As for the received signal for both cdma and ofdm we

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As for the received signal for both CDMA and OFDM, we can conclude that the CDMA system has more fading effects than the OFDM system, causing the BER in CDMA to be higher than that of the OFDM. Even with the use of Cyclic Redundancy Check (CRC) code generator in CDMA, the BER is still higher for CDMA than it is for OFDM. We can conclude that OFDM systems outperform CDMA system in terms of BER. [3]
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Comparison in Terms of Complexity CDMA systems have been known to be more complex than OFDM systems. The reason behind this is the fact that CDMA has a higher computational complexity over OFDM due to the traditional equalization techniques it uses, and this complexity increases as the signal bandwidth increases. When we increase the bandwidth of the signal, the effective span in the symbols of the channel impulse response also increases, making the complexity of the CDMA system be of O(N 2 ), as opposed to the well-known complexity of O(Nlog(N)) for OFDM systems. With this complexity, CDMA has no chance in competing with OFDM, as industries always look for the less complex system to implement, and at this rate, the OFDM clearly wins. The only way in which CDMA can somewhat compete with OFDM, is by introducing two techniques. One of which is in the multi-channel option, where multiple neighbouring narrowband channels are used in order to synthesize a wider bandwidth channel. The other technique involves the use of frequency-domain equalization in single carrier systems. This technique basically uses the same Fast-Fourier Transform mechanism used in OFDM, and which, in turn, has the same complexity. With the use of these two techniques, CDMA gains a competitive edge when it comes to comparing it with OFDM, but OFDM remains the best choice in terms of complexity. [4]
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Conclusion In this report, we discussed the two competing network access technologies CDMA and OFDM and described them both. We also compared them both in terms of performance and complexity. We can conclude that OFDM has a better BER over CDMA and therefore outperforms it. In terms of complexity, OFDM is still advantageous; even if CDMA uses the two options (i.e. multi-carrier and single-carrier system) that somewhat give it a competitive edge in terms of complexity.
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References: 1 – “CDMA and OFDM: The convergence of wireless broadband services” September 2008, Pages: 1-14 < ; 2- Lawrey, Eric, “The suitability of OFDM as a modulation technique for wireless telecommunications, with a CDMA comparison.” October 1997 < > 3- Kumar, Rajiv et al. “Comparison of CDMA and OFDM Using Simulink”, International Journal of Wireless Communication and Simulation, Volume 2 Number 1 (2010) pp. 39-50 4- Mailander, Laurence, “Complexity Comparison of OFDM and CDMA for Wideband Communication Systems”, 2007, pages: 1-5, <ieeexplore.ieee.org/iel5/4109264/4109265>
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  • Spring '10
  • hafez
  • Code division multiple access, Channel access method, Orthogonal frequency-division multiplexing

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