| With the rapid development of wireless communication technology, people have a higher demand for the quality of communications services. Traditional wireless LAN technology is mainly deployed in the 2.4GHz and 5GHz ISM bands, these lower frequency spectrum resources have now become saturated, so people focus on the higher millimeter-wave frequency band. The Millimeter wave wireless communication technology is arising at the histocic moment. Due to its shorter wavelength, larger broadband and other characteristics,millimeter wave can provide a higher transmission capability. Therefore, millimeter-wave wireless communication technology has become a hot research topic in recent years. At present, there are multiple 60GHz millimeter wave wireless communication standards, for instance, IEEE802.15.3c, IEEE802.11 ad and so on. IEEE802.11ay is the enhanced version of 11 ad standard, and it is still in the development progress. Multiple antenna technology, channel bonding technology are used in the 11ay system. These technologies will greatly improve the performance of millimeter-wave communication systems. In this paper, we focus on channel state information feedback and hybrid precoding in 60GHz millimeter-wave wireless communication system.After a detailed analysis of the feedback scheme in IEEE802.11 ad and IEEE802.11n system, this paper proposed a broadband time domain CSI feedback scheme for 11 ay system.A complete feedback process is proposed, and the corresponding frame format is designed.The proposed scheme will set up a threshold for the gain/magnitude of the each tap, thus all channel taps can be sub-divided into valid paths and invalid ones. It is proposed to feedback only the delay information and gain information of those valid paths. A three-stage coding method for delay length indication, the valid path indication, and the gain of valid path indication for the channel information was developed and it is shown that the overall system feedback overhead can be greatly reduced. This paper analyzes and compares the feedback overhead of three different feedback schemes. It is concluded that the proposed scheme can greatly reduce the feedback overhead compared with the frequency domain feedback scheme in IEEE802.11n. Due to the limitation of the number of feedback taps in the 11ad feedback scheme, the proposed scheme can provide more channel state information.Multiple antenna array will be utilized in 11 ay. Considering the limitation of cost and power consumption, the traditional MIMO precoding technique is not suitable for the millimeter-wave large-scale antenna system. Instead, the hybrid precoding technology is proposed for the millimeter wave multiple antenna system. In this paper, the hybrid precoding design problem is analyzed. Three kinds of hybrid precoding design algorithms, such as the Orthogonal Matching Pursuit (OMP) based hybrid precoding algorithm, a low complexity hybrid precoding algorithm, as well as the minimal alternating hybrid precoding algorithm,are simulated by MATLAB. The transmission rate is utilized as the metric to assess the achievable performance of three algorithms for comparison. The simulation results show us that, the hybrid precoding algorithm can realize the best performance, and the minimum alternating algorithm will obtain the performance inferior to the hybrid precoding algorithm.While the performance of the orthogonal matching tracking algorithm is the worst. |
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