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Kiran Kuchi

Bio: Kiran Kuchi is an academic researcher from Indian Institute of Technology, Hyderabad. The author has contributed to research in topics: Telecommunications link & MIMO. The author has an hindex of 23, co-authored 104 publications receiving 1450 citations. Previous affiliations of Kiran Kuchi include Motorola & University of Texas at Arlington.


Papers
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Patent
Kiran Kuchi1, Yrjo Kaipanen1, Markku Kuusela1, Olav Trikkonen1, Ari Hottinen1 
26 Mar 2002
TL;DR: In this paper, the authors proposed a method and apparatus for phase hopping and space-time coding signals for transmission on multiple antennas, where phase hopping on the symbols within the N×N′ space time block code was used to allow transmission of the space time blocks code on a number of diversity antennas greater than N′.
Abstract: The present invention presents a method and apparatus for phase hopping and space-time coding signals for transmission on multiple antennas. The method and apparatus provides expansion of a N×N′ space time block code to a M×M′ space time block code, where M>N, by using phase hopping on the symbols within the N×N′ space time block code to allow transmission of the space time block code on a number of diversity antennas greater than N′. A result of M antenna diversity may be achieved for M transmit antennas.

136 citations

Patent
22 Feb 1999
TL;DR: In this article, the authors propose a method for wireless data communication between a base station and a subscriber unit in a wireless communication system, where groups of symbols of an input data stream are commutated to produce a plurality of data streams.
Abstract: In a method for wireless data communication between a base station and a subscriber unit in a wireless communication system, groups of symbols of an input data stream are commutated to produce a plurality of commutated data streams. The plurality of commutated data streams are then transformed to produce a plurality of transformed data streams. Next, each transformed data stream is spread with a selected one of a plurality of spreading codes to produce a plurality of antenna signals. Finally, each of the plurality of antenna signals is transmitted using a selected one of a plurality of spaced apart antennas, wherein the plurality of spaced apart antennas are spaced apart to provide transmit diversity. In one embodiment, the transform is a space-time transform.

111 citations

Patent
Kiran Kuchi1, Jyri Hamalainen1
29 Mar 2001
TL;DR: In this article, a method and apparatus for space-time coding signals for transmission on multiple antennas was proposed, where a received input symbol stream is transformed using a predefined transform and transmitted on a first set of N antennas.
Abstract: A method and apparatus for space-time coding signals for transmission on multiple antennas. A A method and apparatus for space-time coding signals for transmission on multiple antennas. A received input symbol stream is transformed using a predefined transform and transmitted on a first set of N antennas. The same input symbol stream is then offset by M symbol periods to generate an offset input symbol stream. The offset input symbol stream is then transformed using the predefined transform and transmitted on a second set of N antennas. A third through Xth set of N antennas may be utilized for transmission by successively offsetting the offset input symbol stream by an additional M symbol periods for each additional set of N antennas used, before performing the transform and transmitting on the additional set of N antennas.

85 citations

Proceedings ArticleDOI
16 May 1999
TL;DR: In this paper, the performance benefits of open loop and closed loop transmit diversity methods for CDMA are compared. But the performance of OTT and TXAA is not compared. And the performance performance of open-loop and closed-loop OTT is not evaluated.
Abstract: Code division multiple access (CDMA) is a common access scheme among all major proposals for third generation cellular standards. The objective of this paper is to show the performance benefits of open loop (which do not adapt transmission based on the channel to the mobile) and closed loop (which do adapt based on the channel to the mobile) transmit diversity methods for CDMA. We examine orthogonal transmit diversity (OTD) (an open loop method), and transmit adaptive arrays (TXAA) (a closed loop method).

70 citations

Proceedings ArticleDOI
19 Sep 1999
TL;DR: The link performance of transmit diversity (TD) schemes for third generation CDMA systems is analyzed and an interleaving approach is shown that works for various TD schemes as well as non-TD.
Abstract: The link performance of transmit diversity (TD) schemes for third generation CDMA systems is analyzed. Orthogonal transmit diversity (OTD) and space-time transmit diversity (STTD) are compared. It is shown that the link performances of OTD and STTD are nearly the same. However, STTD requires additional receiver processing, and STTD is not directly extendable to more than 2 antennas, because rate one space-time block codes do not exist for greater than 2 antennas. Also, an interleaving approach is shown that works for various TD schemes as well as non-TD.

64 citations


Cited by
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01 Jan 2013
TL;DR: From the experience of several industrial trials on smart grid with communication infrastructures, it is expected that the traditional carbon fuel based power plants can cooperate with emerging distributed renewable energy such as wind, solar, etc, to reduce the carbon fuel consumption and consequent green house gas such as carbon dioxide emission.
Abstract: A communication infrastructure is an essential part to the success of the emerging smart grid. A scalable and pervasive communication infrastructure is crucial in both construction and operation of a smart grid. In this paper, we present the background and motivation of communication infrastructures in smart grid systems. We also summarize major requirements that smart grid communications must meet. From the experience of several industrial trials on smart grid with communication infrastructures, we expect that the traditional carbon fuel based power plants can cooperate with emerging distributed renewable energy such as wind, solar, etc, to reduce the carbon fuel consumption and consequent green house gas such as carbon dioxide emission. The consumers can minimize their expense on energy by adjusting their intelligent home appliance operations to avoid the peak hours and utilize the renewable energy instead. We further explore the challenges for a communication infrastructure as the part of a complex smart grid system. Since a smart grid system might have over millions of consumers and devices, the demand of its reliability and security is extremely critical. Through a communication infrastructure, a smart grid can improve power reliability and quality to eliminate electricity blackout. Security is a challenging issue since the on-going smart grid systems facing increasing vulnerabilities as more and more automation, remote monitoring/controlling and supervision entities are interconnected.

1,036 citations

Journal ArticleDOI
TL;DR: This work proposes a general approach to differential modulation for multiple transmit antennas based on group codes, which can be applied to any number of transmit and receive antennas, and any signal constellation, and can be demodulated with or without channel estimates.
Abstract: Space-time coding and modulation exploit the presence of multiple transmit antennas to improve the performance on multipath radio channels Thus far, most work on space-time coding has assumed that perfect channel estimates are available at the receiver In certain situations, however, it may be difficult or costly to estimate the channel accurately, in which case it is natural to consider the design of modulation techniques that do not require channel estimates at the transmitter or receiver We propose a general approach to differential modulation for multiple transmit antennas based on group codes This approach ran be applied to any number of transmit and receive antennas, and any signal constellation We also derive low-complexity differential receivers, error bounds, and modulator design criteria, which we use to construct optimal differential modulation schemes for two transmit antennas These schemes can be demodulated with or without channel estimates This permits the receiver to exploit channel estimates when they are available The performance degrades by approximately 3 dB when estimates are not available

944 citations

Patent
10 Jun 2001
TL;DR: In this paper, the authors exploit the substantive reciprocity of internode channel responses through dynamic, adaptive modification of receive and transmit weights, enabling locally enabled global optimization of a multipoint, wireless electromagnetic communications network of communication nodes.
Abstract: Exploiting the substantive reciprocity of internode channel responses through dynamic, adaptive modification of receive and transmit weights, enables locally enabled global optimization of a multipoint, wireless electromagnetic communications network of communication nodes. Each diversity-channel-capable node uses computationally efficient exploitation of pilot tone data and diversity-adaptive signal processing of the weightings and the signal to further convey optimization and channel information which promote local and thereby network-global efficiency. The preferred embodiment performs complex digital signal manipulation that includes a linear combining and linear distribution of the transmit and receive weights, the generation of piloting signals containing origination and destination node information, as well as interference-avoiding pseudorandom delay timing, and both symbol and multitione encoding, to gain the benefit of substantive orthogonality at the physical level without requiring actual substantive orthogonality at the physical level.

634 citations

Proceedings ArticleDOI
T.K.Y. Lo1
06 Jun 1999
TL;DR: The analysis shows that the average overall SNR is proportional to the cross-correlation between channel vectors and that error probability decreases inversely with the (L/spl times/K)th power of the average SNR.
Abstract: This paper presents the concept, principles, and analysis of maximum ratio transmission for wireless communications where multiple antennas are used for both transmission and reception. The principles and analysis are applicable to general cases, including maximum ratio combining. Simulation results agree with the analysis. The analysis shows that the average overall SNR is proportional to the cross-correlation between channel vectors and that error probability decreases inversely with the (L/spl times/K)th power of the average SNR.

609 citations

Proceedings ArticleDOI
06 Sep 2000
TL;DR: A linear decoding based on iterative interference cancellation between parts of the code approaches the maximal likelihood decoding performance.
Abstract: We propose a full rate space-time block code for 3+ Tx antennas. The code is chosen to minimize the non-orthonormality that arises from increasing the rate above the maximum allowed by orthogonality. A linear decoding based on iterative interference cancellation between parts of the code approaches the maximal likelihood decoding performance.

578 citations