Picasso: Flexible RF and Spectrum Slicing This presentation is the introduction of paper that was presented as part of the main technical program at ACM SIGCOMM 2012, August. By Wonhong Jeon, CSI Lab, DGIST.

Agenda Description of the Problem WaveApps Description of the Problem Picasso: Flexible RF and Spectrum Slicing Their New Design and Main Factor Conclusions

Problem Protocol density is causing unlicensed spectrum fragmentation. Arbitrary: 제멋대로 Coexisting networks share arbitrary fragments of available spectrum which vary in time and space

What should we do? Objective: Transmit and Receive Simultaneously over Arbitrary Banks with a Single Antenna/RF Frontend 2.4GHz 2.5GHz

Also be used for radio sharing and coexistence • Current practice is to use a separate radio and antenna for each protocol. • Portable device real estate is limited, increasingly difficult to pack antenna. Such a capability could also be used for radio sharing and coexistence. separate ISM band protocols such as WiFi, WiFi-Direct, Zigbee, NFC, and Bluetooth.

Picasso: Flexible RF and Spectrum Slicing FDM으로 Tx/Tx, Rx/Rx 가능 하지만 Tx/Rx는 어떻게 처리해야할까? Case1: TX/TX Case2: RX/RX Case3: TX/RX ??

Why can’t the radio Tx/Rx simultaneously? TX level이 너무 크고 Rx level이 너무 작아 밴드에 먹히는 그림 그려주기!

Why can’t the radio Tx/Rx simultaneously? 다이나믹 레인지 = ADC 설명하자!!! TX level이 너무 크고 Rx level이 너무 작아 밴드에 먹히는 그림 그려주기! DAC ADC

How much self-interference cancellation is needed? Can we achieve enough cancellation to prevent receiver saturation? TX: DAC -> ANT 라지시그날 ANT -> ADC 스몰 시그날 근데 라지시그날이 스몰 시그날과 섞여 RX 안테나로 석여 들어오면 Digtal 부분에서 saturation이 일어난다. 그래서 14bit ADC 범위안에 들어올 수 있게 45dBm cancel해줘야한다. (Dgital부분 들어오기 전에) ?????????그럼 사이드밴드로브는 어떻게하고 센시티비티는 고려되지 않은듯… 가드밴드가 충분치 않으면 노이즈가 끼어서 센시티비티 낮아질거 같은데…

Recent Full-Duplex Wireless Technic J. Choi, M. Jain, K. Srinivasan, P. Levis, and S, Katti. (Stanford University) Achieving single channel, full duplex wireless communication. In ACM MobiCom, 2010. Let go to Picasso architecture. M. Jain, J. Choi, Tae Min Kim. (Stanford University) Practical, Real-time, Full-Duplex Wireless In ACM MobiCom, 2011.

Recent Full-Duplex Wireless Technic M. Jain, J. Choi, Tae Min Kim. (Stanford University) Practical, Real-time, Full-Duplex Wireless In ACM MobiCom, 2011. 결과1 인밴드 cancellation은 괜찮지만 멀어질 수록 별로다… 결과2 Active 소자라서 수신없어도 Leaking이 발생하여 노이즈처럼 낀다.

Their New Design Steven Hong, Jeffrey Mehlman, Sachin Katti. (Stanford University) Picasso: Flexible RF and Spectrum In ACM SIGCMM, 2012. Single Antenna Full-duplex even thus each frequency use different frequency. Leakage free passive cancellation Single Antenna Full-duplex Passive Cancellation

Their New Design

Main Key Factor: What is Circulator Enable Tx/Rx chain to share antenna Limited isolation (=15dB) between Tx/Rx

Main Key Factor: Passive Cancellation Canceller 그리고 전부 RF라인이라 안테나에 손만 가다가 데어도 임피던스가 바뀌며 delay line이 바꿔 오동작. 여기서 IQ다이그램 그려주고 왜 FIX delay가 안좋은지 설명 Passive and programmable delay lines are not readily available. -> limitation They have programmable attenuation.

How much cancellation in Picasso? No Saturation

Main Key Factor Baseband Transceiver and ADC/DAC

Main Key Factor Digital Filter Complexity vs. Interference Rejection

Performance Analysis WaveApps ISM Band ATN is samall size -> that mean it is passible to used in commercial.

Conclusions WaveApps Picasso Weakness - Circulator is too large for small device. - Passive canceller is too sensitive by touch. - 20th Digital filter is too complicated for small device. Picasso Advantage - They only use one antenna. - Passive canceller has no leakage. ISM Band ATN is samall size -> that mean it is passible to used in commercial.

Discussion Picasso is too similar with our idea which is presented at DGIST student workshop. - Let use the canceller at simultaneity Tx/Rx case. Q & A