Showing papers by "Dinesh Rajan published in 2010"

Wireless Network Design: Optimization Models and Solution Procedures

Abstract: This booksurveys state-of-the-art optimization modeling for design, analysis, and management of wireless networks, such as cellular and wireless local area networks (LANs), and the services they deliver. The past two decades have seen a tremendous growth in the deployment and use of wireless networks. The current-generation wireless systems can provide mobile users with high-speed data services at rates substantially higher than those of the previous generation. As a result, the demand for mobile information services with high reliability, fast response times, and ubiquitous connectivity continues to increase rapidly. The optimization of system performance has become critically important both in terms of practical utility and commercial viability, and presents a rich area for research. In the editors' previous work on traditional wired networks, we have observed that designing low cost, survivable telecommunication networks involves extremely complicated processes. Commercial products available to help with this task typically have been based on simulation and/or proprietary heuristics. As demonstrated in this book, however, mathematical programming deserves a prominent place in the designer's toolkit. Convenient modeling languages and powerful optimization solvers have greatly facilitated the implementation of mathematical programming theory into the practice of commercial network design. These points are equally relevant and applicable in todays world of wireless network technology and design. But there are new issues as well: many wireless network design decisions, such as routing and facility/element location, must be dealt with in innovative ways that are unique and distinct from wired (fiber optic) networks. The book specifically treats the recent research and the use of modeling languages and network optimization techniques that are playing particularly important and distinctive roles in the wireless domain.

Capacity Bounds for a Cognitive MIMO Gaussian Z-Interference Channel

Abstract: In this paper, we compute an achievable rate of a multiple-input-multiple-output (MIMO) Gaussian Z-interference channel (ZIC), as shown in Fig 1, when transmit node C has imperfect cognitive knowledge of the signal sent by transmit node A First, we compute the capacity of this channel, assuming noncausal but noisy knowledge at node C of node A's signal We then compute the achievable rate for a causal cognitive strategy: This achievable rate is derived using a two-phase transmission scheme, in which node C uses a combination of a linear MMSE (LMMSE) estimator and a dirty-paper code, and node D employs a combination of an LMMSE estimator and a partial interference canceler The achievable rate is studied in two different cases: 1 Node C operates in full-duplex mode, and 2 node C operates in half-duplex mode To quantify the performance of the proposed strategy, we compute simple lower and upper bounds on the capacity of this channel Similar to an interference channel, the achievable rate of the cognitive ZIC nonmonotonically varies with the interference Specifically, the achievable rate first decreases with the channel gain between nodes A and D and then begins to increase beyond a certain threshold The difference in the achievable rate between full- and half-duplex transmissions is also numerically evaluated

Super Resolution results in PANOPTES, an adaptive multi-aperture folded architecture

Abstract: We present experimental results of digital super resolution (DSR) techniques on low resolution data collected using PANOPTES, a multi-aperture miniature folded imaging architecture. The flat form factor of PANOPTES architecture results in an optical system that is heavily blurred with space variant PSF which makes super resolution challenging. We also introduce a new DSR method called SRUM (Super-Resolution with Unsharpenning Mask) which can efficiently highlight edges by embedding an unsharpenning mask to the cost function. This has much better effect than just applying the mask after all iterations as a post-processing step.

Multichannel, agile, computationally enhanced camera based on the PANOPTES architecture

Abstract: A multi-channel, agile, computationally enhanced camera based on the PANOPTES architecture is presented. Details of camera operational concepts are outlined. Preliminary image acquisition results and an example of super-resolution enhancement of captured data are given.

Half-duplex gaussian interference channel with transmitter and receiver cooperation

Abstract: We propose an achievable region and capacity outer bound for half-duplex Gaussian interference channel with both transmitter (TX) and receiver (RX) cooperation. We show the significant improvement in achievable region compared to either TX or RX cooperation alone. Further, we quantify the sum rate increase with respect to the cooperation channel gain.