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电磁波在自由空间中的全向辐射特性在无线通信领域一直被认为是一个巨大缺点,但在网络环境下该特性可被用来提高无线通信系统的性能.考虑在一个无线网络中,M个节点通过一个交换节点来相互交换各自信息.不同于传统传输方式,交换节点将对自己接收到的这M份独立信息进行联合编码,再利用电磁波全向辐射特性向所有节点同时发送相同码字.对于这种新型网络编码方式,本文给出了它对应的M维空时纠错码的数学定义,并证明了一些关于码本性能的基本定理,为构造性能较好的码本奠定了基础.这种同时引入空域和时域冗余的纠错码本有效地提高了发射天线电磁能的利用率,因此可以出设计高码率且检错纠错性能较好的码本,同时带有数据分布式处理特点的译码算法也可以有效降低复杂度.值得强调的是,新型码本的实例已经推翻了纠错码理论中具有检错纠错功能的码本码率不能为1的传统思维.
The omni-directional radiation characteristics of electromagnetic waves in free space has been considered as a huge disadvantage in the field of wireless communications, but this feature can be used to improve the performance of wireless communication systems in a network environment. Considering that in a wireless network, M nodes Exchange information with each other through a switching node.Different from the traditional transmission mode, the switching node will jointly encode the M pieces of independent information it has received and then send the same codeword to all the nodes by using the electromagnetic wave omni-directional radiation characteristic. In this new network coding method, the mathematical definition of its corresponding M-dimensional space-time error correction code is given and some basic theorems about the performance of the codebook are proved, which paves the way for constructing better performance codebook. The error correction codebook, which introduces both airspace and time domain redundancy, effectively improves the electromagnetic energy utilization efficiency of the transmitting antenna. Therefore, a codebook with high code rate and good error detection and correction performance can be designed with data distribution It is worth emphasizing that the examples of the new codebook have overturned the concept of error detection and correction in error correction code theory Codebook rate can not be traditional thinking 1.