Tero Ojanpera

An overview of CDMA evolution toward wideband CDMA

Third-generation mobile radio networks, often dubbed as 3G, have been under intense research and discussion recently and will emerge around the year 2000. In the International Telecommunications Union (ITU), third generation networks are called International Mobile Telecommunications-2000 (IMT-2000), and in Europe, Universal Mobile Telecommunications System (UMTS). IMT-2000 will provide a multitude of services, especially multimedia and high-bit-rate packet data. Wideband code division multiple access (CDMA) has emerged as the mainstream air interface solution for the third-generation networks. In Europe, Japan, Korea, and the United States, wideband CDMA systems are currently being standarized. This article provides a comprehensive introduction to wideband CDMA. It also provides a review of the wideband CDMA air interface proposals including WCDMA in Europe and Japan, cdma2000 in the United States, and wideband CDMA in Korea.

An overview of third-generation wireless personal communications: a European perspective

An overview of third-generation wireless personal communications is presented, and the challenges to meet its demands are examined. At the ITU level, the third generation is known as IMT-2000. In Europe, the third generation of wireless personal communications is known as UMTS. Special attention has been paid in giving a brief description of the research and development, standardization, and regulatory activities. The UMTS terrestrial radio access (UTRA) concept is presented. The different ACTS projects involved in making UMTS a success are introduced.

FRAMES-hybrid multiple access technology

European Research Program ACTS (Advanced Communication Technologies and Services) started at the end of 1995 to support collaborative mobile research and development. Within ACTS the project FRAMES (Future Radio Wideband Multiple Access System) has been set up with an objective to define the UMTS radio access system. The first target of FRAMES is to investigate hybrid multiple access technologies and based on thorough evaluation of several candidate schemes select the best combination as a basis for further detailed development of the UMTS radio access system. The two hybrid multiple access evaluated schemes integrate a range of multiple access techniques that will lead to an optimised selection of the multiple access method for the UMTS. The first hybrid, slotted multiple access (SMA), has basically a TDMA platform. Furthermore, it contains a CDMA component which overcomes the near far problem of conventional CDMA. Also multicarrier techniques are included. Different bit rates can be flexibly provided by assigning different numbers of time slots, of carriers and of CDMA codes to a user. The second hybrid, code and time division multiple access (CATS) has basically a CDMA platform. It also includes an option for OFDM techniques in the downlink. Furthermore, by using multiuser detection CATS eliminates some of the typical CDMA drawbacks; thus has a very good spectral efficiency, just as its SMA counterpart.

FRAMES multiple access mode 2-wideband CDMA

An evaluation of several multiple access schemes against UMTS criteria has been carried out within the European FRAMES project. Based on this comprehensive evaluation, a harmonised multiple access platform termed FRAMES multiple access (FMA) has been designed consisting of two modes: a wideband TDMA mode with and without spreading (FMA 1), and a wideband CDMA mode (FMA 2). This paper describes the FMA 2 radio access system proposal. The FMA 1 proposal is described in Ovesjo (1997).

Frames FMA2 wideband-CDMA for UMTS

The basic principles of the physical layer of the FRAMES (Future Radio Wideband Multiple Access System) FMA2 (FRAMES Multiple Access) wideband CDMA system are described in this paper. The FMA2 is part of the FRAMES dual mode platform designed as UMTS air interface, where the harmonisation with GSM is also taken into account. The main characteristics features in the FMA2 are the asynchronous network operation and flexible layer 1 support for the variable rate transmission needs. This paper presents also performance results, which allow to conclude that the FMA2 meets UMTS air interface requirements. The FMA2 concept was a major part of the ETSI (European Telecommunications Standards Institute) wideband CDMA concept group, selected by ETSI as a basis for UMTS air interface for the paired frequency band.

Comparison of multiple access schemes for UMTS

An assessment of several multiple access schemes against UMTS criteria has been carried out within the FRAMES project. Based on this comprehensive evaluation, an harmonized multiple access platform has been designed consisting of two modes, a wideband TDMA with and without spreading and a wideband CDMA, which is presented. Both modes are compared against UMTS criteria. In general, they can both fulfill the UMTS objectives and will form the FRAMES input into UMTS standardization. However, Mode 1 seems more suitable for bursty type of traffic and in addition to FDD for asymmetric TDD operation while Mode 2 suits better for moderately varying circuit switched data in public radio environments.

A survey on CDMA: evolution towards wideband CDMA

This paper presents an overview of CDMA and discusses the main features of the future air interface access schemes namely WCDMA and CDMA2000, for IMT-2000/UMTS. Multiple access schemes and CDMA classification are introduced. CDMA past, present and future activities are presented, and the concepts and elements of CDMA are explained. Wideband CDMA schemes are also presented and conclusions are given.

Qualitative comparison of some multiuser detector algorithms for wideband CDMA

A novel wideband CDMA multiuser detection algorithm, multirate weighted parallel interference cancellation (MW-PIC) is proposed. The algorithm has been based on a fair and comprehensive comparison of a selected number of published multiuser detectors. The comparison criteria are derived by reviewing the key features of the proposed wideband CDMA systems for third generation mobile systems.

Design of a 3rd generation multirate CDMA system with multiuser detection, MUD-CDMA

A design of a DS-CDMA system based on multiuser detection is presented. Key features of the system include a flexible transport scheme, large 5.1 MHz bandwidth, coherent demodulation and fast mobile controlled handover with interfrequency handover capability. Furthermore, the major trade-offs and design choices are explained.

Overview of multiuser detection/interference cancellation for DS-CDMA

Wideband DS-CDMA has gained a lot of attention for the third generation wireless systems (UMTS and IMT-2000). On the other hand, multiuser detection has been under intense research since the formulation of optimum multiuser detector by Verdu in 1986. For the third generation wireless systems, several wideband CDMA schemes with multiuser detection have been proposed. This paper presents an overview of developments in the field of multiuser detection for DS-CDMA. Finally, possible future research directions are suggested.