The tutorial is dedicated to cutting-edge wireless parallel transmission technologies in frequency-domain and space-domain, known as orthogonal frequency-division multiplexing (OFDM) and multiple input multiple out (MIMO) respectively, with focus on the implementations of OFDM MIMO high-speed wireless local area network (WLAN) and wireless metropolitan area network (WMAN) prototypes based on the technology of software radio.

The related technical backgrounds are briefly introduced first. This includes OFDM, MIMO, space-time coding, Bell laboratory layered space-time (BLAST), IEEE 802.11a-based WLAN, IEEE 802.16-based WMAN and software radio testbed. The tutorial then discusses the implementations of a two-transmitter two-receiver (2x2) real-time space-time coding OFDM WLAN/WMAN prototype and a four-transmitter four-receiver (4x4) OFDM BLAST WLAN/WMAN prototype. At first, we discuss the configuration of an up-to-date software radio testbed. The key algorithm implementations based on multiple TMS320C6701 DSPs are then presented, including QAM map/de-map, FFT/IFFT, time synchronization, frequency synchronization, channel estimation and compensation, and coding/decoding. The prototype realizes a 30 Mb/s wireless link based on the IEEE 802.16 standard and Alamouti¹s space-time diversity scheme. Next, we present the experimental results of a four-transmitter four-receiver OFDM BLAST prototype, offering a peak data rate of 525Mb/s with a spectrum efficiency of 19.2 b/s/Hz. BLAST detection algorithms, bit error rate (BER) versus signal to noise ratio (SNR) curves, the impairments of carrier frequency offset, the impact on system capacity due to the degradation of MIMO channel, the error distributions and asymmetric MIMO configurations are discussed in details.

Software radio testbeds can rapidly implement and evaluate new algorithms and schemes, which benefit both academic research and product development. This tutorial is based on our five years¹ research in the software radio laboratory at Georgia Tech and offers fundamental and helpful information for development engineers, system engineers, technical managers, and graduate students who are interested in the promising wireless parallel transmission technologies.

Instructor: Weidong Xiang, University of Michigan, USA

Weidong Xiang received his M.S.E.E. and Ph.D. degrees form Tsinghua University, Beijing, China, in 1996 and 1999, respectively. From 1999 to 2004, he worked as a post-doctoral fellow and then a research scientist at the software radio laboratory (SRL) at Georgia Institute of Technology, Atlanta, Georgia. From September 2004, he is with the Electrical and Computer Engineering Department, University of Michigan-Dearborn, as an Assistant Professor. His research interests include OFDM, MIMO, software radio, smart antenna, wireless LAN/MAN and 3G/4G systems.

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