FastForward: Fast and Constructive Full Duplex Relays Dinesh - - PowerPoint PPT Presentation

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FastForward: Fast and Constructive Full Duplex Relays Dinesh - - PowerPoint PPT Presentation

Sep 25, 2023 147 likes •1.49k views

FastForward: Fast and Constructive Full Duplex Relays Dinesh Bharadia and Sachin Katti Stanford University & Kumu Networks The Promise of Wireless 256 QAM, 3x3 MIMO Wireless link speeds 1.3 Gbps have grown by two orders of magnitude

slide-1
SLIDE 1

FastForward: Fast and Constructive Full Duplex Relays

Dinesh Bharadia and Sachin Katti Stanford University & Kumu Networks

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SLIDE 2

The Promise of Wireless …

Wireless link speeds have grown by two

  • rders of magnitude

in the last decade due to:

802.11b 802.11g 802.11n 802.11ac 11 Mbps 54 Mbps 600 Mbps 1.3 Gbps

64 QAM, 4x4 MIMO 256 QAM, 3x3 MIMO 64 QAM, SISO QPSK, SISO

20 MHz 40 MHz 80 MHz

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SLIDE 3

The Promise of Wireless …

Wireless link speeds have grown by two

  • rders of magnitude

in the last decade due to:

  • Denser

Modulation/Coding

802.11b 802.11g 802.11n 802.11ac 11 Mbps 54 Mbps 600 Mbps 1.3 Gbps

64 QAM, 4x4 MIMO 256 QAM, 3x3 MIMO 64 QAM, SISO QPSK, SISO

20 MHz 40 MHz 80 MHz

slide-4
SLIDE 4

The Promise of Wireless …

Wireless link speeds have grown by two

  • rders of magnitude

in the last decade due to:

  • Denser

Modulation/Coding

  • MIMO

802.11b 802.11g 802.11n 802.11ac 11 Mbps 54 Mbps 600 Mbps 1.3 Gbps

64 QAM, 4x4 MIMO 256 QAM, 3x3 MIMO 64 QAM, SISO QPSK, SISO

20 MHz 40 MHz 80 MHz

slide-5
SLIDE 5

The Promise of Wireless …

Wireless link speeds have grown by two

  • rders of magnitude

in the last decade due to:

  • Denser

Modulation/Coding

  • MIMO

802.11b 802.11g 802.11n 802.11ac 11 Mbps 54 Mbps 600 Mbps 1.3 Gbps

64 QAM, 4x4 MIMO 256 QAM, 3x3 MIMO 64 QAM, SISO QPSK, SISO

20 MHz 40 MHz 80 MHz

Do we see such capacity in practice?

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SLIDE 6

The Reality of Wireless …

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SLIDE 7

The Reality of Wireless …

26 m 9m

WiFi coverage in typical home

AP

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SLIDE 8

Bitrate in Mbps (PHY layer bit rate) 20 40 120 60 80 100 140

AP

The Reality of Wireless …

26 m 9m

WiFi coverage in typical home

AP

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SLIDE 9

Bitrate in Mbps (PHY layer bit rate) 20 40 120 60 80 100 140

AP

The Reality of Wireless …

WiFi coverage & capacity don’t live up to the promised speeds

26 m 9m

WiFi coverage in typical home

AP

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SLIDE 10

The Problem

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SLIDE 11

The Problem

Signals experience propagation loss

Wall Strong Signal

AP

Weak Signal

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SLIDE 12

Bitrates in Mbps (PHY LAYER bit rate) 20 40 120 60 80 100 140 AP only

The Problem

Signals experience propagation loss

Wall Strong Signal

AP

Weak Signal

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SLIDE 13

Bitrates in Mbps (PHY LAYER bit rate) 20 40 120 60 80 100 140 AP only

The Problem

Signals experience propagation loss

Wall Strong Signal

AP

Weak Signal

AP

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SLIDE 14

Bitrates in Mbps (PHY LAYER bit rate) 20 40 120 60 80 100 140 AP only

The Problem

Signals experience propagation loss

26 m 9m

Wall Strong Signal

AP

Weak Signal

AP

slide-15
SLIDE 15

AP

Bitrates in Mbps (PHY LAYER bit rate) 20 40 120 60 80 100 140 AP only RF pinhole

The Problem

Signals experience propagation loss Can’t exploit MIMO because of correlated channels from pinholes

26 m 9m

Correlated paths Wall Strong Signal

AP

Weak Signal

AP

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SLIDE 16

AP

Bitrates in Mbps (PHY LAYER bit rate) 20 40 120 60 80 100 140 AP only RF pinhole

The Problem

Signals experience propagation loss Can’t exploit MIMO because of correlated channels from pinholes

26 m 9m

Correlated paths Wall Strong Signal

AP

Weak Signal

AP

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SLIDE 17

AP

Bitrates in Mbps (PHY LAYER bit rate) 20 40 120 60 80 100 140 AP only RF pinhole

The Problem

Signals experience propagation loss Can’t exploit MIMO because of correlated channels from pinholes

26 m 9m

Correlated paths Wall Strong Signal

AP

Weak Signal

AP

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SLIDE 18

FastForward (FF)

26 m 9m AP

slide-19
SLIDE 19

FastForward (FF)

  • Full duplex relay that significantly

increases capacity and coverage

26 m 9m FF AP

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SLIDE 20

FastForward (FF)

  • Full duplex relay that significantly

increases capacity and coverage

26 m 9m FF AP

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SLIDE 21

FastForward (FF)

  • Full duplex relay that significantly

increases capacity and coverage

  • Key Idea: Construct & forward

relaying

26 m 9m FF AP

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SLIDE 22

FastForward (FF)

  • Full duplex relay that significantly

increases capacity and coverage

  • Key Idea: Construct & forward

relaying

  • Tackles propagation loss 

significantly increases SNR

26 m 9m FF AP

slide-23
SLIDE 23

FastForward (FF)

  • Full duplex relay that significantly

increases capacity and coverage

  • Key Idea: Construct & forward

relaying

  • Tackles propagation loss 

significantly increases SNR

  • Tackles RF pinholes 

increases MIMO multiplexing

26 m 9m FF AP

slide-24
SLIDE 24

FastForward (FF)

  • Full duplex relay that significantly

increases capacity and coverage

  • Key Idea: Construct & forward

relaying

  • Tackles propagation loss 

significantly increases SNR

  • Tackles RF pinholes 

increases MIMO multiplexing

  • Experimentally achieves capacity

gain of 2.3x

26 m 9m FF AP

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SLIDE 25

20 40 120 60 80 100 140 Fast Forward Off

FastForward (FF)

  • Full duplex relay that significantly

increases capacity and coverage

  • Key Idea: Construct & forward

relaying

  • Tackles propagation loss 

significantly increases SNR

  • Tackles RF pinholes 

increases MIMO multiplexing

  • Experimentally achieves capacity

gain of 2.3x

26 m 9m AP

Bitrates in Mbps (PHY LAYER bit rate)

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SLIDE 26

20 40 120 60 80 100 140 Fast Forward On

FastForward (FF)

  • Full duplex relay that significantly

increases capacity and coverage

  • Key Idea: Construct & forward

relaying

  • Tackles propagation loss 

significantly increases SNR

  • Tackles RF pinholes 

increases MIMO multiplexing

  • Experimentally achieves capacity

gain of 2.3x

26 m 9m FF AP

Bitrates in Mbps (PHY LAYER bit rate)

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SLIDE 27

How does FF work at a high level?

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SLIDE 28

How does FF work at a high level?

AP

Direct Source Destination

Client

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SLIDE 29

How does FF work at a high level?

AP FF

Direct Source Destination

Client

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SLIDE 30

How does FF work at a high level?

  • 1. Receive signal from the source
  • 2. Process it in RF and digital
  • 3. Relay it simultaneously to the destination

AP FF

Direct Source Destination

Client

slide-31
SLIDE 31

How does FF work at a high level?

  • 1. Receive signal from the source
  • 2. Process it in RF and digital
  • 3. Relay it simultaneously to the destination

Simultaneously TX and RX

AP

Direct Source Destination

Client

slide-32
SLIDE 32

How does FF work at a high level?

  • 1. Receive signal from the source
  • 2. Process it in RF and digital
  • 3. Relay it simultaneously to the destination

Simultaneously TX and RX

AP

RX

Direct Source Destination

Client

slide-33
SLIDE 33

How does FF work at a high level?

  • 1. Receive signal from the source
  • 2. Process it in RF and digital
  • 3. Relay it simultaneously to the destination

Simultaneously TX and RX

AP

RX

RF & Digital Processing

Direct Source Destination

Client

slide-34
SLIDE 34

How does FF work at a high level?

  • 1. Receive signal from the source
  • 2. Process it in RF and digital
  • 3. Relay it simultaneously to the destination

Simultaneously TX and RX TX

AP

RX

RF & Digital Processing

Direct Source Destination

Client

slide-35
SLIDE 35

How does FF work at a high level?

  • 1. Receive signal from the source
  • 2. Process it in RF and digital
  • 3. Relay it simultaneously to the destination

Simultaneously TX and RX TX

AP

RX

RF & Digital Processing

Relayed Direct Source Destination

Client

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SLIDE 36

Isn’t this easy? Just use recent work

  • n fu

full duplex

slide-37
SLIDE 37

How to relay while receiving ?

Relayed

AP

Direct Simultaneously TX and RX TX RX

RF & Digital Processing

Client

slide-38
SLIDE 38

How to relay while receiving ?

  • Relaying & receiving 

Simultaneous TX and RX on the same frequency

Relayed

AP

Direct Simultaneously TX and RX TX RX

RF & Digital Processing

Client

slide-39
SLIDE 39

How to relay while receiving ?

  • Relaying & receiving 

Simultaneous TX and RX on the same frequency

  • Use recent work on full duplex

Relayed

AP

Direct Simultaneously TX and RX TX RX

RF & Digital Processing

Client

slide-40
SLIDE 40

How to relay while receiving ?

  • Relaying & receiving 

Simultaneous TX and RX on the same frequency

  • Use recent work on full duplex

Relayed

AP

Direct Simultaneously TX and RX TX RX

RF & Digital Processing

Full duplex TX RX

RF & Digital Processing

Client

slide-41
SLIDE 41

How to relay while receiving ?

  • Relaying & receiving 

Simultaneous TX and RX on the same frequency

  • Use recent work on full duplex

Relayed

20dB SNR

AP

Direct Simultaneously TX and RX TX RX

RF & Digital Processing

Full duplex TX RX

RF & Digital Processing

Client

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SLIDE 42
  • 90 dBm Receiver Noise floor

Relay received

  • 70dBm

How to relay while receiving ?

  • Relaying & receiving 

Simultaneous TX and RX on the same frequency

  • Use recent work on full duplex

Relayed

20dB SNR

AP

Direct Simultaneously TX and RX TX RX

RF & Digital Processing

Full duplex TX RX

RF & Digital Processing

Client

slide-43
SLIDE 43
  • 90 dBm Receiver Noise floor

Relay received

  • 70dBm

How to relay while receiving ?

  • Relaying & receiving 

Simultaneous TX and RX on the same frequency

  • Use recent work on full duplex

Relayed

Relay transmitted Amplify to MAX

20 dBm

Relay Noise

0 dBm

20dB SNR

AP

Direct Simultaneously TX and RX TX RX

RF & Digital Processing

Full duplex TX RX

RF & Digital Processing

Client

slide-44
SLIDE 44
  • 90 dBm Receiver Noise floor

Relay received

  • 70dBm

How to relay while receiving ?

  • Relaying & receiving 

Simultaneous TX and RX on the same frequency

  • Use recent work on full duplex
  • Receive signal, amplify and

simultaneously relay

Relayed

Relay transmitted Amplify to MAX

20 dBm

Relay Noise

0 dBm

20dB SNR

AP

Direct Simultaneously TX and RX TX RX

RF & Digital Processing

Full duplex TX RX

RF & Digital Processing

Full duplex TX RX

Max Amplify

Client

slide-45
SLIDE 45
  • 90 dBm Receiver Noise floor

Relay received

  • 70dBm

How to relay while receiving ?

  • Relaying & receiving 

Simultaneous TX and RX on the same frequency

  • Use recent work on full duplex
  • Receive signal, amplify and

simultaneously relay

Relayed

Relay transmitted Amplify to MAX

20 dBm

Relay Noise

0 dBm

20dB SNR

AP

Direct Simultaneously TX and RX TX RX

RF & Digital Processing

Full duplex TX RX

RF & Digital Processing

Full duplex TX RX

Max Amplify

Client

Are we done? No, this design has two problems:

  • Amplifies noise
  • Creates destructive interference
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SLIDE 46

Challenge 1: Noise Amplification

slide-47
SLIDE 47

Source (AP) Transmitted

Transmit Destination Received

  • 90 dBm Noise floor

Direct

  • 80dBm

10dB SNR

Challenge 1: Noise Amplification

Direct

slide-48
SLIDE 48

20dB SNR

Source (AP) Transmitted

Transmit Destination Received

  • 90 dBm Noise floor

Direct

  • 80dBm

10dB SNR

Challenge 1: Noise Amplification

Direct

slide-49
SLIDE 49
  • 90 dBm Receiver Noise floor

Relay received

  • 70dBm

20dB SNR

Source (AP) Transmitted

Transmit Destination Received

  • 90 dBm Noise floor

Direct

  • 80dBm

10dB SNR

Challenge 1: Noise Amplification

Direct

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SLIDE 50
  • 90 dBm Receiver Noise floor

Relay received

  • 70dBm

Relay transmitted Amplify to MAX (90 dB )

20 dBm

20dB SNR

Source (AP) Transmitted

Transmit Destination Received

  • 90 dBm Noise floor

Direct

  • 80dBm

10dB SNR

Challenge 1: Noise Amplification

Relay Noise

0 dBm

Direct

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SLIDE 51
  • 90 dBm Receiver Noise floor

Relay received

  • 70dBm

Relay transmitted Amplify to MAX (90 dB )

20 dBm

20dB SNR

Source (AP) Transmitted

Transmit

30 dB SNR

Destination Received

  • 90 dBm Noise floor

Direct

  • 80dBm

10dB SNR

Challenge 1: Noise Amplification

Relay Noise

0 dBm

Direct

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SLIDE 52
  • 90 dBm Receiver Noise floor

Relay received

  • 70dBm

Relay transmitted Amplify to MAX (90 dB )

20 dBm

20dB SNR

Source (AP) Transmitted

Transmit

30 dB SNR

Destination Received

  • 90 dBm Noise floor

Direct

  • 80dBm

10dB SNR

Challenge 1: Noise Amplification

Relay Noise

0 dBm

Relay Noise

  • 60dBm
  • 80dBm

Direct

slide-53
SLIDE 53
  • 90 dBm Receiver Noise floor

Relay received

  • 70dBm

Relay transmitted Amplify to MAX (90 dB )

20 dBm

20dB SNR

Source (AP) Transmitted

Transmit

30 dB SNR

Destination Received

  • 90 dBm Noise floor

Direct

  • 80dBm

10dB SNR

Challenge 1: Noise Amplification

Relay Noise

0 dBm

Relay Noise

  • 60dBm
  • 80dBm

Direct

slide-54
SLIDE 54
  • 90 dBm Receiver Noise floor

Relay received

  • 70dBm

Relay transmitted Amplify to MAX (90 dB )

20 dBm

20dB SNR

Source (AP) Transmitted

Transmit

30 dB SNR

Destination Received

  • 90 dBm Noise floor

Direct

  • 80dBm

10dB SNR

Challenge 1: Noise Amplification

Relay Noise

0 dBm

Relay Noise

  • 60dBm
  • 80dBm

Amplified noise destroys direct signal

Direct

slide-55
SLIDE 55

Challenge 2: Destructive Interference

AP

Direct Destination Received

  • 90 dBm Noise floor

Direct

slide-56
SLIDE 56

Challenge 2: Destructive Interference

Re Im

AP

Direct Destination Received

  • 90 dBm Noise floor

Direct

slide-57
SLIDE 57

Challenge 2: Destructive Interference

Direct Re Im

AP

Direct Destination Received

  • 90 dBm Noise floor

Direct

slide-58
SLIDE 58

Challenge 2: Destructive Interference

Direct Re Im Relayed Full Duplex TX RX

Max Amplify

AP

Direct Destination Received

  • 90 dBm Noise floor

Direct

slide-59
SLIDE 59

Challenge 2: Destructive Interference

Relayed Direct Re Im Relayed Full Duplex TX RX

Max Amplify

AP

Direct Destination Received

  • 90 dBm Noise floor

Direct

slide-60
SLIDE 60

Challenge 2: Destructive Interference

Relayed Direct Re Im Relayed Full Duplex TX RX

Max Amplify

AP

Direct Destination Received

  • 90 dBm Noise floor

Direct Relayed

+

slide-61
SLIDE 61

Challenge 2: Destructive Interference

Relayed Direct Destructive Interference Re Im Total Re Im Relayed Full Duplex TX RX

Max Amplify

AP

Direct Destination Received

  • 90 dBm Noise floor

Direct Total Relayed

+

slide-62
SLIDE 62

Construct and Forward relaying to tackle these two chall llenges

slide-63
SLIDE 63

Full Duplex TX RX

Max Amplify

Construct and Forward relaying

Relayed Full Duplex TX RX

AP

Direct

slide-64
SLIDE 64

Full Duplex TX RX

Max Amplify

Construct and Forward relaying

Basic Idea: Filter the received signal such that noise isn’t amplified and signals add constructively at the destination

Relayed Full Duplex TX RX

Construct & Forward filtering

AP

Direct

slide-65
SLIDE 65

Construct and Forward filter abstraction

RX TX

Construct & Forward filtering

Full Duplex TX RX

Naïve Amplify

Full Duplex TX RX

Construct & Forward filtering

slide-66
SLIDE 66

Construct and Forward filter abstraction

RX TX

Construct & Forward filtering

Full Duplex TX RX

Naïve Amplify

Full Duplex TX RX

Construct & Forward filtering

RX TX

Constructive amplification Constructive rotation

slide-67
SLIDE 67

Construct and Forward filter abstraction

RX TX

RX . A . ejɵ = TX

Constructive amplification Constructive rotation

Construct & Forward filtering

Full Duplex TX RX

Naïve Amplify

Full Duplex TX RX

Construct & Forward filtering

RX TX

Constructive amplification Constructive rotation

Received signal at relay Relayed signal

slide-68
SLIDE 68

Construct and Forward filter abstraction

RX TX

RX . A . ejɵ = TX

Constructive amplification Constructive rotation

Construct & Forward filtering

Full Duplex TX RX

Naïve Amplify

Full Duplex TX RX

Construct & Forward filtering

RX TX

Constructive amplification Constructive rotation

How does Construct and Forward calculate A & ejɵ ?

Received signal at relay Relayed signal

slide-69
SLIDE 69

Constructive amplification A

slide-70
SLIDE 70

Source Transmitted

20 dBm Destination Received

  • 90 dBm

Noise floor

Constructive amplification A

slide-71
SLIDE 71

90 dB loss

Source Transmitted

20 dBm Destination Received

  • 90 dBm

Noise floor

Constructive amplification A

slide-72
SLIDE 72
  • 90 dBm Receiver Noise floor

Relay received

  • 70dBm

90 dB loss

Source Transmitted

20 dBm Destination Received

  • 90 dBm

Noise floor

Constructive amplification A

slide-73
SLIDE 73
  • 90 dBm Receiver Noise floor

Relay received

  • 70dBm

90 dB loss

Source Transmitted

20 dBm

80 dB loss

Destination Received

  • 90 dBm

Noise floor

Constructive amplification A

slide-74
SLIDE 74
  • 90 dBm Receiver Noise floor

Relay received

  • 70dBm

Relay Transmitted Amplify by 80 dB

10 dBm

90 dB loss

Source Transmitted

20 dBm

80 dB loss

Destination Received

  • 90 dBm

Noise floor

Constructive amplification A

Relay Noise

  • 10 dBm
slide-75
SLIDE 75
  • 90 dBm Receiver Noise floor

Relay received

  • 70dBm

Relay Transmitted Amplify by 80 dB

10 dBm

90 dB loss

Source Transmitted

20 dBm

80 dB loss

Destination Received

  • 90 dBm

Noise floor

Constructive amplification A

Relay Noise

  • 10 dBm

Relay Noise

  • 70dBm
  • 90dBm

Relayed

slide-76
SLIDE 76
  • 90 dBm Receiver Noise floor

Relay received

  • 70dBm

Relay Transmitted Amplify by 80 dB

10 dBm

90 dB loss

Source Transmitted

20 dBm

80 dB loss

Destination Received

  • 90 dBm

Noise floor

Constructive amplification A

Relay Noise

  • 10 dBm

Relay Noise

  • 70dBm
  • 90dBm

Relayed

slide-77
SLIDE 77
  • 90 dBm Receiver Noise floor

Relay received

  • 70dBm

Relay Transmitted Amplify by 80 dB

10 dBm

90 dB loss

Source Transmitted

20 dBm

80 dB loss

Destination Received

  • 90 dBm

Noise floor

Constructive amplification A

Relay Noise

  • 10 dBm

Relay Noise

  • 70dBm
  • 90dBm

Constructive amplification factor A can be at most the propagation loss from relay to destination

Relayed

slide-78
SLIDE 78

Constructive rotation ejɵ

Relayed Full Duplex TX RX

Construct & Forward Filtering

AP

Direct

slide-79
SLIDE 79

Amplify

  • nly relay

Constructive rotation ejɵ

Direct Re Im Relayed Full Duplex TX RX

Construct & Forward Filtering

AP

Direct

slide-80
SLIDE 80

Amplify

  • nly relay

Constructive rotation ejɵ

Direct Re Im Relayed Full Duplex TX RX

Construct & Forward Filtering

AP

Direct Amplify only relay total Re Im

slide-81
SLIDE 81

Amplify

  • nly relay

Constructive relay

Constructive rotation ejɵ

Direct Re Im Relayed Full Duplex TX RX

Construct & Forward Filtering

AP

Direct Direct Re Im Amplify only relay total Re Im

slide-82
SLIDE 82

Amplify

  • nly relay

Constructive relay

Constructive rotation ejɵ

Direct Re Im Constructive relay total Relayed Full Duplex TX RX

Construct & Forward Filtering

AP

Direct Direct Re Im Amplify only relay total Re Im

slide-83
SLIDE 83

Amplify

  • nly relay

Constructive relay Constructive rotation by ejɵ

Constructive rotation ejɵ

Amplify

  • nly relay

Direct Re Im Constructive relay total Relayed Full Duplex TX RX

Construct & Forward Filtering

AP

Direct Direct Re Im Amplify only relay total Re Im

ejɵ

slide-84
SLIDE 84

Amplify

  • nly relay

Constructive relay Constructive rotation by ejɵ

Constructive rotation ejɵ

Amplify

  • nly relay

Direct Re Im Constructive relay total Relayed Full Duplex TX RX

Construct & Forward Filtering

AP

Direct Direct Re Im Amplify only relay total Re Im

Constructive rotation ejɵ should be as close as possible to the phase difference between the direct and the relay path’s channels

ejɵ

slide-85
SLIDE 85

Summary: Construct and Forward filter

RX TX

RX . A . ejɵ = TX

Constructive Amplification Constructive Rotation

Construct & Forward filtering

Full Duplex TX RX

Naïve Amplify

Full Duplex TX RX

Construct & Forward filtering

RX TX

Constructive amplification Constructive rotation

Received at relay Relayed

slide-86
SLIDE 86

Summary: Construct and Forward filter

RX TX

RX . A . ejɵ = TX

Constructive Amplification Constructive Rotation

Construct & Forward filtering

Full Duplex TX RX

Naïve Amplify

Full Duplex TX RX

Construct & Forward filtering

RX TX

Constructive amplification Constructive rotation

Received at relay Relayed

Propagation loss from relay to destination

slide-87
SLIDE 87

Summary: Construct and Forward filter

RX TX

RX . A . ejɵ = TX

Constructive Amplification Constructive Rotation

Construct & Forward filtering

Full Duplex TX RX

Naïve Amplify

Full Duplex TX RX

Construct & Forward filtering

RX TX

Constructive amplification Constructive rotation

Received at relay Relayed

Align the phases of the relay path and direct path at the destination Propagation loss from relay to destination

slide-88
SLIDE 88

High latency leads to inter-symbol interference

AP

slide-89
SLIDE 89

High latency leads to inter-symbol interference

Direct

AP

slide-90
SLIDE 90

Direct

Symbol1

CP Symbol2 CP

High latency leads to inter-symbol interference

Direct

AP

slide-91
SLIDE 91

Direct

Symbol1

CP Symbol2 CP

High latency leads to inter-symbol interference

Direct Full Duplex TX RX

Naïve Amplify

Full Duplex TX RX

Construct & Forward Filtering

AP

slide-92
SLIDE 92

Direct

Symbol1

CP Symbol2 CP

High latency leads to inter-symbol interference

Direct Relayed Full Duplex TX RX

Naïve Amplify

Full Duplex TX RX

Construct & Forward Filtering

AP

slide-93
SLIDE 93

Direct

Symbol1

CP Symbol2 CP Relayed

Symbol1

CP Symbol2 CP Δt

High latency leads to inter-symbol interference

Direct Relayed Full Duplex TX RX

Naïve Amplify

Full Duplex TX RX

Construct & Forward Filtering

AP

slide-94
SLIDE 94

Symbol1 interferes with Symbol2 Direct

Symbol1

CP Symbol2 CP Relayed

Symbol1

CP Symbol2 CP Δt

High latency leads to inter-symbol interference

Direct Relayed Full Duplex TX RX

Naïve Amplify

Full Duplex TX RX

Construct & Forward Filtering

AP

slide-95
SLIDE 95

Symbol1 interferes with Symbol2 Direct

Symbol1

CP Symbol2 CP Relayed

Symbol1

CP Symbol2 CP Δt

High latency leads to inter-symbol interference

Direct Relayed

Minimize the latency of Construct & Forward filter to avoid inter symbol interference

Full Duplex TX RX

Naïve Amplify

Full Duplex TX RX

Construct & Forward Filtering

AP

slide-96
SLIDE 96

Symbol1 interferes with Symbol2 Direct

Symbol1

CP Symbol2 CP Relayed

Symbol1

CP Symbol2 CP Δt

High latency leads to inter-symbol interference

Direct Relayed

Minimize the latency of Construct & Forward filter to avoid inter symbol interference

Full Duplex TX RX

Naïve Amplify

Full Duplex TX RX

Construct & Forward Filtering

RX TX

Constructive Amplification Constructive Rotation

AP

slide-97
SLIDE 97

Symbol1 interferes with Symbol2 Direct

Symbol1

CP Symbol2 CP Relayed

Symbol1

CP Symbol2 CP Δt

High latency leads to inter-symbol interference

Direct Relayed

Minimize the latency of Construct & Forward filter to avoid inter symbol interference

Full Duplex TX RX

Naïve Amplify

Full Duplex TX RX

Construct & Forward Filtering

RX TX

Constructive Amplification Constructive Rotation

Negligible Latency

AP

slide-98
SLIDE 98

Symbol1 interferes with Symbol2 Direct

Symbol1

CP Symbol2 CP Relayed

Symbol1

CP Symbol2 CP Δt

High latency leads to inter-symbol interference

Direct Relayed

Minimize the latency of Construct & Forward filter to avoid inter symbol interference

Full Duplex TX RX

Naïve Amplify

Full Duplex TX RX

Construct & Forward Filtering

RX TX

Constructive Amplification Constructive Rotation

Negligible Latency How do we achieve this block with minimum latency?

AP

slide-99
SLIDE 99

Low latency constructive rotation filter

RX TX = RX. ejɵ

Constructive rotation (ejɵ)

slide-100
SLIDE 100

Low latency constructive rotation filter

RX TX = RX. ejɵ RX

Constructive rotation (ejɵ)

slide-101
SLIDE 101

Low latency constructive rotation filter

RX TX = RX. ejɵ RX TX RX ejɵ

Constructive rotation (ejɵ)

slide-102
SLIDE 102

Low latency constructive rotation filter

RX TX = RX. ejɵ d4 d1 d2 d3 RX TX RX ejɵ

slide-103
SLIDE 103

Low latency constructive rotation filter

RX TX = RX. ejɵ

a4 a3 a1 a2

d4 d1 d2 d3 RX TX RX ejɵ

slide-104
SLIDE 104

Low latency constructive rotation filter

RX TX = RX. ejɵ

a4 a3 a1 a2

d4 d1 d2 d3 200 psec 100 psec 300 psec 0 psec RX TX RX ejɵ 400 psec

slide-105
SLIDE 105

Low latency constructive rotation filter

RX TX = RX. ejɵ

a4 a3 a1 a2

d4 d1 d2 d3 200 psec 100 psec 300 psec 0 psec RX TX RX ejɵ RX(d1) RX(d2) RX(d4) RX(d3) 400 psec

slide-106
SLIDE 106

Low latency constructive rotation filter

RX TX = RX. ejɵ

a4 a3 a1 a2

d4 d1 d2 d3 200 psec 100 psec 300 psec 0 psec RX TX RX ejɵ RX(d1) RX(d2) RX(d4) RX(d3) 400 psec 700 psec

slide-107
SLIDE 107

Low latency constructive rotation filter

RX TX = RX. ejɵ

a4 a3 a1 a2

d4 d1 d2 d3 200 psec 100 psec 300 psec 0 psec RX RX.a1 RX.a2 RX.a3 RX.a4 TX RX ejɵ RX(d1) RX(d2) RX(d4) RX(d3) 400 psec 700 psec

slide-108
SLIDE 108

Low latency constructive rotation filter

RX TX = RX. ejɵ

a4 a3 a1 a2

d4 d1 d2 d3 200 psec 100 psec 300 psec 0 psec RX RX.a1 RX.a2 RX.a3 RX.a4 TX RX ejɵ RX(d1) RX(d2) RX(d4) RX(d3) 400 psec 700 psec

slide-109
SLIDE 109

Low latency constructive rotation filter

RX TX = RX. ejɵ

a4 a3 a1 a2

d4 d1 d2 d3 PA 200 psec 100 psec 300 psec 0 psec RX

  • RX. F

RX.a1 RX.a2 RX.a3 RX.a4 TX RX ejɵ RX(d1) RX(d2) RX(d4) RX(d3) 400 psec 700 psec

slide-110
SLIDE 110

Low latency constructive rotation filter

RX TX = RX. ejɵ

a4 a3 a1 a2

d4 d1 d2 d3 PA 200 psec 100 psec 300 psec 0 psec RX

  • RX. F

RX.a1 RX.a2 RX.a3 RX.a4 TX RX ejɵ RX(d1) RX(d2) RX(d4) RX(d3) 400 psec 700 psec < 1 nsec

slide-111
SLIDE 111

Low latency constructive rotation filter

RX TX = RX. ejɵ

a4 a3 a1 a2

d4 d1 d2 d3 PA 200 psec 100 psec 300 psec 0 psec RX

  • RX. F

RX.a1 RX.a2 RX.a3 RX.a4 TX RX ejɵ

Filtering in analog achieves constructive rotation within a nanosecond

RX(d1) RX(d2) RX(d4) RX(d3) 400 psec 700 psec < 1 nsec

slide-112
SLIDE 112

Implementation of FastForward

Block Diagram Full Duplex (FD) RX

Digital Constructive Filter

TX RX

Analog Constructive Filter (ACNF)

slide-113
SLIDE 113

Implementation of FastForward

PA ACNF TX RX FD

Antenna

Digital CNF Prototype Block Diagram Full Duplex (FD) RX

Digital Constructive Filter

TX RX

Analog Constructive Filter (ACNF)

slide-114
SLIDE 114

Implementation of FastForward

  • Built using WARP SDR platform, designed for 802.11

PA ACNF TX RX FD

Antenna

Digital CNF Prototype Block Diagram Full Duplex (FD) RX

Digital Constructive Filter

TX RX

Analog Constructive Filter (ACNF)

slide-115
SLIDE 115

Implementation of FastForward

  • Built using WARP SDR platform, designed for 802.11
  • Custom designed construct & forward filter boards & self-interference cancellation
  • BW 20MHz, 20dBm TX power

PA ACNF TX RX FD

Antenna

Digital CNF Prototype Block Diagram Full Duplex (FD) RX

Digital Constructive Filter

TX RX

Analog Constructive Filter (ACNF)

slide-116
SLIDE 116

Implementation of FastForward

  • Built using WARP SDR platform, designed for 802.11
  • Custom designed construct & forward filter boards & self-interference cancellation
  • BW 20MHz, 20dBm TX power
  • Built 2x2 MIMO FF Prototype

PA ACNF TX RX FD

Antenna

Digital CNF Prototype Block Diagram Full Duplex (FD) RX

Digital Constructive Filter

TX RX

Analog Constructive Filter (ACNF)

slide-117
SLIDE 117

Evaluation: Coverage and Capacity of FastForward

slide-118
SLIDE 118
  • Indoor office environment with five different floor plans
  • AP and relay are randomly but statically placed, and client

is placed at 25 different locations in each floorplan

Evaluation: Coverage and Capacity of FastForward

slide-119
SLIDE 119
  • Indoor office environment with five different floor plans
  • AP and relay are randomly but statically placed, and client

is placed at 25 different locations in each floorplan

  • Compared to:

Evaluation: Coverage and Capacity of FastForward

slide-120
SLIDE 120
  • Indoor office environment with five different floor plans
  • AP and relay are randomly but statically placed, and client

is placed at 25 different locations in each floorplan

  • Compared to:
  • AP only

Evaluation: Coverage and Capacity of FastForward

slide-121
SLIDE 121
  • Indoor office environment with five different floor plans
  • AP and relay are randomly but statically placed, and client

is placed at 25 different locations in each floorplan

  • Compared to:
  • AP only
  • AP + half duplex (HD) mesh router

Evaluation: Coverage and Capacity of FastForward

slide-122
SLIDE 122
  • Indoor office environment with five different floor plans
  • AP and relay are randomly but statically placed, and client

is placed at 25 different locations in each floorplan

  • Compared to:
  • AP only
  • AP + half duplex (HD) mesh router
  • AP + FF relay: same location as half duplex mesh router

Evaluation: Coverage and Capacity of FastForward

slide-123
SLIDE 123
  • Indoor office environment with five different floor plans
  • AP and relay are randomly but statically placed, and client

is placed at 25 different locations in each floorplan

  • Compared to:
  • AP only
  • AP + half duplex (HD) mesh router
  • AP + FF relay: same location as half duplex mesh router
  • Performance metrics
  • Best bitrate is experimentally estimated for each approach

at each client location

Evaluation: Coverage and Capacity of FastForward

slide-124
SLIDE 124
  • Indoor office environment with five different floor plans
  • AP and relay are randomly but statically placed, and client

is placed at 25 different locations in each floorplan

  • Compared to:
  • AP only
  • AP + half duplex (HD) mesh router
  • AP + FF relay: same location as half duplex mesh router
  • Performance metrics
  • Best bitrate is experimentally estimated for each approach

at each client location

Evaluation: Coverage and Capacity of FastForward

Bitrate of any approach Bitrate of AP + HD mesh router

Relative Gain =

slide-125
SLIDE 125

Does FF increase coverage?

Metric: Best bitrate for all the client positions Range of deployment: the farthest location at which the clients would see non-zero bitrate seen by mesh half duplex router.

slide-126
SLIDE 126

50 100 150 0.2 0.4 0.6 0.8 1

AP+ Half Duplex Mesh Routers AP only AP + FF Relay 2X2 MIMO PHY Layer Throughput in Mbps CDF

Does FF increase coverage?

Metric: Best bitrate for all the client positions Range of deployment: the farthest location at which the clients would see non-zero bitrate seen by mesh half duplex router.

slide-127
SLIDE 127

50 100 150 0.2 0.4 0.6 0.8 1

AP+ Half Duplex Mesh Routers AP only AP + FF Relay 2X2 MIMO PHY Layer Throughput in Mbps CDF

Does FF increase coverage?

Metric: Best bitrate for all the client positions Range of deployment: the farthest location at which the clients would see non-zero bitrate seen by mesh half duplex router. Clients with less than 60 Mbps

slide-128
SLIDE 128

50 100 150 0.2 0.4 0.6 0.8 1

AP+ Half Duplex Mesh Routers AP only AP + FF Relay 2X2 MIMO PHY Layer Throughput in Mbps CDF

Does FF increase coverage?

Metric: Best bitrate for all the client positions Range of deployment: the farthest location at which the clients would see non-zero bitrate seen by mesh half duplex router. 95% Clients with less than 60 Mbps

slide-129
SLIDE 129

50 100 150 0.2 0.4 0.6 0.8 1

AP+ Half Duplex Mesh Routers AP only AP + FF Relay 2X2 MIMO PHY Layer Throughput in Mbps CDF

Does FF increase coverage?

Metric: Best bitrate for all the client positions Range of deployment: the farthest location at which the clients would see non-zero bitrate seen by mesh half duplex router. 95% AP+ FF: 95% of locations get at least 60Mbps AP + Mesh Router: Only 30% of locations get at least 60Mbps Clients with less than 60 Mbps 30%

slide-130
SLIDE 130

Does FF increase capacity?

Metric: Relative Capacity Gain w.r.t. the AP + half duplex mesh router

slide-131
SLIDE 131

1 2 3 4 0.2 0.4 0.6 0.8 1

CDF Relative bitrate gains AP+ Half Duplex Mesh Routers AP only AP + FF Relay

Does FF increase capacity?

Metric: Relative Capacity Gain w.r.t. the AP + half duplex mesh router

slide-132
SLIDE 132

1 2 3 4 0.2 0.4 0.6 0.8 1

CDF Relative bitrate gains AP+ Half Duplex Mesh Routers AP only AP + FF Relay

Does FF increase capacity?

Metric: Relative Capacity Gain w.r.t. the AP + half duplex mesh router 2.3x

slide-133
SLIDE 133

1 2 3 4 0.2 0.4 0.6 0.8 1

CDF Relative bitrate gains AP+ Half Duplex Mesh Routers AP only AP + FF Relay

Does FF increase capacity?

Metric: Relative Capacity Gain w.r.t. the AP + half duplex mesh router 2.3x

Worse than Mesh relay

Our design achieves the 2.3x times the half duplex Mesh router c

slide-134
SLIDE 134

To Conclude

Forward signals, not packets!