11.07.2015 Views

Multi-Carrier and Spread Spectrum Systems: From OFDM and MC ...

Multi-Carrier and Spread Spectrum Systems: From OFDM and MC ...

Multi-Carrier and Spread Spectrum Systems: From OFDM and MC ...

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3GPP Long Term Evolution (LTE) 221User PlaneControl PlaneRadio ResourceControl (RRC)Packet Data Convergence Protocol(PDCP)Radio Link Control(RLC)Medium Access Control(MAC)Physical Layer(PHY)Figure 5-4User <strong>and</strong> control plane protocol stackRRC are admission control, h<strong>and</strong>over management, QoS management, terminal stationmeasurement reporting <strong>and</strong> control, MBMS control, <strong>and</strong> paging.Packet Data Convergence Protocol (PDCP)The main functions of the PDCP for the user plane are IP header compression, transferof user data, <strong>and</strong> ciphering. At the control plane the corresponding functions are transferof control data <strong>and</strong> ciphering.Radio Link Control (RLC)Segmentation <strong>and</strong> reassembly of packets from higher layers as well as error correctionthrough ARQ are main functions of the RLC. Additionally, flow control between theeNodeB <strong>and</strong> the mobile terminal is h<strong>and</strong>led by the RLC.Medium Access Control (MAC)The MAC is responsible for the scheduling in the up- <strong>and</strong> downlink, error correctionthrough hybrid ARQ (HARQ), adaptive modulation, resource <strong>and</strong> power assignment, <strong>and</strong>antenna mapping.Physical Layer (PHY)Main functions of the physical layer are coding, modulation, <strong>and</strong> multiple antenna transmission(MIMO). The LTE physical layer is explained in detail in the following sections.5.2.5 Downlink Transmission SchemeThe transmission scheme of the LTE downlink is <strong>OFDM</strong> with a cyclic prefix. It has beenshown in Chapter 1 to 4 that besides the robustness of <strong>OFDM</strong> in frequency selective

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