scholarly journals Simulation Performance of CDMA/QA in Mobile Channel

2011 ◽  
Vol 5 (1) ◽  
pp. 14
Author(s):  
Khalid Hamid Bilal Abdalla
Keyword(s):  
Spread Spectrum ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Multipath Fading ◽  
Direct Sequence ◽  
Simulation Performance ◽  
Mobile Channel ◽  
Link Performance ◽  
Multiple Access Schemes ◽  
Code Division Multiple

The aim of this work is to study, analyze and evaluate software the link performance of mobile communication system under the impairment of the multiple access schemes, down-link thermal noise and the multipath fading in the mobile channel. For this purpose, modeling and simulation has been used to study the effects of nonlinearities in mobile channel using spread spectrum for Direct Sequence Code Division Multiple Access, with Quadrature Amplitude Modulation (DS-CDMA/QAM).

Research on Key Technologies in Multi-Robotic Spread Spectrum Communication System

2013 ◽  
Vol 756-759 ◽  
pp. 2401-2405 ◽  
Author(s):  
Yun Hang Zhu ◽  
Qiong Cai ◽  
Xiu Liang Huang
Keyword(s):  
Spread Spectrum ◽  
Communication System ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Rapid Development ◽  
Direct Sequence Spread Spectrum ◽  
Robotic System ◽  
Direct Sequence ◽  
Walsh Code ◽  
Code Division Multiple

It has become a hot research topic that to improve the coordination performance of multi-robotic system by communication. With rapid development of wireless communication and robot technologies, multi-robotic system based on spread-spectrum technology has become product of combining two technologies. Code Division Multiple Access (CDMA) technology is applied in multi-robotic communication system here. According to the modified m-Walsh sequence got by the way of analyzing the relation characteristic of Walsh-code and m-sequence, the best direct sequence spread spectrum (DSSS) PN code and the improved RAKE receiver scheme are proposed, which satisfied the requirements of real-time performance, reliability and confidentiality in multi-robotic communication system, and have great significance for the research of multi-robotic communication system.

scholarly journals FPGA implementation of DS-CDMA Transmitter and Receiver

2018 ◽  
Vol 6 (3) ◽  
pp. 179
Author(s):  
Harinath Mandalapu ◽  
B Murali Krishna
Keyword(s):  
Spread Spectrum ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Original Data ◽  
Direct Sequence Spread Spectrum ◽  
Direct Sequence ◽  
Frequency Channel ◽  
Data Signal ◽  
Code Division Multiple ◽  
Code Division Multiplexing

Direct sequence spread Spectrum (DSSS) is also known as direct sequence code division multiplexing. In direct sequence spread spectrum the stream of information to be transmitted is divided into small pieces each of which is allocated across to a frequency channel across the spectrum. Data signal at the point of transmission is collaborated with a higher data-rate bit sequence (also called chipping code) that divides the data according to a spreading ratio. A redundant chipping code helps the signal resist interference and also enables the original data to be recovered if data bits are damaged during the transmitting. In this project direct sequence spread spectrum principle based code division multiple access (CDMA) transmitter and receiver is implemented on SPARTAN 3E FPGA. The Xilinx synthesis technology (XST) of Xilinx ISE tool used for synthesis of transmitter and receiver on FPGA Spartan 3E.

CDMA Modulation for Communication System Environment using Frequency Hopping Spread Spectrum

2020 ◽  
Vol 6 (1) ◽  
pp. EC-1-EC-13
Author(s):  
Imeldawaty Gultom ◽  
Keyword(s):  
Spread Spectrum ◽  
Communication System ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Channel Model ◽  
Frequency Hopping ◽  
Direct Sequence Spread Spectrum ◽  
Direct Sequence ◽  
Frequency Hopping Spread Spectrum ◽  
Code Division Multiple

In this paper, an overall framework for a joint Special emphasis is placed on the communication segment of the sensing system at 85 GHz. Code division multiplexing using frequency hopping spread spectrum signals is implemented at 85 ghz to take advantage of reduced interference between ambient communication. The framework, which spans the entire chain of signal processing, mat lab is enabled, explained, and simulated using data networking. A template, able to scatter, fraud detection, including radio frequency-block and synchronization non-idealities are built up and analyzed. Also, the implementation of a channel model is into the Win Prop technology and embedded into the simulation of simu link. In the previous paper, they implemented the code division multiple access using a direct sequence spread spectrum at 77ghz for secure communication. Because of using 77ghz for the direct sequence spread spectrum, there will occur noise distortion and interference in the communication system. So that there will be poor system communication between transmitter and receiver. To overcome these problems, our paper explains the implementation of code division multiple access using frequency hopping spread spectrum for better and secure communications. By using this frequency-hopping spread spectrum technology, we can reduce the noise distortion and interference between the transmitter and the receiver. So that our system will be in proper condition to transmit the signals in the same range of frequency without any interference and distortion. FHSS systems can allow a higher aggregate bandwidth for coverage because FHSS provides more channels in the same range of frequencies. In accordance with the bit-error-rate, the module is assessed. By creating white Gaussian additive noise. The attribute is proven to reconcile the theoretical assumptions with the outcomes. By organizing a Rake-Receiver, the system is further boosted with structure configuration without any distortions.

scholarly journals PEMBANGKITAN DATA ACAK TERSEBAR DIRECT SEQUENCE SPREAD SPECTRUM PADA LAJU DATA BERKECEPATAN RENDAH UNTUK APLIKASI TEKNOLOGI CODE DIVISION MULTIPLE ACCESS

SINERGI ◽  
2017 ◽  
Vol 21 (3) ◽  
pp. 187
Author(s):  
Budi Herdiana ◽  
Muhammad Aria ◽  
Jana Utama
Keyword(s):  
Spread Spectrum ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Direct Sequence Spread Spectrum ◽  
Noise Generator ◽  
Direct Sequence ◽  
Pseudo Noise ◽  
Code Division Multiple

Salah satu kelebihan utama sistem komunikasi Spread Spectrum adalah kemampuannya mengirimkan data informasi disertai kode-kode unik sehingga hanya perangkat penerima tertentu saya yang mampu mendeteksinya. Sangat banyak metode pembangkitan kode unik pada spread spectrum ini yang mana salah satunya adalah direct sequence. Penerapan metode ini banyak direalisasikan pada teknologi CDMA dikarenakan kesederhanaan rancangan dan relatif mudah dalam menganalisis karakteristik kerja sistemnya terutama bagian sebaran kode unik pada sebuah lebar pita transmisi radio. Sumber kode unik dalam penelitian ini berasal dari data acak yang dihasilkan oleh pembangkit derau semu atau pseudo noise generator melalui pengaturan panjang kodenya sebesar 16 dengan tingkat kestabilan frekuensi sistem pembangkit kode unik dan frekuensi pembawa masing-masing sebesar 15,020 kHz dan 499,9419 kHz dimana keduanya ini masing-masing menghasilkan nilai persen kesalahannya sebesar 0,0412 % dan 0,000049 % sehingga dampaknya masih cukup baik bagi metode ini apabila diimplementasikan pada teknologi CDMA khususnya diperuntukan untuk laju kecepatan data rendah.  

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