Research on Space-time Transmission Schemes for Multiple Antenna Multicasting
|School||University of Science and Technology of China|
|Course||Communication and Information System|
|Keywords||Multi- antenna multicast system Maximum and minimum beamforming Orthogonal space- time block codes Delay channel state information Interrupt performance|
The growth in demand for wireless multimedia services, and especially strong demand for mobile operators and users of the mobile TV business to promote the development of the multimedia broadcast / multicast service. On the other hand, the multi-antenna technology to improve spectral efficiency and transmission reliability without increasing the bandwidth and transmit power. Consider the multi-antenna technology is applied to the multicast communication can effectively improve the performance of the multicast system, which is a multi-antenna multicast transmission. Will transmitter beamforming technology applied to a multi-antenna multicast system, its capacity obtained with the increase of the number of transmit antennas increases, approaching the capacity of the multicast system. However, this requires transmitting side knows the ideal channel state information, is difficult to achieve in practical systems. Therefore, the transmission scheme for multi-antenna multicast under non-ideal channel state information system design and performance analysis is worth studying. In multicast transmission, when any user in the system can not be received correctly, the base station needs to all users retransmission the information, resulting in waste of radio resources. In order to reduce the interruption performance of the retransmission, analysis multicast system has important significance. Firstly, only get the delay of the channel state information for the base station when the user moves the scene design of the adaptive transmission scheme. Because the channel state information does not match, the conventional molding method of minimum and maximum beam will result in a very high system interrupts. To solve this problem, this paper first use of delayed channel state information and the Doppler shift of the channel capacity estimates, estimated binding capacity of the new minimum and maximum beamforming method, when the user moves the lower speed, the system close to the ideal channel state information time performance. When the user moves the high speed, the decline in the performance of the method proposed in this paper. Further study the new minimum and maximum beamforming methods and orthogonal space-time block codes approach mode switching problem, and for the user mobile speed very different scene in the multicast group user packet transmission scheme. The simulation results show that, when the user moves the speed is higher, tend to choose the method of orthogonal space-time block codes; Users packet transmission in less number of transmit antennas or lower base station transmit power at outperforms OSTBC code. The article also studies the performance of multi-antenna multicast system interrupt. Assuming that users are uniformly distributed within a cell, the base station using the method of transmission of the open-loop orthogonal space-time block codes derived multi-antenna multicast system outage probability expression. Simulation results verify the correctness of the results of the derivation, and indicates certain outage probability requirements, a multicast system reaches the maximum transmission rate with the increase of the number of transmit antennas increases, as the number of users and the cell radius increases. reduced. When the number of transmit antennas is limited, in order to improve the diversity gain of the system, further analysis of the system performance when using a plurality of time slot transmission mode. Simulation results show that when the number of transmit antennas small cell radius and a larger number of users, the system reaches a maximum transmission rate of the optimal number of time slots greater than one, the transmission rate of the plurality of slots multicast transmission mode obviously superior In the conventional single slot the multicast transmission mode.