Downlink base transmit station modulator in WCDMA system

Abstract

The WCDMA system is one of the main modulations used in the third generation mobile communication. In this paper, we present a new modulation structure for downlink base transmit station in WCDMA system. The new architecture has the following functional blocks: VQ separation, channel mapping, spreading and scrambling, SCH code generation, 48-tap pulse shaping filter, gain and snm, and timing generator. Implementation data shows that our approach works well in the complex spreading spec” system LINTRODUCTION According to the statistics from ITU investigation, there were 5 billion users of mobile phone in the late 2000’s. It’s about a half of the users of the wired phone. Some prediction also shows that the users of the mobile phone will be more than the nsers of the wired phone, and will be popular in 2005. Moreover, the combination of wireless communication and consumer electronic is a trend in the future. Therefore, offering a wideband and high-speed environment with multiple services is an important requirement for future wireless communication systems. The 3G mobile communication system is emphasized in the functions of multimedia services. The transmitting speed is from 384 Kbps to 2 Mbps. The leading system technologies are W-CDMA, the UTRA (W-CDMA and TD-CDMA), and the CDMAZOO. Since these three systems are so different, the organizations of 3GPP (3rd Generation Partnership Project) and 3GPP2 (3rd generation Partnership Project 2) are sponsored to coordinate these standards and make them interoperable. This paper presents a new architecture of downlink base transmit station (BTS) modulator in WCDMA system. For the simulation results, we find that our architecture can achieve the requirement of 3GPP. Section 2 introduces the 3GPP downlink BTS modulator specification. Section 3 introduces the transmitting method of the modulator. Section 4 presents the function blocks of the modulator and their interfaces. Section 5 gives the simulation results. Finally, in section 6, we give some concluding remarks.