Spectral Precoding Technique and Method For Multiuser Using OFDM In Cognitive Radio Systems

Cognitive radios are aware of their surroundings and bandwidth availability and are able to dynamically tune the spectrum usage based on location; nearby radios; time of day and other factors. This provides for a more efficient use of the spectrum as well as reducing power consumption; and enabling high priority communications to take precedence if needed. OFDM is a method of digital modulation in which a signal is split into several narrowband channels at different frequencies. In an effort to improve radio spectrum management and promote a more efficient use of it; regulatory bodies are currently trying to adopt a new spectrum access model. At the same time; cognitive radio technology has received a lot of interest as a possible enabling technology. OFDM systems super from high out-of-band radiation. Consequently; they require methods reducing those spectral out-of-band components.This project investigate the spectrum; out-of-band radiation (OBR) and the use of extended guard interval (EGI) to reduce the out-of-band radiation of an OFDM signal when passing through different nonlinear devices for cognitive radio network. The above said work is going to be implementing on Blade RF SDR platform and the performance is going to be analyzed. BladeRFx40 is a Software Defined Radio (SDR) platform designed to enable a community of hobbyists and professionals to explore and experiment with the multidisciplinary facets of RF communication. It supports; 2x2 MIMO configurable with SMB cable; expandable up to 4x4; RF frequency range 300MHz - 3.8GHz; Stable Linux; Windows; Mac and GNU Radio software support; On-board 200MHz ARM9 with 512KB embedded SRAM (JTAG port available); On-board 15KLE or 115KLE Altera Cyclone 4 E FPGA (JTAG port available).