Abdul Halim Ali

Wifi signal propagation at 2.4 GHz

The purpose of this research is to analyze the signal propagation at 2.4GHz frequency. This frequency is reserve for ISM band which is commonly used in Wifi / HyperLAN. Three types of environment scenarios are involved which are indoor propagation, outdoor propagation and propagation between buildings. The propagation measurement is taken at University Kuala Lumpur, British Malaysian Institute. The measured path loss signal is analyzed and compared using the Log Distance Model. The simulation results obtain from this study were as expected. The results obtained from simulation and measured data are accordingly same and related to each other. Moreover, the new path loss coefficient factor, n yields from the Log Distance Model itself which applicable for frequency at 2.4GHz is obtained in this research. The n value plays an important role for path loss prediction since it represents the different obstruction which the signals pass through.

Investigation of indoor WIFI radio signal propagation

The purpose of this study is to analyze the WIFI signal propagation, using IEEE 802.11g radio interface. In most cases, the WIFI radio interface is installed by the people who are not familiar with the system, especially when dealing with signal propagation at high frequency. Hence, there is a need to understand this signal behavior particularly in indoor scenarios. This study focuses indoor signal measurement and prediction. The measurement and prediction of this signal propagation is taken at the campus environment of University Kuala Lumpur British Malaysian Institute. Signals were monitored using a fixed Cisco Aironet 1200 Series access point (AP) and NET STUMBER software runs on portable computer. The Log Distance path loss model is used as the mathematical analysis. The measured data is compared with mathematical model to obtain the new possible path loss coefficient, for 802.11g radio interface.

The Performance of VoIP over IEEE 802.11

Voice over Internet Protocol is a technology that enables to transport voice over Internet Protocol. The growth of this technology is due to the integration of voice and data traffic over wireless infrastructure. The low cost of voice usage on internet and wide spread of wireless technology has an advantage to implement VoIP system in today IP network. This study investigates the performance of VoIP over different IEEE 802.11standard. The focus of the study will be on IEEE 802.11 b/g/n standard. Data related to the performance parameter of the wireless network and the voice quality will be collected. The qualities of voice are analyzed and summarize into a graph between different Wireless LAN physical layer in deployment of WLAN in the future.

A new rake receiver design for long term evolution - advance wireless system

A Rake receiver is a radio receiver designed to counter the effects of multipath fading in wireless communications. It does this by using several “sub-receivers” each delayed slightly in order to tune in to the individual multipath components. Rake receiver preceding a maximal ratio combining becomes an optimum receiver in the sense of highest signal-to-noise ratio. A Rake receiver is part of the standard defined by 3GPP for WCDMA mobile systems. Multiple Input Multiple Output technology has attracted attention in wireless communications, because it offers significant increase in data transmission rates without additional bandwidth or transmit power. MIMO could increase spectral efficiency of a system. The main idea of this paper is to deploy a Rake receiver over MIMO antenna in Long Term Evolution - Advanced systems with the main aim is to further increase the spectral efficiency.

Investigation of outdoor fading model over indoor environment

Wireless access network has becoming vital tools in maintaining communications especially at home and workplaces. Due to cost effective, easy to install and maintaining wireless access network or wireless local area network has becoming the most favourable as compare to wired local area network. The needs of high speed wireless access network are a major requirement to ensuring the system work very well. IEEE802.11n promises upto 600Mbps data throughput is a beginning of a new era of WLAN. However, IEEE802.11n operates at 5GHz UNII band which limit the coverage area. This paper is to investigate the RF indoor signal behaviour and to predict the indoor signal strength by using an outdoor fading model particularly the Extended-Hata model. It is found in certain indoor condition the outdoor fading could be used to predict the RF indoor signal strength.

The impact of voice traffic on UniKL-BMI campus network

Organizations have come to realize that it makes sense to converge their voice and data networks. A single Internet protocol (IP) network infrastructure that carries voice signals as well as digital data can be installed, maintained, and managed much more easily, and less expensively, than separate voice and data networks. However, implementing new applications such as voice on an existing network is not an easy task as plug and play. Successful VoIP deployment needs proper planning and understanding of the current network traffic, and of the implementation of the VoIP and its technology. The objective of this dissertation is to investigate and evaluate the capability of a campus network to carry voice traffic on the network. The study is focused on the factors, such as delay, jitter, packet loss, bandwidth availability, etc., that affect the performance of the network and voice quality. Since the network to be tested is not available, a model resembling a real campus network was used and simulated using OPNET simulated under three different traffic loads. Comparisons were made to evaluate the performance and voice quality based on the outcome obtained from the simulations

The performance of video streaming over wireless-N

The usage of video streaming over the wireless devices especially the smart mobile phone is growing very rapidly. However to maintain the quality of service is a challenging tasks. The parameters such as Delay, Packet Loss and Jitter play important roles in ensuring the quality of video streaming over WLAN. In this paper, the performance of video streaming over wireless-N was studied in two different wireless devices which are the notebook computer and the smart phone. The notebook computer operates at 5GHz on Window operation systems and a smart phone operates at 2.4GHz on Android platform. As expected, the quality of video streaming transmitted at 5GHz outperformed the 2.4GHz transmitted signal. The performance measurements were captured by using Omnipeek and PRTG software.

Investigation of indoor Wireless-N radio frequency signal strength

Wireless local area network has become the most popular networks in connecting to internet especially at home, universities, hotels and workplaces. Therefore understanding the radio frequency behaviour of WLAN is vital in ensuring the best possible coverage. Wireless-N system operators in two frequencies band which are the 2.4GHz ISM band and 5GHz UNII band. However this paper investigates the radio frequency propagation behaviour at 5GHz. The radio frequency signal strength measurements were recorded at University Kuala Lumpur British Malaysian Institute and focuses in indoor environment. The measured radio frequency signal strengths are analyzed and compared with the simulated response of the modified Okumura-Hata propagation model. It is found that the modified Okumura-Hata propagation model could be used to predict the radio frequency signal strength for indoor environment.

The comparison study of RF signal strength between IEEE802.11b/g and IEEE802.11n

Wireless local area network has become the most popular tools in maintaining internet communications especially at home, universities, hotels and workplaces. This is due to cost effective, fast deployment, provide high data security, reliability, easy to install and maintaining as compared to wired local area network. The Wireless local area network operates in two frequency bands. The IEEE802.11b/g operates at 2.4GHz ISM band, IEEE802.11a operates at 5GHz UNII band where as IEEE802.11n operates in dual-band of 2.4GHz and 5GHz. Both the ISM and UNII are unlicensed bands. Basically, doubling the operations frequency would reduce the coverage distance however manufactures claiming the IEEE802.11n could increase the coverage areas. According to Newtons Inverse Square Law, where the received RF signal strength is proportional to the inverse square distance from the source. This paper investigates the coverage performance between IEEE802.11b/g and IEEE802.11n.

Coverage Enhancement Through Fixed Repeater Network in UMTS

Providing 100% reliable radio coverage within their service area are very challenging task to mobile operators. Especially, in an area that experiences abnormal attenuation to radio frequency (RF) such as valley or man-made structure such as tunnel, subway station, or underground parking on the whole upset this goal. These areas need to be removed by enhancing the weak RF signal in these zones. Building a new base station (BS) in these areas is very uneconomical furthermore some of these areas where establishment a BS is impossible. Therefore the use of repeaters is a good alternative and cost effective to solve these problems. This paper will presents the simulation results of repeaters in 3rd generation (3G) mobile networks based on Wideband code division multiple access frequency division duplex (WCDMA FDD)