Research On MIMO Pre-coding And Detection In Broadcast Channel

The Next Generation Broadcasting Network (NGB) based on the overall conversion of digital cable television and China Mobile Multimedia Broadcasting (CMMB) is constructed as a whole broadband interactive broadcast television network. According to the characteristics of different services, NGB manages network sources and spectrum resources adaptively to give users a more comprehensive and individual communication experience, and significantly improves the system spectrum efficiency.In order to improve the spectrum utilization and transmission reliability, The Next Generation Broadcast-Wireless (NGB-W) network applies MIMO (Multiple-InputMultiple-Output) technology to improve system capacity and the robustness of signal transmission as far as possible. In a mobile communication network, the development of MIMO technology has been very mature. Compared with the traditional SISO (Single-Input Single-Output) system, MIMO technology applying spatial multiplexing and diversity can obtain higher capacity and transmission reliability. MIMO system requires the full scattering multipath channel. The richer multipath, the better. Because the height of broadcasting base station antenna is relatively high, the direct component is relatively strong in the signal transmission process and the scattering is not sufficient. The phenomenon leads to the spatial correlation of channel, and the spatial correlation of channel will reduce the capacity of the channel and degrade the performance of system. Unlike two-way communication system in LTE and WIMAX, broadcasting system does not have a return channel and is unable to feed back channel information. According to the scenarios of the next generation network of wireless radio and television, we need to design multi-antenna diversity and enhanced multiplexing scheme to meet the requirements of performance.This paper generates a NGB-W system channel model in reference of the channel model in broadcasting scenarios given by European DVB organization. This model can be used to verify the performance of algorithm of NGB-W in link level. The model is introduced from the multipath effect, cross polarization factor, the Doppler frequency shift and the spatial correlation of channel. This paper takes V-BLAST system as an example and introduces the common multi-antenna signal detection algorithms, including linear detection and nonlinear detection. We compare the performance of the algorithms by the simple simulation. It has been shown that the performance of MIMO systems is significantly degraded when spatial correlation exists. In this paper, we investigate a rotational precoding and phase hopping by means of maximizing the minimum Euclidean distance of joint symbol constellations to improve the performance of systems in broadcasting network.