Written by: Zhongping Zhang, Franz Heiser, Jürgen Lerzer and Helmut Leuschner
Download PDF file
WCDMA, one of the technologies selected for the air interface of the 3GPP standard, is widely used in emerging third-generation mobile communication systems. This interface supports data rates of up to 2 Mbit/s on a common 5 MHz frequency carrier. Moreover, with the introduction of HSDPA, the peak service rate for packet access in the downlink can be increased to more than 10 Mbit/s. Ericsson’s radio base station has been designed to comply with the 3GPP standard. The kernel part of WCDMA technology has been implemented in the baseband of the radio base station. Compared to previous generations, the baseband signals in WCDMA are spread with a high chip-rate code at 3.84 megachips per second on a 5 MHz frequency band. This is much wider than the frequency band used in GSM, cdmaOne and CDMA2000, or PDC. Therefore, to process the signals, more advanced technology is deployed in WCDMA baseband. Ericsson’s baseband technology uses the very latest ASIC, DSP, and FPGA technologies.
Numerous requirements are being channeled toward the baseband platform, both to support a technical implementation of WCDMA and to satisfy operator and radio network management points of view. Being the kernel in WCDMA, the baseband platform must be able to efficiently handle the entire life cycle of an RBS, from initial deployment, with a low-cost, low-content focus, to subsequent scaling for newly developed services and traffic growth. Moreover, it must do so while networks are evolving and expanding with more users and new mixes of end-user services. New radio network functions and features will also be added through base station hardware and software to perfect the WCDMA system.
The authors describe the implementation of Ericsson’s WCDMA baseband. They also show how it has been prepared to grow with and meet the needs of future developments by facilitating small, incremental upgrades and thanks to a flexible architecture that supports the expansion of the uplink and downlink together with critical functionality that resides in loadable hardware.
[First published in Ericsson Review no. 01, 2003]
