OFDM Based WLAN Systems

This report is intended to provide an overview of the present state of WLANs with respect to physical layer issues and identify some key research issues for future generations of WLANs. The current standards (IEEE 802.11a in USA, HiperLAN/2 in Europe and MMAC in Japan) are all based on OFDM in their PHY layer. Thus, detailed attention on basics of OFDM related WLAN systems are given in the report. This is to introduce the existing techniques that are proposed or implemented in different OFDM based WLANs. A special attention is given on synchronization and channel estimation issues in WLAN due to the fact that virtually it is impossible to obtain a reasonable quality of service without perfect (or near perfect or efficient) synchronization and channel estimation. At the end of the report, some interesting topics that need to be studied in the development of future generation wireless systems based on OFDM are presented. It is worth mentioning here that the explanation on various topics presented here are in no way a complete description. For details, it is suggested to study the references that are mentioned in this report.

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