A MIMO-OFDM Testbed for Wireless Local Area Networks

We describe the design steps and final implementation of a MIMO OFDM prototype platform developed to enhance the performance of wireless LAN standards such as HiperLAN/2 and 802.11, using multiple transmit and multiple receive antennas. We first describe the channel measurement campaign used to characterize the indoor operational propagation environment, and analyze the influence of the channel on code design through a ray-tracing channel simulator. We also comment on some antenna and RF issues which are of importance for the final realization of the testbed. Multiple coding, decoding, and channel estimation strategies are discussed and their respective performance-complexity trade-offs are evaluated over the realistic channel obtained from the propagation studies. Finally, we present the design methodology, including cross-validation of the Matlab, C++, and VHDL components, and the final demonstrator architecture. We highlight the increased measured performance of the MIMO testbed over the single-antenna system.

[1]  P. Pajusco,et al.  Radio propagation in urban small cells environment at 2 GHz: experimental spatio-temporal characterization and spatial wideband channel model , 2000, Vehicular Technology Conference Fall 2000. IEEE VTS Fall VTC2000. 52nd Vehicular Technology Conference (Cat. No.00CH37152).

[2]  Giuseppe Caire,et al.  A MIMO-OFDM Testbed for Wireless Local Area Networks , 2005, ASILOMAR 2005.

[3]  Giuseppe Caire,et al.  Impact of signal constellation expansion on achievable diversity in quasistatic multiple antenna channels , 2004, 2004 12th European Signal Processing Conference.

[4]  Helmut Bölcskei,et al.  Impact of the propagation environment on the performance of space-frequency coded MIMO-OFDM , 2003, IEEE J. Sel. Areas Commun..

[5]  Maxime Guillaud.  Full-rate full-diversity space-frequency coding for MIMO OFDM systems , 2002 .

[6]  Ari Hottinen,et al.  Minimal non-orthogonality rate 1 space-time block code for 3+ Tx antennas , 2000, 2000 IEEE Sixth International Symposium on Spread Spectrum Techniques and Applications. ISSTA 2000. Proceedings (Cat. No.00TH8536).

[7]  Siavash M. Alamouti,et al.  A simple transmit diversity technique for wireless communications , 1998, IEEE J. Sel. Areas Commun..

[8]  D.T.M. Slock,et al.  Signal processing challenges for wireless communications , 2004, First International Symposium on Control, Communications and Signal Processing, 2004..

[9]  Rodolphe Vauzelle,et al.  A 3D ray-tracing tool for broadband wireless systems , 2001, IEEE 54th Vehicular Technology Conference. VTC Fall 2001. Proceedings (Cat. No.01CH37211).

[10]  A. Robert Calderbank,et al.  Space-Time block codes from orthogonal designs , 1999, IEEE Trans. Inf. Theory.

[11]  Karine Gosse,et al.  MTMR channel estimation and pilot design in the context of space-time block coded OFDM-based WLANs , 2002 .

[12]  Joseph J. Boutros,et al.  Turbo Coding and Decoding for Multiple Antenna Channels , 2003 .

[13]  Giuseppe Caire,et al.  Limiting performance of block-fading channels with multiple antennas , 2001, IEEE Trans. Inf. Theory.

[14]  Dirk T. M. Slock,et al.  Multi-stream coding for MIMO OFDM systems with space-time-frequency spreading , 2002, The 5th International Symposium on Wireless Personal Multimedia Communications.

[15]  Emre Telatar,et al.  Capacity of Multi-antenna Gaussian Channels , 1999, Eur. Trans. Telecommun..

[16]  Vinko Erceg.  IEEE P802.11 Wireless LANs TGn Channel Models , 2004 .

[17]  Helmut Bölcskei,et al.  MIMO wireless channels: capacity and performance prediction , 2000, Globecom '00 - IEEE. Global Telecommunications Conference. Conference Record (Cat. No.00CH37137).

[18]  Reinaldo A. Valenzuela,et al.  Keyholes, correlations, and capacities of multielement transmit and receive antennas , 2002, IEEE Trans. Wirel. Commun..

[19]  Patrice Pajusco,et al.  A Versatile Propagation Channel Simulator for MIMO Link Level Simulation , 2007, EURASIP J. Wirel. Commun. Netw..

[20]  Reinaldo A. Valenzuela,et al.  V-BLAST: an architecture for realizing very high data rates over the rich-scattering wireless channel , 1998, 1998 URSI International Symposium on Signals, Systems, and Electronics. Conference Proceedings (Cat. No.98EX167).

[21]  Dirk T. M. Slock,et al.  Colocated antenna arrays: design desiderata for wireless communications , 2002, Sensor Array and Multichannel Signal Processing Workshop Proceedings, 2002.

[22]  M. J. Gans,et al.  On Limits of Wireless Communications in a Fading Environment when Using Multiple Antennas , 1998, Wirel. Pers. Commun..

[23]  Giuseppe Caire,et al.  Power control and beamforming for systems with multiple transmit and receive antennas , 2002, IEEE Trans. Wirel. Commun..