Mobility in Ad Hoc-Based Network with Active High Traffic

Abstract

This paper used OPNET IT Guru academic edition to simulate four scenarios of ad ho based mobile local area networks in the existence of active high traffic applications: FTP and Database. In order to study the effect of hidden node problem due to mobility, the first and the third scenarios did not use the request to send (RTS) / clear to send (CTS) mechanism and the second and the fourth scenarios used the mechanism. The effect of mobility on TCP and applications performance is also shown. The paper showed how mobility affected the congestion window size, WLAN load, Throughput, Media Access Delay, received traffic for FTP and Database, response time for database and the retransmission parameters in case of using and not using RTS/CTS mechanism in the existence of FTP and Database traffic. The results revealed that with respect to the mobile client and the FTP application, when the RTS/CTS mechanism is used, the congestion window size is reduced, and the mobile servers have higher data load than fixed ones although stopped transmission earlier. With respect to the fixed client, however, the mobile servers have lower load and congestion window size. As for the database application and the mobile client, using the RTS/CTS mechanism and having the servers stayed mobile causes the congestion window size be low, with the fixed client, however, there was no difference whether the servers are mobile or fixed. The WLAN and throughput for the fixed servers are lower than the mobile ones and higher with the RTS/CTS scenarios. Also, there was no effect on the status of the server (mobile or fixed) on the media access delay but employing the RTS/CTS mechanism reduced the value. The highest received client traffic with respect to the mobile client is reported in the server is fixed and the RTS/CTS mechanism is employed with database application and in the mobile server with no RTS/CTS for FTP application. The minimum DB Query response time as a global value was reported when the RTS/CTS mechanism was used while the server was fixed and had a highly noticeable value when the server was fixed and no RTS/CTS mechanism was used.