Space-time block coding (STBC) has a well-defined niche in the class of space-time codes (STC): compared with other STC schemes, STBC trades-off some transmission rate for high computational efficiency and BER performance. Following the general tutorial course on STC in the previous ICASSP, here we focus on STBC to present a survey of recent and very recent results on this STC scheme, along with several open problems. We begin by setting the goals of fourth generation wireless communication systems and explaining why achieving these goals is a challenge. Then we split the discussion in three main parts: channels without ISI (in narrowband communications), channels with ISI (in broadband communications) and time-varying channels with or without ISI (in fast mobile communications). In each case first we discuss the maximum likelihood (ML)-based receive diversity scheme and its properties. Then we go on to explain how we can achieve the same type of BER performance and computational simplicity using a STBC transmit diversity scheme.

We begin with discussing the case when channel state information (CSI) is available at the receiver, and then show how this assumption can be eliminated by using semi-blind channel estimation algorithms (note that the transmitter does not require CSI in any of the STBC schemes discussed). Also, we discuss differential (for time-invariant channels) and double differential (for time-varying channels) STBC schemes that completely eliminate the need for CSI at the receiver. Most of the results we will present are very recent and hence not yet available in the open literature, such as cyclic ML algorithms for joint channel estimation and symbol detection, differential and double differential STBC schemes, STBC for channels with ISI, diversity results for most general (both frequency- and time- selective) channel models, and so on. In addition, some of the open problems we will discuss are significant, such as the existence of generalized 1/1-rate STBC for complex symbols, full double-differential STBC, and 3/4-rate STBC for channels with ISI.

G. B. Giannakis received his Diploma in Electrical Engineering from the National Technical University of Athens, Greece, 1981. From September 1982 to July 1986 he was with the University of Southern California (USC), where he received his MSc. in Electrical Engineering, 1983, MSc. in Mathematics, 1986, and Ph.D. in Electrical Engineering, 1986. After lecturing for one year at USC, he joined the University of Virginia in 1987, where he became a professor of Electrical Engineering in 1997. Since 1999 he has been a professor with the Department of Electrical and Computer Engineering at the University of Minnesota, where he now holds an ADC Chair in Wireless Telecommunications.

His general interests span the areas of communications and signal processing, estimation and detection theory, time-series analysis, and system identification -- subjects on which he has published more than 150 journal papers, 300 conference papers, and two edited books. Current research topics focus on transmitter and receiver diversity techniques for single- and multi-user fading communication channels, precoding and space-time coding for block transmissions, multicarrier, and wide-band wireless communication systems.

G. B. Giannakis is the (co-) recipient of four best paper awards from the IEEE Signal Processing (SP) Society (1992, 1998, 2000, 2001). He also received the Society's Technical Achievement Award in 2000. He co-organized three IEEE-SP Workshops, and guest (co-) edited four special issues. He has served as Editor in Chief for the IEEE SP Letters, as Associate Editor for the IEEE Trans. on Signal Proc. and the IEEE SP Letters, as secretary of the SP Conference Board, as member of the SP Publications Board, as member and vice-chair of the Statistical Signal and Array Processing Technical Committee, and as chair of the SP for Communications Technical Committee. He is a member of the Editorial Board for the Proceedings of the IEEE, and the steering committee of the IEEE Trans. on Wireless Communications. He is a Fellow of the IEEE, a member of the IEEE Fellows Election Committee, the IEEE-SP Society's Board of Governors, and a frequent consultant for the telecommunications industry.