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Fundamental Limits of Wireless

High-speed wireless: Fast downloads by small devices

Wireless communication is limited by physics. Small devices must exploit environmental adversity to give them an advantage. The Fundamental Limits of Wireless (FLoW) project explores the limits of spatial diversity in wireless communication. Our work is primarily theoretical, based upon an understanding of the electromagnetic wave propagation of wireless signals.

The project has built upon a core of excellence within the Wireless Signal Processing (WSP) group and developing linkages between NICTA and the University of South Australia. FLoW was a joint research project between NICTA and Institute for Telecommunications Research, University of South Australia

Details

The project developed deep theoretical insights into the limits imposed on communication by the physical environment. Three PhD students graduated through this project Glenn Dickins (Dolby), Lei Qiu (NEC Melbourne) and Roy Timo (ITR, UniSA)

Project Staff:

  • Leader: Dr. Leif Hanlen, Senior Researcher, NICTA
  • Prof. Alex Grant, University of South Australia
  • Dr. David Smith, NICTA
  • Assoc. Prof. Thushara Abhayapala, Australian National University
  • Prof. Rod Kennedy, Australian National University
  • Mr. Roy Timo
  • Mr Lei Qiu
  • Mr Glenn Dickins

Major outcomes from project

Limit to Communication via Waves

How much information can be transmitted through a volume of space when the constraints are:
  • Volume V in 3D
  • Bandwidth W of signal in Hz
  • Carrier frequency F in Hz
  • Time T of transmission
  • Signal-to-noise ratio (power) in dB
The answer is given by a complex formula, but is related to the product of volume and cube of frequencies. The implication of this work is that broadband signals using spatial diversity are substantially better than either UWB (broadband) or MIMO (spatial) alone. Our result also implies that there is a finite amount of information which may be extracted through a region of space. More information in technical paper 

1-bit-below-optimal MIMO transmit using simple power allocation

We found that a uniform allocation of power to the N strongest branches of a multiple-input multiple-output system can achieve a data rate within 1bit/s/Hz of the true capacity -- ie. with extremely limited signaling, a simple MIMO transceiver can almost achieve the capacity of the most complex system. More information in technical paper

New results in cross-layer entropy

A series of results on the effect of movement, and entropy in a wireless ad-hoc system. This work was predominantly developed by PhD student Roy Timo.

Publications

  1. O. Nagy and L. W. Hanlen, “Capacity bounds for LTI channels,” in Australian Communications Theory Workshop, AusCTW, Christchurch, NZ, Jan. 2008, pp. 29–32.
  2. S. M. A. Salehin and L. W. Hanlen, “Dimensionality for two ring scattering model,” in Australian Communications Theory Workshop, AusCTW, Christchurch, NZ, Jan. 2008, pp. 12–16.
  3. L. Qiu and R. A. Kennedy, “Radio location using pattern matching techniques in fixed wireless communication networks,” in International Symposium on Communications and Information Technologies, Oct. 2007, pp. 1054–1059.
  4. D. B. Smith, “Orthogonal space-time block code optimization using varied input constellations,” in PIMRC, Sept. 2007.
  5. ——, “High rate quasi-orthogonal space-time block code designs for four transmit antennas,” in PIMRC, Sept. 2007.
  6. ——, “Improved quasi-orthogonal space-time block codes with hexagonal lattice modulation,” in SPAWC, June 2007.
  7. R. C. Timo, K. L. Blackmore, and J. Papandriopoulos, “Strong stochastic stability for dynamic source routing,” in Australasian TelecommunicationNetworks and Applications Conference (ATNAC), Dec. 2007.
  8. R. C. Timo, K. L. Blackmore, and L. W. Hanlen, “On the entropy rate of word-valued sources,” in Australasian Telecommunication Networks and Applications Conference (ATNAC), Dec. 2007.
  9. ——, “Strong stochastic stability for MANET mobility models,” in International Conference on Networks (ICON), Nov. 2007.
  10. L. W. Hanlen and T. D. Abhayapala, “Space-time-frequency degrees of freedom: Fundamental limits for spatial information,” in IEEE International Symposium on Information Theory, ISIT, 2007, p. .
  11. L. Qiu, R. A. Kennedy, and T. Betlehem, “Spatial degrees of freedom of correlated multipath,” in IEEE International Conference on Acoustics Speech and Signal Processing, ICASSP, 2007, p. .
  12. L. W. Hanlen and T. D. Abhayapala, “Bounds on space-time-frequency dimensionality,” in Australian Communications Theory Workshop, AusCTW, Feb. 5–7 2007, pp. 144–149.
  13. R. C. Timo, A. J. Grant, and L. W. Hanlen, “Source coding for a noiseless broadcast channel with partial receiver side-information,” in Australian Communications Theory Workshop, AusCTW, Feb. 5–7 2007, pp. 86–90.
  14. M. Zhang, A. D. S. Jayalath, T. D. Abhayapala, D. B. Smith, and C. Athaudage, “Compensation decoding of space-time-frequency block codes,” IEEE Communications Letters, vol. 11, no. 7, pp. 610–612, July 2007.
  15. D. B. Smith, “High-rate orthogonal space-time block code for four transmit antennas,” IEE Electronics Letters, vol. 43, no. 17, pp. 937–938, Aug. 2007.
  16. O. Nagy and L. W. Hanlen, “Lower bounds on mutual information for interleave division multiple access (IDMA),” National ICT Australia, Tech. Rep. PA006253, 2006.
  17. L. W. Hanlen, “Preliminary channel measurements: Ais rowing project,” National ICT Australia, Tech. Rep. PA006183, Sept. 2006.
  18. R. C. Timo, “On the ergodicity of a generalized random waypoint mobility model,” National ICT Australia, Tech. Rep. PA006113, 2006.
  19. ——, “On dimensionality and entropy in multiple antenna communication systems,” National ICT Australia, Tech. Rep., 2006.
  20. R. C. Timo, L. W. Hanlen, and K. L. Blackmore, “Variable-length encoders are ergodic thus random waypoint mobility model is stable,” Australian National University, Tech. Rep. PA006135, May 2006.
  21. D. B. Smith, “Method and apparatus for high rate orthogonal block coding,” NICTA invention disclosure, N06 017-INV, 2006.
  22. ——, “Method and apparatus for orthogonal block coding,” NICTA invention disclosure, N06 010-INV, 2006.
  23. P. Sadeghi, R. A. Kennedy, and T. D. Abhayapala, “Intrinsic finite dimensionality of random multipath fields,” in IEEE International Conference on Acoustics Speech and Signal Processing, ICASSP, May 2006, pp. IV–17–IV–20.
  24. R. R. Perera, T. S. Pollock, and T. D. Abhayapala, “Non-coherent Rayleigh fading MIMO channels: Capacity and optimal input,” in IEEE International Conference on Communications, ICC, Istanbul, Turkey, 11–15 June 2006.
  25. M. R. McKay, A. J. Grant, and I. B. Collings, “Largest eigenvalue statistics of double-correlated complex Wishart matrices and MIMO-MRC,” in IEEE International Conference on Acoustics Speech and Signal Processing, ICASSP, Toulouse, France, 14–18 May 2006.
  26. P. Sadeghi, T. D. Abhayapala, and R. A. Kennedy, “Directional random scattering MIMO channels: Entropy analysis and capacity optimization,” in IEEE International Conference on Communications, ICC, 2006.
  27. ——, “Intrinsic finite dimensionality of random multipath fields,” in IEEE International Conference on Acoustics Speech and Signal Processing, ICASSP, Toulouse, France, May 2006.
  28. L. Qiu and R. A. Kennedy, “Spatial correlation based degrees of freedom of multipath,” in IEEE Information Theory Workshop, ITW, 2006, p. .
  29. D. B. Smith, “Improved differential unitary space-time signal design for two to six transmit antennas,” in IEEE International Conference on Communications, ICC, Istanbul, Turkey, June 2006.
  30. L. W. Hanlen and R. C. Timo, “Intrinsic capacity of random scattered spatial communication,” in IEEE Information Theory Workshop, ITW, Oct. 22–27 2006, pp. 281–285.
  31. R. C. Timo, L. W. Hanlen, and K. L. Blackmore, “A lower bound on network layer control information,” in Newcom-Acorn workshop, Sept. 2006, p..
  32. D. B. Smith and L. W. Hanlen, “Novel unitary space-time signal design,” in IEEE Information Theory Workshop, ITW, Mar. 2006, pp. 327–331.
  33. A. J. Grant and L. W. Hanlen, “Sub-optimal power allocation for MIMO channels,” in IEEE International Symposium on Information Theory, ISIT, July 2006.
  34. M. Ruan, L. W. Hanlen, and M. C. Reed, “Spatially interpolated beamforming using discrete prolate spheroidal sequences,” in IEEE International Conference on Acoustics Speech and Signal Processing, ICASSP, vol. 3, France, May 14–19 2006, pp. 840–843.
  35. R. C. Timo and L. W. Hanlen, “MANETs: Routing overhead and reliability,” in IEEE Vehicular Technology Conference, VTC, Melbourne, Australia, May 7–10 2006, p. session 11B.
  36. G. N. Dickins, T. Betlehem, and L. W. Hanlen, “A stochastic MIMO model utilising spatial dimensionality and modes,” in IEEE Vehicular Technology Conference, VTC, May 7–10 2006, p. session 8H.
  37. L. W. Hanlen, R. C. Timo, and R. R. Perera, “On dimensionality for sparse multipath,” in Australian Communications Theory Workshop, AusCTW, Feb. 1–3 2006, pp. 123–127.
  38. R. Somaraju and L. W. Hanlen, “Uncertainty principles for signal concentrations,” in Australian Communications Theory Workshop, AusCTW, vol. 1, Feb. 1–3 2006, pp. 36–40.
  39. R. R. Perera, T. D. Abhayapala, and T. S. Pollock, “Gaussian inputs: Performance limits over non-coherent SISO and MIMO channels,” European Transactions on Telecommunications, p. in press, 2006.
  40. R. R. Perera, K. Nguyen, T. S. Pollock, and T. D. Abhayapala, “Capacity of non-coherent Rayleigh fading MIMO channels,” IEEE Transactions on Communications, p. in press, 2006.
  41. M. R. McKay, A. J. Grant, and I. B. Collings, “Performance analysis of MIMO-MRC in double-correlated Rayleigh environments,” IEEE Transactions on Communications, p. , 2006.
  42. D. B. Smith and T. D. Abhayapala, “Maximal ratio combining performance analysis in practical Rayleigh fading channels,” IEEE Transactions on Communications, p. , 2006.
  43. R. A. Kennedy, P. Sadeghi, T. D. Abhayapala, and H. M. Jones, “Intrinsic limits of dimensionality and richness in random multipath fields,” IEEE Transactions on Signal Processing, p. accepted, 2006.
  44. L. W. Hanlen and M. Fu, “Wireless communications with spatial diversity: A volumetric model.” IEEE Transactions on Wireless Communications, vol. 5, no. 1, pp. 133–142, Jan. 2006.
  45. R. Timo and L. W. Hanlen, “Entropy in ad-hoc networks: what price mobility?” Australian National University, Tech. Rep., Jan. 2005.
  46. D. B. Smith and T. D. Abhayapala, “Maximal ratio combining performance analysis in spatially correlated Rayleigh fading channels,” in Australian Communications Theory Workshop, AusCTW, 2–4 Feb. 2005, pp. 140–144.
  47. ——, “Maximal ratio combining performance analysis in spatially correlated Rayleigh fading channels with imperfect channel knowledge,” in Asia Pacific Communications Conference, 03–05 Oct. 2005, pp. 549–553.
  48. ——, “Generalised space-time modelling of Rayleigh MIMO channels,” in Australian Communications Theory Workshop, AusCTW, 2–4 Feb. 2005, pp.145–150.
  49. G. N. Dickins and L. W. Hanlen, “On finite dimensional approximation in MIMO,” in Asia Pacific Communications Conference, Oct. 2005, pp. 710–715.
  50. L. W. Hanlen and A. J. Grant, “On capacity of ergodic multiple-input multiple-output channels,” in 6th Australian Communications Theory Workshop, AusCTW, Brisbane, Australia, Feb. 2–4 2005, pp. 121–124.
  51. ——, “Optimal transmit covariance for MIMO channels with statistical transmitter side information,” in IEEE International Symposium on Information Theory, ISIT, Adelaide, Australia, Sept. 4–9 2005.
  52. B. Mondal, R. Heath Jr., and L. W. Hanlen, “Quantization on the Grassmann manifold: Applications to precoded MIMO wireless systems,” in IEEE International Conference on Acoustics Speech and Signal Processing, ICASSP, vol. 5, Pennsylvania, USA, Mar. 18–23 2005, pp. v/1025 – v/1028.
  53. L. Qiu, D. Jiang, and L. W. Hanlen, “Neural network prediction of radio propagation,” in 6th Australian Communications Theory Workshop, AusCTW, Brisbane, Australia, Feb. 2–4 2005, pp. 252–256.
  54. R. C. Timo, K. Blackmore, and L. Hanlen, “On entropy measures for dynamic network topologies: Limits to MANET,” in 6th Australian Communications Theory Workshop, AusCTW, Brisbane, Australia, 2005, pp. 89–94.
  55. G. N. Dickins, M. I. Y. Williams, and L. W. Hanlen, “On the dimensionality of spatial fields with restricted angle of arrival,” in IEEE International Symposium on Information Theory, ISIT, Adelaide, Australia, Sept. 5–9 2005.
  56. L. W. Hanlen and A. J. Grant, “Optimal transmit covariance for ergodic MIMO channels,” Oct. 2004, submitted to IEEE Transactions on Information Theory.
  57. G. Dickins and L. W. Hanlen, “Fast calculation of singular values for MIMO wireless systems,” in 5th Australian Communications Theory Workshop, AusCTW, Newcastle, Australia, Feb. 4–6 2004, pp. 185–190.
  58. L. W. Hanlen and M. Fu, “On point-wise models for MIMO systems,” in IEEE Global Communications Conference, Globecom, Dallas, USA, Nov. 29–3 Dec. 2004, pp. 76–80.
  59. L. W. Hanlen, A. J. Grant, and R. A. Kennedy, “On capacity for single-frequency spatial channels,” in IEEE Information Theory Workshop, ITW, San Antonio, USA, Oct. 24–27 2004, pp. 446–451.
  60. ——, “On the capacity of operator channels,” in 5th Australian Communications Theory Workshop, AusCTW, Newcastle, Australia, Feb. 4–6 2004, pp.23–27.