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For the time-frequency overlapped signals, a low-complexity single-channel blind source separation (SBSS) algorithm is proposed in this paper. The algorithm does not only introduce the Gibbs sampling theory to separate the mixed signals, but also adopts the orthogonal triangle decomposition-M (QRD-M) to reduce the computational complexity. According to analysis and simulation results, we demonstrate that the separation performance of the proposed algorithm is similar to that of the per-survivor processing (PSP) algorithm, while its computational complexity is sharply reduced.

In Residue Number System-based systems, how to select moduli set and evaluate its performance is an important issue. The objective of this study is to propose a systemic performance evaluation method for RNS based on the properties of moduli set. By abstracting the inherent properties of moduli sets, such as the complexity of arithmetic units, utilization ratio of dynamic range, parallelism and balance between residue channels, this method can provide advices on moduli set selection and carry out performance estimation before circuits implementation. Furthermore, we also propose a new multi-channel moduli set by introducing a new radix component in this paper. Performance analysis and comparison results show that the proposed multi-channel moduli set has better performance of dynamic range utilization ratio, parallelism and balance than that of the commonly used moduli set with the same number of channels.

In the paper, a new time-delay estimation algorithm, which is based on the cyclic auto-correlation function, is proposed for single-channel two mixed OFDM signals without data-aided. In the method, the linear equations on time delay parameters are constructed from different cyclic autocorrelation functions, and the closed-form solutions are obtained by solving the equations without any prior information of fading parameter and shaping filter. Besides, it also analyzes the Cramer-Rao bound of time-delay estimation of mixed OFDM signal, and verifies the effectiveness of the proposed method through computer simulation. The analysis and simulation results show that the proposed algorithms can achieve good blind estimation for the time delay of mixed OFDM signal in a single channel.

In this paper, we propose a new design method of interleavers for interleave-division multiple access (IDMA) system, 2-dimension interleavers. Through a same interleaving rule Gamma, we scramble the row indices and column indices of a traditional block interleaving matrix, and obtain an interleaver. We mark this interleaver as master interleaver. Different interleavers are generated by circular shifting master interleaver. Besides, we prove that the minimum distance between two adjacent bits resulted from 2-dimension interleavers is much larger than random interleavers. The simulation results show that 2-dimension interleavers achieve much better performance with much less resource consumption compared to random interleavers in IDMA systems.

The interleave division multiple access (IDMA) relies on the interleavers as the only means to separate users. In this paper, we analyze the multiple access interference (MAI) performance of interleavers and propose a new design method for interleavers with lower complexity and less memory consumption: shifting interleavers. A series of interleavers can be generated by circular shifting a specific pseudo noise (PN) interleaver, which is generated by a PN sequence generator. Thus, the architecture of the proposed interleaver is much simpler than that of other interleaver schemes for IDMA systems. The simulation results show that shifting interleavers can achieve the same performance with much less resource consumption compared to random interleavers in the IDMA systems.