Analysis of the dynamics of iterative interference cancellation in iterative decoding
Problems of Information Transmission
Impact of channel estimation errors on multiuser detection via the replica method
EURASIP Journal on Wireless Communications and Networking - Special issue on advanced signal processing algorithms for wireless communications
Vector precoding in wireless communications: a replica symmetric analysis
Proceedings of the 2nd international conference on Performance evaluation methodologies and tools
Equal power allocation of IDMA systems: feasibility, optimality, and throughput
IEEE Transactions on Wireless Communications
A two-stage capacity-achieving demodulation/decoding method for random matrix channels
IEEE Transactions on Information Theory
Multi-rate communications using layered interleave-division multiple access with power allocation
WCNC'09 Proceedings of the 2009 IEEE conference on Wireless Communications & Networking Conference
Iterative channel and data estimation: framework and analysis via replica method
ISIT'09 Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 4
A new signaling scheme for large DS-CDMA channels without CSI
WiOPT'09 Proceedings of the 7th international conference on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks
On asymptotic performance of iterative channel and data estimation in large DS-CDMA systems
WiOPT'09 Proceedings of the 7th international conference on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks
How much training is needed for iterative multiuser detection and decoding
GLOBECOM'09 Proceedings of the 28th IEEE conference on Global telecommunications
Non-Data-Aided Timing Acquisition for Asynchronous IDMA Systems
Wireless Personal Communications: An International Journal
Hi-index | 754.90 |
We consider a canonical model for coded code-division multiple access (CDMA) with random spreading, where the receiver makes use of iterative belief-propagation (BP) joint decoding. We provide simple density-evolution analysis in the large-system limit (large number of users) of the performance of the BP decoder and of some suboptimal approximations based on interference cancellation (IC). Based on this analysis, we optimize the received user signal-to-noise ratio (SNR) distribution in order to maximize the system spectral efficiency for given user channel codes, channel load (users per chip), and target user bit-error rate (BER). The optimization of the received SNR distribution is obtained by solving a simple linear program and can be easily incorporated into practical power control algorithms. Remarkably, under the optimized SNR assignment, the suboptimal minimum mean-square error (MMSE) IC-based decoder performs almost as well as the more complex BP decoder. Moreover, for a large class of commonly used convolutional codes, we observe that the optimized SNR distribution consists of a finite number of discrete SNR levels. Based on this observation, we provide a low-complexity approximation of the MMSE-IC decoder that suffers from very small performance degradation while attaining considerable savings in complexity. As by-products of this work, we obtain a closed-form expression of the multiuser efficiency (ME) of power-mismatched MMSE filters in the large-system limit, and we extend the analysis of the symbol-by-symbol maximum a posteriori probability (MAP) multiuser detector in the large-system limit to the case of nonconstant user powers and nonuniform symbol prior probabilities.