Design and Implementation [chapter]

Terje Kristensen
2016 Computational Intelligence, Evolutionary Computing and Evolutionary Clustering Algorithms  
In cellular and personal communications services PCS systems based on code division multiple access CDMA a pilot signal is used on the forward link for synchronization, coherent detection, soft hando , maintaining orthogonality b e t w een base stations, and, in the future, position location. It is critical that the percentage of power allocated to the pilot signal transmitted by each base station be xed properly to ensure the ability of the CDMA network to support subscriber demand. This
more » ... reports on the design and implementation of a prototype receiver for measuring pilot signals in CDMA PCS systems. Since the pseudonoise PN signal of the pilot channel is a priori information, the receiver searches for pilot signals by digitally correlating the received signal with this known, locally generated pilot signal. By systematically changing the phase of this locally generated pilot signal, the receiver scans the received signal to identify all possible signs of pilot signal activity. Large values of correlation indicate the presence of a pilot signal at the particular phase of the locally generated pilot signal. The receiver can also detect multipath components of the pilot signal transmitted from a given base station. One issue associated with this receiver is its ability t o k eep the signal power within the dynamic range of the analog-to-digital A D converter at its input. This necessitated the design of an automatic gain control AGC mechanism, which is digitally implemented in this receiver. Simulation studies were undertaken to assist in the design and implementation of the pilot signal scanning receiver. These simulations were used to quantify how various non-idealities related to the radio frequency RF front-end and A D converter adversely a ect the ability of the digital signal processing algorithms to detect and measure pilot signals. Because the period of the pilot signal is relatively long, methods were developed to keep the receiver's update period as small as possible without compromising its detection ability. F urthermore, the high sampling rate required strains the ability o f the digital logic to produce outputs at a rate commensurate with real-time operation. This thesis presents techniques that allow the pilot signal scanning receiver to achieve real-time operation. These techniques involve the judicious use of partial correlations and windowing the received signal to decrease the transfer rate from the A D converter to the digital signal processor. This thesis provides a comprehensive discussion of these and other issues associated with the actual hardware implementation of the pilot signal scanning receiver. iv the universe, whose laws we lesser engineers attempt to understand and use for the good of mankind, for granting me life and health to complete this thesis. I thank my parents for their unsel sh devotion to me throughout my life and for setting an example to me of living by one's principles. I thank my sister roommate for her cooking and cleaning over the past one and one-half years, and my girlfriend, Yufei Wu, for her encouragement and support. My advisor, Prof. Rappaport, gave me another chance at making good of my life and arranged for me to lead this interesting project. For this, for befriending me, and for providing technical suggestions at crucial moments throughout the course of the project, he has earned my gratitude. Profs. Reed, Tranter, and Sowerby also provided technical suggestions at various points in the project. Thanks to Dr. Bob Boyle for his meticulous reading of the thesis draft and for helping me to sort out various issues related to the sampling rate. Thanks to Profs. Brown and deWolf, members of my graduate committee, for their readings and suggestions on this thesis. , provided invaluable suggestions to the project. It was truly a blessing to have been associated with so many w onderful students at the Mobile and Portable Radio Research Group MPRG at Virginia Tech. Many of them helped me with di culties related to electronics, computing, simulation, and system design throughout the course of this project, and I would desire that they know h o w m uch I appreciate their time and courtesy. By name, they are as follows:
doi:10.2174/9781681082998116010006 fatcat:vu7l6pwbnbggfbcigdqauwinfy