ComNets Mobile Broadband Internet Access What Comes Next? Bernhard Walke ComNets, RWTH Aachen University www.comnets.rwth-aachen.de Work supported by German Ministry of Research & Education and EU-IST WINNER project
ComNets
Mobile Broadband Internet AccessWhat Comes Next?
Bernhard WalkeComNets, RWTH Aachen University
www.comnets.rwth-aachen.de
Work supported by German Ministry of Research & Education and EU-IST WINNER project
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008 2
Contents
1. Introduction: What Systems are present / expected?
2. Standardization of IMT-Advanced / 4G-Systems
3. Frequency Spectrum for IMT-Advanced
4. Main Characteristics of IMT-Advanced Systems
5. Conclusions
Download URL for papers referenced:
www.comnets.rwth-aachen.de/5+M5d637b1e38d.0.html
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008 3
Fixe
dW
alk
Vehi
cle
Bluetooth XDSL, CATV, Fiber
High Speed
VehicularRural
VehicularUrban
Pedestrian
Nomadic
Fixed urban
Indoor
Personal Area
DECTPHS
GSMGPRS
CDMA-1x
EDGE
UMTS(W-CDMA)
CDMAEV DORev. O/A
CDMAEV DORev. B
HSDPA
WLAN(IEEE 802.11x)
HSPA LTE
(SAE)
UMB
IEEE802.16m
UMB-Evolution
User data rate
Mobility / Range
0.1 1 10 100 1000 Mbps
LTE-Advanced
EDGE-11GERAN
Evolution
IEEE802.16e
WiMAX
IEEE802.16d
1) non-official name; 2) System Architecture Evolution
1)2)
1)
Source: Takagi/Walke: Spectrum Requirements Planning in Wireless Communications, J. Wiley 2008
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008 4
Contents
1. Introduction: What Systems are present / expected?
2. Standardization of IMT-Advanced / 4G-Systems
3. Frequency Spectrum for IMT-Advanced
4. Main Characteristics of IMT-Advanced Systems
5. Conclusions
Download URL for papers referenced:www.comnets.rwth-aachen.de/5+M5d637b1e38d.0.html
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008 6
ITU-R
SystemsGeneration
3GPP
3GPP2
IEEE 802
1)
2)
2003/4 2005/6 2007/8 2009/10 2011/12
IMT-2000 IMT-Advanced
3G 4G
WCDMAUMTS/FDD/TDD
WCDMAHSDPA Rel. 5 OFDM/SC-FDMA
LTE Rel. 8
cdma 20001xEV-DO
OFDM/SC-FDMALTE-Advanced
cdma 2000EV-DO Rev A
cdma 2000EV-DO Rev B
UMB/OFDMUMB Evolution
OFDM.16 Fixed (2004)
OFDMA.16e Mobile
WiMAX WAVE I
OFDMAWAVE II Rel. 1.0
OFDMA.16e,j; WAVE Rel. 1.x
WCDMAHSPA EV Rel. 6/7
OFDMA.16m; WAVE Rel. 2.0
B3G
1) Overlay to GSM; 2) Overlay to CDMA-1x; 3) expected, but not specified, so far; 4) non-official name;(currently in question)
3) 4)
4)
3)
Source: Takagi/Walke: Spectrum Requirements Planning in Wireless Communications, J. Wiley 2008
Roadmap of IMT–Advanced Candidate Systems
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008 7
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011
2.0
1.5
1.0
0.5
2.5
Bps/Hz
Spe
ctra
l E
ffici
ency
Spectral Efficiency
100
10
1
0.1
1000
Mbps
Pea
k D
ata
Rat
e
Peak Data Rate
0.01
GPRSCDMA
EDGE
CDMA 2000
1xEVDORev.0
UMTS
1xEVDORev.A
HSDPA
1xEVDORev.B
HSUPAWiMAX
UMBLTE
WiMAX
IMT-AdvancedIMT-2000
Narrowband Data Middleband Data Broadband Data2G 2.5G 3G B3G 4G
Multiple Antenna
Contribution
Source: Takagi/Walke: Spectrum Requirements Planning in Wireless Communications, J. Wiley 2008
Spectral Efficiency and Peak Data Rate Evolution in Time
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008 8
IMT-Advanced Candidate Systems
• 3GPP-LTE II / LTE + / LTE-Advanced• Ultra Mobile Broadband (UMB) 3GPP2
/QUALCOMM (possibly: no system proposal)
• SUPER 3G (Japan)• 3G+ (Korea)• TD-SCDMA Ev. (China)• IEEE 802.16m (based on 802.16e, j) • IEEE 802.11n (ad-hoc component for cellular) • WINNER+ (Europe) LTE-Advanced
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008 9
Contents
1. Introduction: What Systems are present / expected?
2. Standardization of IMT-Advanced / 4G-Systems
3. Frequency Spectrum for IMT-Advanced
4. Main Characteristics of IMT-Advanced Systems
5. Conclusions
Download URL for papers referenced:www.comnets.rwth-aachen.de/5+M5d637b1e38d.0.html
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008 10
• WRC-07 identified new spectrum for IMT
• Changed IMT-2000 spectrum identifications to IMT
• Work has started on spectrum utilization
500 600 700 800 900 1000400
470862450
1700 1800 1900 2000 2100 2200
20252010
2110 21701710
2300 2400 2500 2600 2700 2800 2900
2690
3400 3500 3600 3700 3800 3900 4000
698 960
Previous IMT-2000
Identified at WRC’07
Bands identified by WRC-07 for IMT Systems
Simplified diagram!
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008 11
Spectrum Requirements Calculation
• ITU-R M.1036 “Spectrum Estimation Methodology for IMT-Advanced Systems”: 450 MHz needed.464 MHz identified by WRC-07 in Nov. 2007
April 2008
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008 12
Contents
1. Introduction: What Systems are present / expected?
2. Standardization of IMT-Advanced / 4G-Systems
3. Frequency Spectrum for IMT-Advanced
4. Main Characteristics of IMT-Advanced Systems
1. MAC protocol proposed by ComNets
2. Layer-2 Relays for IMT-Advanced Systems proposed by ComNets
5. Conclusions
Download of papers referenced:
www.comnets.rwth-aachen.de/5+M5d637b1e38d.0.html
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008 13
Main Characteristics of IMT-Advanced Systems
• Orthogonal Frequency Division Multiplex (OFDM) to share the medium
• Orthogonal Frequency Division Multiple Access (OFDMA) for medium access
• Periodic MAC frame (known from RACE Project MBS and BMBF Project ATMmobil)
• Antenna Arrays at Base and Mobile Terminal
• Interference • Coordination / Cancellation / Avoidance
• Relay Enhanced Cells (known from Project IST-WINNER
• Simplified Network Operation (Radio Access Router enhanced by mobility support)
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008 14
OFDMA Subchannels and Resource Elements
• Transmission capacity as a Matrix
• Allocation of orthogonal Resource Elements possible
• Multi dimensional REs– Time, Frequency– Code, Space
• Constraints– Parallel transmission/
reception on different subchannels not possible
• Medium access control (MAC) is based on REs
optimal size of REs?
2-dimensional resource grid (time/frequency)
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008 15
Contents
1. Introduction: What Systems are present / expected?
2. Standardization of IMT-Advanced / 4G-Systems
3. Frequency Spectrum for IMT-Advanced
4. Main Characteristics of IMT-Advanced Systems
1. MAC protocol proposed by ComNets
2. Layer-2 Relays for IMT-Advanced Systems proposed by ComNets
5. Conclusions
Download of papers referenced:
www.comnets.rwth-aachen.de/5+M5d637b1e38d.0.html
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008 16
Medium Access Control (MAC) by central Base Station
MAC concept• Centralized resource
request/grant scheme• Used in IEEE 802.16 (2004),
proposed for IEEE 802.11nFrame structure• Beacon (Broadcast)
– Announcement of Resource Elements
• Random Access Channel– Association, resource
requests, ACKs• Resource Element
– Transmission of data burst (PDU train)
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008
BMBF/ATMmobil MAC-Protokoll wurde Std. ETSI/BRAN HiperLAN2
• DSA++ Protokoll: ComNets Patent Walke/Petras 1995– Dynamische zentrale Kapazitätszuweisung auf Slot Basis– Rahmenbasiert, variable MAC Rahmenlänge– Unterstützung unterschiedlicher Dienstgüteanforderungen
Signalisierungsperiode SignalisierungsperiodeSignalisierungsperiode
PCtrl-PDURQCH-PDUs
Downlink ATM-Zellen Uplink ATM-Zellen
Zeit
TransceiverUmschaltzeiten
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008
WiMAX MAC Protocol is identical to ETSI/BRAN/HiperMAN, that is derived from HiperLAN2
• Periodic MAC frame, starting with Frame Control Header (FCH)
• Contention phase (initial access, bandwidth request)
• Uplink (UL) and downlink (DL) phase
• Phases consist of burst
• Maps describing frame schedule
• Downlink: Which station should receive the burst
• Uplink: Which station is allowed to send in the burst
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008 19
0 2 3 4 5 6 0 1 2 3 4 5 61
time
time slot(1 OFDMA symbol)
1200
sub
chan
nels
100
chun
ks
signaling overhead scheduled
resources
TTI = 500 μs (7 x 66.6 μs + 6 x 4.687 μs + 1 x 5.208 μs)
1/6 for pilots
66.6 μsCyclicprefix
1 chunk =12x6=72sub-symbolstime
f
LTE TTI Frame (MAC Frame)Further developed DSA++ protocol for OFDMA systems
TTI = transmissiontime interval
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008 21
Contents
1. Introduction: What Systems are present / expected?
2. Standardization of IMT-Advanced / 4G-Systems
3. Frequency Spectrum for IMT-Advanced
4. Main Characteristics of IMT-Advanced Systems
1. MAC protocol proposed by ComNets
2. Layer-2 Relays for IMT-Advanced Systems proposed by ComNets
5. Conclusions
Download of papers referenced:
www.comnets.rwth-aachen.de/5+M5d637b1e38d.0.html
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008 22
Cell Capacity vs. Distance is Inverse to the Needs
Range of broadband base station is limited– high attenuation at high frequencies – limited transmit power (EIRP limits)– Unfavourable radio propagation
conditions, e.g., in urban area# of BS required increases with increased carrier frequency to cover given areaHigh Capital and Operations ExpensesHigh cost/bit transmitted High data rate available close to AP only
Under constant user density: o Number of users proportional to
distance d from Base Stationo Cell capacity per area element differs
from what is requested by userso Technology trend worsens situation
Actual Available Capacity vs. Requested Capacity
Available
Requested by users2005
Cell border
Cap
city
/A
rea
Ele
men
t
2010
Location of the Base Station
Distance d
Sources: B. Walke, H. Wijaya, D.C. Schultz: Relays in Infrastructure-based Future Mobile Radio Networks, VTC 2006 Spring, Melbourne, AustraliaT. Irnich, D.C. Schultz, R. Pabst, P. Wienert: Capacity of a Relaying Infrastructure for Broadband Radio Coverage of Urban Areas. Proc. 10th WWRF meeting, New York, 10/2003
Users at distance d
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008 23
Relay Enhanced Cell (REC) A cell complemented by Fixed Relay Nodes (FRN)
• Layer-2 Relays in REC – Save cost for wired backbone
access – Full flexibility of relays positioning – enlarge the coverage area – Increase capacity at cell border– balance capacity/area element– reduce transmission power / co-
channel interference• Relays
– Support fast network rollout– Allow outdoor to indoor service– Serve shadowed areas in REC– Exploit macro diversity–will be mass products
Capacity Optimisation
Area Optimisation
Coverage of shadowed areas
One-hop Cell
AP
FRN
Source: B. Walke, H. Wijaya, D. Schultz: Relays in Infrastructure-based Future Mobile Radio Networks. VTC 2006 Spring, Melbourne, Australia
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008
Relaying in Time Domain – Subframe ConceptComNets Patent Walke/Esseling 2000
• Subframe Concept: Enables multi-hop operation for relaying in time domain
• Multiple FRS’s are served by one BS• FRSs’ MAC frame are embedded to BS’s MAC frame• Duration of FRS MAC frame may depend on traffic load
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008 25
Layer-2 Relays in IMT-Advanced
• Layer 2 (Decode-and-Forward) relays are part of an IMT-Advanced systems, as specified by WINNER II
• Relay enhanced RRM technologies – Relays and multi-antenna technologies– Different modulation and coding schemes on
relay and access link– Plug and play network roll out
• Tree topology, self-configuring nodes– Self healing: On demand re-organisation of the
network topology– On demand meshing within REC
• Cooperative relaying as an option for capacity improvement
Cooperative Relaying
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008 26
Inter/intra Cell Resource ManagementResource Separation in Frequency Domain(OFDMA)
full
band
wid
th
Resources used in one cell
one TTI frame(500 us)
Base stationRelay
© 2008 ComNets ComNets Neubau Einweihung, Nov. 21, 2008 27
Mobile Broadband Networks will base on Relay Enhanced Cells
Conclusion• IMT-Advanced spectrum allocated • IMT-Advanced Systems
– OFDMA: resources in time, frequency and space– Coordination needed: intra- and inter-cell
• Standardization in progress• Relay enhanced cells are part of it
(IEEE802.16j) – extend cell range – increase throughput at cell edge– Reduce impact of signal shadowing
• Relays save Telco infrastructure cost