DIFFERENTIAL CODE SHIFT REFERENCE IMPULSE RADIO ULTRA-WIDEBAND TRANSCEIVER: BIT ERROR RATE TESTS AND PERFORMANCE ASSESSMENTS

Abstract

Impulse radio is a wireless communication technique in which ultra-short pulses in the range of nano-seconds are used for the transmission of information. These ultrashort pulses spread over the radio frequency spectrum covering wide range of frequency bands, creating an ultra-wideband signal. Using impulse radio makes a wireless communication system low power consuming, less complex and more immune to interference compared to sinusoidal wave based systems. Additionally, ultra-wideband offers several advantages like high data rate and ability to work under low signal to noise ratio. Therefore, many modulation schemes have been developed in order to exploit the advantages offered by impulse radio ultra-wideband, after the commercialization of ultra-wideband technology by Federal Communication Commission in 2002.

To overcome the disadvantages of existing impulse radio ultra-wideband modulation schemes, new improved Code Shift Reference schemes were proposed by our research group. Differential Code Shift Reference is one among the Code Shift Reference schemes in which the data is differentially encoded using impulse radio pulses. A prototype transceiver was developed using Differential Code Shifted Reference scheme. The transmitter uses 4 ns durational impulses to carry information. The pulses have the pulse repetition rate of 20 MHz and the bandwidth of 500 MHz, centered at 4.44 GHz. The original information is extracted from the encoded pulses according to Differential Code Shift Reference decoding algorithms in the receiver.

This thesis presents the bit error rate testing of the Differential Code Shift Reference ultra-wideband transceiver, which has not been well addressed before. Circuit level modifications were done in the transmitter to address the issue of nonlinearity. To conduct bit error rate tests, a new way of test sequence generation is proposed and the Differential Code Shift Reference encoding module in transmitter was modified to use the generated test sequences for modulation. Tests were conducted using two different wireless environments. The results from the bit error rate tests demonstrated that the system functions as it should be, meeting the theoretical design expectations.