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Abstract
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| "The introduction of new generations of mobile communication systems, such as the current 3G and the future 4G, along with the provision of multimedia services, has exponentially increased the number of users demanding higher data rate. This fact has aroused the interest in studying possible solutions to improve system performance without making use of new frequency band allocations in the already crowded frequency spectrum. As an interesting option, wireless communication systems with Multiple-Inputs and Multiple-Outputs (MIMO) in which many antennas are used for transmission and reception have received increasing attention from the research community over the past few years (Paulraj et al., 2004, Goldsmith et l., 2003). On the other hand, the OFDM (Orthogonal Frequency Division Multiplexing) technique has been adopted for the transmission of signals over wireless channels in several standards of systems such as DAB, DVB-T and IEEE 802.11a/g for LAN and IEEE 802.16a, for MAN. Moreover, this technique is presented as a potential candidate for the 4G mobile communications. Regarding this, different studies and schemes have been realized to use MIMO systems with OFDM as in (Sampath et al, 2002). In the last two years, the standard IEEE 802.11n is been eveloping to introduce MIMO with OFDM in WLAN systems. The performance achieved with a MIMO system depends on factors such as the propagation channel, the space-time processing algorithm, or the number and characteristics of antennas. In order to see MIMO systems deployed over real communication networks, a thorough knowledge of the MIMO channel is a must. Therefore, a significant amount of measurements under real conditions and their detailed analysis are needed. Furthemore, in order to evaluate the performances of MIMO systems regarding the type of antenna array and channel propagation characteristics, two MIMO-OFDM measurement systems have been created in Universidad Politécnica de Madrid (UPM) and described in this chapter." | |
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International
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Si |
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Book Edition
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0 |
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Book Publishing
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IN-TECH |
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ISBN
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978-953-307-061-2 |
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Series
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Book title
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Advances in Measurement Systems |
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From page
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393 |
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To page
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416 |