First-Hand:Gigabit Wireless Networks

Contributed by: Arogyaswami J. Paulraj, Helmut Bölcskei, Rohit U. Nabar, and Dhananjay A. Gore

Gigabit Wireless Networks

The first decade of the 2000s saw significant expansion of broadband wireless communications. From short range (Bluetooth), to Local Area (WiFi) to Mobile Data (WiMAX and LTE), all wireless networks witnessed rapid increases in data rates. In February 2004 the Proceedings of the IEEE devoted an issue to Gigabit Wireless networks.

The lead article offered an overview of the technology challenges and suggested MIMO (Multiple Input Multiple Output) antennas as the key ingredient for reaching gigabit speeds. This paper proved to be very influential and was downloaded 10,085 times over the next six years; it has been cited on Google Scholar 1,102 times as the technology bore commercial fruit.

The paper suggested that MIMO offered the best leverage to reach one gigabit speeds. The MIMO wireless concept originated in 1991 at Stanford University with Bell Labs staff advancing its theoretical grounding in the late 1990s. In 1998 the lead author of the paper, Stanford Professor Arogyaswami J. Paulraj, founded the first company, Gigabit Wireless (later named Iospan Wireless), to build a MIMO wireless fixed broadband access system, based on MIMO and Orthogonal Frequency Division Multiple Access (OFDMA). Stanford postdoc Helmut Bölcskei helped cofound the company and the other two authors, Dhananjay A. Gore and Rohit U. Nabar, worked there as interns. Iospan built a commercial, broadband, fixed cellular, wireless system that reached a peak spectral efficiency of 10 bps/Hz and a data rate of 18 Mbps using a 2-stream MIMO system in 2001-2. In the following year Paulraj, Nabar, and Gore collaborated on a pioneering text book on the subject.

Less than eight years after the publication of the paper, in January 2012, Broadcom Corporation introduced the first IEEE 802.11ac WiFi chips that exceeded one gigabit throughput. Today, in mid-2012, one can find MIMO-enabled WiFi gigabit routers on sale for well under $100. Paulraj and his co-authors noted in their Proceedings paper that “Gigabit rates in mobile systems cannot be far off.” Indeed, LTE Release 10 mobile networks that are expected to be deployed in 2013-14 will break that barrier. Also, the recent WiGig alliance that promotes 60 GHz technology in short-range wireless networks is calling for speeds exceeding 6 gigabits. Broadband wireless continues to greatly benefit from MIMO as well as from the stunning improvements in semiconductor technology.

References

A. J. Paulraj, D. A. Gore, R. U. Nabar, and H. Bölcskei, “An Overview of MIMO Communications - A Key to Gigabit Wireless,” Proc. IEEE Vol. 92, No. 2 (February 2004), p. 198-218.

Arogyaswami J. Paulraj, Rohit U. Nabar, and Dhananjay A. Gore, Introduction to Space-Time Wireless Communications (Cambridge University Press: 2003), www.stanford.edu/group/introstwc/, accessed 23 July 2012.