American Journal of Engineering Research (AJER) 2014 www.ajer.org Page 258 American Journal of Engineering Research (AJER) e-ISSN : 2320-0847 p-ISSN : 2320-0936 Volume-03, Issue-01, pp-258-267 www.ajer.org Research Paper Open Access RF Propagation Measurement and Modelling to SupportAdept Planning of Outdoor Wireless Local Area Networks in 2.4 GHz Band J. Isabona, and K.Obahiagbon 1 Department of Basic SciencesBensonIdahosa University, PMB.1100, Benin City, Nigeria 2 Department of Mathematics and Computer Sciences Abstract: -Radio Frequency (RF) propagation is the study of how radio waves broadcast over distances. One of the main problems in mobile radio communication is the loss of propagated RF signal power at the receiver due to fading. When the fading is very strong, the signal is blocked. Modeling of the signal propagation loss is an important element of the design and performance analysis of wireless communication systems.The initiative of RF propagation modeling is to devise a model that can predict the signal coverage of an access point placed at a certain location in an environment.Propagation models help network planner to estimate the signal coverage and pathloss for a given deployment plan, as well as perform automated placement of access points. This paper presents a measurement based Log-distance propagation model for effective planning of outdoorWLAN in the 2.4 GHz Band. Measurements were carried out over a distance to determine various received power levels from a fixed WLAN access pointtransmitter; these values were applied to some path loss model equations to obtain the mobile radio planning parameters such as the path loss exponent, the mean path loss intercept and AP cell range. The results obtained show that path loss exponent was 1.85 while the mean path loss intercept was mean path loss intercept 84. Hence the log model for the design of a mobile radio link in the test bed area is PL(dB) = 84+ 1.85log (d). In general, results show that the obstructions in the environment considered here had little effect (not much) on radio signals. Keywords: -RF propagation modeling, Log Distance Pathloss model, WLAN radio link design I. INTRODUCTION The far-reaching demand for wireless communicationtechnologies is ever increasing in all the human- life activities and this has boosted the development of Wireless Local Area Networks (WLANs).Among the WLAN standards, the IEEE 802.11 [1] is the most popular one. A Schema of the IEEE 802.11 standard is represented in figure 1. The IEEE 802.11 standard defines both the physical (PHY) and medium access control (MAC) layers of the network.The basic network building block defined by the standard is the infrastructure Basic Service Set (BSS) which is composed of a single Access Point (AP) connected to a wired backbone network providing wireless connectivity to a bunch of mobile users.Thus, Aps, normally routers, are base stations for the wireless network. However, it is no easy task to decide on the number and locations where these APs have to be fixed in an outdoor or indoor environment so as to provide not only coverage but ensure minimum signal strength at all node points, requisite bandwidth, in the presence of obstructions, reflections and signal interference. Design of this nature is very complex and needs proper modeling and formulating the problem as an optimization problem with several constraints. Thus, the development of efficient transmission, operation and management WLAN technologies requires a greater precision on the estimations of the system signal coverage, which is given by propagation pathloss models. This is usually done in order to obtain “total coverage” with which the operator attempts to assure the quality of service.Propagation models to help network designer estimate the signal coverage and pathloss for a given deployment plan, as well as perform automated placement of access points. For this reason a precise and flexible prediction methodologies of signal coverage with easy implementation is needed.