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Differentially Detection in UWB Communicatio Systems without Reference Transmission

Rahmati, Mojtaba | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39555 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Nasiri Kenari, Masoumeh
  7. Abstract:
  8. In recent years, UWB multiple access communication systems have received a great attention due to its many advantages. The most important advantages of a UWB system can be summarized as its high data rates, low power consumption, fading immunity and high precision routing. One of the important problems in a UWB system implementation is in its receiver part in which in order to use a coherent RAKE receiver, the channel coefficients have to be estimated. Since UWB channel is a dense multipath fading channel with a very high number of resolvable paths, the channel coefficient estimation based on using training sequence is very complicated. To resolve this problem, transmit reference (TR) schemes are previously introduced in which a reference pulse along with data pulse is transmitted then the received reference pulse is considered as a noisy estimation of the channel impulse response which is used as a template in correlator receiver. However, the TR-UWB systems have their own problems; in these systems, some resources like rate, power, or both have to be dedicated in transmitting the reference pulse. In this thesis to reduce the above problems, we propose new transmitting and receivnig procedures for multi-rate UWB systems based on differentially encoded schemes. In our proposed scheme, the data is differentilly encoded in a multirate UWB system and then transmitted. Then, in each signaling interval, the template, required for the correlator used at the receiver front, is estimated using the received signal of the previous signal interval First, we analytically evaluate the eperformance of our proposed scheme in a single user environment in AWGN and multipath fading channels and compare the results with those of TR-UWB communicaton systems. We also provide som simulation performance evaluations which confirm our analytical derivations. Our both analytical and simulation results indicate the superiority of our propsed schemes compared to the TR-UWB systems, especially for multirate cases. We also analyze the performancee of the eproposed system in the presence of multi user interference based on both analytical derivations and simulations. Again, simulation confirms our analytical analysis. Further, our results indicate good performance of our proposed scheme.

  9. Keywords:
  10. Gaussian Noise ; Fading Channel ; Transmitted Reference System ; Ultra Wide Band (UWB)Communication ; Rake Receiver ; Differentially Transmission

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