0
1
3GPP Long Term Evolution
Overview and Technical Specifications1
All rights reserved © 2008, Faculty of Engineering @ Cairo University
2
AGENDA:
 Introduction
 LTE technologies
 LTE ra...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
3
Introduction
LTE vs. HSPA Evolution
 Among differ...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
4
Introduction
LTE Design Targets
 Capabilities.
 ...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
5
LTE Design Targets
Capabilities
 Downlink and upl...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
6
LTE Design Targets
Capabilities
 At least 200 mob...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
7
Introduction
LTE Design Targets
 Capabilities.
 ...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
8
LTE Design Targets
System Performance
 System per...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
9
LTE Design Targets
User Throughput
9
All rights reserved © 2008, Faculty of Engineering @ Cairo University
10
LTE Design Targets
Mobility
 Maximum performance...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
11
LTE Design Targets
Coverage
 It is the maximum d...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
12
LTE Design Targets
Enhanced MBMS
 MBMS is define...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
13
Introduction
LTE Design Targets
 Capabilities.
...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
14
LTE Design Targets
Deployment Related Aspects
 D...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
15
LTE Design Targets
Deployment Scenarios
 Two pos...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
16
LTE Design Targets
Interaction With Other RATs
 ...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
17
LTE Design Targets
Spectrum Flexibility & Deploym...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
18
LTE Design Targets
Spectrum Flexibility & Deploym...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
19
LTE Design Targets
Example
 An example is the IM...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
20
LTE Design Targets
Example
20
All rights reserved © 2008, Faculty of Engineering @ Cairo University
21
LTE Design Targets
Spectrum Flexibility & Deploym...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
22
Introduction
LTE Design Targets
 Capabilities.
...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
23
LTE Design Targets
Architecture & Migration
23
All rights reserved © 2008, Faculty of Engineering @ Cairo University
24
AGENDA:
 Introduction
 LTE technologies
 LTE r...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
25
LTE Technologies
 Equalization against radio-cha...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
26
LTE Technologies
Equalization
 Three main equali...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
27
LTE Technologies
Time Domain Equalization
 A fil...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
28
LTE Technologies
Time Domain Equalization
 Match...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
29
LTE Technologies
Time Domain Equalization
 Minim...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
30
LTE Technologies
Frequency Domain Equalization
 ...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
31
LTE Technologies
Frequency Domain Equalization
31
All rights reserved © 2008, Faculty of Engineering @ Cairo University
32
LTE Technologies
Frequency Domain Equalization
 ...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
33
LTE Technologies
Other Techniques
 Decision-Feed...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
34
LTE Technologies
Flexible BW Assignment
 Orthogn...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
35
LTE Technologies
Flexible BW Assignment
 As TDMA...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
36
LTE Technologies
Flexible BW Assignment
 This wi...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
37
LTE Technologies
DFT-Spread OFDM
 SC-OFDMA combi...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
38
LTE Technologies
DFT-Spread OFDM
 DFT/IDFT combi...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
39
LTE Technologies
PAR Reduction
39
All rights reserved © 2008, Faculty of Engineering @ Cairo University
40
LTE Technologies
DFTS-OFDM Demodulator
40
All rights reserved © 2008, Faculty of Engineering @ Cairo University
41
LTE Technologies
DFTS-OFDM Demodulator
 Equaliza...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
42
LTE Technologies
User Multiplexing
42
Equal BW as...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
43
 With a raised cosine shaping instead of zero
pa...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
44
LTE Technologies
DFTS-OFDM With Spectrum Shaping
...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
45
 Constant or almost constant amplitude in line
w...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
46
AGENDA:
 Introduction
 LTE technologies
 LTE r...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
47
LTE Radio Interface
Protocol Stack
47
 Packet Da...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
48
LTE Radio Interface
Protocol Stack
48
 Radio Lin...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
49
LTE Radio Interface
Protocol Stack
49
 Medium Ac...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
50
LTE Radio Interface
Protocol Stack
50
 Medium Ac...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
51
LTE Radio Interface
Protocol Stack
51
 Medium Ac...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
52
LTE Radio Interface
Protocol Stack
52
 Physical ...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
53
 LTE_DETACHED
 Used @ power up when the mobile ...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
54
 LTE_ACTIVE
 Mobile terminal is active with tra...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
55
 LTE_IDLE
 Low activity state to reduce battery...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
56
AGENDA:
 Introduction
 LTE technologies
 LTE r...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
57
LTE Physical Layer
Supported Channels
 Downlink ...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
58
LTE Physical Layer
Service provided to upper laye...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
59
LTE Physical Layer
Overall Time Domain Structure
...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
60
LTE Physical Layer
Overall Time Domain Structure
...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
61
LTE Physical Layer
Overall Time Domain Structure
...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
62
LTE Physical Layer
Overall Time Domain Structure
...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
63
LTE Physical Layer
Downlink Transmission scheme
...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
64
LTE Physical Layer
Downlink Transmission scheme
...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
65
LTE Physical Layer
Downlink Transmission scheme
...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
66
LTE Physical Layer
Downlink Transmission scheme
...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
67
LTE Physical Layer
Downlink Transmission scheme
...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
68
LTE Physical Layer
Downlink Transmission scheme
...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
69
LTE Physical Layer
Downlink Transmission scheme
...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
70
LTE Physical Layer
Downlink Transmission scheme
...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
71
LTE Physical Layer
Downlink Transmission scheme
...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
72
LTE Physical Layer
Downlink Transmission scheme
...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
73
LTE Physical Layer
Uplink Transmission scheme
 T...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
74
LTE Physical Layer
Uplink Transmission scheme
 T...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
75
LTE Physical Layer
Uplink Transmission scheme
 T...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
76
LTE Physical Layer
Uplink Transmission scheme
 T...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
77
LTE Physical Layer
Uplink Transmission scheme
 T...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
78
LTE Physical Layer
Uplink Transmission scheme
 U...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
79
LTE Physical Layer
Uplink Transmission scheme
 R...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
80
LTE Physical Layer
Uplink Transmission scheme
 R...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
81
AGENDA:
 Introduction
 LTE technologies
 LTE r...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
82
 Physical-layer blocks which are dynamically con...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
83
 Physical-layer blocks which are dynamically con...
84
84
LTE Physical Layer
Transport Channel Processing
 Multiplexing and channel
coding
 Different channels may undertake...
8585
LTE Physical Layer
Transport Channel Processing
 CRC attachment
 Cyclic Redundancy Check (CRC) is calculated and
ap...
 CRC attachment
 DL-SCH and MCH CRC parity length is L = 24
 BCH CRC parity length is L = 16
 DL-CCH CRC parity length...
 CRC attachment
 UL-SCH: The parity bits are computed and attached to the UL-SCH
transport block by setting L to 24 bits...
 Code Block Segmentation
 The input bit sequence to the code block segmentation is denoted by,
where B > 0. If B is larg...
 Channel Coding
 There are two convolution coding types used with LTE
 Tail biting convolution coding
 Turbo coding
 ...
 Channel Coding
 Tail biting convolutional coding
 A tail biting convolutional code with constraint length 7 and coding...
 Channel Coding
 Turbo coding
 The scheme of turbo encoder is a Parallel Concatenated Convolutional
Code (PCCC) with tw...
 Channel Coding
 DL-SCH and MCH LTE uses turbo code rate 1/3
 BCH LTE uses tail biting convolutional code rate 1/3
 DL...
 Channel Coding
 UL-SCH: Turbo coding with rate 1/3
 UL-CCH: not specified yet according to release 8, Sep07
 Three fo...
 Rate matching
 Rate matching for DL-SCH and UL-SCH is defined per coded
block and consists of interleaving the three in...
 Rate matching
 Sub-block interleaver
 The bits input to the block interleaver are denoted by where D is the
number of ...
 Rate matching
 Sub-block interleaver
 The bits input to the block interleaver are denoted by where D is the
number of ...
 Rate matching
 Sub-block interleaver
 For Perform the inter-column permutation for the matrix
based on the pattern tha...
 Rate matching
 The output of the block interleaver is the bit sequence read out column by column
from the inter-column ...
 Rate matching
 Bit collection, selection and transmission
9999
LTE Physical Layer
Transport Channel Processing
99
All r...
 Code Block concatenation.
 Simply this block concatenate the different code blocks (C code block) that are
segmented be...
 Downlink modulation and antenna coding
101101
LTE Physical Layer
Transport Channel Processing
101
All rights reserved © ...
 Downlink modulation and antenna coding
 Scrambling
 Block of bits delivered by the code block concatenation is multipl...
 Downlink modulation
 The downlink data modulation transforms a block of scrambled bits to
corresponding block of comple...
 Antenna mapping
 Layer mapping and pre-coding
 Antenna Mapping jointly processes the modulation symbols
corresponding ...
 Antenna mapping
 Layer mapping and pre-coding
 The layer mapping provides de-multiplexing of the modulation
symbols of...
 Antenna mapping
 Example: spatial multiplexing
 In case of spatial multiplexing there is, in the general case, two cod...
 Antenna mapping
 Example: spatial multiplexing
107107
LTE Physical Layer
Transport Channel Processing
107
All rights re...
 Resource mapping
 Maps the symbols to be transmitted on each antenna to the resource elements of
the set of resource bl...
 Resource mapping
109109
LTE Physical Layer
Transport Channel Processing
109
All rights reserved © 2008, Faculty of Engin...
 Resource mapping
 Downlink L1/L2 control signaling
 L1/L2 control channels are mapped to the first (up to three) OFDM ...
 Uplink modulation and antenna coding
 Scrambling
 UL-SCH & UL-CCH use UE specific scrambling sequences prior to
modula...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
112
 Modulation
 UL-SCH supports all modulation sc...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
113
 Transform pre-coding ( UL-SCH only)
 Each blo...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
114
 Mapping to physical resources
 UL-SCH
 The m...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
115
 Mapping to physical resources
 UL-CCH
 The m...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
116
AGENDA:
 Introduction
 LTE technologies
 LTE ...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
117
Physical Layer Procedures
Cell search
 Cell sea...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
118
Physical Layer Procedures
Cell search
 LTE prov...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
119
 Primary and secondary synchronization signals:...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
120
 Time/frequency structure of synchronization
si...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
121
 Secondary synchronization signal generation:
...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
122
 First step
 The mobile terminal uses the prim...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
123
 Second step:
 Observe pairs of slots where th...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
124
 Products of second step:
 The terminal can re...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
125
 After the first step, the primary synchronizat...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
126
 Initial cell search
 For initial cell search,...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
127
 Neighbor-cell search
 Neighbor-cell search ha...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
128
 Neighbor-cell search (contd.):
 In the case o...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
129
AGENDA:
 Introduction
 LTE technologies
 LTE ...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
130
 Random access is the process by which a termin...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
131
Physical Layer Procedures
Random access
All rights reserved © 2008, Faculty of Engineering @ Cairo University
132
 Step 1: Random access preamble transmission
 ...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
133
 Step 1: Random access preamble transmission
 ...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
134
 Step 1: Random access preamble transmission
 ...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
135
 Step 1: Random access preamble generation
 Th...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
 Step 1: Random access preamble generation
 Preamb...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
137
 Step 1: Random access preamble detection
 Sam...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
138
 Step 1: Random access preamble detection
Physi...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
139
 Step 2: Random access response
 In response t...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
140
 Step 2: Random access response
 In case the n...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
141
 Step 3: Terminal identification
 Before user ...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
142
 Step 4: Contention resolution
 The network tr...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
143
AGENDA:
 Introduction
 LTE technologies
 LTE ...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
144
 Paging is used for network-initiated connectio...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
145
 A Discontinuous cycle is defined, which allows...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
 The paging message includes the identity of the
te...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
147
AGENDA:
 Introduction
 LTE technologies
 LTE ...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
 Downlink power control determines the energy
per r...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
 Uplink power control:
 Uplink power control contr...
All rights reserved © 2008, Faculty of Engineering @ Cairo University
 Downlink power control:
 The eNodeB determines th...
Upcoming SlideShare
Loading in...5
×

6558145 lte-final-v1

92

Published on

Published in: Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
92
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
7
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Transcript of "6558145 lte-final-v1"

  1. 1. 1 3GPP Long Term Evolution Overview and Technical Specifications1
  2. 2. All rights reserved © 2008, Faculty of Engineering @ Cairo University 2 AGENDA:  Introduction  LTE technologies  LTE radio interface  LTE physical layer  Frame structure  Physical layer processing  Physical layer procedures 2
  3. 3. All rights reserved © 2008, Faculty of Engineering @ Cairo University 3 Introduction LTE vs. HSPA Evolution  Among different 3G releases, LTE is release 8. 3
  4. 4. All rights reserved © 2008, Faculty of Engineering @ Cairo University 4 Introduction LTE Design Targets  Capabilities.  System performance.  Deployment-related aspects.  Architecture and migration.  Radio resource management.  Complexity. 4
  5. 5. All rights reserved © 2008, Faculty of Engineering @ Cairo University 5 LTE Design Targets Capabilities  Downlink and uplink peak data rates are 100 and 50 Mbit/s respectively for 20MHz bandwidth.  In other words downlink and uplink peak rates can be expressed as 5bit/s/Hz and 2.5 bit/s/Hz.  Supports both TDD and FDD.  Control plane latency:  From an idle mode state : 100ms  From a Cell_PCH state : 50ms  User plane latency: 5ms 5
  6. 6. All rights reserved © 2008, Faculty of Engineering @ Cairo University 6 LTE Design Targets Capabilities  At least 200 mobile terminals in the active state for 5MHz bandwidth.  If bandwidth is more than 5MHz, at least 400 terminals should be supported.  Number of inactive terminals should be higher. 6
  7. 7. All rights reserved © 2008, Faculty of Engineering @ Cairo University 7 Introduction LTE Design Targets  Capabilities.  System performance.  Deployment-related aspects.  Architecture and migration.  Radio resource management.  Complexity. 7
  8. 8. All rights reserved © 2008, Faculty of Engineering @ Cairo University 8 LTE Design Targets System Performance  System performance design targets include:  User throughput.  Spectrum efficiency.  Mobility.  Coverage.  Enhanced MBMS. 8
  9. 9. All rights reserved © 2008, Faculty of Engineering @ Cairo University 9 LTE Design Targets User Throughput 9
  10. 10. All rights reserved © 2008, Faculty of Engineering @ Cairo University 10 LTE Design Targets Mobility  Maximum performance is achieved at speeds 0-15 km/Hr  Up to 120 km/Hr, LTE should provide high performance.  Above 120 km/Hr, connection should be maintained.  Maximum speed is 350 km/Hr (may reach 500 km/Hr for wider bandwidths). 10
  11. 11. All rights reserved © 2008, Faculty of Engineering @ Cairo University 11 LTE Design Targets Coverage  It is the maximum distance between the cell site and a mobile terminal in the cell.  It is also called cell radius.  Cell radius is around 5km.  For radius > 30km, user throughput is degraded.  Cells with radius > 100km should not precluded. 11
  12. 12. All rights reserved © 2008, Faculty of Engineering @ Cairo University 12 LTE Design Targets Enhanced MBMS  MBMS is defined to be Multimedia Broadcast/Multicast Service.  The requirement for the broadcast case is a spectral efficiency of 1 bits/s/Hz.  This corresponds to around 16 mobile-TV channels using in the order of 300 kbits/s each, in 5 MHz spectrum allocation. 12
  13. 13. All rights reserved © 2008, Faculty of Engineering @ Cairo University 13 Introduction LTE Design Targets  Capabilities.  System performance.  Deployment-related aspects.  Architecture and migration.  Radio resource management.  Complexity. 13
  14. 14. All rights reserved © 2008, Faculty of Engineering @ Cairo University 14 LTE Design Targets Deployment Related Aspects  Deployment scenarios.  Coexistence and internetworking with other 3GPP RATs such as GSM and WCDMA/HSPA.  Spectrum deployment.  Spectrum flexibility. 14
  15. 15. All rights reserved © 2008, Faculty of Engineering @ Cairo University 15 LTE Design Targets Deployment Scenarios  Two possible scenarios:  LTE system is deployed as a stand alone system.  LTE system is deployed together with other radio access technologies (with WCDMA/HSPA ands/or GSM systems) 15
  16. 16. All rights reserved © 2008, Faculty of Engineering @ Cairo University 16 LTE Design Targets Interaction With Other RATs  Interruption requirements : longest acceptable interruption in the radio link when moving between the different radio access technologies, for both real-time and non-real-time services. 16
  17. 17. All rights reserved © 2008, Faculty of Engineering @ Cairo University 17 LTE Design Targets Spectrum Flexibility & Deployment  LTE spectrum is to be deployed in existing IMT- 2000 frequency bands.  This implies coexistence with the systems that are already deployed in those bands.  It should be possible to deploy LTE-based RA in both paired and unpaired spectrum allocations.  That is LTE should support both Frequency Division Duplex (FDD), and Time Division Duplex (TDD). 17
  18. 18. All rights reserved © 2008, Faculty of Engineering @ Cairo University 18 LTE Design Targets Spectrum Flexibility & Deployment  FDD systems are deployed in paired spectrum allocations.  They have one frequency range intended for downlink transmission and another for uplink transmission.  TDD systems are deployed in unpaired spectrum allocations. 18
  19. 19. All rights reserved © 2008, Faculty of Engineering @ Cairo University 19 LTE Design Targets Example  An example is the IMT-2000 spectrum at 2 GHz, that is, the IMT-2000 ‘core band’.  It consists of the paired frequency bands 1920– 1980MHz and 2110–2170MHZ intended for FDD-based radio access.  It has also the two frequency bands 1910– 1920MHz and 2010–2025MHz intended for TDD based radio access. 19
  20. 20. All rights reserved © 2008, Faculty of Engineering @ Cairo University 20 LTE Design Targets Example 20
  21. 21. All rights reserved © 2008, Faculty of Engineering @ Cairo University 21 LTE Design Targets Spectrum Flexibility & Deployment  LTE needs to be scalable in the frequency domain and operate in different bands.  This flexibility requirement is stated as a list of LTE spectrum allocations (1.25, 1.6, 2.5, 5, 10, 15 and 20 MHz).  Furthermore, LTE should be able to operate in unpaired as well as paired spectrum.  LTE should also be possible to deploy in different frequency bands. 21
  22. 22. All rights reserved © 2008, Faculty of Engineering @ Cairo University 22 Introduction LTE Design Targets  Capabilities.  System performance.  Deployment-related aspects.  Architecture and migration.  Radio resource management.  Complexity. 22
  23. 23. All rights reserved © 2008, Faculty of Engineering @ Cairo University 23 LTE Design Targets Architecture & Migration 23
  24. 24. All rights reserved © 2008, Faculty of Engineering @ Cairo University 24 AGENDA:  Introduction  LTE technologies  LTE radio interface  LTE physical layer  Frame structure  Physical layer processing  Physical layer procedures 24
  25. 25. All rights reserved © 2008, Faculty of Engineering @ Cairo University 25 LTE Technologies  Equalization against radio-channel frequency selectivity.  Uplink FDMA with flexible bandwidth assignment.  DFT Spread OFDM (DFTS-OFDM), called also (SC-FDMA).  CAZAC Sequences 25
  26. 26. All rights reserved © 2008, Faculty of Engineering @ Cairo University 26 LTE Technologies Equalization  Three main equalization techniques were proposed for LTE  Time domain linear equalization.  Frequency domain equalization.  Other equalization techniques. 26
  27. 27. All rights reserved © 2008, Faculty of Engineering @ Cairo University 27 LTE Technologies Time Domain Equalization  A filter with an impulse response is applied to the received signal. ( )w  27 ( )w 
  28. 28. All rights reserved © 2008, Faculty of Engineering @ Cairo University 28 LTE Technologies Time Domain Equalization  Matched filter  Disadvantage: Maximizes SNR, but does not compensate for any radio channel frequency selectivity.  Inverse-channel filter:  Disadvantage: Does not care about noise level although it cancels channel frequency selectivity. 28 * ( ) ( )w h  ( ) ( ) 1h w  
  29. 29. All rights reserved © 2008, Faculty of Engineering @ Cairo University 29 LTE Technologies Time Domain Equalization  Minimum Mean Square Error (MMSE) Equalizer.  Error between transmitted signal received signal should be minimized. 29 ^ 2 {[ ( ) ( )] }E s t s t  
  30. 30. All rights reserved © 2008, Faculty of Engineering @ Cairo University 30 LTE Technologies Frequency Domain Equalization  Reduces equalizer complexity.  For each processing block of size N, the frequency-domain equalization basically consists of:  A size-N DFT/FFT.  N complex multiplications (the frequency- domain filter).  A size-N inverse DFT/FFT. 30
  31. 31. All rights reserved © 2008, Faculty of Engineering @ Cairo University 31 LTE Technologies Frequency Domain Equalization 31
  32. 32. All rights reserved © 2008, Faculty of Engineering @ Cairo University 32 LTE Technologies Frequency Domain Equalization  By means of cyclic prefix, we can design our equalizer such that it reverses the effect of the channel. 32 * 2 0| | k k k H W H N  
  33. 33. All rights reserved © 2008, Faculty of Engineering @ Cairo University 33 LTE Technologies Other Techniques  Decision-Feedback Equalization (DFE)  Implies that previously detected symbols are fed back and used to cancel the contribution of the corresponding transmitted symbols to the overall signal corruption.  Maximum-Likelihood (ML) detection  Also known as Maximum Likelihood Sequence Estimation (MLSE) 33
  34. 34. All rights reserved © 2008, Faculty of Engineering @ Cairo University 34 LTE Technologies Flexible BW Assignment  Orthognality between users is maintained either by TDMA or FDMA. 34 TDMA FDMA
  35. 35. All rights reserved © 2008, Faculty of Engineering @ Cairo University 35 LTE Technologies Flexible BW Assignment  As TDMA assigns the whole band to each user, it is used more than FDMA.  The mobile terminal generally can not transmit much power.  Some times due to channel conditions, data rate is limited by power rather than bandwidth. In these cases, although the whole band is assigned to the user it can not fully utilize it. 35
  36. 36. All rights reserved © 2008, Faculty of Engineering @ Cairo University 36 LTE Technologies Flexible BW Assignment  This will lead to inefficient use of the whole bandwidth.  Proposed solution:  Assign part of the spectrum to another user.  This is some sort of mixing between TDMA and FDMA.  This will lead to a more efficient bandwidth utilization 36
  37. 37. All rights reserved © 2008, Faculty of Engineering @ Cairo University 37 LTE Technologies DFT-Spread OFDM  SC-OFDMA combines:  Small variations in the instantaneous power of the transmitted signal (‘single carrier’ property).  Possibility for low-complexity high-quality equalization in the frequency domain.  Possibility for FDMA with flexible bandwidth assignment. 37
  38. 38. All rights reserved © 2008, Faculty of Engineering @ Cairo University 38 LTE Technologies DFT-Spread OFDM  DFT/IDFT combination achieves multiplexing between users.  Padding with zeros in frequency domain reduces PAR (remember the delta function example).  Cyclic prefix simplifies the frequency domain equalization at the receiver side.  M controls LTE bandwidth. s M BW f N   38 s M BW f N  
  39. 39. All rights reserved © 2008, Faculty of Engineering @ Cairo University 39 LTE Technologies PAR Reduction 39
  40. 40. All rights reserved © 2008, Faculty of Engineering @ Cairo University 40 LTE Technologies DFTS-OFDM Demodulator 40
  41. 41. All rights reserved © 2008, Faculty of Engineering @ Cairo University 41 LTE Technologies DFTS-OFDM Demodulator  Equalization is also needed here. 41
  42. 42. All rights reserved © 2008, Faculty of Engineering @ Cairo University 42 LTE Technologies User Multiplexing 42 Equal BW assignment Non-equal BW assignment
  43. 43. All rights reserved © 2008, Faculty of Engineering @ Cairo University 43  With a raised cosine shaping instead of zero padding, PAR can be more and more reduced. 43 LTE Technologies DFTS-OFDM With Spectrum Shaping
  44. 44. All rights reserved © 2008, Faculty of Engineering @ Cairo University 44 LTE Technologies DFTS-OFDM With Spectrum Shaping  α is the roll off factor of the raised cosine.  As α increases B.W. overhead increases. 44
  45. 45. All rights reserved © 2008, Faculty of Engineering @ Cairo University 45  Constant or almost constant amplitude in line with the basic characteristics of the LTE uplink transmission scheme (low-PAR ‘single-carrier’).  Zero time-domain auto-correlation properties in order to allow for accurate uplink channel estimation.  One set of sequences with the CAZAC property is the set of Zadoff–Chu sequences.  In the frequency domain, a Zadoff–Chu sequence of length MZC can be expressed as: 45  u is the index of the Zadoff–Chu sequence within the set of Zadoff–Chu sequences of length MZC. LTE Technologies CAZAC Sequences
  46. 46. All rights reserved © 2008, Faculty of Engineering @ Cairo University 46 AGENDA:  Introduction  LTE technologies  LTE radio interface  LTE physical layer  Frame structure  Physical layer processing  Physical layer procedures  References 46
  47. 47. All rights reserved © 2008, Faculty of Engineering @ Cairo University 47 LTE Radio Interface Protocol Stack 47  Packet Data Convergence Protocol (PDCP)  performs IP header compression based on ROHC, a standardized header-compression algorithm used in WCDMA as well as several other mobile-communication standards.  Responsible for ciphering and integrity protection of the transmitted data Downlink LTE protocol stack 47
  48. 48. All rights reserved © 2008, Faculty of Engineering @ Cairo University 48 LTE Radio Interface Protocol Stack 48  Radio Link Control (RLC)  Responsible for segmentation/concaten at- ion, retransmission handling, and in- sequence delivery to higher layers.  RLC offers services to the PDCP in the form of radio bearers. Downlink LTE protocol stack 48
  49. 49. All rights reserved © 2008, Faculty of Engineering @ Cairo University 49 LTE Radio Interface Protocol Stack 49  Medium Access Control (MAC)  handles hybrid-ARQ retransmissions  Responsible for uplink and downlink scheduling.  MAC offers services to the RLC in the form of logical channels.  The scheduling functionality is located in the eNodeB, which has one MAC entity per cell, for both uplink and downlink. Downlink LTE protocol stack 49
  50. 50. All rights reserved © 2008, Faculty of Engineering @ Cairo University 50 LTE Radio Interface Protocol Stack 50  Medium Access Control (MAC)  DL/UL scheduling.  Dynamically determine, in each 1 ms interval, which terminal (s) that are supposed to receive DL-SCH transmission (transmit UL-SCH) and on what resources.  The scheduler is also responsible for selecting the transport-block size, the modulation scheme, and the antenna mapping (in case of multi-antenna transmission).  Downlink channel conditions can be measured by all mobile terminals in the cell by observing the reference signals transmitted by the eNodeB.  All mobile terminals can share the same reference signal for channel-quality-estimation purposes.  Information about the downlink channel conditions, necessary for channel dependent scheduling, is fed back from the mobile terminal to the eNodeB via channel-quality reports (channel quality indicators). 50
  51. 51. All rights reserved © 2008, Faculty of Engineering @ Cairo University 51 LTE Radio Interface Protocol Stack 51  Medium Access Control (MAC)  DL/UL scheduling.  Estimating the uplink channel quality is not as straightforward as is the case for the downlink.  Estimating the uplink channel quality require a sounding reference signal transmitted from each mobile terminal for which the eNodeB wants to estimate the uplink channel quality. 51
  52. 52. All rights reserved © 2008, Faculty of Engineering @ Cairo University 52 LTE Radio Interface Protocol Stack 52  Physical Layer (PHY)  Handles coding/decoding, modulation/demodulatio n, multi-antenna mapping,  The physical layer offers services to the MAC layer in the form of transport channels. Downlink LTE protocol stack 52
  53. 53. All rights reserved © 2008, Faculty of Engineering @ Cairo University 53  LTE_DETACHED  Used @ power up when the mobile terminal is not known to the network.  Before any further communication, the mobile terminal need to register with the network using the random- access procedure.  LTE_ACTIVE  Mobile terminal is active with transmitting and receiving data. LTE Radio Interface LTE States 5353
  54. 54. All rights reserved © 2008, Faculty of Engineering @ Cairo University 54  LTE_ACTIVE  Mobile terminal is active with transmitting and receiving data.  IN_SYNC  Uplink is synchronized with eNodeB  OUT_SYNC  Uplink is not synchronized with eNodeB.  Mobile terminal needs to perform a random-access procedure to restore uplink synchronization. LTE Radio Interface LTE States 5454
  55. 55. All rights reserved © 2008, Faculty of Engineering @ Cairo University 55  LTE_IDLE  Low activity state to reduce battery consumption.  The only uplink transmission activity that may take place is random access to move to LTE_ACTIVE.  In the downlink, the mobile terminal can periodically wake up in order to be paged for incoming calls  The network knows at least the group of cells in which paging of the mobile terminal is to be done. LTE Radio Interface LTE States 5555
  56. 56. All rights reserved © 2008, Faculty of Engineering @ Cairo University 56 AGENDA:  Introduction  LTE technologies  LTE radio interface  LTE physical layer  Physical layer channels, services and Frame structure  Physical layer processing  Physical layer procedures 56
  57. 57. All rights reserved © 2008, Faculty of Engineering @ Cairo University 57 LTE Physical Layer Supported Channels  Downlink Physical Channels:  Physical Downlink Shared Channel (PDSCH),  Physical Multicast Channel (PMCH),  Physical Downlink Control Channel (PDCCH),  Physical Broadcast Channel (PBCH),  Physical Control Format Indicator Channel (PCFICH)  Physical Hybrid ARQ Indicator Channel (PHICH).  Uplink Physical Channels :  Physical Random Access Channel (PRACH),  Physical Uplink Shared Channel (PUSCH),  Physical Uplink Control Channel (PUCCH). 5757
  58. 58. All rights reserved © 2008, Faculty of Engineering @ Cairo University 58 LTE Physical Layer Service provided to upper layers  Error detection on transport channel and indication to higher layers.  FEC encoding/decoding of the transport channel.  Hybrid ARQ soft-combining.  Rate matching of coded transport channel to physical channels.  Mapping of the coded transport channel onto physical channels.  Power weighting of physical channels.  Modulation and demodulation of physical channels.  Frequency and time synchronization.  Radio characteristics measurements and indication to higher layers.  Multiple Input Multiple Output (MIMO) antenna processing.  Transmit Diversity (TX diversity).  5858
  59. 59. All rights reserved © 2008, Faculty of Engineering @ Cairo University 59 LTE Physical Layer Overall Time Domain Structure  Tframe =10 ms  Consisting of ten equally sized subframes of length Tsubframe =1 ms.  Specification can be expressed as multiples of a basic time unit Ts =1/30720000.  Tframe =307200 ・ Ts and Tsubframe =30720 ・ Ts. 59
  60. 60. All rights reserved © 2008, Faculty of Engineering @ Cairo University 60 LTE Physical Layer Overall Time Domain Structure  different subframes of a frame can either be used for downlink or uplink transmission.  in case of FDD all subframes of a carrier are either used for downlink transmission or uplink transmission. 60
  61. 61. All rights reserved © 2008, Faculty of Engineering @ Cairo University 61 LTE Physical Layer Overall Time Domain Structure  In case of TDD subframe 0 and 5 are always assigned for downlink transmission while the remaining can be flexibly assigned to be used for either downlink or uplink transmission.  These subframes include the LTE synchronization signals.  The synchronization signals are transmitted on the downlink of each cell and are intended to be used for initial cell search as well as for neighbor-cell search. 61
  62. 62. All rights reserved © 2008, Faculty of Engineering @ Cairo University 62 LTE Physical Layer Overall Time Domain Structure  Type 1 LTE frame structure applicable for both FDD and TDD.  For LTE operating with TDD there is also an alternative or Type 2 frame structure , designed for coexistence with systems based on the current 3GPP TD-SCDMA-based standard. 62
  63. 63. All rights reserved © 2008, Faculty of Engineering @ Cairo University 63 LTE Physical Layer Downlink Transmission scheme  The downlink physical resource:  1 ms sub-frame consists of two equally sized slots of length Tslot =0.5 ms.  symbol time Tu =1/∆f ≈ 66.7μs (2048 ・ Ts).  Two cyclic-prefix lengths for LTE:  Normal CP  Extended CP (MBSFN) 63
  64. 64. All rights reserved © 2008, Faculty of Engineering @ Cairo University 64 LTE Physical Layer Downlink Transmission scheme  The downlink physical resource 64
  65. 65. All rights reserved © 2008, Faculty of Engineering @ Cairo University 65 LTE Physical Layer Downlink Transmission scheme  The downlink physical resource  Resource element corresponds to one OFDM subcarrier during one OFDM symbol interval.  OFDM subcarrier spacing ∆f=15 kHz.  Sampling rate fs =15000 ・ NFFT (NFFT =2048)  Ts defined is the sampling time of FFT-based transmitter/receiver. 65
  66. 66. All rights reserved © 2008, Faculty of Engineering @ Cairo University 66 LTE Physical Layer Downlink Transmission scheme  The downlink physical resource  Subcarriers are grouped into resource blocks.  Resource block consists of 12 consecutive subcarriers.  An unused DC-subcarrier in the center of the downlink spectrum. As it may coincide with the local-oscillator frequency at the base-station transmitter and/or mobile-terminal receiver.  Nsc =12 ・ NRB +1  6<NRB<110   1MHz<DL B.W.<20MHz 66
  67. 67. All rights reserved © 2008, Faculty of Engineering @ Cairo University 67 LTE Physical Layer Downlink Transmission scheme  The downlink physical resource 67
  68. 68. All rights reserved © 2008, Faculty of Engineering @ Cairo University 68 LTE Physical Layer Downlink Transmission scheme  Downlink reference signals  DL reference symbols are the first and the third last OFDM symbols of each slot and with a frequency-domain spacing of six subcarriers.  A frequency-domain spacing of three subcarriers between the first and second reference symbols. 68
  69. 69. All rights reserved © 2008, Faculty of Engineering @ Cairo University 69 LTE Physical Layer Downlink Transmission scheme  Reference-signals sequences and physical- layer cell identity:  510 reference signal sequences, corresponding to 510 different cell identities.  Reference-signal sequence is the product of a two-dimensional pseudo-random sequence and a two-dimensional orthogonal sequence.  170 pseudo-random sequences corresponding to one out of 170 cell-identity groups.  3 orthogonal sequences corresponding to a specific cell identity within each cell-identity group. 69
  70. 70. All rights reserved © 2008, Faculty of Engineering @ Cairo University 70 LTE Physical Layer Downlink Transmission scheme  Reference-signal frequency hopping:  Frequency-domain positions of the reference symbols may also vary between consecutive subframes.  First reference symbols: p(k) = (p0 + 6 ・ i + offset(k)) mod 6  Second reference symbols: p(k) = (p0 + 6 ・ i + 3 + offset(k)) mod 6  Frequency-hopping pattern has a period of length 10  170 different frequency-hopping patterns defined, where each pattern corresponds to one cell-identity group. 70
  71. 71. All rights reserved © 2008, Faculty of Engineering @ Cairo University 71 LTE Physical Layer Downlink Transmission scheme  Reference signals for MCBSFN: 71
  72. 72. All rights reserved © 2008, Faculty of Engineering @ Cairo University 72 LTE Physical Layer Downlink Transmission scheme  Reference signals for multi-antenna transmission: 72
  73. 73. All rights reserved © 2008, Faculty of Engineering @ Cairo University 73 LTE Physical Layer Uplink Transmission scheme  The uplink physical resource:  ∆f =15 kHz  In contrast to the downlink, no unused DC- subcarrier is defined for the uplink. 73
  74. 74. All rights reserved © 2008, Faculty of Engineering @ Cairo University 74 LTE Physical Layer Uplink Transmission scheme  The uplink physical resource:(cont.)  The presence of a DC-carrier in the center of the spectrum would have made it impossible to allocate the entire system bandwidth to a single mobile terminal and still keep the low-PAR single- carrier property of the uplink transmission.  The DFT-based pre-coding, the impact of any DC interference will be spread over the block of M modulation symbols and will therefore be less harmful compared to normal OFDM transmission. 74
  75. 75. All rights reserved © 2008, Faculty of Engineering @ Cairo University 75 LTE Physical Layer Uplink Transmission scheme  The uplink physical resource 75
  76. 76. All rights reserved © 2008, Faculty of Engineering @ Cairo University 76 LTE Physical Layer Uplink Transmission scheme  The uplink physical resource:(cont.)  Overall time–frequency resource assigned to a mobile terminal must always consist of consecutive subcarriers. 76
  77. 77. All rights reserved © 2008, Faculty of Engineering @ Cairo University 77 LTE Physical Layer Uplink Transmission scheme  The uplink physical resource:(cont.)  Inter-slot frequency hopping implies that the physical resources used for uplink transmission in the two slots of a subframe do not occupy the same set of subcarriers.  Frequency hopping provides additional frequency diversity, assuming that the hops are in the same order as or larger than the channel coherence bandwidths.  provides interference diversity (interference averaging),assuming that the hopping patterns are different in neighbor cells. 77
  78. 78. All rights reserved © 2008, Faculty of Engineering @ Cairo University 78 LTE Physical Layer Uplink Transmission scheme  Uplink reference signals:  Reference signals frequency multiplexed with data from the same mobile terminal is not possible.  Importance of low power variations for uplink transmissions.  Reference signals are time multiplexed with uplink data. 78
  79. 79. All rights reserved © 2008, Faculty of Engineering @ Cairo University 79 LTE Physical Layer Uplink Transmission scheme  Reference signals for channel sounding:  UL channel-dependent scheduling by assigning uplink resources to a mobile terminal depending on the instantaneous channel quality.  Estimates of the frequency-domain channel quality is needed.  DL by Reporting the estimated channel quality to the network by means of a Channel Quality Indicator (CQI).  Wide band reference signals 79
  80. 80. All rights reserved © 2008, Faculty of Engineering @ Cairo University 80 LTE Physical Layer Uplink Transmission scheme  Reference signals for channel sounding:(cont.) 80
  81. 81. All rights reserved © 2008, Faculty of Engineering @ Cairo University 81 AGENDA:  Introduction  LTE technologies  LTE radio interface  LTE physical layer  Frame structure  Physical layer processing  Physical layer procedures 81
  82. 82. All rights reserved © 2008, Faculty of Engineering @ Cairo University 82  Physical-layer blocks which are dynamically controlled by the MAC layer are shown in grey.  Semi-statically configured physical-layer blocks are shown in white. 8282 LTE Physical Layer Downlink Channel Processing
  83. 83. All rights reserved © 2008, Faculty of Engineering @ Cairo University 83  Physical-layer blocks which are dynamically controlled by the MAC layer are shown in grey.  while semi-statically configured physical-layer blocks are shown in white. 83 LTE Physical Layer Uplink Channel Processing
  84. 84. 84 84 LTE Physical Layer Transport Channel Processing  Multiplexing and channel coding  Different channels may undertake different combination of these block as we will see later on. 84 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  85. 85. 8585 LTE Physical Layer Transport Channel Processing  CRC attachment  Cyclic Redundancy Check (CRC) is calculated and appended to each transport block. The CRC allows for receiver-side detection of residual errors in the decoded transport block.  CRC parity bits are generated by one of the following cyclic generator polynomials:  The bits after CRC attachment are denoted by where B = A+ L. The relation between ak and bk is: 85 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  86. 86.  CRC attachment  DL-SCH and MCH CRC parity length is L = 24  BCH CRC parity length is L = 16  DL-CCH CRC parity length is L = 16  16 however parity bit attachment differs from that defined before and shall be performed as CRC calculation gives a sequence of bits  The relation between ak and ck is where K = A+ L and is the UE Identity sequence 8686 LTE Physical Layer Transport Channel Processing 86 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  87. 87.  CRC attachment  UL-SCH: The parity bits are computed and attached to the UL-SCH transport block by setting L to 24 bits.  UL-CSH: N/A  UL-RCH:N/A 8787 LTE Physical Layer Transport Channel Processing 87 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  88. 88.  Code Block Segmentation  The input bit sequence to the code block segmentation is denoted by, where B > 0. If B is larger than the maximum code block size Z, segmentation of the input bit sequence is performed and an additional CRC sequence of L = 24 bits is attached to each code block. The maximum code block size is Z = 6144.  Total number of code blocks C is determined by: If B<=Z L = 0 C = 1 B’ = B Else L = 24 C = ceil ( B/(Z-L) ) B’ = B + C*L End This block is used only in M-CH & UL/DL-SCH. 8888 LTE Physical Layer Transport Channel Processing 88 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  89. 89.  Channel Coding  There are two convolution coding types used with LTE  Tail biting convolution coding  Turbo coding  The bit sequence input for a given code block to channel coding is denoted by  where K is the number of bits to encode. After encoding the bits are denoted by  where D is the number of encoded bits per output stream and i indexes the encoder output stream. The relation between and between K and D is dependent on the channel coding scheme. 8989 LTE Physical Layer Transport Channel Processing 89 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  90. 90.  Channel Coding  Tail biting convolutional coding  A tail biting convolutional code with constraint length 7 and coding rate 1/3 is defined. 9090 LTE Physical Layer Transport Channel Processing 90 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  91. 91.  Channel Coding  Turbo coding  The scheme of turbo encoder is a Parallel Concatenated Convolutional Code (PCCC) with two 8-state constituent encoders and one turbo code internal interleaver. The coding rate of turbo encoder is 1/3. 9191 LTE Physical Layer Transport Channel Processing 91 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  92. 92.  Channel Coding  DL-SCH and MCH LTE uses turbo code rate 1/3  BCH LTE uses tail biting convolutional code rate 1/3  DL-CCH LTE uses tail biting convolutional code rate 1/3  CFI LTE defines block code as shown below. 9292 LTE Physical Layer Transport Channel Processing 92 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  93. 93.  Channel Coding  UL-SCH: Turbo coding with rate 1/3  UL-CCH: not specified yet according to release 8, Sep07  Three forms of channel coding are proposed, one for the channel quality information (CQI), another for HARQ-ACK (acknowledgement) and another for channel quality information (CQI) and HARQ-ACK.  UL-RCH: N/A 9393 LTE Physical Layer Transport Channel Processing 93 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  94. 94.  Rate matching  Rate matching for DL-SCH and UL-SCH is defined per coded block and consists of interleaving the three information bit streams, followed by the collection of bits and the generation of a circular buffer. 9494 LTE Physical Layer Transport Channel Processing 94 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  95. 95.  Rate matching  Sub-block interleaver  The bits input to the block interleaver are denoted by where D is the number of bits.  The output bit sequence from the block interleaver is derived as follows:  Construct R x C matrix such that C=32 and D <= R * C.  If R × C > D, then ND = (R × C – D) dummy bits are padded.  Write the input bit sequence into the R × C matrix row by row starting with bit y0 in column 0 of row 0. 9595 LTE Physical Layer Transport Channel Processing 95 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  96. 96.  Rate matching  Sub-block interleaver  The bits input to the block interleaver are denoted by where D is the number of bits.  The output bit sequence from the block interleaver is derived as follows:  Construct R x C matrix such that C=32 and D <= R * C.  If R × C > D, then ND = (R × C – D) dummy bits are padded.  Write the input bit sequence into the R × C matrix row by row starting with bit y0 in column 0 of row 0. 9696 LTE Physical Layer Transport Channel Processing 96 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  97. 97.  Rate matching  Sub-block interleaver  For Perform the inter-column permutation for the matrix based on the pattern that in the below table, where P(j) is the original column position of the j-th permuted column. After permutation of the columns, the inter-column permuted R × C matrix is equal to  9797 LTE Physical Layer Transport Channel Processing 97 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  98. 98.  Rate matching  The output of the block interleaver is the bit sequence read out column by column from the inter-column permuted R × C matrix.  The output of the sub-block interleaver is denoted by Where P, the permutation function, is defined in the previous Table . 9898 LTE Physical Layer Transport Channel Processing 98 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  99. 99.  Rate matching  Bit collection, selection and transmission 9999 LTE Physical Layer Transport Channel Processing 99 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  100. 100.  Code Block concatenation.  Simply this block concatenate the different code blocks (C code block) that are segmented before in the code block segmentation the output of this block is fed to the scrambling and modulation blocks as described in the following section. 100100 LTE Physical Layer Transport Channel Processing 100 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  101. 101.  Downlink modulation and antenna coding 101101 LTE Physical Layer Transport Channel Processing 101 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  102. 102.  Downlink modulation and antenna coding  Scrambling  Block of bits delivered by the code block concatenation is multiplied (XOR operation) by a bit-level scrambling sequence  By applying different scrambling sequences for neighbor cells, the interfering signal(s) after de-scrambling are randomized, ensuring full utilization of the processing gain provided by the channel code.  In case of MBSFN-based transmission using the MCH transport channel, the same scrambling should be applied to all cells taking part in a certain MBSFN transmission (cell-common scrambling) 102102 LTE Physical Layer Transport Channel Processing 102 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  103. 103.  Downlink modulation  The downlink data modulation transforms a block of scrambled bits to corresponding block of complex modulation symbols.  modulation schemes supported for the LTE are QPSK, 16QAM, and 64QAM, corresponding to two, four, and six bits per modulation symbol.  All these modulation schemes are applicable in case of DL-SCH transmission. For other transport channels certain restrictions may apply. As an example, only QPSK modulation can be applied in case of BCH transmission, and DL-CCH 103103 LTE Physical Layer Transport Channel Processing 103 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  104. 104.  Antenna mapping  Layer mapping and pre-coding  Antenna Mapping jointly processes the modulation symbols corresponding to transport blocks, and maps the result to the different antennas.  LTE supports up to four transmit antennas  Antenna mapping can be configured in different ways to provide different multi-antenna schemes including transmit diversity, and spatial multiplexing 104104 LTE Physical Layer Transport Channel Processing 104 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  105. 105.  Antenna mapping  Layer mapping and pre-coding  The layer mapping provides de-multiplexing of the modulation symbols of each codeword (coded and modulated transport block) into one or multiple layers.  The pre-coding extracts exactly one modulation symbol from each layer, jointly processes these symbols, and maps the result in the frequency and antenna domain. 105105 LTE Physical Layer Transport Channel Processing 105 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  106. 106.  Antenna mapping  Example: spatial multiplexing  In case of spatial multiplexing there is, in the general case, two code words, NL layers, and NA antennas, with NL ≥ 2 and NA ≥ NL.  The following Figure illustrates the case of three layers (NL =3) and four transmit antennas (NA =4).  Layer mapping de-multiplexes the modulation symbols of the two code- words.  the first codeword is mapped to the first layer while the second codeword is mapped to the second and third layer. Thus, the number of modulation symbols of the second codeword should be twice that of the first codeword to ensure the same number of symbols on each layer.  Pre-coding then applies the pre-coding matrix W of size NA ×NL to the each layer vector vi. 106106 LTE Physical Layer Transport Channel Processing 106 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  107. 107.  Antenna mapping  Example: spatial multiplexing 107107 LTE Physical Layer Transport Channel Processing 107 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  108. 108.  Resource mapping  Maps the symbols to be transmitted on each antenna to the resource elements of the set of resource blocks assigned for the transmission of the transport block(s).  the selection of resource block can, be based on estimates of the channel quality of the different resource blocks as seen by the target mobile terminal.  downlink scheduling is carried out on a sub-frame (1 ms) basis. Thus, as a downlink resource block is defined as a number of sub-carriers during one 0.5 ms slot, the downlink resource-block assignment is always carried out in terms of pairs of resource blocks.  some of the resource elements within a resource block will not be available for transport channel mapping as they are already occupied by:  Downlink reference symbols including.  Downlink L1/L2 control signaling. 108108 LTE Physical Layer Transport Channel Processing 108 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  109. 109.  Resource mapping 109109 LTE Physical Layer Transport Channel Processing 109 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  110. 110.  Resource mapping  Downlink L1/L2 control signaling  L1/L2 control channels are mapped to the first (up to three) OFDM symbols within each subframe.  Physical resource to which the L1/L2 control signaling is mapped consists of a number of control-channel elements, where each control channel element consists of a predefined number of resource elements.  Modulated symbols of each L1/L2 control channel is then mapped to one or several control-channel elements depending on the size. 110110 LTE Physical Layer Transport Channel Processing 110 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  111. 111.  Uplink modulation and antenna coding  Scrambling  UL-SCH & UL-CCH use UE specific scrambling sequences prior to modulation.  UL-RCH: N/A 111111 LTE Physical Layer Transport Channel Processing 111 All rights reserved © 2008, Faculty of Engineering @ Cairo University
  112. 112. All rights reserved © 2008, Faculty of Engineering @ Cairo University 112  Modulation  UL-SCH supports all modulation schemes  UL-CCH uses only BPSK or QPSK according to the following table. 112112 LTE Physical Layer Transport Channel Processing
  113. 113. All rights reserved © 2008, Faculty of Engineering @ Cairo University 113  Transform pre-coding ( UL-SCH only)  Each block of complex-valued modulated symbols is divided into M symb / M sc PUSCH , each corresponding to one SC-FDMA symbol.  Transform pre-coding shall be applied according to: 113 α2,α3,α5 is a set of non-negative integers 113 LTE Physical Layer Transport Channel Processing
  114. 114. All rights reserved © 2008, Faculty of Engineering @ Cairo University 114  Mapping to physical resources  UL-SCH  The mapping to resource elements (k, l), not used for transmission of reference signals, shall be in increasing order of first the index l, then the slot number and finally the index k which is given by. 114 f hop(.) denotes the frequency-hopping pattern. k0is given by the scheduling decision. 114 LTE Physical Layer Transport Channel Processing
  115. 115. All rights reserved © 2008, Faculty of Engineering @ Cairo University 115  Mapping to physical resources  UL-CCH  The mapping to resource elements (k, l) not used for transmission of reference signals shall start with the first slot in the sub-frame. The set of values for index k shall be different in the first and second slot of the sub-frame, resulting in frequency hopping at the slot boundary. 115115 LTE Physical Layer Transport Channel Processing
  116. 116. All rights reserved © 2008, Faculty of Engineering @ Cairo University 116 AGENDA:  Introduction  LTE technologies  LTE radio interface  LTE physical layer  Frame structure  Physical layer processing  Physical layer procedures  Cell search  Random access  Paging  Power control 116
  117. 117. All rights reserved © 2008, Faculty of Engineering @ Cairo University 117 Physical Layer Procedures Cell search  Cell search is the procedure by which a UE acquires time and frequency synchronization with a cell and detects the physical layer cell ID of that cell.  LTE supports 510 different cell identities, divided into 170 cell-identity groups, each group containing three unique identities.  A cell is uniquely defined by a number in the range of 0 to 169, representing the cell-identity group, and a number in the range of 0 to 2, representing the cell identity within the cell-identity group.
  118. 118. All rights reserved © 2008, Faculty of Engineering @ Cairo University 118 Physical Layer Procedures Cell search  LTE provides a primary synchronization signal and a secondary synchronization signal on the downlink to assist in the cell search procedure .  Synchronization signals are specific sequences, inserted into the last two OFDM symbols in the first slot of sub- frame zero and five (slots number 0 and 10).
  119. 119. All rights reserved © 2008, Faculty of Engineering @ Cairo University 119  Primary and secondary synchronization signals: Physical Layer Procedures Cell search
  120. 120. All rights reserved © 2008, Faculty of Engineering @ Cairo University 120  Time/frequency structure of synchronization signals  At the beginning of the cell-search procedure, the cell bandwidth is not necessarily known.  To maintain the same cell-search procedure, regardless of the overall cell transmission bandwidth, the synchronization signals are transmitted using the 72 center subcarriers, corresponding to a bandwidth of 1.08 MHz.  Thirty-six subcarriers on each side of the DC subcarrier in the frequency domain are reserved for the synchronization signal. Physical Layer Procedures Cell search
  121. 121. All rights reserved © 2008, Faculty of Engineering @ Cairo University 121  Secondary synchronization signal generation:  The sequence used for the second synchronization signal is an interleaved concatenation of two length-31 binary sequences obtained as cyclic shifts of a single length-31 sequence generated by .  The concatenated sequence is scrambled with a scrambling sequence given by the primary synchronization signal.  The combination of two length-31 sequences defining the secondary synchronization signal differs between slot 0 and slot 10. Physical Layer Procedures Cell search )61(),...,0( dd
  122. 122. All rights reserved © 2008, Faculty of Engineering @ Cairo University 122  First step  The mobile terminal uses the primary synchronization signal to find frame timing with 5 ms ambiguity.  One possible implementation is to do matched filtering between the received signal and the sequences specified for the primary synchronization signal and get the maximum of the MF output.  Products of first step  Frame timing on a 5 ms basis.  Finding the identity within the cell-identity group.  As there is a one-to-one mapping between each of the identities in a cell-identity group and each of the three orthogonal sequences used when creating the reference signal, the terminal obtains partial knowledge about the reference signal structure in this step. Physical Layer Procedures Cell search
  123. 123. All rights reserved © 2008, Faculty of Engineering @ Cairo University 123  Second step:  Observe pairs of slots where the secondary synchronization signal is transmitted.  If (s1, s2) is an allowable pair of sequences, where s1 and s2 represent the secondary synchronization signal in subframe zero and five, respectively, the reverse pair (s2, s1) is not a valid sequence pair. Physical Layer Procedures Cell search
  124. 124. All rights reserved © 2008, Faculty of Engineering @ Cairo University 124  Products of second step:  The terminal can resolve the 5 ms timing ambiguity resulting from the first step and determine the frame timing.  As each combination (s1, s2) represents one of the cell identity groups, the cell identity group is obtained from the second cell-search step.  From the cell identity group, the terminal knows which pseudo-random sequence is used for generating the reference signal in the cell.  Once the cell-search procedure is complete, the terminal receive the broadcasted system information to obtain the remaining parameters, for example, the transmission bandwidth used in the cell. Physical Layer Procedures Cell search
  125. 125. All rights reserved © 2008, Faculty of Engineering @ Cairo University 125  After the first step, the primary synchronization signal is known and can be used for channel estimation.  The primary and secondary synchronization signals are transmitted in two subsequent OFDM symbols.  This channel estimate can be used for coherent processing of the received signal prior to the second step in order to improve performance.  Synchronization signals are located at the end of the first slot in the sub-frame, instead of the second slot to have fewer restrictions on the creation of guard times between uplink and downlink in case of TDD. Physical Layer Procedures Cell search
  126. 126. All rights reserved © 2008, Faculty of Engineering @ Cairo University 126  Initial cell search  For initial cell search, the terminal does not know the carrier frequency of the cells it is searching for.  The terminal needs to search for a suitable carrier frequency, by repeating the above procedure for any possible carrier frequency.  Initial cell search has relaxed search-time requirements.  The terminal can use any additional information it has (for example, starts searching on the same carrier frequency it was last connected to). Physical Layer Procedures Cell search
  127. 127. All rights reserved © 2008, Faculty of Engineering @ Cairo University 127  Neighbor-cell search  Neighbor-cell search has stricter timing requirements.  In the case of intra-frequency handover, the terminal does not need to search for the carrier frequency in the neighboring cell.  Not major problem as the neighboring candidate cells transmit at the same frequency as the terminal already is receiving data upon.  Data reception and neighbor-cell search are simple separate baseband functions, operating on the same received signal. Physical Layer Procedures Cell search
  128. 128. All rights reserved © 2008, Faculty of Engineering @ Cairo University 128  Neighbor-cell search (contd.):  In the case of inter-frequency handover, data reception and neighbor-cell search need to be carried out at different frequencies.  Equipping the terminal with a separate RF receiver circuitry for neighbor-cell search, is a complex solution.  A possible solution is to create gaps in the data transmission, during which the terminal can retune to a different frequency.  This is done by avoiding scheduling the terminal in one or several downlink subframes. Physical Layer Procedures Cell search
  129. 129. All rights reserved © 2008, Faculty of Engineering @ Cairo University 129 AGENDA:  Introduction  LTE technologies  LTE radio interface  LTE physical layer  Frame structure  Physical layer processing  Physical layer procedures  Cell search  Random access  Paging  Power control 129
  130. 130. All rights reserved © 2008, Faculty of Engineering @ Cairo University 130  Random access is the process by which a terminal requests a connection setup.  Purposes of random access:  Establishment of uplink synchronization.  Establishment of a unique terminal identity, C-RNTI (Cell Radio Network Temporary Identifier), known to both the network and the terminal  When?  Initial access when moving from LTE_DETACHED or LTE_IDLE to LTE_ACTIVE.  After periods of uplink inactivity when uplink synchronization is lost in LTE_ACTIVE. Physical Layer Procedures Random access
  131. 131. All rights reserved © 2008, Faculty of Engineering @ Cairo University 131 Physical Layer Procedures Random access
  132. 132. All rights reserved © 2008, Faculty of Engineering @ Cairo University 132  Step 1: Random access preamble transmission  Indicates to the network the presence of a random-access attempt and obtains uplink time synchronization.  Random-access-preamble transmissions can be either orthogonal or non-orthogonal to user data.  To avoid interference between data and random-access preamble, the transmission of the random-access preamble in LTE is made orthogonal to uplink user-data transmissions.  The network broadcasts information to all terminals about which time-frequency resources random-access preamble transmission is allowed.  The network avoids scheduling any uplink transmissions in these time-frequency resources.  A sub-frame is reserved for preamble transmissions. Physical Layer Procedures Random access
  133. 133. All rights reserved © 2008, Faculty of Engineering @ Cairo University 133  Step 1: Random access preamble transmission  The random-access preamble has a bandwidth corresponding to six resource blocks (1.08 MHz).  The same random-access preamble structure can be used, regardless of the transmission bandwidth in the cell.  Prior to the transmission of the preamble, the terminal has already obtained downlink synchronization from the cell-search procedure.  The start of an uplink frame at the terminal is defined relative to the start of the downlink frame at the terminal. Physical Layer Procedures Random access
  134. 134. All rights reserved © 2008, Faculty of Engineering @ Cairo University 134  Step 1: Random access preamble transmission  Due to the propagation delay between the base station and the terminal, the uplink transmission will be delayed relative to the downlink transmission timing at the base station.  As the distance between the base station and the terminal is not known, there will be an uncertainty in the uplink timing corresponding to twice the distance between the base station and the terminal.  To account for this uncertainty and to avoid interference with subsequent subframes not used for random access, a guard time is used. Physical Layer Procedures Random access
  135. 135. All rights reserved © 2008, Faculty of Engineering @ Cairo University 135  Step 1: Random access preamble generation  The preamble is based on Zadoff–Chu (ZC) sequences and cyclic shifted ZC sequences.  From each root Zadoff–Chu sequence X(u) ZC(k) , m−1 cyclically shifted sequences are obtained by cyclic shifts of each, where MZC is the length of the root Zadoff–Chu sequence.  The amplitude of ZC sequences is constant, which ensures efficient power amplifier utilization and maintains the low PAR properties of the single-carrier uplink.  ZC sequences also have ideal cyclic auto-correlation, which is important for obtaining an accurate timing estimation at the eNodeB.  Due to the zero cross-correlation property of cyclically shifted ZC sequences, there is no intra-cell interference from multiple random-access attempts using preambles derived from the same Zadoff–Chu root sequence. Physical Layer Procedures Random access
  136. 136. All rights reserved © 2008, Faculty of Engineering @ Cairo University  Step 1: Random access preamble generation  Preamble sequences are partitioned into groups of 64 sequences each.  Each cell is allocated one such group by defining one or several root Zadoff–Chu sequences and the cyclic shifts required to generate the set of preambles.  When performing a random-access attempt, the terminal selects one sequence at random from the set of sequences allocated to the cell the terminal is trying to access.  As long as no other terminal is performing a random- access attempt using the same sequence at the same time instant, no collisions will occur and the attempt will be detected by the network. 136 Physical Layer Procedures Random access
  137. 137. All rights reserved © 2008, Faculty of Engineering @ Cairo University 137  Step 1: Random access preamble detection  Samples over a window of length 0.8 ms are collected and converted into the frequency-domain representation using an FFT.  The output of the FFT is multiplied with the complex- conjugate frequency-domain representation of the root Zadoff–Chu sequence and the results is fed through an IFFT.  By observing the IFFT outputs, it is possible to detect which of the shifts of the Zadoff–Chu root sequence has been transmitted and its delay.  A peak of the IFFT output in interval i corresponds to the i-th cyclically shifted sequence and the delay is given by the position of the peak within the interval.  In case of multiple random-access attempts using different cyclic shifted sequences generated from the same root Zadoff–Chu sequence, there will be a peak in Physical Layer Procedures Random access
  138. 138. All rights reserved © 2008, Faculty of Engineering @ Cairo University 138  Step 1: Random access preamble detection Physical Layer Procedures Random access
  139. 139. All rights reserved © 2008, Faculty of Engineering @ Cairo University 139  Step 2: Random access response  In response to the detected random access attempt, the network will transmit a message on the DL-SCH containing:  The index of the random-access preamble sequence the network detected and for which the response is valid.  The timing correction calculated by the random-access- preamble receiver.  A scheduling grant, indicating resources the terminal shall use for the transmission of the message in the third step.  A temporary identity used for further communication between the terminal and the network. Physical Layer Procedures Random access
  140. 140. All rights reserved © 2008, Faculty of Engineering @ Cairo University 140  Step 2: Random access response  In case the network detected multiple random-access attempts (from different terminals), the individual response messages for multiple mobile terminals can be combined in a single transmission on the DL-SCH and indicated on a L1/L2 control channel using an identity reserved for random-access response.  As long as the terminals that performed random access in the same resource used different preambles, no collision will occur.  When multiple terminals are using the same random access preamble at the same time , contention will occur.  Upon reception of the random-access response in the second step, the terminal will adjust its uplink transmission timing and continue to the third step. Physical Layer Procedures Random access
  141. 141. All rights reserved © 2008, Faculty of Engineering @ Cairo University 141  Step 3: Terminal identification  Before user data can be transmitted to/from the terminal, a unique identity within the cell (C-RNTI) must be assigned to the terminal.  In the third step, the terminal transmits the necessary messages to the network using the resources assigned in the random-access response in the second step.  The terminal sends its message on the UL-SCH similar to normal scheduled data.  The use of the ‘normal’ uplink transmission scheme for message transmission allows the grant size and modulation scheme to be adjusted to different radio conditions.  The exact content of this message depends on the state of the terminal, whether it is previously known to the network or not. Physical Layer Procedures Random access
  142. 142. All rights reserved © 2008, Faculty of Engineering @ Cairo University 142  Step 4: Contention resolution  The network transmits a contention-resolution message to the terminal on the DL-SCH.  This step resolves any contention due to multiple terminals trying to access the system using the same random-access resource.  Each terminal receiving the downlink message will compare the identity in the message with the identity they transmitted in the third step.  Only a terminal which observes a match between the identity received in the fourth step and the identity transmitted as part of the third step will declare the random access procedure successful.  Since uplink synchronization already has been established, hybrid ARQ is applied to the downlink signaling in this step. Physical Layer Procedures Random access
  143. 143. All rights reserved © 2008, Faculty of Engineering @ Cairo University 143 AGENDA:  Introduction  LTE technologies  LTE radio interface  LTE physical layer  Frame structure  Physical layer processing  Physical layer procedures  Cell search  Random access  Paging  Power control 143
  144. 144. All rights reserved © 2008, Faculty of Engineering @ Cairo University 144  Paging is used for network-initiated connection setup.  An efficient paging procedure should allow the terminal to sleep with no receiver processing most of the time and to wake up only at predefined time intervals to monitor paging information from the network.  In LTE, no separate paging-indicator channel is used. Physical Layer Procedures Paging
  145. 145. All rights reserved © 2008, Faculty of Engineering @ Cairo University 145  A Discontinuous cycle is defined, which allows the terminal to sleep most of the time and only briefly wake up to monitor the L1/L2 control signaling.  If the terminal detects a group identity used for paging when it wakes up, it will process the corresponding paging message transmitted in the downlink. Physical Layer Procedures Paging
  146. 146. All rights reserved © 2008, Faculty of Engineering @ Cairo University  The paging message includes the identity of the terminal(s) being paged.  The terminal that does not find its identity will discard the received information and sleep according to the DRX cycle.  The uplink timing is unknown during the DRX cycles  no ACK/NACK signaling can take place (No hybrid ARQ can be used for paging messages). 146 Physical Layer Procedures Paging
  147. 147. All rights reserved © 2008, Faculty of Engineering @ Cairo University 147 AGENDA:  Introduction  LTE technologies  LTE radio interface  LTE physical layer  Frame structure  Physical layer processing  Physical layer procedures  Cell search  Random access  Paging  Power control 147
  148. 148. All rights reserved © 2008, Faculty of Engineering @ Cairo University  Downlink power control determines the energy per resource element (EPRE).  Energy per resource element denotes the energy prior to CP insertion and also denotes the average energy taken over all constellation points for the modulation scheme applied.  Uplink power control determines the average power over a DFT-S OFDM symbol in which the physical channel is transmitted. 148 Physical Layer Procedures Power control
  149. 149. All rights reserved © 2008, Faculty of Engineering @ Cairo University  Uplink power control:  Uplink power control controls the transmit power of the different uplink physical channels.  A cell wide overload indicator (OI) is exchanged for inter-cell power control.  An indication X is exchanged to indicate PRBs that an eNodeB scheduler allocates to cell edge UEs and that will be most sensitive to inter-cell interference.  Physical uplink shared channel power control.  Physical uplink control channel power control.  Sounding Reference Symbol power control. 149 Physical Layer Procedures Power control
  150. 150. All rights reserved © 2008, Faculty of Engineering @ Cairo University  Downlink power control:  The eNodeB determines the downlink transmit energy per resource element.  A UE shall assume downlink reference symbol EPRE is constant across the downlink system bandwidth and constant across all subframes until different RS (Reference signal) boosting information is received. 150 Physical Layer Procedures Power control
  1. A particular slide catching your eye?

    Clipping is a handy way to collect important slides you want to go back to later.

×