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The increased demand for mobile broadband communications has led to the development of broadband wireless standards such as UMTS, W-CDMA and HSPA. Even though these technologies have been deployed in most of the developed parts of the world, they have not yet achieved the same market penetration as their predecessors, mainly because of their high cost. Additionally, these technologies are incapable of maintaining reliable high-data rates (>1 Mb/s) at vehicular speeds. Both of the above shortcomings are successfully addressed by the latest wireless technologies (for example, IEEE 802.16e) and those expected to enter the market from 2010, such as LTE, LTE-Advanced and 802.16m. Common practice in modem networks is the incorporation of multiple antenna technologies (MIMO) to improve spectral efficiency and reliability (thus reducing cost) through an improved physical layer. |
