Generalized Multicarrier CDMA: Unification and Linear Equalization

Abstract

<p/> <p>Relying on block-symbol spreading and judicious design of user codes, this paper builds on the generalized multicarrier (GMC) quasisynchronous CDMA system that is capable of multiuser interference (MUI) elimination and intersymbol interference (ISI) suppression with guaranteed symbol recovery, regardless of the wireless frequency-selective channels. GMC-CDMA affords an all-digital unifying framework, which encompasses single-carrier and several multicarrier (MC) CDMA systems. Besides the unifying framework, it is shown that GMC-CDMA offers flexibility both in full load (maximum number of users allowed by the available bandwidth) and in reduced load settings. A novel blind channel estimation algorithm is also derived. Analytical evaluation and simulations illustrate the superior error performance and flexibility of uncoded GMC-CDMA over competing MC-CDMA alternatives especially in the presence of uplink multipath channels.</p

Resource Allocation with Adaptive Spread Spectrum OFDM Using 2D Spreading for Power Line Communications

“…Theorem 2 simply says that maximal throughput is reached when bits and energies are distributed as uniformly as possible across the codes. The optimal reliable throughput then writes (10) and the throughput R k per code are such that R k ∈ { R/L , R/L + 1}. This theorem also gives the number K of codes to use which is L if R/L = 0, and L(2 R/L − 1) otherwise.…”

“…As previously stated, the studied system results from the combination of multicarrier modulation and spread spectrum. In the general case, the data symbols are spread in time and frequency, and OFDM modulation is applied over the chips of the spreading codes, as presented in [10], thus leading to the 2D SS-OFDM waveform which we are interested in. In our study, the SS component is not used to share access between users, as CDMA does, but instead to multiplex different data symbols belonging to a given user.…”

LSF-CMA based blind equalization algorithms for MC-CDMA systems

“…Hence the transmitted 1 vector of chip samples is given by ) = ) (2) Then, one adds a cyclic prefix block such that the 1 top and bottom subvectors are identical, the transmitted vector of length Q=P+N is now given by [5] ) = )…”

Performance Analysis of a Simple Subspace Projection-Based Channel Estimate Improver for Multicarrier CDMA Systems

“…The combination of DS-CDMA and multicarrier modulation was proposed circa 1993 [9], [10]. Since, the idea of integrating the merits of both CDMA and OFDM schemes has attracted significant research interest [11], [12], [13]. Such systems are known as Multicarrier CDMA systems and are based on some combination of DS spreading and OFDM transmission.…”