外文翻譯--超寬帶技術(shù)的短期或中期范圍內(nèi)的無(wú)線通信-文庫(kù)吧資料
2025-06-06 12:03本頁(yè)面
【正文】 vices at higher bandwidth but lower in cost and power consumption than currently available.2. Crowding in the spectrum that is segmented and licensed by regulatory authorities in traditional ways.3. The growth of highspeed wired access to the Internet in enterprises, homes, and public spaces.4. Shrinking semiconductor cost and power consumption for signal processing. Trends 1 and 2 favor systems that offer not just highpeak bit rates, but high spatial capacity1 as well, where spatial capacity is defined as bits/sec/squaremeter. Just as the telephone network enabled cellular telephony, Trend 3 makes possible highbandwidth, inbuilding service provision to lowpower portable devices using shortrange wireless standards like Bluetooth () and IEEE (). Finally, Trend 4 makes possible the use of signal processing techniques that would have been impractical only a few years ago. It is this final trend that makes UltraWideband (UWB) technology practical. When used as intended, the emerging short and mediumrange wireless standards vary widely in their implicit spatial capacities. For example : has a rated operating range of 100 meters. In the ISM band, there is about 80MHz of useable spectrum. Hence, in a circle with a radius of 100 meters, three 22MHz IEEE systems can operate on a noninterfering basis, each offering a peak overtheair speed of 11Mbps. The total aggregate speed of 33Mbps, divided by the area of the circle, yields a spatial capacity of approximately 1,000 bits/sec/squaremeter. , in its lowpower mode, has a rated 10meter range and a peak overtheair speed of 1Mbps. Studies have shown that approximately 10 Bluetooth “piconets” can operate simultaneously in the same 10meter circle with minimal degradation yielding an aggregate speed of 10Mbps [3]. Dividing this speed by the area of the circle produces a spatial capacity of approximately 30,000 bits/sec/squaremeter. is projected to have an operating range of 50 meters and a peak speed of 54Mbps. Given the 200MHz of available spectrum within the lower part of the 5GHz UNII band, 12 such systems can operate simultaneously within a 50meter circle with minimal degradation, for an aggregate speed of 648Mbps. The projected spatial capacity of this system is therefore approximately 83,000 bits/sec/squaremeter. systems vary widely in their projected capabilities, but one UWB technology developer has measured peak speeds of over 50Mbps at a range of 10 meters and projects that six such systems could operate within the same 10meter radius circle with only minimal deg
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