Diversity Gain in Ultra Wideband Impulse Radio (UWB-IR)

Takahiro EZAKI  Tomoaki OHTSUKI  

IEICE TRANSACTIONS on Communications   Vol.E87-B   No.8   pp.2385-2390
Publication Date: 2004/08/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: LETTER
Category: Wireless Communication Technology
UWB-IR,  ST-UWB-IR,  TI-UWB-IR,  diversity,  

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In this paper, we propose a Time Interleave (TI)-Ultra Wideband (UWB)-Impulse Radio (IR) system where Nf monocycle pulses per information symbol are transmitted not continuously but discontinuously through the time interleaver to get more time diversity. Moreover, we compare the diversity gains of the UWB-IR systems on block fading channels with the fading block size q: the UWB-IR system with a single transmit antenna, the Space Time (ST)-UWB-IR system with Nt transmit antennas, and the TI-UWB-IR system with a single transmit antenna. Simulation results show that when the fading block size q = 1, the diversity gains of all the systems are same. When q is larger than or equal to 2 (q 2) and when both the number of transmit antennas Nt of the ST-UWB-IR system and the time interleaver size NTI of the TI-UWB-IR system are larger than or equal to q (Nt, NTI q), we show the following; both the ST-UWB-IR system and the TI-UWB-IR system achieve the same diversity gain that is constant regardless of Nt and NTI. On the other hand, when q 2 and when Nt and NTI < q, we show the following; when Nt = NTI, the ST-UWB-IR system and the TI-UWB-IR system get the same diversity gain; when Nt > NTI, the diversity gain of the ST-UWB-IR system is larger than that of the TI-UWB-IR system; and vice when Nt > NTI.