| HSPA+is the evolution of HSPA with backward compatibility.In order to address the characters of large amount of data flow and low latency,HSPA+ has taken in some bandwidth enhancement techniques, including MIMO technology and high order modulation,rendering the maximum rate for the single-carrier system on the downlink to 42 Mbps,and four-carrier systems on the downlink to 168Mbps. This thesis discussed the principles of receiver in HSPA+ downlink, simulated and analyzed its performance based on vs2008.The introduction of high order modulation in HSPA+ results in the system being sensitive to the result of the multipath search and channel estimation. For the condition of this problem, this paper puts forward a new modified multipath search algorithm, which adds smooth processing and improves the strategies of selecting effective paths in order to improve the accuracy of searching, and reduce the possibility of missed selection, eventually improve the overall performance of the receiver.Because the traditional one-slot weighted channel estimation algorithm can not effectively restrain the noise and track the time-varying channel, the performance is poor in low speed or high speed environment. This paper puts forward an advanced IIR filter algorithm that can adaptively trace the variation of the wireless channels, using the simplified statistical method, selecting suitable filter coefficients to make the channel estimation mean-square error least, not only stay the same with the change of the channel, also can effectively restrain the noise, to achieve the optimal performance.Because the signal caused by MIMO and hign-level modulation suffers from ISI through multi-path channel, it limits the performance of the traditional RAKE receiver. In this paper, we introduce a GRAKE receiver suitable for HSPA+ system, compared to RAKE receiver; it adds the additional noise finger, uses the characters of the correlation between noise and signal fingers, and adopts proper combining coefficient, in order to restrain some of the interference, improve the receiving signal-to-noise ratio. In addition, this paper provides GRAKE receiver under the condition of the application of precoding techniques or space time transmit diversity.Based on MIMO of precoding techniques in HSPA+ and adaptive coding modulation technology in HSPA, this paper puts forward a new CQI/PCI measurement algorithm used in HSPA+ system, which measures the SINR of HS-PDSCH, completes the look-up table method and follows the maximum throughput volume rule to predict the scheme of coding modulation, the number of streams transferred and the precoding matrix suitable for wireless channel to make the final system to achieve the best performance.In order to validate the receiving algorithm performance in HSPA+, we built a HSPA+ downlink simulation platform.Simulation results demonstrate that the performance of GRAKE receiver is obviously superior to RAKE receiver. At the same time, the modified multi-path detection algorithm has 0.6dB gain than traditional algorithm in the VA channel, and the adaptive channel estimation algorithm based has 1dB gain than one-slot average algorithm in the VA channel. Finally, based on the GRAEK receiver and the modified algorithm of multi-path detection and channel estimation, with use of the CQI/PCI measuring algorithm, the simulation of throughputs for downlink in AWGN, PA and VA channel in HSPA+ system is completed and the performance can satisfy the requirements of design index.All the algorithms mentioned above are applied to HSPA+ related projects.The simulation platform built in this paper provides the support for the HSPA+ related projects in my laboratory.Both fixed-point simulation and hardware implementation test results have the simulation platform as a performance reference. |
