ALCATEL-LUCENT LTE DEEPDIVE ON LTE TDD
3GPP FREQUENCY BANDS FOR TDD E-UTRA Operating Band
Uplink (UL) operating band BS receive UE transmit FUL_low
33
1900 MHz
34
2010 MHz
35
1850 MHz
36
1930 MHz
37
1910 MHz
38
2570 MHz
39
1880 MHz
40
2300 MHz
41
2496 MHz
42
3400 MHz
43
3600 MHz
– – – – – – – – – – –
– FUL_high
Downlink (DL) operating band BS transmit UE receive FDL_low
1920 MHz
1900 MHz
2025 MHz
2010 MHz
1910 MHz
1850 MHz
1990 MHz
1930 MHz
1930 MHz
1910 MHz
2620 MHz
2570 MHz
1920 MHz
1880 MHz
2400 MHz
2300 MHz
2690 MHz
2496 MHz
3600 MHz
3400 MHz
3800 MHz
3600 MHz
Main 3GPP Bands used for TD-LTE
– – – – – – – – – – –
–
Duplex Mode
FDL_high
1920 MHz
TDD
2025 MHz
TDD
1910 MHz
TDD
1990 MHz
TDD
1930 MHz
TDD
2620 MHz
TDD
1920 MHz
TDD
2400 MHz
TDD
2690 MHz
TDD
3600 MHz
TDD
3800 MHz
TDD
FDD band
LTE GLOBAL BAND UTILIZATION Europe, Africa & Middle East
Americas
New 700Mhz band combined with GSM/WCDMA & CDMA bands refarming
Band 2
Band 5
China & APAC
GSM/UMTS refarming of 1800, 900, digital divide 800 & 2600 BWA bands
Band 1
North America
Band 4
TDD band
CDMA & GSM / WCDMA refarming and BWA new bands
Europe China
Band 3 Band 7
Band 7
Middle east & India Band 3
Band 8
Band 12
Band 13
Band 14
Band 17
Band 23
Band 25
CALA
Band 26
Band 27
Band 2
Band 29
Band WCS
Band 3
Band 4
Band 7
Band 12
Band 13
Band 17
Band 27
Band 28
Band 41
Future bands
Band 1 Band 3 Band 5
Band 7 Band 13
Band 38
Band 20 Band 33
Band 40
Africa
Band 35 Band 38
Band 3
Band 40
Band 7
Band 42 Band 43
Band 9 Band 11
Band 19
Band 21
Band 41 XGP ver
Band 1
APAC
Band 7 Band 38 Band 38
Japan
Band 1
Band 39
Band 3
Band 40
Band 5
Band 7
Band 41
Band 13
Band 28
Band 38
Band 40
Band 20
TD-LTE Devices are already operation over 1.9/2.3/2.6 GHz band s
Band 44
TD-LTE DEVICE ECOSYSTEM HIGHLIGHT CMCC IS LEADING THE WAY •In 2012, 50K+ TD-LTE devices deployed across 15 China Mobile networks (LST + Hong Kong) operating at 1.9/2.3/2.6GHz bands and supporting GSM/TD-SCDMA interworking. •For Q4 2013, China Mobile is committed to purchase and deploy 1.2 million units supporting dual-mode e.g. FDD+TDD.
DRIVERS
GLOBAL MARKET Australian, Brazilian, Russian and Middle East carriers are deploying 100K+ of devices for Broadband Wireless Access Service already at aggressive price level.
SOLUTION At the beginning of TD-LTE, ALU acquired equity in small chipset suppliers to facilitate their on-going developments with early time to market and close support for ALU
LEADERSHIP ECOSYSTEM Recently ALU has provided Infra equipment and support to a Smartphone vendor leader to facilitate their entry into TDD. ALU is actively engaged with a large number of chipset and commercial device vendors.
China Mobile commitment to drive the ecosystem and their requirements for global devices (multi-mode/multi-bands) are boosting the proliferation of low cost TD-LTE devices and early adoption in many areas outside china (e.g. Russia, ME, Sprint…)
MARKET
SOLUTION
3GPP LTE: FDD
TD-LTE
LTE-FDD One Standard One Access Scheme Channel BW Frame Duration Ratio (DL:UL)
3GPP TS 36.xxx
TD-LTE (set of LTE specs)
• OFDMA for DL • SC-FDMA for UL
1.4MHz, 3MHz, 5MHz, 10MHz, 15MHz, 20MHz 10ms 1:1
5ms, 10ms 5ms (2:6), (4:4), (6:2), (3:5) 10 ms (6:3), (7:2), (8:1)
LTE TDD IS TRULY GLOBAL MANY COMBINING FDD AND TDD
2013 is the year of TDD takes off 25% of total LTE subs will be TDD by 2017 21 commercial LTE TDD networks in 17 countries and 39 planned 10 commercial LTE FDD+TDD networks Sept, 2013 - GSA
3GPP LTE PHYSICAL LAYER FUNDAMENTALS FRAME STRUCTURE: FDD & TDD
•The basic type 1 LTE frame has an overall length of 10 ms. •This is then divided into a total of 20 individual slots.
D D F
LTE Subframes consist of two slots
D D T
•The frame structure for the type 2 frames used on LTE TDD is somewhat different. •The 10 ms frame comprises two half frames, each 5 ms long. •The LTE half-frames are further split into five subframes, each 1ms long.
3GPP LTE FRAME STRUCTURE TD-LTE FRAME & SPECIAL SUBFRAME CONFIGURATION Frame Configuration (0 to 6) •Frame Configuration have 7 types to fulfill different requirements of DL and UL.
Special Subframe Configuration (0 to 8) “S” denotes a special subframe 3 fields R S
User Data DwPTS
Primary Sync. Signal
GP
Secondary Sync. Signal
UpPTS
• Downlink pilot time slot (DwPTS): used for downlink synchronization, DwPTS can contribute to downlink throughput, if it has more than 3 OFDM symbols. • Uplink pilot time slot (UpPTS) zone: used by eNode B to determine the received power level, • Guard Period: it ensures the transmission of UE without interference between UL and DL
3GPP LTE - EVOLVED UTRA LTE TDD VS LTE FDD FOR CELLULAR COMMUNICATIONS LTE TDD Paired Spectrum
Harwdware Cost
Channel reciprocity
LTE FDD
Does not require paired spectrum as both transmit and receive occur on the same channel.
Requires paired spectrum with sufficient frequency separation to allow simultaneous Tx and Rx.
Lower cost as no duplexer is needed to isolate the transmitter and receiver. As cost of the UEs is of major importance because of the vast numbers that are produced,
Duplexer is needed and cost is higher.
this is a key aspect.
Channel propagation is the same in both directions which enables transmit and receive to use on set of parameters.
Channel characteristics different in both directions as a result of the use of different frequencies
It is possible to dynamically change the UL and DL capacity ratio to match demand
UL/DL capacity determined by frequency allocation set out by the regulatory authorities. It is therefore not possible to make dynamic changes to match capacity. Regulatory changes would normally be required and capacity is normally allocated so that it is the same in either direction.
UL / DL asymmetry
3GPP LTE - EVOLVED UTRA LTE TDD VS LTE FDD FOR CELLULAR COMMUNICATIONS (CONT’D) LTE TDD
Guard period / guard band
Discontinuous transmission
Cross slot interference
LTE FDD
Guard period required to ensure uplink and downlink transmissions do not clash. • Large guard period will limit capacity. • Larger guard period normally required if distances are increased to accommodate larger propagation times.
•Guard band required to provide sufficient isolation between uplink and downlink. •Large guard band does not impact capacity.
Discontinuous transmission is required to allow both uplink and downlink transmissions. This can degrade the performance of the RF power amplifier in the transmitter.
Continuous transmission is required.
Base stations need to be synchronized with respect to the uplink and downlink transmission times. If neighbouring base stations use different uplink and downlink assignments and share the same channel, then interference may occur between cells.
Not applicable
3GPP LTE - EVOLVED UTRA LTE TDD VS LTE FDD FOR CELLULAR COMMUNICATIONS (CONT’D) LTE TDD Application/ Services
LTE FDD
TDD is best suited for bursty, asymmetric traffic, such as Internet or other data centric services.
FDD is is best suited for applications, such as voice, that generate symmetric traffic
Much of the world’s traffic is moving towards IPbased technology. A primary reason for IP’s popularity is that it is packet based, which is a very efficient way to transmit data, and increasingly voice (VoIP). IP Traffic Very Bursty Highly Asymetric
‘Always-on’ 50% upstream, 50% downstream scenario that characterises FDD systems.
Efficiently use of spectrum for asymmetrical traffics.
FDD cannot be used in environments where the service provider does not have enough bandwidth to provide the required guard band between transmit and receive channels.
TDD-FDD COVERAGE COMPARISON 2.6GHz, 10MHz channel
Urban
Rural
m k
Kbps at cell edge
Kbps at cell edge More 25% bigger cell radius with FDD
More 30% bigger cell radius with FDD
FDD is more efficient when coverage limites
TDD-FDD PEAK RATE COMPARISON
FDD Channel size (MHz)
- 10(DL)+10(UL)
TDD - 20 (DL+UL) - 2x2 MIMO
Downlink
Uplink
- 2x2 MIMO
- CFI=1
- CFI=1
- ‘S’ SF format 7 (10:2:2)
- MU-MIMO 16QAM (2 users)
TDD frame format
When traffic is really unbalanced in Downlink favor TD-LTE is more efficient FDD is a bit more efficient for a symmetrical traffic TDD is more efficient for asymetrical throughputs
TDD-FDD AVERAGE RATE COMPARISON
FDD Channel size (MHz)
- 10(DL)+10(UL)
TDD - 20 (DL+UL) - 2x2 MIMO
Downlink
Uplink
- 2x2 MIMO
- CFI=3
- CFI=3
- ‘S’ SF format 7 (10:2:2)
- 1x2 SISO 16QAM
TDD frame format
When traffic is really unbalanced in Downlink favor, then TD-LTE is more efficient
FDD is a bit more efficient for a symmetrical traffic TDD is more efficient for asymetrical throughputs
3GPP LTE FRAME STRUCTURE
subframe
f
subframe
LTE Frame ( 10ms ) subframe
…
first 1..3 OFDM symbols reserved for L1/L2 control signaling Subcarrier Subframe (1ms)
subframe Physical Resource Block (PRB) = 14 OFDM Symbols x 12 Subcarriers This is the minimum allocation unit in LTE
one OFDM symbol 15 kHz
PRB Reference signals (pilots)
3GPP LTE ANTENNA PORT CONFIGURATIONS(1/2) LTE specifications define several transmission mode with specifics DL reference signals Single antenna, 2 or 4 antennas Antenna port 0 up to antenna port 3: SISO, Diversity, CL and OL MIMO R0
TS36 36.213 Rel 8 defined 7 DL transmit mode
t r o p a n n e t n a e n O
R0
TM1: Single-antenna port; port 0
TM2: Transmit diversity, based on spacefrequency block coding (SFBC)
R0
R0
R0
0
l
6 l
TM5: Multi-user MIMO
TM6: Closed-loop Rank=1 precoding
TM7: Single-antenna port; port 5
l
6
R0
R1
R0
R1
R1
s t r o p a n n e t n a
R0
R0
R1
R0
R0
TM4: Closed-loop spatial multiplexing
0
Resource element ( k,l )
TM3: Open-loop spatial multiplexing
R0
o w T
R0
R0 l
R0
l
R0
0
l
6 l
R1
Reference symbols on this antenna port
R1
0
R0
l
6
l
R0
Not used for transmission on this antenna port
R1
0
R1 l
6 l
R1
0
l
6
R1
R2
R3
s t r o p a n n e t n a r
R0
u o F
R0
R1
R0
R0
R0 l
0
R1
R0 l
6 l
even-numbered slots
0
l
Antenna port 0
6
l
0
R2
R1
R2
R3
R1
R2
R1
odd-numbered slots
R1
l
6 l
even-numbered slots
0
l
odd-numbered slots
Antenna port 1
6
l
0
R3
R3 l
6 l
even-numbered slots
0
l
odd-numbered slots
Antenna port 2
6
l
0
l
even-numbered slots
6 l
0
l
odd-numbered slots
Antenna port 3
6
3GPP LTE RELEASE 8 ANTENNA PORT CONFIGURATIONS(2/2) –
Single
virtual antenna port 5 (can be used for Beam Forming in TDD) R5
R5
R5
R5 R5
R5
R5
R5 R5
R5
R5
l
MBMS
R5
l
0
6 l
even-numbered slots
using virtual antenna port 4
l
0 odd-numbered slots
Antenna port 5
Physical Mulicast channels (PMCH) iso PDSCH PMCH shall not be transmitted in SF 0 and 5 on carrier supporting mix of data Specific RS pattern R4 R4
R4
R4 R4
R4 R4
R4
R4 R4
R4
R4 R4
R4
R4
R4 R4
l
0
R4
l
5 l
even-numbered slots
0
l
odd-numbered slots
5
6
TRANSMISSION MODE SUMMARY Transmission Mode
Name Reference
Description
1
Single Port Antenna
2
Transmit Diversity
3
Open Loop Spatial Multiplexing
Potential benefits over Tx Div in high SINR rich scattering environments
4
Closed Loop Spatial Multiplexing
Potential benefits over CL R1 & Tx Div in high SINR rich scattering environments Potential benefits over OL SM at low speeds
5
Multi-User MIMO
6
Closed Loop Rank=1 Pre-coding
7
Single Layer Beamforming
Used for SISO & SIMO antenna configs Typically better than SM in low SINR Robust to high vehicle speed Lower signaling overhead than SM
Close-loop precoding for linear array or diversity array Typically better than SM in low SINR Potential benefits over Tx Div at low speeds Lower signaling overhead than SM Single layers per user (single-user MIMO). TM is to support BF for Rel-8 devices
This
8
Dual Layer Beamforming
9
Seamless Switching Between SU and MU MIMO (up to rank 8)
•Spatial Multiplexing supported •Up to 2 layers per user (single-user MIMO). This TM is to support BF for Rel-9 (and later) devices •Up to 8 layer transmission in single-user •Up to 4 layer transmission for multi-user MIMO. •Frequency selective PMI. •Precoding per subband basis
