TR2007-090

Hybrid Ultrawideband Modulations Compatible for Both Coherent and Transmit-Reference Receivers


    •  Zhao, S.; Orlik, P.; Molisch, A.F.; Liu, H.; Zhang, J., "Hybrid Ultrawideband Modulations Compatible for Both Coherent and Transmit-Reference Receivers", IEEE Transactions on Wireless Communications, ISSN: 1536-1276, Vol. 6, No. 7, pp. 2551-2559, July 2007.
      BibTeX Download PDF
      • @article{Zhao2007jul,
      • author = {Zhao, S. and Orlik, P. and Molisch, A.F. and Liu, H. and Zhang, J.},
      • title = {Hybrid Ultrawideband Modulations Compatible for Both Coherent and Transmit-Reference Receivers},
      • journal = {IEEE Transactions on Wireless Communications},
      • year = 2007,
      • volume = 6,
      • number = 7,
      • pages = {2551--2559},
      • month = jul,
      • issn = {1536-1276},
      • url = {http://www.merl.com/publications/TR2007-090}
      • }
  • MERL Contacts:
  • Research Areas:

    Electronics & Communications, Wireless Communications


This paper considers signaling schemes for heterogeneous ultrawideband communications networks that contain both coherent (rake) and transmitted-reference (TR) receivers. While coherent receivers are capable of receiving TR signals, they do so with a 3 dB penalty, because they cannot make use of the energy invested into the reference pulse. We propose a new signaling scheme that avoids this drawback, by encoding redundant information on the reference pulse. The resulting scheme does not affect the operation of a TR receiver, while recovering the 3 dB penalty and furthermore providing an additional 1.7 dB coding gain to a coherent uncoded binary scheme. This can be explained by interpreting the scheme as a trellis-coded modulation. We also provide an alternative implementation that can be viewed as a recursive systematic convolutional encoder. Combining this version further with a simple forward error correction encoder results in a concatenated code that can be decoded iteratively, providing a bit-error rate of 10-3 at 2.8 dB signal-to-noise ratio in additive white Gaussian noise. The convergence behavior of this iterative code is analyzed by using extrinsic information transfer charts.