Showing papers by "Dinesh Rajan published in 2009"

Capacity bounds of half-duplex gaussian cooperative interference channel

Abstract: In this paper, we study the capacity region of a two user Gaussian interference channel with half duplex node constraints. We develop an achievable region and outer bound for the case when the system allows either transmitter or receiver cooperation. We show that by using our transmitter cooperation scheme, there is significant capacity improvement compared to the previous results [1], [2], especially when the cooperation link is strong. Further, if the cooperation channel gain is infinity, both our transmitter and receiver cooperation rates achieve their respective outer bound. It is also shown that transmitter cooperation provides larger achievable region than receiver cooperation under the same channel and power conditions.

Achievable Rate of Gaussian Cognitive Z-Interference Channel with Partial Side Information

Abstract: In this paper, we compute an achievable rate of a Gaussian Z-interference channel as shown in Fig. 1, when transmit node C has causal, imperfect cognitive knowledge of the signal sent by transmit node A. This achievable rate is derived using a two-phase transmission scheme in which node C uses a combination of a linear minimum mean square error (LMMSE) estimator and dirty paper code and node D employs a combination of LMMSE estimator and partial interference canceler. Numerical results indicate that the achievable rate of the Gaussian Z-interference channel increases significantly with cognition under certain channel conditions. We also derive an upper bound on the capacity of this channel with cognition and quantify the channel conditions under which the proposed achievable scheme equals the upper bound.

Multi-channel, 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.

A monolithic one-sample/bit partial-response maximum likelihood SiGe receiver for electronic dispersion compensation of 10.7Gb/s fiber links

Abstract: Combining, for the first time, a 1-sample/bit monolithic PRML silicon with standard MZM modulators and PIN receivers, we experimentally demonstrate error-free transmission (with standard G709 FEC) over a 400-Km uncompensated standard single-mode fiber link.

Capacity Bounds of Half-Duplex Gaussian Cooperative Interference Channel

Abstract: In this paper, we investigate the half-duplex cooperative communication scheme of a two user Gaussian interference channel. We develop achievable region and outer bound for the case when the system allow either transmitter or receiver cooperation. We show that by using our transmitter cooperation scheme, there is significant capacity improvement compare to the previous results, especially when the cooperation link is strong. Further, if the cooperation channel gain is infinity, both our transmitter and receiver cooperation rates achieve their respective outer bound. It is also shown that transmitter cooperation provides larger achievable region than receiver cooperation under the same channel and power conditions.

Channel capacity and modeling of optical fiber communications

Abstract: We use the method of multiple scales borrowed from perturbation theory to derive a new time-domain transfer function of the nonlinear fiber-optic wave-division multiplexing (WDM) communications channel. The obtained channel response, derived from the nonlinear Schrodinger equation is shown to be equivalent to the multi-path fading frequency selective channel encountered in wireless links. In the linear regime, the channel response is shown to be equivalent to a standard intersymbol interference (ISI) channel and is used to derive new bounds on the capacity of the dispersive optical fiber channel.

Noisy DPC and Application to a Cognitive Channel

Abstract: In this paper, we first consider a channel that is contaminated by two independent Gaussian noises $S ~ N(0,Q)$ and $Z_0 ~ N(0,N_0)$ The capacity of this channel is computed when independent noisy versions of $S$ are known to the transmitter and/or receiver It is shown that the channel capacity is greater then the capacity when $S$ is completely unknown, but is less then the capacity when $S$ is perfectly known at the transmitter or receiver For example, if there is one noisy version of $S$ known at the transmitter only, the capacity is $05log(1+P/(Q(N_1/(Q+N_1))+N_0))$, where $P$ is the input power constraint and $N_1$ is the power of the noise corrupting $S$ We then consider a Gaussian cognitive interference channel (IC) and propose a causal noisy dirty paper coding (DPC) strategy We compute the achievable region using this noisy DPC strategy and quantify the regions when it achieves the upper bound on the rate