My research focuses on wireless communications with the aim of increasing transmission rates for multihop wireless networks, as well as reducing the cost and extending the service life of the individual network nodes. It builds on and expands the my previous work on the subject of space-time diversity in wireless communications. It extends towards cooperative diversity methods in CDMA ad-hoc networks with RAKE receivers and MIMO systems.

This work's benefit is to make multi-hop wireless networks more powerful by increasing user capacity, service capability, and individual unit flexibility and service life. An example of such a system is a network of communication units used by different parties (rescuers, medical teams, etc.) in a rescue or disaster relief operation. Such networks are increasingly essential for civil and commercial infrastructures, crisis monitoring, and public safety. The research endeavors to increase the sustainable number of active users in the network which makes the service more affordable. It also strives for higher transmission rates which results in more powerful and flexible services for users. This work further benefits commercial technology, research endeavors, and public safety by improving the power efficiency of the network nodes. The improved efficiency implies smaller, more affordable units. In sensor networks, this means the ability to deploy more units. This effect, added to the nodes' extended service lives result in a more powerful network.

Our work is a novel framework of cooperative multi-input-multi-output (MIMO) diversity schemes in CDMA wireless multi-hop networks, where none of the nodes have multiple antennas. Using clusters of network nodes to relay wholly or partially correlated information to its destination both to increase effective rates and extend the nodes' service lives are concepts which are not fully developed. These proposed systems can truly achieve MIMO-type performance in a distributed way due to the use of coarse transmitter synchronization schemes complemented by RAKE receivers.

Here is a list of publications:

	Alejandra Mercado and Babak Azimi-Sadjadi, Power Efficient Link for Multi-Hop Wireless Networks,  41st Annual Allerton Conference on Communication, Control, and Computing; University of Illinois, October 2003.
	Alejandra Mercado and K.J. Ray Liu, Rate Control for DS-CDMA Channels Using Power Control and Short Orthogonal Pseudo Random Codes,  IEEE Vehicular Technology Conference, Atlantic City, NJ, October 2001. Volume 3, pages 1716-1720.
	Alejandra Mercado and K.J. Ray Liu, Adaptive QoS for Mobile Multimedia Applications with Power Control and Smart Antennas, ICC 2000 (IEEE Communications Society), New Orleans, June 2000. Volume 1, pages 60-64.
	Alejandra Mercado and K.J. Ray Liu, NP-Hardness of the Stable Matrix in Unit Interval Family Problem in Discrete Time,  Systems and Control Letters, volume 42, issue 4, pp. 261-265, April 2001. Download in pdf format.
	Alejandra Mercado and K.J. Ray Liu, Adaptive QoS for Mobile Multimedia Services over Wireless Networks, IEEE International Conference on Multimedia and Expo, New York, July-August 2000. Volume 1, pages 517-520.
	Alejandra Mercado and K.J. Ray Liu, Adaptive QoS for Wireless Multimedia Networks Using Power Control and Smart Antennas, accepted to IEEE Transactions on Vehicular Technology. Download in pdf format.

Ph.D. Dissertation:

-	"Adaptive Quality of Service or Integrated Multimedia Over Wireless Networks" Download in PostScript format, or Download in pdf format.

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