Research of Data Processing Technology in LTE_FDD E-NodeB Uplink Physical Layer
|School||Harbin Engineering University|
|Course||Signal and Information Processing|
|Keywords||Long Term Evolution Channel Estimation Frequency Domain Equalization Sounding Reference Signal Frequency Dependent Scheduling Technology|
As LTE been determined the candidate technologies for4G by ITU（InternationalTelecommunications Union）, it has drawn a growing concern and research. Within20MHzlimited spectrum bandwidth, LTE can reach50Mbps uplink peak rate and downlink100Mbpspeak rate. With the features of fast transfer rates, High system reliability and low equipmentcomplexity, this technology gets the favor of most of the Western main operators and hasbroad market prospects and practical value.This article is divided into three aspects: data processing of LTE_FDD basebandphysical layer, channel estimation and frequency domain equalization technology and uplinkfrequency dependent scheduling technology based on SRS (SRS hopping and SRS PLtechnology). First, paper gives data processing flow of LTE_FDD baseband physical layer,and analyzes the principles and methods of symbol-level processing and bit-level processing.Bit-level processing includes CRC checksum encoding, code block segmentation, Turbochannel coding, rate matching and channel interleaving; symbol-level processing includesscrambling, modulation mapping, transmission pre-coding sub-carrier mapping andSC-FDMA symbol (OFDM modulation). Given frame and sub-frame structure of LTE_FDD,LTE_FDD channel estimation methods based on the ZC sequence is brought up. After therealization of channel estimation method in LTE_FDD commercial systems introduced, itscore algorithm is elaborated in detail, including: LS estimation, time shift estimation andinterpolation technology. The performance of zero equalizer and the MMSE equalizerin inAWGN, low-speed channel and high-speed channel is analyzed on the basis of channelestimation result, and SNR to BLER curves of the three equalizers are given under threedifferent channels. Decision feedback equalizer is first introduced to LTE_FDD system,which effectively improves the anti-interference performance of LTE system.In order to choose a better quality channel band for UE uplink service transmission, souplink frequency dependent scheduling technology is particularly important.Uplink frequencydependent scheduling technology based on the SRS is studied in this paper. The SRSfrequency hopping technology and the SRS the PL technology is introduced in commercialsystems to solve power-constrained problem. The SRS Receiving and processing process isanalysed in detail on the base station side, and measurement algorithms for SRS single-user, two yards sub-users and four yards sub-user are proposed in commercial system. In actualcommercial systems, the performance based on SRS frequency-selective technology isstudied and tested under frequency-selective channel (AWGN channel, EPA5channel andEPA10channel) with the use of channel analog instrument. With the UE uplink traffic data,applicable level is finally obtained based on the SRS frequency-selective technology underdifferent channels.Finally, the hardware implementation and software implementation ofentire baseband physical layer are given. The detailed flow chart and division schematicdiagram of the DSP core are introduced as well.