Agilent 5991-4596EN OFDMA Introduction and Overview for Aerospace and Defense Applications - Application Not free download

File name 5991-4596EN OFDMA Introduction and Overview for Aerospace and Defense Applications - Application Not

Keysight Technologies OFDMA Introduction and Overview for Aerospace and Defense Applications Application Note Introduction This application note is for Aerospace and Defense (A/D) engineers considering or developing systems using OFDM or OFDMA. Understanding the complexities of OFDM and OFDMA can be challenging, particularly if one has not previously worked with commercial wireless standards. The intent of this application note is to provide a brief introduction to OFDM and OFDMA, with an eye toward the special considerations and environments for A/D applications. The concepts presented in this application note will serve as an initial basis to further understand commercial standards-based OFDM and OFDMA such as LTE using additional reference provided at the end of this application note. Orthogonal frequency division multiplexing (OFDM) has become attractive for a wide range of commercial wireless systems because it delivers high data throughput in real-world environments, along with spectral efficiency, and link flexibility. OFDM first came into wide use more than a dozen years ago in wireless local area network (LAN) applications and has recently spread rapidly to support wireless mobile voice and data in the form of the 3GPP long-term evolution (LTE) standard and the Worldwide Interoperability for Microwave Access (WiMAX) standard. The baseband processing power that OFDM demands for both signal generation and demodulation is no longer a barrier to implementation, and in recent years systems have rapidly increased their throughput and efficiency. Commercial systems have implemented progressively wider bandwidths and sophisticated coding and multiplexing schemes to efficiently serve large numbers of users with ever-greater data demands. OFDM's low symbol rate and multicarrier structure, combined with coding and forward error correction, allow it to operate effectively in channel conditions degraded by interference, jamming, and frequency selective fading. Because of its multicarrier structure, OFDM is readily extendable to simultaneous multiple-access capability by mapping subcarriers to users in a scheme called orthogonal frequency division multiple access or OFDMA. This multiple access approach is especially attractive because multiple users can be supported in a flexible fashion with only minor changes in the air interface. In addition, Multiple-Input Multiple-Output (MIMO) techniques can be used with OFDM and OFDMA systems to further improve data throughput in the presence of multipath environments. This combination of benefits makes OFDM attractive for flexible deployment in Aerospace and Defense (A/D) applications, both terrestrial and marine. One attractive application example is video streaming for improved situational awareness. A/D users could potentially tak