Technology Evolution And Performance Research Of UMB Systems' Physical Layer

Ultra Mobile Broadband system, supported by 3GPP2, is a kind of quasi fourth-generation wireless technology. UMB system is based on OFDMA technology, which is specifically for wireless mobile environments and optimized real-time applications. It inherits the adaptive coded modulation, HARQ, as well as QoS control mechanism from the EV-DO system, and is combined of CDMA, TDM, QOFDMA, LDPC and other advanced technologies. Multi-antenna technologies, based on MIMO, SDMA and Beamforming etc, are also introduced into UMB.On the aspects of the key technologies of UMB physical layer, the PBRI, with good performance of changing channel conditions, has a good effect on the resistance to fading of the transmission environment; Tail-biting encoding and LDPC can greatly avoid the occurrence of the error code in the transmission data, enhance the capacity of the signal on resistance to the noise interference in the transmission process and improve system reliability; Hierarchical modulation technology enables the operators to cover larger areas with the small base stations, and provide cost-effective high-quality services; And the capacity of the UMB systems has been greatly improved by using the multiple antenna technology, like the Closed-loop MIMO.The simulation platform is built by using MATLAB to assess the performance of the UMB systems'physical layer. In terms of AWGN channel, the PER will be quickly reduced below 10-3 by using convolutional codes and Turbo codes. In fading channel, the UMB systems'performance of FDD is slightly better than the TDD. Considering about the different versions of UMB protocol, the performance of the first edition is the worst. And the performance of the second edition is equal to the third edition. For the TDD version on December 2008, the physical layer performance is almost equal to the performance of FDD in the second edition. Compared with WiMAX, both in AWGN channel and fading channel, UMB systems have significant performance advantages.Compared with the existing 3G technologies, UMB systems have enormous improvement, even in the systems on the same generation, they also have advantages. As a beyond-3G mobile communication standard which is supported by 3GPP2, the key technologies in UMB are the development trends of the future mobile communication technologies. In the process of developing the next generation mobile communication systems by our country independently, the advanced technologies in UMB are worth learning and reference.