LTE (Long Term Evolution)

Agenday History and Overview y Network Architecture y Multiple Access Technique y Some PHY Layer Details y LTE Deployment

History and Overview LTE

Evolution of Wireless Systemsy 1st generation cellular: Analogy AMPS based on FM modulation + FDM

y 2nd generation cellular: Digitaly ANSI-54: American standard based on TDMA y GSM: ETSI standard (most successful wireless system

ever). y CDMA/ANSI-95: based on CDMA, North America, Japan, Korea.y 3rd Generation: All based on CDMAy UMTS: evolution of GSM based on WCDMA. Contains

HSDPA (3.5), HSPA(3.75), HSPA+(3.8). y CDMA-1x, CDMA-DO, CDMA-DV: North America, Japan, Korea.

LTEy Long Term Evolution (LTE): based on OFDM/OFDMA

(considered 3.9G )Evolution of UMTS. Still competing with WiMAX HSPA and HSPA+ dominant till 2014 LTE will start to be deployed in and after 2010. Defined by European Telecommunication Standardization Institute (ETSI) and the 3rd Generation Partnership Project (3GPP). y Specs available on the www.3gpp.orgy y y y y

What is LTE?

3G and LTE Roadmap

What is the driver?y The Anytime Anywhere Mobile Broadband becoming a necessity and

also fashion for many.y Data load more than voice load first time in 2007.

Why LTE?y Significantly increased peak data rates y Improved spectrum efficiency y Reduced latency y Scalable bandwidth 1.4 up to 20 MHz y Acceptable system and terminal complexity, cost and power

consumption y Compatibility with earlier releases and with other systems

Latency of Different Technologies

Requirement Peak data rate

Current Release (Rel-6 HSxPA) 14 Mbps DL / 5.76 Mbps UL 0.6 0.8 DL / 0.35 UL (bps/Hz/sector) 900 Kbps DL /150 Kbps UL 50 ms 2 sec 384 Kbps Up to 250 km/h No 5 MHz

LTE E-UTRA 100 Mbps DL / 50 Mbps UL

Spectral Efficiency

3-4x DL / 2-3x UL improvement 3-4x DL / 2-3x UL improvement 5 ms 50 ms 6-8x improvement Up to 350 km/h Yes Scalable

Averaged user throughput U-Plane Latency Call setup time Broadcast data rate Mobility Multi-antenna support Bandwidth

Network Architecture

Network Arch UMTS 3G p LTE

Network Architecture (3GPP R8)

y LTE mempunyai radio access dan core network yang

dapat:y mengurangi network latency dan meningkatkan

performansi sistem y menyediakan interoperability dengan teknologi 3GPP yang sudah ada dan non-3GPPy ENB (elvoved Node B)

peran dari RAN digantikan dengan ENB ini, shg dapat mengurangi OMS lebih sederhana

Simplified LTE Network Elements

eNodeBFungsi eNodeB adalah untuk Radio Resource Management: 1. Radio Bearer Control => mengontrol dan mengawasi pengiriman pesan yang dibawa oleh sinyal radio. 2. Radio Admission Control => berperan dalam Autentikasi atau mengontrol kelayakan pesan atau data yang akan melewati eNobeB 3. Connection Mobility Control => mengontrol/mengatur pengkoneksian sesuai keinginan UE 4. Dynamic Resource Allocation (scheduling)

Mobility Management Entity (MME)y Autentikasi user (dengan bantuan HSS) y Mengontrol fungsi signalling y Mengatur mobilitas control plane antara LTE dengan 2G atau 3G

access network y Memperbarui temporary ID (location update) y Memilih MME untuk handover dengan MME lain y Memilih SGSN untuk handover dengan jaringan akses 2G atau 3G

Home Subscriber Server (HSS)y Database utama yang juga berfungsi sebagai database pada

EPC. y Mirip seperti HLR pada 2G dan 3G

Serving Gateway Serving Gateway terdiri dr 2 bagian, yaitu

S-GW dan PDN-GW Serving Gateway (S-GW) untuk menghubungkan LTE dengan jaringan 3GPP PDN-GW untuk menghubungkan LTE dengan jaringan non3GPP

Multiple Access Technique

Single/Multi Carrier Systemsy Single carrier system y Signal representing each bit uses All of the available spectrum y Multicarrier system y Available spectrum divided into mutiple narrow bands y Data is divided into parallel data streams each transmitted on a separate band

What is Multipath?y More than one transmission path

between transmitter and receiver.y Fading :y Received signal is the sum

of many versions of the transmitted signal with varying delay and attenuation which cause either gains in the signal strength or deep fades.

Khaled Elsayed

OFDM and Multipathy How OFDM deals with multipath fading ?

Channel response in case of no multipath

Channel response in case of multipath i.e. the symbol knocked out

Only 2 subcarriers affected we lost just small subsets of the bits, they can be recovered by coding

OFDMAy Multiple access scheme based on OFDM and enjoys inherent

characteristics of immunity to inter-symbol interference and frequency-selective fading.

Khaled Elsayed

Multiuser DiversityOpportunistic Scheduling: Exploits the time-varying channel conditions and maximizes the system performance stochastically under a certain fairness constraint.

Comparing OFDMA and SC-FDMA

SC-FDMA in the uplinky LTE uses SC-FDMA in the uplink.why ? LTE uplink requirements differ from downlink requirements in several ways Not surprisingly, power consumption is a key consideration for handsets The high PAPR and related loss of efficiency associated with OFDM signaling are major concerns y (SC-FDMA) is well suited to the LTE uplink requirements

Peak-to-Average Power Ratioadalah perbandingan antara daya puncak sinyal dengan daya rata-ratanya.

Why does SC-FDMA have a low PAPR?

LTE Physical Layer

LTE Basic TechniquesTwo configurations exist:y Frequency Division Duplex: uplink and downlink have different bands y Time Division Duplex: uplink and downlink share same band. Duplexity

via allocation of subframes in the frame to either DL or UL.

FDD Frame Structure

d1

Slide 33 d1 add inthe notes that it is possible to have short and long prefic an dthus 6 or 7 symbols im the slotdboshra, 8/26/2008

Resource Blocks

LTE Key Parameters

Adaptive Modulation and Codingy Data is turbo coded and modulated using quadrature-phase shift keying

(QPSK), 16-QAM, or 64-QAM.y Depending on the channel condition, the best modulation technique is

selected to provide the most efficient spectral efficiency possibly with current signal-to-noise ratio on a per RB basis (a given user can see different parts of his allocations modulated/coded differently).y Codes with lower rates are used in poor channel conditions while codes

with higher rates are used in good channel conditions.

Scheduling in LTEy Very challenging issue: make the best

allocation to each user in frequency and time exploiting channel variations.y Retransmissions of HARQ.

Multiple Antenna MIMO menggunakan dua/lebih antenna dalam mobile phone

dan radio base station. Meningkatkan kecepatan transmisi secara substansial. sebagai contohnya, dua aliran data paralel, ke dan dari sebuah terminal, memberi pesat data dua kali lipat.

Whats Next?y ITU issued an invitation for technology proposal submissions for the IMT-Advanced

System in March 2008. y Very stringent requirements on rate and mobility. y Neither IEEE 802.16e nor LTE Rel. 8 satisfies IMT-Advanced requirements. y LTE-Advanced and IEEE 802.16m efforts were initiated to meet the targets True 4G Wireless

LTE-Advanced

Telkomsel Ujicoba LTE

y

LTE memang mulai menarik perhatian kalangan operator dunia. Suatu kajian yang dilakukan Wireless Intelligence menyebutkan bahwa paling tidak telah ada 115 operator yang tengah melakukan trial atau ujicoba teknologi LTE atau telah mengimplementasikan layanan komersial LTE.

y

Operator yang telah menyediakan layanan komersial LTE, antara lain TeliaSonera. Layanan saat ini tersedia di Stockholm dan Oslo. Di Amerika Serikat, Verizon berencana menggunakan frekuensi 700 Mhz dengan lebar 10 Mhz untuk pengembangan LTE. Sedangkan NTT Docomo, Jepang tengah melakukan deployment dengan menggunakan frekuensi 2 Ghz. (Republika.co.id)

LTE Deployment

Telia Sonera bekerjasama dengan Samsung mengembangkan Samsung LTE internet card yang telah dikomersialkan di

Huawei LTE Modem

Stockholm and Oslo.

Referensiy www.3gpp.org y www.LTEwatch.com y www.republika.co.idy Khaled Elsayed, LTE Tutorial

y E. Dahlman et al., 3G Evolution: HSPA and LTE for Mobile

Broadband, Academic Press, 2007