Variable Sub-Carrier Bandwidths in OFDM Systems
Variable Sub-Carrier Bandwidths in OFDM Systems
复制标题
OFDM 系统中的可变子载波带宽
DOI：
10.1109/vetecs.2007.387
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
R. Prasad
中科院分区：
文献类型：
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作者：
Suvra Shekhar Das;E. Carvalho;R. Prasad
正交频分复用（Orthogonal Frequency Division Multiplexing，OFDM）由于其高频谱利用率而被广泛应用于无线通信系统中，但其频率同步误差严重影响了其性能。这种误差是由于载波频率偏移和多普勒频率扩展而产生的。它们破坏了子载波间的正交性，并引入了载波间干扰（ICI）。干扰功率与接收信号强度和频率偏移量成比例。减少OFDM中ICI影响的几个建议使用非常复杂的信号处理，并且一些具有相关联的带宽效率损失。由于ICI与子载波带宽成反比，因此研究具有自适应子载波带宽的系统中的增益是有趣的。一个系统，它可以支持可变的子载波带宽，同时满足不同的ICI条件的需要进行比较与正常的OFDM系统，使用固定的载波带宽（FSB）。结果表明，当需要同时为不同接收信号强度和多普勒条件的用户提供服务时，VSB方案优于FSB OFDM系统。
Orthogonal frequency division multiplexing (OFDM) is widely used in wireless systems because of its high spectral efficiency, though it is known that it is highly vulnerable to frequency synchronization errors, which severely impede its performance. Such errors arise due to carrier frequency offset and Doppler frequency spread. They destroy the orthogonality among sub carriers and introduce inter carrier interference (ICI). The interference power is proportional to the received signal strength and amount of frequency offset. Several proposal to reduce the impact of ICI in OFDM use very complex signal processing and some have associated bandwidth efficiency loss. Since ICI is inversely proportional to the sub carrier bandwidth, it is interesting to investigate the gains in a system with adaptable sub carrier bandwidth. A system which can support variable sub carrier bandwidths simultaneously meeting the needs of different ICI conditions is compared against a normal OFDM system which uses fixed carrier bandwidth (FSB). Results show that the VSB schemes can be preferred over FSB OFDM system when users with different receive signal strength and Doppler condition have to be served simultaneously.