Mobile WiMAX is a wireless broadband solution that enables mobile and fixed network konfergensi broadband via an extensive radio access technology and flexible network architecture. Water interface on Mobile WiMAX applying Orthogonal Frequency Division Multiple Access (OFDMA) to obtain multi-path performance is better in the environment of Non Line Of Sight (NLOS). To support the growing bandwidth channel (scalable) from 1.25 MHz to 20 MHz, IEEE 802.16e introduces the Scalable-OFDMA (SOFDMA), Mobile Technical Group (MTG) on the WiMAX Forum is developing the Mobile WiMAX system profiles that enable mobile system configured





Mobile WiMAX Architecture
According to the WiMAX Forum, Mobile WiMAX architecture consists of three main parts, namely:

• User terminals are used by end-users to access the network.

• Access Service Network (ASN), which consists of one or more BS and one or more ASN gateways that form the radio access network.

• Connectivity Service Network (CSN), which provides IP connectivity and all the core functions of the Internet Protocol Network.



Network Working Group (NWG) WiMAX Forum is an organization that has authority to design the network architecture and protocols with the Mobile WiMAX air interface that has been standardized by the IEEE 802.16e standard. NGW WiMAX defines several entities in the Mobile WiMAX network:

• Base Station (BS)
Base Station has a main function is to build a relationship with the mobile station. BS also has another function that is set micromobility management as the process of handover, radio resource management.

• Access Service Network - Gateway (ASN-GW)
ASN-GW functions to regulate the location management and paging intra-ASN, set AAA customers, and perform the function of mobile IP.

• Connectivity Service Network (CSN)
Function provides connectivity to the Internet, ASP and other common network functions.



Frequency Allocation and Duplexing Systems
In the WiMAX technology have provided some of the frequency spectrum between 2.3 GHz others, 2.5 GHz, 3.3 GHz, 3.5 GHz, 5.8 GHz and 10.5 GHz. Use of these frequency allocation is different for each country in accordance with the conditions and policies of each country. The frequency used is 2.3 GHz frequency spectrum. This frequency was chosen because the Indonesian government plans to allocate the 2.3 GHz frequency spectrum for Mobile WiMAX network (IEEE 802.16e) with a channel bandwidth used by each of 10 MHz although there is currently no definite policy. On the frequency of policy direction in Indonesia, 2.3 GHz frequency has a frequency range of 2300-2390 MHz, where 10 MHz is used for the buffer (buffer) against out-of band emission from the WLAN / WiFi 2.4 GHz


While for the system used is the TDD duplexing (time division duplex). TDD uses a single frequency channel is used as ransmitter and receivers but in a different time. Consequently TDD frame is divided into the data stream and each frame is divided into time slots for sending and receiving. This allows the transmission of data in a single frequency only.

Propagation Models for Mobile WiMAX
Propagation channel model used in Mobile WiMAX is the propagation model COST 231-Hata. COST-231 model as an extension Hatta model is limited to use with the following characteristics:

Frequency (f): 1500-2000 MHz.

Height of base station antennas (hb): 30-200 m

High antenna mobile station (hm): 10-10 m

Distance Tx - Rx (R): 10-20 km

This channel model is also called the PCS model Extension to Hata Model, which is a formula developed from Hatta Okumura model for PCS frequencies (2 GHz). Okumura-Hata propagation model defined by the following equation:



Where L = attenuation path

fc = Frequency (MHz)

hb = base station antenna height (m)

hm = mobile station antenna height (m)

a (hm) = correction factor mobile station antenna height

R = cell radius (km)

CM = 0 dB, for medium-size cities and suburban area

CM = 3 dB, for the metropolitan area.

The value of correction factor mobile station antenna height (a (hm)) is



By knowing the value of link margin from the calculation of link budget, and by using the above equation can be calculated pathloss coverage range of the cell and also the number of cells required to cover certain areas.

Cell radius



Calculation of Cell Count
Calculation of cell numbers based on radius coverage area approach to the area covered by the reviews. The selection of architecture in the plan to use cellular architecture approach. Coverage area for a cell with a hexagonal configuration is



Where:

L = Coverage area

R = maximum cell range

K = constant accounting for the secto




Mobile WiMAX System Capacity Estimation
Peak Busy Hour (PBH) is a probability that will affect the operator to predict the traffic. This will depend on the application, customer mix, etc.. So the density of traffic that must be provided is