Search results for: A. Grami
article
chapter
One future opportunity for satellites is to extend the reach of the planned “information superhighway” to areas not served or underserved by terrestrial networks. Future satcom systems, such as the proposed Canadian advanced satcom system, the Hughes Spaceway system in the U.S., and the global Teledesic system all aim to provide digital wideband multimedia communications to off-net users. To that...
chapter
Designing a comprehensive curriculum for information system engineering (ISE) that accounts for the needs and expectations of the students, the current trends and advances in the field, and the skills required by the job market is an extremely demanding task. The curriculum must balance the highest academic standards and integrity against the emerging expectations of the market. Here, we identify...
article
IEEE Transactions on Signal Processing > 2010 > 58 > 3-1 > 1238 - 1250
In this paper, we consider a relay network which consists of two single-antenna transceivers and nr single-antenna relay nodes. Considering a two time slot two-way relaying scheme, each relay adjusts the phase and the amplitude of the mixture signal it receives from the two transceivers during the first time slot, by multiplying it with a complex beamforming coefficient. Then each relay transmits...
article
IEEE Transactions on Signal Processing > 2010 > 58 > 9 > 4966 - 4972
In this correspondence, we study the problem of joint receive and transmit beamforming for a wireless network consisting of a transmitter, a receiver, and a relay node. The relay node is equipped with multiple antennas while the transmitter and the receiver each uses only one antenna. Our communication scheme consists of two phases: first the transmitter sends the information symbols to the relay...
chapter
We consider a wireless network consisting of a single-antenna transmitter, a single-antenna receiver, and a multi-antenna relay node. For such a network, we introduce the novel approach of general rank beamforming. In this approach, the relay multiplies the vector of its received signals by a general-rank complex matrix to obtain a new vector. Each entry of this new vector is then transmitted on one...
chapter
We consider a relay network which consists of two transceivers and r relay nodes. Assuming that the transceivers and the relays are all equipped with single antennas, we devise a two-way amplify-and-phase-adjust relaying scheme. In this scheme, each relay multiplies its received signal by a complex weight and transmits the so-obtained signal thereby participating in a distributed beamforming process...
chapter
We consider a relay network which consists of two transceivers and r relay nodes. We study a half-duplex two-way relaying scheme. First, the two transceivers transmit their information symbols simultaneously and the relays receive a noisy mixture of the two transceiver signals. Then each relay adjusts the phase and the amplitude of its received signal by multiplying it with a complex beamforming coefficient...
chapter
In this paper, we use a 4times4 MIMO testbed to investigate the experimental performance of the blind channel estimation technique presented in (Shahbazpanahi et al., 2005). The operating frequency throughout all experiments was selected to be 2.47 GHz and the transmission bandwidth was 20 MHz. Our experimental results show that the performance of the blind technique can be very close to that of non-blind...
chapter
The problem of distributed beamforming is considered for a network which consists of a transmitter, a receiver, and r relay nodes. Assuming that the second order statistics of the channel coefficients are available, we design a distributed beamforming technique via maximization of the receiver signal-to-noise ratio (SNR) subject to individual relay power constraints. We show that using semi-definite...
chapter
Designing a satellite system presents many challenges, for it is a non-linear optimization problem. Optimization is achieved to meet the satellite's orbital slot, spectrum, mass, real estate, power, and complexity constraints, while accommodating the system's cost, coverage, capacity, networking, performance, and user requirements. In this paper, through optimization of satellite resources and service...
article
IEEE Transactions on Signal Processing > 2008 > 56 > 9 > 4306 - 4316
In this paper, the problem of distributed beamforming is considered for a wireless network which consists of a transmitter, a receiver, and relay nodes. For such a network, assuming that the second-order statistics of the channel coefficients are available, we study two different beamforming design approaches. As the first approach, we design the beamformer through minimization of the total transmit...
chapter
Satellites are uniquely qualified to ensure universal broadband access to the infrastructure, for the cost of access in all parts of Canada and US by broadband terrestrial systems- including telephone lines, coaxial cables, power-lines, and fixed wireless networks-would be prohibitive. Major advances in satellite technology on the one hand and market demand for small, low-cost high-speed user terminals...
chapter
A class of Nyquist pulses with a monomial roll-off is proposed. Using the measures of closeness to Nyquist-II criterion (eye-width) and robustness to sampling phase jitter, their performances are assessed. It is shown that these pulses generally outperform the pulses with cosine or linear roll-offs.
chapter
Low population density in many areas and harsh terrain in certain regions of North America pose economic and logistical barriers to the expansion of advanced terrestrial facilities and technologies required to support broadband services. Noting a quintessential role for communications satellite systems is to extend the reach of the Internet and interactive multimedia services to areas un-served or...
chapter
A class of Nyquist-I pulse shaping filters are introduced and their performances are assessed, using the measures of closeness to Nyquist-II criterion (eye width) and robustness to sampling phase jitter. It is shown that these filters generally outperform the common raised-cosine filters
chapter
In this paper, various aspects of satellite communications systems are discussed. First, the new satellite services and their operating frequency bands are identified. This is followed by the lessons learned from the recent satellite system ventures. Also, various enabling technologies, required to introduce an array of satellite services, are examined, and some innovative satellite design considerations...
