Journal of Communications and Networks

The Korean Institute of Commucations and Information Sciences (한국통신학회)
권호 표지

Sub-band Spreading Technique for Adaptive Modulation in OFDM Systems

  • Jung, Bang-Chul (KAIST Institute for Information Technology Convergence) ;
  • Kwon, Jae-Kyun (School of Electrical Engineering and Computer Science, Yeungnam University) ;
  • Jin, Hu (School of Electrical Engineering and Computer Science, KAIST) ;
  • Sung, Dan-Keun (School of Electrical Engineering and Computer Science, KAIST)
  • Published : 2008.03.31
Download PDF
⟨ Previous Next ⟩

Abstract

We propose a sub-band spreading technique for adaptive modulation (AM) in orthogonal frequency division multiplexing (OFDM) systems in order to reduce signaling overheads and to average frequency selective fading channels causing different signal-to-noise ratio (SNR) values for subcarriers in each subband. The conventional sub-band based AM schemes can also reduce signaling overheads and complexity for allocating a resource per sub-band at a time. However, they may suffer from the channel variation in a sub-band when the sub-band size is larger than the channel coherence bandwidth (BW). The sub-band spreading at the transmitter enables the received symbols in each sub-band to have an identical reliability even in a frequency selective fading channel. We rigorously analyze the averaged SNR value at the receiver of the sub-band spreading system and the analyzed average SNR in a sub-band is used for an adaptation criterion. The proposed AM scheme outperforms the conventional sub-band based OFDM scheme without spreading, and it can yield better throughput performance than the conventional subcarrier based AM schemes when we consider the signaling overheads.

Keywords

References

  1. R. Van Nee and R. Prasad, OFDM for Wireless Multimedia Communications. Artech House Publishers, 2000
  2. IEEE, P802.16-REVd/D5, 'Part 16:Air interface for fixed broadband wireless access systems,' May 2004
  3. 3GPP, TR 25.814, 'Physical layer aspects for evolved UTRA (release 7),' Nov. 2005
  4. H. Steendam and M. Moeneclaey, 'Analysis and optimization of the performance of OFDM on frequency-selective time-selective fading channels,' IEEE Trans. Commun., vol. 47, pp.1811-1819, Dec. 1999 https://doi.org/10.1109/26.809701
  5. B. C. Jung, M. H. Sunwoo, and S. K. Oh, 'A new turbo-coded OFDM system using orthogonal code multiplexing,' in Proc. IEEE VTC 2002- spring, May. 2002, pp. 1448-1451
  6. T. Hishiyama, T. Shirai, M Itami, K. Itoh, and H. Aghvami, 'A study on controlling transmission power of carriers of OFDM signal combined with data symbol spreading in frequency domain,' IEICE Trans. Fundament., vol. E86-B, no. 8, pp. 2117-2124, Aug. 2003
  7. H. Atarashi, S. Abeta, and M. Sawahashi, 'Variable spreading factororthogonal frequency and code division multiplexing (VSF-OFCDM) for broadband packet wireless access,' IEICE Trans. Commun., vol. E86-B, no. 1, pp. 291-299, Jan. 2003
  8. N. Maeda, H. Atarashi, and M. Sawahashi, 'Performance comparison of channel interleaving methods in frequency domain for VSF-OFCDM broadband wireless access in forward link,' IEICE Trans. Commun., vol. E86-B, no. 1, pp. 300-313, Jan. 2003
  9. T. Keller and L. Hanzo, 'Adaptive multicarrier modulation: A convenient frame work for time-frequency processing in wireless communications,' Proc. IEEE, vol. 88, no.5, pp. 611-640, May 2000. https://doi.org/10.1109/5.849157
  10. R. G. Gallager, Information Theory and Reliable Communication. New York: John Wiley & Sons, 1968
  11. D. Hughes-Hartogs, 'Ensemble modem structure for imperfect transmission media,' U.S. Patents Nos., 4,679,227, July 1987; 4,731,816, Mar. 1988; and 4,833,796, May 1989
  12. J. A. C. Bingham, 'Multicarrier modulation for data transmission: An idea whose time has come,' IEEE Commun. Mag, vol. 28, no.4, pp. 5-14, Apr. 1990 https://doi.org/10.1109/35.54342
  13. P. S. Chow, J. M. Cioffi, and J. A. C. Bingham, 'A practical discrete transceiver loading algorithm for data transmission over spectrally shaped channels,' IEEE Trans. Commun, vol. 43, no.2/3/4, pp. 773-775, Feb./ Mar./Apr. 1995 https://doi.org/10.1109/26.380108
  14. R. F. H. Fischer, J. B. Huber, 'A new loading algorithm for discrete multitone transmission,' in Proc. IEEE GLOBECOM, Nov. 1996, pp. 724-728
  15. B. S. Krongold, K. Ramchandran, and D. L. Jones, 'Computationally efficient optimal power allocation algorithms for multicarrier communication systems,' IEEE Trans. Commun, vol. 48, no. 1, pp. 23-27, Jan. 2000 https://doi.org/10.1109/26.818869
  16. M. Lei and P. Zhang, 'Subband bit and power loading for adaptive OFDM,' in Proc. IEEE VTC 2003-fall, vol. 3, Oct. 2003, pp. 1482-1486
  17. K. Fazel and S. Kaiser, Multi-Carrier and Spread Spectrum Systems. Wiley, 2003
  18. B. McNair, L. J. Cimini, Jr., and N. R. Sollenberger,'Performance of an experimental 384 kb/s 1900 MHz OFDM radio link in a wide-areae highmobility environment,' in Proc. IEEE VTC 2001-fall, Oct. 2001, pp. 475- 478