Karl Kammerlander

GSM: Evolution Towards 3rd Generation Systems

From the Publisher: Dynamic evolution of GSM presents a platform for the introduction of UMTS. Presently, efforts are directed towards the standardization of the UMTS air interface in ETSI. Major trends in progress towards new radio interfaces are outlined including contributions from pan-European projects such as ATDMA, which was carried out under the RACE II framework, and the ACTS project AC090 Frames.

C 900 - An Advanced Mobile Radio Telephone System with Optimum Frequency Utilization

The paper presents a survey of a new approach to advanced system solutions for mobile radio telephone systems. It is shown that, by the combination of both radio techniques and microprocessor data capabilities, improved means are available for controlling the specific multiple propagation and interference influences within the mobile radio environment. The aim of the system structure is to achieve the best possible frequency channel utilization, system availability, and cost benefits for deployment and users if traffic demand grows. The paper shows the different types of switching functions in public land mobile networks. Problems, as caused purely by radio conditions, are controlled within a defined radio exchange function, allowing the optimization of individual cell parameters. It is shown that distance measurement is the most reliable means of detecting cell boundaries. New approaches for system control channels lead to synchronous operation of base stations. The system operates with off-air call setup and queueing to improve channel utilization. Full national and international roaming capabilities are provided. During all calls, continuous digital link control is maintained to allow the radio exchange function in call condition. This new approach leads to different types of handoff to suit specific situations. Speech scrambling provides subscriber privacy.

Benefits of combined TDMA/CDMA operation for third generation mobile radio systems

The multimedia landscape requires a new approach to powerful mobile radio systems, termed Universal Mobile Telecommunication System (UMTS), which must be suited for both narrowband and broadband transmission. The UMTS therefore requires a balanced hybrid multiple access scheme. This paper presents an attempt to combine the F/TDMA and F/CDMA advantages in F/T/CDMA which facilitates a favourably high economical efficiency, regarding the investments of future network operators, as well as high channel efficiencies, in terms of a high number of traffic channels per transceiver. F/T/CDMA thus leads to a low number of small base stations (BSs) and a high spectral efficiency by dense frequency reuse. Furthermore, F/T/CDMA allows backward compatibility with GSM. The paper explains the basic relations of mobile radio systems in regard to spectral efficiency, economical efficiency and multiple access schemes as well as the most important ETSI-UMTS requirements. A novel approach to assessing F/T/CDMA by means of joint detection (JD) techniques, termed JD-CDMA, is presented. JD-CDMA allows one to overcome the drawbacks of conventional CDMA mobile radio systems.

On multicarrier CDMA mobile radio systems with joint detection and coherent receiver antenna diversity

The combination of code division multiple access (CDMA) and multicarrier (MC) transmission techniques, termed MC-CDMA, is considered a promising alternative to conventional DS (direct sequence)-CDMA. An MC-CDMA concept which is well-suited for mobile radio applications is described. This concept overcomes the disadvantages of previously proposed concepts. In MC-CDMA mobile radio systems, signal reception is impaired by time-varying multipath propagation. The impairments can be reduced by coherent receiver antenna diversity (CRAD). The application of CRAD in combination with joint detection (JD) techniques to the more critical uplink of MC-CDMA mobile radio systems is investigated. Four JD techniques for CRAD are presented and their performance are studied.

On Multicarrier Detection and Coherent CDMA Mobile Receiver Radio Systems with Joint Antenna Diversity

The combination of code division multiple access(CDMA) and multicarrier (MC) transmission techniques,termed MC-CDMA, is considered a promising alternative toconventional DS (direct sequence)-CDMA. For this reason, recent research activities haveconcentrated on the application of MC-CDMA to mobileradio systems. In this paper an MC-CDMA concept which iswell suited for mobile radio applications is described. The described MC-CDMA concept overcomesdisadvantages of previously proposed concepts. InMC-CDMA mobile radio systems, signal reception isimpaired by time-varying multipath propagation. Theimpairments can be reduced by applying diversitytechniques. Coherent receiver antenna diversity (CRAD)is especially attractive because only the signalprocessing at the receivers must be modified. In thiscommunication, the application of CRAD in combination withjoint detection (JD) techniques to the more criticaluplink of MC-CDMA mobile radio systems is investigated.It is explained that the deployment of JD techniques for CRAD is an effective countermeasure againstthe influence of the mobile radio channel on the systemperformance. Four JD techniques for CRAD which areapplicable to MC-CDMA are presented. Their performances are studied in bad urban, typical urban, andtypical macrocellular environments. It is shown thatMC-CDMA allows a favorable performance compared to otherCDMA concepts.