Parag Arun Agashe

Evolution of cdma2000 cellular networks: multicarrier EV-DO

The evolution of cdma2000 1xEV-DO systems to multicarrier EV-DO (supported by 1xEV-DO Revision B) is discussed in this article. Multicarrier EV-DO offers a backward-compatible upgrade to leverage existing 1xEV-DO networks and terminals. It allows a software upgrade to multicarrier EV-DO using 1xEV-DO Revision A base station hardware. Multicarrier operation achieves higher efficiencies relative to single-carrier by exploiting channel frequency selectivity, improved transmit efficiencies on the reverse link, and adaptive load balancing across carriers. Multicarrier EV-DO enables very high-speed download, high-resolution video telephony, and improved user experience with concurrent applications. The sources of higher efficiency are discussed in detail in this article. It also enables hybrid frequency reuse deployment scenarios that enable spectrally efficient operation and significant improvement in edge coverage performance with hardware-efficient implementations. The evolved wider bandwidth systems (up to 20 MHz) based on multicarrier EV-DO offer operators a cost-effective solution that competes favorably with other technologies.

GPS receiver sensitivity enhancement in wireless applications

A major concern in using GPS is satellite visibility, especially in urban canyons and indoor applications. We demonstrate techniques to use the communication link to enhance the sensitivity of GPS receivers in wireless applications. We analyze the performance of the different sensitivity enhancement schemes. Receiver operating characteristics (ROC) and improvements in sensitivity are presented and discussed.

LTE Relay Architecture and Its Upper Layer Solutions

The relay technology is an essential piece of LTE-Advanced in its pursuit of cost effective capacity enhancement and coverage extension. Simple RF repeaters have been widely used in cellular technologies to offer coverage extension. However, they cannot distinguish desired signals from interference and noise and are unable to operate with sophisticated mechanisms, such as power control, beam-forming, and adaptive modulating/coding. As a result, simple RF repeaters do not provide capacity enhancement nor do they reach the capacity potential of extended coverage areas. The use of more sophisticated relay in cellular technologies is relatively new. With its great benefits in QoS differentiation, capacity enhancement, and coverage extension, the development of LTE relay technology faces challenges in providing backward compatibility, minimizing complexity, providing sufficient QoS differentiation, reducing over the air overhead, and ensuring security. This paper addresses these challenges with solutions in the aspect of relay architecture and upper layer designs.