J. Gonzalez Villarruel, L. Gonzalez P., Andrés Garcia

Wireless communications and internet continue to impulse commercial and economic activities. Wireless devices have contributed greatly to this progress by expanding internet access to outdoor and mobile locations. But as wireless access services increase, more complex and more compact wireless devices are required to respond to the demand. In fact, as integration increase, system analysis and design becomes a complex task due to the multiple areas involved in only one design. For example to address wireless receiver designs, we need to understand RF, semiconductors, digital modulation, communication theory, wireless standards, transceivers, signal propagation and microwave fields in order to analyze all the analog and digital signals involved. Due to the economic and technical importance of this field, multiple text and papers have already been reported in the literature however, few of them propose a method to address the RF design based on analytical tools, some texts address the subject only from a theoretical point of view and others only propose cooked formulas. RF design, technologies and applications, is evolving so fast reason why only few texts offer a unified design method. This paper then proposes a method to analyze RF wireless communications receivers section based in an optimum receiver. Due to the complexity of the subject, this paper will be limited to RF and receiver impairments and performance impact. For this reason wireless channel impairments will not be consider in this case.

"Seamless Roaming between Cellular Packet Data Networks (2.5G/3G) and Wireless Local Area Networks. A Interworking Strategy Survey".
Ricardo Camarena Ramos, Luis Fernando González.
CIINDET'O4

Implementation of Third Generation Mobile Networks (3G) has been delayed, but the demand of high data-rate services has increased in the last years. Today, various wireless technologies exist which focus on the solution of different demands. On one hand, there are wireless technologies best suited for mobility but offering low throughput (cellular packet data networks, aka 2.5G systems); on the other hand, there are wireless technologies that offer higher throughput but small footprint of access (Wireless Local Area Networks). As can be seen, a lot of wireless/mobile technologies exist which does not coexist making difficult for the end user to choose the one that better fits his/her demands. The solution to this problem is coming with the help of one of the paradigms of convergence of voice and data networks, i.e, the interworking of hybrid networks. For wireless packet data transmission we count today with two alternatives: cellular packet data networks and Wireless LAN. Several operators around the world are interested in combining the advantages of both in a hybrid network in which subscribers can roam seamlessly between these networks. The main objective of this study is to present the state of the art for the interworking of these networks as well as the trends.

"Quasi Mobile IP-based architecture for seamless interworking between WLAN and GPRS networks"
Ricardo Camarena Ramos, Luis Fernando González.
ICEEE'05

Fixed local service and cellular operators around the world have shown interest in providing WLAN services to their subscribers together with traditional packet data cellular services in a hybrid infrastructure in which subscribers can roam seamlessly. This document specifies the system description for a seamless interworking between a GPRS system and Wireless Local Area Network (WLAN). The main objective is to extend the services available in IP networks (e.g. Internet) providing session persistence to both cellular packet data network subscriber and WLAN users. A Quasi Mobile IP architecture is proposed as a suitable solution together with a network discovery and roaming algorithm. The proposed framework allows for independent system engineering, reuse of current infrastructure, charging, robustness and security. A new node is introduced called Home Agent and minimal changes on MN software providing the necessary seamless interconnection capability to any user which owns a terminal with GPRS and WLAN interfaces as well as valid credentials to access both networks.