Abstract
Chi et al. proposed a fast kurtosis maximization algorithm (FKMA) for blind equalization/deconvolution of multiple-input multiple-output (MIMO) linear time-invariant systems. This algorithm has been applied to blind multiuser detection of single-rate direct-sequence/code-division multiple-access (DS/CDMA) systems and blind source separation (or independent component analysis). In this paper, the FKMA is further applied to blind multiuser detection for multirate DS/CDMA systems. The ideas are to properly formulate discrete-time MIMO signal models by converting real multirate users into single-rate virtual users, followed by the use of FKMA for extraction of virtual users' data sequences associated with the desired user, and recovery of the data sequence of the desired user from estimated virtual users' data sequences. Assuming that all the users' spreading sequences are given a priori, two multirate blind multiuser detection algorithms (with either a single receive antenna or multiple antennas), which also enjoy the merits of superexponential convergence rate and guaranteed convergence of the FKMA, are proposed in the paper, one based on a convolutional MIMO signal model and the other based on an instantaneous MIMO signal model. Some simulation results are then presented to demonstrate their effectiveness and to provide a performance comparison with some existing algorithms.
Highlights
Direct-sequence/code-division multiple access (DS/CDMA) has been widely used in multiuser cellular wireless communications (e.g., 2G, 3G, and ultra-wideband systems) due to efficient spectrum utilization, release from frequency management, low mobile station’s transmit power through power control [1], and high multipath resolution, and so forth [2,3,4,5,6,7,8]
With growing demands for multimedia services in wireless communication systems, there has been a need to provide a platform of high-speed multirate for the transmission of image, video, voice, and data such as variable chip rate (VCR), variable processing gain (VPG), and multicode (MC) DS/CDMA systems [9,10,11,12,13,14,15,16,17]
Given by (9) and the other associated with the instantaneous multiple-input multiple-output (MIMO) signal model y[n] given by (24)), Ma and Tugnait’s blind code-constrained inverse filter criteria (CC-IFC) algorithm [13], and the blind minimum variance (MV) receiver proposed by Tsatsanis et al [11] and Tsatsanis and Xu
Summary
Direct-sequence/code-division multiple access (DS/CDMA) has been widely used in multiuser cellular wireless communications (e.g., 2G, 3G, and ultra-wideband systems) due to efficient spectrum utilization, release from frequency management, low mobile station’s transmit power through power control [1], and high multipath resolution, and so forth [2,3,4,5,6,7,8]. With growing demands for multimedia services in wireless communication systems, there has been a need to provide a platform of high-speed multirate for the transmission of image, video, voice, and data such as variable chip rate (VCR), variable processing gain (VPG) (which is called variable sequence length), and multicode (MC) DS/CDMA systems [9,10,11,12,13,14,15,16,17]. For VCR systems, each user uses a spreading sequence of the same length (i.e, different rate users use different chip rates), resulting in that the available bandwidth is not fully used by the low-rate users, whereas the VPG and MC systems avoid this problem. For VPG systems, users with different data rates are accommodated over the same bandwidth (and so a constant chip rate for each user) with the assignment of spreading sequences of different lengths. The VPG and MC access schemes have been adopted for 3G wireless communication systems [4, 5]
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