Multiple Description Coding with Correlating Transforms for Multiple Antenna Wireless Systems

多描述编码（multipledescription coding， MDC）是在通信系统中为多媒体传输提供容错能力且效率降低相对较小的有效方法，它假设在发送端和接收端之间存在多个独立的信道，每个信道都可能暂时关闭或经历突发错误。使用MDC可以生成多个编码流（称为描述），并通过不同的通道传输。在目的地，如果接收到的所有流都没有错误，那么信号就可以以最高的保真度重建。然而，如果仅以可用的形式接收到一个或几个描述，接收器仍然可以重建一个可接受的信号。迄今为止，所有的多重描述编码方法都假定发射器和接收器之间的信道模型为非开关；每条链路要么中断，在这种情况下，传输的符号或数据包完全丢失，要么正常工作，在这种情况下，数据包被毫无错误地接收。这种模式适用于Internet传输，但不适用于无线信道。本研究用瑞利衰落模型等无线信道模型代替了并行独立的通断信道模型。通信是通过信道上的多个发射和接收天线进行的。在这些模型中，任何接收天线的信号都是来自每个发射天线的发射信号的叠加。因此，即使接收端的描述是完全独立的，每个天线接收到的信号也会包含来自每个描述的一些信息。这项研究包括为这些信道找到最佳的多描述编码策略，这种方案的理论限制，以及它可以实现的效率。

An effective way of providing error resilience for multimedia transmission in acommunication system with a relatively small reduction in efficiency is multipledescription coding (MDC), which assumes the existence of multiple independentchannels between the transmitter and receiver, each of which can be temporarilydown or can experience burst errors. With MDC several coded streams, calleddescriptions, are generated and transmitted over different channels. At thedestination, if all of the streams are received error free, than the signal canbe reconstructed at its highest level of fidelity. However, if only one or a fewdescriptions are received in a usable form, the receiver can still reconstructan acceptable signal. All multiple description coding methods to date assume anon-off channel model between the transmitter and the receiver; each link iseither broken, in which case the transmitted symbols, or packets, are lostcompletely, or it functions properly, in which case the packets are receivedfree of errors. This model is appropriate for Internet transmission, but it isnot appropriate for wireless channels.This study replaces the parallel independent on-off channel model with awireless channel model, such as a Rayleigh fading model. Communication isperformed using multiple transmit and receive antennas over the channel. Withthese models the signal at any of the receive antennas is the superposition ofthe transmitted signals from each transmit antenna independently faded.Therefore, even if the descriptions at the receiver side are completelyindependent, the received signal at each antenna will include some informationfrom each description. This research involves finding the best multipledescription coding strategy for these channels, the theoretical limits of such ascheme, and the efficiency with which it can be implemented.