Direct-sequence code-division multiple-access (DS-CDMA) signals are often regarded as a result of the multiplication of the data bits by a spreading sequence, clocked at a higher rate than the data sequence (where the factor of the rates is the spreading factor), cf. figure 1 a. A conceptually different, but equivalent, description is that the symbol rate is raised by up-sampling (repetition en...

The effect of different spreading codes in DWT based MC-CDMA wireless communication system is investigated. In this paper, we present the Bit Error Rate (BER) performance of different spreading codes (Walsh-Hadamard code, Orthogonal gold code and Golay complementary sequences) using Forward Error Correction (FEC) of the proposed system. The data is analyzed and is compared among different sprea...

The two-dimensional (2D) block spread code division multiple access (CDMA) can avoid the uplink multiple-access interference with low-complexity single-user detection in a slow fading channel and, therefore, is very attractive. In the 2D spreading, orthogonal variable spreading factor (OVSF) is used for spreading; an important problem is how to efficiently assign the limited resource of OVSF co...

Direct-sequence code-division multiple-access (DS-CDMA) signals are often regarded as a result of the multiplication of the data bits by a spreading sequence, which is clocked at a higher rate than the data sequence (where the ratio of the rates is the spreading factor), cf. figure 1 a. A conceptually different, but equivalent, description is that the symbol rate is raised by up-sampling (repet...

— This paper proposes an algorithm to search a family of multiple sets of minimum correlated one dimensional uni-polar (optical) orthogonal codes (1-DUOC) or optical orthogonal codes (OOC) with fixed as well as variable code parameters. The cardinality of each set is equal to upper bound. The codes within a set can be searched for general values of code length 'n', code weight 'w', auto-correla...

A novel chaotic spreading sequences for multi-carrier direct sequence code division multiple access (MCDS/CDMA) system is proposed. With this spreading sequence in the MC-DS/CDMA system, the effect of multiple access interference can be mitigated by choosing the spreading sequences with appropriate crosscorrelation properties. The performance of the system is assayed in the multiuser environmen...

In this paper, a neural network based direct sequence spread spectrum code synchronization system is proposed. This system is based on training a recurrent random neural network (RNN) model on all the possible phases of the used spreading code. The trained network can then be used at the receiver for the initial coarse alignment of the local code phase and the received code. One advantage of th...

The study in this paper underlines the importance of correct joint selection of the spreading codes for uplink of multicarrier code division multiple access (MC-CDMA) at the transmitter side and detector at the receiver side in the presence of nonlinear distortion due to high power amplifier (HPA). The bit error rate (BER) of system for different spreading sequences (Walsh code, Gold code, orth...