SYSTEM LEVEL DESIGN AND DEVELOPMENT OF IBMS RADIO

Abstract

The IBMS target is the vision of the future broadband mobile communications system. Applied modulation schemes advantageously deal with low data rate and high data rate applications. This thesis will discuss the system level design and implementation of IBMS radio with different applied modulation schemes. The research was consisting of two phases. In the phase one, design and simulation of transceiver of IBMS radio was performed using ideal blocks in Advance Design Systems (ADS). All sub networks were combined into a single block of Transmitter & Receiver. Full duplex was selected for simulation of transmission and reception because of unavailability of T/R switch model in ADS, while in implementation of system half duplex was used. An attenuator is used to represent air attenuation in the real environment. Single tone HB simulations are performed. A ‐3dBm IF signal from modulator was amplified using three stage amplifiers to 39dBm in normal operation and up to 45dBm for a 6dB PAPR application. This transmitted signal is received and amplified using LNA with 17dB gain and 1 dB NF. It amplifies an input signal of ‐60dBm to ‐43dBm. This signal is then passed through an automatic gain control (AGC) circuit with a dynamic range of ± 40dBm. AGC circuit is consisting of two stage variable gain amplifiers, a three stage log amplifiers circuit and an operational amplifier. The purpose of an AGC is to give constant output signal, which is achieved in our simulations. The results are then verified in the second phase by design and implementation of individual sub‐systems. Some of the ideal blocks are then replaced in the system level simulations by real tested designs. Some of the designs like modulator, demodulator, attenuator etc. are fabricated and tested but their models were not available for system level simulations. Similarly few designs are still in progress, like an AGC which will be included in the system level simulations to replace ideal block in the receiver. Three stage amplifiers, a band pass filter in transmitter section and an LNA with real design in receiver was replaced. System level simulations were performed again and the required results were obtained.