3GPP W-CDMA systems: design and testing

Newly emerging wireless signal formats can present significant design challenges to the system design engineer. Wideband code division multiple access (W-CDMA) can present many engineering design and verification challenges, due to its physical layer complexity as well as complexities that can arise when integrating RF and baseband designs to achieve a working system. System design engineers typically have the task of interpreting standards specifications, first for partitioning subsystem requirements, then verifying that the end-to-end system design (typically including both baseband and RF designs) will meet specifications when they are finally integrated. This article considers a case study that illustrates the importance of simulating baseband and RF designs together to accomplish this task. Specifically, a conceptual system design that includes system models, a fixed-point finite impulse response filter, and transistor-level circuit design is simulated and verified together against measurements defined in the third-generation partnership project (3GPP) W-CDMA standards specifications. Tradeoffs between improving either the RF or baseband design to meet overall system specifications will be discussed. Finally, design verification using "connected solutions," or connectivity between, electronic design automation software and test equipment will be described, illustrating how verification testing can be started earlier to help reduce risk by identifying performance issues early in the design cycle, when they are potentially easier and costly to implement.