On the Adaptive Sum-Capacity of Distributed Multiple Access with Individual CSI

Abstract

In wireless communications, a fading multiple-access channel (MAC) is typically used to model the uplink communication. Conventional MACs assume a centralized system, where the transmission rate and power are chosen centrally for every fading vector realization. On the other hand, there is considerable interest in the performance of distributed multiple access systems, where the lack of global channel state information (CSI) demands novel communication strategies. We consider a block-fading MAC where each transmitter is aware only of its own link CSI, which we term as the individual CSI MAC. The receiver has access to the full CSI of all links. This model was recently introduced in the information theory literature, and naturally leads to a distributed access system with several applications. An important utility of interest for this model is known as the power-controlled adaptive sum-capacity, whose evaluation is an open problem. This is the main subject of the current paper. We present the power-controlled adaptive sum-capacity of a wide class of popular fading MAC models. In particular, we characterize the sum-capacity when the statistics of the channel are identical across users. The proposed schemes also allow a low-complexity successive-cancellation decoding using rate-splitting. Furthermore, the optimal schemes are extended to situations in which each transmitter has additional finite-rate partial CSI on the link quality of others.

Keywords:

• Capacity Region
• Distributed CSI
• Distributed rate allocation
• Fading Statistics
• Multiple-Access Channel
• Power control

Acknowledgements

The authors thank Urs Niesen for providing leads to the usage of single-user decoding strategies. The presentation also benefited considerably from discussions with Sreejith Sreekumar and Yash Deshpande. This paper was presented in part at the IEEE Information Theory workshop, ITW’2011 Paraty, Brazil and at the International Symposium on Information Theory and Applications, ISITA’2012 Hawaii.

Notes

1. Sometimes the transmit-power of users may not be commensurate, however we can choose a slightly lower power level for some of the users, with negligible loss of performance.

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Additional information

Funding

This work was supported in part by Bharti Centre for Communication at IIT Bombay, DST India [grant SB/S3/EECE/077/2013], India-UK Advance Technology Center of Excellence in Next Generation Networks and Services- Phase 2.

Notes on contributors

Krishnamoorthy Iyer

Krishnamoorthy Iyer obtained his Bachelor of Technology degree in engineering physics from the Indian Institute of Technology Bombay, India in 1998. Since January 2009, he has been a doctoral candidate in the Department of Electrical Engineering. His current research focus is on network information theory and its applications to wireless networks and information theoretic security. He is also interested in applying information theory to neuroscience, specifically to the study of neural codes and computation. A salsero, he divides his free time between practising Yoga and reading omnivorously.

E-mail: [email protected]

Sibi Raj B. Pillai

Sibi Raj B Pillai is with the Department of Electrical Engineering at IIT Bombay, where he joined as an assistant professor in 2009. He obtained his doctoral degree in computer science and communication systems from EPFL, Switzerland in July 2007. From October 2007 to April 2009, he was a research fellow at the University of Melbourne. His research interests are in network information theory, resource allocation problems, application of feedback, cross-layer scheduling, etc. He handles the Information Systems and Radios Lab at IIT Bombay, which specializes in developing software radio applications for wireless communications. Dr S. R. B. Pillai has received the 2009 ACorn-NICTA Australian early career researcher award for excellence in communication theory.

E-mail: [email protected]

Bikash K. Dey

Bikash Kumar Dey received his BE degree in electronics and telecommunication engineering from Bengal Engineering College, Howrah in 1996. He received his ME degree in signal processing from the Indian Institute of Science, Bangalore, India in 1999 and received his PhD in electrical communication engineering from the Indian Institute of Science in 2003. From August 1996 to June 1997, he worked at Wipro Infotech Global R&D. In February 2003, he joined Hellosoft India Pvt. Ltd. as a technical member. In June 2003, he joined the International Institute of Information Technology, Hyderabad, India, as an assistant professor. He joined the Department of Electrical Engineering of IIT-Bombay in May 2005 as an assistant professor, where he currently is an associate professor. His research interests include error correcting codes and wireless communications. Dr Dey was awarded the Prof. I. S. N. Murthy Medal from IISc as the best ME student in the Department of Electrical Communication Engineering and Electrical Engineering for 1998–1999 and Alumni Medal for best PhD thesis in the division of electrical sciences for 2003–2004.

E-mail: [email protected]