and mobile environment. This standard can provide superior low bit rate performance and continuous-tone and bi-level compression. Because of the robustness to bit errors, JPEG2000 is widely used in wireless communication channel.

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