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CESG Seminar: Cloud Radios with Limited Feedback

September 9, 2014 @ 3:55 pm - 5:00 pm

Room 1034 ETB

Dr. Kiran Kuchi
Associate Professor in the Department of Electrical Engineering at IIT Hyderabad

The evolution of cellular communication networks from 1G through 4G has resulted in a steady increase in the allowable rates for users (UEs). However, other cell interference (OCI) still remains the performance limiting factor. Mitigation of OCI using interference cancellation strategies results in improvement of allowable rates.
This can be achieved by a cloud radio network, which is also labeled as network multipleinput-multiple-output (MIMO) centralized precoding architecture in literature. In a cloud radio network, a group of nearby basestations (BSs) function in cooperation to cancel the interference due to each other. In the downlink, the cloud, which is a collection of multiple BSs, serves a group of users equipments (UEs) simultaneously with multiple streams. These streams are appropriately precoded, so that interference-free decoding is possible at the receiver end.
In this talk, we present the achievable rates for a cloud radio network using a zero forcing (ZF) equalizer with dirty paper precoding (DPC). To simplify the analysis, we use a stochastic geometric framework based on Poisson point processes instead of the traditional grid based cellular network model. We show that when complete channel state information is available at the cloud, rates close to those achievable with total interference cancellation can be achieved. We also study the impact of limiting the channel state information on the achievable rate. Bounds are developed on the achievable rate with limited feedback. These bounds are shown to be tight while permitting analytical tractability. Specifically, we show that with a limited feedback of about 4-6 channel states collecteed from each user, we obtain a 2.5 fold gain in spectral efficiency compared to conventional systems.

Bio: Dr. Kiran Kuchi received B.Tech degree in Electronics and Communications engineering from Sri Venkateswara University college of Engineering Tirupati, in 1995, MS and PhD degrees both in Electrical engineering from The University of Texas at Arlington, Texas, USA, in
1997 and 2006, respectively. Between 2000-2008, he was with Nokia Research, Irving, Texas where he contributed to the development of GSM/EDGE, WiMax and LTE systems. During 2008-2011, he was with Centre of Excellence in Wireless Technology (CEWiT) where he led the 4G research and standardization efforts. He was also an adjunct faculty with the department of Electric Engineering, IIT Madras during this time.

Presently, he is an Associate Professor in the Department of Electrical Engineering at IIT Hyderabad. His current research interests include design and analysis of conventional and cloud cellular systems, MIMO systems, equalization/interference suppression techniques, development of prototypes for next generation communication systems. Dr. Kuchi holds the position of chairman, Radio Access and Spectrum work group of Telecommunications Standards Development Society, India (TSDSI). He is also an editor for IEEE communication Letters. Dr. Kuchi holds 12 US patents and several others are pending.

Host: Dr. Reddy


September 9, 2014
3:55 pm - 5:00 pm