Arfianto Fahmi

Coexistence LTE with GSM and UMTS - performance analysis using seamcat simulation

The LTE (Long Term Evolution) technology is expected to offer a number of distinct advantages over other wireless technologies. Scarcity of spectrum had encouraged regulator and provider to refarmed the spectrum. Spectrum refarming for LTE in 900MHz, 1800 MHz or 2100 MHz frequencies band is considered to trigger the potential degradation of existing services such as GSM and UMTS. The simulations results decribe that in those frequencies band options, LTE can well coexist with other technologies in the ecosystem such as GSM and UMTS. Overall simulation results show that at 1800 MHz while LTE is interfered by LTE and others such as GSM and UMTS, the performance is lower than other frequencies, so the best option is at 900 MHz or 2100 MHz of the frequencies.

Performance evaluation of inter-cell interference of LTE-A system using carrier aggregation and CoMP techniques

Long Term Evolution Advanced (LTE-A) is a promising technology to achieve peak data rate of up to 1 Gbit/s in the downlink and 500 Mbit/s in the uplink. Because adjacent cells employs the same frequency in universal frequency reuse scheme, interference between adjacent cells may degrade the bit rate, particularly at the cell edges. Inter-Cell Interference Coordination (ICIC) based on carrier aggregation as well as Coordinated Multipoint (CoMP) transmission and reception techniques have been considered as promising techniques to overcome the interference problem and to improve the bit rate at the cell edges. ICI problem can be mitigated by using different arrangements of frequency-bands allocations and possibly with different transmission power, distinguishing between the cell centre and the cell edge users. In this paper, mitigation of inter-cell interference using carrier aggregation (CA) and coordinated multipoint (CoMP) techniques are evaluated through computer simulaton. The simulation employs different frequency allocation schemes, fractional frequency reuse, different transmission powers, and different radio resource scheduling algorithms to evaluate and to enhance cell edge performance, bandwidth efficiency and throughput. The performance is evaluated in terms of SINR as a function of the number of femtocell users, and the separation distance from interfering cells. The performance is then compared between conventional technique, CA technique and the combined CA and CoMP techniques.

Enhancement of MC-CDMA performance system using Rotated Modulation

The transmission system with high data rate and high mobility is needed. However, the system is susceptible to frequency selective fading and fast fading. We propose MC - CDMA system with Rotated Modulation that be able to solve the problems. MC - CDMA is a combination of OFDM and CDMA system which offer high spectral efficiency. However, this system still requires high power, so in this study Rotated Modulation is added to reduce the power. Rotated Modulation implements rotating signal constellation and use quadrature and inphase interleaver. The simulations result show MC - CDMA with Rotated Modulation produce a system that require less power compared with MC-CDMA non Rotated Modulation systems.

Utilizing mean greedy algorithm using user grouping for chunk allocation in OFDMA systems with carrier aggregation

In this paper, utilizing user-order chunk allocation algorithm for OFDMA systems using carrier aggregation environment is proposed and evaluated. Chunk allocation algorithm is performed based on mean greedy algorithm which has low complexity. In order to adopt this algorithm to those system, all users are divided into a certain group in accordance with the number of available aggregated carriers. The simulation results are shown that the performance and time complexity of the proposed scheme is same with the system without user grouping. Therefore, the proposed scheme could be considered to realize in LTE-Advanced platform.