Harri Honkasalo

WCDMA and WLAN for 3G and beyond

The WCDMA air interface was initially designed to support a wide variety of services with different QoS requirements having a maximum bit rate of 2 Mb/s. In order to satisfy the future service and application needs several technical enhancements are being studied and standardized for WCDMA in 3GPP. Even with evolved WCDMA, there is a need for another public wireless access solution to cover the demand for data-intensive applications and enable smooth online access to corporate data services in hot spots. This need could be fulfilled by WLAN together with a high-data-rate cellular WCDMA system. WLAN offers an interesting possibility for cellular operators to offer additional capacity and higher bandwidths for end users without sacrificing the capacity of cellular users. The evolved WCDMA air interface will provide better performance and higher bit rates than basic WCDMA, based on first releases of the specifications. Eventually, evolution may not be the answer to all the needs, and come revolutionary concepts need to be considered. However, before some future wireless system can be regarded as belonging to 4G it must possess capabilities that by far exceed those of 3G systems like WCDMA. Judging from an application and services point of view, one distinguishing factor between 3G and 4G will still be the data rate. We could define that 4G should support at least 100 Mb/s peak data rates in full-mobility wide area coverage and 1 Gb/s in low-mobility local area coverage. Other possible characteristics of 4G need to be further studied.

A dynamic channel allocation based TDD DS CDMA residential indoor system

We have developed a CDMA based residential indoor system that uses time division duplexing with dynamic channel allocation. The proposed indoor system shares the same frequency band as the outdoor ANSI-008 based cellular PCS network and operates within its coverage area. Due to the time division duplexing nature of the residential system, both the forward and reverse link signals are transmitted in the same frequency band in different time slots. In principle the indoor system may operate either in the PCS uplink or the PCS downlink frequency band. After extensive simulations, we conclude that underlaying such a system to the existing ANSI-008 PCS system is feasible. Addition of such a system would ultimately increase the CDMA capacity substantially.

GSM/DCS air interface enhancements for high speed data applications

There has been a significant increase in demand for high speed data services over cellular networks, particularly by PCS in North America. The paper presents a proposal for enhancement of the GSM air interface to achieve the data rate expansion. The new proposal modifies the GSM air interface to allow multiple time-slot access of the TDMA frame by a single MS. Such a solution provides the platform for GSM to support a mixture of wide ranges of services with only moderate modifications of the air interface involved where the GSM modulation and basic TDMA frame structures are retained.<<ETX>>