mc-04 lte and beyond
DESCRIPTION
Perkembangan teknologi mobileTRANSCRIPT
LTE, WiMAX and 4G
Mobile Communication and Mobile Computing
Prof. Dr. Alexander Schill
http://www.rn.inf.tu-dresden.de
Department of Computer Science Institute for System Architecture, Chair for Computer Networks
LTE: Characteristics
• LTE = Long Term Evolution • European implementation of IMT (International Mobile
Telecommunications) by ETSI (European Telecommunication Standards Institute)
• Packet oriented propagation only • High data rates
- Up to 300 Mbit/s Downlink - Up to 75 Mbit/s Uplink
• Flexible frequency assignment - About 40 frequency ranges - Varying frequency blocks (1.4, 3, 5, 10 and 20 MHz)
• small latency of 5ms between mobile phone and conventional telephone network
• optimized for travelling speeds of up to 15 km/h (but up to 500km/h possible with reduced quality)
2
LTE – User Equipment
• Examples of LTE-enabled devices - iPhone, Samsung Galaxy LTE,
Samsung LTE Stick • Five device categories
Category 1 2 3 4 5
Peak data rate Mbit/s
DL 10 50 100 150 300
UL 5 25 50 50 75
RF bandwidth 20 MHz
ModulaAon QPSK, 16QAM QPSK, 16QAM, 64QAM
2 Rx diversity Assumed in performance requirements
2x2 MIMO Not supported
Mandatory
4x4 MIMO Not supported Mandatory 3
LTE: Frequency bands
• Germany (currently) - 5 bands: 800 MHz, 900 MHz, 1800 MHz, 2000 MHz, 2600MHz - Rural Areas - 800 MHz
- Urban Areas - 800 MHz - 1800 MHz -> partially reassignment from GSM
- 2600 MHz for crowded areas in cities (stations, shopping malls, etc.)
• USA: 700MHz, 1700MHz and 2100 MHz • Europe: 800 MHz and others • Bands 700, 800, 1800 and 2600 MHz will potentially
allow world wide roaming in the future
4
LTE: German frequency bands
• frequency spectrum of the digital dividend: better building penetration & propagation features > higher range
• frequency spectrum of the IMT extension band: Enough blocks for 20 MHz bandwidth > Higher data rate
5
Duplex gap* 12 MHz 820 MHz 832 MHz
5 MHz frequency block
(72 Mhz) 790 MHz 862 MHz
10 x 5 MHz blocks uncoupled 2570 MHz 2620 MHz
5 MHz frequency block
(190 Mhz) 2500 MHz 2690 MHz
* The Duplex gap is meant as a fallback position for wireless production technology.
LTE – Reference Architecture
UE eNodeB S-GW P-GW
MME
LTE - Uu S1-U S5/S8
S1-MME S11
HSSS6a
PCRF
Gx
SGiPSTN
eUTRAN Core Network
• NodeB + RNC (3G) merged into `evolved NodeB´ (eNodeB) • Core network - Serving Gateway (S-GW) - Mobility Management Entity (MME) - PDN (Packet Data Network) Gateway (P-GW) - Home Subscriber Server (HSS) - Policy Control and Charging Rules Function (PCRF) 6
Tasks of eNodeB: Overview
• eNodeB manages one or several cells
• Major tasks: - IP header compression - Encryption - Radio resource
management - Connectivity to core
network - Bearer management - UE mobility
Core Network
E-UTRAN
eNodeB
eNodeB
eNodeB
MME S-GW MME S-GW
comm. between eNodeBs
signaling to MMEs bearer path
7
LTE: TDD and FDD
• two versions of LTE provide solutions for coupled/uncoupled frequency blocks
• transmitted signals divided into subframes (time units of 1 ms) • FDD (Frequency division duplex) -separated frequency blocks for UL/DL • TDD (Time division duplex) – one frequency block alternately used for
UL/DL: - Downlink subframes, Uplink subframes and Special Frames - “Special Frame” = one subframe for each switching from down to up
link; contains DwPTS (Downlink Pilot Timeslot), GP (Guard Period – avoids overlay of sent and received messages) and UpPTS (Uplink Pilot Timeslot)
8
subframe = 1 millisecond
0 5 4 3 2 1 6 9 8 7
Uplink (UL)
Downlink (DL)
0 5 4 3 2 1 6 9 8 7
Uplink (UL)
Downlink (DL)
Special Frame
DwPTS Guard Period
UpPTS
FDD
TDD
LTE: Use of OFDM for Multiplexing
LTE transmission is based on OFDM (Orthogonal frequency-division multiplexing)
• in OFDM data is distributed over a large number of closely spaced orthogonal subcarriers - (two subcarriers are orthogonal if the maximum amplitude of one
subcarrier is reached while the other subcarriers amplitude is zero) - Subcarriers modulated with conventional modulation scheme (QAM)
• Pro: robust against interference because interference on subcarrier does not influence the whole frequency band, improved spectrum efficiency and lower bandwidth demand with OFDM
• Con: expense for coding and decoding and therefore the power consumption increases with the number of subcarriers
9
OFDM with 3 subcarriers
f f
FDM with 3 subcarriers
LTE: Specific enhancements of OFDM
LTE uses specific enhancements of OFDM with a focus on efficient simultaneous access of multiple users:
OFDMA (Orthogonal frequency-division multiple access)
for Down Link • subsets of subcarriers are assigned to individual users, so
simultaneous (lower data rate) transmissions are enabled for several concurrent users on the same subcarrier
SC-FDMA (Single Carrier FDMA) for Up Link • multiple access on the same carrier realized by insertion
of user-specific coefficients by the sender before Fourier transformation, and respective decoding by the receiver (roughly comparable to CDMA). More energy-efficient for battery-driven mobile devices.
10
LTE Bearer
UE P-‐GWeNodeB S-‐GW
UL-TFT
Application/service layer
UL-‐TFT
DL-TFT
DL-TFT
Radio bearer S1 bearer S5/S8 bearer
RB-‐ID <-‐-‐> S1-‐TEID S1-‐TEID <-‐-‐> S5/S8-‐TEID
• Different QoS requirements of applications (VoIP, browsing, file download) are mapped to bearers
• Bearers cross multiple interfaces, each part is individually mapped to lower layer bearer with own bearer id
• Each node manages binding between bearer ids • Packet filters (Traffic Flow Templates (TFT)) assign IP packets to bearers
(e.g. based on IP header information and TCP port numbers) 11
Standardized QoS class identifier for LTE
QCI Resource Type
Priority Packet Delay Budget(ms)
Packet Error Loss Rate
Example Service
1 GBR 2 100 10-‐2 ConversaAonal voice
2 GBR 4 150 10-‐3 ConversaAonal video (live streaming)
3 GBR 5 300 10-‐6 Non-‐conversaAonal video (buffered streaming)
4 GBR 3 50 10-‐3 Real-‐Ame gaming
5 Non-‐GBR 1 100 10-‐6 IMS signaling
6 Non-‐GBR 7 100 10-‐3 Voice, video (live streaming), interacAve gaming
7 Non-‐GBR 6 300 10-‐6 Video (buffered streaming)
8 Non-‐GBR 8 300 10-‐6 TCP-‐based (for example, WWW, e-‐mail), chat, FTP, p2p file sharing, progressive video and others
9 Non-‐GBR 9 300 10-‐6
GBR … guarantied bit rate, IMS … IP Multimedia Subsystem 12
LTE Interworking
UE E-UTRAN S-GW P-GW
MME
LTE - Uu S1-U S5/S8
S1-MMES11
3G-SGSN
S3 S4
non-3GPP networks (CDMA2000, WiMAX,…)
UTRAN(GSM, UMTS)
• Interworking and mobility with other 3GPP defined networks as well as non-3GPP defined networks
• Service Gateway (S-GW) is mobility anchor for other 3GPP networks
13
LTE Advanced
• Specified as LTE Release 10 • Improved performance
- Data rate up to 1 GBit/s - End-to-end delay 20 – 30 ms
• Enhancements - Carrier aggregation - up to 5 * 20 MHz -> 100MHz - Possible in contiguous and non-contiguous spectrum allocations
- Multiple Input, Multiple Output (MIMO) - Up to 4 LTE antennas in LTE devices to use MIMO also for Uplink - Base stations can be equipped with up to 8 antennas
- Support for relay node base stations - Additional intermediate base stations - Improve signal quality at cell borders
- Support of low power nodes for picocells and femtocells (extremely small cells) for crowded areas
14
WiMAX / IEEE 802.16
• WiMAX: Worldwide Interoperability for Microwave Access, standardized by IEEE 802.16 and WiMAX-Forum (large industry consortium)
• IEEE 802.16 FBWA (Fixed Broadband Wireless Access) initially was an alternative for broadband cable services like DSL; frequency range: 10-66 GHz, in assumption of LOS (line of sight)
• Enhancement IEEE 802.16a; frequency band: 2-11 GHz, NLOS (non line of sight)
• Enhancement IEEE 802.16e: MBWA (Mobile Broadband Wireless Access); frequency band: 2-6 GHz, NLOS
• Enhancement IEEE 802.16m: Mobile High Speed Communication; projected for up to 1 Gbit/s
15
WiMAX/IEEE 802.16: overview
Standard 802.16 802.16a 802.16e 802.16m Spectrum, GHz 10-66 2-11 2-6 2-6
LOS-condition LOS NLOS NLOS NLOS Bit rate, MBit/s 32-134 up to 75 up to 100 up to 1000
(theoretical) Range, km up to 5
up to 50 (cellular)
2-5 2-5
Channel bandwith, MHz
20, 25 and 28
Variable: 1,5–20
1,5 -20 1,5-20
Modulation QPSK, 16QAM, 64QAM
OFDM, QPSK,
16QAM, 64QAM
OFDM, QPSK, 16QAM, 64QAM
OFDM, QPSK, 16QAM, 64QAM,
128QAM
16
(N)LOS – (Non) Line-of-Sight
WiMAX: Frequencies worldwide
17
For Germany especially: 3,41-3,452 GHz and 3,51-3,552 GHz
WiMAX: Modulation
18
• WiMAX: strong dependency of applicable modulation technique on effective channel capacity, spectrum efficiency, range, signal-noise-ratio:
• BPSK – Binary Phase Shift Keying
• QPSK – Quadrature Phase Shift Keying
• 16QAM – Quadrature Amplitude Modulation
• 64QAM – Quadrature Amplitude Modulation
(typical example distribution (percentage) of users in different coverage areas)
802.16 Medium Access
• TDMA (Time Division Multiple Access) - Each communication channel gets fixed slot for data
transmission • DAMA (Demand Assigned Multiple Access) - 2 Phases: - Reservation: every station tries to acquire slot for
each transmission phase (collision possible) - Data transmission: within reserved slot guaranteed
collision free transmission • Duplex connection - FDD (Frequency Division Duplex): simultaneous use of
different frequencies - TDD (Time Division Duplex): Switching between up-
and downlink on the same frequency
19
WiMAX: Cellular backbone
20
Network
Point to Point Backbone
Point to Multipoint
WiMAX cell
UMTS cell
802.16 PHY 802.16
OFDM-PHY e.g Gigabit
Ethernet
1) Last Mile (point to point) or 2) Point to Multipoint network • Base Station (BS) is the central point for the
Mobile Stations (MS) • Sending in Downlink-direction: Broad-, Multi-, Unicast • Connection of a MS to BS is characterized via Channel ID (CID),
- Channel id gives the possibility for the BS to receive multicast messages
802.16 Network topologies
21
MS/BS
MS/BS
BS
MS
MS MS MS
Network
802.16 Network topologies
3) Mesh network • MS can communicate directly • Mesh BS: connected with a network outside the mesh • other differentiation
- neighbor: direct connection to a node - neighborhood: all other neighbors - extended neighborhood: remote neighborhoods
22 Mesh MS
Mesh BS
Mesh MS Mesh MS
Mesh MS
Mesh MS Mesh MS Network
MBWA (Mobile Broadband Wireless Access); 802.20
• Working Group 802.20 originated from 802.16
- goal: Specification of PHY and MAC for Packet-based MBWA-System
- Should close the gap between WLAN and slower but highly mobile networks (UMTS)
- But never reached operational state, so practically not relevant anymore
• Summary: Overall judgement of WiMAX - Interesting approach especially for last mile in remote
neighborhoods with weakly developed infrastructure
- However, even in such areas, 3G and 4G are emerging, and also due to lack of flexible and affordable end devices, WiMAX is strongly declining 23
UMTS/HSPA/HSPA+ WiMAX MBWA LTE (advanced)
Mobility Handover, Roaming ---------------- Handover, Roaming, Mobile IP ---
Max Speed 300 km/h 120 km/h 300 km/h 500 km/h
Switching type circuit and packet ---------------- Packet switching ----------------
Peak data rates Down Link
2/14,4/28 Mbit/s (5MHz channel)
365 Mbit/s (2x 20MHz channel, variations)
– 100 - 300 Mbit/s (1.4-20 MHz channel)
Cell sizes pico(1)-, micro(2)-, macro(3)-cells variable
pico(1)-, micro(2)-, macro(3)-cells
pico(1)-, micro(2)-, macro(3)-cells
QoS End-to-end QoS Different classes
End-to-end QoS Different classes
End-to-end QoS
End-to-end QoS Different classes
Scalability ---------------- variable data rate ~ Multiple users per BS --------------
Air Interface CDMA adaptive Modulation MIMO
OFDM(A), adaptive Modulation MIMO
OFDM Adaptive Modulation
OFDM, SC-FDMA adaptive Modulation MIMO
Security AES AES, X.509 AES SNOW 3G
Technology comparison
24
(1)<100m, (2)~500m, (3)>1km
4G Characteristics: Summary
• high mobility Ú Handover, Roaming, velocity up to more than 300 km/h
• switching technique Ú pure packet switching • integrated multi-media-services Ú VoIP, TVoIP, VoD,
Streaming • high data rate (up to 1Gbit/s) Ú even at high mobility
should be like DSL • Size of cell Ú variable and scalable • QoS Ú prioritization of specific multimedia data • scalability Ú available and reliable with many users • air interface Ú OFDM (better spectrum efficiency) • security Ú up to date standards (e.g. AES) • Extension / integration of UMTS, LTE and WLAN
approaches
25
Technology comparison 3G to 4G
26
LTE (3G) LTE Advanced (4G)
Peak data rate Down Link (DL) 300 Mbit/s 1 Gbit/s
Peak data rate Up Link (UL) 75 Mbit/s 500 Mbit/s
Transmission bandwidth DL 20 Mhz (max.) 100 Mhz
Transmission bandwidth UL
20 Mhz (max.)
40 Mhz (requirements as defined by ITU)
Coverage Full performance up to 5km
Same as LTE requirement. Should be optimized or deployed in local areas/micro cell environments.
Scalable bandwidths 1.4, 3, 5, 10 and 20 MHz 20-100 MHz
Scalability variable data rate Multiple users per BS
variable data rate Multiple users per BS
Capacity 200 active participants per cell at 5 MHz
3 times higher than that in LTE
Summary: Data rates and mobility
27
High-speed
/Wide-area
Medium-speed
/Urban area
Walking
/Local area
Standing
/Indoors
3G/
IMT 2G
Source: www.3g.co.uk
Mobility
0.1 1 10 100 200 1000 Bitrate, MBit/s
LTE 4G/
LTE advanced
Wireless LANs
Personal area access
Some further readings
• Eds.: Sesia, S., Toufik, I., Baker, M.: LTE – The UMTS Long Term Evolution – From Theory to Practice, Whiley, 2009
• LTE: www.gsmworld.com www.ltemobile.de www.apwpt.org
• WiMAX technology: www.wimaxforum.org
• IEEE web sites for 802.16 and 802.20: grouper.ieee.org/groups/802/16/ and …/802/20
28