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Long Term Evolution (LTE) Technology Presented by GHANSHYAM MISHRA 11EC63R22 M.Tech, RF & Microwave Engineering IIT KHARAGPUR.
OUTLINE:Generation of wireless mobile technologiesTargets for LTELTE architectureLTE enabling technologies: OFDM MIMO antenna technology
Continued….Spectrum for LTE deploymentsComparative study of 3GPP LTE and Wi-MAXLTE network performanceLTE- AdvancedReferences
GENERATION OF WIRELESS MOBILE COMMUNICATIONGENERATION FEATURES THROUGHPUT TECHNOLOGY1G Analog 14.4 Kbps(peak) AMPS2G Digital , Narrowband, 9.6/14.4 Kbps TDMA(IS-136), GSM, Circuit switched data CDMA (IS-95)2.5 G Packet switched data 171.2 Kbps(peak) GPRS 20-40 Kbps3G Digital, broadband 3.1Mbps(peak) CDMA 2000, UMTS and packet data 500-700Kbps EDGE3.5 G > 2 Mbps Upto 3.6/7.2/14.4 HSPA Mbps(peak) 1-3 Mbps4G Digital broadband 100-300Mbps (peak) WIMAX,LTE-A packet , all IP , very 3.5 Mbps high throughput
Beyond 3G Evolutionary path beyond 3G ◦ – Mobile class targets 100 Mbps with high mobility ◦ – Local area class targets 1 Gbps with low mobility 3GPP is currently developing evolutionary/ revolutionary systems beyond 3G ◦ – 3GPP Long Term Evolution (LTE) IEEE 802.16-based WiMAX is also evolving towards 4G through 802.16m
MOTIVATION FOR 3G EVOLUTIONCURRENT GENERATION SUPER 3G Voice communication VoIP, high quality video conferencing SMS, MMS Video messaging Internet browsing Super-fast internet Downloadable games Online gaming with mobility Downloadable video High quality audio & video streaming No TV service Broadcast TV on-demand Peer-to-peer messaging Wide-scale distribution of video clips Mobile payment File transfer Many other innovative ideas
LTE Targets Peak data rate – 100 Mbps DL/ 50 Mbps UL within 20 MHz bandwidth. – Up to 200 active users in a cell (5 MHz) – Less than 5 ms user-plane latency Mobility – Optimized for 0 ~ 15 km/h. – 15 ~ 120 km/h supported with high performance. – Supported up to 350 km/h or even up to 500 km/h. Spectrum flexibility: 1.25 ~ 20 MHz Reduced capex/opex via simple architecture
LTE ARCHITECTURE Radio Interfaces Higher Data Throughput Lower Latency More Spectrum Flexibility Improved CAPEX and OPEX IP Core Network Support of non-3GPP Accesses Packet Only Support Improved Security Greater Device Diversity Service Layer More IMS Applications (MBMS, PSS, mobile TV now IMS enabled) Greater session continuity
LTE ARCHITECTURE Main logical nodes in EPC are: PDN Gateway (P-GW) Serving Gateway (S-GW) Mobility Management Entity (MME) EPC also includes other nodes and functions, such: Home Subscriber Server (HSS) Policy Control and Charging Rules Function (PCRF) EPS only provides a bearer path of a certain QoS, control of multimedia applications is provided by the IP Multimedia Subsystem (IMS), which considered outside of EPS E-UTRAN solely contains the evolved base stations, called eNodeB or eNB
LTE Enabling Technologies Two main technologies 1.Orthogonal Frequency Division Multiplexing (OFDM) 2.Multiple-Input Multiple-Output (MIMO) Antenna technology
OFDM We have a high rate (hence, large bandwidth) stream of modulation symbols Xk (ex. QAM) Needs to be transmitted on a frequency selective fading channel Stream Xk is divided into N low rate parallel sub- streams Bandwidth of each sub-stream is N times narrower Each sub-stream is carried by one subcarrier Received must restore each Xk without interference from current or previously transmitted sub-streams
OFDM Concept Transmitted OFDM Signal Received OFDM Signal
OFDM Concept guard X1 x e jω0 Serial to ParallelX1 XN-1 Tg Tb x Add jω + Guard e 1 xn 1 N −1 2π kn X N-1 x ωk = 2πk/N xn = N ∑ X k exp N e jωN −1 k =0 IFFT 0 1 Unused subcarriers Xk = 0 time N-1 frequency OFDM Symbol Ts =Tb+ Tg
OFDM Concept: OFDM modulation using IFFT Guard time (cyclic prefix) is added to protect against inter-symbol interference Guard subcarriers to protect against neighbor channels at both sides Some subcarriers are used as pilots for channel estimation After equalization, receiver performs FFT to retrieve back the stream Xk
OFDM ADVANTAGES OFDM is spectrally efficient IFFT/FFT operation ensures that sub-carriers do not interfere with each other. OFDM has an inherent robustness against narrowband interference. Narrowband interference will affect at most a couple of sub channels. Information from the affected sub channels can be erased and recovered via the forward error correction (FEC) codes. Equalization is very simple compared to Single-Carrier systems
OFDM ADVANTAGES OFDM has excellent robustness in multi-path environments. Cyclic prefix preserves orthogonality between sub-carriers. Cyclic prefix allows the receiver to capture multi- path energy more efficiently. Ability to comply with world-wide regulations: Bands and tones can be dynamically turned on/off to comply with changing regulations. Coexistence with current and future systems: Bands and tones can be dynamically turned on/off for enhanced coexistence with the other devices.
MIMO Signal transmitted from multiple antennas (Multiple In) Signal received by multiple antennas (Multiple Out) TX RX M N antennas antennas• Receiver combines the received signals and optimally combine energy from MxN channels• Two main types of MIMO Transmit Diversity Spatial Multiplexing
MIMO 2X2, Transmit Diversity Take M=2 and N=2 Diversity order 4
MIMO 2x2, Spatial Multiplexing ro = s o g o + s1 g 1 r1 = s o g 2 + s1 g 3 Purpose is to increase data rate (2x2 gives twice data rate) The 4 gains must be known at receiver Spatial multiplexing is a transmission technique in MIMO to transmit independent and separately encoded data signals from each of the multiple transmit antenna .
Spectrum for LTEdeployments An operator may introduce LTE in ‘new’ bands where it is easier to deploy 10 MHz or 20 MHz carriers. e.g. 2.6 GHz band(IMT Extension band) or Digital Dividend spectrum700, 800 MHz Or in re-farmed existing mobile bands e.g. 850, 900, 1700, 1800, 1900, 2100 MHz Eventually LTE may be deployed in all of these bands –and others later 2.6 GHz (for capacity) and 700/800 MHz (wider coverage, improved in-building) is a good combination LTE offers a choice of carrier bandwidths: 1.4 MHz to 20 MHz; the widest bandwidth will be needed for the highest speeds
Comparative study of 3GPP LTE and Wi-MAX WiMAX (Worldwide Interoperability for Microwave Access), is a wireless communication system that can provide broadband access on a large-scale coverage. It enhances the WLAN (IEEE 802.11) by extending the wireless access to Wide Area Networks and Metropolitan Area Networks.
Parameter WiMAX LTEDuplex method TDD FDD and TDDBandwidth 5 and 10 MHz 1.25, 3, 5, 10, 15 & 20 MHzFrame size 5 ms 10 ms with 10 sub-framesMultiplex Access DL OFDMA OFDMAMultiplex Access UL OFDMA SC-FDMAScheduling speed Every frame (5 ms) Every sub-frame (1 ms)Subcarrier spacing 10.9 kHz 15 kHzMaximum DL Data rate 46 Mbps (10 MHz band) 50 Mbps (10 MHz band)(SISO)Modulation QPSK, 16QAM, 64 QAM QPSK, 16QAM, 64 QAMDiversity MIMO up to 2x2 MIMO up to 4x4 TD & SM TD & SM
Advantages/disadvantages for WiMAX and LTE Parameter/Criterion WiMAX(+/-) LTE (+/-) Availability ++ - Migration costs - ++ Frequency band options + ++ Peak data rates + ++ Adaptive antenna systems + ++ UL performances + ++ DL performances + ++ Mobility + ++ Radio access modes + ++ (TDD&FDD) QoS provisioning ++ ++
LTE network deployments April 7, 2010: The number of mobile operators who have committed to deploy LTE advanced mobile broadband systems has more than doubled in the past year. There are now 64 operators committed to LTE network deployments in 31 countries, according to the Global mobile Suppliers Association (GSA)
LTE commercial networks -performance Signals Research Group conducted the first ever extensive independent drive test evaluation of a commercial LTE network, assessing the performance of the Telia SoneraLTE networks in Stockholm and Oslo, and reported to GSA: “While still in its infancy, commercial LTE networks in Stockholm and Oslo already outperform many fixed broadband connections, offering average data rates of 16.8Mbps (peak = 50Mbps) and 32.1Mbps (peak = 85Mbps) in 10MHz and 20MHz, respectively. Measured data rates would have been even higher if it had not been for the stringent test methodology, which focused almost entirely on vehicular testing.” Signals Research Group, LLC “Signals Ahead,” March 2010
LTE: some industry forecasts Maravedis: The number of LTE subscribers worldwide will pass 200 million in 2015 Strategy Analytics: the global LTE handset market will reach 150 million sales units by 2013 ABI Research: by 2013 operators will spend over $8.6 billion on LTE base stations infrastructure IDC: Spending on LTE equipment will exceed WiMAXequipment spend by end 2011, with worldwide LTE infrastructure revenues approaching USD 8 billion by 2014 Global mobile Suppliers Association (GSA): up to 22 LTE networks are anticipated to be in commercial service by end 2010, and at least 45 by end 2012 Gartner: long Term Evolution will be the dominant next- generation mobile broadband technology
FUTURE OF LTE LTE-Advanced (LTE-A) LTE-A shall have same or better performance than LTE Peak data rate (peak spectrum efficiency) Downlink: 1 Gbps, Uplink: 500 Mbps Peak spectrum efficiency Downlink: 30 bps/Hz, Uplink: 15 bps/Hz Same requirements as LTE for mobility, coverage, synchronization, spectrum flexibility etc
References: Erik Dahlman, Stefan Parkvall, Johan Sköld, Per Beming, "3G Evolution – HSPA and LTE for Mobile Broadband", 2nd edition, Academic Press, 2008, ISBN 978-0-12-374538-5. K. Fazel and S. Kaiser, Multi-Carrier and Spread Spectrum Systems: From OFDM and MC-CDMA to LTE and WiMAX, 2nd Edition, John Wiley & Sons, 2008, ISBN 978-0-470-99821-2. H. Ekström, A. Furuskär, J. Karlsson, M. Meyer, S. Parkvall, J. Torsner, and M. Wahlqvist, "Technical Solutions for the 3G Long-Term Evolution," IEEE Commun. Mag., vol. 44, no. 3, March 2006, pp. 38–45. “The Long Term Evolution of 3G” on Ericsson Review no.2, 2005. www.3gpp.org