Acronym | GEODIF |
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Funding Reference | FCT - POSI/38775/CPS/2001 |

Dates | 2002|2004 |

Summary | The spatial division multiple access (SDMA) concept for mobile radio cellular systems has recently attracted much attention. SDMA is a spectral bandwidth saving multiple access technique which provides increased cellular capacity via effective exploitation of the spatial dimension of the radio resource. In SDMA based wireless networks, several users within the same cell share the same time frequency channel, as opposed to the other popular multiple access methodologies, e.g., time division multiple access (TDMA) or frequency division multiple access (FDMA), where each channel is occupied at most by one user at a time. This efficient spectral allocation strategy per cell permits to expand the overall capacity of current cellular infrastructures, without consuming additional radio frequency (RF) bandwidth. From the receiver viewpoint, the SDMA technique raises a new signal processing problem: in addition to suppression of the intersymbol interference (ISI) induced by multipath propagation, the SDMA receiver has to separate the linearly superimposed users. Current research on SDMA architectures focus on developing algorithms capable of resolving linear convolutive mixtures of digital sources. The main goal of this proposal is the optimal design of SDMA receivers based on differential-geometric tools. Here, optimality results from the full exploitation of the data model, with possible incorporation of prior knowledge (Bayesian processing). |

Research Groups |
Signal and Image Processing Group (SIPG) |

ISR/IST Responsible |

[1] João Xavier, Victor Barroso, The Riemannian Geometry of Certain Parameter Estimation Problems with Singular Fisher Information Matrices, IEEE International Conference on Acoustics, Speech and Signal Processing, ICASSP'04, Vol. 2, pp. 1021-1024 , Montreal, Canada, 2004

[2] João Xavier, Victor Barroso, Geodesic Lower Bound for Parametric Estimation with Constraints, Proc. Workshop on IEEE Signal Processing Advances on Wireless Communications, SPAWC'04, Lisbon, Portugal, 2004

[3] João Xavier, Victor Barroso, Paulo Lopes, Blind Source Separation and Channel Identification: Exploiting 2nd-Order Statistics in Bayesian Frameworks, Journal of the Brazilian Telecommunications Society (JTBS), 2004

[4] P. Lopes, João Xavier, Victor Barroso, Exploiting 2nd Order Statistics in Bayesian Signal Reconstruction Problems, Proc. ICASSP2003 - IEEE International Conference on Acoustics, Speech and Signal Processing, Hong-Kong, 2003

[5] T. Patrao, João Xavier, Victor Barroso, An Interior Point Algorithm for Joint Symbol Detection and Multichannel Acquisition in Fast-Fading Narrowband Channels, Proc. SPAWC2003 - 4th IEEE International Workshop on Signal Processing Advances in Wireless Communications, Rome, Italy, 2003