Digital signal transmitting device and receiving device as well as digital signal modulation method and demodulation method

Abstract

The invention discloses a digital signal transmitting device and a digital signal receiving device as well as a digital signal modulation method and a digital signal demodulation method. The digital signal transmitting device and the digital signal receiving device of the invention are characterized in that the digital signal transmitting device and the digital signal receiving device comprise a plurality of constellation point mapping modules and a plurality of constellation point de-mapping modules respectively; and different QAM mapping is adopted between each mapping module and each de-mapping module. The digital signal modulation method and the digital signal demodulation method of the invention are characterized in that one code stream is divided into a plurality of sub code streams which are subjected to mapping, and correspondingly, one baseband symbol stream is divided into a plurality of symbol streams which are subjected to de-mapping. With the digital signal transmitting device and receiving device as well as the digital signal modulation method and demodulation method of the invention adopted, according to problems such as too many error-correcting code modes and performance loss of modulation modes such as 32QAM and 128QAM, the flexibility of code rate and receiving threshold can be realized through the modulation modes of hybrid constellation points, and therefore, the complexity of a system can be decreased, and performance can be improved.

Description

technical field [0001] The present invention relates to a modulation and demodulation device and a corresponding method of a communication system, more specifically, to a digital signal transmitting device, a receiving device and a corresponding modulation and demodulation method. Background technique [0002] Existing communication systems, such as DVB-T2 and DTMB, have many different modulation modes and error correction code modes in order to meet different code rate and receiving threshold requirements. For example, DTMB has different modulation modes such as QPSK, 16QAM, 32QAM and 64QAM, and three different LDPC modes of 0.4, 0.6 and 0.8. But DTMB has only one modulation method in any mode. Different channels of DVB-T2 can use different modulation methods, but only one modulation method will be used for the same service flow. [0003] Such a system has the following problems: [0004] 1. For the transmitting end and the receiving end, the diversity of error correcti...

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Problems solved by technology

[0004] 1. For the transmitter and receiver, the diversity of error correction codes increases the complexity of the system more or less

[0005] 2. For the equalization part of a single-carrier system, if decision feedback or similar techniques are used, the higher-order constellation point mapping is more unfavorable to the equalization algorithm. For example, the decision feedback gain of 256QAM is smaller than that of 64QAM, but when higher When the code rate is high, you have to use high-order constellation point mapping

[0006] 3. The QAM mapping of the odd power of 2, such as 32QAM and 128QAM, cannot fully satisfy the conditions of Gray mapping, so there will be performance loss

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