Irma Zakia

Performance comparisons of adaptive MVDR and received LS beamforming on the downlink time varying channel of HAP system

We consider the performance comparisons of adaptive Minimum Variance Distortionless Response (MVDR) and received Least Squares (LS) beamforming on the downlink channel from High Altitude Platform (HAP) to high speed train. The channel, as modeled in CAPANINA project, is considered as time varying rician and flat fading process. Since the rician factor is moderate to high, adaptive MVDR beamforming is attractive in compensating for the rician fading channel. Due to the constraint in the cost function, MVDR beamforming neglects useful received signal particularly in the lower rician factors, hence, mismatch occurs. By implementing the LS beamforming, the receiver is able to adapt better to a more rayleigh fading channel case. The comparisons of the considered beamforming algorithms are given in terms of Mean Square Error (MSE) of beamforming weight tracking and Bit Error Rate (BER).

Coverage and capacity trade-off using admission and power controlled CDMA system for wireless internet services in rural environments

In this paper the coverage and capacity of CDMA system is evaluated using admission and power control to serve for low to medium speed internet services, such as digital TV or film/video streaming in rural areas. One of the unique characteristics of CDMA system is that it is possible to trade off between capacity and its coverage, called the cell-breathing. Open loop and closed loop power control can be used to increase the capacity of CDMA system; while admission control can be applied to trade-off between its capacity and the coverage. Computer simulation was conducted to evaluate the power control performance in Rayleigh fading channel. Then semi-analytical evaluation was performed to obtain the coverage-capacity trade-off. The result shows that the capacity of CDMA systems increases when power control was employed. Numerical and semi analytical evaluation show that CDMA coverage and capacity can be traded-off to meet various demand of traffic capacity and cell coverage in rural environments.

A simulation study of least-squares received beamforming on HAP frequency-selective channel

This paper explores the impact of slightly frequencyselective Rician fading channel on the performance of leastsquares received beamforming. This channel type is encountered in the communications from high-altitude platform (HAP) to high-speed train (HST) in urban area and at Ka-band operating frequency. The system performance in terms of mean-square error (MSE) and bit error rate (BER) for different scenarios of Direction of Arrival (DOA) are evaluated by Monte Carlo simulation.

Accelerating internet penetration to rural areas: A government-sponsored internet-kiosks deployment project in Garut Regency, West Java of Indonesia

Internet penetration in developing countries depend on a variety of factors, including the Gross Domestic Product (GDP), the density of telephone connections, and the density of personal computer users. Internet kiosks have been deployed in 21 rural ditrict areas of Garut Regency to facilitate internet access for local/district government as well as for the community who have no access to internet Each district was equiped with 10 PCs, a printer, a scanner, and an internet connection either using DSL or cellular access technology. The program was government sponsored through the Ministry of Communications and Information of the Republic of Indonesia. This program was also designed to provide education and training for the district internet kiosks operator as well as for the staffs of information technology at Garut Regency, on understanding, efficient use, management, maintenance, as well as the ethical/professional use of information to upgrade their skills. This study was then conducted to evaluate factors affecting internet penetration in rural areas of Garut Regency, West Java of Indonesia.

Performance evaluation of SIMO Least Squares channel tracking on Rician distributed channel

Wireless channel with the presence of Line of Sight (LOS) is often modeled as Rician distribution. In order to track the channel for mobile users, exponentially weighted Least Squares (LS) Single Input Multiple Output (SIMO) channel estimation is employed. By incorporating the optimum forgetting, the system performance in terms of tracking Mean Square Error (MSE) and Bit Error Rate (BER) is evaluated. It is shown that the optimum forgetting factor as well as the system performance, are elevation angle-dependent due to the rapid movement of the user in the coverage area.

Sum rate capacity of multiuser MISO designed for HAPS high speed train application

The capacity gain proportional to the number of transmit or receive antenna promised by MIMO, has attracted many interests to implement MIMO on existing terrestrial and satellite system. A complementary to those existing systems is known as HAPS, and is situated in the stratosphere around 17–22 km. One of the interesting applications of HAPS is broadband transmission to high speed trains.