MC-CDMA

Multi Carrier Code Division Multiple Access (MC-CDMA) is an attractive choice for high speed wireless communication as it avoids the problem of Inter Symbol Interference (ISI) and also exploits frequency diversity. In order to support multiple users with high speed data communications, the MC-CDMA technique is used to address these challenges. MC-CDMA experiences severe multipath fading which badly affects its performance. When transmission over fading channel multi-cell interference occurs and this degrades the performance of the system. This paper specially analyzes the BER performance under Rayleigh fading channel conditions of MC-CDMA in presence of AWGN (Additive White Gaussian Noise) using BPSK modulation for different number of subcarrier, different number of users using MATLAB program, and finally the paper also presents a comparison between simulated results, which shows the reduction in BER performance.

this paper reviews the state of the technique of
field programmable gate array (FPGA) for partial
Reconfiguration (PR), design methodologies of Wireless
Communication System, such as Multi Carrier Code Division
Multiple Access (MC-CDMA) technique has been to be suited for
future wireless systems that are expected to provide higher data
rates and greater flexibility for the services of voice, data, video
and Internet to the users due to its property in using the
bandwidth in efficient manner. The Software Defined Radio is
considered as a wireless system applied by routines so as
software. Consequently, the use of SDR allows vehicle
manufacturers to familiarize communication applications
sustained through cars to appropriate to the standards of the
respected country presented in the object oriented programming.
FPGAs are playing a very significant role in SDR. However, in
modern wireless communication system programs, SDR and CR
need to design a wide range of waveforms complex, which it is
complicated in design and performance and implementation
needs more time. The design of the modulation and
demodulation and other signal processing application of PR
technique that have the ability to modify blocks of logic
dynamically by downloading partial bit files, while the remaining
logic is still working without interruption; thus, power
consumption and configuration time can be saved for a larger
extent. The PR using was allowed to move for fewer or smaller
devices as, decrease power and increase system upgradability.

MC CDMA is a rising candidate for future generation broadband wireless communication and gained great attention from researchers. It provides benefits of both OFDM and CDMA. Main challenging problem of MC CDMA is high PAPR. It occurs in HPA and reduces system efficiency. There are many PAPR reduction techniques for MC CDMA. In this paper we proposed Ant colony optimization algorithm to reduce PAPR with different number of user using BPSK and QPSK modulation. ACO is a metaheuristic technique and based on the foraging behavior of real ants. It provides solution to many complex problems. Simulation result proves that ACO using BPSK modulation is effective for reducing PAPR in MC CDMA.

Multi Carrier Code Division Multiple Access (MC-CDMA) isa well known techniquefor highs peed wireless data transmission .Two advanced technologywas included in the MC-CDMA structure, such as orthogonal frequency division multiplex(OFDM) and the code division multiple access (CDMA),so that it benefits from the robustness of OFDM against multipath environment and from the capability of multiusermultiplexingservices that is achieved via (CDMA) system. MC-CDMA is a multicarrier spread spectrum system which is classified as the candidate scheme for future mobile radio systems.In this paperMC-CDMA system, with Rayleigh fading channel and 16QAM array modulation, was simulatedto investigate the effects of different parameters on the system performance, such as processing gain; number of paths; number of users;interleaving;and coding ratio.MC-CDMA performances can be considerably improved by proper selection of these parameters. As expected, results shows that MC-CDMA has a better performance overCDMA system.

Increasing data rate and high performance is the target focus of wireless communication. The multi
carrier on multi-hop communication system using relay's diversity technique which is supported by a
reliable coding is a system that may give high performance.
This research is developing a model of multi user and two scheme of multi carrier CDMA on multi hop
communication system with diversity technique which is using Alamouti codes in Rayleigh fading channel.
By Alamouti research, Space Time Block Code (STBC) for MIMO system can perform high quality signal
at the receiver in the Rayleigh fading channel and the noisy system. In this research, MIMO by STBC is
applied to single antenna system (Distributed-STBC/DSTBC) with multi carrier CDMA on multi hop
wireless communication system (relay diversity) which is able to improve the received signal performance.
MC DS CDMA on multi hop wireless communication system with 2 hops is better performing than MC
CDMA on multi user without Multi User Detector. To reach BER 10-3 multi hop system with MC CDMA
needs more power 5 dB than MC DS CDMA at 5 users using Alamouti scheme for symbol transmission at
the relay.

In this paper, the impact of Forward Error Correction (FEC) code namely Trellis code with interleaver on the performance of wavelet based MC-CDMA wireless communication system with the implementation of
Alamouti antenna diversity scheme has been investigated in terms of Bit Error Rate (BER) as a function of Signal-to-Noise Ratio (SNR) per bit. Simulation of the system under proposed study has been done in M-ary modulation schemes (MPSK, MQAM and DPSK) over AWGN and Rayleigh fading channel incorporating Walsh Hadamard code as orthogonal spreading code to discriminate the message signal for individual user. It is observed via computer simulation that the performance of the interleaved coded based proposed
system outperforms than that of the uncoded system in all modulation schemes over Rayleigh fading channel

A power allocation algorithm for projection matrix
receiver based MC-CDMA system named Adaptive Threshold
SAFNAQ (AT-SAFNAQ), has been proposed. SAFNAQ is a
combination of frequency domain (FDPA) and eigenvector based
(EBPA) power allocation algorithms. SAFNAQ algorithm does
not optimize threshold value and it uses same threshold value
over different channel realizations. In AT-SAFNAQ, the receiver
has an extra unit compared to the receiver used in SAFNAQ
algorithm. This extra unit optimizes threshold level adaptively.
In accordance with optimum threshold value and the subcarrier
gains, the feedback vector is sent to the transmitter for allocation of power. We have compared our results with no power allocation, FDPA, EBPA and SAFNAQ. Simulation results show that AT-SAFNAQ algorithm provides noticeable improvement in performance compared to the algorithms available in literature. We have generated testing bits at transmitter end, passed through  Rayleigh fading channel to calculate BER performance of the system at receiver end to verify the results. Moreover, Variances of BER for different users are explored to show that in our system all the users have equal priority.

In Communication system, the system capacity and performance are adversely affected and degraded by interference.
Hence, power control plays a prominent role in an  interference-limited system, which increases the efficiency by mitigating the
adjacent and co-Channel interference in the system.
In this paper, primarily power control is said to be used in maintaining the acceptable Carrier to Interference Ratio (CIR) by meeting
some Quality of service (QoS) requirements Objective function that is defined as maximum channel capacity in a power constraint
scenario. The signals in a radio channel undergo different propagation effects like reflection, refraction, scattering  and shadowing.
Hence, the distribution of users across subcarrier groups as well as their transmission powers within a given cell has a significant
effect on how users and power are accordingly distributed elsewhere in the network to maximize the capacity  of the system thereby
enhancing its performance by the multiple carrier code division multiple access (MC-CDMA).

Abstract—In this paper, a comparative study between a blind
algorithm, based on higher order cumulants, and adaptive
algorithms, i.e. Recursive Least Squares (RLS) and Least
Mean Squares (LMS) forMultiCarrier Code DivisionMultiple
Access (MC-CDMA) systems equalization is presented. Two
practical frequency-selective fading channels, called Broad-
band Radio Access Network (BRAN A, BRAN B) normal-
ized for MC-CDMA systems are considered. In the part of
MC-CDMA equalization, the Zero Forcing (ZF) and the Min-
imum Mean Square Error (MMSE) equalizer techniques were
used. The simulation results in noisy environment and for
different signal to noise ratio (SNR) demonstrate that the
blind algorithm gives approximately the same results ob-
tained by adaptive algorithms. However, the proposed algo-
rithm presents the advantage to estimate the impulse re-
sponse of these channels blindly except that the input exci-
tation is non-Gaussian, with the low calculation cost, com-
pared with the adaptive algorithms exploiting the informa-
tion of input and output for the impulse response channel
estimation.
Keywords—blind identification and equalization, higher order
cumulants, RLS, LMS, MC-CDMA systems.

Grouped MC-CDMA is an efficient system with a number of attractive features. In this paper, we treat the multiuser downlink MC-CDMA system and propose a user grouping and subcarrier allocation algorithm. Given the fading conditions of the subcarriers of all the users, we first adaptively divide the users into groups and then perform subcarrier allocation to each group. This scheme aims to maximize the total system throughput while guaranteeing bandwidthfairness among groups and the rate-fairness among users in the same group. Simulation results are given to demonstrate the performance of the proposed algorithm in terms of stability, spectral efficiency with different number of groups, and BPS(bits per symbol) per user. We also compare the performance of our algorithm with that of random policy. The result shows that our scheme outperforms the random policy.