教育部補助「行動寬頻尖端技術跨校教學聯盟第二期計畫 -- 行動寬頻網路與應用 -- 小細胞基站聯盟中心」 EPC核心網路系統設計 課程單元 04：LTE 通訊與協定 計畫主持人：許蒼嶺 (國立中山大學 電機工程學系) 授課教師：萬欽德 (國立高雄第一科技大學 電腦與通訊工程系)

LTE LTE However, LTE wireless interface A standard for mobile data communications technology An evolution of the GSM/UMTS standards However, LTE wireless interface Incompatible with 2G and 3G networks Must be operated on a separate wireless spectrum

History of LTE LTE was first proposed by NTT DoCoMo of Japan in 2004, and studies on the new standard officially commenced in 2005. The LTE standard was finalized in December 2008. The first publicly available LTE service was launched by TeliaSonera in Oslo and Stockholm on December 14, 2009 as a data connection with a USB modem. Samsung Galaxy Indulge: the world’s first LTE smartphone starting (February 10, 2011). On June 25th, 2013, Korea's SK Telecom announced the launching of LTE-Advanced services in Korea. [15] On June 26th, 2013, Samsung Electronics released an LTE-Advanced version of the Galaxy S4. [16] On July 18th, 2013, Korea's LG U Plus unveiled an LTE-Advanced network.[17] On August 18th, 2013, Philippines’ SMART Communications tests the LTE-Advanced network.[18] On November 5th 2013, two major carriers in the United Kingdom (Vodafone and EE) announced they would be holding LTE - A trials in the London area. On November 15th 2013, Telefonica and Vodafone have announced that they are testing LTE-Advanced in the German cities of Munich and Dresden

History of LTE (Cont’d) Initially, CDMA operators planned to upgrade to rival standards called UMB and WiMAX. But all the major CDMA operators have announced that they intend to migrate to LTE after all. Verizon, Sprint and MetroPCS in the United States Bell and Telus in Canada KDDI in Japan SK Telecom in South Korea China Telecom/China Unicom in China

LTE-Advanced (LTE-A) The evolution of LTE is LTE Advanced was standardized in March 2011. Services of LTE Advanced commenced in 2013.

Features of LTE Increase of capacity and speed of wireless data networks using new DSP and modulation techniques. Redesign and simplification of the network architecture to an IP-based system Reduced transfer latency compared to the 3G architecture

Major Requirements for LTE Higher peak data rates: 100 Mbps (downlink) and 50 Mbps (uplink) Improved spectrum efficiency: 2-4 times better compared to 3GPP release 6 Improved latency: Radio access network latency (user plane UE – RNC – UE) below 10 ms Significantly reduced control plane latency Support of scalable bandwidth: 1.4, 3, 5, 10, 15, 20 MHz Support of paired and unpaired spectrum (FDD and TDD mode) Support for interworking with legacy networks

Evolution of UMTS FDD and TDD

Data Transmission in LTE Downlink: Orthogonal Frequency Division Multiple Access (OFDMA) Uplink: Single Carrier FDMA (SC-FDMA): SC-FDMA: a new single carrier multiple access technique has similar structure and performance to OFDMA Advantage of SC-FDMA over OFDM: Low Peak to Average Power ratio (PAPR) : Increasing battery life

Evolution of Radio Access Technologies 802.16m 802.16d/e LTE (3.9G) : 3GPP release 8~9 LTE-Advanced : 3GPP release 10+

Introduction to OFDMA Downlink Frame Structure

What is OFDM

OFDM Signal Generation Chain OFDM signal generation is based on Inverse Fast Fourier Transform (IFFT) operation on transmitter side: On receiver side, an FFT operation will be used.

Difference between OFDM and OFDMA

OFDMA Time-Frequency Multiplexing

LTE – Spectrum Flexibility

Introduction to SC-FDMA Uplink Frame Structure

SC-FDMA Signal Generation Chain DFT “pre-coding” is performed on modulated data symbols Sub-carrier mapping allows flexible allocation of signal to available sub-carriers IDFT and cyclic prefix (CP) insertion as in OFDM. Each subcarrier carries a portion of superposed DFT spread data symbols, therefore SC-FDMA is also referred to as DFT-spread-OFDM (DFT-s-OFDM).

OFDM Signal Generation Chain OFDM signal generation is based on Inverse Fast Fourier Transform (IFFT) operation on transmitter side: On receiver side, an FFT operation will be used.

OFDMA (DL) vs. SC-FDMA (UL) 1/2 OFDMA: each sub-carrier only carries information related to one specific symbol SC-FDMA: each sub-carrier contains information of ALL transmitted symbols

OFDMA (DL) vs. SC-FDMA (UL) 2/2

Radio Procedure

LTE Initial Access

Cell Search in LTE (1/4)

Cell Search in LTE: Reference Signals (2/4)

Downlink Reference Signals (3/4)

Cell Search: Essential System Information (4/4)

LTE Initial Access

How to derive Information

LTE Initial Access

Indicating PDCCH Format

Uplink Physical Channels and Signals

Scheduling of Uplink Data

Acknowledging UL data packets on PHICH

Generic Frame Structure Allocation of physical resource blocks (PRBs) Scheduling at the 3GPP base station: Evolved Node B (eNodeB)

Frame Structure (DwPTS field) The downlink part of the special subframe Its length can be varied from three up to twelve OFDM symbols.

Frame Structure (UpPTS field) The uplink part of the special subframe It has a short duration with one or two OFDM symbols.

Frame Structure (GP field) The remaining symbols (not allocated to DwPTS or UpPTS) in the special subframe. Providing the guard period.

Resource Blocks for OFDMA One frame: 10 ms (with 10 subframes) One subframe: 1ms (with 2 slots) One slot: N Resource Blocks (6 < N < 110) The number of downlink resource blocks depends on the transmission bandwidth. One Resource Block: M subcarriers for each OFDM symbol M depends on the subcarrier spacing Δf The number of OFDM symbols in each block depends on both the CP length and the subcarrier spacing.

LTE Spectrum (Bandwidth and Duplex) Flexibility

LTE Downlink Channels The LTE radio interface: Various "channels" are used. Channels are used to segregate the different types of data and allow them to be transported across the radio access network in an orderly fashion. Physical channels: transmission channels that carry user data and control messages. Transport channels: the physical layer transport channels offer information transfer to Medium Access Control (MAC) and higher layers. Logical channels: provide services for the MAC layer within the LTE protocol structure. Physical Channel，乘載上層資訊並送出訊號給UE或EnodeB，簡單的說就是將Resourse Block(RB)分配的機制，規定每一個RB要做為什麼用途，會介紹這個是為了延續上篇介紹的主題。

LTE Downlink Channels Paging Control Channel Paging Channel Physical Downlink Shared Channel

LTE Downlink Logical Channels UE: User Equipment RRC: Radio Resource Control

LTE Downlink Logical Channels MBMS: Multimedia Broadcast Multicast Services

LTE Downlink Transport Channel

LTE Downlink Transport Channel

LTE Downlink Physical Channels

LTE Downlink Physical Channels

LTE Uplink Channels Random Access Channel CQI report Physical Uplink Shared Channel Physical Radio Access Channel

LTE Uplink Logical Channels

LTE Uplink Transport Channel

LTE Uplink Physical Channels

LTE Release 8 Key Features (1/2) High spectral efficiency OFDM in Downlink Single‐Carrier FDMA in Uplink Very low latency Short setup time & Short transfer delay Short hand over latency and interruption time Support of variable bandwidth 1.4, 3, 5, 10, 15 and 20 MHz

LTE Release 8 Key Features (2/2) Compatibility and interworking with earlier 3GPP FDD and TDD within a single radio access technology Efficient Multicast/Broadcast

Evolution of LTE-Advanced Asymmetric transmission bandwidth Layered OFDMA Advanced Multi-cell Transmission/Reception Techniques Enhanced Multi-antenna Transmission Techniques Support of Larger Bandwidth in LTE-Advanced

Symmetric and Asymmetric Transmission Bandwidth Voice transmission: UE to UE Asymmetric transmission Streaming video : the server to the UE (the downlink)

Layered OFDMA The bandwidth of basic frequency block is, 15 - 20 MHz Layered OFDMA comprises layered transmission bandwidth assignment (bandwidth is assigned to match the required data rate), a layered control signaling structure, and support for layered environments for both the downlink and uplink.

Coordinated Multi-Point Transmission/Reception (CoMP) The CoMP is one of the candidate techniques for LTE-Advanced systems to increase the average cell throughput and cell edge user throughput in the both uplink and downlink.

Enhanced Multi-Antenna Transmission Techniques In LTE-A, the MIMO scheme has to be further improved in the area of spectrum efficiency, average cell throughput and cell edge performances In LTE-A the antenna configurations of 8x8 in DL and 4x4 in UL are planned

Enhanced Techniques to Extend Coverage Area Remote Radio Requirements (RREs) using optical fiber should be used in LTE-A as effective technique to extend cell coverage

Support of Larger Bandwidth in LTE-Advanced Peak data rates up to 1Gbps are expected from bandwidths of 100MHz. OFDM adds additional sub-carrier to increase bandwidth

LTE vs. LTE-Advanced

Summary LTE-A helps in integrating the existing networks, new networks, services and terminals to suit the escalating user demands LTE-Advanced was standardized in the 3GPP specification Release 10 (LTE-A) and designed to meet the 4G requirements as defined by ITU