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Sun L.,NEC Laboratories | Li P.,Hong Kong University of Science and Technology | McKay M.R.,Hong Kong University of Science and Technology | Murch R.D.,Hong Kong University of Science and Technology
IEEE Transactions on Signal Processing | Year: 2012

This paper deals with the fundamental limit of capacity for MIMO wireless systems with antenna mutual coupling. Motivated by practical considerations, the capacity-achieving precoder is found by maximizing the capacity subject to two separate power constraints; namely, a constraint on the available power at the transmitter which is imposed on a per-amplifier basis, and a constraint on the allowable radiated power. These two separate constraints occur because MIMO antenna systems are usually unable to use a perfect conjugate multiport impedance match in practice and therefore MIMO systems with mutual coupling usually do not radiate all of the power input or available to them. Assuming that perfect channel state information is available to both the transmitter and receiver, we first derive sufficient conditions on the power constraints, in terms of the mutual coupling, under which the dual-constraint problem reduces to effectively a single-constraint problem. This greatly simplifies the optimization problem in some cases. For the more general case where both constraints are relevant, we present an efficient suboptimal algorithm by first relaxing the per-amplifier power constraint to a sum power constraint and then solving the dual-constraint problem based on dynamic water-filling and mode-dropping. Finally, we investigate the optimal precoder design at high signal to noise ratios, and provide stronger theoretical results in this regime. Numerical results are provided to demonstrate the effectiveness of our technique when dual power constraints are important to consider. © 2011 IEEE.


Yuan F.,Beihang University | Yang C.,Beihang University | Wang G.,NEC Laboratories | Lei M.,NEC Laboratories
IEEE Transactions on Wireless Communications | Year: 2013

In this paper, a channel direction information (CDI) feedback strategy is proposed to assist coordinated multi-point beamforming (CoMP-CB) between a macro base station (MBS) and multiple pico BSs (PBSs) in heterogeneous networks, where the numbers of bits for feedback are adaptive to the average channel gains of multiple users. To maximize the average sum rate achieved by the users with given feedback resource, we optimize the overall number of feedback bits for each user and the codebook sizes for quantizing the per-cell CDIs of each user. To provide feasible feedback scheme for practice use, a low complexity two-step solution is developed from deriving the lower bounds of the per-user average rate. In the first step, we optimize the number of overall feedback bits for each user, which provides a tradeoff between the accuracy of CDI quantization and the reliability of feedback transmission. In the second step, we optimize the bit allocation for quantizing the per-cell CDIs, which accommodates the difference in transmit powers and antennas of the MBS and PBSs and in the channels of macro and pico cells. Two adaptive feedback schemes are developed from two lower bounds. By characterizing the degree of freedom (DoF) achieved by each user, we show that the systems using the proposed adaptive feedback schemes are no longer interference-limited. The maximum per-user DoFs achieved by the proposed schemes depend on the per-antenna feedback resource constraint for each user. Simulation results show significant performance gain of the proposed scheme over NonCoMP and CoMP-CB with fixed codebook size. © 2002-2012 IEEE.


Tang X.,Link A Media Devices | Wang S.,NEC Laboratories
IEEE Transactions on Computers | Year: 2010

A self-diagnosis circuit that can be used for built-in self-repair is proposed. The circuit under diagnosis is assumed to be composed of a large number of field repairable units (FRUs), which can be replaced with spares when they are found to be defective. Since the proposed self-diagnosis circuit is implemented on the chip, responses that are scanned out of scan chains are compressed by the group compactor, the space compression circuit, and finally, the time compression circuit to reduce the volume of test response data. Both the space and time compression circuits implement a Reed-Solomon code. Unlike prior work, in the proposed technique, responses of all FRUs are observed at the same time to reduce diagnosis time. The proposed diagnosis circuit can locate up to l defective FRUs. We propose a novel space compression circuit that reduces hardware overhead by exploiting the frequency difference of the scan shift clock and the system clock and by combining scan cells into groups of size r. When the size of constituent multiple-input signature register (MISR) is m, the total number of signatures to be stored for the fault-free signature is 2lmB bits, where 1\le B \le m. The experimental results show that the proposed diagnosis circuit that can locate up to four defective FRUs in the same test session can be implemented with less than one percent of hardware overhead for a large industrial design. Hardware overhead for the diagnosis circuit is lower for large CUDs. © 2006 IEEE.


News Article | November 30, 2016
Site: www.prweb.com

Tran & Associates, a Silicon Valley intellectual property law firm, recently released TrustyTrademark™, a program that helps businesses register and protect their trademarks. “TrustyTrademark allows a business to manage all its trademark filings in one place,” said Bao Tran, principal attorney at Tran & Associates and founder of PowerPatent Inc. “Many small businesses don’t realize that their name and products need to be protected, and once they are registered using TrustyTrademark, their brand is protected.” Tran & Associates’s TrustyTrademark is different than other trademark registries in that, like a GPS providing guidance to a driver, TrustyTrademark guides a business owner in preparing and filing the trademark application, and upon request, a trademark specialist can review and complete the trademark application for the business. TrustyTrademark allows a business to obtain trademark-pending status in a cost-effective manner through a trademark registration with the United States Patent and Trademark Office. “In approximately 6-12 months, a trademark attorney from the U.S. Patent and Trademark Office will review the file and ensure there are no conflicts,” said Tran. “If there are no conflicts, they will grant you a trademark, and your brand will be protected nationwide with a federal trademark registration.” Mr. H. Nguyen, founder of Team-M Taekwondo, an elite taekwondo demonstration team that started in San Jose, CA, in 2004, received allowance of its application for the mark M-TEAM™ using TrustyTrademark in less than six months from filing. “TrustyTrademark has been a great help for our organization in getting our trademark request processed,” said Nguyen, whose Team-M’s performances and dedication are inspirational to taekwondo practitioners worldwide. “We were totally new to the process, and the staff from TrustyTrademark were professional, patient, and helpful throughout every step of the way.” TrustyTrademark also recently received approval, under the Intuit QuickBooks™ online developer program, for the TrustyTrademark QB app for the Intuit QuickBooks apps marketplace. “This integration with QuickBooks Online will help make trademarks more accessible to small businesses using QuickBooks that might think they can’t afford the cost of protecting their brands through the trademark system,” concluded Tran. About Tran & Associates Tran & Associates is the premier intellectual property law firm headquartered in Silicon Valley. The firm protected IPs for many companies during their formative years, such as Shutterfly, Zetta, Reflect Scientific, NEC Laboratories America, Inc., and numerous start-ups from inception to venture-funded companies. PowerPatent is a privately held software applications company headquartered in Silicon Valley. Its products are designed and developed by a team of legal, software, user experience and web design professionals. Its mission is to democratize the intellectual property (IP) ecosystem. For more information, please call (408) 528-7490, or visit http://www.powerpatent.com. About the NALA™ The NALA offers small and medium-sized businesses effective ways to reach customers through new media. As a single-agency source, the NALA helps businesses flourish in their local community. The NALA’s mission is to promote a business’ relevant and newsworthy events and achievements, both online and through traditional media. For media inquiries, please call 805.650.6121, ext. 361.


Foschini L.,University of Bologna | Taleb T.,NEC Laboratories | Corradi A.,University of Bologna | Bottazzi D.,Laboratori Guglielmo Marconi
IEEE Communications Magazine | Year: 2011

Machine-to-machine communications are gaining tremendous interest from mobile network operators, equipment vendors, device manufacturers, as well as research and standardization bodies. Indeed, M2M is a promising technology for the development of Internet of Things communications platforms, with high potential to enable a wide range of applications in different domains. However, providing suitable answers to the issues stemming from IoT platform design requires middleware-level solutions to enable seamless interoperability between M2M-based applications and existing Internetbased services. To the best of our knowledge, available proposals in the field are still immature and tend to be proof of concept prototypes that address specific issues stemming from IoT domains. This article starts from a different perspective and aims at investigating the possibility of implementing M2M solutions on top of currently available, mature, production-level solutions. In this vein, we here present and discuss the design and implementation of an M2M application in the field of road traffic management that integrates, for the sake of efficiency, with a broad IMS-based service infrastructure. © 2011 IEEE.


Choi W.,NEC Laboratories | Savarese S.,Stanford University
IEEE Transactions on Pattern Analysis and Machine Intelligence | Year: 2014

This paper presents a principled framework for analyzing collective activities at different levels of semantic granularity from videos. Our framework is capable of jointly tracking multiple individuals, recognizing activities performed by individuals in isolation (i.e., atomic activities such as walking or standing), recognizing the interactions between pairs of individuals (i.e., interaction activities) as well as understanding the activities of group of individuals (i.e., collective activities). A key property of our work is that it can coherently combine bottom-up information stemming from detections or fragments of tracks (or tracklets) with top-down evidence. Top-down evidence is provided by a newly proposed descriptor that captures the coherent behavior of groups of individuals in a spatial-temporal neighborhood of the sequence. Top-down evidence provides contextual information for establishing accurate associations between detections or tracklets across frames and, thus, for obtaining more robust tracking results. Bottom-up evidence percolates upwards so as to automatically infer collective activity labels. Experimental results on two challenging data sets demonstrate our theoretical claims and indicate that our model achieves enhances tracking results and the best collective classification results to date. © 2013 IEEE.


Yi S.,NEC Laboratories | Lei M.,NEC Laboratories
IEEE Wireless Communications and Networking Conference, WCNC | Year: 2012

In 3GPP LTE-Advanced, relay is considered as an important means for extending cell coverage and improving capacity. Backhaul resource allocation needs to be carefully designed to achieve the performance advantage of relay. In this paper, we propose a two-step backhaul resource allocation scheme for an inband relaying system based on relay buffer level. The resource assignment to relays meets the actual traffic demand, takes into account the link quality of the backhaul link and the access link, and the resource partitioning between relays and macro UEs is then optimized. Our evaluations show that the proposed framework can improve the cell average and cell-edge user performance, for different deployment scenarios. This approach has very low complexity in implementation and the revision to current standard is very minimal. © 2012 IEEE.


Jiang L.,NEC Laboratories | Lei M.,NEC Laboratories
IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC | Year: 2012

This paper investigates the channel quality indicator (CQI) adjustment for enhanced inter-cell interference coordination (eICIC) scheme in heterogeneous networks (HetNets). In the eICIC scheme, the user equipments (UEs) in the protected cells (either small or macro cells) experience different interference levels due to the almost blank subframes (ABSs) configured at aggressor eNBs (macro or small cell eNBs). In order to reduce the signaling overhead of the CQI report for both of the subframe types, we propose to adjust the reported CQIs of the UEs in protected cells by estimating the interference from the aggressor eNBs. The CQI adjustment requirement will be determined by comparing the types of subframes where the CQI is measured and used. The interference can be estimated either with UE position information or without UE position information. The latter one is applicable only in the scenario where macro eNBs are aggressors. Simulation results show that the CQI adjustment can improve the UE performance and achieve close gain compared with the two-CQI report method. © 2012 IEEE.


Jiang L.,NEC Laboratories | Lei M.,NEC Laboratories
IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC | Year: 2012

This paper proposes a resource allocation scheme for enhanced inter-cell interference coordination (eICIC) in heterogeneous networks. In the eICIC system, the macro eNBs will stop data transmission in almost blank subframes (ABSs), where the UEs in small cells can be protected. The proposed scheme takes into account both the number of the ABSs configured at the macro eNBs and the UE partition scheme in small cells to achieve the performance balance between the macro cells and the small cells. Simulation results show that the proposed scheme outperforms the existing methods regardless of the configured ABS pattern and the UE partition scheme. The performance gain in the cell spectrum efficiency is achieved by slightly sacrificing the medium UEs with medium values of signal to interference plus noise ratio (SINRs) to further improve the best UEs with high SINRs without degradation of the edge UEs. © 2012 IEEE.


Sun L.,NEC Laboratories | Lei M.,NEC Laboratories
IEEE Transactions on Wireless Communications | Year: 2013

This paper considers the implementation of Tomlinson-Harashima (TH) precoding for multiuser MIMO systems based on quantized channel state information (CSI) at the transmitter side. Compared with the results in , our scheme applies to more general system setting where the number of users in the system can be less than or equal to the number of transmit antennas. We also study the achievable average sum rate of the proposed quantized CSI-based TH precoding scheme. The expressions of the upper bounds on both the average sum rate of the systems with quantized CSI and the mean loss in average sum rate due to CSI quantization are derived. We also present some numerical results. The results show that the nonlinear TH precoding can achieve much better performance than that of linear zero-forcing precoding for both perfect CSI and quantized CSI cases. In addition, our derived upper bound on the mean rate loss for TH precoding converges to the true rate loss faster than that of zero-forcing precoding obtained in as the number of feedback bits becomes large. Both the analytical and numerical results show that nonlinear precoding suffers from imperfect CSI more than linear precoding does. © 2002-2012 IEEE.

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