Serial Interference Cancellation Research Articles

Space-time multiuser detection for DS-CDMA communication in MIMO systems

Space-time signal processing based on multiple-input multiple-output(MIMO) systems is an active research field in which interfering signals are cancelled and multiuser detection is achieved using space diversity. In a Rayleigh fading channel, space-time block codes using multiple transmitting antennas can improve system performance and reduce bit-error-rate for multiuser detection. In this paper, several antenna configurations are designed for DS-CDMA communication in MIMO systems. Space-time linear multiuser detection and space-time serial interference cancellation multiuser detection are simulated. Bit-error-rate and computation complexities of the two methods are compared. Conclusions are given in the end.

Performance Enhancement of SC/S-MMSE Turbo Receiver for MIMO-SDM/OFDM Transmission

This paper aims to improve the performance of the soft canceller followed by simplified minimum mean-square error (SC/S-MMSE) turbo receiver [11] for multiple-input and multiple-output space-division multiplexing/orthogonal frequency division multiplexing (MIMO-SDM/OFDM) transmission; it performs iterative parallel soft interference cancellation and MMSE filtering, and stream-wise soft-input and soft-output decoding. For this aim, we newly introduce two detection techniques: 1) serial interference cancellation, and 2) cyclic redundancy check (CRC)-assisted interference cancellation and MMSE filter tap computation. Various computer simulations are conducted to evaluate the performance enhancement obtained via the use of the two detection techniques. The computer simulation results show that this paper's proposed serial SC/S-MMSE turbo receiver with CRC achieves frame error rate (FER) performance gain over existing MIMO receivers (MMSE receiver, V-BLAST receiver, parallel SC/MMSE-matched filter (MF) turbo receiver, and parallel SC/S-MMSE turbo receiver) for QPSK, 16QAM and 64QAM modulation while keeping the comparable complexity order.

Novel two-dimensional multistage interference cancellation scheme for uplink transmission of single carrier cyclic prefix-assisted CDMA system

A two-dimensional multistage interference cancellation scheme for the uplink transmission of a high-speed single carrier cyclic prefix-assisted CDMA system is proposed. In this two-dimensional scheme, equalisation and interference regeneration is performed in the frequency domain while data decision and interference subtraction is done in the time domain. Two variations of this scheme are proposed. They are a serial multistage interference cancellation scheme and a hybrid scheme combining the serial and parallel multistage interference cancellation methods. The second scheme has considerable reduction in the processing delay over the first one at the cost of higher hardware complexity. The performance of both schemes is evaluated by extensive computer simulations.

Reduced complexity serial interference cancellation for CDMA receivers

A method to significantly reduce the computational complexity of a serial interference cancellation scheme for CDMA receivers, while maintaining the receiver performance, is presented. The reduced complexity is achieved by accelerating the convergence rate of the algorithm with a preconditioning technique.

Channel estimation and multiuser detection in long-code DS/CDMA systems

The problems of channel estimation and multiuser detection for direct sequence code division multiple access (DS/CDMA) systems employing long spreading codes are considered. With regard to channel estimation, several procedures are proposed based on the least-squares approach, relying on the transmission of known training symbols but not requiring any timing synchronization. In particular, algorithms suited for the forward and reverse links of a single-rate DS/CDMA cellular system are developed, and the case of a multirate/multicode system, wherein high-rate users are split into multiple virtual low-rate users, is also considered. All of the proposed procedures are recursively implementable with a computational complexity that is quadratic in the processing gain, with regard to the issue of multiuser detection, an adaptive serial interference cancellation (SIC) receiver is considered, where the adaptivity stems from the fact that it is built upon the channel estimates provided by the estimation algorithm. Simulation results show that coupling the proposed estimation algorithms with a SIC receiver may yield, with a much lower computational complexity, performance levels close to those of the ideal linear minimum mean square error (MMSE) receiver, which assumes perfect knowledge of the channels for all of the users and which (in a long-code scenario) has a computational complexity per symbol interval proportional to the third power of the processing gain.

Frequency-hopping versus interference cancellation for TD-CDMA

This work considers asynchronous time division code division multiple access (TD-CDMA) systems with RAKE receivers and one stage of parallel interference cancellation (PIC) or serial interference cancellation (SIC). A general method based on the concept of spherically symmetric signals is presented for the evaluation of the average probability of error of uncoded TD-CDMA systems. Slow frequency-hopping (SFH) with frequency overlap (FO) between adjacent carriers and interference cancellation are also included in the analysis, which considers the multipath Rayleigh fading channel (which models indoor and outdoor vehicular radio propagation). We analyze quadrature phase shift keying (QPSK) modulation with coherent demodulation and multipath (frequency) diversity with maximal ratio combining (MRC). Power control, adaptive SFH, and interference cancellation are employed for improving the bit-error rate (BER) performance. It is found that the scheme with SFH, in spite of the FO, always improves the performance substantially, and interference cancellation, in general, provides the highest BER improvement.

Serial interference cancellation method for CDMA

A serial interference canceller for CDMA is proposed, where progressive stages in the canceller strip away the noise. For 31 chip Gold codes, 17 users, and imperfect power control, the proposed canceller can obtain an average BER of 4 × 10-6 compared with 3 × 10-3 for a parallel canceller after four stage cancellations. The delay penalty is 21 bit periods.