International Journal of Wireless & Mobile Networks (IJWMN) Vol. 4, No. 3, June 2012 DOI : 10.5121/ijwmn.2012.4309 141         Jyoti Kolap#, Shoba Krishnan*, Ninad Shaha$ #Department of Electronics and Telecommunication Mumbai University. #kolapjyoti@gmail.com * Department of Electronics and Telecommunication Mumbai University. *shobakrishnan@hotmail.com $ Computer Centre, IIT Bombay. $ninadshaha@iitb.ac.in ABSTRACT IEEE 802.11n Draft is next-generation wireless LAN standard. This article gives detailed description and comparative study of A-MPDU and Two level frame aggregation mechanisms proposed in the latest 802.11n draft standard, which improve extensively the channel efficiency and data throughput. Ns 2 simulator is used for simulation of 802.11n WLAN frame aggregation. Simulation results confirm that A- MPDU, and Two level frame aggregation methods improve extensively data throughput. It analyse the performance of each frame aggregation scheme in distinct scenarios, and it conclude that overall, the two-level aggregation can improve throughput performance of 802.11n. Two level aggregation can more effectively deliver data from multiple sources, PDR rate is much higher with much lower delay and Two level aggregation consumed less energy as compared with A-MPDU approach.. KEYWORDS NS-2 IEEE 802.11N, Frame Aggregation, A-MPDU, Two level aggregation, 1. INTRODUCTION In the recent years, wireless LAN (WLAN) is most popular for mobile equipment’s. Because the equipment cost decreases and the data delivery rate becomes higher. IEEE802.11 WLAN is most popular network in wireless networking, because of its advantages its system possesses such as interoperability, mobility, flexibility, and cost-effective deployment. In July 2002, to achieve higher data rate, IEEE 802.11 standard working group established the High-Throughput Study Group (HTSG). The IEEE 802.11n (“n” represents next- generation) resolution to compose a high-throughput (HT) extension of the current WLAN standard that will increase transmission efficiency, throughput and reduce compulsory overhead. The 802.11n standard offers several advantages over previous wireless LAN technologies. The most majorable advantages are substantially improved reliability and greater application data throughput. However, the low transmission rate of its medium access control (MAC) and a physical (PHY) layer protocol restrict to support high data rate application. Current WLAN systems having difficulties with the increasing expectations of users and with volatile bandwidth and delay-boundary demands from new higher data rate services, such as high- definition television (HDTV) ), file transfer, and online gaming, video teleconferencing, multimedia streaming, voice over IP (VoIP. The major aim of the IEEE 802.11n Task Group (TGn) is to have maximum data throughput of at least 100 Mb/s. IEEE 802.11n gives recent propositions for PHY which includes multiple input multiple output (MIMO) antennas with orthogonal frequency division multiplexing (OFDM) and various channel binding mechanism.