Full-Duplex Radio Communications. Mikko Valkama Dept. Electronics and Communications Engineering

Transcription

1 Full-Duplex Radio Communications Mikko Valkama Dept. Electronics and Communications Engineering

2 Some Background One driving force in wireless communications research is the lack of spectrum especially in the typical cellular mobile radio frequency range of ~700MHz 3.5GHz or so radiokanava

3 Some Background, contd radiokanava Both academia and industry seeking ways how to improve the efficiency of frequencies already in use Link-level: waveform research ( better modulation and coding schemes, etc) System-level: radio resource management, device coordination, shared spectrum,

4 Full-Duplex In two-way communications, both devices are transmitting and receiving Classical solutions Time-division duplexing (TDD): transmission and reception on same frequency but in different time slots Frequency-division duplexing (FDD): transmitting and receiving simultaneously but on different frequencies TDD is used e.g. in WLAN, FDD in mobile cellular radio

5 Full-Duplex, cont d Interestingly, if transmitting and receiving simultaneously on single frequency, one could double the spectral efficiency of the system But is it feasible? Massive TX signal will kill the RX when co-existing on same frequency? Maybe. Maybe not

6 Full-Duplex, cont d Yes, TX signal is big, typically in the order of +20dBm +50dBm depending on the system While typical RX sensitivity requirement is in the order of -100dBm But since TX signal is known inside the transceiver, it can in principle be subtracted!!

7 Full-Duplex, cont d Assuming different TX and RX antennas, feasible isolation between them is perhaps ~ 30-50dB Then at RX input, we can attenuate the self-interference further by subtracting the TX RF waveform properly => max 40-50dB more Further suppression through final digital cancellation => 20-40dB?

8 Full-Duplex and Scientific Novelty So in principle it is possible but massive implementation challenges Quite cross-disciplinary area combining Antennas and electromagnetics RF circuits Digital signal processing Communication theory Also very recent/new idea, globally, lots of potential Research started only 3-4 years ago Stanford and Rice

9 Full-Duplex and Wireless Industry Lack of spectrum drives the industry Big interest currently to full-duplex; one of the very few true radical innovations in wireless communications physical layer Esp device vendors and silicon companies..in the end, maybe not macro devices but small cells and other enhanced local area solutions!

10 Full-Duplex and Our Research Research team comprising of Aalto and TTY, principal investigators R.Wichman and M.Valkama Aalto: Dept Signal Processing and Dept Radio Science and Engineering TTY: Dept Electronics and Communications Engineering Funding from Academy of Finland and Tekes Companies: Nokia, NSN, Renesas Mobile, Elektrobit

11 Full-Duplex and Our Research Target to develop Novel antenna solutions Novel RF processing Novel digital signal processing solutions to enable small and cost-efficient full-duplex transceivers In addition to above, working also on the systems side; how to best capitalize the potential of fullduplex capable devices in e.g. mobile cellular networks

12 International Collaboration Direct research collaboration and long-term researcher exchange with Rice University, Houston, US Arizona State University, Tempe, US Kyoto University, Japan University of Tokyo, Japan Technical challenges are so big that cannot be solved alone! There s always room also for good new people!

13 Selected First Outcomes D. Korpi, T. Riihonen, V. Syrjälä, L. Anttila, M. Valkama, and R. Wichman, Full-duplex transceiver system calculations: Analysis of ADC and linearity challenges, submitted and under review in IEEE Trans. Wireless Communications. D. Korpi, S. Venkatasubramanian, T. Riihonen, L. Anttila, S. Tretiakov, M. Valkama, and R. Wichman, 'Advanced selfinterference cancellation and multiantenna techniques for full-duplex radios, submitted and under review in Asilomar Conf. Signals, Syst., Computers, Pacific Grove, CA, November T. Riihonen, R. Wichman, Analog and Digital Self-Interference Cancellation in Full-Duplex MIMO-OFDM Transceivers with Limited Resolution in A/D Conversion, in Proc. Asilomar Conf. Signals, Syst., Computers, Pacific Grove, CA, November