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LTE and LTE-advanced are OFDM-based radio access technology. OFDM outshone CDMA in early comparisons when the simple but way suboptimal rake was still the default receiver in CDMA. Since then it has been realized that with advanced receivers both RATs reach similar spectrum efficiency. Now with even more advanced features in horizon, it may be time to re-evaluate which RAT fits better with multipoint broadcasting, ever increasing demand for reference signals, continuous and low-delay feedback, MIMO demodulation complexity, etc. Ultimately, the question of interest is, will higher spectral efficiency be available beside OFDM-based RAT?

We, along with other colleagues in the wireless profession, have been looking for answers. Some very interesting ideas are being developed.

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LTE 和 LTE-advanced是基于OFDM的无线接入技术。在LTE的早期，OFDM的确性能上胜过CDMA，然而当时的CDMA仍在采用简单但远非最优的rake 接收器。现在人们逐渐认识到在采用先进接收器的基础上，两种无线接入技术的频谱效率不分上下。伴随着更多先进技术和功能的涌现，重新审视无线接入技术的时机也许已经成熟。哪一种技术能够更好地融合多点传播、日益增长的参考信号、连续且低滞后的反馈、MIMO解调的复杂度等方面的要求？最相关的问题是，有没有可能实现高于基于OFDMde无线接入技术的频谱效率？

青山无线正在与无线领域里的同行一起探索答案，并在开发和充实若干新颖而富有潜力的设想。