Bandwidth Efficient Multi-carrier System for Wireless Channels

本文提出的研究工作探讨了基于多载波技术为未来无线系统开发带宽高效通信方法的方法。在过去十年中，无线通信经历了爆炸式增长，对更高的数据速率的需求，以适应新的服务。这导致了过多的标准被采用和商业化。在通信和无线研究界，大量的努力致力于开发带宽高效的信令方案，以在不利的无线环境中传输如此高的数据速率，其中传输性能受到频率选择性衰落，干扰和噪声的严重损害。宽带码分多址（WCDMA）技术已被用于第三代无线移动系统，以适应几兆/秒数量级的数据速率，正交频分复用（OFDM）技术已成为下一代无线系统研究的重要竞争者。OFDM方案基于将数据分成几个流，然后将这些流发送到单独的载波上的概念，其中相邻载波的频率间隔等于每个数据流的速率。在伦敦大学学院，我们开发了一种方案，这种频率分离可以减半，因此带宽可以翻倍。这种方案在要传输的数据的性质方面有其局限性，并且非常容易受到信道缺陷的影响。随后，我们对更有效的调制和解调方案进行了初步研究，该方案可以进一步减少载波分离，从而提供更高的带宽效率优势。通过基本的分析工作和详细的建模/仿真，证明了该方案的可行性。在这个提案中，我们的目标是对我们提出的方案进行进一步的研究，并评估其优点、缺点和局限性。这项工作将通过详细的分析研究和数学建模，以及使用数字信号处理（DSP）技术的基本实现来进行。

The research work proposed here investigates the means to develop a bandwidth efficient communication method, for future wireless systems, based on multicarrier techniques. In the last decade wireless communications have experienced an explosive growth with the demand for higher data rates to accommodate new services. This led to a plethora of standards being adopted and commercialised. In the communications and wireless research communities, substantial effort has been dedicated to develop bandwidth efficient signalling schemes to convey such high data rates in the adverse wireless environment, where transmission performance is severely compromised by frequency selective fading, interference and noise. Wideband code division multiple access (WCDMA) techniques have been adopted for third generation wireless mobile systems in order to accommodate data rates of the order of few Mbits/s and orthogonal frequency division multiplexing (OFDM) techniques have become serious contenders studied for future generation wireless systems. The OFDM schemes are based on the concept of dividing the data into several streams and then sending the streams on separate carriers, where the adjacent carriers have a frequency separation equal to the rate of each of the data streams. At UCL we developed a scheme where such frequency separation can be halved and therefore the bandwidth can be doubled. Such scheme has its limitation in terms of the nature of the data to be transmitted and is very susseptible to channel imperfections. Following that we carried out initial studies on a more efficient scheme of modulation and demodulation where the carrier separation can be further reduced, thereby providing even higher bandwidth efficiency advantages. The feasibility of this proposed scheme has been proven through basic analytical work and detailed modelling/simulation. In this proposal we aim to carry out further studies of our proposed scheme and assess its advantages, disadvantages and its limitations. This work will be carried out through detailed analytical studies and mathematical modelling, as well as, basic implementation using Digital Signal Processing (DSP) techniques.