Fredric Kronestedt

Adaptive antennas for GSM and TDMA systems

Adaptive antennas have generated great interest in previous years, and at present several manufacturers and operators are separately or jointly performing field tests to gain more detailed knowledge of the potential of the technology. This article summarizes many of the experiences that have been collected since 1996 during field trials carried out for both GSM and TDMA (IS-136) by Ericsson in cooperation with two major network operators, Mannesmann Mobilfunk and AT&T Wireless Services.

Migration of adaptive antennas into existing networks

This paper addresses migration of adaptive antennas into cellular networks with a conventional antenna technique. Two strategies can be distinguished: an operator can either install adaptive antennas in all cells in one step or gradually introduce adaptive antennas in a step-by-step manner. The latter method is preferred, since it results in lower introduction costs for the operator. The goal with this study has been to investigate whether the step-by-step migration is feasible. Simulations of a realistic heterogeneous network indicate that this approach is indeed possible.

System overview and performance evaluation of GERAN-the GSM/EDGE Radio Access Network

With the now finalized standardization of the first phase of the EDGE concept and its introduction of 8PSK modulation to support higher data rates, GPRS has evolved into a third generation (3G) mobile communication system. Within its second phase, EDGE will evolve further into being capable of supporting real-time packet data and thereby providing the full range of 3G services. By adopting the UMTS quality of service (QoS) concept, together with the development of new radio bearers, support of real-time packet data is accomplished and the GSM/EDGE Radio Access Network (GERAN) is created. This paper describes and evaluates GERAN with the focus on IP multimedia and the alignment with the UMTS QoS model.

Low rate voice bearers in the GSM/EDGE radio access network

With the use of the 8PSK modulation available in the GSM/EDGE radio access network (GERAN), adaptive multirate (AMR) voice can be supported with good speech quality using half-rate (HR) or even quarter-rate (QR) bearers. In this paper channel coding schemes for 8PSK HR are evaluated in terms of quality and capacity. System level simulations show that a capacity gain of 20% can be obtained with HR bearers as compared to the default full-rate bearers in a 1/3 reuse deployment. It is also shown that the introduction of QR bearers, together with an ideal adaptation mechanism, could lead to a capacity gain of up to about 90% in a 4/12 reuse pattern. However, dynamic system level simulations indicate that both measurement periods and intra-cell handover will limit the capacity gains estimated from the static system level simulations. The simulations also indicate that the maximum system capacity can not be increased by HR/QR adaptation.