Uppsala universitet

Narrowband and Broadband Multiuser Detection Using a Multivariable DFE

Claes Tidestav, Anders Ahlén and Mikael Sternad

6th International IEEE Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC'95),
Toronto, Canada, September 27-29 1995, pp 732-736. © 1995 IEEE.

In future cellular systems, so-called smart antennas will be very important. One way of realizing such a smart antenna is via a multivariable DFE. The multivariable DFE can also be used as a multiuser detector in DS-CDMA systems to decrease the sensitivity of the system to the near-far problem.

In this paper, we present a multivariable minimum mean square error (MMSE) DFE, which has the ability to operate on channels with different number of inputs and outputs. It is derived under the constraint of realizability and is calculated by solving a system of linear equations. The suggested DFE can be used for combined temporal and spatial equalization, as well as for narrowband, multiuser detection in systems with multiple antenna elements. The DFE may also serve as a multiuser detector in DS-CDMA systems.

Simulations indicate that the DFE performs well as a multiuser detector. In a system with multiple antennas, it outperforms a corresponding detector for a single user in terms of BER while doubling the capacity. If utilized for multiuser detection in CDMA, its performance is comparable to the best achievable performance of the decorrelating detector, and is attained at a substantially lower computational.

Related publications:
PhD Thesis by Claes Tidestav.
Conference paper in IEEE ICUPC'96, on a DFE for CDMA based on chip-sampled signals.

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