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

How to relay while receiving ? 20 dBm • Relaying & receiving  Amplify to MAX 0 dBm Simultaneous TX and RX on the same frequency Relay -70dBm • Use recent work on full duplex Noise • Receive signal, amplify and -90 dBm Receiver Noise floor simultaneously relay Relay received Relay transmitted Simultaneously Relayed 20dB SNR Full duplex Full duplex TX and RX RX RX RX TX TX TX RF & Digital Processing RF & Digital Processing Max Amplify AP Client Direct

How to relay while receiving ? 20 dBm • Relaying & receiving  Amplify to MAX 0 dBm Simultaneous TX and RX on the same frequency Relay -70dBm • Use recent work on full duplex Noise • Receive signal, amplify and -90 dBm Receiver Noise floor simultaneously relay Relay received Relay transmitted Simultaneously Relayed 20dB SNR Full duplex Full duplex TX and RX RX RX RX TX TX TX RF & Digital Processing RF & Digital Processing Max Amplify Are we done? No, this design has two problems: AP • Amplifies noise Client Direct • Creates destructive interference

Challenge 1: Noise Amplification

Challenge 1: Noise Amplification Transmit -80dBm Direct Direct 10dB SNR Source (AP) -90 dBm Noise floor Transmitted Destination Received

Challenge 1: Noise Amplification Transmit 20dB SNR -80dBm Direct Direct 10dB SNR Source (AP) -90 dBm Noise floor Transmitted Destination Received

Challenge 1: Noise Amplification -70dBm -90 dBm Receiver Noise floor Relay received Transmit 20dB SNR -80dBm Direct Direct 10dB SNR Source (AP) -90 dBm Noise floor Transmitted Destination Received

Challenge 1: Noise Amplification 20 dBm 0 dBm Amplify to MAX (90 dB ) Relay -70dBm Noise -90 dBm Receiver Noise floor Relay received Relay transmitted Transmit 20dB SNR -80dBm Direct Direct 10dB SNR Source (AP) -90 dBm Noise floor Transmitted Destination Received

Challenge 1: Noise Amplification 20 dBm 0 dBm Amplify to MAX (90 dB ) Relay -70dBm Noise -90 dBm Receiver Noise floor Relay received Relay transmitted Transmit 30 dB SNR 20dB SNR -80dBm Direct Direct 10dB SNR Source (AP) -90 dBm Noise floor Transmitted Destination Received

Challenge 1: Noise Amplification 20 dBm 0 dBm Amplify to MAX (90 dB ) Relay -70dBm Noise -90 dBm Receiver Noise floor Relay received Relay transmitted Transmit 30 dB SNR 20dB SNR -60dBm -80dBm -80dBm Direct Relay Direct Noise 10dB SNR Source (AP) -90 dBm Noise floor Transmitted Destination Received

Challenge 1: Noise Amplification 20 dBm 0 dBm Amplify to MAX (90 dB ) Relay -70dBm Noise -90 dBm Receiver Noise floor Relay received Relay transmitted Transmit 30 dB SNR 20dB SNR -60dBm -80dBm -80dBm Direct Relay Direct Noise 10dB SNR Source (AP) -90 dBm Noise floor Transmitted Destination Received

Challenge 1: Noise Amplification 20 dBm 0 dBm Amplify to MAX (90 dB ) Relay -70dBm Noise -90 dBm Receiver Noise floor Relay received Relay transmitted Transmit 30 dB SNR 20dB SNR -60dBm -80dBm -80dBm Direct Relay Direct Noise 10dB SNR Source (AP) -90 dBm Noise floor Transmitted Destination Received Amplified noise destroys direct signal

Challenge 2: Destructive Interference AP Direct Direct -90 dBm Noise floor Destination Received

Challenge 2: Destructive Interference AP Direct Direct -90 dBm Noise floor Destination Received Im Re

Challenge 2: Destructive Interference AP Direct Direct -90 dBm Noise floor Destination Received Im Direct Re

Challenge 2: Destructive Interference Full Duplex Relayed RX TX Max Amplify AP Direct Direct -90 dBm Noise floor Destination Received Im Direct Re

Challenge 2: Destructive Interference Full Duplex Relayed RX TX Max Amplify AP Direct Direct -90 dBm Noise floor Destination Received Im Direct Re Relayed

Challenge 2: Destructive Interference Full Duplex Relayed RX TX Max Amplify AP Direct + Relayed Direct -90 dBm Noise floor Destination Received Im Direct Re Relayed

Challenge 2: Destructive Interference Full Duplex Relayed RX TX Max Amplify AP Direct + Relayed Direct Total -90 dBm Noise floor Destination Received Im Im Direct Re Re Total Relayed Destructive Interference

Construct and Forward relaying to tackle these two chall llenges

Construct and Forward relaying Full Duplex Full Duplex Relayed RX RX TX TX Max Amplify AP Direct

Construct and Forward relaying Full Duplex Full Duplex Relayed RX RX TX TX Construct & Forward Max Amplify filtering AP Direct Basic Idea: Filter the received signal such that noise isn’t amplified and signals add constructively at the destination

Construct and Forward filter abstraction Full Duplex Full Duplex RX RX TX TX Construct & Forward Naïve Amplify RX TX Construct & Forward filtering filtering

Construct and Forward filter abstraction Full Duplex Full Duplex RX RX TX TX Construct & Forward Naïve Amplify RX TX Construct & Forward filtering filtering RX TX Constructive Constructive amplification rotation

Construct and Forward filter abstraction Full Duplex Full Duplex RX RX TX TX Construct & Forward Naïve Amplify RX TX Construct & Forward filtering filtering RX TX Constructive Constructive amplification rotation . e jɵ RX . A = TX Received Constructive Constructive Relayed signal amplification rotation signal at relay

Construct and Forward filter abstraction Full Duplex Full Duplex RX RX TX TX Construct & Forward Naïve Amplify RX TX Construct & Forward filtering filtering RX TX Constructive Constructive amplification rotation . e jɵ RX . A = TX Received Constructive Constructive Relayed signal amplification rotation signal at relay How does Construct and Forward calculate A & e jɵ ?

Constructive amplification A

Constructive amplification A 20 dBm -90 dBm Noise floor Source Transmitted Destination Received

Constructive amplification A 20 dBm 90 dB loss -90 dBm Noise floor Source Transmitted Destination Received

Constructive amplification A -70dBm -90 dBm Receiver Noise floor Relay received 20 dBm 90 dB loss -90 dBm Noise floor Source Transmitted Destination Received

Constructive amplification A -70dBm -90 dBm Receiver Noise floor Relay received 80 dB loss 20 dBm 90 dB loss -90 dBm Noise floor Source Transmitted Destination Received

Constructive amplification A 10 dBm -10 dBm Amplify by 80 dB Relay -70dBm Noise -90 dBm Receiver Noise floor Relay received Relay Transmitted 80 dB loss 20 dBm 90 dB loss -90 dBm Noise floor Source Transmitted Destination Received

Constructive amplification A 10 dBm -10 dBm Amplify by 80 dB Relay -70dBm Noise -90 dBm Receiver Noise floor Relay received Relay Transmitted Relayed 80 dB loss -70dBm 20 dBm 90 dB loss -90dBm Relay -90 dBm Noise Noise floor Source Transmitted Destination Received

Constructive amplification A 10 dBm -10 dBm Amplify by 80 dB Relay -70dBm Noise -90 dBm Receiver Noise floor Relay received Relay Transmitted Relayed 80 dB loss -70dBm 20 dBm 90 dB loss -90dBm Relay -90 dBm Noise Noise floor Source Transmitted Destination Received

Constructive amplification A 10 dBm -10 dBm Amplify by 80 dB Relay -70dBm Noise -90 dBm Receiver Noise floor Relay received Relay Transmitted Relayed 80 dB loss -70dBm 20 dBm 90 dB loss -90dBm Relay -90 dBm Noise Noise floor Source Transmitted Destination Received Constructive amplification factor A can be at most the propagation loss from relay to destination

Constructive rotation e jɵ Full Duplex Relayed RX TX Construct & Forward Filtering AP Direct

Constructive rotation e jɵ Full Duplex Relayed RX TX Construct & Forward Filtering AP Direct Im Direct Re Amplify only relay

Constructive rotation e jɵ Full Duplex Relayed RX TX Construct & Forward Filtering AP Direct Im Im Direct Re Re Amplify only Amplify relay total only relay

Constructive rotation e jɵ Full Duplex Relayed RX TX Construct & Forward Filtering AP Direct Constructive Im relay Im Im Direct Direct Re Re Re Amplify only Amplify relay total only relay

Constructive rotation e jɵ Full Duplex Relayed RX TX Construct & Forward Filtering AP Direct Constructive relay total Constructive Im relay Im Im Direct Direct Re Re Re Amplify only Amplify relay total only relay

Constructive rotation e jɵ Full Duplex Relayed RX TX Construct & Forward Filtering AP Direct Constructive relay total Constructive Im Constructive relay Im Im Direct Direct rotation by e jɵ Re Re Re e jɵ Amplify only Amplify Amplify relay total only relay only relay

Constructive rotation e jɵ Full Duplex Relayed RX TX Construct & Forward Filtering AP Direct Constructive relay total Constructive Im Constructive relay Im Im Direct Direct rotation by e jɵ Re Re Re e jɵ Amplify only Amplify Amplify relay total only relay only relay Constructive rotation e jɵ should be as close as possible to the phase difference between the direct and the relay path’s channels

Summary: Construct and Forward filter Full Duplex Full Duplex RX RX TX TX Construct & Forward Naïve Amplify RX TX Construct & Forward filtering filtering RX TX Constructive Constructive amplification rotation . e jɵ RX . A = TX Received Constructive Constructive Relayed at relay Amplification Rotation

Summary: Construct and Forward filter Full Duplex Full Duplex RX RX TX TX Construct & Forward Naïve Amplify RX TX Construct & Forward filtering filtering RX TX Constructive Constructive amplification rotation . e jɵ RX . A = TX Received Constructive Constructive Relayed at relay Amplification Rotation Propagation loss from relay to destination

Summary: Construct and Forward filter Full Duplex Full Duplex RX RX TX TX Construct & Forward Naïve Amplify RX TX Construct & Forward filtering filtering RX TX Constructive Constructive amplification rotation . e jɵ RX . A = TX Received Constructive Constructive Relayed at relay Amplification Rotation Propagation loss from Align the phases of the relay to destination relay path and direct path at the destination

High latency leads to inter-symbol interference AP

High latency leads to inter-symbol interference Direct AP

High latency leads to inter-symbol interference Direct AP Direct CP CP Symbol2 Symbol1

High latency leads to inter-symbol interference Direct AP Full Duplex Full Duplex RX RX TX TX Direct CP CP Symbol2 Symbol1 Construct & Forward Naïve Amplify Filtering

High latency leads to inter-symbol interference Direct AP Relayed Full Duplex Full Duplex RX RX TX TX Direct CP CP Symbol2 Symbol1 Construct & Forward Naïve Amplify Filtering

High latency leads to inter-symbol interference Direct AP Relayed Full Duplex Full Duplex RX RX TX TX Direct CP CP Symbol2 Symbol1 Construct & Forward Naïve Amplify Filtering Δ t Relayed CP CP Symbol2 Symbol1

High latency leads to inter-symbol interference Direct AP Relayed Full Duplex Full Duplex RX RX TX TX Direct CP CP Symbol2 Symbol1 Construct & Forward Naïve Amplify Filtering Δ t Relayed CP CP Symbol2 Symbol1 Symbol1 interferes with Symbol2

High latency leads to inter-symbol interference Direct AP Relayed Full Duplex Full Duplex RX RX TX TX Direct CP CP Symbol2 Symbol1 Construct & Forward Naïve Amplify Filtering Δ t Relayed CP CP Symbol2 Symbol1 Symbol1 interferes with Symbol2 Minimize the latency of Construct & Forward filter to avoid inter symbol interference

High latency leads to inter-symbol interference Direct AP Relayed Full Duplex Full Duplex RX RX TX TX Direct CP CP Symbol2 Symbol1 Construct & Forward Naïve Amplify Filtering Δ t Relayed CP CP Symbol2 Symbol1 Symbol1 interferes with Symbol2 Minimize the latency of Construct & Forward filter to avoid inter symbol interference RX TX Constructive Constructive Amplification Rotation

High latency leads to inter-symbol interference Direct AP Relayed Full Duplex Full Duplex RX RX TX TX Direct CP CP Symbol2 Symbol1 Construct & Forward Naïve Amplify Filtering Δ t Relayed CP CP Symbol2 Symbol1 Symbol1 interferes with Symbol2 Minimize the latency of Construct & Forward filter to avoid inter symbol interference RX TX Constructive Constructive Amplification Rotation Negligible Latency

High latency leads to inter-symbol interference Direct AP Relayed Full Duplex Full Duplex RX RX TX TX Direct CP CP Symbol2 Symbol1 Construct & Forward Naïve Amplify Filtering Δ t Relayed CP CP Symbol2 Symbol1 Symbol1 interferes with Symbol2 Minimize the latency of Construct & Forward filter to avoid inter symbol interference RX TX Constructive Constructive Amplification Rotation How do we achieve this block with Negligible Latency minimum latency?

Low latency constructive rotation filter TX = RX. e jɵ RX Constructive rotation ( e jɵ )

Low latency constructive rotation filter TX = RX. e jɵ RX Constructive rotation ( e jɵ ) RX