40 Devendra, Satyendra International Journal of Electronics, Electrical and Computational System IJEECS ISSN 2348-117X Volume 2, Issue1 January 2014 Propagation Characteristic and Modelling for Network Design and Planning Devendra Pratap Dept. of Electronics & Communication Noida Institute of Engineering & Technology Greater Noida, India devpratap1988@yahoo.com Satyendra Sharma Dept. of Electronics & Communication Noida Institute of Engineering & Technology Greater Noida, India satyendracommn@gmail.com ABSTRACT-Coverage is the most important parameter for network design and modelling. Coverage is the distance to which the signal can travel in geographical area with obstacles and is determined by two key metrics; path loss and received signal power. Accurate propagation models are essential in RF planning and network deployment. They are used to predict performance, and ensure quality of service after deployment. Different models have been proposed to predict path loss and signal strength.. This paper presents a comprehensive study of path loss on mobile WiMAX which has been developed to provide high throughput and wide coverage to a large number of users. In this paper we have calculated, analyzed, compared the path loss values and determined the link budget, we consider the WiMAX standard at carrier frequency, namely 3.5GHz and a variation of distances in the range of 1 to 15 km, in flat rural, suburban and urban environments. The paper discusses and implements Stanford University Interim, Cost-231, Ericsson, ECC-33 propogation model. Keywords: WiMAX · Path loss · Propagation models INTRODUCTION WiMAX (the Worldwide Interoperability Microwave Access) is one of the most promising emerging cellular mobile technologies around today. The signal propagation path is the path from the WiMAX base station antenna to the WiMAX mobile station (MS) antenna that is expected to be located at the border of the WiMAX Cell-edge, at up to 50 km distance from the BS. Mobile WiMAX, under the 802.16e standard, can deliver 75 Mbps to mobile users over 50km ranges [1]. The WiMAX specification consists of orthogonal frequency division multiplex (OFDM) with 256 subcarriers (192 data subcarriers to carry data symbols, 8 pilot subcarriers to carry pilot symbols, and 56 nulls subcarriers). BPSK, QPSK, 16-QAM and 64- QAM modulation schemed are used. The channel bandwidth can be 5 MHz, 8.75 MHz or 10 MHz Also, the number of FFT subcarriers can be chosen as 128 512, 1024 or 2048. As with any new technology, there are many issues that affect the implementation and the utilization of WiMAX. One of the most important issues is the path loss for signal propagation according to frequency and distance attenuation. The signal path loss in crowded cities with large buildings is different than the open cities or villages. Furthermore, shadowing and interference from neighbouring cells are specific factors that limit the coverage and Performance of WiMAX networks [2]. The performance of WiMAX will largely depend on the actual data rates and ranges that can be achieved. Different path loss models have been used in many cellular systems but they have not been analyzed for WiMAX to evaluate the link budget, the power outage probability and the cell coverage area. In this paper we evaluate the path loss for WiMAX at various environments of varied distances 1 to15 km and a fixed frequency 3.5 GHz. We characterize the variation in path loss over distance for various environments. In this study since the transmission from the BS to the MS is small enough it will not be affected by the earth’s curvature. Cost-231, Ericsson, Erceg, SUI, Ecc-33, Lee and the simplified free space path loss models are considered [3]. PROPAGATION MODELS The performance of a wireless system depends on the channel it operates in. Understanding the channel is important to ensure coverage with minimum infrastructure cost. Path loss models are used during network planning, deployment and operation to predict signal power at receiver locations. The successful deployment of any wireless network relies on ensuring serviced area is covered by minimal infrastructure. One of the main important parameters required to ensure service is the received signal power. During planning, propagation models are utilized to predict path loss and received signal power. Several models are available to predict path loss [5]. These models have been traditionally applied to frequencies below 2GHz.With the advent of WiMAX, it was necessary to extend these models to include the new operating frequencies and conditions. This work can be considered as an effort to provide actual field measurement and comparison to further tune and validate these models. In this section, we will introduce propagation models and explain the parameters used in their calculations. A. Free Space Loss Model (FS)